HomeMy WebLinkAboutExhibit 1City of Miami
Phase I
Storm ater Management
Master Plan
Prepared by:
9m4ote:Icoc=4ma Aaceiel
8550 NW 33rc Street, Suite 101
Miami, Florida 33122
January 2011
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In association with:
EAC Consulting, Inc.
815 NW 57th Avenue, Suite 402
Miami, Florida 33126
January 2011 City of Miami Phase I - Stormwater Management Master Plan
City of Miami
Phase I - Stormwater Management Master Plan
Table of Contents
1.0 EXECUTIVE SUMMARY 1-1
1.1 General 1-1
1.2 Data Collection 1-2
1.3 Hydrologic & Hydraulic Modeling of Existing & Condition Land Uses Without City Flood Protection 1-3
1.4 Identification & Ranking of Problem Areas 1-4
1.5 Hydrologic & Hydraulic Modeling of Existing & Future Condition Land Uses with City Flood Protection Projects
Completed, Under Construction, & Under Design 1-5
1.6 Identification of Future City Flood Protection Projects 1-5
1.7 Ranking & Prioritization of Future City Flood Protection Projects & Capital Plan 1-6
2.0 INTRODUCTION 2-1
2.1 General Background 2-1
3.0 DATA COLLECTION & EVALUATION 3-1
3.1 City of Miami 3-2
3.2 Miami -Dade County 3-3
3.3 South Florida Water Management District (SFWMD) 3-4
3.4 National Oceanic & Atmospheric Administration (NOAA) 3-8
3.5 United States Army Corps of Engineers (ALOE) 3-10
3.6 United States Geological Service (USGS) 3-10
3.7 Natural Resources Conservation Service (NRCS) 3-11
3.8 Federal Emergency Management Agency (FEMA) 3-12
3.9 Data Evaluation 3-13
3.9.1 Miami -Dade County DERM Data 3-13
3.9.2 City of Miami Data 3-16
3.10 Data Collection Conclusion Recommendations 3-17
4.0 HYDROLOGIC & HYDRAULIC MODELING OF EXISTING CONDITION LAND USES WITHOUT CITY FLOOD
PROTECTION 4-1
4.1 Miami -Dade DERM XP-XWMM Models 4-1
4.2 General Hydrologic/Hydraulic Model Setup Approach & Methodologies 4-1
4.2.1 Hydrology Model Setup (Runoff Block) 4-2
4.2.2 Hydraulics Model Setup (Exton Block) 4-5
4.2.3 Model Calibration & Verification 4-6
4.2.4 Model Production/Design Storm Event Runs 4-6
4.3 DERM to City of Miami Basin Comparison 4-7
4.4 C-3 Basin Model 4-12
4.4.1 C-3 Basin Summary of CalibrationNerification 4-12
4.4.2 C-3 Basin Production Run Model Assumptions 4-13
4.5 C-4 Basin Model 4-13
4.5.1 C-4 Basin Summary of CalibrationNerification 4-15
4.5.2 C-4 Basin Production Run Model Assumptions 4-17
4.6 C-5 Basin Model 4-19
4.6.1 C-5 Basin Summary of Calibration/Verification 4-20
4.6.2 C-5 Basin Production Run Model Assumptions 4-21
4.7 C-6 Basin Model 4-21
4.7.1 C-6 Basin Summary of CalibrationNerification 4-24
4.7.2 C-6 Basin Production Run Model Assumptions 4-24
4.8 C-7 Basin Model 4-25
4.8.1 C-7 Basin Summary of CalibrationNerification 4-27
4.8.2 C-7 Basin Production Run Model Assumptions 4-28
4.9 DERM XP-SWMM Model Version Update 4-29
4.9.1 C-3 Basin Model Conversion 4-30
4.9.1.1 C-3 Conversion Issues and Resolutions 4-30
4.9.1.2 C-3 Model Results Comparisons 4-31
4.9.2 C-4 Basin Model Conversion 4-32
4.9.2.1 C-4 Conversion Issues and Resolutions 4-32
4.9.2.2 C-4 Model Results Comparisons 4-32
4.9.3 C-5 Basin Model Conversion 4-34
4.9.3.1 C-5 Conversion Issues and Resolutions 4-34
4.9.3.2 C-5 Model Results Comparisons 4-35
4.9.4 C-6 Basin Model Conversion 4-35
4.9.4.1 C-6 Conversion Issues and Resolutions 4-36
4.9.4.2 C-6 Model Results Comparisons 4-36
January 2011 City of Miami Phase I - Stormwater Management Master Plan
4.9.5 C-7 Basin Model Conversion 4-37
4.9.5.1 C-7 Conversion Issues and Resolutions 4-38
4.9.5.2 C-7 Model Results Comparisons 4-38
4.10 Modeling of Existing Conditions Conclusion & Recommendations 4-39
5.0 IDENTIFICATION & RANKING OF PROBLEM AREAS 5-1
5.1 DERM Flood Problem Area Ranking & Flood Protection Level of Service Procedure 5-1
5.2 City of Miami Revised Flood Problem Area Ranking & Flood Protection Level of Service Procedure 5-2
5.3 Quantifying Methodology for Sub -basin Flooding Severity Indicators 5-5
5.4 Flood Problem Area Ranking Results & Flood Protection Level of Service Results 5-9
5.4.1 Existing versus Future Conditions Comparison 5-11
5.5 Identification & Ranking Procedures Conclusions & Recommendations 5-12
6.0 HYDROLOGIC & HYDRAULIC MODELING OF EXISTING & FUTURE CONDITION LAND USES WITH CITY FLOOD
PROTECTION PROJECTS COMPLETED, UNDER CONSTRUCTION, & UNDER DESIGN 6-1
6.1 Projects Completed & Under Construction 6-1
6.2 Projects Under Design 6-2
6.3 Hydrologic & Hydraulic Model Setup - Representation of Stormwater Projects in XP-SWMM 6-3
6.3.1 New or lncreased Pipe Size 6-3
6.3.2 Exfiltration Trenches 6-4
6.3.3 Gravity Injection Wells 6-5
6.3.4 Stormwater Pump Stations 6-6
6.4 Basin Hydrologic & Hydraulic Model Setup 6-7
6.4.1 C-3 Basin 6-7
6.4.2 C-4 Basin 6-8
6.4.3 C-5 Basin 6-9
6.4.4 C-6 Basin 6-9
6.4.5 C-7 Basin 6-10
6.5 Summary of Results & Rankings - Projects Completed & Under Construction 6-10
6.6 Summary of Results and Rankings - Projects Under Design 6-13
6.7 Sub -basin Rankings & Comparisons - Construction & Under Design Scenarios 6-15
6.8 Analysis of Repetitive Loss Properties 6-17
6.9 FEMA FIRM Flood Zone Comparisons 6-20
6.10 Conclusion of Modeling with City Flood Protection Projects 6-22
7.0 IDENTIFICATION OF FUTURE CITY FLOOD PROTECTION PROJECTS 7-1
7.1 Stormwater Control Measure Criteria Descriptions 7-1
7.1.1 Water Quality Regulatory & Permitting Requirements 7-1
7.1.1.1 Miami -Dade County DERM 7-1
7.1.1.2 South Florida Water Management District 7-2
7.1.1.3 Florida Department of Environmental Protection 7-3
7.1.2 Water Quantity Regulatory and Permitting Requirements 7-3
7.1.2.1 City of Miami 7-3
7.1.2.2 Miami -Dade County DERM 7-4
7.1.2.3 South Florida Water Management District 7-4
7.1.2.4 Florida Department of Transportation 7-5
7.1.2.5 Florida Department of Environmental Protection 7-5
7.1.2.6 Maximum Allowable Water Elevations 7-6
7.2 Stormwater Management Systems 7-6
7.2.1 Positive Drainage with Outfalls 7-6
7.2.2 Exfiltration Trenches 7-7
7.2.3 Dry Retention Basins 7-8
7.2.4 Injection Drainage Wells 7-9
7.2.5 Pump Stations 7-11
7.3 Capital Improvement Project Formulation 7-12
7.3.1 Volumetric Analysis 7-12
7.3.2 Rank #1 - Sub -Basin CC6-N-12 7-13
7.3.3 Rank #2 - Sub -Basin CC7-S-25 7-15
7.3.4 Rank #3 - Sub -basin CC7-S-21 7-17
7.3.5 Rank #4 - Sub -Basin C6-N-17 7-20
7.3.6 Rank #5 - Sub -basin CC7-S-24 7-22
7.3.7 Rank #6 - Sub -Basin C4-S-17 7-24
7.3.8 Rank #7 - Sub -Basin CC6-N-11 7-26
7.3.9 Rank #8 - Sub -Basin C6-S-12 7-28
7.3.10 Rank #9 - Sub -Basin CC4-S-21 7-30
7.3.11 Rank #10 - Sub -Basin CC7-S-26 7-31
7.3.12 Rank #11 - Sub -Basin C4-S-18 7-33
7.3.13 Rank #12 - Sub -Basin C4-S-23 7-35
7.3.14 Rank #13 - Sub -Basin C5-S5-3 7-37
7.3.15 Rank #14 - Sub -Basin CC6-S-8 7-39
7.3.16 Rank #15 - Sub -Basin DA1-SE-2 7-41
7.4 Planning -Level Cost Estimates 7-43
7.4.1 Cost Estimate Procedures & Unit Costs 7-43
7.4.2 Cost Estimate Results 7-44
January 2011 City of Miami Phase I - Stormwater Management Master Plan
8.0 RANKING & PRIORITIZATION OF FUTURE PROJECTS & CAPITAL PLAN 8-1
8.1 Ranking Procedure 8-1
8.1.1 Ranking Results 8-1
8.2 5-Year Capital Improvement Plan 8-2
8.3 Conclusions & Recommendations 8-2
III
January 2011 City of Miami Phase I - Stormwater Management Master Plan
LIST OF FIGURES
FIGURE 2-1 - BASINS AND WATERSHEDS WITHIN THE CITY OF MIAMI 2-1
FIGURE 3-1 - MIAMI-DADE COUNTY GIS DATA PORTAL 3-3
FIGURE 3-2 - MAIN DBHYDRO PORTAL 3-5
FIGURE 3-3 - DBHYDRO BROWSER MENU 3-5
FIGURE 3-4 - SFWMD GIS DATA DISTRIBUTION SITE 3-6
FIGURE 3-5 - SFWMD MONITORING STATIONS 3-7
FIGURE 3-6 - SFWMD ERP PERMIT LOCATIONS WITHIN THE CITY OF MIAMI 3-8
FIGURE 3-7 - NOAA CO-OPS ODIN DATA ACCESS SITE 3-9
FIGURE 3-8 - NOAA GIS DATA SITE 3-9
FIGURE 3-9 - USGS GROUNDWATER WELL DATA SITE 3-11
FIGURE 3-10 - USDA'S GEOSPTIAL DATA GATEWAY SITE 3-12
FIGURE 4-1 - BASINS AND WATERSHEDS WITHIN THE CITY OF MIAMI 4-8
FIGURE 5-1 - RASTER BASED DEM 5-6
FIGURE 5-2 - ROADWAYS LINES TO POINTS 5-6
FIGURE 5-3 - PROPERTY POLYGONS TO POINTS 5-7
FIGURE 5-4 - DEM TO POINTS 5-8
FIGURE 5-5 - SAMPLE OF FLOOD PLAIN MAPPING RESULTS 5-10
FIGURE 6-1- AREA ATTRIBUTED TO AN EXFILTRATION TRENCH LENGTH 6-4
FIGURE 6-2 - REPETITIVE LOSS PROPERTIES WITHIN THE DA1-SE-2 BASIN 6-20
FIGURE 6-3 -FEMA FLOOD ZONE AH AND AE COMPARISON 1 6-21
FIGURE 6-4 - FEMA FLOOD ZONE AH AND AE COMPARISON 2 6-21
FIGURE 6-5 - FEMA FLOOD ZONE AH AND AE COMPARISON 3 6-22
FIGURE 7-1 - TYPICAL EXFILTRATION TRENCH SECTIONS 7-8
FIGURE 7-2 - TYPICAL INJECTION DRAINAGE WELL 7-10
FIGURE 7-3 - TYPICAL STORMWATER PUMP STATION PLAN 7-11
FIGURE 7-4 - SUB -BASIN CC6-N-12 TOPOGRAPHIC TRENDS 7-13
FIGURE 7-5 - SUB -BASIN CC7-S-25 TOPOGRAPHIC TRENDS 7-15
FIGURE 7-6 - SUB -BASIN CC7-S-21 TOPOGRAPHIC TRENDS 7-18
FIGURE 7-7 - SUB -BASIN C6-N-17 TOPOGRAPHIC TRENDS 7-20
FIGURE 7-8 - SUB -BASIN CC7-S-24 TOPOGRAPHIC TRENDS 7-22
FIGURE 7-9 - SUB -BASIN C4-S-17 TOPOGRAPHIC TRENDS 7-24
FIGURE 7-10 - SUB -BASIN CC6-N-11 TOPOGRAPHIC TRENDS 7-26
FIGURE 7-11 - SUB -BASIN C6-S-12 TOPOGRAPHIC TRENDS 7-28
FIGURE 7-12 - SUB -BASIN CC4-S-21 TOPOGRAPHIC TRENDS 7-30
FIGURE 7-13 - SUB -BASIN CC7-S-26 TOPOGRAPHIC TRENDS 7-32
FIGURE 7-14 - SUB -BASIN C4-S-18 TOPOGRAPHIC TRENDS 7-34
FIGURE 7-15 - SUB -BASIN C4-S-23 TOPOGRAPHIC TRENDS 7-36
FIGURE 7-16 - SUB -BASIN C5-S5-3 TOPOGRAPHIC TRENDS 7-38
FIGURE 7-17 - SUB -BASIN CC6-S-8 TOPOGRAPHIC TRENDS 7-40
FIGURE 7-18 - SUB -BASIN DA1-SE-2 TOPOGRAPHIC TRENDS 7-42
IV
January 2011 City of Miami Phase I - Stormwater Management Master Plan
LIST OF TABLES
TABLE 2-1 - BASIN AND WATERSHED AREAS WITHIN THE CITY OF MIAMI 2-2
TABLE 4-1 - CITY OF MIAMI TO DERM SUB -BASIN UNION RESULTS 4-8
TABLE 4-2 - CITY OF MIAMI TO DERM SUB -BASIN UNION RESULTS 4-9
TABLE 4-3 - ORIGINAL MODEL DATA PROVIDED BY DERM PER BASIN 4-29
TABLE 4-4 - C-3 BASIN RESULTS COMPARISON OF ORIGINAL AND CONVERTED XP-SWMM MODELS - EXISTING LAND
USE 4-31
TABLE 4-5 - C-3 RESULTS COMPARISON OF SUB -BASINS WITHIN THE CITY OF MIAMI - EXISTING LAND USE 4-31
TABLE 4-6 - C-3 CONTINUITY ERROR COMPARISON OF ORIGINAL AND CONVERTED XP-SWMM MODELS - EXISTING
LAND USE 4-32
TABLE 4-7 - C-4 RESULTS COMPARISON OF ORIGINAL AND CONVERTED XP-SWMM MODELS - EXISTING LAND USE4-33
TABLE 4-8 - C-4 RESULTS COMPARISON OF SUB -BASINS WITHIN THE CITY OF MIAMI - EXISTING LAND USE 4-33
TABLE 4-9 - C-4 CONTINUITY ERROR COMPARISON OF ORIGINAL AND CONVERTED XP-SWMM MODELS - EXISTING
LAND USE 4-33
TABLE 4-10- C-4 RESULTS COMPARISON OF ORIGINAL AND CONVERTED XP-SWMM MODELS - FUTURE LAND USE 4-33
TABLE 4-11 - C-4 RESULTS COMPARISON OF SUB -BASINS WITHIN THE CITY OF MIAMI - FUTURE LAND USE 4-34
TABLE 4-12 - C-4 CONTINUITY ERROR COMPARISON OF ORIGINAL AND CONVERTED XP-SWMM MODELS - FUTURE
LAND USE 4-34
TABLE 4-13 - C-5 RESULTS COMPARISON OF ORIGINAL AND CONVERTED XP-SWMM MODELS - EXISTING LAND USE4-35
TABLE 4-14- C-5 RESULTS COMPARISON OF SUB -BASINS WITHIN THE CITY OF MIAMI - EXISTING LAND USE 4-35
TABLE 4-15 - C-5 CONTINUITY ERROR COMPARISON OF ORIGINAL AND CONVERTED XP-SWMM MODELS - EXISTING
LAND USE 4-35
TABLE 4-16 - C-6 RESULTS COMPARISON OF ORIGINAL AND CONVERTED XP-SWMM MODELS - EXISTING LAND USE4-36
TABLE 4-17- C-6 RESULTS COMPARISON OF SUB -BASINS WITHIN THE CITY OF MIAMI - EXISTING LAND USE 4-36
TABLE 4-18- C-6 CONTINUITY ERROR COMPARISON OF ORIGINAL AND CONVERTED XP-SWMM MODELS - EXISTING
LAND USE 4-37
TABLE 4-19- C-6 RESULTS COMPARISON OF ORIGINAL AND CONVERTED XP-SWMM MODELS - FUTURE LAND USE4-37
TABLE 4-20- C-6 RESULTS COMPARISON OF SUB -BASINS WITHIN THE CITY OF MIAMI - FUTURE LAND USE 4-37
TABLE 4-21 - C-6 CONTINUITY ERROR COMPARISON OF ORIGINAL AND CONVERTED XP-SWMM MODELS - FUTURE
LAND USE 4-37
TABLE 4-22 - C-7 BASIN RESULTS COMPARISON OF ORIGINAL AND CONVERTED XP-SWMM MODELS - EXISTING LAND
USE 4-38
TABLE 4-23- C-7 RESULTS COMPARISON OF SUB -BASINS WITHIN THE CITY OF MIAMI - EXISTING LAND USE 4-38
TABLE 4-24 - C-7 CONTINUITY ERROR COMPARISON OF ORIGINAL AND CONVERTED XP-SWMM MODELS - EXISTING
LAND USE 4-39
TABLE 4-25 - XP-SWMM BASIN MODELS TO BE USED 4-40
TABLE 5-1 - XP-SWMM BASIN MODELS USED BY SCENARIOS 5-9
TABLE 5-2 - TOP 15 BASINS FOR THE EXISTING CONDITION MODELS BASED ON THE FPSS 5-10
TABLE 5-3 - TOP 15 BASINS FOR THE FUTURE CONDITION MODELS BASED ON THE FPSS 5-11
TABLE 5-4 - STAGE COMPARISON BETWEEN EXISTING AND FUTURE CONDITIONS MODELS FOR THE C-6 BASIN5-12
TABLE 5-5-XP-SWMM BASIN MODELS USED BY SCENARIOS 5-12
TABLE 6-1 - PROJECT STATUS TOTALS 6-1
TABLE 6-2 - XP-SWMM BASIN MODELS USED IN THE BASELINE SCENARIO 6-1
TABLE 6-3 - XP-SWMM BASIN MODELS - CONSTRUCTION SCENARIO 6-2
TABLE 6-4 - XP-SWMM BASIN MODELS - UNDER DESIGN SCENARIO 6-3
CALCULATION EXAMPLE 6-5 - EXFILTRATION TRENCH EXTRACTION METHODOLOGY EXAMPLE 6-5
TABLE 6-6 - TOTAL LENGTH OF EXFILTRATION TRENCH INCORPORATED INTO EACH MODEL 6-5
CALCULATION EXAMPLE 6-7 - GRAVITY INJECTION WELL EXTRACTION METHODOLOGY EXAMPLE 6-6
TABLE 6-8 - PUMP STATIONS WITHIN THE CITY OF MIAMI 6-7
TABLE 6-9 - MAIN PROJECT COMPONENTS INCORPORATED INTO THE C-3 MODELS SUB -BASINS 6-8
TABLE 6-10 - MAIN PROJECT COMPONENTS INCORPORATED INTO THE C-4 MODEL'S SUB -BASINS 6-8
TABLE 6-11 - MAIN PROJECT COMPONENTS INCORPORATED INTO THE C-5 MODEL'S SUB -BASINS 6-9
TABLE 6-12 - MAIN PROJECT COMPONENTS INCORPORATED INTO THE C-6 MODEL'S SUB -BASINS 6-9
TABLE 6-13 - MAIN PROJECT COMPONENTS INCORPORATED INTO THE C-7 MODEL'S SUB -BASIN 6-10
TABLE 6-14 - STAGE COMPARISON - BASELINE TO CONSTRUCTION SCENARIOS (NGVD) 6-11
TABLE 6-15 - MODEL RESULTS COMPARISON - CONSTRUCTION TO UNDER DESIGN SCENARIOS (NGVD) 6-13
TABLE 6-16 - SUB -BASINS RANKINGS AND COMPARISONS 6-15
TABLE 6-17-SUB-BASINS WITH MAXIMUM NUMBER OF REPETITIVE LOSS PROPERTIES 6-17
TABLE 6-18- SUB -BASINS WITH MAXIMUM NUMBER OF REPETITIVE LOSS PROPERTIES 6-19
TABLE 7-1 - SFWMD ALLOWABLE DISCHARGE RATE FORMULAS FOR BASINS WITH RESTRICTED DISCHARGE 7-5
CALCULATION EXAMPLE 7-2 - EXFILTRATION TRENCH EXTRACTION VOLUME CALCULATION EXAMPLE 7-8
CALCULATION EXAMPLE 7-3- RETENTION BASIN VOLUME CALCULATION EXAMPLE 7-9
CALCULATION EXAMPLE 7-4 - INJECTION WELL VOLUME CALCULATION EXAMPLE 7-11
TABLE 7-5 - SUB -BASIN CC6-N-12 STAGE REDUCTION ESTIMATES 7-14
TABLE 7-6 - SUB -BASIN CC6-N-12 PROPOSED STORMWATER MANAGEMENT SYSTEM COMPONENTS 7-15
TABLE 7-7 - SUB -BASIN CC7-S-25 STAGE REDUCTION ESTIMATES 7-16
January 2011 City of Miami Phase I - Stormwater Management Master Plan
TABLE 7-8- SUB -BASIN CC7-S-25 PROPOSED STORMWATER MANAGEMENT SYSTEM COMPONENTS 7-17
TABLE 7-9- SUB -BASIN CC7-S-21 STAGE REDUCTION ESTIMATES 7-19
TABLE 7-10 - SUB -BASIN CC7-S-21 PROPOSED STORMWATER MANAGEMENT SYSTEM COMPONENTS 7-20
TABLE 7-11 - SUB -BASIN C6-N-17 STAGE REDUCTION ESTIMATES 7-21
TABLE 7-12 - SUB -BASIN C6-N-17 PROPOSED STORMWATER MANAGEMENT SYSTEM COMPONENTS 7-22
TABLE 7-13 - SUB -BASIN CC7-S-24 STAGE REDUCTION ESTIMATES 7-23
TABLE 7-14 - SUB -BASIN CC7-S-24 PROPOSED STORMWATER MANAGEMENT SYSTEM COMPONENTS 7-23
TABLE 7-15- SUB -BASIN C4-S-17 STAGE REDUCTION ESTIMATES 7-25
TABLE 7-16- SUB -BASIN C4-S-17 PROPOSED STORMWATER MANAGEMENT SYSTEM COMPONENTS 7-25
TABLE 7-17- SUB -BASIN CC6-N-11 STAGE REDUCTION ESTIMATES 7-27
TABLE 7-18 - SUB -BASIN CC6-N-11 PROPOSED STORMWATER MANAGEMENT SYSTEM COMPONENTS 7-27
TABLE 7-19 - SUB -BASIN C6-S-12 STAGE REDUCTION ESTIMATES 7-29
TABLE 7-20-'SUB-BASIN C6-S-12 PROPOSED STORMWATER MANAGEMENT SYSTEM COMPONENTS 7-29
TABLE 7-21 - SUB -BASIN CC4-S-21 STAGE REDUCTION ESTIMATES 7-31
TABLE 7-22- SUB -BASIN CC4-S-21 PROPOSED STORMWATER MANAGEMENT SYSTEM COMPONENTS 7-31
TABLE 7-23 - SUB -BASIN CC7-S-26 STAGE REDUCTION ESTIMATES 7-33
TABLE 7-24- SUB -BASIN CC7-S-26 PROPOSED STORMWATER MANAGEMENT SYSTEM COMPONENTS 7-33
TABLE 7-25- SUB -BASIN C4-S-18 STAGE REDUCTION ESTIMATES 7-35
TABLE 7-26- SUB -BASIN C4-S-18 PROPOSED STORMWATER MANAGEMENT SYSTEM COMPONENTS 7-35
TABLE 7-27 - SUB -BASIN C4-S-23 STAGE REDUCTION ESTIMATES 7-37
TABLE 7-28- SUB -BASIN C4-S-23'PROPOSED STORMWATER MANAGEMENT SYSTEM COMPONENTS 7-37
TABLE 7-29 - SUB -BASIN C5-S5-3 STAGE REDUCTION ESTIMATES 7-39
TABLE 7-30 - SUB -BASIN C5-S5-3 PROPOSED STORMWATER MANAGEMENT SYSTEM COMPONENTS 7-39
TABLE 7-31 - SUB -BASIN CC6-S-8 STAGE REDUCTION ESTIMATES 7-41
TABLE 7-32 - SUB -BASIN CC6-S-8 PROPOSED STORMWATER MANAGEMENT SYSTEM COMPONENTS 7-41
TABLE 7-33 - SUB -BASIN DA1-SE-2 STAGE REDUCTION ESTIMATES 7-43
TABLE 7-34 - SUB -BASIN DA1-SE-2 PROPOSED STORMWATER MANAGEMENT SYSTEM COMPONENTS 7-43
TABLE 7-35 - PROBABLE CONSTRUCTION COSTS PER SUB -BASIN 7-45
TABLE 8-1 - PROBABLE CONSTRUCTION COSTS PER SUB -BASIN 8-2
VI
January 2011
City of Miami Phase I - Stormwater Management Master Plan
ATTACHMENT A
ATTACHMENT B
ATTACHMENT C
ATTACHMENT D
ATTACHMENT E
ATTACHMENT F
ATTACHMENT G
ATTACHMENT H
ATTACHMENT
ATTACHMENT J
ATTACHMENT K
ATTACHMENT L
ATTACHMENT M
ATTACHMENT N
ATTACHMENT 0
ATTACHMENT P
ATTACHMENT Q
ATTACHMENT R
ATTACHMENT S
ATTACHMENT T
ATTACHMENT U
ATTACHMENT V
ATTACHMENT W
ATTACHMENT X
ATTACHMENT
ATTACHMENT Z -
ATTACHMENT AA -
ATTACHMENT BB -
LIST OF ATTACHMENTS
CITY OF MIAMI DATA CATALOG
MIAMI-DADE COUNTY DATA CATALOG
MAP OF CITY OF MIAMI AND DERM SUBBASINS
C-3 BASIN CONVERSION ISSUES AND RESOLUTIONS, ORIGINAL AND CONVERTED MODEL
RESULTS AND COMPARISONS
C-4 BASIN CONVERSION ISSUES AND RESOLUTIONS, ORIGINAL AND CONVERTED MODEL
RESULTS, AND COMPARISONS
C-5 BASIN CONVERSION ISSUES AND RESOLUTIONS, ORIGINAL AND CONVERTED MODEL
RESULTS, AND COMPARISONS
C-6 BASIN CONVERSION ISSUES AND RESOLUTIONS, ORIGINAL AND CONVERTED MODEL
RESULTS, AND COMPARISONS
C-7 BASIN CONVERSION ISSUES AND RESOLUTIONS, ORIGINAL AND CONVERTED MODEL
RESULTS, AND COMPARISONS
CITY OF MIAMI SUB -BASIN DELINEATION AND ORIGINAL DERM STORMWATER MASTER PLAN
BASIN DELINEATION MAPS
SUB -BASIN DELINEATION
'FLOOD PLAIN MAPS
SUB -BASIN RANKING TABLES
MAP OF MODEL SUB -BASINS SHOWING FPSS RANKINGS
CITY OF MIAMI PROJECT LISTING
SUB -BASIN RAINFALL EXTRACTIONS
PUMP STATION MODEL INPUT PARAMETERS AND LOCATION SKETCHES
FIGURES - SUB -BASIN IMPROVEMENTS
MODEL RESULTS - CONSTRUCTION SCENARIO
SUB -BASIN RANKINGS - CONSTRUCTION SCENARIO
FLOOD PLAIN MAPS - CONSTRUCTION SCENARIO
MODEL RESULTS - UNDER DESIGN SCENARIO
SUB -BASIN RANKINGS - UNDER DESIGN SCENARIO
FLOOD PLAIN MAPS - UNDER DESIGN SCENARIO
MAPS SHOWING REPETITIVE LOSS PROPERTIES WITHIN FEMA FLOOD ZONES AH & AE
MAPS SHOWING FLOOD PLAIN COMPARISONS TO FEMA FLOOD ZONES AH & AE
SUB -BASIN STORMWATER MANAGEMENT IMPROVEMENT PROJECT SKETCHES
PROBABLE CONSTRUCTION COST ESTIMATES
RANKED PROBABLE CONSTRUCTION COST ESTIMATES
January 2011
City of Miami Phase I - Stormwater Management Master Plan
1.(0 1,EXECUTWE SLIM:
1.1 General
The City of Miami (City) encompasses approximately 56 square miles (SM) of east -
central Miami -Dade County (County). Of this area, approximately 36 SM are located in
upland areas, while 20 SM are within the coastal waters of Biscayne Bay. The
mainland portion of the City (approximately 34 SM, excluding barrier islands) is located
within the C-3, C-4, C-5, C-6, C-7, DA-1/South Biscayne Bay and North Biscayne Bay
Basins or Watersheds. The figure below shows the City limits and the extent of the
major basins within the City.
Legend
Q City of Miami limits
Major Basins in City of Miami
C-3
C-4
Li G5
I iC-6
C-7
r Biscayne North
Biscayne South
1Island
Basin Boundaries (DERM)
The City last prepared a Stormwater Drainage Master Plan in 1986 for the mainland
areas of the City, which excluded the barrier islands located within the City's limits. In
order for the City to improve its National Flood Insurance Program (NFIP) Community
Rating System (CRS) classification from the current Class 8 rating to a Class 4 rating,
the current stormwater master plan would have had to have been updated within the
previous five years. Furthermore, to achieve a Class 4 rating, at least 50% of the
mainland portion of the City must be addressed in the update and the 100-year, 3-day
January 2011 City of Miami Phase I - Stormwater Management Master Plan
design storm event must be evaluated. By improving the CRS rating from a Class 8 to
Class 4, the City's residents would realize an additional 20% savings on their flood
insurance coverage premiums, which will be a substantial savings to the community and
confirms the need to update the current stormwater master plan.
In order to improve Miami -Dade County's CRS classification, the Miami -Dade County
Department of Environmental Resources Management (DERM) developed Stormwater
Management Master Plans for the main basins and watersheds within the County. To
standardize these master plans, DERM established detailed procedures for developing
and applying hydrologic/hydraulic computer models, establishing basin flood protection
levels of service, ranking and prioritizing problem areas, and ranking and prioritizing
flood protection projects. These procedures were documented in Part I and Part ll,
Planning Criteria Procedures dated March 1995 and were approved by the Federal
Emergency Management Agency (FEMA) and Federal Insurance .and Mitigation
Administration (FIMA) which oversee the NFIP. DERM used these procedures to
develop the .Stormwater Management Master Plans for the C-3, C-4, C-5, C-6 .and C-7
basins, which cover approximately 20.7 SM or 60% of the City's mainland area.
Based on the readily available information developed by DERM for 60% of the mainland
areas of the City, the City's Public Works Department determined that the most cost-
effective approach to update the City's Stormwater Management Master Plan is to
update it in two phases.
A.D.A. Engineering, Inc. (ADA) was contracted by the City under the Professional
Services Agreement for Miscellaneous Civil Engineering Professional Services dated
February 7, 2008 (Contract No. 06-07-019) to complete Phase I of the SWMMP. Phase
I of the SWMMP The results and findings of each of the primary tasks prepared as part
of the Phase I SWMMP are detailed in the following subsections.
1.2 Data Collection
The data collection task required collecting data from the various entities with
jurisdiction or that maintain data within the City's limits. Data was requested and/or
collected from the flowing entities:
• City of Miami
• Miami -Dade County
• South Florida Water Management District (SFWMD)
• National Oceanic and Atmospheric Administration (NOAA)
• Army Corps of Engineers (ACOE)
• United States Geological Service (USGS)
• Natural Resources Conservation Service (MRCS)
• Federal Emergency Management Agency (FEMA) - National Flood Insurance
Program
Sufficient data was collected to proceed with the development of this stormwater master
plan update.
1-2
January 2011 City of Miami Phase I - Stormwater Management Master Plan
Additionally, based on the data that was known to be available as well as based on an
evaluation of the data already collected as part of this task, there was adequate and
sufficient information available to complete Phase I of the City of Miami SWMMP
update. As part of the data collection effort for Phase I of the SWMMP, preliminary data
was also collected for Phase II to streamline future data collection efforts. Evaluation of
data collected also indicated that there is adequate data to complete Phase II of the City
of Miami SWMMP update. Additional data collection activities will also be performed
and documented for Phase II.
1.3 Hydrologic & Hydraulic Modeling of Existing & Condition Land Uses
Without City Flood Protection
To support the development of the stormwater management master plans for the C-3,
C-4, C-5, C-6 and. C-7 .basins, DERM implemented previously established procedures
for developing, calibrating and verifying hydrologic, hydraulic and water quality models
using the XP-SWMM computer model. These procedures are documented .in .Part I,
Volumes 2 and 3, of the "Stormwater Planning Procedures" document, dated March
1995 which was obtained from DERM and were used by DERM to develop existing
conditions XP-SWMM models for each basin, using the 2005 Miami -Dade County land
use data. These models were calibrated and verified using available measured rainfall,
stage, and flow data recorded for extreme storm events. Once the models were
calibrated and verified, the models were adjusted to perform design event simulations
(production runs) for the following design storm events:
O 5-year, 1-day
O 10-year, 1-day
O 25-year, 3-day
O 50-year, 3-day
O 100-year,3-day
For some basins, the existing conditions models were further revised to incorporate
2025 land use data. Once revised, the future land use condition models were also
simulated for these five design storm events. DERM compared the modeling results
between existing and future land uses and found little to no difference between the
existing and future land use models. Therefore, DERM decided not to evaluate future
land uses in further refinements of these master plans.
The DERM Stormwater Master Plans for the C-3, C-4, C-5, C-6 and C-7 offered well
documented model development information as well as complete and functioning
electronic versions of their respective XP-SWMM models. Each DERM basin
stormwater master plan provided sufficient detail regarding the development,
calibration, and verification of the individual models available and the assumptions
made for each basin.
The purpose of this task was to establish existing baseline condition peak stages, flows
and flood durations for City basins located within the limits of the C-3, C-4, C-5, C-6,
and C-7 basins previously assessed by DERM. This task primarily used the data
collected from DERM to establish the peak stages, flows and flood durations for the 5-
1-3
January 2011 City of Miami Phase I - Stormwater Management Master Plan
year, 1-day and 100-year, 3-day design storm events. These values were established
for existing and future land uses, without incorporating recently completed projects,
projects under construction or future projects of the City's Capital Improvement Program
(CIP).
As part of this task, the previously developed XP-SWMM hydrologic/hydraulic models
prepared by DERM for the C-3, C-4, C-5, C-6, and C-7 basins were converted to the
current version of XP-SWMM (Version 2009-11.3, SP3). The basins were re -analyzed
with the current model version to have the most robust XP-SWMM hydrologic/hydraulic
modeling tools available for preparing the City's SWMMP. The results obtained from
the current model version were compared with the results documented by DERM in the
stormwater master plans for these basins to ensure that the results are comparable to
the previously calibrated and verified DERM models. In addition, the procedures and
assumptions implemented by DERM were used without further refinements or
modifications.
The results and information derived from the modeling activities under this task were
used to identity and rank problem areas in City basins located within the limits of the
C-3, C-4, C-5, C-6, and C-7 basins. Results from this task were also used to establish
peak stages, flows and flood durations baseline conditions for the 5-year, 1-day and
100-year, 3-day design storm events to quantify the incremental flood protection
benefits that will achieved from recently completed CIP projects, projects under
construction or future projects.
1.4 Identification & Ranking of Problem Areas
DERM established procedures and criteria, as part of their stormwater master planning
activities, to identify problem areas, rank problem those areas, and establish flood
protection level of service using the hydrologic/hydraulic modeling results for the 5-, 10-,
25-, 50- and 100-year design storm events. These procedures and criteria were
documented in Part I, Volume 3, "Stormwater Planning Procedures," March 1995 and
were applied by DERM to the C-3, C-4, C-5, C-6 and C-7 basins. In this methodology,
the ranking of flooding problem areas was related to a defined floodplain level of service
(FPLOS).
Additionally, the severity of flooding within each sub -basin was determined through the
calculation of a flooding problem severity score (FPSS), which was a function of five
"severity indicators" that were directly related to the FPLOS criteria and which were also
weighted using a specific weighing factor for each indicator and a depth of flooding
weighing component.
The ranking procedure developed by DERM was modified for this SWMMP update due
to a reduction in the number of design storm events analyzed and provided consistent
results. The additional parameters incorporated into the FPSS equation provided
additional items that were consistent with basin flooding and quantifiable using
XPSWMM result data and GIS.
1-4
January 2011 City of Miami Phase I - Stormwater Management Master Plan
The results and rankings were consistent with the results expected after discussions
with City of Miami staff. Flooding during the 5- and 100-year storm events are shown in
areas where flooding is typically experienced within the City of Miami. Low lying areas
clearly fell within the limits of the 5- and 100-year flood plains and properties, roadways,
and topographic areas were clearly quantified using these flood plains.
1.5 Hydrologic & Hydraulic Modeling of Existing & Future Condition Land
Uses with City Flood Protection Projects Completed, Under
Construction, & Under Design
The purpose of this task was to evaluate the flood protection benefits that have been
realized by the 31 stormwater improvement or flood protection projects completed and
under construction by the City within the C-3, C-4, C-5, and C-6 basins and the benefits
that may be realized by the four projects under design within the C-4, C-6, and C-7
basins.
The existing conditions XP-SWMM models were updated with the available stormwater
management project information to evaluate the flood protection benefits of projects
completed, under construction, and under design. Primary flood protection structural
components of these projects were represented in the XP-SWMM models, and the
results obtained "with projects" were compared to the results "without projects" during
the 5-year, 1-day and 100-year, 3-day design storm event simulations. All projects
completed or under construction were evaluated simultaneously and were not evaluated
individually, in combination, or with projects under design. Primary flood protection
structural components of all the projects under design were represented in the XP-
SWMM models including the projects completed or under construction to evaluate the
additional benefits that will be realized by these projects. The result data collected from
the various scenarios were used to create additional flood plain maps and revise the
sub -basin rankings for the City basins within the Phase I limits of this SWMMP update.
1.6 Identification of Future City Flood Protection Projects
The purpose of this task was to evaluate the stormwater infrastructure needs for the top
15 ranked sub -basins determined under the previous task and to devise flood protection
projects for each of the top 15 sub -basin in order to improve the flood protection level of
service for these critically low areas.
These projects were evaluated based on reducing the depth of flooding and identified
the total excess volume to be mitigated by these projects. Various stormwater
management systems were analyzed for their effectiveness at reducing the flood stages
during the greater intensity storm events. Peak stages from the model runs were then
correlated to a peak volume for each of the top 15 sub -basins and an extraction based
on these proposed systems was performed. The reduced volume could then be
interpolated to a given lower stage. The resulting lower stages were then correlated to
a reduction in flooded structures and roadways thus resulting a flood reduction
efficiency. Probable locations for these projects were also defined on a planning level
basis. Additionally, current stormwater quality and quantity requirements were also
detailed.
1-5
January 2011 City of Miami Phase I - Stormwater Management Master Plan
1.7 Ranking & Prioritization of Future City Flood Protection Projects &
Capital Plan
For this task, a prioritization methodology for ranking the future projects was defined.
This ranking methodology utilized the results of a benefit analysis weighed against the
probable construction costs of the improvements proposed at the sub -basin level. The
table below summarizes the results of the analysis and the ranking procedure
performed within this report.
Flood
Rank
Sub-
basin
Probable
Construction
Cost Total
Affected
Properties
Percentage
of Flooded
Properties
Cost per
Flooded
Property
Removed from
Flood Plain
importance
Factor
Revised
Ranking
13
C5-S5-3
$ 1,952,700
470
100
$ 4,154.68
1
1
7
006-N-11
$ 6,571,260
420
50
$ 15,645.86
1
2
1
CC6-N-12
$ 13,261,380
588
50
$ 22,553.37
1
3
4
C6-N-17
$ 12,794,430
415
50
$ 30,829.95
1
4
14
CC6-S-8
$ 2,580,960
201
50
$ 12,840.60
2
5
2
CC7-S-25
$ 5,094,000
255
25
$ 19,976.47
2
6
5
CC7-S-24
$ 4,618,560
187
25
$ 24,698.18
2
7
8
C6-S-12
$ 6,978,780
183
50
$ 38,135.41
2
8
11
C4-S-18
$ 628,260
109
25
$ 5,763.85
3
9
15
DA1-SE-2
$ 1,018,800
101
100
$ 10,087.13
3
10
12
C4-S-23
$ 1,721,772
141
50
$ 12,211.15
3
11
6
C4-S-17
$ 2,387,388
85
12
$ 28,086.92
4
12
10
CC7-S-26
$ 2,343,240
45
8
$ 52,072.00
4
13
9
CC4-S-21
$ 9,372,960
80
12
$ 117,162.00
4
14
3
CC7-S-21
$ 12,064,290
100
12
$ 120,642.90
4
15
The results of this analysis and the ranking will then be carried forward to Phase II of
the SWMMP in order to develop a comprehensive 5-year Stormwater Capital
Improvement Plan which will encompass the entire City of Miami and will use the most
recent Capital Improvement Plan budget allocations.
1-6
January 2011
City of Miami Phase I - Stormwater Management Master Plan
hNTRODU rION
2.1 General Background
The City of Miami (City) encompasses approximately 56 square miles (SM) of east -
central Miami -Dade County (County). Of this area, approximately 36 SM are located in
upland areas, while 20 SM are within the coastal waters of Biscayne Bay. The
mainland portion of the City (approximately 34 SM, excluding barrier islands) is located
within the C-3, C-4, C-5, C-6, C-7, DA-1/South Biscayne Bay and North Biscayne Bay
Basins or Watersheds. Figure 2-1 shows the City limits and the extent of the major
basins within the City, and Table 2-1 summarizes the area of these basins and total
area located within the mainland portion of the City.
Legend
Q CMy of Miami Limits
Major.Basins in City of Miami
rTc3
r C-4
C-5
C-6
LE C-7
t_-` _.! Biscayne North
Biscayne South
Island
Basin Boundaries (DERM)
li4
Figure 2-1 — Basins and Watersheds within the City of Miami
2-1
January 2011
City of Miami Phase I - Stormwater Management Master Plan
Table 2-1 - Basin and Watershed Areas within the City of Miami
Basin/Watershed
Total Basin Area
Square Miles (SM)
Total Area within the Mainland
Areas of the City of Miami
Square Miles (SM)
C-3
16.77
2.75
C-4
79.98
3.32
C-5
2.80
2.76
C-6
70.39
9.87
C-7
29.88
2.04
DA-1/South Biscayne Bay
7.99
7.93
North Biscayne Bay
63.79
5.35
TOTAL
271.60
34.02
The City last prepared a Stormwater Drainage Master Plan in 1986 for the main and
areas of the City, which excluded the barrier islands located within the City's limits In
order for the City to improve its National Flood Insurance Program (NFIP) Community
Rating System (CRS) classification from the current Class 8 rating to a Class 4 rating,
the current stormwater master plan would have had to have been updated within the
previous five years. Furthermore, to achieve a Class 4 rating, at least 50% of the
mainland portion of the City must be addressed in the update and the 100-year, 3-day
design storm event must be evaluated. By improving the CRS rating from a Class 8 to
Class 4, the City's residents would realize an additional 20% savings on their flood
insurance coverage premiums, which will be a substantial savings to the community and
confirms the need to update the current stormwater master plan.
In order to improve Miami -Dade County's CRS classification, the Miami -Dade County
Department of Environmental Resources Management (DERM) developed Stormwater
Management Master Plans for the main basins and watersheds within the County. To
standardize these master plans, DERM established detailed procedures for developing
and applying hydrologic/hydraulic computer models, establishing basin flood protection
levels of service, ranking and prioritizing problem areas, and ranking and prioritizing
flood protection projects. These procedures were documented in Part I and Part II,
Planning Criteria Procedures dated March 1995 and were approved by the Federal
Emergency Management Agency (FEMA) and Federal Insurance and Mitigation
Administration (FIMA) which oversee the NFIP. DERM used these procedures to
develop the Stormwater Management Master Plans for the C-3, C-4, C-5, C-6 and C-7
basins, which cover approximately 20.7 SM or 60% of the City's mainland area.
Based on the readily available information developed by DERM for 60% of the mainland
areas of the City, the City's Public Works Department determined that the most cost-
effective approach to update the City's Stormwater Management Master Plan was to
update it in two phases.
Phase I would include the mainland areas of the City encompassed within the C-3, C-4,
C-5, C-6 and C-7 basins (approximately 21 SM). This phase would be developed using
the existing hydrologic/hydraulic models and information developed by DERM for these
basins, to establish the City's current flood protection level of service and evaluate the
flood protection effectiveness of current and future City stormwater management
2-2
January 2011 City of Miami Phase I - Stormwater Management Master Plan
projects. The findings of Phase I would then be summarized in a Stormwater
Management Master Plan Report. The findings of this report will be used to develop a
five-year capital improvement plan in Phase 11 of the SWMMP update process that will
guide the City in implementing future projects in a systematic approach that will
maximize flood protection within the limited available funding. Once Phase I and Phase
II of the stormwater master plan are completed and adopted by the City Commission,
the City will then be able to apply for an improved NFIP CRS classification.
Phase II of the stormwater master plan update will include the areas covered by the
DA-1/South Biscayne Basin and North Biscayne Basin (approximately 13 SM). DERM
has not prepared stormwater management master plans for these basins. Therefore,
the City will be required to develop, calibrate, and verify hydrologic/hydraulic computer
models for these areas to be able to establish current and future flood protection levels
of services for these basins. The City will then use the previously described procedures
established by DERM and approved by FEMA and FIMA to develop these models and
perform the required analyses. As for Phase I, the findings of Phase II will be
summarized in a separate Stormwater Management Master Plan Report that will include
a comprehensive five-year capital improvement plan that will guide the City in
implementing future projects in a systematic approach for projects proposed in the
remaining portions of the City.
Phase I and Phase II of the Stormwater Management Master Plan (SWMMP) update
will address mainland areas of the City and will not include barrier island drainage
systems such as the Port of Miami area, Virginia Key, and other areas not part of the
City's mainland areas. Phase I and II will address flood protection levels of service of
primary drainage systems such as large conveyance storm drain systems and canals.
These phases will not address secondary drainage systems and minor localized
flooding. In addition, Phase I and Phase II will not address the water quality of
stormwater discharges from the City to receiving water bodies. However, the computer
modeling tools that will be implemented in Phase I and II have the capabilities to
perform these analyses and can be used in the future if required by the Florida
Department of Environmental Protection (FDEP) or other regulatory agencies.
To perform this update, A.D.A. Engineering, Inc. (ADA) was contracted by the City
under the Professional Services Agreement for Miscellaneous Civil Engineering
Professional Services dated February 7, 2008 (Contract No. 06-07-019) to complete
Phase I of the SWMMP. Phase I of the SWMMP was subdivided into tasks with a final
task consisting of the preparation of the final Phase I SWMMP (this report). The results
and findings of each of the primary tasks prepared as part of the Phase I SWMMP are
as follows:
O Data Collection and Evaluation
e Hydrologic and Hydraulic Modeling of Existing and Future Condition Land Uses
without City Flood Protection Projects
o Identification and Ranking of Problem Areas
O Hydrologic and Hydraulic Modeling of Existing and Future Condition Land Uses
with City Flood Protection Projects Completed and Under Construction and
Design
January 2011 City of Miami Phase I - Stormwater Management Master Plan
® Identification, Ranking and Prioritizing Future City Flood Protection Projects and
Flood Protection Projects Under Design
0 Phase I Stormwater Management Master Plan Report
Each of these tasks prior to the Phase. I Stormwater Management Master Plan Report
built upon one another and the findings were carried through to become the contents of
the Phase I Stormwater Management Master Plan Report Update.
2-4
January 2011
City of Miami Phase I - Stormwater Management Master Plan
3.0
DATA
C«'LLECTION
VALUATTION
The purpose of the Data Collection and Evaluation task was to request and/or collect
readily available information for the City of Miami, specifically within the C-3, C-4, C-5,
C-6, and C-7 basins. Although the focus of this task was to complete Phase I of the
Stormwater Management Master Plan, data was also requested for the DA-1/South
Biscayne Bay and North Biscayne Bay Basins which will be part of Phase II of the
Stormwater Management Master Plan that will be completed at a later date. Data was
requested and acquired from the various sources maintaining data that would support
the analysis, findings, and preparation of the individual technical memorandums for this
project as well as the final Phase I and Phase II Stormwater Management Master Plan
updates.
The collected data was cataloged, evaluated, and utilized as necessary to support the
analyses and preparation of the Stormwater Management Master Plan Reports for
Phase I and II. Water quality data was stored for potential future use, but it was not
processed or evaluated for this project. Topographic, geotechnical, or other specific
surveys were not included in the scope of this project.
Data collection activities required collecting data from the various entities with
jurisdiction over or that maintain data within the City's limits. Data was requested and/or
collected from the flowing entities:
o City of Miami
o Miami -Dade County
o South Florida Water Management District (SFWMD)
o National Oceanic and Atmospheric Administration (NOAA)
o Army Corps of Engineers (ACOE)
• United States Geological Service (USGS)
o Natural Resources Conservation Service (NRCS)
o Federal Emergency Management Agency (FEMA) - National Flood Insurance
Program
The following information was requested from Miami -Dade County which, besides the
City, has the most pertinent and applicable data needed to complete Phase I of the
SWMMP:
1. DERM stormwater master plan reports for C-3, C-4, C-5, C-6, and C-7
2. DERM stormwater master plan XP-SWMM models
3. GIS files supporting the XP-SWMM models
4. Digital Terrain Models (DTM) used to establish stage -storage relationships
5. Latest bare -earth LIDAR data for all sections within the City
6. Latest aerial images within the City
7. GIS shapefiles which include:
a. DERM basin delineations
b. Water bodies/canals
3-1
January 2011 City of Miami Phase I - Stormwater Management Master Plan
c. Land use (existing and future)
d. Soil types
e. Storm Sewer systems (wells, exfiltration trenches, pipes, outfalls, etc.)
f. Building footprints
g. Contaminated sites
h. Roadway Network by classification (local, arterial, and evacuation routes)
i. Lot/Right-of-Way lines and parcels
8. Flood complaint data within the City.
9. DERM Part I,, Planning Criteria and Procedures, Volumes 1 through 7, dated
March 1995
10.DERM Part II, Planning Criteria and Procedures, Volumes 1 through 5, dated
March 1995
In addition to this data request, the following information was requested from the City:
1. Latest Drainage Atlas Maps in hardcopy and GIS format
2. 1986 Stormwater Storm Drainage Master Plan
3. Current and future land use maps in GIS format
4. Current and future flood protection project conceptual or design plans in hard
copy and CADD format
5. Location and dimensions of needed drainage conveyance and control structures
(dimensions, invert elevations, materials, overflow elevation, etc.)
6. Rainfall, flow and stage data
7. Percolation test data
8. Drainage well capacity test results
9. Available building finish floor elevations
10.Tidal data
11. Pump station operation criteria and Togs
12. Location of evacuations routes
13. Construction unit cost data for recently constructed projects
14. Current operation and maintenance procedures and costs
15.Citizen flood/stormwater drainage complaints
16.Pertinent GIS data/coverages that will support development of the stormwater
master plans
Data collected for other entities was based on research of available web -data portals
available from these entities and ADA's own data catalogs. Data from these sources
were assessed on a case by case basis for pertinence to the development of both
Phase I and Phase II of the City of Miami's SWMMP.
3.1 City of Miami
The City of Miami is continuously improving their stormwater management systems.
Consequently, the hydrologic and hydraulic models collected from Miami -Dade County
may not necessarily reflect the improvements completed by the City in recent years
surrounding the development of the DERM master plans. As such, The City provided
ADA with a listing of 61 future, active, or completed projects that could potentially
impact the models under the existing and future conditions scenarios to be developed.
3-2
January 2011 City of Miami Phase 1- Stormwater Management Master Plan
Of the 61 projects, data was obtained for 44 projects. The data catalog presented in
Attachment A provides a listing of the City project data collected for incorporation into
the hydrologic/hydraulic models. The data catalog in Attachment A also includes a
section of pertinent City of Miami GIS data maintained by the City. This data includes a
digitized version of the City of Miami drainage atlas sheets, current and future land use
shapefiles, and a building footprint coverage, among others.
The City also provided information regarding recent stormwater pump station
improvements and modifications. A site visit was scheduled with City staff to discuss
the operating conditions used by the City to operate the pump stations.
Additionally, the City provided flood complaint data collected since 2005 and located by
street address which identifies localized areas showing recurring flood problems, scans
of the City's record grade atlas sheets and scanned sanitary sewer maps.
3.2 Miami -Dade County
Data from Miami -Dade County was acquired via two separate departments: DERM and
the Miami -Dade Enterprise Technology Services Department (ETSD). DERM provided
the various Stormwater Master Plan volumes for the C-3, C-4, C-5, C-6 and C-7 basins
as well as GIS data and XP-SWMM stormwater models for the different alternatives for
each respective basin. Attachment B provides a catalog of the digital data provided by
DERM.
DERM also provided a digital terrain model (DTM) in raster format and topographic
contours in shapefile format for the entire county in addition to the raw point data used
to create both items. These topographic points are LIDAR based bare -earth
topographic points processed by the County.
miamldade. ov
GIs seltseMces
vux
Si 1
...111 wa,rAttx.as
L nevn.AMEN, AREA%
11.01010.1
6FFiU'SKK'!(Mti'.G'.Tiil.f
FNFAn5 MNt 41.1
MNYLIIl,4 AYLAY
l,eMm.pAebhtmp
Figure 3-1 - Miami -Dade County GIS data portal
Additionally, ETSD provided GIS data which included shapefiles of County canals,
roadways, soils, hurricane evacuation routes, as well as the 2009 SID aerial images of
3-3
January 2011 City of Miami Phase I - Stormwater Management Master Plan
the County. The majority of Miami -Dade County's GIS data is also accessible via the
web, at the following location:
o Miami -Dade County GIS data portal
o http://gis.miamidade.gov/GISSelfServices/GeographicData/MDGeographic
Data.html
A screen capture of the Miami -Dade County GIS data portal is shown in Figure 3-1. A
catalog of the GIS data collected is also included in Attachment B.
3.3 South Florida Water Management District (SFWMD)
The SFWMD maintains an extensive water resources database, titled DBHYDRO,
which includes hydrologic, meteorologic, hydrogeologic and water quality data. The
data contained within DBHYDRO includes historical and current data for the 16 counties
governed by the SFWMD. In order to facilitate the access of this data, the SFWMD has
developed a browser accessible via the web, at the following location:
• Main DBHYDRO portal:
o http://www.sfwmd.gov/portal/page/portal/pg_grp_sfwmd_era/pg_sfwmd_er
a_dbhydrobrowser
o DBHYDRO Browser Menu for accessing all SFWMD data:
o http://my.sfwmd.gov/dbhydroplsgl/show_dbkey_info.main_menu
A screen capture of both the main DBHYDRO portal and the DBHYDRO Browser Menu
website are shown in Figure 3-2 and Figure 3-3.
The SFWMD also maintains a GIS data repository for all GIS data for the SFWMD - see
Figure 3-4. This GIS data catalog contains a shapefile with the location of all the
DBHYDRO stations where observations, samplings or monitoring are collected. This
shapefile is available via the web, at the following locations:
o GIS Data distribution site:
o http://my.sfwmd.gov/gisapps/sfwmdxwebdc/.
o DBHYDRO monitoring station shapefile:
o http://my.sfwmd.gov/gisapps/sfwmdxwebdc/dataview.asp?query=unq_id=
1588
January 2011
City of Miami Phase I - Stormwater Management Master Plan
'd[ Wow t09nrY @od'Inarlss Took
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SFWMD Home
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DSITYDRO Browser
Water Quality Monnonng
o- sFWMD Manila., locations
Reports
a Raquast Data
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nigaglpOsl6OeDao
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DBHYDRO is the South Florida Water Management District's corporate environmental database which
stores hydrologic, meteorologic, hydrogeologic and water quality data. This database is the source of
historical and up-to-date environmental data for the 16-county region covered by the District.
The DBHYDRO Browser allows you to search DBHYDRO, using one or more criteria, and to generate a
summery of the data from the available period of remrd. You Can then select dote sets of interest and
have the time series data dynamically displayed on your screen in tables or graphs. You can also
download data to your computer, for later use.
arr-i..naer, d-gai,try- 'adocca.socatNa Hn ne t lAo:sm,.nn
Figure 3-2 — Main DBHYDRO Portal
HYDRO Browser
bdi pew H¢ory @ooknets Iook
:IJny.nwwd.gm'1
Browser
I11
menu _
S U.0 t it r1 O H 1 0 A 4V A T F H M N A G C fif t. n'
DBHYDRO Browser Menu
Surface Water Data I❑ Meteorologic al Data I❑Ground Water Data
I Submit I
water QuaDty and OthPr SHmDIP Data
Hvdroaeolonir Data
Access Rv Station Name
Access By Site Name
Access By HvdroIoglr Rosin
Meta Data
Miscellaneous Items and Reports
Main Maonu I Homo I SFWMD HrlmP l lsar's (ioIidh I What's New I EIQ 1 Comments?
Figure 3-3 — DBHYDRO Browser Menu
3-5
January 2011 City of Miami Phase I - Stormwater Management Master Plan
O SFWMO • GIS Data Distribution . Morino Fireror.
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Figure 3-4 — SFWMD GIS Data Distribution Site
The location of the SFWMD monitoring stations within the City of Miami are shown in
Figure 3-5. This figure shows the location of all active and inactive monitoring station
locations. Additionally, some locations contain more than one type of monitoring station
and cannot be clearly presented in this figure.
Existing stormwater and environmental permitting information is also available via the
SFWMD ePermitting website. This website contains supporting documentation for
environmental resources permits (ERP) and applications submitted to and approved by
the SFWMD. These websites are as follows:
• Main SFWMD permitting portal:
o http://www.sfwmd.gov/portal/page/portal/levelthree/permits
• SFWMD ePermitting portal:
o http://my.sfwmd.gov/ePermitting/MainPage.do
In conjunction with the SFWMD permitting website, a GIS shapefile containing the
location and extent of the SFWMD ERP permit can be found at the SFWMD GIS data
repository mentioned previously — see Figure 3-6.
3-6
January 2011
City of Miami Phase 1 - Stormwater Management Master Plan
❑ WO
City of Miami Limits
Basin Boundaries (DERM)
Figure 3-5 — SFWMD Monitoring Stations
Additionally, the SFWMD data repository is a viable source for additional data that is
often directly available from other sources such as land use, soils, aerial imagery, etc.
Although this data may not be maintained regularly, this data may be used if alternate
sources are not accessible.
3-7
January 2011 City of Miami Phase I - Stormwater Management Master Plan
Figure 3-6 — SFWMD ERP Permit locations within the City of Miami
3.4 National Oceanic & Atmospheric Administration (NOAA)
Tide data is available from NOAA. NOAA monitors, assess, and distributes tide, current
water level, and other coastal oceanographic data via their Center for Operational
Oceanographic Products and Services (CO-OPS). NOAA's data is accessible via the
web, at the following location:
• Main NOAA CO-OPS portal:
o http://tidesandcurrents.noaa.gov/
• NOAA's Observational Data Interactive Navigation (ODIN) site for station data:
o http://tidesandcurrents.noaa.gov/gmap3/
GIS data is also available from NOAA. GIS data for the NOAA stations can be obtained
from the following location:
• NOAA GIS portal:
o http://coastalgeospatial.noaa.gov/data_gis.html
A screen capture of the NOAA's station data access site nearest to the City as well as
the main GIS data access site are shown in Figure 3-7 and Figure 3-8, respectively. _
3-8
January 2011
City of Miami Phase I - Stormwater Management Master Plan
The Virginia Key station is the closest monitor station to the City of Miami and is the
only station within the county. The actual daily data will be collected as necessary
depending on the needs of the calibration task to be performed as part of the Phase II
SWMMP development.
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il Geography Description
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al Assessment
As (CAF)
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Program (Alta.!/sancatines noaa.aav/I.brarr/imast Ais,htmll
!nee Sta00ns -.
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Oroanoorephic Products end Services
(hrtp /nidesendonretm.naaa.pav/).
Ls naa.n «..., --...._,-_ iTh dataset _t ,d b[ NOAA N 4onel C Me for Coastal'
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Figure 3-8 — NOAA GIS data site
3-9
January 2011 City of Miami Phase I - Stormwater Management Master Plan
3.5 United States Army Corps of Engineers (ACOE)
In July, 2009, the USACE prepared an Engineer Circular which discussed future
potential sea level changes and their effects on managing, planning, engineering,
designing, constructing, operating, and maintaining USACE projects and systems of
projects in coastal regions. This document references various locations in South Florida
which correlate closely to the City of Miami, making this document pertinent to the City
due to the City's location adjacent to the ocean and tidal waters.
This document is available via the web at the following location:
Y USACOE Main Engineer Circular Portal:
o http://140.194.76.129/publications/eng-circulars/
e USACOE Sea Level Change Engineer Circular (EC 1165-2-211)
o http://140.194.76. 129/publications/eng-circulars/ec1165-2-211/ec1165-2
211.pdf
3.6 United States Geological Service (USGS)
The USGS maintains a network of groundwater wells that are monitored continuously in
cooperation with the SFWMD. Groundwater wells are located throughout the City and
County and, in some cases, historical data for wells that have been retired is also
available. Groundwater stage data for the various wells throughout the City can be
obtained from the following website:
o Main USGS data portal:
o http://www.sflorida.er.uscts.00v/
• Data access site:
o http://www.sflorida.er.usos.gov/ddn data/index.html
The data is provided in trended and de -trended or without trend removal. This accounts
for the historical drop in the groundwater levels within the region. The data access site
is shown in Figure 3-9.
3-10
January 2011
City of Miami Phase I - Stormwater Management Master Plan
k',)Trend,Cnmpenuted Overview of Rea.Ilrnei at—leyoLnionimr Sit :an,,SnDtry Fjlondp;iA qua f rergi
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Summary of Conditions
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PROVISIONAL GRAFT— Subject to Revision
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Figure 3-9 — USGS groundwater well data site
3.7 Natural Resources Conservation Service (NRCS)
The NRCS is a federal agency under the United States Department of Agriculture
(USDA) which performs and maintains soil survey information for the United States.
Through the USDA's Geosptial Data Gateway site, soil maps and data is available
online for more than 95 percent of the nation's counties — see Figure 3-10. The site is
updated and maintained online as the single authoritative source of soil survey
information and can be accessed via the web
• Main Geospatial Data Gateway Portal:
o http://datagateway.nrcs.usda.gov/GatewayHome.html
Additional data is available through this system including digital ortho imagery, digital
elevation models, and other cultural and demographic data.
3-11
the one stop source ai
natural resources data
January 2011 City of Miami Phase I - Stormwater Management Master Plan
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Figure 3-10 — USDA's Geosptial Data Gateway site
3.8 Federal Emergency Management Agency (FEMA)
As stated by FEMA in the National Flood Insurance Program (NFIP) Description
document:
"The U.S. Congress established the National Flood Insurance Program
(NFIP) with the passage of the National Flood Insurance Act of 1968. The
NFIP is a Federal program enabling property owners in participating
communities to purchase insurance as a protection against flood losses in
exchange for State and community floodplain management regulations
that reduce future flood damages. Participation in the NFIP is based on an
agreement between communities and the Federal Government. If a
community adopts and enforces a floodplain management ordinance to
reduce future flood risk to new construction in floodplains, the Federal
Government will make flood insurance available within the community as a
financial protection against flood losses. This insurance is designed to
provide an insurance alternative to disaster assistance to reduce the
escalating costs of repairing damage to buildings and their contents
caused by floods."
Additionally, the Community Rating System (CRS) is described as follows in the same
document:
3-12
January 2011 City of Miami Phase I - Stormwater Management Master Plan
"The NFIP's Community Rating System (CRS) provides discounts on flood
insurance premiums in those communities that establish floodplain
management programs that go beyond NFIP minimum requirements.
Under the CRS, communities receive credit for more restrictive
regulations, acquisition, relocation, or flood -proofing of flood -prone
buildings, preservation of open space, and other measures that reduce
flood damages or protect the natural resources and functions of
floodplains."
The NFIP Flood Insurance Manuals were collected from the following FEMA website:
• FEMA Flood Insurance Manual portal:
o http://www.fema.gov/business/nfip/manual.shtm
These manuals provide direction with regards to improving the City's CRS rating and
thus increasing the discount available to City residents through NFIP. These manuals
also provide guidelines and requirement for stormwater management master plans to
improve CRS ratings.
3.9 Data Evaluation
The data collected from the City of Miami and Miami -Dade County was evaluated to
define the completeness and viability of the data as well as to identify the pertinent
items that would be applicable to this stormwater master plan update. The following
subsections detail the significant components of the data collected and their potential
role is the development of this stormwater master plan update.
3.9.1 Miami -Dade County DERM Data
The data collection effort associated with this task was primarily focused on collecting
the necessary data to ensure that Phase I of the SWMMP can be completed. The most
important data collected for Phase I of the SWMMP was collected from DERM and the
City. In addition, the most important data collected from DERM included the existing
and future land use conditions hydrologic/hydraulic models prepared to support
development of the Stormwater Master Plans for the C-3, C-4, C-5, C-6 and C-7 basins.
The Stormwater Management Master Plan Reports for these basins provide the
background, assumptions, and approach on how these models were developed. These
reports and their respective existing and future XP-SWMM hydrologic/hydraulic models
will provide the basis for the hydrologic/hydraulic modeling activities required as part of
Phase I of this SWMMP.
The data collected by DERM was evaluated, and an initial review was performed on the
XP-SWMM models and the supporting documentation. The following was noted
regarding each model developed for these basins:
• The C-3/C-5 XP-SWMM model is based on the Version 9.08 engine.
• The C-4 XP-SWMM model is based on the Version 8.87 engine.
• The C-6 XP-SWMM model is based on the Version 9.28 engine.
3-13
January 2011 City of Miami Phase I - Stormwater Management Master Plan
e The C-7 XP-SWMM model is based on the Version 9.10 engine.
The DERM models were developed and analyzed under the 5-, 10-, 25- , 50- and 100-
year events. One of the requirements to be able to approach a CRS Class 4 rating is
that the stormwater master plan must address at least 50% of the mainland portion of
the City and the 100-year design storm event must be evaluated. Furthermore, the City
requested that the DERM basin models be run under the 5-year, 1-day storm event in
order to establish basin specific flood protection levels of service per City ordinance.
For this reason, the analysis for this SWMMP update will focus on the 5- and 100-year
events.
It should be noted that upon initial review of the supporting documentation, it appears
that the existing and future land use conditions varied by a small amount due to the
highly urbanized and developed nature of most sub -basins. Due to this condition, a
future conditions model was not developed by DERM for the C-3, C-5 and the C-7
basins. Additionally, although a similar situation may be present in the areas
encompassed by the City in the C-4 and C-6 basins, existing and future condition
models were prepared, and analyses were performed using both conditions for each
design event.
The subbasin delineations for some of the DERM master plans in the areas within the
City of Miami were developed using the City of Miami subbasin delineation. Upon initial
review, in some locations, the DERM subbasins appear to follow the general extent/path
of the City of Miami basins, but there is a clear deviation between the two delineations.
In some cases it appears that smaller basins were merged and/or revised to follow
topographic features. Both these delineations diverge significantly from the 1986 City of
Miami Stormwater Drainage Master Plan subcatchment delineations. For this project,
the DERM delineations were used in agreement with the DERM models. A map
showing the City of Miami and DERM master plan basin delineations is available in
Attachment C.
Upon evaluation of the DERM models, it was noted that systems were simulated based
on their main interbasin components and were classified into three types of stormwater
management systems — positive, exfiltration/infiltration, and hybrid. Positive systems
were broken down into their main components and were based on their physical
characteristics based on the best available data. Exfiltration/infiltration and hybrid
systems were not modeled physically, but were simulated using an extraction method
based on the Horton Infiltration methodology included in the XP-SWMM model.
The Horton infiltration parameters were designed to provide total infiltration up to the
5-year, 24-hour storm volume (6.5 inches) and allow total runoff beyond this volume.
This maximum infiltration volume was decreased to 5.0 inches (as recommended by
DERM) as it was assumed that due to the age and lack of maintenance of the
exfiltration trench systems, that they are no longer able to control the 5-year, 24-hour
storm volumes. The following infiltration parameters were used to simulate the operation
of exfiltration trenches in the XP-SWMM model:
'L
3-14
January 2011 City of Miami Phase I - Stormwater Management Master Plan
• Maximum Infiltration Rate — 4.0 in/hr
• Minimum Infiltration Rate — 0.25 in/hr
• Decay Rate of Infiltration — 0.00115 sec-1
• Maximum Infiltration Volume — 5.0 inches
• Impervious Area Depression Storage (IDS) - 0.02 inches
• Pervious Area Depression Storage (PDS) — 0.05 inches
• Impervious Area Manning's Roughness Coefficient (IMPN) — 0.04
• Pervious Area Manning's Roughness Coefficient (PERVN) — 0.2
• Percent of DCIA without Detention Storage (PCTZER) — 25
• Horton Regeneration Factor — 0.003
Additionally, although all the DERM basins were modeled independently, all of the
DERM basins have some level of interconnectivity between the basins. Major
connections between the main basins were simulated physically and implemented as
boundary conditions during the development of the various master plans. The basin
interconnectivity, based on the DERM master plans is as follows:
• C-3 Basin interconnects with the C-2 and C-5
• C-4 Basin interconnects with the C-2, C-3, C-5 and C-6
• C-5 Basin interconnects with the C-3, C-4 and C-6
• C-6 Basin interconnects with the C-4, C-5, C-7
• C-7 Basin interconnects with the C-6 and C-8
Various assumptions dictated how the boundary conditions were applied and this
interconnectivity was explored further. As outlined in the scope of work for Phase I of
the SWMMP, the boundary conditions and the basin interconnectivity was not
reevaluated and was maintained as provided by DERM.
DERM also established procedures and criteria, as part of their stormwater master
planning activities to identify problem areas, rank problem areas, and establish flood
protection levels of service using the modeling results for the 5-, 10-, 25-, 50- and 100-
year design storm events. These procedures and criteria are documented in Part I,
Volume 3, "Stormwater Planning Procedures," March 1995 and were applied by DERM
to the C-3, C-4, C-5, C-6 and C-7 basins. In this methodology, the ranking of flooding
problem areas were related to a defined floodplain level of service (FPLOS).
The severity of flooding within each sub -basin was determined through the calculation
of a flooding problem severity score (FPSS), which is a function of five "severity
indicators" that are directly related to the FPLOS criteria described above. Each of
these indicators has also assigned a "weighing factor" (WF), which is related to the
relative importance of the flooding severity indicator. The severity indicators are also
rated by an exceedance (E) value.
Given the definitions for the flooding severity indicators (NS, MER, BM, MMAS, and
MCLRS - described later), WF and E, the FPSS for each sub -basin is calculated using
the following formula, where E() through Eta) relates to the degree of exceedance for
each of the five severity indicators:
3-15
January 2011 City of Miami Phase I - Stormwater Management Master Plan
FPSS = [4 x E(;) x NS] + [4 x E(;;) x MER] + [3 x E(;;;) x BM] +
[2 x E(;,) x MMAS] + [1 x E(,) x MCLRS]
Once the severity is calculated, the score for each sub -basin can be tabulated, and the
sub -basin with the highest FPSS is given a ranking value of 1. Subsequent FPSS
scores are then given ranking values of 1 through X. Sub -basins with equivalent FPSS
are given the same ranking value. This approach yielded the basins with the highest
flooding problems based on a mathematical formulation.
The actual flood protection level -of -service (FPLOS) provided within a particular sub -
basin is dependent upon the number of FPLOS criteria that have been met, as defined
previously. Also, DERM established a FPLOS rating by assigning a letter grade. The
City SWMMP will only focus on the 5- and 100-year design storm events. Therefore,
these methodologies were revised.
3.9.2 City of Miami Data
With regards to the City of Miami Data, initially, based on the scope of work for Phase I
and Phase II of the SWMMP, improvements to the major components of the City's
stormwater management system were to be based on the City's listing of 23 major
stormwater management projects constructed, under construction, or under design.
This initial list was later appended after NTP to include a number of projects which were
also identified to be providing a potential benefit to the City's stormwater management
systems. The City's Public Works Department identified 38 additional projects that have
been constructed and were not included in the initial CIP list of projects bringing the
total project count to 61. Of the 61 projects listed, project information was provided for
44. Attachment A provides a complete listing of the projects requested, collected, or
omitted for lack of data.
The project data for the 44 projects were evaluated and their inclusion in the SWMMP
was dependent on the type of system implemented and the overall function of the
system. The DERM models do not represent the minor components within a given
stormwater management system. Because of this, minor improvements that would only
provide a localized benefit within a sub -basin and are primarily associated with
conveyance within the sub -basin rather than exfiltration or conveyance out of the sub -
basin, were not be included because the benefit would not be realized in the models.
The City's 1986 Storm Drainage Master Plan was also reviewed to determine if there
were specific contents in the master plan that would streamline development of Phase I
and Phase II of the SWMMP. Review of the drainage master plan indicated that the
entire City was subdivided into 52 separate subareas, and these subareas were
grouped into 22 subcatchments. The subcatchments were further grouped into 10
zones. The subdivision was based on sporadic topographic information supplemented
by available spot elevations. The drainage master plan also identified key hydrologic
parameters, flow direction and major conveyance systems for each subcatchment.
Review of the subcatchment boundaries showed that the boundaries do not correlate
well with the DERM sub -basin delineations for the DERM watersheds (C-3, C-4, C-5, C-
January 2011 City of Miami Phase I - Stormwater Management Master Plan
6 and C-7) located within the Phase I SWMMP limits and are too coarse (100 to 900
acres) to support development of Phase I of the SWMMP. However, subcatchment
information could be beneficial in delineating sub -basins for Phase II of the SWMMP
update.
As part of the 1986 drainage master plan, capacity analyses were performed for the
Little River Canal, Miami River, Seybold Canal, Wagner Creek, Tamiami Canal, Comfort
Canal and the Lawrence Waterway using the HEC-2 model, with limited canal cross
sections available at the time. The information developed as part of this effort will not
be useful in the development of Phase I of the SWMMP, because DERM used
extensive and current canal cross sections for the canals located within the Phase I
limits. This information could be used for development of Phase II hydraulic models to
supplement canal cross sections information if not available. The drainage master plan
also used a simplified procedure to estimate the pipe capacity of the primary
conveyance systems within the City. This simplified approach used a steady state
methodology using Manning's equation. This information will not be usable for Phase .I
and Phase II of the SWMMP, because dynamic analyses will be performed using the
XP-SWMM model, which will yield more representative stage, flow, and volumetric
results. The drainage master plan also included groundwater .analyses areas where
exfiltration systems can be used and areas where they will not be effective. The
analysis could be useful in indentifying exfiltration systems proposed for Phase I and
Phase II of the SWMMP.
The 1986 drainage master plan culminated in a 12-year storm drainage program that
included numerous projects to improve the flood protection within the City and quality of
stormwater discharges from the City. Total cost of the program was projected at $267
million in 1986 dollars. Some of these projects have already been implemented by the
ongoing City's Capital Improvement Program. The benefits of these projects were
assessed with the dynamic XP-SWMM hydraulic model, as part of Phase I and Phase II
SWMMP. Phase I and Phase II of the SWMMP also identify the priority of the pending
capital projects to maximize the benefits of the limited funding for flood protection
projects.
3.10 Data Collection Conclusion Recommendations
Sufficient data was collected to proceed with the development of Phase I of the
Stormwater Management Master Plan update. As previously stated, as part of the data
collection effort for Phase I of the SWMMP, data was also collected for Phase II to
streamline future data collection efforts. Evaluation of data collected also indicated that
there is adequate data to complete Phase II of the City of Miami SWMMP update.
However, there should be a data collection effort as part of Phase II to collect additional
data not available at the time of this writing or to obtain more current data than was
available.
January 2011
City of Miami Phase I - Stormwater Management Master Plan
4.1 Miami -Dade DERM XP-XWMM Models
To support the development of the stormwater management master plans for the C-3,
C-4, C-5, C-6 and C-7 basins, DERM implemented previously established procedures
for developing, calibrating and verifying hydrologic, hydraulic and water quality models
using the XP-SWMM computer model. These procedures were documented in Part I,
Volumes 2 and 3, of the "Stormwater Planning Procedures" document, dated March
1995 which was obtained from DERM and were used by DERM to develop existing
conditions XP-SWMM models for each basin, using the 2005 Miami -Dade .County land
use data. These models were calibrated and verified using available measured rainfall,
stage, and flow data recorded for extreme storm events. Once the models were
calibrated and verified, the models were adjusted to perform design event simulations
(production runs) for the following design storm events:
O 5-year, 1-day
O 10-year, 1-day
O 25-year, 3-day
O 50-year, 3-day
O 100-year, 3-day
For some basins, the existing conditions models were further revised to incorporate
2025 land use data. Once revised, the future land use condition models were also
simulated for these five design storm events. DERM compared the modeling results
between existing and future land uses and found little to no difference between the
existing and future land use models. Therefore, DERM has decided not to evaluate
future land uses in further refinements of these master plans.
4.2 General Hydrologic/Hydraulic Model Setup Approach & Methodologies
The XP-SWMM model is a one-dimensional, node -link, hydrodynamic model that was
originally derived from the EPA SWMM model. XP-SWMM offers substantial
enhancements over the EPA SWMM model, including a more refined and robust
mathematical engine and graphical user interface that has extensive inter -phase
capabilities with GIS and AutoCAD. The new version of XP-SWMM also has the
capability of performing two-dimensional analyzes. However, DERM did not perform
two-dimensional analyses as part of any of the County's stormwater master plans.
XP-SWMM is also comprised of three mathematical engines or blocks: Runoff Block,
Extran Block, and Sanitary Block. The Runoff Block is used to generate hydrographs
using either of the following well -accepted hydrologic methods:
January 2011 City of Miami Phase I - Stormwater Management Master Plan
o EPA Runoff
o Laurenson
• SCS Hydrology
o Nash
• Synder
o Clark
o Santa Barbara Unit Hydrograph
o Rational Formula
The Runoff Block can also be used .to generate pollutant loading estimates from a
defined sub -basin and can simulate groundwater infiltration from each sub -basin and
specified points along the canal system. These connections generate groundwater
hydrographs that are added to the surface runoff of a defined canal reach. These
capabilities were used by DERM to account for groundwater contribution from close
basins to the canal network, which can be substantial due to the highly transmissive
soils found in Miami -Dade County.
The Extran Block is used to dynamically route the hydrographs generated with the
Runoff Block using the Saint-Venant dynamic wave equations. XP-SWMM gives the
user the flexibility to solve the full dynamic wave equation or the simplified kinematic
wave equation. Finally, the Sanitary Block is used to dynamically route pollutant
generated in the Runoff Block and can simulate Best Management Practices (BMPs)
performance based on pollutants removal capabilities in the stormwater management
system. DERM implemented the Sanitary Block in the development of all stormwater
management master plans to estimate annual pollutant loadings from all basins within
Miami -Dade County. However, the Sanitary Block will not be used in the development
of the City's SWMMP, because this master plan will primarily focus on the flood
protection level of service within the City.
4.2.1 Hydrology Model Setup (Runoff Block)
In the development of the XP-SWMM models for the C-3, C-4, C-5, C-6 and C-7 basins,
DERM implemented the EPA Runoff Method, which is a non -linear reservoir runoff
routing method for generating runoff hydrographs. The first step in developing the
Runoff Block parameters is to delineate sub -basins within the watershed. DERM
predominantly used light detection and ranging (LiDAR) elevation data developed and
confirmed by United States Corps of Engineers (ACOE) to develop digital terrain (DTM)
models for each basin. LiDAR based data provided the most extensive coverage of
topographic data available and was the only elevation data used in most areas, various
sets of topographic point elevations were also incorporated in the development of the
DERM DTMs and included WASD, Woolpert, and SRM survey elevations. All
topographic data was provided by the County.
In order to minimize the projection of the bare -earth surface to "false elevation" points
attributed to buildings, points that resided within the County's building coverage were
removed from the topographic data point sets. Additionally, points with elevations that
did not reasonably coincide with the elevation range of neighboring points, were also
omitted. The resulting surfaces within these point gaps were the result of an
January 2011 City of Miami Phase I - Stormwater Management Master Plan
interpolation process that is carried out by the software used and thus a "bare earth"
equivalent surface was achieved.
Similarly, the point data was filtered using GIS to remove all points falling within the
County's water body coverage to account for the available storage below the water
elevation present at the time of the LIDAR data collection.
Sub -basin delineations were developed along the high ridge lines within the major basin
areas using the newly developed DTMs. Additional delineation lines were developed
from canals, major roads, railroads and other natural or man-made high elevation
breaks. DERM also used the City of Miami sub -basin delineation to assist in the
development of the sub -basin delineation within the City, but the actual delineations
were not used explicitly, and many City sub -basins were grouped into larger sub -basins
or refined as necessary.
With regards to the sub -basin nomenclature, DERM used a uniform naming system
which was implemented in all the stormwater management plans for the County. The
naming convention applicable to all basins can be summarized as follows, using the C-6
basin as an example:
o Tributary canals to the C-6 canal are named N#-C6 or S#-C6 depending on the
location of the canal in reference to the C-6 canal (north or south). Canals are
sequentially numbered starting from the most western canals. The canal
nomenclature is used to define the sub -basin names of those basins draining to
tributary canals as described below.
o Sub -basins that drain directly to the C-6 are named C6- #
o For the sub -basins located north of the C-6 canal: C6-N-#
o For the sub -basins located south of the C-6 canal: C6-S-#
a Other sub -basins are named according to the canal reach that they drain into
followed by the letter N, S, E, or W depending on what side of the canal the basin
is located. For example, sub -basin N4-C6-W-1 is a sub -basin that drains into the
N4-C6 canal and is the first sub -basin located west of the tributary canal.
o All sub -basins draining into a canal are numbered in increasing order from
upstream to downstream.
o Closed sub -basins, i.e., not draining directly to a canal, are preceded by the letter
C for "closed". For example, CC6-N-12 is a closed sub -basin north of the C-6
canal and is just downstream of CC6-N-11.
In the Runoff Block, XP-SWMM allows up to five (5) sub -catchments for each sub -basin.
As part of DERM's Stormwater Planning Procedures, each sub -basin was sub -divided
into at least two sub -catchments each corresponded to one of the following conditions:
G Areas with stormwater BMPs like exfiltration trenches, large swale systems or
hybrid systems
• Areas with only positive drainage systems
Areas with BMPs were simulated using the Horton Infiltration Solution assuming no
directly connected impervious areas (DCIA). The Horton infiltration parameters were
January 2011 City of Miami Phase I - Stormwater Management Master Plan
used to provide total infiltration up to the 5-year, 24-hour storm volume (6.5 inches of
total infiltration) and allow total runoff beyond this volume. This maximum infiltration
volume was decreased by DERM to 5.0 inches, as it was assumed that the exfiltration
trench systems are no longer able to control the 5-year, 24-hour storm volumes due the
age of the majority of the systems in place. The following Horton infiltration parameters
were used to simulate the operation of exfiltration trenches, swales, and hybrid systems
in the XP-SWMM model:
• Maximum Infiltration Rate — 4.0 in/hr
• Minimum Infiltration Rate — 0.25 in/hr
• Decay Rate of Infiltration — 0.00115 sec-1
• Maximum Infiltration Volume — 5.0 inches
• Impervious Area Depression Storage (IDS) - 0.02 inches
• Pervious Area Depression Storage (PDS) — 0.05 inches
• Impervious Area Manning's Roughness Coefficient (IMPN) — 0.04
• Pervious Area-Manning's Roughness Coefficient (PERVN) — 0.2
• Percent of DCIA without Detention Storage (PCTZER) — 25
• Horton Regeneration Factor — 0.003
Areas with no BMPs were simulated using the Green-Ampt infiltration method. The
following infiltration parameters were used to simulate sub -catchment infiltration using
the Green -Amp method:
o Average Capillary Suction (SUCT) - 4 inches
• Initial Moisture Deficit (SMDMAX - 0.30 for sand under wet initial conditions.
• Saturated Hydraulic Conductivity (HYDCON) - 0.8 in/hr.
• Impervious Area Depression Storage (IDS) - 0.02 inches
• Pervious Area Depression Storage (PDS) - 0.2 inches
• Impervious Area Manning's Roughness Coefficient (IMPN) — 0.04
• Pervious Area Manning's Roughness Coefficient (PERVN) — 0.3
• Percent of DCIA without Detention Storage (PCTZER) — 25
These values were the initial, uncalibrated parameters used which were then modified
as needed during the calibration process to match measured historical stage and flow
data.
DERM utilized GIS data and tools to establish the other critical Runoff Block sub -
catchment parameters such as Catchment Area, DCIA, Width, and Slope. The methods
are described as follows:
• Catchment Areas were determined by the areas available from the polygons in
the sub -basin delineation GIS shapefiles.
o DCIAs for areas represented by the Green-Ampt infiltration method were
established based on prior procedures developed by DERM to correlate DCIAs
to land use. As part of these procedures, DERM consolidated the approximate
100 land uses defined throughout the County into 23 major classifications for
hydrologic evaluation. DERM established DCIA values for the 23 classifications
January 2011 City of Miami Phase 1 - Stormwater Management Master Plan
based on representative measured values. These values were used to
established weighted DCIAs based on the extent of the specific land uses within
each sub -catchment.
• The basin Width was calculated using the basin area divided by the length of the
bordering canal. The Width of closed sub -basins was estimated as the square
root of the sub -catchment area.
• The Slope was established based on the average overland slope of the sub -
basins using GIS tools and the DTM.
The DCIAs, width, and slope were also modified during the calibration process.
4.2.2 Hydraulics Model Setup (Extran Block)
The .Extran Block .uses nodes and links to define the hydraulic network - in XP-SWMM
nodes are referred to as junctions and links as conduits. For each basin, DERM coded
the Extran Block hydraulic parameters for the primary and major secondary drainage
systems using available as -built plans, permit data, and collected field survey data.
More emphasis was placed on unincorporated areas of the County, because the
purposes of these models were to implement projects with County funding.
The Junction names were set to the same name as the sub -basin name, where
applicable. For junctions with no sub -basin association, the same nomenclature
procedure was implemented for the junction name as for the sub -basin names.
In general, there were several types of conduits used in the C-3, C-4, C-5, C-6, and C-7
basin Hydraulics models:
• Circular conduits for the cross drains and stormwater pipes
• Rectangular conduits for cross drains, stormwater pipes and bridges
• Rectangular weirs and orifices for control structures
• Time varying orifices to simulate control structure gate opening and closing
• Pumps for control structures
• Natural channels for the open channel reaches and overland flow connection
between adjacent basins
With regards to the nomenclature for conduits, the first three letters define the canal
represented by the conduit, and the remaining characters refer to the location of the
conduit. For conduits representing cross drain conduits, the names begin with either a
U, E, or B to indicate whether the structure is a culvert, an equalizer or a bridge,
respectively. The numbers used for culverts and equalizers were based on the
nomenclature used by DERM when these structures were surveyed.
Sub -basin stage -storage relationships were developed using GIS and the DTMs created
for each sub -basin. Overland connectivity between adjacent sub -basins were simulated
using natural channel conduits. Channel cross sections were obtained using GIS and
the DTMs. The initial groundwater depth of each junction was established based on the
average October groundwater elevations. DERM used a variable value for some basins
4-5
January 2011 City of Miami Phase I - Stormwater Management Master Plan
and an average -constant value for others. The actual values used for each basin are
described later in this report.
The endpoints junctions of each model network were simulated as outfall junctions and
define the boundary conditions of the model. The outfall junctions used by DERM for
the basins within the City include Free Outfall, Fixed Backwater, Tidal Series, Stage -
Discharge relationship, or Time -Stage relationship. One set of boundary conditions
were used for calibration based on measured data and another set was used to
simulate design storm event conditions. The specific boundary conditions and
assumption used for each basin are described and summarized later in this report.
4.2.3 Model Calibration & Verification
After each model was set up, DERM calibrated and verified each model using large
historical rainfall events. Several recorded rainfall events were identified and used, but
for all basins, DERM used both Hurricane Irene (October 1999) and the "No Name
Storm" (October 2000) as either a calibration or verification event. For some basins,
verification was performed by running the calibrated model for the storm events (5-, 10-,.
25-, 50-, and 100-year). The resulting peak flows at the structures were then compared
to (Log -Pearson Type III) statistical analysis of historical storm events.
The real unknown for calibrating a stormwater model is typically the resultant of the
runoff hydrograph which is composed of surface runoff and groundwater flow. The
physical hydraulic features of the systems are generally known, and with relatively slow
velocities in the canals, the model friction factors and roughness factors are not
significant in most of the model conduits (with the exception of the gates and undersized
culverts). Therefore, DERM focused in the calibration process on adjusting some key
sensitive hydrologic parameters such as sub -catchment width and slope. The Horton
infiltration parameters were not manipulated because they were set to represent
infiltration/exfiltration BMPs at a maximum infiltration depth of 5 inches. The Green-
Ampt sub -catchments infiltration parameters were manipulated to achieve the desired
runoff hydrograph. In some cases the control structure operations were manipulated if
accurate operation data was not available, to match observed flow volume and stage
conditions.
4.2.4 Model Production/Design Storm Event Runs
Once each basin model was calibrated and verified, the rainfall data and boundary
conditions of the models were modified to represent design storm event conditions
versus measured or observed data. Because many of the basins modeled by DERM
cover such a large aerial extent, SFWMD design rainfall depths were used for each
region of the model to represent the design rainfall depth for that portion of the model.
For design storms with a 1-day duration, the Type II, SCS Florida Modified distribution
was used, and the SFWMD 3-day distribution was used for the 3-day design storms.
DERM also modified the models to include major improvements in the basins that
occurred after the calibration and verification events. Some of these improvements
included canal widening and dredging activities, modification or addition of new culverts
4-6
January 2011 City of Miami Phase I - Stormwater Management Master Plan
and improvements to major control structures. DERM then developed separate models
for the 5-, 10-, 25-, 50- and 100-year design storms, because of the wide variation of
rainfall depths throughout the basin. Each of the models were then executed with
existing land uses, and in some cases with future land uses, to obtain the each basin
hydrologic and hydraulic responses for the following design storm events:
O 5-year, 1-day
O 10-year, 1-day
O 25-year, 3-day
O 50-year, 3-day
O 100-year, 3-day
The peak stages, flows and flood durations were then reported for each design storm
event, in relation to each junction and conduit in the models. For the development of the
City's SWMMP, only the 5- and 100-year design event models will be used.
DERM also performed the continuous simulations modeling using Dry, Average, and
Wet yearly rainfalls. The continuous simulation modeling was performed to obtain
annual runoff volumes needed to estimate annual pollutant loading and distribution for
each basin. This information will not be used in the development of the City's SWMMP,
because this master plan will primarily focus on flood protection level of service for the
areas within the City located in the C-3, C-4, C-5, C-6 and C-7 basins.
Sections 4.4 through 4.8 define specific model set, calibration, verification, and
production runs conditions and assumptions for each of the basins located within the
City and modeled by DERM.
4.3 DERM to City of Miami Basin Comparison
The City of Miami has sub -basin delineations in their stormwater drainage atlas sheets
which are part of the GIS database for the City (feature class MS4_Basin_Areas).
These sub -basins appear to be mostly based on the infrastructure data shown on the
stormwater atlas sheets maintained by the City. Although these atlas sheets are not
maintained on a regular basis, the majority of the systems shown on these maps exist
today. Because of this, DERM, in most cases, used these sub -basins as a preliminary
basis for the development of the DERM master plan basins.
Each DERM stormwater master plan utilized topographic LiDAR data and the available
stormwater management infrastructure data from the atlas sheets to develop sub -basin
delineations for each basin. Stormwater infrastructure data was used to refine sub -
basin delineations in areas where the topographic elevations did not provide enough
relief to accurately delineate sub -basin.
Although the City sub -basins were used to assist in the delineation, there is a clear
divergence between the City and the DERM sub -basins. Because of this divergence, a
translation methodology was proposed for this project. Initially, attempts were made to
develop a City/DERM hybrid sub -basin map by merging the two sub -basin delineations
together in GIS. The intent was to perform a union of the two data sets and to translate
4-7
January 2011 City of Miami Phase I - Stormwater Management Master Plan
the results from the DERM model sub -basins to the City sub -basins. Each City sub -
basin would be allocated to a corresponding DERM sub -basin. This methodology did
not provide a clear translation of result data because all of the sub -basin boundaries in
both data sets did not agree in location and/or direction. In a number of cases, the
union created a sub -basin map with a large number of smaller segmented sub -basins
resulting in 4 to 5 times the number of sub -basins in the original delineations. Table 4-1
shows a listing of the sub -basin count within the areas occupied by both City and DERM
sub -basins. This table also shows the average area within the sub -basin delineations
for each primary basin.
Table 4-1 — City of Miami to DERM Sub -basin Union Results
Basin
Common Basin
Area (ac)
DERM Sub -basin
Total
City of Miami
Sub -basin Total
Result of DERM to
City sub -basin Union
C-3/C-5
1,955
38
25
167
C-4
1,914
19
29
96
C-6
6,470
44
71
314
C-7
1,687
9
18
59
Total
12,026
110
143
636
Average Area per basin (acres)
109
84
_ 19*
* The small average area shown for the DERM to City sub -basin union is a result of large number of
segmented basins
Figure 4-1 shows a sample clip of the C-6 basin where the sub -basin boundaries for
both the City of Miami and the C-6 basin coexist. The image shows the DERM sub -
basin's overall disagreement with the City of Miami sub -basins. Although the limits of
certain sub -basins follow a similar direction and location, performing a union resulted in
a confusing translation that was difficult to utilize in cooperation with result data and
flood plain mapping.
Legend
Q City of Miami Subbasins
O C-6 S, bbasins
Figure 4-1 — Basins and Watersheds within the City of Miami
Additionally, revising the DERM model sub -basin delineations would require a full
reconfiguration of the models developed by DERM. In this scenario, basin data would
4-8
January 2011 City of Miami Phase I - Stormwater Management Master Plan
need to be redefined and interbasin connectivity would need to be revised. Large
numbers of additional adjustments would also be required due to the number of
parameters that are dependent on the sub -basin delineations. Revising these models
to more closely follow the City of Miami sub -basin delineation would essentially require
rebuilding and recalibrating all of the DERM basin models and would actually require
more effort than creating a new model from "scratch."
Furthermore, in order to reduce the costs associated with developing an XP-SWMM
model from "scratch," it was decided at the onset of this project, that the most
cost-effective approach would be to utilize the established DERM models for the Phase
I SWMMP models as a basis for all modeling activities corresponding to this SWMMP
Phase I update. These models were calibrated and verified and were accepted by NFIP
as representative of the hydraulic and hydrologic conditions present in Miami -Dade
County. However, it should be noted that there are some limitations with these models.
Some of the limitations include:
• Models do not represent secondary drainage conveyance systems. For drainage
systems extending through two sub -basins, only the connecting pipe(s) were
simulated in the model.
• Models primarily focused on un-incorporated areas of the County at the time the
models were developed.
• Exfiltration systems were not simulated explicitly in the models. As explained in
Section 2, exfiltration systems were simulated as a extraction of runoff using the
Green -Amp method.
• The models do not include some key stormwater improvement projects
implemented by the City but not included in the stormwater atlas sheets.
In conclusion, because the DERM sub -basins represent a delineation based on the City
of Miami atlas sheet basin delineation, the best available topographic data, and the
number of sub -basins provides only a modest increase in sub -basin areas, it was
determined that presenting result data using the DERM sub -basin delineations will
provide the most cost effective and best possible way of interpreting and utilizing the
model result data. The resulting City of Miami sub -basin delineation and the original
sub -basin delineations presented in the DERM stormwater master plans are presented
in Attachment I. These maps will be referenced from this point forward and the DERM
sub -basin delineation will be the one used in all modeling activities. Table 4-2 shows
the associated sub -basin total area, sub -basin area within the City, and percentage of
sub -basin within the City.
Table 4-2 — City of Miami to DERM Sub -basin Union Results
Sub -basin
Total Sub-
basin Area
(acres)
Area
Inside
City
(acres)
Area
Outside
City (acres)
Percentage
Inside City
95-S-1
29.5
14.8
14.7
50%
95-S-1
14.7
14.7
0.0
100%
95-S-2
19.2
19.2
0.0
100%
B4-54S
46.6
38.8
7.8
83%
4
4-9
January 2011
City of Miami Phase I - Stormwater Management Master Plan
Sub -basin
Total Sub-
basin Area
(acres)
Area
Inside
City
(acres)
Area
Outside
City (acres)
Percentage
Inside City
B4-LeJeu-W
47.0
38.9
8.2
83%
C3-N1-2
232.7
217.8
14.9
94%
C3-N2-1
254.7
164.9
89.8
65%
C3-N4-1
98.8
27.2
71.6
28%
C3-N4-2
211.3
59.6
151.7
28%
C3-N-US1-N
32.4
5.9
26.5
18%
C4-C-23
76.9
27.1
49.9
35%
C4-C-26
30.1
30.1
0.0
100%
C4-S-13
93.1
90.4
2.6
97%
C4-S-14
14.7
14.7
0.0
100%
C4-S-15
50.3
50.3
0.0
100%
C4-S-17
209.1
209.1
0.0
100%
C4-S-18
358.6
355.1
3.4
99%
C4-S-19
116.9
116.4
0.4
100%
C4-S-22
229.3
229.3
0.0
100%
C4-S-23
135.6
135.6
0.0
100%
C4-S-24
60.0
60.0
0.0
100%
C4-S-26
44.9
43.0
1.9
96%
C5-836-A
18.2
18.2
0.0
100%
C5-836-B
14.0
14.0
0.0
100%
C5-836-C
9.3
9.3
0.0
100%
C5-836-D
44.4
44.4
0.0
100%
C5-N2-1
87.7
87.7
0.0
100%
C5-N3-1
68.6
68.6
0.0
100%
C5-S1-1
49.0
49.0
0.0
100%
C5-S1-2
90.0
90.0
0.0
100%
C5-S-37-A
5.7
5.7
0.0
100%
C5-S-37-B
1.5
0.7
0.8
46%
C5-S-42-A
6.9
6.9
0.0
100%
C5-S-42-B
6.0
6.0
0.0
100%
C5-S5-1
36.5
36.5
0.0
100%
C5-S5-2
54.4
54.4
0.0
100%
C 5-S 5-3
172.5
172.5
0.0
100%
C5-S5-4
17.0
13.4
3.6
79%
C5-S6-1
47.4
47.4
0.0
100%
C5-S6-3
98.8
98.8
0.0
100%
C 5-56-4
148.3
148.3
0.0
100%
C5-S6-5
115.6
95.5
20.2
83%
C5••S7-1
65.1
65.1
0.0
100%
C5-S-7-A
5.9
5.9
0.0
100%
C5-S-7-B
4.8
4.8
0.0
100%
C5-S-FLG-A
8.2
8.0
0.1
98%
C5-S-FLG-B
5.8
5.8
0.0
100%
C5-S-FLG-C
8.9
8.9
0.0
100%
C6-12
54.2
19.9
34.3
37%
C6-N-16
574.9
52.2
522.8
9%
C6-N-17
466.8
466.8
0.0
100%
C6-N-18
142.2
142.2
0.0
100%
C6-N-19
180.9
180.9
0.0
100%
C6-N-20
144.5
144.5
0.0
100%
C6-S-12
221.2
202.3
18.9
91%
4-10
January 2011
City of Miami Phase I - Stormwater Management Master Plan
Sub -basin
Total Sub-
basin Area
(acres)
Area
Inside
City
(acres)
Area
Outside
City (acres)
Percentage
Inside City
C6-S-13
169.8
169.8
0.0
100%
C6-S-14
33.4
33.4
0.0
100%
C6-S-15
53.3
53.3
0.0
100%
C6-S-16
137.6
137.6
0.0
100%
C6-S-17
174.7
174.7
0.0
100%
C6-S-18
183.6
183.6
0.0
100%
C6-S-19
229.1
229.1
0.0
100%
C7-S-17
416.8
416.8
0.0
100%
CC4-S-20
33.3
33.3
0.0
100%
0C4-S-21
284.2
284.2
0.0
100%
CC4-S-22
195.5
195.5
0.0
100%
CC4-S-23
145.9
145.9
0.0
100%
CC4-S-25
32.9
32.9
0.0
100%
CC6-N-11
624.7
624.6
0.2
100%
CC6-N-12
748.8
719.3
29.6
96%
CC6-N-13
321.7
321.7
0.0
100%
CC6-N-14
398.0
398.0
0.0
100%
CC6-N-15
127.0
127.0
0.0
100%
CC6-N-16
265.0
265.0
0.0
100%
CC6-N-17
16.9
16.9
0.0
100%
CC6-N-18
29.7
29.7
0.0
100%
CC6-N-19
60.5
60.5
0.0
100%
CC6-N-20
132.6
132.6
0.0
100%
CC6-S-1
170.4
166.2
4.2
98%
CC6-S-2
150.1
150.1
0.0
100%
CC6-S-3
61.3
61.3
0.0
100%
CC6-S-4
15.3
15.3
0.0
100%
CC6-S-5
60.5
60.5
0.0
100%
CC6-S-6
139.7
139.7
0.0
100%
CC6-S-7
200.4
200.4
0.0
100%
CC6-S-8
315.2
315.2
0.0
100%
CC7-S-21
412.5
338.9
73.7
82%
CC7-S-22
34.9
29.3
5.6
84%
CC7-S-23
58.4
58.4
0.0
100%
CC7-S-24
357.2
357.2
0.0
100%
CC7-S-25
278.8
278.8
0.0
100%
CC7-S-26
724.2
148.7
575.5
21%
DA1-37-A
2.7
2.7
0.0
100%
DA1-37-B
9.0
8.0
1.0
89%
DA1-37-C
9.8
6.0
3.8
61%
DA1-37-D
3.8
1.6
2.2
42%
DA1-8-A
5.8
5.8
0.0
100%
DA 1-N E
129.4
129.4
0.0
100%
DA 1-S E-1
66.3
66.3
0.0
100%
DA1-SE-2
93.8
93.8
0.0
100%
N6-C6-E-1
175.0
175.0
0.0
100%
N6-C6-E-2
249.5
249.5
0.0
100%
N7-C6-W-1
28.0
28.0
0.0
100%
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January 2011 City of Miami Phase I - Stormwater Management Master Plan
4.4 C-3 Basin Model
The C-3 basin encompasses approximately 17 square miles and is generally bordered
on the west by state road (SR) 826, on the north by SW 8th Street, and on the east by
Biscayne Bay - see Attachment I. The C-3 basin lies south of the C-4 basin and east
of the C-2 basin. The primary basin canal is the C-3 Canal (Coral Gables Canal), which
begins at the northeast corner of the basin at the intersection of SR 826 and SW 8th
Street. Flow in this canal is generally to the southeast and is discharged to Biscayne
Bay in the northeast corner of Old Cutler Road, SW 42nd Avenue (LeJeune Road) and
SW 72nd Street (Sunset Drive).
Flows from the C-3 canal are controlled by the G-93 structure (Coral Gables Control
Structure). This structure is a reinforced concrete, gated spillway located on the C-3
Canal at Red Road (SW -57th Avenue), between N. Waterway Dr. (SW 34th Street) and
S. Waterway Dr. (SW 35th Street), in Miami -Dade County. The discharge from this
structure is controlled by two manually controlled vertical lift gates. The intent of this
structure is to provide salinity control to maintain an upstream surface water elevation of
2.8 feet (ft) relative to the National Geodetic Vertical Datum of 1929 (NGVD29). The
SFWMD operation rules state that the gates are opened when the upstream water
elevation reaches 4.0 ft-NGVD29 and are manually closed when the upstream elevation
reaches 3.0 ft-NGVD29. At the north end of the C-3 basin there is an open connection
with the C-4 basin at SR 826 and SW 8th Street. Flows at this point are not controlled
and can flow from the C-4 basin to the C-3 basin or conversely depending of the stage
and flow conditions within these basins.
DERM developed the C-3 basin hydrologic/hydraulic model using XP-SWMM model
Version 9.08. The model was developed with 102 sub -basins, 256 junctions, and 359
conduits and utilized a Hot -Start file to bring the model to a more realistic initial and
antecedent moisture condition prior to running a design storm event. DERM compared
the existing and future land uses and found little to no change in land use areas due to
the highly urbanized nature of this basin. Therefore, DERM only developed an existing
conditions land use model. For this specific basin, DERM established DCIA values for
the sub -catchments used to simulate exfiltration and infiltration devices using the Horton
method, instead of a zero value as established in the defined methodology. This
approach yielded better calibration results.
4.4.1 C-3 Basin Summary of Calibration/Verification
For the C-3 basin, DERM used the Hurricane Irene Event and the "No -Name Storm"
Event as calibration events. Both of these storms exceeded 10 inches of rainfall in the
basin over a 3-day period, depending upon the location in the basin. DERM attempted
to verify the model by running the calibrated model for the storm events (5-, 10-, 25-,
50-, and 100-year). The resulting peak flows at the structures were then compared to
(Log -Pearson Type III) statistical analysis of historical storm events measured at the G-
93 structure. However, the flow meter at the G-93 structure was relatively new at the
time and had only about 10 years of available data. Therefore, verification was not
possible for the C-3 basin.
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January 2011
City of Miami Phase l - Stormwater Management Master Plan
Once the calibration models were executed, stage and flows were compared at the
G-93 structure. For Hurricane Irene Event and the "No -Name Storm" events, both the
upstream and downstream stages matched very closely. For Hurricane Irene, there
appeared to be about a 5-hour shift/delay in the model peak. The "No -Name Storm"
peak time matched well. For Hurricane Irene the flows matched well for approximately
one day, then the model flow drops off more quickly than the measured flow. For the
"No -Name Storm," the peak flows matched for approximately half a day, and the stages
generally maintained good correlation. The model flow likely drops off more quickly
because it did not consider groundwater contribution/movement west of the basins.
DERM concluded that it is likely that the entire upstream groundwater levels for all of
Miami -Dade County are increased but cannot be used as a calibration parameter.
DERM believed that in order to resolve this issue, all adjacent models would have to be
executed as a single model, which is not within the scope of this SWMMP.
4.4.2 C-3 Basin Production Run Model Assumptions
Prior to performing production run model simulations, the boundary conditions were
revised for each of the outfalls. The G-93 structure gates are normally opened
according to the SFWMD rules (G-93 upstream water elevation of 3.0 ft-NGVD29).
However, for the design storm event modeling, it was assumed that the gates were
open during the entire storm events, which is normally done during flood event
conditions. For calibration, the stages downstream of the G-93 structure were set to
measured data. For the design storm event simulations, a tidal sinusoidal distribution
was used with a minimum elevation of 0.0 ft-NGVD29 and a maximum of 2.5 ft-
NGVD29. The other boundary node for the C-3 basin is the open connection with the
C-4 canal. The C-4 basin master plan was not completed at the time the C-3 basin
model development was being performed, and time -stage or time -flow relationships
were not available. Therefore, the junction representing this location in XP-SWMM was
assumed to be closed.
Several of the canal cross sections were revised to reflect the dredging activities
completed by Miami -Dade County after the calibration events. In most cases, the cross
sections were deepened several feet along the length of the cross section. The canal
dredging as -build plans were used to update the cross sections in XP-SWMM to
represent the most current canal conditions.
To decrease the continuity errors, the calibrated links with unstable low flows were
turned off. This occurred in many of the runoff links (links connecting the runoff node
generating the hydrograph to pipe manholes in the system) and roadway street links.
With this methodology, the model continuity error was reduced to less than 1% for the
production run models. The initial condition stage elevation was set for each junction,
based on the documented Miami -Dade County average October elevation.
4.5 C-4 Basin Model
The C-4 basin encompasses approximately 80 square miles and is located in
northeastern Miami -Dade County. The basin is drained primarily by the C-4 Canal, also
known as the Tamiami Canal - see Attachment I. The C-4 Canal begins in the west at
Lea]
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January 2011 City of Miami Phase I - Stormwater Management Master Plan
the L-30/L-31N Canal, and is connected to three other primary canals: the C-2, which
makes an open connection at SW 117th Avenue; the C-3 (Coral Gables Canal), which
makes an open connection just east of the Palmetto Expressway; the C-5 (Comfort
Canal), which branches from the C-4 at Blue Lagoon north of Coral Gables via gated
culvert S-25A. Normal flow is west to east with discharge to tidewaters via Structure S-
25B after connecting to the C-6 Canal (Miami Canal). There are also several secondary
canals within the C-4 basin: the Northwest Wellfield Recharge Canal, the Northline
Canal, the NW 41st Street Ditch, the Snapper Creek Canal, the NW 97th Avenue Canal,
the Westbrook Canal, the FEC Canal and the Northwest Canal. There are also six (6)
major control structures with significant impacts on the C-4 basin: S-25A, S-25B, G-119,
S-336 and Control Structure #3, and S-380. These control structures are operated by
the SFWMD except for Control Structure # 3, which is operated by Miami -Dade County.
They can be further described as follows:
• Structure S-25A: This is a manually controlled gated culvert located on the C-5
Canal (Comfort Canal) at NW 45th Avenue in the City of Miami. The structure
allows drainage from the C-4 Canal into the C-5 Canal for salinity control.
• Structure S-25B: This is a reinforced concrete, gated spillway, with discharge
controlled by two cable -operated, automatically controlled vertical lift gates. The
structure is located in the City of Miami immediately downstream of the Le Jeune
Road crossing of the C-4 Canal. This structure maintains optimum water control
stages upstream in C-4; it passes the design flood (the Standard Project Flood)
without exceeding upstream flood design stage, and restricts downstream flood
stages and discharge velocities to non -damaging levels; and it prevents saline
intrusion during periods of high flood tides.
• Control Structure # 3: This structure consists of two manually controlled gated
culverts located on the Northline Canal just east of the Florida Turnpike and the
Snapper Creek Canal. Control Structure # 3 is closed except when dry conditions
necessitate opening to provide recharge to the east C-4 basin.
• Structure G-119: This structure consists of two manually controlled gated
culverts located '/4 mile east of the Krome Avenue crossing of the C-4 Canal.
This structure permits supplemental deliveries from Water Conservation Area 3
to supply water needs in eastern Dade County via the L-30 or L-29 canals. It also
can be used to discharge limited quantities of excess water from Conservation
Area 3A or from the L-31N, L-29 and L-30 drainage basins east and south of
Conservation Area 3B when capacity is available in the C-4 Canal.
• Structure S-336: This structure consists of three manually controlled gated
culverts located immediately east of the L-30 and L-31 N Canals in the C-4 Canal.
This structure permits supplemental deliveries from Conservation Area 3 to
supply water needs in eastern Dade County via the L-30 or L-29 canals. It also
can be used to discharge excess water from Conservation Area 3A when
capacity is available in the C-4 Canal.
• Structure S-380: This structure consists of five culverts with remotely operated
slide gates located in the C-4 Canal at the intersection of the Dade-Broward
Levee and borrow canal with the C-4 Canal (approximately 2 miles east of Krome
Avenue). The purpose of S-380 is to maintain stages to create and preserve
4-14
January 2011 City of Miami Phase I - Stormwater Management Master Plan
wetlands as well as enhance water supply by providing aquifer recharge. S-380
will be operated to enhance approximately 4,000 acres of wetlands in the
southern end of the adjacent Pennsuco Wetlands and enhance habitat for plants
and animals by increasing surface and subsurface storage of water. This will be
accomplished by reducing seepage and drainage out of Water Conservation
Area 3B. In addition, the structure will permit supplemental deliveries from Water
Conservation' Area 3 to supply water needs in eastern Dade County via the L-30
or L-29 canals. (Note: Construction of S-380 was completed in July 2003 and
was only included in Future Conditions model simulations.)
There are three other stormwater management facilities in the C-4 basin: Control
Structures #1, #2, and #4 are operated by Miami -Dade County. Control Structure #1
connecting the Northwest Wellfield Recharge Canal to the L-30 Canal is usually closed.
Control Structure #2 connecting Snapper Creek Canal and Dressels Canal is usually
closed. Control Structure #4 located in the Snapper Creek Canal at NW 12th Street is
usually open.
DERM developed the C-4 basin hydrologic/hydraulic model using XP-SWMM model
Version 8.87. The model was developed with 245 sub -basins, 449 junctions, and 687
conduits. DERM followed the planning procedures defined above in developing the
hydrologic and hydraulic components of the model, with little to no deviations. Using
this approach, DERM developed both an existing and future conditions model for the
basin. For This basin DERM used 2000 land used data instead of the 2005 land use
implemented in other basins.
4.5.1 C-4 Basin Summary of Calibration/Verification
For the C-4 basin, DERM used three calibration events:
• Hurricane Irene (October 1999) - From October 13-17, 1999, the Miami Airport
(miami_r) rainfall station recorded 13.7 inches of rain, the Tamiami station
(s336_r) recorded 14.4 inches, and the Pennsuco station (s30_r) recorded 7.3
inches. In order to mimic the observed stage and flow data, the S-25B gate
opening information obtained from SFWMD was entered in the model using the
"Vary with Time" option for orifices. According to the SFWMD, Structure G-119
remained closed during this event and the XP-SWMM model was modified to
replicate this structure's operation.
• "No Name Storm" (October 2000) - From October 1-5, 2000, the Miami Airport
(miami_r) rainfall station recorded 14.2 inches of rain, the Tamiami station
(s336_r) recorded 11.4 inches, and the Pennsuco station (s30_r) recorded 7.2
inches. In order to mimic the observed stage and flow data, the S-25B gate
opening information obtained from the SFWMD was entered in the model using
the "Vary with Time" option for orifices. According to the SFWMD, Structure
G-119 remained closed during this event and the XP-SWMM model was modified
to replicate this structure operation.
• June 1997 Storm Event - From June 8-12, 1997, the Miami Airport (miami_r)
rainfall station recorded 9.8 inches of rain, the Tamiami station (s336_r) recorded
8.8 inches, and the Pennsuco station (s30_r) recorded 4.7 inches. In order to
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January 2011 City of Miami Phase I - Stormwater Management Master Plan
mimic the observed stage and flow data, the S-25B gate opening information
obtained from SFWMD was entered in the model using the "Vary with Time"
option for orifices. According to the SFWMD, Structure G-119 remained closed
during this event and the XP-SWMM model was modified to replicate this
structure operation.
Once the calibration models were executed, stages, flows and volumes were compared
at outfall structures which had recorded data that correlated to the time duration of the
calibration events. The following is a summary of the calibration results for each of the
calibration storm events:
• Hurricane Irene (October 1999) - The difference between the total observed
and total simulated flow volume at the S-25B structure was 8.8%. The variations
in peak flow and peak stage between observed and simulated values this
structure were 15.4% and 1.5%, respectively. The differences in peak stages at
C4 Coral, G-119 and S-336 structures were 3.3%, 1.5% and 2.3%, respectively
and the receding stormwater stage is accurately modeled. The computed peak
stages and recession limbs showed good agreement with observed data at all
structures.
• "No Name Storm" (October 2000) - The difference between the total observed
and total simulated flow volume at the S-25B structure was 13.5%. The variations
in peak flow and peak stage between observed and simulated values at this
structure were 25.8% and 3.3%, respectively. The differences in peak stages at
C4.Coral, G-119 and S-336 structures were 1.8%, 7.5% and 11.9%, respectively.
• June 1997 Storm Event The difference between the total observed and total
simulated flow volume at the S-25B structure was 3.7%, The variations in peak
flow and peak stage between observed and simulated values this structure were
3.4% and 0.5%, respectively. The differences in peak stages at C4.Coral, G-119
and S-336 structures were 6.3%, 11.1% and 20.7%, respectively.
DERM verified the models by running the calibrated model for the storm events (5-, 10-,
25-, 50-, and 100-year) and comparing results to Log -Normal statistical distributions the
S-25B structure. Although both the Log -Normal and Log -Pearson III distributions were
examined, it was found that a Log -Normal distribution was a better fit for the observed
data. The simulated flows fall slightly above the 95% confidence limits for each of the
storms. One reason that the modeled results have higher values than the Log -Normal fit
of the observed peak flow values is that differences exist in the operation of the flood
gates at the outfall structure. For the design event simulations, the S-25B structure
gates were modeled completely open.
For the purposes of the C-4 stormwater master planning, DERM concluded that the
event models are considered reasonably calibrated within the limits of the available data
and technology.
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January 2011 City of Miami Phase I - Stormwater Management Master Plan
4.5.2 C-4 Basin Production Run Model Assumptions
Prior to performing production run model simulations, the existing land use conditions
model boundary conditions were revised for each of the model outfalls and
interconnection with other basins, as follows:
® C-4 Basin to Water Conservation Area 3 — The C-4 basin is hydraulically
connected to Water Conservation Area 3 at two locations.
o The Northwest Wellfield Recharge Canal connects to the L-30 via Control
Structure # 1.
o The C-4 Canal connects to the L-30 and L-29 Canals approximately 1 mile
west of Krome Avenue via gated culvert S-336.
For Control Structure # 1 DERM assumed that this structure was closed at all
times. Therefore, a no -flow boundary condition was assumed at this location for
design event. From the information obtained from the SFWMD, it was also
assumed that the S-336 is closed for all design event simulations.
o C-4 Basin to C-2 Basin Boundary Conditions — The C-4 basin is hydraulically
connected to the C-2 basin at three locations:
o The C-4 Canal connects to the south branch of the Mud Creek Canal just
east of S.W. 132nd Avenue.
o The C-4 Canal connects to the C-2 Canal just northeast of the intersection
of the Florida Turnpike and S.W. 8th Street. (Snapper Creek/C-2/C-4
confluence).
o The Westbrook Canal connects to the C-2 Canal at the southwest corner
of the Florida International University Campus at the intersection of the
Florida Turnpike and S.W. 24th Street.
No control structures or measured time -series data exist at these locations.
However, simulated time -series stage data was available at the C-4/C-2
confluence from prior modeling activities by PBS&J and was entered as a
boundary condition for the design event calibration simulations. This information
was based on the C-4 Flood Mitigation Project Basin Study performed by PBS&J
that included development of a C-4/C-3 XP-SWMM model for Department of
Community Affairs and SFWMD.
G C-4 Basin to C-3 Basin Boundary Conditions — The C-4 basin is hydraulically
connected to the C-3 basin just east of the Palmetto Expressway. No control
structure or measured time -series data exists at this location. However,
simulated time -series stage data was available at the C-4/C-3 confluence from
prior modeling activities by PBS&J and was entered as a boundary condition for
the design event calibration simulations. This information was based on the C-4
Flood Mitigation Project Basin Study performed by PBS&J that included
development of a C-4/C-3 XP-SWMM model for Department of Community
Affairs and SFWMD.
• C-4 Basin to C-5 Basin Boundary Conditions — The C-4 basin is hydraulically
connected to the C-5 basin at the Blue Lagoon north of Coral Gables via gated
culvert S-25A structure. The S-25A structure is operated solely for salinity control
and is opened when the headwater elevation of S-25 drops below 1.5 feet. S-25
is located approximately 2 miles east of S-25A in the C-5 Canal. Based on
January 2011 City of Miami Phase I - Stormwater Management Master Plan
recorded data and typical SFWMD operation of the S-25A structure, this
structure was assumed to be closed for all design event simulations.
• C-4 Basin to C-6 Basin Boundary Conditions — The C-4 basin is hydraulically
connected to the C-6 basin at four locations
o The Snapper Creek Canal at NW 122nd Street
o The intersection of the Snapper Creek Canal and Dressels Canal at NW
58th Street
o The FEC Canal northwest of the Miami International Airport
o The S-25B Structure.
For the design event simulations, no -flow boundary conditions were assumed
for all C-4 / C-6 connections except for the S-25B structure. For the design
event and design continuous simulations, the one-year stillwater elevation for
the area was used as the maximum tidal elevation. DERM implemented a
sinusoidal tide with an average amplitude of 3 feet and a 12.5-hour period to
better represent the normal operation of the outfall structure in the simulations.
The one-year stillwater was estimated using 17 years of recorded data and
Federal Emergency Management Agency (FEMA) maps for the 100 year and
500 year maximum water surface elevations.
Under FEMA guidelines, tidal elevation return periods and rainfall intensity
return periods are considered independent. However, studies have shown that
high tides and high rainfall volumes may occur simultaneously in Florida due to
hurricanes. Using the one-year stillwater elevation as a fixed backwater
elevation is a standard practice that has been used in many stormwater models
throughout Florida. By using a one-year stillwater elevation of 3.5 feet NGVD as
the maximum tidal elevation and allowing the tide to fall in a sinusoidal fashion,
the model can be considered both practically conservative and simulating real
conditions. The maximum tide was Lagged to match the peak flow at the outfall
to keep the model conservative.
DERM further revised the existing land use conditions model to include 2025 future land
uses. The model was also revised to include the following significant flood protection
and water resources projects implemented after 2000.
• A pump station at the S-25B structure with a capacity of 600 cfs (200 cfs per
pump), for forward pumping prior to a major forecasted storm event.
• Construction of an 836-acre emergency detention basin with a total storage
volume of approximately 3,344 acre-feet. The maximum design water depth is 4
feet with a bottom elevation of 6 feet NGVD.
• A pump station, G-420, with a rated capacity of 1,500 cfs, designed to pump
flows into the emergency detention basin.
• Construction of a supply canal from the C-4 Canal to the reservoir. The supply
canal is located along the east side of the detention basin and connects the C-4
Canal to the G-420 intake. The supply canal has a length of approximately 3,800
feet and also has the capacity to handle the return flows from the emergency
detention basin to the C-4 Canal.
January 2011 City of Miami Phase I - Stormwater Management Master Plan
• Construction of an emergency spillway from the emergency flood impoundment.
o Construction of control structure S-380. The structure is located on the C-4 Canal
upstream of the supply canal. It is simulated to be closed during back pumping
operation per the operation criteria provided by the SFWMD.
o Canal improvements consisting of deepening and widening the C-4 Canal from
approximately one mile east of the S-380 structure to '/4 mile west of 127th
Avenue and deepening the C-4 Canal from ' mile west of 127th Avenue to the
Florida Turnpike:
-• Construction of a berm along the C-4 canal left bank to an elevation 8.0 feet-
NGVD29 from the supply canal to 97th Avenue.
o Canal improvements at strategic points downstream of 109th Avenue including
the canal reaches between 109th Avenue and 97th Avenue, the Railroad Bridge,
and the section of canal from 14th Street to S-25B.
o Construction of a gated culvert in the Northwest Wellfield Recharge Canal
(NWRC) at NW 137m Avenue (completely closed for future conditions production
runs).
o Construction of a gated culvert in the NW 25th Street Canal (Northline Canal) just
west of the Florida Turnpike (completely closed for future conditions production
runs).
o Proposed Belen pump stations.
• Proposed Sweetwater pump stations.
o Proposed West Miami and Miami simulated inflow from proposed pump stations.
For the C-4 basin, DERM used an initial water depth at all nodes of 3.5 ft-NGVD29.
4.6 C-5 Basin Model
The C-5 basin encompasses approximately 3 square miles and is generally located
along the northeast border of the C-3 basin at SW 8th Street - see Attachment 1. The
drainage system in SW 8th Street can receive flow from both the C-3 and C-5 basins.
The C-5 basin is also bordered on the west by the C-4 basin, on the north by the C-6
basin and on the southeast end by the DA-1 South Biscayne Bay basin. The primary
basin canal is the C-5 Canal (Comfort Canal), which begins on the east side of
Structure S-25A, just south of where SR 836 intersects NW 45th Avenue and terminates
at the west end of Structure S-25. Flow in the canal is generally to the east, meandering
south and north of SR 836 through several culverts, past Structure S-25. Flow from the
C-5 canal is discharged to the Miami River (C-6 basin) south of North River Drive near
NW 19th Avenue.
Flows from the C-5 canal are controlled by two control structures: S-25 and S-25A
structures and are described as follows:
o Structure S-25: This structure maintains an optimum water level of 2.0 ft-
NGVD29 in the C-5 Canal (Comfort Canal) and release flows to prevent flooding.
This structure is a single -barreled, corrugated metal pipe culvert, located on the
Comfort Canal west of NW 27th Avenue in the City of Miami. Discharge is
controlled by an automatically -operated slide gate on the west end of the culvert.
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January 2011 City of Miami Phase I - Stormwater Management Master Plan
The gate is automatically opened at an upstream elevation of 2.2 ft-NGVD29 to
release water and closed when the canal water levels drop to 1.8 ft-NGVD29.
Structure S-25A: This structure is a single -barreled, corrugated metal pipe
culvert, located on the C-5 Canal (Comfort Canal) at NW 45th Avenue just south
of SR 836, in the City of Miami. Discharge is controlled by a manually operated
sluice gate mounted on the west end of the culvert. The sole purpose of this gate
is salinity control. When the water level in the C-5 Canal (Comfort Canal) recedes
below 1.5 ft-NGVD it is manually opened to fill the canal. However, this structure
is usually maintained closed by the SFWMD.
DERM developed the C-5 basin hydrologic/hydraulic model using XP-SWMM model
Version 9.08. The model was developed with 33 sub -basins, 113 junctions, and 175
conduits and utilized a Hot -Start file to bring the model to a more realistic initial and
antecedent moisture condition prior to running a design storm event. DERM compared
the existing and future land uses and found little to no difference in land use areas due
to the highly urbanized nature of this basin. Therefore, DERM only developed an
existing land use condition model. As for the C-3 basin, DERM established DCIA
values for the sub -catchments used to simulate exfiltration and infiltration devices using
the Horton method, instead of a zero values as established in the defined methodology,
because this approach yielded better calibration results.
4.6.1 C-5 Basin Summary of Calibration/Verification
For the C-5 basin, DERM used the Hurricane Irene Event and the "No -Name Storm" as
calibration events. Both of these storms exceeded 10 inches of rainfall in the basin over
a 3-day period, depending upon the location in the basin. DERM attempted to verify the
model by running the calibrated model for the storm events (5-, 10-, 25-, 50-, and 100-
year). The resulting peak flows at the structures were then compared to (Log -Pearson
Type III) statistical analysis of historical storm events measured at the S-25 structure.
The flow meter at the S-25 structure, however, is relatively new and has less than 10
years of available data. Therefore, verification was not possible for the C-5 basin.
Once the calibration models were executed, stage and flows were compared at the
S-25 structure. For the "No -Name Storm," the rising flows matched well, but the model
peak was approximately 25% higher and sustained longer than measured flows. For the
Hurricane Irene event, the measured flows at the C-5 appeared unreliable for calibration
purposes. In review of the measured stages, the stage elevation at the downstream
gate was higher than the upstream gate. From the recorded structure operations, the
gates were open. Thus, the water was flowing from the C-6 Canal upstream into the C-5
Canal. The model also shows this backflow up until the major rainfall, and then a
positive flow is observed from the C-5 basin. According to the S-25 structure gate
operation records, it appears that the gates were opened and closed several times to
better control the flows. These gates are manually operated, and because of the manual
gate operation and the backflow of water, this storm event was deemed by DERM not to
be a valid candidate for calibration.
For the "No -Name Storm," the reliability of the flow meter at the gate was questionable
(12.8 percent correction factor per USGS for low events). The peak flows in the C-5
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January 2011 City of Miami Phase I - Stormwater Management Master Plan
canal are approximately 25% higher than the reported flows. The computed stages,
however, showed very good correlation with the recorded stages. The higher model flow
could be attributed to more delayed storage that was available in the C-5 basin but not
accounted for in the model setup. One theory was that the C-5 basin area is generally a
low lying area with a substantial amount of low isolated areas where stormwater would
not readily flow out. However, the model representation of the sub -basins provides low
points (overland flow cross sections) for the runoff to flow more quickly rather than be
held back. Regardless of the flow correlation, the stage correlation of the "No -Name
Storm" was very good.
For the purposes of the C-5 stormwater master planning, DERM concluded that the
event models are considered reasonably calibrated within the limits of the available data
and technology.
4.6.2 C-5 Basin Production Run Model Assumptions
Prior to performing production run model simulations, the boundary conditions were
revised for each of the outfalls. The S-25 structure gates are normally opened
according to the SFWMD rules. However, for the design storm event modeling, DERM
assumed that the gates were open during the entire storm events, which is normally
done during flood event conditions. For calibration, the stages downstream of the S-25
structure were set to measured data. For the design storm event simulations, a tidal
sinusoidal distribution was used downstream of the S-25 structure with a minimum
elevation of 0.0 ft-NGVD29 and a maximum of 2.5 ft-NGVD29. The S-25A structure
located at the west end of the basin was assumed closed for all design storm events.
As for the C-3 basin, several of the canal cross sections were revised to reflect the
dredging activities completed by Miami -Dade County after the calibration events. In
most cases, the cross sections were deepened several feet along the length of the
cross section. The canal dredging as -build plans were used to update the cross
sections in XP-SWMM to represent the most current canal conditions.
To decrease the continuity errors, the calibrated links with unstable low flows were
turned off, as was done for the C-3 basin modeling activities. This occurred in many of
the runoff links (links connecting the runoff node generating the hydrograph to pipe
manholes in the system) and roadway street links. With this methodology, the model
continuity error was reduced to Tess than 1% for the production run models. The initial
condition stage elevation was set for each junction, based on the documented Miami -
Dade County average October elevation.
4.7 C-6 Basin Model
The C-6 basin encompasses approximately 70 square miles and is located in northern
Miami -Dade County - see Attachment I. Due to its size, the C-6 basin extends over
unincorporated and incorporated areas of the County, covering several municipalities
which included Miami, Hialeah, Hialeah Gardens, Miami Springs, Medley, Virginia
Gardens, and Doral. The land uses within the basin were varied. The southeast portion
of the basin includes downtown Miami, a largely urban area. The central areas of the
January 2011 City of Miami Phase I - Stormwater Management Master Plan
basin are predominantly composed of single-family residential land uses and some
industrial/warehouse areas. The northwest portion of the basin is not associated with
any of the municipalities and mostly consists of agricultural areas and some single-
family residential land uses.
This basin is bound on the north by basins C-7, C-8, and C-9 West; on the south by
basins C-4, C-5, and DA-1 South Biscayne basin; on the west by basin C-4 and Water
Conservation Area (WCA) 3A; and on the east by Biscayne Bay. There are also a
number of secondary canals within the C-6 basin that are tributary to the C-6 canal
which are:
• Gratigny Canal
• Dressels Canal
• Graham Dairy Canal
• 58th Street Canal
O Wagner Creek
• Lawrence Waterway
• Melrose Canal
O Rail Road Canal
• Russian Colony Canal
• Pennsuco Canal
Flows from the C-6 basin are primarily controlled by the S-26 structure. This structure is
located in the City of Miami at the NW 36th Street crossing of the C-6 can& and is
comprised of a reinforced concrete, gated spillway, with discharge controlled by two
cable operated, vertical lift gates driven by overhead horizontal hydraulic cylinders.
Operation of the gates is automatically controlled by the SFWMD. The purpose of this
structure is to pass the design flood (the Standard Project Flood) without exceeding
upstream flood design stages, restricting downstream flood stages and discharge
velocities to non -damaging levels, and preventing saline intrusion during periods of high
flood tides. This structure is automatically operated to maintain, as close as possible,
the optimum headwater elevation of 2.5 ft-NGVD29. The gates operate to maintain the
optimum upstream water surface elevations as follows:
• When the headwater elevation rises to 2.8 ft-NGVD29, the gates open at a rate
of six inches per minute.
• When the headwater elevation rises or falls to 2.5 ft-NGVD29, the gates become
stationary.
• When the headwater elevation falls below 2.3 ft-NGVD29, the gates close at a
rate of six inches per minute.
During extreme flood events, the structure is placed on a low range operation as
follows:
• When the headwater elevation rises to 1.7 ft-NGVD29, the gates open at six
inches per minute.
January 2011 City of Miami Phase I - Stormwater Management Master Plan
e When the headwater elevation rises or falls to 1.6 ft-NGVD29, the gates become
stationary.
O When the headwater elevation falls to 1.2 ft-NGVD29, the gates close at six
inches per minute.
A special timing device at this site was installed to protect manatees during automatic
gate operation. This device causes alternate gate operation. During this operation,
when the upstream float sensor indicates that the gates should open, one gate opens a
minimum of 2.5 ft-NGVD29. If this opening results in a headwater stage below the gate
close level, as it often does, this gate will close. Whenever the headwater stage again
rises to the gate open level, the other gate will open in a similar manner. In addition to
maintaining optimum upstream fresh water control, as described above, the automatic
controls on this structure have an overriding control which closes the gates, regardless
of the upstream water level in the event of a high flood tide, whenever the differential
between the S-26 headwater and tailwater pool elevations reaches 0.3 ft-NGVD29.
A pump station was added in August 2003 to the S-26 structure to reduce headwater
stages during high tides. The main feature of this pump station is three200 cfs capacity
pumps working at 1.2 feet of head per pump.
There are also other control structures located within the C-6 basin that are operated by
the SFWMD as follows:
o Structure S-31: This structure is located where L-30 (levee) crosses the Miami
Canal (C-6 Canal). It controls discharges from Water Conservation Area (WCA) 3
to the Miami Canal. It permits release of water from WCA 3 to supply water
needed along the Miami Canal during the dry season to maintain the S-26 water
level at 2.5 ft-NGVD29. During the wet season, the structure can be used to
discharge excess water from WCA 3B when capacity is available in the Miami
Canal. In those cases, gates in this structure are opened whenever excess
storage is present in the WCA 3A and/or WCA 3B providing that the tailwater
elevation does not exceed 4.0 ft-NGVD29.
o Structure S-32: This structure connects the borrow canal of L-33 (levee) with the
Miami Canal. This structure controls water stored between L-33 and U.S.
Highway 27. During flood conditions, gates of this structure should be closed
when tailwater reaches 4.0 ft-NGVD29. Otherwise, the gates can be opened
when the headwater is higher than 6.0 ft-NGVD29. During dry conditions,
releases are made based on the downstream requirements.
O Structure G-72: This structure connects the C-6 Canal with the head (west) end
of the C-7 Canal. The structure is closed during floods since it is not designed to
pass flood flows. This structure is normally closed. It is opened only when
supplemental water is needed in the C-7 basin to maintain optimum levels at
S-27.
O Structures S-25 and S-25A: These structures connect the C-5 Canal with the
portion of the C-6 Canal that is directly connected to the tide (downstream of
Structure S-26), as discussed above.
z.EL
4-23
January 2011 City of Miami Phase I - Stormwater Management Master Plan
Structure S-25B: This structure connects the Tamiami Canal (C-4 Canal) with
the portion of the C-6 Canal that is directly connected to the tide (downstream of
Structure S-26), as discussed previously.
DERM developed the C-6 basin hydrologic/hydraulic model using XP-SWMM model
Version 9.24. The model was developed with 310 sub -basins, 521 junctions, and 784
conduits. DERM followed the planning procedures defined previously in developing the
hydrologic and hydraulic components of the model, with little to no deviations. As for
the C-5 basin, DERM established DCIA values for the sub -catchments used to simulate
exfiltration and infiltration devices using the Horton method, instead of a zero values as
established in the defined methodology, because this approach yielded better
calibration results. DERM used the same Width parameter for all catchments
regardless of the difference in catchment area.
4.7.1 C-6 Basin Summary of Calibration/Verification
DERM selected the Hurricane Irene (October 1999) storm as the calibration event
because of its magnitude and recent occurrence and the "No -Name Storm" (October
2000) for verification. Both of these events exceeded 10 inches of rainfall over a 3-day
period depending upon the location. The Miami Airport (MIA), Miami Beach, S-26,
Sylva, Hialeah, Miami Field Station, and Pennsuco gauges were the closest gauges that
collected reliable rainfall data for the C-6 basin; only hourly data was available
Once the calibration models were executed, stage, flows and volumes were compared
at outfall structures which had recorded data that correlated to the time duration of the
calibration events. For each event, both the peaks and the stages matched closely. The
"No -Name Storm" peak time also matched the model well. For Hurricane Irene the flows
matched the model well, and for the "No -Name Storm," the peak flows also matched
fairly well and the stages generally sustained good correlation. The S-26 Gate
Operation Records from the SFWMD show that the gates were opened during
Hurricane Irene. The model also shows this backflow until the major rainfall, then a
positive flow out. According to the Gate Operation Records, it appears that the gates
were opened and closed several times to better control the flows. These gates are
manually operated. XP-SWMM has an additional Real -Time Control (RTC) feature that
could better model the time operation of the gates, but it was not employed for
calibration or verification purposes.
For the purposes of the C-6 stormwater master plan, DERM concluded that the event
models were reasonably calibrated within the limits of the available data and
technology.
4.7.2 C-6 Basin Production Run Model Assumptions
Prior to performing production run model simulations, the existing and future land use
conditions model boundary conditions were revised for each of the model outfalls and
interconnections with other basins. The S-26 structure gates are normally opened
according to the SFWMD operating rules. However, for the design storm event
modeling, DERM assumed that the gates were open during the entire storm events,
January 2011 City of Miami Phase I - Stormwater Management Master Plan
which is normally done during flood event conditions. For calibration, the stages
downstream of the S-26 structure were set to measured data. For the design storm
event simulations, a tidal sinusoidal distribution was used at the model discharge point
into Biscayne Bay, with a minimum elevation of -0.4 ft-NGVD29 and a maximum of 2.7
ft-NGVD29.
The inflow hydrographs from adjacent basins that drain into the C-6 basin were used as
boundary conditions, based on the other XP-SWMM modeling activities performed by
DERM for the C-4, C-5 and C-7 basins. The Red Road Canal (C-7 inflow) was obtained
from the C-7 XP-SWMM modeland input as a stage history outfall. The C-4 and C-5
inflows were obtained from the C-4 and C-5 basin XP-SWMM models and were also
input as stage history outfalls. Seepage from WCA 3 was modeled using the special
conduit option in the model. Seepage was modeled as a function of a seepage factor
(cfs/ft/mile) applied to the length of the basin that receives seepage from WCA 3. C-6
canal levels were calculated by the model while elevations in the WCA 3 were entered
as a boundary condition from SFWMD records during Hurricane Irene and the "No -
Name storm."
As for the C-3 basin, several of the canal cross sections were revised to reflect the
dredging activities completed by Miami -Dade County after the calibration events. The
canal dredging as -build plans were used to update the cross sections in XP-SWMM to
represent the most current canal conditions. The pump station constructed in 2003 at
the S-26 structure was also incorporated in the existing and future condition land use
XP-SWMM models. This pump station was simulated based on the SFWMD operating
conditions for this pump station. For the C-6 basin DERM used an initial water depth at
all nodes of 2.0 ft-NGVD29.
4.8 C-7 Basin Model
The C-6 basin encompasses approximately 30 square miles and is located in northern
Miami -Dade County - see Attachment I. The C-7 basin is surrounded by the C-8 basin
on the north and the C-6 basin on the south and west sides. The basin drains to
Biscayne Bay in the east through the SFWMD control structure S-27. The northern
boundary of the C-7 basin is defined by NW 135th Street between NW 87th Avenue and
NW 7th Avenue. The western boundary of the C-7 basin is defined by NW 87th Avenue.
between NW 135th Street and W. 49th Street (Hialeah — NW 103rd Street in Miami).
The eastern boundary is approximately defined by NW 7th Avenue (between NW 135th
Street and NW 119th Street) and NE 2nd Avenue (between NE 119th Street and NE
71 st Street). The southern edge of the basin is irregular and reaches as far south as
NW 54th Street.
There are two major canals and five tributary canals in the C-7 basin. The major canals
are the C-7 and the Red Road Canals. The smaller canals are the Gratigny Canal, the
Palmetto Canal, the C-7 Spur Canal, the 98th Street Canal, and the 127th Street Canal.
The C-7 basin connects with the C-8 basin through culverts at NW 22nd Avenue and
NW 135th Street (the Spur Canal), Red Road Canal's intersection with the Gratigny
Expressway (State Road 924), and the northwest corner of the basin where the
Palmetto Expressway (State Road 826) merges with 1-75 (Palmetto Canal). The C-7
January 2011 City of Miami Phase I - Stormwater Management Master Plan
basin connects with the C-6 basin at 87th Avenue and the Gratigny Canal, and where
the Red Road Canal intersects with the southern boundary of the basin (approximately
81 st Street (26th Street in Hialeah).
There are three control structures that control discharges from the C-7 basin and are
described as follows:
• Structure S-27: This structure is a gated spillway located in the C-7 Canal
approximately 6,000 feet inland from Biscayne Bay, near the intersection of the
C-7 Canal and NE 81 st Street (approximately 1,000 feet west of US-1). It controls
the stage in the lower reaches of C-7 canal, and it regulates discharges to the
downstream areas. A headwater stage is maintained by S-27 adequate to
prevent saltwater intrusion into local groundwater. DERM used the "bendable
weir" option in.XP-SWMM to closelysimulate the operation of S-27 for production
simulations. This option allows the user to specify depths at which the weir is
opened and closed.
• Structure G-72: This structure is located at the intersection of the C-7 Canal with
the western edge of the basin (NW 87th Avenue and NW 103`d Street) and at one
time connected the C-7 basin to the C-6 Canal. The corrugated metal pipe
culvert is now closed with the pipe bent fully upward. It is expected that very little,
if any, flow passes from the C-6 basin to the C-7 basin at this structure.
o Structure U7-55: This structure is located on the 127th Street Canal at culvert
U7-55 (NW 127th Street just west of NW 27th Avenue). This structure consists of
a wooden gate that may be lowered manually to block flow though the 127th
Street Canal at U7-55. Since there is no data of the operation of the structure,
and the structure appears to be in a state of disrepair, the structure is simulated
as open at all times in the model.
DERM developed the C-7 basin hydrologic/hydraulic model using XP-SWMM model
Version 9.10. The model was developed with 154 sub -basins, 258 junctions, and 406
conduits. DERM developed a existing land use calibration model that did not include
improvement projects or canal dredging. For the production models, improvement
projects or canal dredging projects were included in the existing land use calibration
model. A future land use model was not developed.
DERM followed the planning procedures defined previously in developing the hydrologic
and hydraulic components of the model, with little to no deviations. DERM used the
"bendable weir" option in XP-SWMM to closely simulate the operation of S-27 for
production simulations. This option allows the user to specify depths at which the weir is
opened and closed. For the calibration, DERM used the actual gate opening data, depth
of opening versus time, at either 15-minute intervals or in break-point format for both
gates of the S-27 Structure. To simulate the openings, DERM used two "dummy" nodes
with the depth (the "dummy" node is an outfall, depth is set using the "User Stage
History" input) set at the percent opening of each gate versus time. This information is
read by two links in the model that connect to the outfall through a flap gate (i.e., only
positive flow though the structure). These two links consist of an inflatable weir in
combination with a rectangular conduit.
January 2011 City of Miami Phase I - Stormwater Management Master Plan
4.8.1 C-7 Basin Summary of Calibration/Verification
DERM used the following recorded rainfall events for calibration:
• Hurricane Irene (October 1999) - The 13-day recorded rainfall event total
precipitation was 12.3 inches (72-hour volume of 11.0 inches) at Miami
International Airport (MIA). The rainfall volume varied significantly over the C-7
basin from 16 inches to 9 inches.
• "No Name Storm" (October 2000) - The 13-day model simulation's total
precipitation was 18.2 inches (72-hour volume of 15.3 inches) at MIA.
• November 1998 Storm Event - The 13-day model recorded total precipitation
was 5.9 inches (72-hour volume of 5.9 inches) at MIA. There was insufficient
data to introduce a spatial rainfall distribution for this storm.
Once the calibration models were executed, stage, flows and volumes were compared
at the S-27 structure. The following is a summary of the calibration results for the three
calibration events:
• Hurricane Irene (October 1999) - The percentage difference between the total
observed flow and simulated flow volumes at the S-27 structure were -0.7%. The
variations in peak flow and peak stage between observed and simulated values
were -1.4% and 0.3%, respectively, and the receding stormwater was accurately
modeled. The predicted peak stages and the shape of the recession limbs
showed good agreement with the observed data. The modeled and observed
flows and stages were best matched after the bulk of the rainfall from the storm
was recorded. The flow through the outfall averaged over 1,000 cfs, five days
after the peak of the storm. This situation is due to lateral groundwater flow
through the basin from western areas, including the Everglades. The model
cannot supply this flow from surface runoff and groundwater baseflow alone.
Additional groundwater supply nodes were used to simulate the lateral flow from
neighboring areas, as was the user supplied inflow based on the combination of
prior rainfall and the storm event.
• "No Name Storm" (October 2000) - The percentage difference between total
observed flow and simulated flow volumes at the S-27 structure was 4.3%. The
variations in peak flow and peak stage between observed and simulated values
were -1.1% and -2.1% respectively, although the peak observed flow does not
occur during the peak of the storm (as measured by rainfall or stage). For this
calibration period, the observed flow would be expected to peak on the evening
of the 15th of October through the morning of the 16th, near the time of the peak
stage. One potential explanation is that the flow could not be properly measured/
calculated at this time by the SFWMD. Stages are measured directly and are
generally more accurate. For this storm, the flow through the outfall averages
over 1,250 cfs five days after the peak of the storm. The basis is again that this
situation is due to lateral groundwater flow through the basin from areas west,
including the Everglades.
• November 1998 Storm Event - The percentage difference between total
observed flow and simulated flow volumes at the S-27 was -14.1%. The
variations in peak flow and peak stage between observed and simulated values
January 2011 City of Miami Phase I - Stormwater Management Master Plan
were -7.9% and -1.7%, respectively. For this storm,_ the flow through the outfall
averaged over 750 cfs for four days after the peak of the storm, though the storm
was less than 6 inches and there was no precipitation during this time period.
The model attempted to match these values with the groundwater supply nodes
and user input hydrographs, but fell somewhat short, resulting in a total flow error
just outside DERM's desired tolerance. Attempts to match this flow resulted in
overly high flows for the other storms and the continuous calibrations. Note that
for this storm, there was no additional rainfall data available (such as aerial
distributions of total volume). It is possible that there was significantly more
rainfall in areas west of the C-7 basin then was recorded in the available (MIA)
gauge.
DERM verified the models by running the calibrated model for the storm events (5-, 10-,
25-, 50-, and 100-year) and comparing results to Log -Pearson III statistical distributions
the S-27 structure. The historical flow observations were limited to a 20-year period
(1985-2004) due to lack of peak flow data prior to 1985. The 25-year storm's peak flow
fell just outside the 95% confidence intervals. This may be attributed to the SFWMD's
rainfall volume being near the 100-year storm volume. Overall, verification runs of the
design storm events matched well with the recorded data at the S-27 structure.
For the purposes of the C-7 stormwater master planning, DERM concluded that the
event models are considered reasonably calibrated within the limits of the available data
and technology.
4.8.2 C-7 Basin Production Run Model Assumptions
Prior to performing production run model simulations, the existing land use conditions
calibration model boundary conditions were revised for each of the model's outfalls and
interconnections with other basins. The model setup of the S-27 structure in the
calibrated model was changed from the gate operation/inflatable weir condition to the
stage in S-27H/ bendable weir and rating curve. Since the gate operation during design
events were not know, the SFWMD operation guidelines for Structure S-27, which
depended upon headwater stages, were implemented using a bendable weir. Several
key improvements in the basin were also represented in the model. The culverts in the
Red Road Canal were removed or replaced and the canal was dredged in 2002. The
Gratigny and C7-Spur Canals were also dredged. Node inverts were changed as
necessary to account for the deeper natural cross sections or the renovated culverts.
The initial condition stage elevation were set for each junction, based on the
documented Miami -Dade County average October elevation.
For the boundary conditions between the C-7 and C-8 basins, DERM used the C-8
basin production model results and used these results to establish flow versus stage
rating curves at the interconnection points between these two basins. The boundary
condition indicated flow out of the C-7 basin, into the C-8 basin for all times where the
stage in the C7-Spur Canal was greater than 2.0 ft-NGVD29 and no flow for stages Tess
than this value. The boundary condition also indicated flow out of the C-7 basin, into the
C-8 basin for all times where the stage in the Red Road Canal was greater than 4.0 ft-
NGVD29 and no flow for stages less than this value.
January 2011 City of Miami Phase I - Stormwater Management Master Plan
When the C-7 basin XP-SWMM was being created the C-6 basin model was not
completed. DERM performed test model runs with Hurricane Irene, the "No -Name
Storm" and the November 1998 storm event to establish flow versus stage relationships
and establish rating curves as boundary conditions. Based on these runs, two rating
curves were developed: closed -gate and open -gate condition in relation to the S-27
operating conditions. For the closed -gate condition, the boundary condition indicated
flow into the C-7 basin, out of the C-6 basin for all times where the stage in the Red
Road Canal was greater than 2.25 ft-NGVD29 and no flow for stages Tess than this
value. The flow increased with the increased stage to a maximum of 28 cfs at 3.0 ft-
NGVD29 (the gates do not remain closed for higher stages). For the open -gate
condition, the boundary condition indicated flow out of the C-7 basin, into the C-6 basin
for all times where the stage in the Red Road Canal was greater than 2.5 ft-NGVD and
no flow for stages less than this value. The flow increased with increased stage, but the
rate of increase decreased.
4.9 DERM XP-SWMM Model Version Update
DERM provided hydrologic/hydraulic models for the various basins in the original XP-
SWMM version used in each basin's master plan analysis. For the purposes of the City
of Miami Stormwater Master Plan update, it was deemed necessary to convert these
existing models, to the most recent version of XP-SWMM (Version 2009-11.3, SP3 at
the time of this update). Table 4-3 provides a listing of the model data referenced by
the original name from the electronic files and the XP-SWMM model version used by
DERM for each basin model.
Table 4-3 — Original model data provided by DERM per basin
Basin
XP-SWMM
Engine
Version
Land Use
Original 5-year
model name
Original 100-year
model name
C-3
9.08
Existing
C3-Ex005.xp
C3-Ex100.xp
Future
N/A
N/A
C-4
8.87
Existing
C4_Exist_5.xp
C4_Exist_100.xp
Future
C4_Future_5.xp
C4_Future_100.xp
C-5
9.08
Existing
C5-Ex005.xp
C5-Ex100.xp
Future
N/A
N/A
C-6
9.28
Existing
5-yr_C-6_Exist.xp
C_6_ Exist_100-yr.xp
Future
C-6 FUTURE 5-
— _
yr.xp
C6FUTURE 100-
__—
yr.xp
C-7
9.10
Existing
C7_2005_5.xp
C7_2005_100.xp
Future
N/A
N/A
* N/A represents models not developed by DERM during the preparation of the Basin
Stormwater Master Plan
As described previously, a future conditions model was not deemed necessary for the
C-3, C-5 and C-7 basins due to the relatively insignificant difference in land use
between the existing and future conditions.
4-29
January 2011 City of Miami Phase I - Stormwater Management Master Plan
These original models were converted into the most current version of XP-SWMM
available during the development of this master plan. The following subsections
describe the conversion process undertaken for each of the basin models listed in
Table 4-3 and document the known conversion issues for each model, the resolution
provided, and a comparison of the converted model to the original DERM model output
data. A listing of all conversion issues and resolutions is available, per basin,
Attachment D through H.
Stage, volumetric, and flood duration comparisons were performed for the 14 models
listed in Table 4-3. Stage differences are presented in feet with and the minimum,
maximum and average difference being calculated using absolute values. The average
change in maximum node volume is calculated per node and an average is taken for
the model as a whole with a positive percentage referring to volumes that are higher in
the converted model. Flood duration was also compared and results are presented in
hours with a positive number referring to durations that are longer in the converted
models. Additionally, overall model continuity errors were also presented with no direct
comparison performed.
With respect to the results obtained from the converted models, although certain
manhole nodes showed stages that were significantly higher than the original models,
these nodes appeared to have little impact on the nodes representing basins with
storage and were ignored. In general, stages for the sub -basins within the City of Miami
were within 0.19 ft of the original model and were within acceptable limits. Model
continuity errors also compared favorably to the original models with the exception of
the C-4 basin existing land use models which showed a significant increase in overall
continuity but showed only a minor change in average stages: 0.08 ft overall and 0.03 ft
within the City sub -basins.
4.9.1 C-3 Basin Model Conversion
The original models obtained from DERM for the C-3 basin were developed in
XP-SWMM version 9.08. These models consisted of 102 sub -basins, 256 junctions,
and 359 conduits. The models were successfully converted and were within acceptable
limits once the model outputs were compared. The following subsections detail the
conversion issues encountered during the conversion process and a comparison of the
relevant parameters, which were used to verify concurrence with the DERM calibrated
models.
4.9.1.1 C-3 Conversion Issues and Resolutions
The C-3 basin models were successfully converted from XPSWMM version 9.08 to
XPSWMM version 11.3 without any initial errors during the import process. References
to background files were not rerouted and included the following data files:
o C35 Model Sub -basin Boundaries.dwg
• C35 Model Hydro.dwg
• Rainfall Data
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January 2011 City of Miami Phase I - Stormwater Management Master Plan
In the converted models, several minor modifications were made for the DERM models
to allow the model to run through to completion. The converted models were run with
the hydrology and hydraulics blocks running simultaneously, avoiding the need to create
interface files - this capability was not available in version 9.08. Several nodes were
removed from the runoff layer since there were no subcatchments selected for the given
node and errors presented themselves when the solve command was initiated.
Additionally, all models were solved by removing all nodes and links from the sanitary
layer, and only Runoff and Hydraulics model solutions were executed.
4.9.1.2 C-3 Model Results Comparisons
The converted models compared favorably as shown in the tables presented in this
section. The average difference in model stages for the basins within the City of Miami
showed stages that were within the models expected tolerances and were anticipated
given the difference in version between the DERM models and the current XP-SWMM
version available. Model continuity errors compared favorably and an overall
improvement in continuity was accomplished with the conversion. The following tables
provide DERM basin -wide conversion comparisons, common DERM to City sub -basin
comparisons, and continuity error comparisons for the available existing land use
models.
Table 4-4 — C-3 Basin Results Comparison of Original and Converted XP-SWMM Models - Existing Land
Use
Model
Max Stage Comparison
(feet)
Avg. Change
in Max Node
Volume
Flood Duration Comparison
(hours)
Min. Diff.
Max.
Diff.
Avg.
Diff.
Min. Diff.
Max.
Diff.
Avg. Diff.
5-year, 1-day
0.00
1.94*
0.33
7.21%
0.00
40.75
1.06
100-year, 3-day
0.00
4.68*
0.23
3.10%
0.00
67.46
2.59
*Large stage difference attributed to manhole node
Table 4-5 — C-3 Results Comparison of Sub -basins within the City of Miami - Existing Land Use
Model
Max Stage Comparison
(feet)(hours)
Avg. Change
in Max Node
Volume
Flood Duration Comparison
Min. Diff.
Max.
Diff.
Avg.
Diff.
Min. Diff.
Max.
Diff.
Avg. Diff.
5-year, 1-day
0.00
0.45
0.18
13.95%
0.00
0.00
0.00
100-year, 3-day
0.01
1.75*
0.14
5.64%
0.00
0.00
0.00
*Large stage difference attributed to manhole node
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January 2011
City of Miami Phase I - Stormwater Management Master Plan
Table 4-6 — C-3 Continuity Error Comparison of Original and Converted XP-SWMM Models - Existing
Land Use
Model
Overall Model Continuity Error
ft4
Original
Converted
Original
Converted
5-year, 1-day
-5280425.498
8070.641
-2.2191
0.0041
100-year, 3-day
-6409173.682
5035.278
-1.2614
0.0011
4.9.2 C-4 Basin Model Conversion
The original models obtained from DERM for the C-4 basin were developed in
XP-SWMM version 8.87. These models consisted of 245 sub -basins, 449 junctions,
and 687 conduits. The models were successfully converted and were within acceptable
limits once the model outputs were compared. The following subsections detail the
conversion issues encountered during the conversion process and a comparison of the
relevant parameters which were used to verify concurrence with the DERM calibrated
models.
4.9.2.1 C-4 Conversion Issues and Resolutions
The C-5 basin models were successfully converted from XPSWMM version 8.87 to
XPSWMM version 11.3 without any initial errors during the import process. References
to background files were not rerouted at this time and included the following data file:
• backgrnd.dwg
In the converted models, several minor modifications were made for the DERM models
to allow the model to run through to completion. The converted models were run with
the hydrology and hydraulics blocks running simultaneously, avoiding the need to create
interface files - this capability was not available in version 8.87. Several nodes were
removed from the runoff layer since there were no subcatchments selected for the given
node and errors presented themselves when the solve command was initiated.
Additionally, all models were solved by removing all nodes and links from the sanitary
layer, and only Runoff and Hydraulics model solutions were executed.
4.9.2.2 C-4 Model Results Comparisons
The converted existing land use model stages compared somewhat favorably as shown
in the tables presented in this section. The average difference in model stages for the
basins within the City of Miami showed stages that differed slightly and were expected
given the difference in version between the DERM models and the current XP-SWMM
version available. Although the average stages presented only a slight difference,
model continuity errors did not compare favorably with a significant increase in the
continuity error after the conversion. The following tables provide DERM basin -wide
conversion comparisons, common DERM to City sub -basin comparisons, and continuity
error comparisons for the available existing and future land uses models.
4-32
January 2011
City of Miami Phase I - Stormwater Management Master Plan
Table 4-7 - C-4 Results Comparison of Original and Converted XP-SWMM Models - Existing Land Use
Model
Max Stage Comparison
(feet)
Avg. Change
in Max Node
Volume
Flood Duration Comparison
(hours)
Min. Diff.
Max.
Diff.
Avg.
Diff.
Min. Diff.
Max.
Diff.
Avg. Diff.
5-year, 1-day
0.00
0.00
0.00
0.00%
0.00
0.00
0.00
100-year, 3-day
0.00
3.92*
0.08
2.45%
0.00
0.00
0.00
*Large stage difference attributed to manhole node
Table 4-8 - C-4 Results Comparison of Sub -basins within the City of Miami - Existing Land Use
Model
Max Stage Comparison
(feet)
Avg. Change
in Max Node
Volume
Flood Duration Comparison
(hours)
Min. Diff.
Max.
Diff.
Avg.
Diff.
Min. Diff.
Max.i.
Avg. Diff.
5-year, 1-day
0.00
0.00
0.00
0.00%
0.00
0.00
0.00
100-year, 3-day
0.00
0.09
0.03
8.97%
0.00
0.00
0.00
Table 4-9 - C-4 Continuity Error Comparison of Original and Converted XP-SWMM Models - Existing
Land Use
Model
Overall Model Continuity Error
ft3
%
Original
Converted
Original
Converted
5-year, 1-day
92877916.787
355062521.697
5.3541
18.1751
100-year, 3-day
3175119.611
788843187.376
0.0637
16.4006
The converted future land use models compared favorably as shown in the tables
presented in this section. The average difference in model stages for the basins within
the City of Miami showed negligible differences in stages and were expected given the
difference in version between the DERM models and the current XP-SWMM version
available. Model continuity errors compared favorably and were within acceptable
parameters.
Table 4-10 - C-4 Results Comparison of Original and Converted XP-SWMM Models - Future Land Use
Model
Max Stage Comparison
(feet)
Avg. Change
in Max Node
Volume
Flood Duration Comparison
(hours)
Min. Diff.
Max.
Diff.
Avg.
Diff.
Min. Diff.
Diff.
Avg. Diff.
5-year, 1-day
0.00
2.64
0.09
22.50%
0.00
0.00
0.00
100-year, 3-day
0.00
4.61*
0.14
2.42%
0.00
0.00
0.00
*Large stage difference attributed to manhole node
4-33
January 2011
City of Miami Phase I - Stormwater Management Master Plan
Table 4-11 — C-4 Results Comparison of Sub -basins within the City of Miami - Future Land Use
Model
Max Stage Comparison
(feet)
Avg. Change
in Max Node
Volume
Flood Duration Comparison
(hours)
Min. Diff.
Max.
Diff.
Avg.
Diff.
Min. Diff.
Max.
Avg. Diff.
5-year, 1-day
0.00
0.06
0.02
10.87%
0.00
0.00
0.00
100-year, 3-day
0.00
0.07
0.03
8.15%
0.00
0.00
0.00
Table 4-12 — C-4 Continuity Error Comparison of Original and Converted XP-SWMM Models - Future
Land Use
Model
Overall Model Continuity Error
ft3
%
Original
Converted
Original
Converted
5-year, 1-day
496318392.019
362920326.742
4.4516
3.3080
100-year, 3-day
82673854.755
757991643.280
0.5977
5.5513
4.9.3 C-5 Basin Model Conversion
The original models obtained from DERM for the C-5 basin were developed in
XP-SWMM version 9.08. These models consisted of 33 sub -basins, 113 junctions, and
175 conduits. The models were successfully converted and were within acceptable
limits once the model outputs were compared. The following subsections detail the
conversion issues encountered during the conversion process and a comparison of the
relevant parameters which were used to verify concurrence with the DERM calibrated
models.
4.9.3.1 C-5 Conversion Issues and Resolutions
The C-5 basin models were successfully converted from XPSWMM version 9.08 to
XPSWMM version 11.3 without any initial errors during the import process. References
to background files were not rerouted at this time and included the following data files:
• C35 Model Sub -basin Boundaries.dwg
• Rainfall Data
In the converted models, several minor modifications were made for the DERM models
to allow the model to run through to completion. The converted models were run with
the hydrology and hydraulics blocks running simultaneously, avoiding the need to create
interface files - this capability was not available in version 9.08. Several nodes were
removed from the runoff layer since there were no subcatchments selected for the given
node and errors presented themselves when the solve command was initiated.
Additionally, all models were solved by removing all nodes and links from the sanitary
layer, and only Runoff and Hydraulics model solutions were executed.
4-34
January 2011 City of Miami Phase I - Stormwater Management Master Plan
4.9.3.2 C-5 Model Results Comparisons
The converted models compared favorably as shown in the tables presented in this
section. The average difference in model stages for the basins within the City of Miami
showed stages that were within the models expected tolerances and were expected
given the difference in version between the DERM models and the current XP-SWMM
version available. Model continuity errors compared favorably and were within
acceptable parameters. The following tables provide DERM basin -wide conversion
comparisons, common DERM to City sub -basin comparisons, and continuity error
comparisons for the available existing land use models.
Table 4-13 — C-5 Results Comparison of Original and Converted XP-SWMM Models - Existing Land Use
Model
Max Stage Comparison
(feet)
Avg. Change
in Max Node
Volume
Flood Duration Comparison
(hours))
Min. Diff.
Max.
Diff. g
Min. Diff.
Max.
Avg. Diff.
5-year, 1-day
0.00
8.48*
0.56
6.62%
0.00
2.47
0.06
100-year, 3-day
0.00
6.85*
0.18
1.57%
0.00
2.30
0.11
*Large stage difference attributed to manhole node
Table 4-14 — C-5 Results Comparison of Sub -basins within the City of Miami - Existing Land Use
Model
Max Stage Comparison
(feet)
Avg. Change
in Max Node
Volume
Flood Duration Comparison
(hours)
Min. Diff.
Max.
Diff.
Avg.
Diff.
Min. Diff.
Max.
Diff.
Avg. Diff.
5-year, 1-day
0.00
1.17
0.19
12.59%
0.00
0.00
0.00
100-year, 3-day
0.00
0.09
0.02
1.36%
0.00
0.00
0.00
Table 4-15 — C-5 Continuity Error Comparison of Original and Converted XP-SWMM Models - Existing
Land Use
Model
Overall Model Continuity Error
ft3
Original
Converted
Original
Converted
5-year, 1-day
-210725.548
577114.007
-0.6852
1.3165
100-year, 3-day
1612750.685
2275139.313
2.1409
2.3385
4.9.4 C-6 Basin Model Conversion
The original models obtained from DERM for the C-6 basin were developed in
XP-SWMM version 9.24. These models consisted of 310 sub -basins, 521 junctions,
and 784 conduits. The models were successfully converted and were within acceptable
limits once the model outputs were compared. The following subsections detail the
conversion issues encountered during the conversion process and a comparison of the
IL
4-35
January 2011 City of Miami Phase I - Stormwater Management Master Plan
relevant parameters which were used to verify concurrence with the DERM calibrated
models.
4.9.4.1 C-6 Conversion Issues and Resolutions
The C-6 basin models were successfully converted from XPSWMM version 9.24 to
XPSWMM version 11.3 without any initial errors during the import process. This basin's
models did not contain references to background files were.
In the converted models, several minor modifications were made for the DERM models
to allow the model to run through to completion. The converted models were run with
the hydrology and hydraulics blocks running simultaneously, avoiding the need to create
interface files - this capability was not available in version 9.24. Several nodes were
removed from the runoff layer since there were no subcatchments selected for the given
node and errors presented themselves when the solve command was initiated.
Additionally, all models were solved by removing all nodes and links from the sanitary
layer, and only Runoff and Hydraulics model solutions were executed.
4.9.4.2 C-6 Model Results Comparisons
The converted models compared favorably as shown in the tables presented in this
section. The average difference in model stages for the basins within the City of Miami
showed stages that were almost identical to the original models provided by DERM.
Model continuity errors also compared favorably. The following tables provide DERM
basin -wide conversion comparisons, common DERM to City sub -basin comparisons,
and continuity error comparisons for the available existing and future land uses models.
Table 4-16 — C-6 Results Comparison of Original and Converted XP-SWMM Models - Existing Land Use
Model
Max Stage Comparison
(feet)
Avg. Change
in Max Node
Volume
Flood Duration Comparison
(hours)
Min. Diff.
Max.
Diff.
Avg.
Diff.
Min. Diff.
Diff. Max.
Avg. Diff.
5-year, 1-day
0.00
0.11
0.01
0.36%
0.00
0.00
0.00
100-year, 3-day
0.00
0.00
0.00
0.00%
0.00
0.00
0.00
Table 4-17 — C-6 Results Comparison of Sub -basins within the City of Miami - Existing Land Use
Model
Max Stage Comparison
(feet)
Avg. Change
in Max Node
Volume
Flood Duration Comparison
(hours)
Min. Diff.
Max.
Diff.
Avg.
Diff.
Min. Diff.
Max.i
Avg. Diff.
5-year, 1-day
0.00
0.04
0.01
1.54%
0.00
0.00
0.00
100-year, 3-day
0.00
0.00
0.00
0.00%
0.00
0.00
0.00
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January 2011
City of Miami Phase I - Stormwater Management Master Plan
Table 4-18 - C-6 Continuity Error Comparison of Original and Converted XP-SWMM Models - Existing
Land Use
Model
Overall Model Continuity Error
ft3
%
Original
Converted
Original
Converted
5-year, 1-day
16362879.882
16614324.663
0.3549
0.3607
100-year, 3-day
65396206.299
58381631.487
1.0649
0.9474
Table 4-19 - C-6 Results Comparison of Original and Converted XP-SWMM Models - Future Land Use
Model
Max Stage Comparison
(feet)
Avg. Change
in Max Node
Volume
Flood Duration Comparison
(hours))
Min. Diff.
Max.
Diff.
Avg.
Diff.
Min. Diff.
Max.
Diff.
Avg. Diff.
5-year, 1-day
0.00
0.00
0.00
0.00%
0.00
0.00
0.00
100-year, 3-day
0.00
0.00
0.00
0.00%
0.00
0.00
0.00
Table 4-20 - C-6 Results Comparison of Sub -basins within the City of Miami - Future Land Use
Model
Max Stage Comparison
(feet)
Avg. Change
in Max Node
Volume
Flood Duration Comparison
(hours)
Min. Diff.
Max.
Diff.
Avg.
Diff.
Min. Diff.
Max.
Diff.
Avg. Diff.
5-year, 1-day
0.00
0.00
0.00
0.00%
0.00
0.00
0.00
100-year, 3-day
0.00
0.00
0.00
0.00%
0.00
0.00
0.00
Table 4-21 - C-6 Continuity Error Comparison of Original and Converted XP-SWMM Models - Future
Land Use
Model
Overall Model Continuity Error
ft3
%
Original
Converted
Original
Converted
5-year, 1-day
19947093.086
19594372.876
0.4331
0.4258
100-year, 3-day
51878185.340
61521451.439
0.8494
1.0091
4.9.5 C-7 Basin Model Conversion
The original models obtained from DERM for the C-7 basin were developed in
XP-SWMM version 9.10. These models consisted of 154 sub -basins, 258 junctions,
and 406 conduits. The models were successfully converted and were within acceptable
limits once the model outputs were compared. The following subsections detail the
4-37
January 2011 City of Miami Phase I - Stormwater Management Master Plan
conversion issues encountered during the conversion process and a comparison of the
relevant parameters which were used to verify concurrence with the DERM calibrated
models.
4.9.5.1 C-7 Conversion Issues and Resolutions
The C-7 basin models were successfully converted from XPSWMM version 9.10 to
XPSWMM version 11.3 without any initial errors during the import process. This basin's
models did not contain references to background files were.
In the converted models, several minor modifications were made for the DERM models
to allow the model to run through to completion. The converted models were run with
the hydrology and hydraulics blocks running simultaneously, avoiding the need to create
interface files - this capability was not available in version 9.10. Several nodes were
removed from the runoff layer since there were no subcatchments selected for the given
node and errors presented themselves when the solve command was initiated.
Additionally, all models were solved by removing all nodes and links from the sanitary
layer, and only Runoff and Hydraulics model solutions were executed.
4.9.5.2 C-7 Model Results Comparisons
The converted models compared favorably as shown in the tables presented in this
section. The average difference in model stages for the basins within the City of Miami
showed stages that were within the models expected tolerances and were anticipated
given the difference in version between the DERM models and the current XP-SWMM
version available. Model continuity errors also compared favorably. The following tables
provide DERM basin -wide conversion comparisons, common DERM to City sub -basin
comparisons, and continuity error comparisons for the available existing land use
models.
Table 4-22 — C-7 Basin Results Comparison of Original and Converted XP-SWMM Models - Existing
Land Use
Model
Max Stage Comparison
(feet)
Avg. Change
in Max Node
Volume
Flood Duration Comparison
(hours)
Min. Diff.
Max.
Diff.
Avg.
Diff.
Min. Diff.
Diff
Avg. Diff.
5-year, 1-day
0.00
0.00
0.00
0.00%
0.00
0.00
0.00
100-year, 3-day
0.00
0.26
0.04
1.00%
0.00
23.99*
0.09
* - node cg1, only node to experience difference in flood duration. Refer to Attachment E.
Table 4-23 — C-7 Results Comparison of Sub -basins within the City of Miami - Existing Land Use
Model
Max Stage Comparison
(feet)
Avg. Change
in Max Node
Volume
Flood Duration Comparison
(hours)
Min. Diff.
Max
Mfr.
Avg.
Diff.
Min. Diff.
Diff
Avg. Diff.
5-year, 1-day
0.00
0.00
0.00
0.00%
0.00
0.00
0.00
100-year, 3-day
0.00
0.05
0.02
1.49%
0.00
0.00
0.00
4-38
January 2011
City of Miami Phase I - Stormwater Management Master Plan
Table 4-24 — C-7 Continuity Error Comparison of Original and Converted XP-SWMM Models - Existing
Land Use
Model
Overall Model Continuity Error
ft3
°k
Original
Converted
Original
Converted
5-year, 1-day
-1850734.491
227086.719
-0.3425
0.0064
100-year, 3-day
-1085688.287
-534737.793
-0.0803
-0.0420
4.10 Modeling of Existing Conditions Conclusion & Recommendations
The DERM Stormwater Master Plans for the C-3, C-4, C-5, C-6 and C-7 offered well
documented model development information as well as complete and functioning
electronic versions of their respective XP-SWMM models. Each DERM basin
stormwater master plan provided sufficient detail regarding the development,
calibration, and verification of the individual models available and the assumptions
made for each basin.
With regards to basins with predominantly urbanized areas such as those within the City
of Miami, DERM typically utilized only an existing land use model. These models, which
included the C-3, C-5 and C-7 basins, also incorporated stormwater management
improvement projects and canal dredging projects which were completed just prior to
the commencement of the DERM stormwater master plans into these models. For
these basins, only an existing land use model was analyzed further.
With regards to the C-4 basin, the future land use model incorporates numerous
stormwater improvement projects which are currently in place. Utilizing the existing
land use model was not representative of the stormwater management structures
present today. For these basins, only the future land use models were analyzed further.
As for the C-6 basin, Tess than 0.16 ft of difference existed between the existing and
future land use conditions for 35 of the 43 sub -basins that fall within the City. Six of the
eight remaining basins showing differences of greater than 0.16 ft were highly urbanized
sub -basins which possibly incorporate improvements that are not clearly defined in the
report which may result in the lower stages observed. The remaining two sub -basins
have large undeveloped parcels which appear to have been converted to urbanized
areas resulting in increases in runoff and stages. Additionally, NFIP may request the
analysis of existing and future land use conditions even though the City of Miami is
almost completely built out and changes in land use would result in negligible
differences. For the C-6 basin, due to NFIP potential requirements, and the overall
coverage area of this basin within the City, both the future and existing land use models
will be carried forward in the analysis.
4-39
January 2011 City of Miami Phase I - Stormwater Management Master Plan
The model conversions yielded functioning models that serve as reliable calibrated and
verified models for use in the activities that will be undertaken for the City of Miami
Stormwater Master Plan Update. Conversions beyond the presently available XP-
SWMM Version 2009-11.3, SP3 were not performed for this project. Any updates of the
converted models to a future version would require a similar assessment to that which
was already performed.
With respect to the results obtained from the converted models, in general, stages for
the sub -basins within the City of Miami were within 0.19 ft of the original model and
were within acceptable limits. Model continuity errors also compared favorably to the
original models with the exception of the C-4 basin existing land use models which
showed a significant increase in overall continuity but showed only a minor change in
average stages 0.08 ft overall and 0.03 ft within the City sub -basins. Additionally, it is
anticipated that the future land use model will be used for this basin which will negate
the use of the existing land use model.
As a result, Table 4-25 provides a listing of the XP-SWMM models that will be used to
further develop the City of Miami's Stormwater Master Plan Update.
Table 4-25 — XP-SWMM Basin Models to be Used
Basin
Land Use
version
Converted 5-year
model name
Converted 100-year
model name
C-3
Existing
C3_ExLU_005.xp
C3_ExLU_100.xp
C-4
Future
C4_FuLU_005.xp
C4_FuLU_100.xp
C-5
Existing
C5_ExLU_005.xp
C5_ExLU_100.xp
C-6
Existing
C6_ExLU_005.xp
C6_ExLU_100.xp
Future
C6_FuLU 005.xp
C6 FuLU 100.xp
C-7
Existing
C7_ExLU_005.xp
C7_ExLU_100.xp
Additionally, based on the complexity of the translation process for City of Miami sub -
basins to DERM sub -basins, presenting and referencing result data using the DERM
sub -basin delineations will provide the best possible way of interpreting and utilizing the
model result data for this Stormwater Master Plan Update.
January 2011
City of Miami Phase I - Stormwater Management Master Plan
5.0
IDE+
RAN'KYNG"OF .PROBLEM
AREAS
5.1 DERM Flood Problem Area Ranking & Flood Protection Level of Service
Procedure
DERM established procedures and criteria, as part of their stormwater master planning
activities, to identify problem areas, rank problem areas, and establish flood protection
level of service using the hydrologic/hydraulic modeling results for the 5-, 10-, 25-, 50-
and 100-year design storm events. These procedures and criteria were documented in
Part I, Volume 3, "Stormwater Planning Procedures," March 1995 and were applied by
DERM to the C-3, C-4, C-5, C-6 and C-7 basins. In this methodology, the ranking of
flooding problem areas is related to the defined floodplain level of service (FPLOS) as
follows:
1. All structures (commercial, residential, and public) should be flood -free during the
100-year storm event.
2. Principal arterial roads, including major evacuation routes, should be passable
during the 100-year storm event.
3. All canals should operate within their banks during their respective design floods.
(Primary canal design criteria vary from 10-year to 100-year events and are
described for the major drainage basins in the Miami -Dade County
Comprehensive Plan.) The C-3 and C-5 Canals are designed for the 10-year
storm event, the C-7 Canal is designed for the 100-year storm event, and the C-4
and C-6 Canals are designed for greater than a 100-year storm event.
4. Minor arterial roads (up to 4-lanes) should be passable during the 10-year storm
event.
5. Collector and local residential streets should be passable during the 5-year storm
event, as per current Miami -Dade County Drainage Policy.
The severity of flooding within each sub -basin is determined through the calculation of a
flooding problem severity score (FPSS), which is a function of five "severity indicators"
that are directly related to the FPLOS criteria described previously. These severity
indicators are defined and summarized below. Each of these indicators also has an
assigned "weighing factor" (WF), which is related to the relative importance of the
flooding severity indicator as shown as follows:
Sub -basin Flooding Severity Indicators
1. NS: Number of structures flooded by the 100-year flood, which can include
commercial, residential, and public buildings. All structures and/or buildings are
considered equivalent, regardless of their size or value. (WF = 4)
2. MER: Miles of principal arterial roads, including major evacuation routes, which
are impassable during the 100-year flood. DERM has defined that a principal
arterial road is considered impassable if the depth of flooding exceeds 8 inches
above the crown of the road during the 100-year design event. (WF = 4)
3. BM: Miles of canal with out -of -bank flow, expressed in bank -miles. The length
of canal flooding shall be determined for the design storm event originally used to
design the canal. (WF = 3)
January 2011 City of Miami Phase I - Stormwater Management Master Plan
4. MMAS: Miles of minor arterial roads impassable during the 10-year flood. DERM
has defined that a minor arterial road is considered impassable if the depth of
flooding exceeds the crown of the road during the 10-year design event. (WF = 2)
5. MCLRS: Miles of collector and local residential streets impassable during 5-
year flood. DERM has defined that collector and local residential streets are
considered impassable if the depth of flooding exceeds the crown of the road
during the 5-year design storm event. (WF = 1)
The severity indicators are rated by an exceedance (E) value pursuant to the following
DERM severity score listed in the following table:
Depth of Flooding Above the FPLOS E
Less than or equal to 6 inches 1
Greater than 6 inches and less than or equal to 12 inches 2
Greater than 12 inches 3
Given the definitions for the flooding severity indicators (NS, MER, BM, MMAS, and
MCLRS), WF and E, the FPSS for each sub -basin is calculated using the following
formula, where E(;) through E(v) relates to the degree of exceedance for each of the five
severity indicators as follows:
FPSS = [4xE(;)xNS] +[4xEt;;)xMER] +[3xEp;;)xBM] +
[2 x Er;„) x MMAS] + [1 x E(v) x MCLRS]
Once the severity score is calculated per basin, the sub -basin with the highest FPSS is
given a ranking value of 1. Subsequent FPSS scores are then given ranking values of 1
through X. Sub -basins with equivalent FPSS are given the same ranking value. This
approach will yield the basins with the highest flooding problems based on a
quantifiable and mathematical basis.
The actual flood protection level -of -service (FPLOS) provided within a particular sub -
basin is dependent upon the number of FPLOS criteria that have been met, as defined
previously. DERM established a FPLOS rating by assigning a letter values based on the
following schedule:
FPLOS Number of Indicators/ FPLOS Criteria Met
A all five met
B four of the five
C three of the five
D two of the five
E one or none of the five
5.2 City of Miami Revised Flood Problem Area Ranking & Flood Protection
Level of Service Procedure
As described in Section 2, DERM's procedure utilized parameters that were dependent
on the peak flood elevations for the 5-, 10-, 25-, 50- and 100-year design storm events.
For Phase I of the City of Miami Stormwater Management Master Plan Update, only the
5- and 100-year design storm events were analyzed. Therefore, various parameters .--
5-2
January 2011 City of Miami Phase I - Stormwater Management Master Plan
were removed from the ranking procedure and replaced with other parameters that will
help identify critical sub -basins using specific flood protection factors representative of
the unique features of the City. The parameters omitted from the ranking procedure
developed by DERM include:
1. BM: Miles of canal with out -of -bank flow, expressed in bank -miles. Design
event varied by individual canal design event.
2. MMAS: Miles of minor arterial roads impassable during the 10-year flood.
The parameters omitted used design storm events other than the 5- and 100-year which
were not analyzed for this SWMMP.
In lieu of the omitted parameters, additional parameters were incorporated into the
analysis and FPSS equation to provide additional quantifiable flooding factors for the
sub -basin ranking. As a result, it was determined that the following parameters would
provide a good indication of the flood severity within a given sub -basin:
1. DEM: Total area experiencing flooding during the 100 storm event in 5 acre
units.
2. REP: Number of properties in the repetitive loss database within the sub -basin
for 2009.
The DEM parameter was incorporated into the scoring equation in the same fashion as
the other parameters quantified - using a severity score based on depth of flooding and
a weighing factor as described in the following section. The REP parameter did not
take into account the depth of flooding or a severity score at a given location, but it was
quantified per basin and given a high weighing factor due to its importance.
Similar to DERM's ranking procedure, the ranking of flooding problem areas is related to
the defined floodplain level of service (FPLOS) as follows:
1. All structures (commercial, residential, and public) should be flood -free during the
100-year storm event.
2. Principal arterial roads, including major evacuation routes, should be passable
during the 100-year storm event.
3. Collector and local residential streets should be passable during the 5-year storm
event, as per current Miami -Dade County Drainage Policy.
4. Total area flooded within a basin will be minimized during the 100-year storm
event.
5. The total number of repetitive loss propertied will be minimized.
In keeping with the DERM procedure, the severity of flooding within each sub -basin is
determined through the calculation of a flooding problem severity score (FPSS), which
is a function of the five revised "severity indicators" that are directly related to the
FPLOS criteria described previously. These severity indicators are defined and
summarized below. Each of these indicators also has an assigned "weighing factor"
(WF), which is related to the relative importance of the flooding severity indicator.
January 2011 City of Miami Phase I - Stormwater Management Master Plan
Sub -basin Flooding Severity Indicators
1. NS: Number of structures flooded by the 100-year flood, which can include
commercial, residential, and public buildings. All structures and/or buildings are
considered equivalent, regardless of their size or value. (WF = 4)
2. DEM: Total area experiencing flooding for the 100-year flood in 5 acre units.
(WF = 2)
3. MER: Miles of principal arterial roads, including major evacuation routes, which
are impassable during the 100-year flood. DERM has defined that a principal
arterial road is considered impassable if the depth of flooding exceeds 8 inches
above the crown of the road during the 100-year design event. (WF = 4)
4. MCLRS: Miles of collector and local residential streets impassable during 5-year
flood. DERM has defined that collector and local residential streets are
considered impassable if the depth of flooding exceeds the crown of the road
during the 5-year design storm event. (WF = 1)
5. REP: Number of repetitive loss properties within the sub -basin in 2009. (WF =
100)
The REP parameter was given a high WF due to the relatively small number of
properties listed in the database. By giving REP a WF of 100, this increased the value
associated with this parameter and promoted the basins with larger numbers of
repetitive loss properties.
Also in keeping with the DERM procedures, the severity indicators are rated by an
exceedance (E) value pursuant to the following DERM severity score listed in the table
below for all values, except the REP indicator.
Depth of Flooding Above the FPLOS E
Less than or equal to 6 inches 1
Greater than 6 inches and Tess than or equal to 12 inches 2
Greater than 12 inches 3
Given the definitions for the flooding severity indicators (NS, DEM, MER, MCLRS and
REP), WF and E, the FPSS for each sub -basin is calculated using the following formula,
where Et;) through Eov) relates to the degree of exceedance for each of the applicable
severity indicators.
FPSS = [4xE0)xNS] +[2xEvi)xDEM] +[4xEpoifxMER]+
[1 x E(;v) x MCLRS] + [100 x REP]
Once the severity score is calculated per basin, the sub -basin with the highest FPSS is
given a ranking value of 1. Subsequent FPSS scores are then given ranking values of 1
through X. Sub -basins with equivalent FPSS are given the same ranking value. This
approach will yield the basins with the highest flooding problems based on a
quantifiable and mathematical basis.
The actual flood protection level -of -service (FPLOS) provided within a particular sub -
basin is dependent upon the number of FPLOS criteria that have been met, as defined
January 2011 City of Miami Phase I - Stormwater Management Master Plan
previously. DERM established a FPLOS rating by assigning a letter values based on
the following schedule.
FPLOS Number of Indicators/ FPLOS Criteria Met
A all five met
B four of the five
C three of the five
D two of the five
E one or none of the five
An indicator was met when the value for a given FPSS was zero. For this SWMMP, the
same FPLOS grading system was followed.
5.3 Quantifying Methodology for Sub -basin Flooding Severity. Indicators
The various flood severity indicators of the FPSS equation outlined in Section 3.1 were
quantified using standard GIS tools to facilitate the analysis of the resulting model data
versus the digital elevation model (DEM) developed as part of this SWMMP and other
entities. The DEM created for this SWMMP is a raster based bare earth topographic
elevation model derived from the Miami -Dade County provided TIN which was
developed using Light Detection And Ranging (LiDAR) topographic data points provided
by DERM for the C-3, C-4, C-5, C-6 and C-7 basins.
This TIN was converted into a raster based DEM with cell dimensions of 25' by 25' in
GIS using ESRI's Spatial Analyst. This cell size provided sufficient resolution to
represent the overall topographic characteristics of the City while still remaining
manageable in the GIS environment - see Figure 5-1. Individual roadways are clearly
visible and general topographic trends can be seen for all areas within the City.
The first step undertaken to quantify the various parameters in the FPSS equation was
to prepare a buffered boundary of the City of Miami. A 1,000-ft buffer was defined
around the City of Miami in order to ensure that all entities (structures and roadways)
within the City's limits were included in the quantities. This buffer was used to clip the
property appraisers lot coverage, the roadway network, and the DEM.
Secondly, the polyline roadway network was utilized to determine the values associated
with the roadway network - the MER and MCLRS indicators. The GIS roadway
coverage represented the approximated centerline of each roadway. Each road had a
number classification for the type of road, with values of zero through three being
principal arterials or highways and values four through nine being collectors or local
roads. This number classification allowed each segment of roadway to be classified
under either the MER or MCLRS severity indicator.
AnK.
5-5
January 2011
City of Miami Phase I - Stormwater Management Master Plan
Figure 5-1 — Raster based DEM
Figure 5-2 — Roadways lines to points
This roadway network was then projected to the raster based DEM in order to give each
line elevation data along the line. When the projection is performed, numerous vertices
are inserted in each line at points closest to the center of each raster cell. These
polylines can then be broken up into individual segments, each with a beginning and
January 2011 City of Miami Phase I - Stormwater Management Master Plan
end point, a specific X, Y, and Z value at both ends, and a segment length. In order for
each line segment to be counted once, either the beginning or end point can only be
used to represent a given line segment - in this case, the beginning point was used -
see Figure 5-2. Each segment was broken into individual segments approximately 25-
ft in length and each segment was represented by a point with the actual calculated
length as an attribute.
Next, the number of structures flooded, or NS, was calculated using the existing
property appraisers coverage acquired from Miami -Dade County. It was observed
during a cursory review of the property appraiser coverage that a number of properties
were listed with a zero value in the square footage of the building and a zero value for
the year built. This was often the case for open lots with no buildings. In order to omit
these properties in the NS count, all properties showing a zero for year built and a zero
for the building square footage were eliminated from the coverage and the remaining
properties were used for the NS count. Inconsistencies remained within the coverage,
but any efforts to correct the count further would necessitate a lengthy review of each
polygon and was not a feasible solution for this SWMMP.
Figure 5-3 — Property polygons to points
The resulting coverage was converted to a point file by converting the polygons
representing the property limits to a point located at the centroid of the polygon. In the
vast majority of the cases, the point lied within the building footprint and was an
excellent representation of the property - see Figure 5-3. In certain cases, due to
irregular lot shapes, the point resided somewhere inside the property limits but still
relatively close to the building footprint. These exceptions were negligible considering
the number of properties accounted for in this analysis (over 37,000 properties).
5-7
January 2011 City of Miami Phase I - Stormwater Management Master Plan
The Z value, or the finished floor elevation, for these properties was estimated using the
same approach used by DERM in the various stormwater management master plans.
This approach estimated the finished floor elevation of a lot based on the closest
adjacent crown of road elevation plus eight (8) inches. For this SWMMP, this was done
in GIS by performing a spatial join of the property points and the roadway points - see
Figure 5-2. This resulted in the property points being assigned the attribute data from
the closest roadway point to it.
The DEM was also converted into a point coverage to help quantify the area which was
inundated under the two modeled storm events. Each raster cell was given a point at
the center of the cell, with the point containing the cell's topographic elevation - see
Figure 5-4. Each point represented 625 sq-ft of topographic area within a basin. These
points were then joined spatially, in GIS, with the sub -basin coverage which contained
the peak elevations from the two scenarios analyzed.
Figure 5-4 — DEM to Points
The REP parameter, which represents the 2009 repetitive Toss properties, was counted
by joining the points representing the location of the property with the sub -basin
delineation and totaled for each sub -basin.
Each of the point coverages representing the various parameters were joined with the
model sub -basin delineations in order to provide each point with a sub -basin and DERM
basin location. This enabled the grouping of various parameters within their respective
sub -basins.
The attribute tables from these various coverages (DEM, Properties, Roadways, REP)
were then imported into Microsoft Access databases in order to process the information
gathered within the tables and arrive at a proper count of the various elements making
5-8
January 2011 City of Miami Phase I - Stormwater Management Master Plan
up the FPSS. These parameters were only counted where they fell within the City's
limits, i.e., if a basin extended beyond the limits of the City, the points representing the
various parameters outside the City limits were excluded from the quantification. Each
table contained data such as DERM sub -basin name, point elevation, and other
pertinent data necessary for the proper grouping and summarizing of the entities they
represent.
5.4 Flood Problem Area Ranking Results & Flood Protection Level of
Service Results
The flood severity result data was collected under two scenarios and two storm events.
The models used under each scenario and event are listed in Table 5-1. The only
difference between the Existing and Future scenarios under this SWMMP is the model
used for the C-6 basin and the reason for using these models was discussed previously.
Table 5-1 — XP-SWMM Basin Models Used by Scenarios
Basin
Existing. Scenario
5-year, Event
Future Scenario
5-year Event
Existing Scenario
100-year Event
Future Scenario
100-year Event
C-3
C3_ExLU_005.xp
C3_ExLU_005.xp
C3_ExLU_100.xp
C3_ExLU_100.xp
C-4
C4_FuLU_005.xp
C4_FuLU_005.xp
C4_FuLU_100.xp
C4_FuLU_100.xp
C-5
C5_ExLU_005.xp
C5_ExLU_005.xp
C5_ExLU_100.xp
C5_ExLU_100.xp
C-6
C6_ExLU_005.xp
C6_FuLU_005.xp
C6_ExLU_100.xp
C6_FuLU_100.xp
C-7
C7_ExLU_005.xp
C7_ExLU_005.xp
C7_ExLU_100.xp
C7_ExLU_100.xp
Flood plain data for each scenario was prepared in raster format in order to show the
location and severity of the flood conditions developed under this analysis. Flooding
was represented in three colors corresponding to the severity indicators assigned to a
specific flood conditions. These conditions were:
• Green - flooding is greater than zero and less than or equal to 6-inches
• Yellow - flooding is greater than 6-inches and less than or equal to 12-inches
• Red - flooding is greater than 12-inches
Figure 5-5 shows a sample area of the flood plain mapping developed for this SWMMP
with some transparency added to the raster cells. Attachment K contains maps
showing the location and severity of flooding for the various scenarios and storm events
modeled.
January 2011
City of Miami Phase I - Stormwater Management Master Plan
Figure 5-5 — Sample of Flood Plain Mapping Results
The FPSS results are presented in Attachment L showing each sub -basins severity
score by severity indicator, the ranking of the sub -basin within that severity indicator,
and the overall composite ranking of the sub -basins that lie within the limits of the City
of Miami. Table 5-2 and Table 5-3 present the 15 basins with the highest FPSS.
Table 5-2 — Top 15 Basins for the Existing Condition Models based on the FPSS
Sub -basin
DERM
Basin
FPSS
Ranks
FPLOS
CC6-N-12
C-6 Basin
13723
1
E
CC7-S-25
C-7 Basin
12021
2
E
CC7-S-21
C-7 Basin
10691
3
E
C6-N-17
C-6 Basin
9620
4
E
CC7-S-24
C-7 Basin
9502
5
E
C4-S-17
C-4 Basin
9292
6
E
CC6-N-11
C-6 Basin
8634
7
E
C6-S-12
C-6 Basin
7549
8
E
CC4-S-21
C-6 Basin
6295
9
E
CC7-S-26
C-7 Basin
5513
10
E
C4-S-18
C-4 Basin
5402
11
E
C4-S-23
C-4 Basin
5051
12
E
C5-S5-3
C-5 Basin
4596
13
D
CC6-S-8
C-6 Basin
3902
14
E
DA1-SE-2
DA-1 Basin
3388
15
D
5-10
January 2011
City of Miami Phase 1- Stormwater Management Master Plan
Table 5-3 — Top 15 Basins for the Future Condition Models based on the FPSS
.Sub -basin
DERM
Basin
FPSS
Ranks
FPLOS
CC6-N-12
C-6 Basin
13927
1
E
CC7-S-25
C-7 Basin
12021
2
E
CC7-S-21
C-7 Basin
10691
3
E
C6-N-17
C-6 Basin
9799
4
E
CC7-S-24
C-7 Basin
9502
5
E
C4-S-17
C-4 Basin
9292
6
E
CC6-N-11
C-6 Basin
8925
7
E
C6-S-12
C-6 Basin
8141
8
E
CC4-S-21
C-6 Basin
6295
9
E
CC7-S-26
C-7 Basin
5513
10
E
C4-S-18
C-4 Basin
5402
11
E
C4-S-23
C-4 Basin
5051
12
E
C5-S5-3
C-5 Basin
4596
13
D
CC6-S-8
C-6 Basin
4143
14
E
DA1-SE-2
DA-1 Basin
3388
15
D
Additionally, Attachment M presents the ranking results in maps coded by .the FPSS
rank developed for this SWMMP. Table 5-2, Table 5-3, and Attachment M also
provide the FPLOS letter value for each basin. In general, it is improbable for a basin to
have met all five parameters in the FPLOS scoring system. In most basins, a score of
D or E was given which was a result of only one or two parameters being met,
respectively.
5.4.1 Existing versus Future Conditions Comparison
A comparison was performed on the ranking results to assess the difference in the
basin rankings and flood stages.
It was noted that, with regards to the ranking of the basins, basins ranked 1 through 19
followed the same ranking in both the existing and future conditions - this can be seen
in Table 5-2 and Table 5-3. Basins CC6-S-7, CC6-S-1, and CC6-N-14 showed the
largest change in rank with a position change of 7, 10, and 15. The remaining basins
either remained in the same location or only experienced an average change in rank of
one position up or down.
Additionally, the difference between the existing and future condition model scenarios in
this SWMMP update are based on which version of the DERM C-6 Basin model was
used to compile and process results for the ranking process. As a result, the only real
differences between the two scenarios is the peak stages experienced in the C-6 sub -
basins. An absolute difference under 2 inches was observed between the existing and
future conditions models of the DERM C-6 Basin for the majority of the 35 sub -basins
that fall within the City's limits - this is typically within the tolerances of the XPSWMM
model. Five basins showed an absolute stage difference of approximately 4 inches.
Four basins showed an absolute difference of more than 4 inches. The stage increases
shown in Table 5-4 for two of these basins can be attributed to a change in land use
January 2011
City of Miami Phase I - Stormwater Management Master Plan
from undeveloped to developed land (CC6-S-1 and C6-S-14). The stage reductions
may be attributed to implementation of stormwater management systems within the
basin based on land use.
Table 5-4 — Stage Comparison between Existing and Future conditions Models for the C-6 Basin
Sub -basin
Stage Difference*
Basin Makeup
CC6-S-1
1.22
Golf Course
C6-S-14
0.4
40% undeveloped
CC6-S-7
-0.47
Residential Developed
CC6-N-14
-0.64
Residential Developed
' Negative means that stages decreased in the future and the converse with positive numbers.
Due to the minor difference in stages between the existing and future conditions models
for the majority of the sub -basins within the C-6 Basin and the makeup of the basins
showing a relative increase in stages, it is recommended to proceed with this SWMMP
Update analysis of the City of Miami using the C-6 basin future conditions model.
5.5 Identification & Ranking Procedures Conclusions & Recommendations
The ranking procedure developed by DERM were applicable in this SWMMP update
and provide consistent results. The additional parameters incorporated into the FPSS
equation provided additional items that were consistent with basin flooding and
quantifiable using XPSWMM result data and GIS.
The results and rankings were also consistent with the results expected after
discussions with City staff. Flooding during the 5- and 100-year storm events were
shown in areas where flooding is typically experienced within the City. Low Tying areas
clearly fall within the limits of the 5- and 100-year flood plains and properties, roadways,
and topographic areas can be clearly quantified using these flood plains.
Additionally, based on the FPSS scores, rankings, and resulting stage data, it was
recommended and agreed upon with City staff that this City of Miami SWMMP Update
would proceed with the remaining tasks using the C-6 basin future conditions model as
the baseline condition model for the remaining activities. This recommendation is
based on the relatively minor differences within the majority of the sub -basins. Table
5-5 lists the models and revised names that are to be used for the remaining tasks of
this City of Miami SWMMP Update.
Table 5-5 — XP-SWMM Basin Models Used by Scenarios
Basin
Future. Scenario 5-year'Event•
Future Scenario 100=year Event
C-3
C3_ExLU_005.xp
C3_ExLU_100.xp
C-4
C4_FuLU_005.xp
C4_FuLU_100.xp
C-5
C5_ExLU_005.xp
C5_ExLU_100.xp
C-6
C6_FuLU_005.xp
C6_FuLtJ_100.xp
C-7
C7_ExLU_005.xp
C7_ExLU_100.xp
January 2011
City of Miami Phase I - Stormwater Management Master Plan
6.0 HYDROLOGIC & HYDRAULIC MODELING OF
EXISTING & FUTURE CONDITION LAND USES WITH
CITY FLOOD PROTECTION PROJECTS COMPLETED,
UNDER CONSTRUCTION, & UNDER DESIGN
The City of Miami provided project information for a total of 47 projects. These projects
fell into four status categories - Constructed or Under Construction, Under Design,
Outside of Phase 1 SWMMP Limits, and No Drainage Improvements noted - see Table
6-1. An additional four stormwater pump stations were also incorporated into the
models which were not included in these project totals.
Table 6-1 — Project Status Totals
Status
Number of Projects
Model Scenario
Constructed or Under Construction
31
Construction
Under Design
4
Under Design
Outside of Phase 1 Limits
8
---
No Drainage Improvements noted
4
Total
47
As described previously, the models to be further improved and used to analyze the
City's stormwater management and flood protection systems were those models
referred to as the Future Scenario models and will now be referred to as the Baseline
scenario models. These models include the XP-SWMM models listed in Table 6-2.
Table 6-2 — XP-SWMM Basin Models Used in the Baseline Scenario
Basin
Baseline Scenario Models
5-year Event
Baseline Scenario models
100-year Event
C-3
C3 ExLU_005.xp
C3_ExLU_100.xp
C-4
C4_FuLU 005.xp
C4 FuLU 100.xp
C-5
C5 ExLU 005.xp
C5 ExLU 100.xp
C-6
C6 FuLU 005.xp
C6 FuLU 100.xp
C-7
C7 ExLU 005.xp
C7 ExLU_100.xp
All improvements which fell under the Construction Scenario model were incorporated
into these ten Baseline models. All improvements based on the Under Design model
scenario were incorporated into the resulting ten Construction Scenario models.
6.1 Projects Completed & Under Construction
The City of Miami has constructed or is in the process of constructing a total of 31
stormwater improvement projects within the C-3, C-4, C-5, and C-6 basins. Outside of
these 31 stormwater management projects, there were four stormwater pump stations
throughout the City that were not part of the ongoing capital improvement projects and
were not included in the models developed by DERM.
6-1
January 2011 City of Miami Phase I - Stormwater Management Master Plan
The construction projects to be incorporated into the Construction Scenario models
were categorized into their main drainage components. The primary drainage
components included in these projects were comprised of:
• Gravity drainage systems with outfalls,
G Exfiltration trenches,
• Drainage wells, and
• Stormwater pump stations
The components of these drainage systems were represented in the XP-SWMM models
by either including the location and size of the drainage component or by an equivalent
rainfall extraction representative of the amount of runoff extraction from overland flow as
described previously. The drainage components of each project were applied to the
drainage sub -basin where these main components provide flood protection. The
projects included in the Construction Scenario models, in addition to the sub -basins
where these projects provide a stormwater management benefit to, are listed in detail in
Attachment N.
Two of the projects listed in Attachment N, projects B-50704 and B-30008, were
included in the Construction Scenario models because they were scheduled to begin
construction within a six-month time frame from the date of this SWMMP. As part of the
Construction Scenario models, an approximate total length of 110,000-linear feet (If) of
exfiltration trench and 33 injection drainage wells were included in the models in
addition to an approximate total pump station capacity of 215,000 gallons per minute
(gpm) discharging into the C-4, C-5, and C-6 canals. Additionally, Attachment N
provides a detailed table of the project components included in the Construction
Scenario models and the sub -basins attributed to these components.
The revised models and names used for the Construction Scenario models are as
shown in Table 6-3. These XP-SWMM files contain a "_CS" appended to the digital
model file name to denote this specific model scenario.
Table 6-3 — XP-SWMM Basin Models - Construction Scenario
Basin
Construction' Scenario Models
;, ' 5-year Event
Construction Scenario models
100-year;Event
C-3
C3 ExLU 005 CS.xp
C3_ExLU_100_CS.xp
C-4
C4_FuLU_005_CS.xp
C4_FuLU_100_CS.xp
C-5
C5 ExLU 005 CS.xp
C5 ExLU 100 CS.xp
C-6
C6 FuLU_005_CS.xp
C6_FuLU 100 CS.xp
C-7
C7_ExLU_005_CS.xp
C7_ExLU_100_CS.xp
6.2 Projects Under Design
The City of Miami is in the process of designing four stormwater improvement or flood
protection projects within the C-4, C-6, and C-7 basins in order to improve localized
flood problems. Preliminary design information was provided by the City for these
projects in order to incorporate the main components of these improvements into the
Under Design Scenario models.
January 2011 City of Miami Phase I - Stormwater Management Master Plan
The projects in the Under Design Scenario models were represented in the same
manner as with the projects under construction. In the Under Design model scenario,
an approximate total length of 4,500-If of exfiltration trench and four drainage wells were
included in this scenario's models. The projects included in the Under Design Models
are listed in detail in Attachment N in addition to the sub -basins where these projects
are providing a stormwater management benefit.
The revised models used for the Under Design model scenario are as shown in Table
6-4. TheseXP-SWMM files contain a "_DS" appended to the digital model file name to
denote this specific model scenario.
Table 6-4 — XP-SWMM Basin Models - Under Design Scenario
Basin `
Construction Scenario Models
5-year Event
Construction` Scenario;; models
100-year Event
C-3
C3_ExLU 005 DS xp
C3 ExLU_100 DS.xp
C-4
C4_FuLU_005_DS.xp
C4_FuLU_100_DS.xp
C-5
C5_ExLU_005_DS.xp
C5_ExLU_100_DS.xp
C-6
C6_FuLU 005 DS.xp
C6_FuLU_100_DS.xp
C-7
C7_ExLU_005_DS.xp
C7_ExLU_100_DS.xp
6.3 Hydrologic & Hydraulic Model Setup - Representation of Stormwater
Projects in XP-SWMM
Evaluation of construction as -built and design plans indicated that stormwater
improvement projects completed, under construction, and under design were comprised
of predominantly four stormwater management structural components which included
bigger pipes (outfalls or between sub -basins), exfiltration trenches, gravity injection
wells, and stormwater pump stations.
Because of the planning level nature of this study, these structural components were
represented conceptually in the applicable sub -basin within the XP-SWMM models.
Conveyance systems within a sub -basin were not detailed in the model, and only major
components which transferred or facilitated the transfer of stormwater flows between
sub -basins and/or major components which transferred stormwater flows to the
groundwater or to canals/rivers were represented. The following sub -sections provide a
description of how these stormwater management structural components were
represented in applicable XP-SWMM models.
6.3.1 New or Increased Pipe Size
Various projects replaced small existing pipes with larger pipes with higher capacities
for conveying water from one sub -basin to another or to canal or water body sub basin.
For these types of improvements, major components of stormwater management
systems were incorporated into the model by either changing the size of an existing
conduit size or by incorporating the conduit in the system. Due to the coarse scale of
these models, only conduits representing an inter -basin transfer or stormwater runoff or
transfer of stormwater from a sub -basin to a canal link (outfall) were improved or
represented. Individual components representing transfer of stormwaters within a sub -
basin were ignored.
I
6-3
January 2011 City of Miami Phase I - Stormwater Management Master Plan
6.3.2 Exfiltration Trenches
DERM used the XP-SWMM built-in Horton infiltration function to account for
groundwater infiltration through the use of exfiltration trenches throughout a design
storm event. Areas shown to be contributing to an exfiltration trench system were
designated from a subcatchment within a node using the Green-Ampt infiltration
function to a subcatchment using the Horton infiltration function (Le. if a sub -basin was 6
acres in area and 1 acre was serviced by exfiltration trenches, the Green-Ampt
subcatchment of this sub -basin would be 5 acres in size and the Horton subcatchment
would be 1 acre in size). The various parameters used in both these functions were
adjusted during the calibration and verification phase of the DERM activities to arrive at
the values present in the models used for this SWMMP update.
With regards to representing exfiltration trenches for this study, initially, .a methodology
similar to that used by DERM during their stormwater modeling activities was tested.
Additional areas shown to be serviced by exfiltration trenches were transferred from the
Green-Ampt subcatchment to the Horton subcatchment of a given node. During initial
testing of this methodology, it was noted that stages within the model did not show
representative stage reductions that are typical with extractions of exfiltration trenches.
Various attempts were made to correct this anomaly without success, and due to these
unexpected results, the Green-Ampt-to-Horton methodology was abandoned in lieu of
an extraction methodology.
The extraction methodology used for this SWMMP update assumed that the exfiltration
trenches in a given system have the ability to extract or exfiltrate up to 3.28 inches of
the total rainfall depth produced by a design rainfall event over the area contributing to
the exfiltration trench, which is an accepted practice by DERM and the SFWMD. This
resulting extraction volume was then prorated over the entire sub -basin area and then
extracted from the total rainfall depth associated with a given rainfall condition.
Exfiltration :Trench
Figure 6-1 — Area Attributed to an Exfiltration Trench Length
For this methodology, the total area contributing to an exfiltration trench was based on
the length of exfiltration trench determined for a given sub -basin. This length was
associated to a typical width of 320 ft along the length of the exfiltration trench. The
January 2011 City of Miami Phase I - Stormwater Management Master Plan
width was based on a random sampling of the areas where exfiltration trenches were
implemented, which showed that 160 ft on either side of a trench typically extends to the
rear of a property in a typical residential area within the City - see Figure 6-1.
With the total area serviced by an exfiltration trench determined, the 3.28 inches could
then be prorated over the sub -basin based on the sub -basin's total area. A reduction
factor was also used for all exfiltration trenches based on the age of the system. A
decay of 1% was used per year of age of the system. This reduction was applied to the
total exfiltration trench extraction capacity. Calculation Example 6-5 provides an
example of how the extraction methodology for exfiltration trenches was calculated for a
sample sub -basin within the revised Construction and Under Design models.
Calculation Example 6-5 — Exfiltration Trench Extraction Methodology Example
Project & Sub -basin
Information
Sub -basin Name = C4-S-19
Basin total area = 112.17 acres
Project # = B-5582
Construction Date = 5/1/1991
Area Attributed to
Exfiltration Trench
Exfiltration trench length for project = 7,906 If
Contributing width = 320 ft
Total drainage area = (7,906 If x 320 If) / 43,560 = 58.08 acres
Rainfall Extraction
Depth Determination
Extraction depth per unit area = 3.28"
Prorated extraction depth = (3.28" x 58.08 acres) / 112.17 acres = 1.6983"
Age of Project = 19.1 Years o 0
Reduction % = 19.1 years x 1.0% per year = 19.1 h
Reduced Extraction depth = (1.6983" x (100% - 19.1 %) ) = 1.3739"
5-Year Rainfall
Parameters
Original 5-year sub -basin rainfall multiplier = 7.00
Original 5-year sub -basin rainfall depth = 1.0"
Resulting 5-year sub -basin rainfall depth = 7.0"
Revised 5-Year Rainfall
Parameters
Revised 5-year sub -basin rainfall depth = (7.0" - 1.3739") = 5.63"
Revised 5-year sub -basin rainfall multiplier = (5.63" / 1") = 5.63
100•Year Rainfall
Parameters
Original 100-year sub -basin rainfall multiplier = 13.65
Original 100-year sub -basin rainfall depth = 1.359"
Resulting 100-year sub -basin rainfall depth = 18.5504"
Revised 100-Year
Rainfall Parameters
Revised 100-year sub -basin rainfall depth = (18.5504" - 1.3739") = 17.1765"
Revised 100-year sub -basin rainfall multiplier = (17.1765" / 1.359") = 12.64
In some cases, due to the small amount of exfiltration trench constructed within a
sub -basin, the total extraction often resulted in a negligible decrease in the rainfall
depth. Table 6-6 provides a listing of the total length of exfiltration trench incorporated
into the models under both the Construction and Under Design Scenarios.
Attachment 0 provides a detailed listing of the extractions implemented in the model
and the basin and sub -basins where these extractions resided.
Table 6-6 — Total Length of Exfiltration Trench incorporated into each Model
Basin
Length of Exfiltration Trench (If)
C-3
1,000
C-4
42,400
C-5
26,500
C-6
43,000
C-7
3,000
This total is the combined length in both the Construction and Under Design Scenario
6.3.3 Gravity Injection Wells
Based on discussions with City staff, gravity injection wells used in stormwater
management systems within the City are mainly used to account for water quality
6-5 . _
January 2011 City of Miami Phase I - Stormwater Management Master Plan
volume requirements. As such, the volumetric capacity of these gravity injection wells
was correlated to the current water quality requirements from Miami Dade County
DERM and SFWMD. This stipulation requires that either the first 1 inch of runoff from
the total project area or 2.5 inches of runoff from the total impervious project area be
treated, whichever is greater.
For the purposes of this SWMMP, a similar extraction methodology for exfiltration
trenches was used for handling gravity injection well capacity within the models. The
total volumetric capacity of a well or wells was based on the total project area and the
water quality requirement for that project area. This volume was prorated over the
entire sub -basin resulting in a reduction in the rainfall depth for a given sub -basin. A
reduction factor was also used for all injection wells based on the age of the wells. A
decay of 0.5% was used per year of age of the well. This reduction was applied to the
assumed volumetric capacity of the well and applied as an extraction factor to the
rainfall of the applicable sub -basin. Calculation Example 6-7 provides an example of
how the extraction methodology for wells was calculated for a sample sub -basin within
the revised Construction and Under Design models.
Calculation Example 6-7 - Gravity Injection Well Extraction Methodology Example
Project & Sub -basin
Information
Sub -basin Name = C6-N-19
Project # = B-5586
Construction Date = 1/1/1992
Basin total area = 180.86 acres
Area Attributed to
Drainage Wells
Contributing project area = 4.67 acres
Water Quality Treatment volume for wells = 2.5"
Rainfall Extraction
Depth Determination
Prorated extraction depth = (2.5" x 4.67 acres) / 180.86 acres = 0.0646"
Age of Project = 18.4 Years
Reduction % = 18.4 years x 0.5% per year = 9.2%
Reduced Extraction depth = (0.0646" x (100% - 9.2%)) = 0.0587"
5-Year Rainfall
Parameters
Original 5-year sub -basin rainfall multiplier = 4.9
Original 5-year sub -basin rainfall depth = 1.0"
Resulting 5-year sub -basin rainfall depth = 4.9"
Revised 5-Year Rainfall
Parameters
Revised 5-year sub -basin rainfall depth = (4.9" - 0.0587") = 4.84"
Revised 5-year sub -basin rainfall multiplier = (4.84" / 1") = 4.84
100-Year Rainfall
Parameters
Original 100-year sub -basin rainfall multiplier = 8.2
Original 100-year sub -basin rainfall depth = 1.359"
Resulting 100-year sub -basin rainfall depth = 11.1438"
Revised 100-Year
Rainfall Parameters
Revised 100-year sub -basin rainfall depth = (11.1438" - 0.0587") = 11.0851"
Revised 100-year sub -basin rainfall multiplier = (11.0851" / 1.359") = 8.16
Similar to the extractions for exfiltration trenches, due to the small amount of wells
constructed within a sub -basin, the total extraction often resulted in a negligible
decrease in the rainfall depth. In total, 33 injection wells were incorporated into
sub -basins within the C-6 model only - 29 in the Construction Scenario and 4 in the
Under Design Scenario. Attachment 0 provides a detailed listing of the extractions
implemented in the model and the sub -basins where these extractions resided.
6.3.4 Stormwater Pump Stations
Stormwater pump stations were represented as multi -links within the applicable
XP-SWMM model. Each pump station's operating conditions were either collected from
as -built plans provided by the City or through discussions with the City of Miami staff
responsible with the maintenance and operation of the pump stations within the City.
Nine pump stations in total were incorporated into the XP-SWMM models, all of which
J■t
6-6 " ' '�
January 2011 City of Miami Phase I - Stormwater Management Master Plan
were within the Construction Scenario models. Attachment P provides information
regarding the capacity and operating conditions used for each of the pump stations as
well as location maps for each pump station showing the relative location of inflow
pipes, outfall pipes, and the pump station structure - pipe sizes and pump station
capacities are shown where available. Table 6-8 provides a listing of the pump stations
within the City of Miami which were incorporated into the models and their respective
total peak discharge capacity.
Table 6-8 — Pump Stations within the City of Miami
'Pump Station Name ' :
Attachment CUpstream
Figure Number
Sub -Basin
Total Pump=Station
Capacity (GPM)
Antonio Maceo Park
Figure C-1
C4-S-23
6,732
Flagami PS #1
Figure C-2
C4-S-18
13,400
Flagami PS #2
Figure C-3
26,700
Flagami PS #3
Figure C-4
18.000
Flagami PS #4
Figure C-5
C4-S-17
18,000
*Riverview
Figure C-6
C6-S-16
34,000
`Lawrence
Figure C-7
C6-S-18
40,000
*Orange Bowl
Figure C-8
CC6-S-6
50,000
*SR 836/Douglas Road
Figure C-9
C5-836-D
10,000
'Not included in the project listing in Attachment
6.4 Basin Hydrologic & Hydraulic Model Setup
As previously described, the XP-SWMM models developed as part of the existing and
future condition land uses without City flood protection projects were modified to include
the key structural components of projects completed and under construction. These
models were then used to evaluate the flood protection benefits for these projects.
Once the benefits of these projects were assessed, the XP-SWMM models were further
modified to include the key structural components of the projects under design to
assess the additional benefits that would be realized if these projects were to, be
constructed.
The following sub -sections provide a description of what primary structural drainage
components were incorporated into the XP-SWMM models to assess the flood
protection benefits of stormwater improvements projects completed, under construction
and under design within the C-3, C-4, C-5, C-6 and C-7 basins and in which specific
model scenario they were included in Projects highlighted in yellow under the following
subsections are projects that fell under the Design Scenario. Attachment N provides a
detailed list of the projects implemented, the affected sub -basins, the main structural
components, and the total extractions or model parameters adjusted in the XP-SWMM
models. Attachment D provides a map of the sub -basins having projects implemented.
6.4.1 C-3 Basin
All changes made to the C-3 model's sub -basins consisted of extractions from
exfiltration trenches. Most of the projects incorporated appeared to be to reduce
localized flooding during moderate rainfall events. In total, approximately 1,000 If of
exfiltration trench were incorporated into the C-3 model. Table 6-9 provides a detailed
list of these projects, the affected sub -basins, and the main structural components
incorporated into the C-3 model.
6-7
January 2011
City of Miami Phase I - Stormwater Management Master Plan
Table 6-9 — Main project components incorporated into the C-3 Model's sub -basins
City of Miami
Project Number
DERM
Basin
Sub -basin
Affected
Description of Drainage Improvements
Model Scenario
B-5582
C-3
C3-N1-2
95 LF of 24" Exf. Trench
Construction
B-5638
C-3
C3-N4-2
113 LF of 24" Exf. Trench
Construction
8-5638
C-3
DA1-NE
160 LF of 24" Exf. Trench
Construction
B-5647
C-3
C3-N1-2
100 LF of 24" Exf. Trench
Construction
B-5647
C-3
C3-N4-2
524.6 LF of 24" Exf. Trench
Construction
6.4.2 C-4 Basin
The majority of the changes made to the C-4 model's sub -basins consisted of
extractions from exfiltration trenches. It appeared that the intent of the majority of the
projects implemented were to reduce localized flooding during moderate rainfall events.
However, there were five projects which involved the construction of a significant length
of exfiltration trench, projects B-5582, B-5629, B-50695, B-50703 and B-50704. In total,
approximately 42,400 If of exfiltration trench were incorporated into the C-4 model. In
addition to the exfiltration trench lengths, five pump stations were also incorporated into
the model with a total peak discharge capacity of approximately 83,000 gpm. Four of
these five pump stations, from project B-50696, were included in the future conditions
model for the C-4 although changed in the parameters in the model were required.
Table 6-10 provides a detailed list of the projects, the affected sub -basins, and the main
structural components incorporated into the C-4 model.
Table 6-10 — Main project components incorporated into the C-4 Model's sub -basins
City of Miami
Project Number
DERM
Basin
Sub -basin
Affected
Description of Drainage Improvements
Model Scenario
B-5582
C-4
C4-S-17
150 LF of 24" Exf. Trench
Construction
B-5582
C-4
C4-S-19
7906 LF of 24" Exf. Trench
Construction
B-5582
C-4
C4-S-22
145 LF of 24" Exf. Trench
Construction
B-5586
C-4
CC4-S-22
185 LF of 24" Exf. Trench
Construction
B-5587
C-4
C4-S-13
490 LF of 24" Exf. Trench
Construction
B-5587
C-4
CC4-S-21
319 LF of 24" Exf. Trench
Construction
B-5629
C-4
C4-S-22
40% 12063 LF of 24" Exf. Trench
Construction
B-5629
C-4
C4-S-23
55% 12063 LF of 24" Exf. Trench
Construction
B-5629
C-4
C4-S-24
5%_12063 LF of 24" Exf. Trench
Construction
B-5638
C-4
C4-S-26
104.5 LF of 24" Exf. Trench
Construction
B-5638
C-4
CC4-S-22
213 LF of 24" Exf. Trench
Construction
B-5638
C-4
CC4-S-23
799.5 LF of 24" Exf. Trench
Construction
B-5638
C-4
CC4-S-25
104.5 LF of 24" Exf. Trench
Construction
B-5647
C-4
CC4-S-22
294.4 LF of 24" Exf. Trench
Construction
B-50695
C-4
C4-S-17
690 LF of Exf. Trench
Construction
13-50695
C-4
C4-S-18
3073 LF of Exf. Trench
Construction
B-50695
C-4
C4-S-25
346 LF of Exf. Trench
Construction
8-50696
C 4
C4 S-17
4 Drainage Pump Stations - Discharging to 48"/54"
FM on SW 64 Ave
Construction
B-50696
C 4
C4 S-18
4 Drainage Pump Stations - Discharging to 48"/54"
FM on SW64Ave
Construction
B-50696
C-4
C4 S-25
4 Drainage Pump Stations - Discharging to 48' /54"
FM on SW 64 Ave
Construction
B-50702
C-4
C4-S-23
Pump Station & Outfall Upgrades to Blue Lagoon
Construction
B-50702
C-4
C4-S-24
Pump Station & Outfall Upgrades to Blue Lagoon
Construction
B-50703
C-4
C4-S-22
3441 LF of Exf. Trench
Construction
B-50703
C-4
C4-S-23
1281 LF of Exf. Trench
Construction
B-50704
C-4
C4-S-23
7832 LF of Exf. Trench
Construction
B-50704
C-4
CC4-S-21
995 LF of 24" Exf. Trench
Construction
B-50704
C-4
CC4-S-22
1390 LF of 24" Exf. Trench
Construction
B-50705
C-4
CC4-S-23
820 LF of 24" Exf. Trench
Design
B-50706
C-4
C4-S-18
193 LF of 24" Exf. Trench
Construction
6-8
January 2011 City of Miami Phase I - Stormwater Management Master Plan
6.4.3 C-5 Basin
The majority of the changes made to the C-5 model's sub -basins consisted of
extractions from exfiltration trenches. In the C-5 basin model, the majority of the
projects implemented appeared to consist of abating larger quantities of runoff due to
the large amount of exfiltration trench involved. In total, 26,500-If of exfiltration trench
were incorporated into the C-5 model. In addition to the exfiltration trench lengths, one
FDOT pump station was also incorporated into the model with a total peak discharge
capacity of approximately 10,000 gpm. Table 6-11 provides a detailed list of the
projects, the affected sub -basins, and the main structural components incorporated into
the C-5 model. Table 6-8 provides a listing of the pump station not shown in the project
list which was incorporated into the C-5 model (SR 836/Douglas Road).
Table 6-11 — Main project components incorporated into the C-5 Model's sub -basins
City of Miami
Project Number
BERM
Basin
Sub -basin
Affected
Description of Drainage Improvements
Model Scenario
B-4656
C-5
C6-S-12
2660 LF of 24" Exf. Trench
Construction
B-5577
C-5
C5-S6-1
4527 LF of 24" Exf. Trench
Construction
B-5577
C-5
C5-S6-3
3420 LF of 24" Exf. Trench
Construction
B-5587
C-5
C5-S6-4
5137 LF of 24" Exf. Trench
Construction
B-5638
C-5
C5-S5-3
515.8 LF of 24" Exf. Trench
Construction
B-5638
C-5
C5-S6-4
149.6 LF of 24" Exf. Trench
Construction
B-5641
C-5
C5-S6-4
765 LF of 24" Exf. Trench
Construction
B-5641
C-5
C5-S6-5
1764 LF of 24" Exf. Trench
Construction
B-5647
C-5
C5-S6-4
97.7 LF of 24" Exf. Trench
Construction
B-30629
C-5
C5-S6-4
7441 LF of 24" Exf. Trench
Construction
—
C-5
C5 836-D
FDOT Drainage Pump Station discharging to
Comfort Canal
Construction
6.4.4 C-6 Basin
The changes made to the C-6 model's sub -basins consisted of extractions from
exfiltration trenches and gravity drainage wells, as well as incorporating older
stormwater pump stations which were not initially incorporated into the C-6 model. In
total, 42,400-If of exfiltration trench and 33 gravity drainage wells were incorporated into
the C-6 model. In addition to the exfiltration trench lengths and gravity wells, three
pump stations were also incorporated into the model with a total peak discharge
capacity of approximately 124,000 gpm. Table 6-12 provides a detailed list of the
projects, the affected sub -basins, and the main structural components incorporated into
the C-4 model. Table 6-8 provides a listing of the pump stations not shown in the
project list which were incorporated into the C-6 model.
Table 6-12 — Main project components incorporated into the C-6 Model's sub -basins
City of Miami
Project Number
DERM
Basin
Sub -basin
Affected
Description of Drainage Improvements
Model Scenario
B-4512
C-6
C6-N-19
1164 LF of 30" Exf. Trench
Construction
B-4521A
C-6
C6-N-19
50% of 1118 LF of 30" Exf. Trench
Construction
B-4521B
C-6
C6-N-19
50% of 9 Drainage Welts, 2000 GPM each
Construction
B-4521A
C-6
C6-N-20
50% of 1118 LF of 30" Exf. Trench
Construction
B-4521 B
C-6
C6-N-20
50% of 9 Drainage Wells, 2000 GPM each
Construction
B-4528
C-6
C6-S-18
5031 LF of 30" Exf. Trench
Construction
B-4528
C-6
C6-S-18
1588 LF of 36" Exf. Trench
Construction
B-4528
C-6
C6-S-18
1323 LF of 3' SCT
Construction
B-4554
C-6
CC6-N-11
373 LF of 24" Exf. Trench
Construction
6-9
Oy
January 2011
City of Miami Phase I - Stormwater Management Master Plan
City of Miami
Project Number
DERM
Basin
Sub -basin
Affected
Description of Drainage Improvements
Model Scenario
B-4619
C-6
CC6-N-11
479 LF of 24" Exf. Trench
Construction
B-4620
C-6
C6-N-17
667 LF of 24" Exf. Trench
Construction
B-4620
C-6
CC6-N-13
616.5 LF of 18" Exf. Trench
Construction
B-4633
C-6
CC6-N-11
2088.3 LF of 18" Exf. Trench
Construction
B-4654
C-6
C6-N-17
290 LF of 24" Exf. Trench
Construction
B-4654
C-6
C6-S-13
925 LF of 24" Exf. Trench
Construction
B-4654
C-6
CC6-S-2
491 LF of 24" Exf. Trench
Construction
B-5586
C-6
C6-N-19
40°l0 of 861 LF of 24" Exf. Trench
Construction
B-5586
C-6
C6-N-19
60% of 20 Drainage Wells
Construction
B-5586
C-6
N6-C6-E-2
60% of 861 LF of 24" Exf. Trench
Construction
B-5586
C-6
N6-C6-E-2
60% of 20 Drainage Wells
Construction
B-5595
C-6
CC6-N-14
2121 LF of 36" Exf. Trench
Construction
B-5595
C-6
CC6-N-14
731 LF of 24" Exf. Trench
Construction
B-5608
C-6
C6-S-16
2% of 6975.67 LF of 24" Exf. Trench
Construction
B-5608
C-6
C6-S-16
3% of 6975.67 LF of 24" Exf. Trench
Construction
B-5608
C-6
CC6-S-6
5%of 6975.67 LF of 24" Exf. Trench
Construction
B-5608
C-6
CC6-S-7
90% of 6975.67 LF of 24" Exf. Trench
Construction
B-5611
C-6
CC6-N-14
5504.15 LF of 24" Exf. Trench
Construction
B-5638
C-6
CC6-N-12
300 LF of 24" Exf. Trench
Construction
B-5638
C-6
CC6-N-13
247 LF of 24" Exf. Trench
Construction
B-5647
C-6
C6-S-12
301.8 LF of 24" Exf. Trench
Construction
B-5647
C-6
CC6-S-8
159.5 LF of 24" Exf. Trench
Construction
B-30008
C-6
CC6-S-3
3685 If of 24" Exf. Trench
Construction
B-30008
C-6
CC6-S-4
1495 LF of 24" Exf. Trench
Construction
B-30008
C-6
CC6-S-5
1755 LF of 24" Exf. Trench
Construction
B-30008
C-6
CC6-S-6
100 LF of 24" Exf. Trench
Construction
B-40643A
C 6
C6 N-18
Outfall Upgrades at Seawall - Replace 36" w!
42" & STU
Construction
B-40643A
C-6
C6-N-18
Outfall Upgrades at Seawall - Replace 15" w!
36" & STU
Construction
B-40686
C-6
C6-S-17
728 LF of Exf. Trench
Design
B-40686
C-6
C6-S-17
4 injection wells @ 650 GPM/ft head
Design
B-50643
C-6
CC6-N-17
Dredging - Wagner Creek & Seybold Canal -
Connects Basins
Design
8-50643
C-6
CC6-N-18
Dredging - Wagner Creek & Seybold Canal -
Connects Basins
Design
8-50643
C 6
CC6-N-19
Dredging - Wagner Creek & Seybold Canal -
Connects Basins
Design
B-50683
C-6
CC6-N-12
246 LF of 18" Exf. Trench
Construction
B-50683
C-6
CC6-N-14
1653 LF of 18" Exf. Trench
Construction
6.4.5 C-7 Basin
The only change made to the C-7 model's sub -basins consisted of extractions from one
exfiltration trench project that was under design. In total, 3,000-If of exfiltration trench
was incorporated into the C-7 model. Table 6-13 provides a detailed list of this project,
the affected sub -basin, and the main structural component incorporated into the C-7
model.
Table 6-13 — Main project components incorporated into the C-7 Model's sub -basin
City of Miami
Project Number
DERM
Basin
Sub basin
Affected
Description of Drainage Improvements
Model
Scenario
B-30014
C-7
CC7-S-21
2973 LF of 24" Exf. Trench
Design
6.5 Summary of Results & Rankings - Projects Completed & Under
Construction
The peak stages realized in the Construction Scenario models are shown in Table 6-14.
Sub -basins highlighted in yellow are sub -basins where model parameters were adjusted
6-10
January 2011 City of Miami Phase I - Stormwater Management Master Plan
to account for stormwater management projects which fell under the Construction
Scenario. This table also provides a comparison of the Construction Scenario model
results with those results obtained from the Baseline (Future Land Use) Scenario
models. The model results showed moderate reductions in flood stages for the 5-year
event ranging from negligible reductions to a maximum reduction of 0.86 ft. Reductions
were smaller for the 100-year event where a maximum reduction of 0.27 ft was shown.
Table 6-14 - Stage Comparison - Baseline to Construction Scenarios (NGVD)
Sub -basin
Baseline
Scenario
5-year
Construction
Scenario
5-year
Difference
BIW 5-year
Scenarios
Baseline
Scenario
100-year
Construction
Scenario
100-year
Difference
BIW 100-year
Scenarios
95-5-1
6.64
6.66
0.02
7.16
7.16
0.00
95-S-2
10.61
10.60
-0.01
10.89
10.89
0.00
B4-LeJeu-W
3.67
3.66
0.00
4.75
4.71
-0.03
C3-N1-2
11.71
11.71
0.00
12.52
12.52
0.00
C3-N2-1
8.81
8.81
0.00
10.45
10.45
0.00
C3-N4-1
10.81
10.81
0.00
11.06
11.06
0.00
C3-N4-2
11.93
11.92
-0.01
12.32
12.32
0.00
C3-N-US1-N
8.77
8.77
0.00
10.45
10.45
0.00
C4-C-23
4.46
4.45
-0.02
6.86
6.85
-0.01
C4-C-26
4.28
4.25
-0.02
6.69
6.68
-0.01
C4-S-13
7.43
7.42
0.00
7.82
7.82
0.00
C4-S-14
7.76
7.76
0.00
8.07
8.07
0.00
C4-S-15
8.15
8.15
0.00
8.39
8.39
0.00
C4-S-17
6.30
6.14
-0.16
6.95
6.87
-0.08
C4-S-18
6.69
6.24
-0.45
7.19
7.07
-0.12
C4-S-19
8.04
7.96
-0.09
8.60
8.54
-0.05
C4-S-22
5.43
5.33
-0.10
6.32
6.28
-0.04
C4-S-23
5.52
5.37
-0.15
6.30
6.25
-0.05
C4-S-24
5.53
5.38
-0.14
6.30
6.25
-0.05
C4-S-26
5.17
5.16
0.00
5.48
5.48
0.00
C5-836-A
3.87
3.83
-0.04
4.61
4.61
0.00
C5-836-13
4.11
4.11
0.00
4.38
4.38
0.00
05-836-C
3.98
3.96
-0.01
4.93
4.93
0.01
C5-836-D
4.97
4.71
-0.27
5.45
5.35
-0.10
C5-N2-1
4.34
4.34
0.00
4.74
4.74
0.00
C5-N3-1
4.03
4.04
0.00
4.32
4.33
0.01
C5-S1-1
4.18
4.19
0.01
4.61
4.61
0.00
C5-S1-2
5.37
5.38
0.00
5.69
5.69
0.00
C5-S-37-A
9.55
9.53
-0.02
10.00
10.00
0.00
C5-S-37-B
10.50
10.58
0.08
11.14
11.14
0.00
C5-S-42-A
6.46
6.28
-0.18
8.66
8.49
-0.17
C5-S-42-B
8.64
8.69
0.05
10.44
10.33
-0.11
C5-S5-1
4.68
4.19
-0.49
4.86
4.84
-0.02
C5-S5-2
5.52
5.53
0.01
5.79
5.79
0.00
C5-S5-3
9.81
9.81
0.00
10.21
10.21
0.00
C5-85-4
11.49
11.49
0.00
11.68
11.68
0.00
C5-S6-1
4.79
4.19
-0.60
4.86
4.84
-0.02
C5-S6-3
5.55
5.47
-0.07
5.76
5.74
-0.02
C5-S6-4
7.42
7.27
-0.15
8.66
8.50
-0.16
C5-S6-5
10.61
10.60
-0.01
10.96
10.95
-0.01
C5-S7-1
4.52
4.33
-0.19
5.18
5.09
-0.09
C5-S-7-A
5.29
4.87
-0.42
9.40
9.38
-0.02
C5-S-7-B
5.28
4.60
-0.67
7.92
7.92
0.00
C5-S-FLG-A
9.84
9.74
-0.09
11.58
11.58
0.00
C5-S-FLG-B
9.47
9.43
-0.04
10.93
10.93
-0.01
C5-S-FLG-C
10.18
10.37
0.19
19.55
19.51
-0.04
C6-N-16
5.42
5.44
0.02
6.78
6.77
0.00
C6-N-17
4.69
4.68
-0.01
5.78
5.75
-0.03
C6-N-18
4.50
4.46
-0.04
5.72
5.68
-0.04
C6-N-19
4.18
4.19
0.01
4.45
4.44
-0.01
C6-N-20
4.18
4.17
-0.01
4.33
4.32
-0.01
C6-S-12
4.07
4.04
-0.03
5.11
5.13
0.02
6-11
January 2011
City of Miami Phase 1 - Stormwater Management Master Plan
Sub -basin
Baseline
Scenario
5-year
Construction
Scenario
5-year
Difference
BM 5-year
Scenarios
Baseline
Scenario
100-year
Construction
Scenario
100-year
Difference
BIW 100-year
Scenarios
C6-S-13
3.72
3.71
-0.02
4.62
4.63
0.01
C6-S-14
3.53
3.57
0.04
5.58
5.58
0.01
C6-S-15
4.41
4.20
-0.21
4.87
4.56
-0.30
C6-S-16
4.79
2.35
-2.45
5.82
5.26
-0.56
C6-S-17
3.89
3.88
-0.01
4.29
3.93
-0.36
C6-S-18
4.50
4.13
-0.37
4.62
4.42
-0.20
C6-S-19
4.03
4.01
-0.01
4.03
4.00
-0.02
C7-S-17
5.60
5.60
0.00
6.02
6.02
0.00
CC4-S-20
6.30
6.14
-0.16
6.93
6.85
-0.08
CC4-S-21
8.92
8.91
-0.01
9.39
9.39
-0.01
CC4-S-22
8.92
8.91
-0.01
9.41
9.40
-0.01
CC4-S-23
5.56
5.50
-0.06
6.30
6.26
-0.05
CC4-S-25
4.78
4.75
-0.04
5.40
5.37
-0.03
CC6-N-11
8.80
8.81
0.01
9.75
9.75
0.00
CC6-N-12
5.60
5.58
-0.02
6.80
6.77
-0.03
CC6-N-13
9.14
9.14
-0.01
9.62
9.61
0.00
CC6-N-14
6.88
6.79
-0.09
7.02
6.99
-0.03
CC6-N-15
10.21
10.21
0.01
11.27
11.27
0.00
CC6-N-16
11.27
11.28
0.01
11.61
11.61
0.00
CC6-N-17
4.70
4.70
0.00
5.74
5.70
-0.04
CC6-N-18
4.01
3.87
-0.14
5.72
5.68
-0.04
CC6-N-19
4.53
4.52
-0.01
5.61
5.57
-0.04
CC6-N-20
10.10
10.11
0.01
10.67
10.67
0.00
CC6-S-2
4.64
4.62
-0.02
5.05
5.05
0.00
CC6-S-3
3.93
3.84
-0.09
4.48
4.47
-0.01
CC6-S-4
4.25
4.17
-0.08
4.69
4.63
-0.06
CC6-S-5
6.66
6.63
-0.03
6.86
6.84
-0.02
CC6-S-6
4.79
4.11
-0.68
5.82
5.27
-0.54
CC6-S-7
7.81
7.69
-0.11
9.28
9.21
-0.07
CC6-S-8
8.65
8.67
0.02
10.06
10.07
0.01
CC7-S-21
10.54
10.53
0.00
11.21
11.20
-0.01
CC7-S-22
9.62
9.62
0.00
10.22
10.22
0.00
CC7-S-23
10.69
10.70
0.00
11.02
11.02
0.00
CC7-S-24
10.12
10.10
-0.02
10.81
10.81
0.00
CC7-S-25
10.54
10.53
0.00
11.21
11.20
-0.01
CC7-S-26
9.18
9.23
0.05
11.18
11.18
0.00
DA1-37-A
8.84
8.85
0.02
10.33
10.33
0.00
DA1-37-B
11.88
11.87
-0.01
12.29
12.29
0.00
DA1-37-C
9.60
9.59
0.00
10.65
10.65
0.00
DA1-37-D
10.60
10.68
0.08
14.72
14.70
-0.02
DA1-8-A
10.20
10.19
-0.01
11.83
11.83
0.00
DA1-NE
10.04
10.07
0.03
11.53
11.52
0.00
DA1-SE-1
10.20
10.19
-0.01
11.83
11.83
0.00
DA1-SE-2
9.60
9.59
0.00
10.65
10.65
0.00
N6-C6-E-1
6.63
6.64
0.01
7.69
7.68
-0.01
N6-C6-E-2
6.60
6.62
0.01
7.62
7.59
-0.03
N7-C6-W-1
4.13
4.13
0.00
5.60
5.56
-0.05
The following attachments provide result data from the Completed and Under
Construction model scenario:
• Attachment R - Model Results - Construction Scenario - Tables containing
compiled model results.
• Attachment S - Sub -basin Rankings - Construction Scenario - Tables and
maps showing the resulting sub -basin rankings based.
• Attachment T - Flood Plain Maps - Construction Scenario - Maps showing
the extent of the flood plains based on the available DEM and model results,
6-12
January 2011 City of Miami Phase I - Stormwater Management Master Plan
6.6 Summary of Results and Rankings - Projects Under Design
The peak stages realized in the Under Design Scenario are shown in Table 6-15.
Sub basins highlighted in yellow are sub -basins where model parameters were adjusted
to account for stormwater management projects which fell under the Design Scenario.
This table also provides a comparison of the Under Design Scenario model results with
those results obtained from the Construction Scenario models. The model results
showed minimal reductions in flood stages for the 5-year event ranging from negligible
reductions to a maximum reduction of 0.08 ft. Reductions were greater for the 100-year
event where a maximum reduction of 0.22 ft was shown.
Table 6-15 - Model Results Comparison - Construction to Under Design Scenarios (NGVD)
,Sub -basin
_
Construction;
Scenario '
5-year
, Design
Scenario -
5-year
'Difference .:;'Construction'
BIW 5-year
Scenarios-.
'Scenario' .
.100-year .
',-Design
Scenario
100-year
-Difference .'
BIW 100-year
Scenarios
95-S-1
6.66
6.66
0.00
7.16
7.16
0.00
95-S-2 _ .
10.60
10.60
0.00
10.89
10.89
0.00
B4-LeJeu-W
3.66
3.66
0.00
4.71
4.71
0.00
C3-N1-2
11.71
11.71
0.00
12.52
12.52
0.00
C3-N2-1
8.81
8.81
0.00
10.45
10.45
0.00
C3-N4-1
10.81
10.81
0.00
11.06
11.06
0.00
C3-N4-2
11.92
11.92
0.00
12.32
12.32
0.00
C3-N-US1-N
8.77
8.77
0.00
10.45
10.45
0.00
C4-C-23
4.45
4.45
0.00
6.85
6.85
0.00
C4-C-26
4.25
4.25
0.00
6.68
6.68
0.00
C4-S-13
7.42
7.42
0.00
7.82
7.82
0.00
C4-S-14
7.76
7.76
0.00
8.07
8.07
0.00
C4-S-15
8.15
8.15
0.00
8.39
8.39
0.00
C4-S-17
6.14
6.14
0.00
6.87
6.87
0.00
C4-S-18
6.24
6.24
0.00
7.07
7.07
0.00
C4-S-19
7.96
7.96
0.00
8.54
8.54
0.00
C4-S-22
5.33
5.33
0.00
6.28
6.28
0.00
C4-S-23
5.37
5.37
0.00
6.25
6.25
0.00
C4-S-24
5.38
5.38
0.00
6.25
6.25
0.00
C4-S-26
5.16
5.16
0.00
5.48
5.48
0.00
C5-836-A
3.83
3.83
0.00
4.61
4.61
0.00
C5-836-B
4.11
4.11
0.00
4.38
4.38
0.00
C5-836-C
3.96
3.96
0.00
4.93
4.93
0.00
C5-836-D
4.71
4.71
0.00
5.35
5.35
0.00
C5-N2-1
4.34
4.34
0.00
4.74
4.74
0.00
C5-N3-1
4.04
4.04
0.00
4.33
4.33
0.00
C5-S1-1
4.19
4.19
0.00
4.61
4.61
0.00
C5-S1-2
5.38
5.38
0.00
5.69
5.69
0.00
C5-S-37-A
9.53
9.53
0.00
10.00
10.00
0.00
C5-S-37-B
10.58
10.58
0.00
11.14
11.14
0.00
C5-S-42-A
6.28
6.28
0.00
8.49
8.49
0.00
C5-S-42-B
8.69
8.69
0.00
10.33
10.33
0.00
C5-S5-1
4.19
4.19
0.00
4.84
4.84
0.00
C5-S5-2
5.53
5.53
0.00
5.79
5.79
0.00
C5-S5-3
9.81
9.81
0.00
10.21
10.21
0.00
C5-S5-4
11.49
11.49
0.00
11.68
11.68
0.00
C5-S6-1
4.19
4.19
0.00
4.84
4.84
0.00
C5-S6-3
5.47
5.47
0.00
5.74
5.74
0.00
C5-S6-4
7.27
7.27
0.00
8.50
8.50
0.00
C5-S6-5
10.60
10.60
0.00
10.95
10.95
0.00
C5-S7-1
4.33
4.33
0.00
5.09
5.09
0.00
C5-S-7-A
4.87
4.87
0.00
9.38
9.38
0.00
C5-S-7-B
4.60
4.60
0.00
7.92
7.92
0.00
C5-S-FLG-A
9.74
9.74
0.00
11.58
11.58
0.00
C5-S-FLG-B
9.43
9.43
0.00
10.93
10.93
0.00
C5-S-FLG-C
10.37
10.37
0.00
19.51
19.51
0.00
C6-N-16
5.44
5.44
0.00
6.77
6.77
0.00
6-13
January 2011
City of Miami Phase I - Stormwater Management Master Plan
Sub -basin
Construction
Scenario
5year
Design
Scenario
5-year
Difference
B/W 5-year
Scenarios
Construction
Scenario
100-year
Design
Scenario
100-year
Difference
B/W 100-year
Scenarios
C6-N-17
4.68
4.68
0.00
5.75
5.75
0.00
C6-N-18
4.46
4.46
0.00
5.68
5.68
0.00
C6-N-19
4.19
4.19
0.00
4.44
4.44
0.00
C6-N-20
4.17
4.17
0.00
4.32
4.32
0.00
C6-S-12
4.04
4.04
0.00
5.13
5.13
0.00
C6-S-13
3.71
3.71
0.00
4.63
4.63
0.00
C6-S-14
3.57
3.57
0.00
5.58
5.59
0.01
C6-S-15
4.20
4.20
-0.01
4.56
4.56
0.00
C6-S-16
2.35
2.35
0.00
5.26
5.26
0.00
C6-S-17
3.88
3.86
-0.02
3.93
3.91
-0.02
C6-S-18
4.13
4.13
0.00
4.42
4.42
0.00
C6-S-19
4.01
4.01
0.00
4.00
4.00
0.00
C7-S-17
5.60
5.60
0.00
6.02
6.02
0.00
CC4-S-20
6.14
6.14
0.00
6.85
6.85
0.00
CC4-S-21
8.91
8.91
0.00
9.39
9.39
0.00
CC4-S-22
8.91
8.91
0.00
9.40
9.40
0.00
CC4-S-23
5.50
5.49
-0.01
6.26
6.26
0.00
CC4-S-25
4.75
4.75
0.00
5.37
5.37
0.00
CC6-N-11
8.81
8.81
0.00
9.75
9.75
0.00
CC6-N-12
5.58
5.58
0.00
6.77
6.77
0.00
CC6-N-13
9.14
9.14
0.00
9.61
9.61
0.00
CC6-N-14
6.79
6.79
0.00
6.99
6.99
0.00
CC6-N-15
10.21
10.21
0.00
11.27
11.27
0.00
CC6-N-16
11.28
11.28
0.00
11.61
11.61
0.00
CC6-N-17
4.70
4.70
0.00
5.70
5.70
0.00
CC6-N-18
3.87
3.87
0.00
5.68
5.68
0.00
CC6-N-19
4.52
4.52
0.00
5.57
5.57
0.00
CC6-N-20
10.11
10.11
0.00
10.67
10.67
0.00
CC6-S-2
4.62
4.62
0.00
5.05
5.05
0.00
CC6-S-3
3.84
3.77
-0.07
4.47
4.45
-0.02
CC6-S-4
4.17
3.89
-0.27
4.63
4.56
-0.07
CC6-S-5
6.63
6.63
0.00
6.84
6.84
0.00
CC6-S-6
4.11
4.09
-0.01
5.27
5.27
0.00
CC6-S-7
7.69
7.69
0.00
9.21
9.21
0.00
CC6-S-8
8.67
8.67
0.00
10.07
10.07
0.00
CC7-S-21
10.53
10.53
0.00
11.20
11.20
0.00
CC7-S-22
9.62
9.62
0.00
10.22
10.22
0.00
CC7-S-23
10.70
10.70
0.00
11.02
11.02
0.00
CC7-S-24
10.10
10.10
0.00
10.81
10.81
0.00
CC7-S-25
10.53
10.53
0.00
11.20
11.20
0.00
CC7-S-26
9.23
9.23
0.00
11.18
11.18
0.00
DA1-37-A
8.85
8.85
0.00
10.33
10.33
0.00
DA1-37-B
11.87
11.87
0.00
12.29
12.29
0.00
DA1-37-C
9.59
9.59
0.00
10.65
10.65
0.00
DA1-37-D
11.74
11.74
0.00
12.31
12.31
0.00
DA1-8-A
10.19
10.19
0.00
11.83
11.83
0.00
DA1-NE
10.19
10.19
0.00
11.83
11.83
0.00
DA1-SE-1
10.19
10.19
0.00
11.83
11.83
0.00
DA1-SE-2
9.59
9.59
0.00
10.65
10.65
0.00
N6-C6-E-1
6.64
6.64
0.00
7.68
7.68
0.00
N6-C6-E-2
6.62
6.62
0.00
7.59
7.59
0.00
N7-C6-W-1
4.13
4.13
0.00
5.56
5.56
0.00
The following attachments provide result data from the Under Design model scenario:
• Attachment U - Model Results - Construction Scenario - Tables containing
compiled model results.
• Attachment V - Sub -basin Rankings - Construction Scenario - Tables and
maps showing the resulting sub -basin rankings based.
• Attachment W - Flood Plain Maps - Construction Scenario - Maps showing
the extent of the flood plains based on the available DEM and model results.
6-14
January 2011 City of Miami Phase I - Stormwater Management Master Plan
6.7 Sub -basin Rankings & Comparisons - Construction & Under Design
Scenarios
Table 6-16 provides a summary of the rankings obtained for the Baseline Scenario and
the revised rankings from the Construction and Under Design Scenarios. Sub -basins
highlighted in yellow are sub -basins where model parameters were adjusted to account
for stormwater management projects which fell under the Construction and Design
Scenarios. Additionally a comparison was performed showing the difference between
the Baseline and Construction Scenarios and between the Construction and Under
Design Scenarios.
The ranking results did not show a significant change in rank. This minor change in
ranking may be attributed to the fact that most of the stormwater management systems
incorporated into the models are secondary drainage systems meant to remedy
localized flooding and are not entirely represented in the models. Additionally, these
systems may not be designed for the 100-year event which is the controlling factor in
the basin ranking procedure (100-year event is used to quantify the number of
structures flooded which is the highest ranking factor).
Table 6-16 — Sub -basins Rankings and Comparisons
Sub -basin
Name
Baseline
Rank
Construction Scenario
Under Design Scenario
Rank
Comparison to
Baseline Rank
Rank
Comparison to
Construction Rank
CC6-N-12
1
1
0
1
0
CC7-S-25
2
2
0
2
0
CC7-S-21
3
3
0
3
0
C6-N-17
4
4
0
4
0
CC7-S-24
5
5
0
5
0
C4-S-17
6
6
0
6
0
CC6-N-11
7
7
0
7
0
C6-S-12
8
8
0
8
0
CC4-S-21
9
9
0
9
0
CC7-S-26
10
10
0
10
0
C4-S-18
11
11
-1
12
1
C4-S-18
11
11
-1
12
1
C4-S-23
12
12
1
11
-1
C5-S5-3
13
13
0
13
0
CC6-S-8
14
14
0
14
0
DA1-SE-2
15
15
0
15
0
C4-S-19
16
16
0
16
0
C5-S6-4
17
17
-1
18
1
CC6-N-13
18
18
1
17
-1
C6-N-18
19
19
0
19
0
DA1-NE
20
20
0
20
0
C7-S-17
21
21
0
21
0
C4-S-13
22
22
0
22
0
CC4-S-23
23
23
0
23
0
CC7-S-23
24
24
0
24
0
C3-N4-2
25
25
0
25
0
C4-S-15
26
27
1
26
0
CC6-S-7
27
28
0
28
1
C5-S5-1
28
26
-1
27
-1
C5-S6-3
29
30
0
30
1
C5-S6-1
30
29
0
29
-1
C4-S-24
31
31
0
31
0
C5-S6-5
32
32
0
32
0
CC6-S-6
33
34
0
34
1
C5-N3-1
34
33
0
33
-1
6-15
January 2011
City of Miami Phase I - Stormwater Management Master Plan
Sub basin
Name
Baseline
Rank
Construction Scenario
Under Design Scenario
Rank
Comparison to
Baseline Rank
Rank
Comparison to
Construction Rank
C6-S-16
35
35
0
35
0
N6-C6-E-1
36
36
0
36
0
C6-S-13
37
37
0
37
0
C5-S7-1
38
38
-1
39
1
CC6-N-15
39
39
1
38
-1
C5-S5-2
40
40
0
40
0
C6-S-18
41
41
-1
42
1
C3-N2-1
42
42
1
41
-1
C5-N2-1
43
43
0
43
0
C4-S-22
44
44
0
44
0
C4-C-26
45
45
0
45
0
CC4-S-22
46
46
0
46
0
C6-N-16
47
47
0
47
0
C4-S-14
48
48
0
48
0
C6-S-15
49
49
-4
53
4
N6-C6-E-2
50
50
1
49
-1
C6-S-17
51
51
-3
54
3
CC6-N-20
52
52
2
50
-2
C5-S-FLG-C
53
53
2
51
-2
CC7-S-22
54
54
2
52
-2
CC6-S-1
55
102
0
102
47
CC6-S-2
56
55
0
55
-1
C3-N1-2
57
56
0
56
-1
C5-S1-1
58
57
0
57
-1
CC6-S-5
59
58
0
58
-1
CC4-S-20
60
59
0
59
-1
CC6-S-3
61
60
-1
61
0
C5-836-B
62
61
1
60
-2
C6-S-19
63
62
0
62
-1
DA1-SE-1
64
63
0
63
-1
N7-C6-W-1
65
65
0
65
0
C6-N-19
66
64
0
64
-2
DA1-37-C
67
66
0
66
-1
C4-S-26
68
67
0
67
-1
CC6-S-4
69
68
-4
72
3
B4-54S
70
100
0
100
30
B4-LeJeu-W
71
69
1
68
-3
CC4-S-25
72
70
0
70
-2
DA1-37-B
73
71
2
69
-4
95-S-2
74
73
0
73
-1
C5-S-FLG-A
75
72
1
71
-4
C6-N-20
76
74
0
74
-2
DA1-8-A
77
75
0
75
-2
CC6-N-17
78
77
1
76
-2
C5-836-D
79
76
-1
77
-2
CC6-N-16
80
79
0
79
-1
C5-836-C
81
78
0
78
-3
C5-S-7-B
82
80
0
80
-2
C5-S-FLG-B
83
81
0
81
-2
C4-C-23
84
82
0
82
-2
C5-S5-4
85
83
0
83
-2
C5-S-42-A
86
84
0
84
-2
C6-S-14
87
85
0
85
-2
CC6-N-19
88
86
0
86
-2
C5-S-7-A
89
87
0
87
-2
C5-836-A
90
88
0
88
-2
C5-S-37-A
91
89
0
89
-2
C6-12
92
101
0
101
9
CC6-N-18
93
90
0
90
-3
C5-S1-2
94
91
0
91
-3
C3-N-US1-N
95
92
0
92
-3
DA1-37-D
96
93
0
93
-3
CC6-N-14
97
94
-1
95
-2
C5-S-37-B
98
95
1
94
-4
DA1-37-A
99
97
1
96
-3
6-16
January 2011
City of Miami Phase I - Stormwater Management Master Plan
Sub basin
Name
Baseline
Rank
Construction Scenario
Under Design Scenario
Rank
Comparison to
Baseline Rank
Rank
Comparison to
Construction Rank
C5-S-42-B
100
96
-1
97
-3
C3-N4-1
101
98
0
98
-3
95-S-1
102
99
0
99
-3
6.8 Analysis of Repetitive Loss Properties
Of the 135 repetitive Toss properties within the repetitive loss database, 15 properties
may potentially be removed from the database because the estimated building finished
floor elevations are above the 100-year flood plain. These properties are highlighted in
gray and in yellow in Table 6-17 - the properties highlighted in gray are outside of
FEMA Flood Hazard Zones AH and AE and the ones in yellow are inside Zones AH or
AE. It should be noted that the building finished flood elevations are estimated by
adding 8 inches to the elevation of the nearest crown of road. It should also be noted
that 134 of the 135 properties listed in Table 6-17 were built before 1980 and the
building finished floor elevations may be below the estimated values. It can be
assumed that the removal of these properties from the repetitive loss database may be
exceedingly difficult due to their extremely low finished floor elevations. Attachment X
provides maps showing the repetitive loss properties within the limits of this Phase 1
SWMMP in relation to the FEMA Flood Hazard Zones AH and AE and the flood plains
defined through this SWMMP.
Table 6-17 - Sub -basins with Maximum Number of Repetitive Loss Properties
FOLIO
Year
Built
Sub -basin
Finished
Floor
Elevation
100-Year Peak Stages (City Datum - ft)
Depth of
Flooding
(ft)
Baseline
Construction
Under Design
0131340280061
1966
C6-N-17
1.75
6.04
6.04
6.01
4.26
0131320090270
1971
C4-S-24
2.69
6.56
6.56
6.51
3.82
0131320090290
1971
04-S-24
3.08
6.56
6.56
6.51
3.43
0140010040950
1953
C4-S-17
3.76
7.21
7.21
7.13
3.37
0131320090360
1972
C4-S-24
3.27
6.56
6.56
6.51
3.24
0131320090340
1970
C4-S-24
3.31
6.56
6.56
6.51
3.20
0140010040130
1953
C4-S-17
3.95
7.21
7.21
7.13
3.18
0140010040140
1953
C4-S-17
4.14
7.21
7.21
7.13
2.99
0141060183820
1953
C4-S-23
3.69
6.56
6.56
6.51
2.82
0141060183650
1956
C4-S-23
3.71
6.56
6.56
6.51
2.80
0141060690110
1956
C4-S-23
3.71
6.56
6.56
6.51
2.80
0140010041220
1955
C4-S-17
4.33
7.21
7.21
7.13
2.80
0131310180001
-
C4-S-24
3.76
6.56
6.56
6.51
2.75
0131310180001
-
C4-S-24
3.76
6.56
6.56
6.51
2.75
0131310180001
-
C4-S-24
3.76
6.56
6.56
6.51
2.75
0131310182660
1974
C4-S-24
3.76
6.56
6.56
6.51
2.75
0140010031560
1925
C4-S-17
4.39
7.21
7.21
7.13
2.74
0141060183640
1953
C4-S-23
3.84
6.56
6.56
6.51
2.67
0131270230381
1939
CC6-N-12
4.45
7.06
7.06
7.03
2.58
0140010040030
1958
C4-S-17
4.58
7.21
7.21
7.13
2.55
0131270230383
1978
CC6-N-12
4.50
7.06
7.06
7.03
2.53
0131270100221
1956
CC6-N-12
4.71
7.06
7.06
7.03
2.32
0141061080010
1976
C4-S-23
4.27
6.56
6.56
6.51
2.24
0141061080010
1976
C4-S-23
4.27
6.56
6.56
6.51
2.24
0131270100220
1946
CC6-N-12
4.84
7.06
7.06
7.03
2.19
0131270230380
1969
CC6-N-12
4.84
7.06
7.06
7.03
2.19
0140010043140
1953
C4-S-17
4.97
7.21
7.21
7.13
2.16
0131270080030
1956
CC6-N-12
4.89
7.06
7.06
7.03
2.14
0131270080031
1956
CC6-N-12
4.90
7.06
7.06
7.03
2.13
0131270230400
1964
CC6-N-12
4.93
7.06
7.06
7.03
2.10
0141061140001
--
C4-S-23
4.42
6.56
6,56
6.51
2.09
6-17
January 2011
City of Miami Phase I - Stormwater Management Master Plan
FOLIO
Year
Built
' . Sub -basin
-
Finished ':'
Floor
-
Elevation
100;Year Peak
Stages (CityDatum
"'• .
Construction '
- ft)
r
Under Design
Depth of •
Flooding
(ft) ..
' Baseline
0132180130023
1956
CC7-S-24
8.98
11.07
11.07
11.07
2.09
0141061090001
-
C4-S-23
4.44
6.56
6.56
6.51
2.07
0141061100001
-
C4-S-23
4.44
6.56
6.56
6.51
2.07
0141061100020
1975
C4-S-23
4.44
6.56
6.56
6.51
2.07
0131340300040
1971
C6-N-17
3.95
6.04
6.04
6.01
2.06
0141061130010
1972
C4-S-23
4.53
6.56
6.56
6.51
1.98
0141061130020
1972
C4-S-23
4.53
6.56
6.56
6.51
1.98
0131270100350
1949
CC6-N-12
5.05
7.06
7.06
7.03
1.98
0131270140140
1947
CC6-N-12
5.08
7.06
7.06
7.03
1.95
0131270100120
1938
CC6-N-12
5.10
7.06
7.06
7.03
1.93
0141061170020
1972
C4-S-23
4.62
6.56
6.56
6.51
1.89
0141061160020
1973
C4-S-23
4.64
6.56
6.56
6.51
1.87
0131270230290
1963
CC6-N-12
5.16
7.06
7.06
7.03
1.87
0131270230280
1953
CC6-N-12
5.17
7.06
7.06
7.03
1.86
0131270230370
1956
CC6-N-12
5.19
7.06
7.06
7.03
1.84
0131310170001
-
C4-S-24
4.72
6.56
6.56
6.51
1.79
, 0141061210001
--
C4-S-23
4.75
6.56
6.56
6.51
1.76
0131330130760
1945
C6-S-12
3.61
5.37
5.37
5.39
1.76
0131270230080
1965
CC6-N-12
5.27
7.06
7.06
7.03
1.76
0141060183960
1967
04-S-23
4.80
6.56
6.56
6.51
1.71
0131330280211
1968
C5-836-B
2.93
4.63
4.64
4.64
1.70
0140010056600
1949
C4-S-18
5.65
7.45
7.45
7.33
1.68
0131330130740
1945
C6-S-12
3.78
5.37
5.37
5.39
1.59
0131330220630
1957
C5-N2-1
3.40
4.99
5.00
5.00
1.59
0131330680040
1976
C5-S5-1
3.51
5.09
5.12
5.10
1.58
0140010056400
1950
C4-S-18
5.78
7.45
7.45
7.33
1.55
0140010056410
1950
C4-S-18
5.78
7.45
7.45
7.33
1.55
0141050030160
1947
CC4-S-23
4.97
6.56
6.56
6.52
1.55
0131270280210
1970
CC6-N-12
5.54
7.06
7.06
7.03
1.49
0131320050500
1955
C5-S6-1
3.63
5.09
5.12
5.10
1.46
0131270230360
1953
CC6-N-12
5.61
7.06
7.06
7.03
1.42
0131330131950
1956
C5-N3-1
3.16
4.55
4.58
4.59
1.39
0140010043350
1952
C4-S-18
5.95
7.45
7.45
7.33
1.38
0140010055540
1949
C4-S-18
5.95
7.45
7.45
7.33
1.38
0140010056780
1950
C4-S-18
5.97
7.45
7.45
7.33
1.36
0131330220650
1969
C5-N2-1
3.63
4.99
5.00
5.00
1.36
0131330130720
1945
C6-S-12
4.10
5.37
5.37
5.39
1.27
0131330680120
1976
C5-S5-1
3.85
5.09
5.12
5.10
1.24
0131330131910
1936
C5-N3-1
3.33
4.55
4.58
4.59
1.22
0131330040090
1947
DA1-SE-2
9.72
10.91
10.91
10.91
1.19
0131330131911
1926
C5-N3-1
3.41
4.55
4.58
4.59
1.14
0140010043180
1958
C4-S-17
6.02
7.21
7.21
7.13
1.11
0131330131890
1949
C5-N3-1
3.48
4.55
4.58
4.59
1.07
0131340030090
1950
C6-S-13
3.82
4.88
4.88
4.90
1.06
0131320040410
1947
DA1-37-C
9.86
10.91
10.91
10.91
1.05
0131320090380
1960
C5-S7-1
4.32
5.41
5.44
5.35
1.03
0140010030170
1956
C4-5-19
7.77
8.86
8.86
8.80
1.03
0131330133790
1949
C6-S-12
4.36
5.37
5.37
5.39
1.01
0131330131940
1956
C5-N3-1
3.63
4.55
4.58
4.59
0.92
0131270100400
1939
CC6-N-12
6.13
7.06
7.06
7.03
0.90
0141020052690
1957
C6-S-16
4.97
6.08
6.08
5.86
0.89
0131330040340
1947
C5-S5-1
4.21
5.09
5.12
5.10
0.88
0131320090390
1970
C5-S7-1
4.50
5.41
5.44
5.35
0.85
0131330040350
1947
C5-S5-1
4.24
5.09
5.12
5.10
0.85
0131330145000
1950
DA1-SE-2
10.07
10.91
10.91
10.91
0.84
0140010130820
1950
C4-S-18
6.49
7.45
7.45
7.33
0.84
0131320040620
1947
C5-56-1
4.27
5.09
5.12
5.10
0.82
0131330130082
1959
DA1-SE-2
10.10
10.91
10.91
10.91
0.81
0131320090400
1970
C5-S7-1
4.56
5.41
5.44
5.35
0.79
0131330680090
1976
C5-S5-1
4.36
5.09
5.12
5.10
0.73
0131330680080
1976
C5-S5-1
4.43
5.09
5.12
5.10
0.66
0131270270770
1995
CC6-N-12
6.38
7.06
7.06
7.03
0.65
0140010030820
1955
C4-S-19
8.20
8.86
8.86
8.80
0.60
0131330041040
1947
C5-S5-2
5.47
6.07
6.05
6.05
0.58
0131330130050
1954
DA1-SE-2
10.35
10.91
10.91
10.91
0.56
IK
6-18
January 2011
City of Miami Phase I - Stormwater Management Master Plan
FOLIO
Year
Built
Sub basin
Finished
Floor
Elevation
100-Year Peak Stages (City Datum - ft)
Depth of
Flooding
(ft)
Baseline
Construction
Under Design
0131330130060
1950
DA 1-S E-2
10.36
10.91
10.91
10.91
0.55
0131110354110
1954
CC7-S-21
10.96
11.47
11.47
11.46
0.50
0140010041450
1949
C4-S-19
8.31
8.86
8.86
8.80
0.49
0140010041820
1952
C4-S-19
8.32
8.86
8.86
8.80
0.48
0140010120270
1950
C4-S-18
6.86
7.45
7.45
7.33
0.47
0140010041810
1952
04-S-19
8.35
8.86
8.86
8.80
0.45
0131320050160
1954
C5-S6-1
4.65
5.09
5.12
5.10
0.44
0141060183231
1926
C4-S-23
6.08
6.56
6.56
6.51
0.43
0140010030080
1953
C4-S-19
8.39
8.86
8.86
8.80
0.41
0140010130840
1950
C4-S-18
6.92
7.45
7.45
7.33
0.41
0131330040380
1947
C5-S5-1
4.68
5.09
5.12
5.10
0.41
0140010030220
1955
C4-S-19
8.40
8.86
8.86
8.80
0.40
0140010030070
1953
C4-S-19
8.42
8.86
8.86
8.80
0.38
0140010041150
1953
C4-S-19
8.43
8.86
8.86
8.80
0.37
0131330040310
1947
DA 1-S E-2
10.60
10.91
10.91
10.91
0.31
0131330020030
1968
DA1-SE-2
10.61
10.91
10.91
10.91
0.30
0131330610020
1949
C5-N2-1
4.69
4.99
5.00
5.00
0.30
0131330040060
1947
DA1-SE-2
10.62
10.91
10.91
10.91
0.29
0131330020020
1965
DA1-SE-2
10.68
10.91
10.91
10.91
0.23
0131320050170
1954
C5-S6-1
4.91
5.09
5.12
5.10
0.18
0131330040440
1947
DA1-SE-2
10.74
10.91
10.91
10.91
0.17
0131330132740
1955
DA1-SE-2
10.75
10.91
10.91
10.91
0.16
0131330310130
1978
DA1-SE-2
10.81
10.91
10.91
10.91
0.10
0140010041110
1955
C4-S-19
8.72
8.86
8.86
8.80
0.08
0140010056630
1930
C4-S-18
7.61
7.45
7.45
7.33
-
0131270190010
-
CC6-N-12
7.33
7.06
7.06
7.03
-
0131270140080
1929
CC6-N-12
7.35
7.06
7.06
7.03
-
0131350150181
1930
C6-S-15
5.41
5.13
5.13
4.97
-
0140010041140
1953
C4-S-19
9.26
8.86
8.86
8.80
-
0140010031090
1949
C4-S-19
9.34
8.86
8.86
8.80
-
0131330131580
1949
C5-N3-1
5.33
4.55
4.58
4.59
-
0140010041060
1956
C4-S-19
9.63
8.86
8.86
8.80
-
0141050081710
1947
C5-S6-5
12.35
11.21
11.22
11.21
-
0140010041360
1979
C4-S-18
8.78
7.45
7.45
7.33
-
0141020056350
1952
CC6-S-7
11.23
9.54
9.54
9.47
0132300230330
1973
CC6-N-16
14.53
11.87
11.87
11.87
-
0141020051350
1972
C6-S-18
8.30
4.88
4.88
4.68
-
0101110801140
1979
C6-N-20
9.91
4.59
4.59
4.58
-
0131350271030
1940
C6-S-18
14.80
4.88
4.88
4.68
-
Of the 135 repetitive Toss properties which are within the limits of this phase of the
SWMMP update, 98 of those properties are within sub -basins where flood protection
projects have been constructed. Of the remaining 37 repetitive Toss properties, 27 are
within three sub -basins. These sub -basins are listed in Table 6-18. Table 6-18 also
quantifies the number of repetitive loss properties which are within or were directly
adjacent to the 100-year flood plain.
Table 6-18 - Sub -basins with Maximum Number of Repetitive Loss Properties
Sub -basin
Number of Repetitive Loss
Properties within Sub -basin
Number of Properties which are within
the 12" or more 100-year flood plain for
the Construction Scenario
DA1-SE-2
12
11
C5-S5-1
8
8
C5-N3-1
6
5
6-19
January 2011 City of Miami Phase I - Stormwater Management Master Plan
Figure 6-2 shows the sub -basin with no projects implemented and the most repetitive
Toss properties. The repetitive loss properties are shown as black dots and the
12-inches or deeper flood plain is in red, as with all flood plain maps prepared for this
SWMMP update. In order to account for discrepancies within the DEM, properties
which fell within cells which were directly adjacent to 12-inches or deeper flood plain
cells were included in the count provided in Table 6-18.
Figure 6-2— Repetitive Loss Properties within the DA1-SE-2 Basin
6.9 FEMA FIRM Flood Zone Comparisons
A comparison was performed using the 100-year flood plains resulting from the
Construction Scenario model runs - see Attachment Y. In most locations, the identified
flood plains did correlate well with those from the FEMA Flood Zone shapefile collected
from Miami -Dade County. In Figure 6-3 and Figure 6-4, it can be seen how the
resulting flood plains, in green, yellow, and red, follow the approximate boundary of the
FEMA Flood Zones for zones AH and AE.
6-20
January 2011 City of Miami Phase I - Stormwater Management Master Plan
FEMA High Risk Flood Zones
Construction Scenario -100-Year Flood Plain
More Man 12'
_j Between 6' and 12'
•Less than 6'
Figure 6-3 —FEMA Flood Zone AH and AE comparison 1
FEMA Hign Risk Flood Zones
onstrucHon Scenario -100-Year Flood Plain
I More than 12'
Between B' and 12'
Less than6'
Figure 6-4 — FEMA Flood Zone AH and AE comparison 2
6-21
January 2011 City of Miami Phase I - Stormwater Management Master Plan
In some locations, the resulting flood plains from this study go beyond the FEMA Flood
Zones for zones AH and AE - see Figure 6-5. In general, the resulting flood plains from
this SWMMP show flood plain boundaries that either correlate well with the FEMA Flood
Zones for zones AH and AE or exceed beyond those flood plains. Attachment X
contains maps showing the limits of FEMA Flood Zones for zones AH and AE and the
limits of this SWMMP's flood plain limits for the Construction Scenario 100-Year storm
event.
FEMA High Risk Flood Zones
Construction Scenario -100-Year Flood Plain
More than 12'
Between 6' and IT
Less than 6'
Figure 6-5 — FEMA Flood Zone AH and AE comparison 3
The comparison of the FEMA Flood Zones AH and AE to the Under Design flood plains
in not necessary due to the small change in flood extent throughout the Phase I limits.
This results in findings that are the same as those observed under the Construction
Scenario comparisons.
6.10 Conclusion of Modeling with City Flood Protection Projects
Incorporation of the project data provided by the City into the converted DERM models
required a different approach than that which was used during the initial development of
the DERM models. Various unsuccessful attempts were made to implement project
information using the Green-Ampt-to-Horton methodology which resulted in abandoning
this method in lieu of an extraction methodology. The extraction methodology for
exfiltration trenches used for this SWMMP update assumed that the exfiltration trenches
in a given system have the ability to account for up to 3.28" of the total rainfall depth
produced by a rainfall event over the area contributing to the exfiltration trench.
Similarly, the total extraction attributed to a drainage well was based on the total project
area and the water quality requirement for that project area (either the first 1" of runoff
January 2011 City of Miami Phase I - Stormwater Management Master Plan
from the total project area or 2.5" of runoff from the total impervious project area). Also,
pump station parameters and operating conditions were either collected from the as -
built plans provided by the City or through discussions with the City of Miami staff
responsible with the maintenance and operation of the pump stations within the City.
Pump capacities and operating conditions were then directly incorporated into the
models.
The model results obtained from the Construction Scenario showed moderate
reductions in flood stages for the 5-year event ranging from negligible reductions to a
maximum reduction of 0.86 ft. Reductions were smaller for the 100-year event where a
maximum reduction of 0.27 ft was shown. The model results obtained from the Under
Design Scenario showed minimal reductions in flood stages for the 5-year event ranging
from negligible reductions to a maximum reduction of 0.08 ft. Reductions were greater
for the 100-year event where a maximum reduction of 0.22 ft was shown.
The ranking results did not show a significant change in rank. The minor changes in
ranking may be attributed to the fact that most of the stormwater management systems
incorporated into the models are secondary drainage systems meant to remedy
localized flooding and are not entirely represented in the models. Additionally, these
systems may not be designed for the 100-year event which is the controlling factor in
the basin ranking procedure (100-year event is used to quantify the number of
structures flooded which is the highest ranking factor).
The resulting flood plains for the Construction Scenario 100-Year storm event correlated
in large part with the FEMA Flood Zones for zones AH and AE. In some areas it was
noted that the flood plains from this study did exceed beyond the limits of the FEMA
flood zones. Additionally, because the resulting flood plains for the Constructed and
Under Design Scenarios were so similar, comparison of the FEMA Flood Zones AH and
AE to the Under Design Flood Plains was not necessary and resulted in findings that
are the same as those observed under the Construction Scenario comparisons.
Additionally, the analysis of the repetitive loss properties suggests that the removal of
the properties from the repetitive loss database may be exceedingly difficult due to the
extremely low finished floor elevations of these properties and the typical 5-year design
capacity of most projects within the City's stormwater capital improvement plan. It was
notedthat of the 135 repetitive loss properties within the repetitive loss database, that
only 15 properties were above the 100-year flood plain. It is recommended that the City
survey the finished floor elevation of these 15 properties to verify correlation with this
studies estimated finished floor elevations. Of these 15 properties, 6 are within FEMA
Flood Zones AH or AE.
The results obtained from these activities suggest that minor improvements in peak
stages were accomplished. In order to achieve larger reductions in peak stages,
systems with the capability of significantly improving the discharge capability of a
system from a sub -basin or significantly increasing the storage capacity within the basin
would be required and would be dependent on the sub -basin size, location, extent of
existing infrastructure, and available CIP budget.
January 2011
City of Miami Phase I - Stormwater Management Master Plan
7.1 Stormwater Control Measure Criteria Descriptions
Stormwater management systems must adhere to strict water quality and quantity
criteria set forth by various local, state, and federal agencies with jurisdiction within the
state of Florida. All new or improved stormwater management systems must be shown
to adhere to these criteria prior to permitting and be constructed as permitted. As such,
each project which is developed based on the recommendations within this SWMMP
will require full coordination with regulatory agencies and adherence to all local, state,
and federal laws.
7.1.1 Water Quality Regulatory & Permitting Requirements
In the City of Miami, and dependent upon project/site specific circumstances, the South
Florida Water Management District (SFWMD), Miami Dade County Department of
Environmental Resources Management (DERM), and Florida Department of
Environmental Protection (FDEP) may have jurisdiction over stormwater quality criteria.
The following subsections outline the current requirements set forth by these entities.
All systems to be permitted must be designed to meet the most stringent of these
requirements and are specific to each project.
7.1.1.1 ' `iami-Dade County DERM
Miami -Dade County DERM requires that all projects meet the State of Florida water
quality standards as set forth in Florida Administrative Code (F.A.C.) Chapter 17-302.
To assure that this criterion is met, 100 percent of the first one inch of runoff from the
furthest hydrologic point must be retained on site. The methodology for calculating this
volume is outlined in DERM's Policy for Design of Drainage Structures, dated
December 1980 using the following equations, Equations 2.1-1 through 2.1-4.
V = 60CiATt Equation 7.1-1
Where V = Required stormwater quality volume, cubic feet
C = Runoff Coefficient; 0.3 for pervious areas, 0.9 for impervious areas,
or weighted average for areas with mixed type.
A = Total tributary area, acre
Tt = Time to generate one inch of runoff plus the time of concentration,
minutes, from Equation 2.1-2
i = Rainfall intensity, inches per hour, from Equation 2.1-4
Tt = Tc Equation 7.1-2
Where Tc = Time of concentration, minutes
Tr. = Time to generate one inch of runoff, minutes, from Equation 2.1-3
7-1
January 2011 City of Miami Phase I - Stormwater Management Master Plan
=
2940 F-01 Equation 7.1-3
308.5 C - 60.5(0.5895 + F-D 67)
Where F = Storm frequency, years
i = 308.5 Equation 7.1-4
48.6F° 1 + T1(0.5895 + F-° 67)
Additionally, DERM requires that the required stormwater quality volume V from
Equation 2.1-1 is infiltrated into the groundwater table in a period of Tess than 24 hours
and the use of bleeder mechanisms is not allowed.
7.1.1.2 South Florida Water Management District - _ The SFWMD requires that all projects meet State of Florida water quality standards, as
set forth in Florida Administrative Code (F.A.C.) Chapter 17-302. To assure that these
criteria are met, projects must meet the following volumetric retention/detention
requirements, as described in the SFWMD Permit Volume IV:
1. For wet detention systems:
a. A wet detention system is a system where the control elevation is less
than one foot above the seasonal high ground water elevation and does
not bleed -down more than one-half inch of detention volume in 24 hours.
b. The greater of the following volumes must be detained on site:
i. the first one inch of runoff times the total project area
ii. 2.5 inches of total runoff from the impervious area
2. Dry detention systems must provide 75 percent of the required wet detention
volume. Dry detention systems maintain the control elevation at least one foot
above the seasonal high ground water elevation.
3. Retention systems must provide at least 50 percent of the wet detention volume.
4. For projects with impervious areas accounting for more than 50 percent of the
total project area, discharge to receiving water bodies must be made through
baffles, skimmers, and/or other mechanisms suitable of preventing oil and grease
from discharging to or from the retention/detention areas.
Although a determination for detention systems is described within the SFWMD criteria,
Miami -Dade County DERM does not allow for the use of detention systems, either wet
or dry, for the purposes of water quality. Exfiltration trenches with the perforated pipe
located at or above the seasonal high groundwater elevation are considered dry
retention system. Since dry retention ponds and exfiltration trenches are both deemed
to be retention systems, the retention reduction credit outlined under item #3 applies to
all systems within the City of Miami.
7-2
January 2011 City of Miami Phase I - Stormwater Management Master Plan
7.1.1.3 Florida Department of Environmental Protection
The Florida Department of Environmental Protection (FDEP) is in the process of
developing a new stormwater quality rule which will ultimately govern all stormwater
management systems constructed within the state of Florida which discharge to surface
waters. These new standards will be designed to limit nitrogen and phosphorous
discharges into State waterways to prevent algal growth and to satisfy the U.S.
Environmental Protection Agency's (EPA) requirements for pollutant loading of
discharged waters. This new rule is applicable to all rivers, lakes, canals, and retention
ponds within the state of Florida. All projects to be permitted after the implementation of
this new rule will be required to meet the standards set forth by the FDEP.
Initial indications of the new stormwater quality rule appear to set forth criteria
requirements that exceed those currently being imposed by the SFWMD and DERM
within the state of Florida. Due to the currently evolving nature of the new FDEP rule
and because the new rule has not been officially implemented in any form, the details of
this rule have not been captured within this document.
7.1.2 Water Quantity Regulatory and Permitting Requirements
The following subsections outline the most stringent stormwater quantity requirements
applicable to any new City of Miami project. Also, dependent on project specific
circumstances, the City of Miami, SFWMD, Miami -Dade County DERM, FDOT, and
FDEP may have jurisdiction over specific stormwater quantity criteria.
7.1.2.1 City of Miami
The City of Miami has a specific set of design criteria which are used to define the
required level of service provided by a stormwater management system. This criteria is
detailed as follows:
o For landlocked basins and systems with or without emergency overflows:
a. The rational method is used using a 5 year storm up to a 24 hour duration
(volumetric design) with infiltration. The system should not pond overthe
lowest inlet elevation.
b. A flood routing method is used using a 5 year 1 hour storm (FDOT 1 hour
distribution) with infiltration. The system should not pond over the lowest
inlet elevation.
c. A flood routing method is used using a 10 year 24 hour storm (SFWMD 24
hour distribution) with infiltration. The system is allowed to pond up to the
crown of the road.
o For landlocked basins and systems drained by pump stations:
a. A flood routing method is used using a 10 year 24 hour storm (SFWMD 24
hour distribution) within infiltration. The system is allowed to pond up to
the crown of the road.
7-3
January 2011 City of Miami Phase I - Stormwater Management Master Plan
b. A flood routing method is used using a 25 year 24 hour storm (SFWMD 24
hour distribution) no infiltration. The system is allowed to pond up to the
finished floor elevation.
• For systems affecting finished floor elevations
a. 25-year, 3-day for systems with outfalls
b. 100-year, 3-day for systems implementing pump stations or landlocked
systems
Additionally, drainage tributary areas should include the streets and 20 feet frontages of
private properties on either side.
7.1.2.2 Miami -Dade County DERM
For projects that discharge to Miami -Dade County canals, the specific allowable
discharge criteria for that canal must be met. Designers must coordinate with
Miami -Dade County DERM to obtain the applicable discharge criteria of the specific
receiving Miami -Dade County canal or water body.
7.1.2.3 South Florida Water Management District
The SFWMD requires that off -site discharge rates be limited to rates not causing
adverse impacts to existing off -site properties, and:
1. historic discharge rates,
2. rates determined in previous SFWMD permit action, or
3. basin allowable discharge rates.
For projects discharging to a SFWMD canal basin, the SFWMD Permit Volume IV
outlines basin allowable discharge rates. The following SFWMD basins are located
within the City of Miami:
• C-3 (Coral Gables Canal) Basin
• C-4 (Tamiami Canal) Basin
• C-5 (Comfort Canal) Basin
• C-6 (Miami Canal) Basin
• C-7 (Little River canal) Basin
• North Biscayne Bay Basin (coastal basin)
• South Biscayne Bay Basin (coastal basin)
Table 7-1 includes the allowable discharge criteria as per SFWMD requirements.
For project areas where there is no historical discharge rate and that discharge to a
basin which has an unlimited discharge rate or that discharge to tidal waters, the
SFWMD requires that pre -development flows during a 25-year, 72-hour rainfall event
are not increased during post -development conditions.
If a project is in a basin in which the allowable discharge rate is essentially unlimited
7-4
January 2011
City of Miami Phase I - Stormwater Management Master Plan
(i.e. C-4, C-6, and C-7), SFWMD requires that the post -development peak discharge
rate from these projects be maintained at or below the pre -development peak discharge
rate for a 25-year, 3-day design storm event.
Table 7-1 — SFWMD Allowable Discharge Rate Formulas for Basins with Restricted Discharge
Canal;;
Allowable Discharge Rate Formula
Design. ;.
Frequency
C-4
Essentially unlimited inflow by gravity connections east of S.W.
87th Avenue
200 year +
C-6
Essentially unlimited inflow by gravity connection east of FEC
Railroad
200 year +
C-7
Essentially unlimited inflow by gravity connection
100 year +
Where A = drainage area in square miles
Q = allowable runoff in cfs
CSM = cfs per square mile
7.1.2.4 Florida Department of Transportation
FDOT requires that proposed drainage systems meet the offsite discharge requirements
outlined in F.A.C. Chapter 14-86. The following items are of applicable regarding the
FDOT criteria for the transfer of stormwater to the FDOT right of way as a result of
manmade changes to adjacent properties:
o The offsite discharge criteria is based on a critical storm frequency analysis
including storm events with 2- to 100-year frequencies and 1-hour to 10-day
durations for closed basins and 3-day durations for basins with positive outlets.
O Any discharging pipe establishing or constituting a drainage connection to the
FDOT's right of way is limited in size based on the pre -improvement discharge
rate, downstream conveyance limitations, downstream tailwater influences, and
design capacity restrictions imposed by other governmental entities.
O The peak discharge rates and total volumes allowed by applicable local
regulations are not exceeded.
O The improvements shall not increase stormwater discharge rates above the pre -
development conditions.
e The quality of water conveyed by the connection meets all applicable water
quality standards.
7.1.2.5 Florida Department of Environmental Protection
FDEP regulates the construction and operation of injection drainage wells within the
state of Florida. The rules governing the use of injection wells are set forth in F.A.C.
Chapter 62-528 and under this rule, Injection wells for the purposes of stormwater
management are classified as Class V wells. These wells may only discharge into a
geological formation which contains water with more than 10,000 mg/L of dissolved
solids. For this requirement, an assessment of the injection well depth and horizontal
location must be adequately defined where the total dissolved solids exceed this limit.
7-5
January 2011 City of Miami Phase I - Stormwater Management Master Plan
Additionally, the Southeast District of FDEP requires that the stage at an injection well
may not exceed an elevation greater than 8.0 ft-NGVD when associated with a pump
station. This restriction is to prevent vertical migration of injected water along the well
casing.
7.1.2.6 Maximum Allowable Water Elevations
In Miami -Dade County, the DHW elevation is typically defined as the average October
groundwater elevation. These elevations are published in the Miami -Dade County
Public Works Department Design Standards and are used to establish the average high
groundwater elevation typically encountered during the year for the purposes of design.
The maximum allowable water elevations of a project are determined based on an
applicable design storm event of a defined frequency and duration. The City of Miami
requires that all drainage systems be designed for a minimum 5-year frequency design
storm event. Typically, the 1-, 8-, and 24-hour durations are evaluated, with the most
critical duration controlling the design. For drainage systems implementing a pump
station, the 10-year, 24-hour storm event must be evaluated.
The SFWMD and Miami -Dade County DERM also require flood protection of habitable
buildings. The peak 100-year frequency design storm event of critical duration (1- , 8-
and 24-hour) must not exceed adjacent habitable building finished floor elevations.
These entities also require that provisions are made to replace or otherwise mitigate the
loss of historical basin storage impacted by a project.
7.2 Stormwater Management Systems
The following subsections summarize the most common and feasible stormwater
control measures available to the City of Miami for the purposes of reducing the peak
flood stages for the top 15 sub -basins. These items were each evaluated for
implementation into the sub -basins based on the existing stormwater management
systems in place, the sub -basins topographic elevations, its relative location to receiving
water bodies/canals, the estimated location of the saltwater intrusion zone, and the
available open areas. Additionally, their capacity to remove volumes of stormwater
runoff from a sub -basin were described in this subsection and the effectiveness of their
implementation within a sub -basin will be further evaluated in the following sections.
7.2.1 Positive Drainage with Outfalls
Positive drainage systems are stormwater management systems which discharge
stormwater runoff directly into open bodies of water such as canals, lakes, and rivers.
This type of stormwater management system does not provide any form of pre-
treatment prior to discharge and is the least accepted practice in Miami -Dade County.
Numerous positive drainage systems exist within the City's limits and were constructed
prior to the advent of modern stormwater discharge regulation. These systems can
remain in place in the event that no additional impervious area or increase in post-
7-6
January 2011 City of Miami Phase I - Stormwater Management Master Plan
development discharges are experienced through a reparation or rehabilitation of an
existing system as compared to the original functioning system.
In the event that the capacity or contributing areas associated with a stormwater
management system are increased, these systems are then required to meet all of the
applicable quantity and quality criteria previously described. These criteria are often
met by converting these discharge only systems into systems which infiltrate and/or
injection stormwater runoff into the groundwater table.
The effectiveness of a positive drainage system is controlled by the size, length, and
associated capacity of the pipes and structures making up the system as well as the
stages within the system and that of the receiving water body.
The representation of these types of improvements in Attachment Z are shown as
polygons where these improvements may be implemented. The project prefix is
typically presented as PR.
7.2.2 Exfiltration Trenches
A drainage system utilizing exfiltration trenches is the most common system used in
South Florida to meet stormwater quantity and quality retention requirements.
Exfiltration trenches have a relatively low cost and are one of the least land intensive
stormwater drainage systems available. Their effectiveness is heavily dependent on
acceptable soil hydraulic conductivity, groundwater table elevations, and available
topographic elevations. Exfiltration trench systems can also provide additional
interconnectivity within an area as does a solid pipe system.
An exfiltration trench system consists of at least one catch basin or inlet that leads to a
perforated or slotted pipe laid in a bed of aggregate filter media, such as pea rock.
They can be placed below paved surfaces or at the bottom of retention areas and offer
a method of conveying stormwater runoff to the groundwater table in areas where
impervious areas have been greatly increased. Figure 7-1 shows a typical longitudinal
profile and cross section of an exfiltration trench.
The system typically includes a weir or control structure which retains a certain amount
of stormwater runoff and surcharges the perforated pipe and trench to induce exfiltration
into the surrounding native soil. Self-contained systems do not require a weir or control
structure, since the lowest inlet or catch basin inflow elevation acts as the surge
elevation, or control elevation, of the system.
Exfiltration trenches are deemed viable when soil hydraulic conductivity is greater than
1 X 10"5 cubic feet per second (cfs), per square foot (ft2) per foot (ft) of hydraulic head.
When good soil hydraulic conductivity is present, exfiltration trenches are viable when
the average wet season groundwater elevation (average October elevation in
Miami -Dade County) is at least one to two feet below the control elevation of the
drainage system.
7-7
January 2011
City of Miami Phase I - Stormwater Management Master Plan
PRO"'USCD RO?Dwa,
SUP,ACE ELEVATIET1
:LATER'
TADLE
BAFFLE —�
FILTER FADRIC
EtwELOPE
AGGRER TE
MEGA
MCMSLi1TTEB
PIPE
FILTEENVELR. FABRiCOPE _/
PROFILE
AGGREGAT
MCC[
WATER
TALE
FILTER FABRIC
EMVELOPC
AGGREGATE
MEDIA
a' MAX
�i:DTM
4' Nit!
"'- WIETF!'"�
CROSS
SECTION
TIT
2C' MAX
DEPTH
Figure 7-1 —Typical Exfiltration Trench Sections
For this SWMMP and as previously described, an extraction methodology has been
used to account for the volume of runoff managed by the exfiltration trench systems.
This methodology assumes that exfiltration trenches have the ability to extract or
exfiltrate up to 3.28 inches of rainfall depth over the area contributing to the exfiltration
trench. The total area contributing to an exfiltration trench has been based on the
length of exfiltration trench and an associated typical width of 320 ft along the length of
the exfiltration trench. An example calculation of the extraction potential of an
exfiltration trench system within a sub -basin is shown in Calculation Example 6-5.
Calculation Example 7-2 — Exfiltration Trench Extraction Volume Calculation Example
Given Exfiltration
Trench length and
Contributing Area
Exfiltration trench length for project = 4,000 If
Contributing width = 320 ft
Total drainage area = (4,000 If x 320 If) / 43,560 = 29.38 acres
Extraction=Volume for '
'`Exfiltration trench
Extraction depth per unit area = 3.28"
Prorated extraction depth = (3.28" x 29.38 acres) = 96.38 acre -in = 8.03 acre-ft
• Stib basin and 100-Year -
Peak Values
, .. .
Sub -basin - CC7-S-24
100-year Peak Stage = 10.81 ft-NGVD
100-year Peak Volume = 165.12 ac-ft
Revised 100-Year Peak `
Volume
Revised 100-year Peak Volume = (165.12 - 8.03) = 157.09 ac-ft
The representation of these types of improvements in Attachment Z are shown as lines
where these improvements may be implemented. The project prefix is presented as
PR.
7.2.3 Dry Retention Basins
Retention basins are dedicated areas with topographic elevations which are lower than
the surrounding areas and are often interconnected with stormwater collection systems
throughout the surrounding areas. These basins typically have a bottom elevation
7-8
January 2011 City of Miami Phase I - Stormwater Management Master Plan
which is a minimum of 1-foot higher than the high groundwater elevation for a given
area allowing them to remain dry during times of no rain. Dry retention basins are
typically designed to collect and store stormwater runoff in order to satisfy both water
quantity and quality requirements for a system/area. They can also be constructed in
combination with exfiltration trenches or injection wells which will reduce infiltration
times for the stored water and returning the basin to dry conditions.
Retention basins can require acquisition and maintenance of large tracts of land and are
often not readily available in highly urbanized areas such as those within the City of
Miami. These basins can often take the form of recreational areas such as parks which
do provide an additional benefit to the community in the form of green areas for City
residents.
These basins are viable when the topographic elevations are several feet above the
high water elevation in a given area and can result in a significant reduction in stages
with a large enough retention basin.
The capacity of a retention basin is based on the horizontal dimensions of the retention
basin and the depth between the bottom of the retention basin and the highest point at
which no discharge to adjacent areas is achieved. An example of the volumetric
capacity of a retention basin is shown in Calculation Example 7-3.
Calculation Example 7-3 — Retention Basin Volume Calculation Example
•
Retention Basin
Location Data
Sub -basin - CC7-S-21
Retention Basin Area = 10 acres
High groundwater elevation = 2.0 ft-NGVD (Average October Water Elevation)
Retention Basin bottom elevation = 3.0 ft-NGVD (Minimum 1-ft of distance from high groundwater)
Lowest adjacent grade elevation = 8.5 ft-NGVD
Retention Basin
Volumetric Capacity.
Available Volume = 10 acres x ( 8.5' - 3.0') = 55 acre-ft
Sub -basin`. and 100-Year
Peak•Values
Sub -basin - CC7-S-21
100-year Peak Stage = 11.21 ft-NGVD
100-year Peak Volume = 166.11 ac-ft
Revised 100-Year Peak
Volume
Revised 100-year Peak Volume = (166.11 - 55) = 111.11 ac-ft
The representation of these types of improvements in Attachment Z are shown as lines
where these improvements may be implemented. The project prefix is presented as
RB.
7.2.4 Injection Drainage Wells
An injection drainage well consists of a drilled hole into the Floridan aquifer to discharge
stormwater runoff into that portion of the aquifer that meets certain salinity and total
dissolved solids (TDS) requirements. Injection drainage wells are typically used only
when it is not practical to use exfiltration trenches because of low soil hydraulic
conductivity. Figure 7-2 shows a typical section of an injection drainage well.
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January 2011 City of Miami Phase I - Stormwater Management Master Plan
Injection drainage wells can be categorized as injection wells under gravity or injection
wells under pressure. Injection wells under gravity act under the hydraulic gradient
induced by gravity of the drainage system discharging to the well, whereas, injection
wells under pressure use an artificially applied hydraulic head induced via a stormwater
pump station. Well discharge capacity is determined in the field through testing by a
certified well drilling contractor.
STEEL WELL GRATE
DESIGN WATER TABLE
BAFFLE
INFLOW PIPE
AVERAGE YEARLY LLW
WATER ELEVATION
END OF PIPE
UNCASEO. WELL.
&7TTOU OF WELL •
Figure 7-2 — Typical Injection Drainage Well
With injection drainage wells present in a drainage system, DEP requires the use of a
passive control device, such as a weir, in order to provide a method of controlling the
total head at the drainage well or wells.
For this SWMMP, the capacity of a well to account for a given volume has been
determined based on the assumption that the injection wells for these future projects will
be used for water quantity purposes. In general, the capacity of these wells within the
City of Miami often range between 300 and 800 gallons per minute (gpm) per foot of
head - 500 gpm per foot of head was used for this SWMMP. Additionally, the effect of a
phenomena known as mounding also has an effect on the capacity of an injection well.
This phenomena typically requires that an additional 1.5-ft of head is required in order to
overcome the difference in density between the fresh water resulting from a storm event
and the saltwater encountered in the saltwater intrusion zone. This effectively reduces
the peak flow of an injection well at a given stage and increases the stage at which flow
into the well begins - 3.5 ft-NGVD for most areas within the saltwater intrusion zone.
Moreover, the volumetric capacity of a well must be defined for a given time period for
which the injection well will be operational at or near peak capacity. This time period is
dependent on the critical design storm event for which their use will be analyzed - in this
case the 100-year, 72-hour event was the critical design storm event. In a conservative
approach, it was assumed that the total volume to be injected to the wells will be
equivalent to a capacity of 50% the peak discharge rate for an 18 hour period.
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January 2011
City of Miami Phase I - Stormwater Management Master Plan
An example of the volumetric capacity of an injection well system based on these
considerations is shown in Calculation Example 7-4.
Calculation Example 7-4 — Injection Well Volume Calculation Example
Given Injection Well
Data
Injection well capacity = 500 gpm per foot of head
Groundwater elevation = 2 ft-NGVD
Mounding effect = 1.5 ft of additional head required
Total number of injection wells = 30
Injection'Well Extraction '
Volume
Peak Flow Rate = 500 gpm x (8.0' - ( 2.0' + 1.5' ) ) = 2,250 gpm per well = 135,000 gallons per hour
(GPH)
Total Volume per well = 135,000 GPH x 50% x 18 hours = 1,215,000 gallons = 3.73 acre-ft
Total Extraction Volume for system = 3.73 acre-ft x 40 wells = 111.9 acre-ft
Sub-basimand 100-Year
+: Peak;Values:
...i
Sub -basin - CC6-N-12
100-year Peak Stage = 6.80 ft-NGVD
100-year Peak Volume = 171.28 ac-ft
Revised 10D-Year Peak . "
Volume
Revised 100-year peak volume = (171.28 - 111.9) = 59.38 ac-ft
The representation of these types of improvements in Attachment Z are shown as
large circles where these improvements may be implemented. The project prefix is
presented as PW when under gravity or with the prefix PS when in combination with a
pump station.
7.2.5 Pump Stations
Pump stations are used for expediting flows to a receiving water body or reservoir or to
induce a higher hydraulic head on injection drainage wells in locations where
topographic elevations are too low and/or groundwater elevations are too high to
effectively use the full capacity of a drainage well. Although stormwater pump stations
are expensive to install, operate, and maintain their use is often required in areas where
no other practical gravity alternative is available. Figure 7-3 shows a typical detail of a
stormwater pump station.
Numerous factors play a role in determining the potential volume for which a pump
station can extract and because the pump stations are often used in combination with
injection wells or are limited due to pre versus post volumetric and rate restrictions, their
capacity can more correctly be determined based on the capacity of the systems
receiving the flows they produce. The volume of removal will be based on the injection
wells or receiving retention basin being used in combination with these pumps.
WET WELL GRATBAR VALVEE FITTINGS-. BOX I/
PUMPS
Figure 7-3 — Typical Stormwater Pump Station Plan
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January 2011 City of Miami Phase I - Stormwater Management Master Plan
The representation of these types of improvements in Attachment Z are shown as
polygons where these improvements may be implemented. The project prefix is
presented as PS.
7.3 Capital Improvement Project Formulation
The following sub -sections describe and evaluate the top 15 sub -basins based on the
analysis and ranking procedures for this SWMMP update. Each sub -basin was
evaluated in terms of topography, location relative to receiving water bodies, existing
infrastructure, and feasibility of implementation of stormwater management systems.
A general description of the topography of each sub -basin was based on the LiDAR
based DEM available from Miami -Dade County DERM. This DEM provided the
topographic nature of a sub -basin and aided in understanding the main reason why
most areas experience flood conditions during heavy storm events.
Additionally, existing stormwater infrastructure was described based on the available
City of Miami Stormwater Atlas sheets and GIS based coverage of the City's stormwater
management system. Although antiquated in terms of the items detailed within these
data sets, much of the systems in shown remain the same throughout the City and the
general location and capacity of the existing systems can be cursorily evaluated using
these documents and data sets.
Each sub -basin was evaluated for the feasibility of implementing a stormwater
management system which would maximize the number of properties benefiting from
the improvements. In most cases, the minimum target for improvement was to remove
25% of the properties experiencing flooding from the flood plain.
7.3.1 Volumetric Analysis
The effectiveness of the proposed stormwater management system improvements
described in the following subsections were evaluated based on the stormwater
management system's capacity to remove stormwater in terms of volume from a sub -
basin. Each sub -basin's peak stage during the 100-year, 72-hour design storm event
was related to a peak volume based on the stage -area relationship for each sub -basin
defined within the XPSWMM models. This volume represented the total peak volume of
stormwater runoff within a sub -basin during the worst portion of the modeled design
storm event.
With regards to the proposed stormwater management system improvements, these
systems were described as having a specific capacity to remove stormwater from a sub -
basin either by retaining stormwater runoff or conveying runoff to the groundwater table.
This removal/storage capacity was then subtracted from the peak volume of a sub -basin
and related to a relative improvement goal which was based on stage. This
improvement goal was described as eliminating flood conditions for either 25% or 50%
of the properties within the sub -basin. The removal of flooded properties from the
floodplain was used due to its controlling factor in the scoring and ranking procedures
7-12
January 2011 City of Miami Phase I - Stormwater Management Master Plan
outlined within this SWMMP and are directly related to the other components in the
ranking procedure. A project specific volumetric analysis was not possible for each
single project proposed within a sub -basin because of the uncertainty with which the
projects will be implemented.
Additionally, it should be noted that although this analysis only accounts for the direct
affects of a project within a given sub -basin, ancillary benefits will also be realized when
constructed. More total sub -basin runoff will be accounted for and Tess will be taxing the
existing systems, especially those accounting for inter -basin transfers.
7.3.2 Rank #1 - Sub -Basin CC6-N-12
The topography for sub -basin CC6-N-12 is generally low with a depressed region which
runs from the northwest portion of the sub -basin towards the southeastern portion of the
sub -basin - see Figure 7-4. This sub -basin's topographic elevations are relatively low
when compared to most areas within the City.
Topography
--m. High
bane Low
Basin Boundary
Figure 7-4 — Sub -basin CC6-N-12 topographic trends
The main stormwater infrastructure components for this sub -basin are described as
follows:
• One trunk line runs along NW 36th Street from NW 19th Avenue to NW 37th
Avenue where it discharges into the C-6 Canal and extends beyond the City of
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January 2011 City of Miami Phase I - Stormwater Management Master Plan
Miami city limits. This trunk line begins as a 24-inch pipe increasing in size to a
5-ft x 5-ft rock trench based on the sketches from the City of Miami Atlas sheets.
Additionally, this main conveyance system appears to have been blocked at
some point by the Florida Department of Transportation (FDOT) as part of a
drainage improvement project along NW 36th Street (FDOT project number
87090-3552 - Reconstruction of NW 36th Street from NW 37th Court to NW 17th
Avenue). Based on these plans, there appears to be a retaining wall that was
constructed in the existing slab covered trench located on NW 36th Street just
east of NW 27th Avenue.
0 One trunk line runs along NW 22nd Avenue from SR 112 southward to the C-6
Canal. According the City of Miami Atlas sheets, the trunk line is a 6-ft trench
which increases to a 72-inch pipe prior to discharge.
The southern limit of this sub -basin is approximately 2,500-ft from the C-6 Canal. There
is an additional 3,200-ft from the approximate lowest point along NW 22nd Avenue at
NW 33rd Street to the southern limit of the basin.
The peak stage and volume based on the model results for the 100-year, 72-hour for
this sub -basin are presented in Table 7-5. Additionally, the 25°lo and 50% goals for this
sub -basin are also shown in this table.
Table 7-5 — Sub -basin CC6-N-12 Stage Reduction Estimates
Existing Condition
100-year peak flood stage
6.80 ft-NGVD
100-year peak flood volume
171.28 ac-ft
Number of flooded structures during 100-year design storm event
1,174
25% Flooded'Structure`Reduction
Peak stage to reduce number of flooded structures by 25%
6.44 ft-NGVD
Peak volume to reduce number of flooded structures by 25%
103.76 ac-ft
Total stage reduction
-0.36 ft
Total volume to be extracted
-67.53 ac-ft
Total reduction in the number of flooded structures at 25%
-294
50%-Flooded Structure'! Reduction
Stage to Reduce number of flooded structures by 50%
6.04 ft-NGVD
Peak volume to reduce number of flooded structures by 50%
56.16 ac-ft
Total stage reduction
-0.76 ft
Total volume to be extracted
-115.13 ac-ft
Total reduction in the number of flooded structures at 25%
-588
In this sub -basin, additional exfiltration trench will alleviate flood conditions for minor
storm events (less than a 5-year event) but a substantial volume of water is brought
towards low lying areas from overland flow and can easily overwhelm an exfiltration
trench system. Above ground storage appears to be physically and economically
unfeasible due to the large volume of water present during a large storm event (100-
year event) in addition to the highly urbanized nature of this sub -basin.
Possible solutions include removing the blockage introduced as part of the FDOT
project which appears to have eliminated one of the discharge points for this sub -basin.
Reintroducing this connection along NW 36th Street, providing a pump station to
expedite flows out of the sub -basin along 22nd Avenue, and providing additional
interconnectivity to the collection system ultimately connecting to the pump station, will
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January 2011 City of Miami Phase I - Stormwater Management Master Plan
reduce the stages primarily in the areas experiencing Tight to moderate. Additionally,
this sub -basin sits inside the saltwater intrusion zone and injection wells may also be
viable in expediting runoff to the groundwater in this sub -basin, especially with the use
of a pump station. The proposed improvements for this sub -basin as well as the
removal capacity of the proposed systems are shown in Table 7-6 and general
locations for these improvements are shown schematically in Attachment Z.
Table 7-6 — Sub -basin CC6-N-12 Proposed Stormwater Management System Components
Item
Quantity
Extraction Volume
(ac-ft)
Description! Comments
Pump Station
4
0 ac-ft
Pump stations capable of 17,000 gpm to increase the
hydraulic grade line for injection wells and expedite flow
to the wells.
Force Main
6,000-ft
0 ac-ft
Force main to connect pump stations to injection wells.
Exfiltration Trench
10,000-ft
20.08 ac-ft
will provide additional interconnectivity within the sub-
basin as well as convey runoff to the groundwater and
provide for water quality requirements.
Injection Wells
30
111.86 ac-ft
iNll convey runoff to the groundwater.
Total System Capacity
131.94 ac-ft
The total removal capacity of the proposed improvements results in an estimated
reduction in volume and stages which exceed the 50% flooded structure reduction
target. This results in an estimated reduction in stages of approximately -0.76 ft.
7.3.3 Rank #2 - Sub -Basin CC7-S-25
The topography for sub -basin CC7-S-25 is generally higher than other areas within the
City especially those areas surrounding the C-6 Canal. This sub -basin is generally flat
although there is a depressed region on the northern side of the sub -basin - see Figure
7-5.
Legend
Slonnwater System
s
r . . Topography
Kon
Figure 7-5 — Sub -basin CC7-S-25 topographic trends
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January 2011 City of Miami Phase I - Stormwater Management Master Plan
The main stormwater infrastructure components for this sub -basin are described as
follows:
9 The City of Miami Atlas sheets show a number of parallel lines run along NW
62nd Street from NW 7th Avenue to NW 17th Avenue. These parallel lines running
along NW 62nd Street include 18-inch, 24-inch, and 36-inch pipes and exfiltration
trenches. These lines connect to another line heading northward at the
intersection of NW 17th Avenue and NW 62nd Street. From this connection point,
there is a 30 to 60-inch line that runs northward to the C-7 Canal that is at a
distance of 12,000-ft from this point. The length and size of this trunk line is
assumed because the City of Miami Atlas sheets do not extend beyond the City
limits and do not show the actual discharge point.
o The City of Miami Atlas sheets show a trunk line that runs along NW 54th Street
from NW 19th Avenue to NW 7th Avenue. This trunk line consists of 54-inch to
96-inch pipes which run along NW 54th Street and then along NE 55th Terrace
and subsequently discharges into Biscayne Bay - approximately 10,000-ft. The
connection to this trunk line from the CC7-S-25 sub -basin is along NW 7th
Avenue via a 48-inch pipe. The same lines that were described previously
conveying runoff towards NW 17th Avenue along NW 62nd Street also conveys
runoff towards this 48-inch line.
This sub -basins relative distance from the nearest receiving water bodies, the C-7
Canal and Biscayne Bay, limits the number of viable large scale stormwater
management projects that would provide a significant decrease in flood stages for this
sub -basin.
The peak stage and volume based on the model results for the 100-year, 72-hour for
this sub -basin are presented in Table 7-7. Additionally, the 25% and 50°10 goals for this
sub -basin are also shown in this table.
Table 7-7 — Sub -basin CC7-S-25 Stage Reduction Estimates
Existing Condition
100-year peak flood stage
11.21 ft-NGVD
100-year peak flood volume
75.35 ac-ft
Number of flooded structures during 100-year design storm event
1,019
25% FloodedStructure-Reduction
Peak stage to reduce number of flooded structures by 25%
10.35 ft-NGVD
Peak volume to reduce number of flooded structures by 25%
27.13 ac-ft
Total stage reduction
-0.86 ft
Total volume to be extracted
-48.22 ac-ft
Total reduction in the number of flooded structures at 25%
-255
50%:FloodediStructure'Reduction• • -
Stage to Reduce number of flooded structures by 50%
9.96 ft-NGVD
Peak volume to reduce number of flooded structures by 50%
12.18 ac-ft
Total stage reduction
-1.25 ft
Total volume to be extracted
-63.18 ac-ft
Total reduction in the number of flooded structures at 25%
-515
As is the case for most all sub -basins, additional exfiltration trench will help alleviate
flood conditions for minor storm events (less than 5-year event) but larger storm events
can easily overwhelm an exfiltration trench system. Above ground storage within this
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January 2011 City of Miami Phase I - Stormwater Management Master Plan
sub -basin may be economically unfeasible due to the highly urbanized nature of this
sub -basin.
A possible solution for this sub -basin may be to develop a dry retention basin in a large
undeveloped property in the sub -basin to the north (sub -basin CC7-S-21, Ranked #3).
The specifics of this property will be discussed in the next subsection. For this sub -
basin to benefit from this dry retention basin, a pump station with a force main will need
to be implemented to carry runoff northward to this retention basin. The dry retention
basin would be approximately 4,000-ft from the lowest portion of this sub -basin.
Additional interconnectivity utilizing exfiltration trenches would also benefit in bringing
runoff to the pump station and expediting runoff to the groundwater table. The
proposed improvements for this sub -basin include the items listed in Table 7-8 and
general locations for these improvements are shown schematically in Attachment Z.
Table 7-8 — Sub -basin CC7-S-25 Proposed Stormwater Management System Components
Item
'Quantity
Extraction Volume
(ac-ft) . . _
Description/ Comments
Pump Station
1
33.00 ac-ft
Pump station capable of 20,000 gpm to deliver 33 ac-ft of
runoff to the dry retention basin in sub -basin CC7-S-21.
Force Main
4,000-ft
0 ac-ft
Force main to deliver flows from lowest portions of sub -
basin to the new dry retention basin in the sub -basin CC7-
S-21.
Ext ltration Trench
7,000-ft
14.06 ac-ft
Will provide additional interconnectivity within the sub-
basin as well as convey runoff to the groundwater and
provide for water quality requirements.
'Total System Capacity
47.06 ac-ft
The total removal capacity of the proposed improvements results in an estimated
reduction in volume and stages which approach the 25% flooded structure reduction
target. This results in an estimated reduction in stages approaching -0.86 ft.
7.3.4 Rank #3 - Sub -Basin CC7-S-21
Similar to sub -basin CC7-S-25, the topography for sub -basin CC7-S-21 is generally
higher than other areas within the City especially -those areas surrounding the C-6
Canal. This sub -basin has a depressed region on the eastern side of the sub -basin -
see Figure 7-6.
7-17
January 2011 City of Miami Phase I - Stormwater Management Master Plan
Legend
Stormwater Sys
Topography
sue- High
Law
Basin Boundary
li0
Figure 7-6 — Sub -basin CC7-S-21 topographic trends
The main stormwater infrastructure components for this sub -basin are described as
follows:
• The City of Miami Atlas sheets show a number of parallel lines run along NW
62nd Street from NW 7th Avenue to NW 17th Avenue. These parallel lines running
along NW 62nd Street include 18-inch, 24-inch, and 36-inch pipes and exfiltration
trenches. These lines connect to another line heading northward at the
intersection of NW 17th Avenue and NW 62nd Street. From this connection point,
there is a line that heads northward to the C-7 Canal that is at a distance of
12,000-ft from this point. The length and size of this trunk line is assumed
because the City of Miami Atlas sheets do not extend beyond the City limits
enough to show the actual discharge point.
• The City of Miami Atlas sheets show a line that runs along NW 715t Street from
NW 7th Avenue to NW 17th Avenue. This line is shown to be a 36-inch pipe with
exfiltration trenches and connect to another line heading northward at the
intersection of NW 17th Avenue and NW 71st Street. From this connection point,
there is a line that heads northward to the C-7 Canal that is approximately 9,000-
ft long. The length and size of this trunk line is assumed because the City of
Miami Atlas sheets do not extend beyond the City limits enough to show the
actual discharge point.
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January 2011 City of Miami Phase I - Stormwater Management Master Plan
o The City of Miami Atlas sheets also show the line that runs along NW 71st Street
from NW 17th Avenue to NW 7th Avenue connecting to a line on NW 7th Avenue.
This line begins as a 36-inch line and increases in size to a 54-inch where it
connects to a trunk line on NW 54th Street and NW 7th Avenue. This trunk line
consists of 60 to 96-inch pipes which run along NW 54th Street and then along
NE 55th Terrace and subsequently discharges into Biscayne Bay - approximately
10,000-ft. This is the same line that was described previously conveying runoff
towards from sub -basin CC7-S-25.
This sub -basins relative distance from the nearest receiving water bodies, the C-7
Canal and Biscayne Bay, limits the number of viable large scale stormwater
management projects that would provide a significant decrease in flood stages for this
sub -basin.
The peak stage and volume based on the model results for the 100-year, 72-hour for
this sub -basin are presented in Table 7-9. Additionally, the 25% and 50% goals for this
sub -basin are also shown in this table.
Table 7-9 — Sub -basin CC7-S-21 Stage Reduction Estimates
Existing Condition
100-year peak flood stage
11.21 ft-NGVD
100-year peak flood volume
166.11 ac-ft
Number of flooded structures during 100-year design storm event
827
25% Flooded Structure`Reductioo-; :.
Peak stage to reduce number of flooded structures by 25%
10.12 ft-NGVD
Peak volume to reduce number of flooded structures by 25%
43.03 ac-ft
Total stage reduction
-1.09 ft
Total volume to be extracted
-123.08 ac-ft
Total reduction in the number of flooded structures at 25%
-207
o%' Flooded -Structure `Reduction
i
Stage to Reduce number of flooded structures by 50%
9.20 ft-NGVD
Peak volume to reduce number of flooded structures by 50%
8.22 ac-ft
Total stage reduction
-2.01 ft
Total volume to be extracted
-157.89 ac-ft
Total reduction in the number of flooded structures at 25%
-414
A possible solution may be to create dry retention basins in areas of undeveloped land.
A large undeveloped area is present in an area bordered by NW 69th Street, NW 67th
Street, NW 7th Avenue, and NW 10th Avenue. This property is adjacent to a Miami
Dade County Water and Sewer facility and Northwestern High School. Based on
information gathered from the Miami Dade County Property appraisers office,. this
property is approximately 10 acres in size, has an assessed value of approximately $1.8
million, and has been undeveloped for over 10 years. With the Average October Water
Elevations at 2.0-ft NGVD for this sub -basin, a subsequent minimum dry retention basin
bottom elevation of 3.0-ft NGVD, and an average surface elevation of 8.5-ft NGVD, this
retention basin could provide a total of over 50 acre-ft of storage for this and adjacent
sub -basins. Additionally, this sub -basin sits approximately 3,000-ft from the estimated
boundary of the saltwater intrusion zone. With verification through testing, injection
wells may also be viable in expediting runoff to the groundwater at this site, especially
with the use of a pump station. The proposed improvements for this sub -basin include
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January 2011
City of Miami Phase I - Stormwater Management Master Plan
the items listed in Table 7-10 and general locations for these improvements are shown
schematically in Attachment Z.
Table 7-10 — Sub -basin CC7-S-21 Proposed Stormwater Management System Components
Item
Quantity
Extraction Volume
(ac-ft)
Description/ Comments
Pump Station
1
0 ac-ft
Pump station capable of 20,000 gpm to deliver 33 ac-ft of
runoff to the dry retention basin in sub -basin CC7-S-21.
Force Main
4,000-ft
0 ac-ft
Force main to deliver flows from lowest portions of sub -
basin to the new dry pond.
Exfiliration Trench
10,500 ft
21.08 ac-ft
Will provide additional interconnectivity within the sub -
basin as well as convey runoff to the groundwater.
Exfiltration trench will also be constructed in the dry
retention basin.
Dry Retention Basin
10 acres
17.00 ac-ft
Dry retention basin in undeveloped area with storage
capacity of up to 50 ac-ft - will be shared with sub -basin
CC7-S-25 where remaining 33 ac-ft are allocated.
Injection Wells
5
18.64 ac-ft
Will convey runoff to the groundwater.
Total System Capacity
56.72 ac-ft
The total removal capacity of the proposed improvements results in an estimated
reduction in volume of approximately less than half of the 25% flooded structure
reduction target. This results in an estimated reduction in stages of Tess than -0.40 ft.
7.3.5 Rank #4 - Sub -Basin C6-N-17
The general topography for sub -basin C6-N-17 is one of the lowest within the City. This
sub -basin also has depressed region on the southwestern side of the sub -basin which is
generally lower than the surrounding areas - see Figure 7-7.
Legend
Stommater System
Topography
H1r,
Figure 7-7 — Sub -basin C6-N-17 topographic trends
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January 2011 City of Miami Phase I - Stormwater Management Master Plan
The main stormwater infrastructure components for this sub -basin are described as
follows:
• The City of Miami Atlas sheets show a line running along NW 20th Street from
NW 22"d Avenue to NW 14th Avenue and beyond the sub -basin limits to 7th
Avenue. This line ranges in size from 24-inch to 42-inch pipes within the sub -
basin. This line connects to another line heading southward at the intersection of
NW 22nd Avenue and NW 20th Street. This pipe is shown to be a 60 to 72-inches
in size and heads southward to the C-6 Canal that is at a distance of 2,000-ft
from this intersection.
• The City of Miami Atlas sheets show a smaller line that runs along NW 24th
avenue that also connects the lines on NW 20th Street to that C-6. This line is
shown to be a 15-inch pipe and discharges to the C-6 Canal. This discharge
point is approximately 900-ft away from NW 20th Street
The peak stage and volume based on the model results for the 100-year, 72-hour for
this sub -basin are presented in Table 7-11. Additionally, the 25% and 50% goals for
this sub -basin are also shown in this table.
Table 7-11 — Sub -basin C6-N-17 Stage Reduction Estimates
ExistingCondition , '
100-year peak flood stage
5.78 ft-NGVD
100-year peak flood volume
186.70 ac-ft
Number of flooded structures during 100-year design storm event
829
25% Flooded StructureReduction ` .
Peak stage to reduce number of flooded structures by 25%
5.20 ft-NGVD
Peak volume to reduce number of flooded structures by 25%
93.61 ac-ft
Total stage reduction
-0.58 ft
Total volume to be extracted
-93.09 ac-ft
Total reduction in the number of flooded structures at 25%
-208
50%-Flooded Structure'Reduction
Stage to Reduce number of flooded structures by 50%
4.63 ft-NGVD
Peak volume to reduce number of flooded structures by 50%
39.87 ac-ft
• Total stage reduction
-1.15 ft
Total volume to be extracted
-146.82 ac-ft
Total reduction in the number of flooded structures at 25%
-415
This sub -basins relative distance from the C-6 Canal allows for the use of force mains in
combination with pump stations. The effectiveness of gravity mains is limited by the low
topographic elevations present in this sub -basin. This sub -basin also lies within the
saltwater intrusion zone which would allow for the use of injection wells in combination
with any pump stations. The proposed improvements for this sub -basin include the
items listed in Table 7-12 and general locations for these improvements are shown
schematically in Attachment Z.
7-21
January 2011
City of Miami Phase I - Stormwater Management Master Plan
Table 7-12 — Sub -basin C6-N-17 Proposed Stormwater Management System Components
Item
Quantity
Extraction Volume
(ac-ft)
Description/ Comments
Pump Station
4
0 ac-ft
Pump stations capable of up to 25,000 gpm to increase
the hydraulic grade line for the injection wells and
expedite flow to the wells.
Main
Forcebasin
5,000-ft
0 ac-ft
Force main to deliver flows from lowest portions of sub-
to the C-6 Canal.
Trench
Exfiltrationbasin
7,000 ft
14.06 ac-ft
Will provide additional interconnectivity within the sub-
as well as convey runoff to the groundwater.
Injection Wells
40
149.15
Will help convey runoff to the groundwater.
Total System Capacity
163.20 ac-ft
The total removal capacity of the proposed improvements results in an estimated
reduction in volume and stages which exceed the 50% flooded structure reduction
target. This results in an estimated reduction in stages of approximately -1.15 ft.
7.3.6 Rank #5 - Sub -basin CC7-S-24
Similar to sub -basin CC7-S-25, the topography for sub -basin CC7-S-24 is generally
higher than other areas within the City especially those areas surrounding the C-6
Canal. This sub -basin also has a depressed region bisecting the sub -basin which is
generally lower than the surrounding areas on both the eastern and western sides of the
sub -basin - see Figure 7-8.
Legend
Stormwater System
Topography
,serwsHeh
—. Low
Basin Boundary
:62NoisT?!`j,,, NE-OiSi.
!ram ..
Figure 7-8 — Sub -basin CC7-S-24 topographic trends
7-22
January 2011 City of Miami Phase I - Stormwater Management Master Plan
The main stormwater infrastructure components for this sub -basin are described as
follows:
• The City of Miami Atlas sheets show a 36" covered ditch that runs along NW 62nd
Street from NW 2nd Avenue to NE 2nd Avenue. This ditch is also connected to a
36-inch to 30-inch line that runs from NW 2nd Avenue to NW 5th Avenue. This
line appears to connect to a 54-inch to 60-inch line which runs southward to NE
54th Street and connects to the 96-inch line discharging into Biscayne Bay which
was previously described in the Section 7.3.4.
There appears to be a limited amount of interconnectivity within the stormwater
management system for this sub -basin, particularly in the low lying areas. Additionally,
the main trunk lines which discharge into Biscay Bay only service a small portion of this
sub -basin.
The peak stage and volume based on the model results for the 100-year, 72-hour for
this sub -basin are presented in Table 7-13. Additionally, the 25% and 50% goals for
this sub -basin are also shown in this table.
Table 7-13 — Sub -basin CC7-S-24 Stage Reduction Estimates
Existing Condition
100-year peak flood stage
10.81 ft-NGVD
100-year peak flood volume
165.12 ac-ft
Number of flooded structures during 100-year design storm event
747
25% Flooded Structure Reduction
Peak stage to reduce number of flooded structures by 25%
9.89 ft-NGVD
Peak volume to reduce number of flooded structures by 25%
49.24 ac-ft
Total stage reduction
-0.92 ft
Total volume to be extracted
-115.89 ac-ft
Total reduction in the number of flooded structures at 25%
-187
51 % Flooded Structure Reduction
Stage to Reduce number of flooded structures by 50%
9.09 ft-NGVD
Peak volume to reduce number of flooded structures by 50%
16.17 ac-ft
Total stage reduction
-1.72 ft
Total volume to be extracted
-148.95 ac-ft
Total reduction in the number of flooded structures at 25%
-374
For this sub -basin, injection wells under gravity may be used for this sub -basin because
it lies within the saltwater intrusion zone and the topographic elevations are high enough
relative to the groundwater level to provide adequate hydraulic head. The proposed
improvements for this sub -basin include the items listed in Table 7-14 and general
locations for these improvements are shown schematically in Attachment Z.
Table 7-14 — Sub -basin CC7-S-24 Proposed Stormwater Management System Components
Item
Quantity
Extraction Volume
(ac-ft)
Description/ Comments
Exfiltration Trench
4,000
8.03 ac-ft
Will provide additional interconnectivity within the
sub -basin as well as convey runoff to the
groundwater table.
Injection Wells
30
111.86 ac-ft
Will convey runoff to the groundwater.
Total System Capacity
119.89 ac-ft
7-23
January 2011 City of Miami Phase I - Stormwater Management Master Plan
The total removal capacity of the proposed improvements results in an estimated
reduction in volume and stages which approach the 25% flooded structure reduction
target. This results in an estimated reduction in stages of approximately -0.92 ft.
7.3.7 Rank #6 - Sub -Basin C4-S-17
This sub -basin suffers from generally low topographic elevations primarily in the central
portion- see Figure 7-9. The depressed regions within this sub -basin are also within a
close distance (1 to 2-feet) from the Average October Water Elevation (approximately
3.2-ft NGVD) for this area.
Legend
Stormwater System
Topography
mvolr High
61* 7+;
Law
Basin Boundary
Figure 7-9 — Sub -basin C4-S-17 topographic trends
The main stormwater infrastructure components for this sub -basin are described as
follows:
o The Flagami/West End Stormwater Pump Stations project was constructed to
serve this area during times of heavy rainfall. This system utilizes four pump
stations and an interconnected stormwater management system to collect and
discharge stormwater into the C-4 canal.
• The interconnectivity within the sub -basin covers the majority of the low lying
areas although certain areas in the west side of the sub -basin are without
collection systems.
7-24
January 2011 City of Miami Phase I - Stormwater Management Master Plan
This basin benefits from an interconnected system as well as four pump stations.
Although this stormwater management system exists, it is typical for systems of this
type to be designed for smaller events such as a 5- to 10-year event rather than the
100-year event which drives this sub -basins high ranking within this analysis.
The peak stage and volume based on the model results for the 100-year, 72-hour for
this sub -basin are presented in Table 7-15. Additionally, the 25% and 50% goals for
this sub -basin are also shown in this table.
Table 7-15 — Sub -basin C4-S-17 Stage Reduction Estimates
Existing Condition
100-year peak flood stage
6.95 ft-NGVD
100-year peak flood volume
441.47 ac-ft
Number of flooded structures during 100-year design storm event
697
25% Flooded Structure Reduction
Peak stage to reduce number of flooded structures by 25%
5.76 ft-NGVD
Peak volume to reduce number of flooded structures by 25%
205.43 ac-ft
Total stage reduction
-1.19 ft
Total volume to be extracted
-236.04 ac-ft
Total reduction in the number of flooded structures at 25%
-175
50% Flooded Structure Reduction
Stage to Reduce number of flooded structures by 50%
5.22 ft-NGVD
Peak volume to reduce number of flooded structures by 50%
133.93 ac-ft
Total stage reduction
-1.73 ft
Total volume to be extracted
-307.54 ac-ft
Total reduction in the number of flooded structures at 25%
-349
Improvements for this basin would most likely include additional gravity outfalls to help
expedite flows to the C-4 canal that would work as emergency overflows in case of
extreme events and additional exfiltration trench on the westem portion of the sub -
basin. The proposed improvements for this sub -basin include the items listed in Table
7-16 and general locations for these improvements are shown schematically in
Attachment Z.
Table 7-16 — Sub -basin C4-S-17 Proposed Stormwater Management System Components
Item
Quantity
Extraction Volume
(ac-ft)
Description/ Comments
Solid Pipe
6D0 If
0 ac-ft
Will provide additional locations to bring runoff to the
C-4 canal.
Outfall headwalls with
backflow preventers
3
119.00 ac-ft
Gravity outfalls to expedite flows to the C-4 canal
with backflow preventers (assuming 40 cfs
discharge rate per 36-inch outfall 12 hours) .
Exflltration Trench
5,500 If
11.04 ac-ft
Will provide additional interconnectivity within the
sub -basin as well as convey runoff to the
groundwater table and provide for water quality
requirements.
Total System Capacity
130.04 ac-ft
The total removal capacity of the proposed improvements results in an estimated
reduction in volume of approximately half of the 25% flooded structure reduction target.
This results in an estimated reduction in stages of less than -0.60 ft.
7-25
January 2011
City of Miami Phase I - Stormwater Management Master Plan
7.3.8 Rank #7 - Sub -Basin CC6-N-11
This sub -basin benefits from generally higher topographic elevations as compared to
the majority of the sub -basins within the City - see Figure 7-10. A depressed region
within this sub -basin exists on the western side of the sub -basin.
Legend
Stormwater System
Topography
Kph
lei
Basin Boundary
Figure 7-10 — Sub -basin CC6-N-11 topographic trends
The main stormwater infrastructure components for this sub -basin are described as
follows:
• The City of Miami atlas sheets show a major line which lies on NW 54th Street
and sits on the northern border of the CC6-N-11 sub -basin which is also the
southern border of the CC7-S-25 sub -basin (Ranked #2). This trunk line consists
of 54 to 60-inch line which then increases to a 96-inch pipes which run along NW
54th Street and then along NE 55th Terrace and subsequently discharges into
Biscayne Bay - approximately 10,000-ft. The connection to this trunk line from
the CC6-N-11 sub -basin is along NW 7th Avenue via a 48-inch pipe and along
and another line which lies along NW 12th Avenue which does not have a size
referenced in the atlas sheets.
• Another line runs east -west along NW 46th Street. The atlas sheets do not show
a pipe or trench size for this line but it is shown to connect to the line which runs
north -south on NW 17th Avenue. This line also does not have a size shown on
the atlas sheets until just prior to the NW 54th Street (no connection to the NW
54th Street system is shown). From this point the line is shown to be a 3-foot
trench, reducing to a 18-inch line then incrementally increasing in size to a 60-
7-26
January 2011 City of Miami Phase I - Stormwater Management Master Plan
inch line. This line heads northward to the C-7 Canal that is at a distance of
17,000-ft from the intersection on NW 46th Street. The length and size of this
trunk line is assumed because the City of Miami Atlas sheets do not extend
beyond the City limits enough to show the actual discharge point.
This basin is bordered on the south and west sides by SR 112/Airport Expressway and
1-95, respectively. The closest receiving water body, Biscayne Bay, is approximately
1.4 miles away and the system connecting discharging to Biscayne Bay is effectively
shared by several sub -basins.
The peak stage and volume based on the model results for the 100-year, 72-hour for
this sub -basin are presented in Table 7-17. Additionally, the 25% and 50% goals for
this sub -basin are also shown in this table.
Table 7-17 — Sub -basin CC6-N-11 Stage Reduction Estimates
Existing Condition
100-year peak flood stage
9.75 ft-NGVD
100-year peak flood volume
98.14 ac-ft
Number of flooded structures during 100-year design storm event
839
25% Flooded Structure Reduction
Peak stage to reduce number of flooded structures by 25%
9.52 ft-NGVD
Peak volume to reduce number of flooded structures by 25%
73.32 ac-ft
Total stage reduction
-0.23 ft
Total volume to be extracted
-24.82 ac-ft
Total reduction in the number of flooded structures at 25%
-210
50% Flooded Structure Reduction
Stage to Reduce number of flooded structures by 50%
9.08 ft-NGVD
Peak volume to reduce number of flooded structures by 50%
41.53 ac-ft
Total stage reduction
-0.67 ft
Total volume to be extracted
-56.61 ac-ft
Total reduction in the number of flooded structures at 25%
-420
This sub -basin is essentially land locked making developing additional outfalls
exceedingly difficult and costly. Although the majority of this sub -basin also lies outside
of the saltwater intrusion zone, it may be possible to utilize injection wells with
subsurface verification. Due of these limitations, improvements for this basin would
most likely include injections wells under gravity in the eastern portions of the sub -basin
and exfiltration trenches particularly in the southwestern portion of the sub -basin where
limited stormwater management systems exist. The proposed improvements for this
sub -basin include the items listed in Table 7-18 and general locations for these
improvements are shown schematically in Attachment Z.
Table 7-18 — Sub -basin CC6-N-11 Proposed Stormwater Management System Components
Item
Quantity
Extraction Volume
E-ft
Description/ Comments
Exflltration Trenches
15,000-If
30.12 ac-ft
Will provide additional interconnectivity within the
sub -basin as well as convey runoff to the
groundwater table and provide for water quality
requirements.
Injection Wells
7
26.10 ac-ft
Will convey runoff to the groundwater,
Total System Capacity
56.22 ac-ft
7-27
January 2011 City of Miami Phase I - Stormwater Management Master Plan
The total removal capacity of the proposed improvements results in an estimated
reduction in volume and stages which approach the 50% flooded structure reduction
target. This results in an estimated reduction in stages of approximately -0.67 ft.
7.3.9 Rank #8 - Sub -Basin C6-S-12
This sub -basin's topographic elevations are one of the lowest within the City - see
Figure 7-11. The sub -basin's elevations are also uniform throughout its limits although
there is an increase in elevations in the area on the southeastern portion of the sub -
basin.
Topography
�- High
1".- Low
Basin Boundary
Figure 7-11 — Sub -basin C6-S-12 topographic trends
The main stormwater infrastructure components for this sub -basin are described as
follows:
• The City of Miami atlas sheets show some interconnectivity throughout the sub -
basin with a single outfall located on NW 32nd Avenue discharging to the C-4.
This outfall appears to be a 24-inch outfall based on the closest pipe with a
referenced dimension.
This sub -basin is bordered on the north by the C-4 Canal, the closest receiving water
body.
7-28
January 2011
City of Miami Phase I - Stormwater Management Master Plan
The peak stage and volume based on the model results for the 100-year, 72-hour for
this sub -basin are presented in Table 7-19. Additionally, the 25% and 50% goals for
this sub -basin are also shown in this table.
Table 7-19 — Sub -basin C6-S-12 Stage Reduction Estimates
Existing Condition
100-year peak flood stage
5.11 ft-NGVD
100-year peak flood volume
107.10 ac-ft
Number of flooded structures during 100-year desiqn storm event
730
25% Flooded Structure Reduction
Peak stage to reduce number of flooded structures by 25%
4.55 ft-NGVD
Peak volume to reduce number of flooded structures by 25%
48.20 ac-ft
Total stage reduction
-0.56 ft
Total volume to be extracted
-58.91 ac-ft
Total reduction in the number of flooded structures at 25%
-183
50% Flooded Structure Reduction
Stage to Reduce number of flooded structures by 50%
4.01 ft-NGVD
Peak volume to reduce number of flooded structures by 50%
16.41 ac-ft
Total stage reduction
-1.10 ft
Total volume to be extracted
-90.70 ac-ft
Total reduction in the number of flooded structures at 25%
-366
The relative location of stormwater infrastructure within this sub -basin may be better
served with additional infrastructure increasing the interconnectivity within the basin and
providing an additional outfall which would increase the rate of discharges from this
basin to the C-4 Canal. Additionally, this sub -basin lies within the saltwater intrusion
zone which would allow for the use of injections wells for stormwater management
purposes. The use of wells would only be possible in combination with a pump station
due to the low topographic elevations within the sub -basin. The proposed
improvements for this sub -basin include the items listed in Table 7-20 and general
locations for these improvements are shown schematically in Attachment Z.
Table 7-20 — Sub -basin C6-S-12 Proposed Stormwater Management System Components
Item
Quantity
Extraction Volume
(ac-ft)
Description/ Comments
Force Main
2,500-ft
0 ac-ft
Force main to connect pump stations to injection wells.
Injection Wells
20
74.57 ac-ft
Will convey runoff to the groundwater table.
Pump Station
2
0 ac-ft
Pump stations capable of up to 23,000 gpm to increase
the hydraulic grade line for the injection wells and
expedite flow to the wells.
Exfiltration Trenches
7,000-If
12.05 ac-ft
Will provide additional interconnectivity within the sub-
basin as well as convey runoff to the groundwater table
and provide for water quality requirements.
Total System Capacity
86.62 ac-ft
The total removal capacity of the proposed mprovements results in an estimated
reduction in volume and stages which approach the 50% flooded structure reduction
target. This results in an estimated reduction in stages of approximately -1.10 ft.
7-29
January 2011
City of Miami Phase I - Stormwater Management Master Plan
7.3.10 Rank #9 - Sub -Basin CC4-S-21
This sub -basin's topographic elevations are generally higher than the surrounding sub -
basins to the north - see Figure 7-12. The northwestern portion of the sub -basin shows
lower elevations than the southwestern portions of the sub -basin.
Legend
Stormwater System
Figure 7-12 — Sub -basin CC4-S-21 topographic trends
The main stormwater infrastructure components for this sub -basin are described as
follows:
• The City of Miami atlas sheets show only small sections of stormwater
infrastructure within this basin. No major lines run within the body of the sub -
basin. The only major infrastructure shown is along West Flagler Street and
along SW 57th Avenue which appear to primarily serve these arterial roads.
This sub -basin primarily lacks a stormwater management system to help convey runoff
to the groundwater table and to prevent overland flow from affecting areas with lower
topographic elevations than adjacent areas. Additional, the closest receiving water
body to this sub -basin is the C-4 Canal which borders the sub -basins to the north and is
at a distance of 3,000 feet from the northernmost point of this sub -basin.
7-30
January 2011
City of Miami Phase I - Stormwater Management Master Plan
The peak stage and volume based on the model results for the 100-year, 72-hour for
this sub -basin are presented in Table 7-21. Additionally, the 25% and 50% goals for
this sub -basin are also shown in this table.
Table 7-21 — Sub -basin CC4-S-21 Stage Reduction Estimates
Existing Condition
100-year peak flood stage
9.39 ft-NGVD
100-year peak flood volume
369.28 ac-ft
Number of flooded structures during 100-year design storm event
639
25% Flooded Structure Reduction
Peak stage to reduce number of flooded structures by 25%
8.90 ft-NGVD
Peak volume to reduce number of flooded structures by 25%
269.31 ac-ft
Total stage reduction
-0.49 ft
Total volume to be extracted
-99.97 ac-ft
Total reduction in the number of flooded structures at 25%
-160
50% Flooded Structure Reduction
Stage to Reduce number of flooded structures by 50%
8.56 ft-NGVD
Peak volume to reduce number of flooded structures by 50%
213.60 ac-ft
Total stage reduction
-0.83 ft
Total volume to be extracted
-155.68 ac-ft
Total reduction in the number of flooded structures at 25%
-320
This sub -basin would benefit most from the implementation of stormwater management
systems throughout the sub -basin. This sub -basin also lies outside of the saltwater
intrusion zone which eliminates the use of injection wells. The proposed improvements
for this sub -basin include the items listed in Table 7-22 and general locations for these
improvements are shown schematically in Attachment Z.
Table 7-22 — Sub -basin CC4-S-21 Proposed Stormwater Management System Components
Item
Quantity
Extraction Volume
(ac-ft)
Description/ Comments
Exfiltration Trenches
24,000 If
48.19 ac-ft
Will provide additional interconnectivity within the sub -
basin as well as convey runoff to the groundwater,
Total System Capacity
48.19 ac-ft
The total removal capacity of the proposed improvements results in an estimated
reduction in volume of approximately half of the 25% flooded structure reduction target.
This results in an estimated reduction in stages of less than -0.25 ft.
7.3.11 Rank #10 - Sub -Basin CC7-S-26
The section of the City which lies within this sub -basin has topographic elevations which
are generally high - see Figure 7-13. This City section is in the southeastern portion of
the sub -basin.
7-31
January 2011
T1ST TE
City of Miami Phase I - Stormwater Management Master Plan
NW'T1ST.ST
NYf=san,sr
- t >t
NW T4TH+ST.
Legend
Stormwater Syste
Topography
�..++ Hvb
b1" Low
Basin Boundary
it
Figure 7-13 — Sub -basin CC7-S-26 topographic trends
The main stormwater infrastructure components for this sub -basin are described as
follows:
• The City of Miami atlas sheets show a trunk line running from west to east along
NW 54th Street towards NW 17th Avenue. This line is shown to be a 48 to 54-
inch line within the sub -basin and is the same line described previously to
continue along NW 54th Street and discharging to Biscayne Bay (described in
Section 0). The Bay is over 3 miles from NW 17th Avenue.
• A line is shown on NW 62nd Street which extends and connects to the system
which heads northward on NW 17th Avenue. This line is shown to be a 24 to 36-
inch line.
• The line going northward along NW 17th Avenue and connecting to the NW 62nd
Street system is shown to be a 60-inch line. This line heads northward to the C-7
Canal which is at a distance of 12,000-feet from this point.
This sub -basin primarily lacks a stormwater management system which extends beyond
the major roadways. Additionally, the closest receiving water body to this sub -basin is
the C-7 Canal which is exceedingly distant from the sub -basin.
January 2011
City of Miami Phase I - Stormwater Management Master Plan
The peak stage and volume based on the model results for the 100-year, 72-hour for
this sub -basin are presented in Table 7-23. Additionally, the 25% and 50% goals for
this sub -basin are also shown in this table.
Table 7-23 — Sub -basin CC7-S-26 Stage Reduction Estimates
Existing Condition
100-year peak flood stage
11.18 ft-NGVD
100-year peak flood volume
209.11 ac-ft
Number of flooded strictures during 100-year design storm event
545
25% Flooded Structure Reduction
Peak stage to reduce number of flooded structures by 25%
10.68 ft-NGVD
Peak volume to reduce number of flooded structures by 25%
171.59 ac-ft
Total stage reduction
-0.50 ft
Total volume to be extracted
-37.52 ac-ft
Total reduction in the number of flooded structures at 25%
-137
50% Flooded Structure Reduction
Stage to Reduce number of flooded structures by 50%
10.26 ft-NGVD
Peak volume to reduce number of flooded structures by 50%
140.08 ac-ft
Total stage reduction
-0.92 ft
Total volume to be extracted
-69.04 ac-ft
Total reduction in the number of flooded structures at 25%
-273
In the City of Miami portion of this sub -basin, additional exfiltration trench would benefit
by providing interconnectivity to the main systems. The proposed improvements for
City of Miami portion of this sub -basin include the items listed in Table 7-24 and general
locations for these improvements are shown schematically in Attachment Z.
Table 7-24 — Sub -basin CC7-S-26 Proposed Stormwater Management System Components
Item
Quantity
Extraction Volume
(ac-ft)
Description/ Comments
Exfihration Trenches
6,000-If
12.05 ac-ft
Will provide additional interconnectivity within the
sub -basin as well as convey runoff to the
groundwater.
Total System Capacity
12.05 ac-ft
The total removal capacity of the proposed improvements results in an estimated
reduction in volume of approximately less than one third of the 25% flooded structure
reduction target. This results in an estimated reduction in stages of Tess than -0.16 ft. It
should be noted that the improvement are negligible due to the fact that the majority of
the sub -basin lies outside of the City of Miami limits and improvements for these areas
were not proposed.
7.3.12 Rank #11 - Sub -Basin C4-S-18
This sub -basin's topographic elevations are generally low, particularly the areas
adjacent to the C-4 Canal and the northeastern areas of the sub -basin - see Figure
7-14.
7-33
January 2011
City of Miami Phase I - Stormwater Management Master Plan
Topography
Hiah
Basin Boundary
Figure 7-14 — Sub -basin C4-S-18 topographic trends
The main stormwater infrastructure components for this sub -basin are described as
follows:
o The Flagami/West End Stormwater Pump Stations project was constructed to
serve this area during times of heavy rainfall. This system utilizes four pump
stations and an interconnected stormwater management system to collect and
discharge stormwater into the C-4 canal. The pipe interconnectivity covers the
majority of the low lying areas although certain areas in the west side of the sub -
basin are without collection systems.
o The City of Miami atlas sheets show a trunk line running from south to north
along SW/NW 65th Avenue from SW 6th Street to the C-4 Canal. This line is
shown to be a 15 to 36-inch line.
o A line is shown on W Flagler Street which extends beyond the limits of the sub -
basin. A dimension is not shown for this line but is shown to connect to the line
running along SW/NW 65th Avenue.
This sub -basin benefits from an interconnected system as well as four pump stations.
7-34
January 2011
City of Miami Phase I - Stormwater Management Master Plan
The peak stage and volume based on the model results for the 100-year, 72-hour for
this sub -basin are presented in Table 7-25. Additionally, the 25% and 50% goals for
this sub -basin are also shown in this table.
Table 7-25 — Sub -basin C4-S-18 Stage Reduction Estimates
Existing Condition
100-year peak flood stage
7.19 ft-NGVD
100-year peak flood volume
886.00 ac-ft
Number of flooded structures during 100-year design storm event
432
25% Flooded Structure Reduction
Peak stage to reduce number of flooded structures by 25%
6.88 ft-NGVD
Peak volume to reduce number of flooded structures by 25%
815.99 ac-ft
Total stage reduction
-0.31 ft
Total volume to be extracted
-70.01 ac-ft
Total reduction in the number of flooded structures at 25%
-109
50% Flooded Structure Reduction
Stage to Reduce number of flooded structures by 50%
6.46 ft-NGVD
Peak volume to reduce number of flooded structures by 50%
721.20 ac-ft
Total stage reduction
-0.73 ft
Total volume to be extracted
-164.80 ac-ft
Total reduction in the number of flooded structures at 25%
-217
Although the stormwater management system that exists in this sub -basin is relatively
new, it is typical for systems of this type to be designed for smaller events such as a 5-
to 10-year event rather than the 100-year event which drives this sub -basins high
ranking within this analysis. Improvements for this basin would most likely include
additional gravity outfalls to help expedite flows to the C-4 Canal during extreme
conditions and would work as emergency overflows in case of pump failures. The
proposed improvements for this sub -basin include the items listed in Table 7-26 and
general locations for these improvements are shown schematically in Attachment Z.
Table 7-26 — Sub -basin C4-S-18 Proposed Stormwater Management System Components
Item
Quantity
Extraction Volume
(ac-ft)
Description/ Comments
Exfiltration Trench
1,200-If
2.41 ac-ft
Will provide additional interconnectivity within the
sub -basin as well as convey runoff to the
groundwater and provide for water quality
requirements.
Solid Pipe
400-If
0 ac-ft
Will provide additional locations to bring runoff to
the C-4
Outfall with
backfl headwallsw preventwit
ers
2
79.34 ac-ft
Gravity outfalls to expedite flows to the C-4 canal
with backflow preventers (assuming 40 cfs
discharge rate per 36-inch outfall 12 hours) .
Total System Capacity
81.75 ac-ft
The total removal capacity of the proposed improvements results in an estimated
reduction in volume and stages which exceed the 25% flooded structure reduction
target. This results in an estimated reduction in stages of approximately -0.31 ft.
7.3.13 Rank #12 - Sub -Basin C4-S-23
This sub -basin's topographic elevations are generally low, particularly the northern
2/3rds of the sub -basin - see Figure 7-15.
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January 2011
City of Miami Phase I - Stormwater Management Master Plan
Topography
v w High
Low
Basin Boundary
Figure 7-15 — Sub -basin C4-S-23 topographic trends
The main stormwater infrastructure components for this sub -basin are described as
follows:
• The City of Miami atlas sheets show a trunk line running along NW 4th Terrace
from NW 47th Avenue to NW 53rd Avenue. This line is shown to be a 21 to 36-
inch line. This line connects to another line running along NW 52nd Avenue, This
line begins at the intersection of NW 4th Terrace and NW 52nd Avenue and is
shown to be a 36 to 54-inch line with an outfall to the C-4 Canal.
o This sub -basin benefits from the Antonio Maceo Park pump station. The pump
station sits in a park adjacent to the C-4 Canal and the project consisted of
providing connections to the existing system in various locations in order to
expedite flows to the C-4 Canal.
The peak stage and volume based on the model results for the 100-year, 72-hour for
this sub -basin are presented in Table 7-27. Additionally, the 25% and 50% goals for
this sub -basin are also shown in this table.
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January 2011 City of Miami Phase I - Stormwater Management Master Plan
Table 7-27 — Sub -basin C4-S-23 Stage Reduction Estimates
Existing Condition
100-year peak flood stage
6.30 ft-NGVD
100-year peak flood volume
141.33 ac-ft
Number of flooded structures during 100-year design storm event
280
25% Flooded Structure Reduction
Peak stage to reduce number of flooded structures by 25%
5.69 ft-NGVD
Peak volume to reduce number of flooded structures by 25%
96.76 ac-ft
Total stage reduction
-0.61 ft
Total volume to be extracted
-44.58 ac-ft
Total reduction in the number of flooded structures at 25%
-71
50% Flooded Structure Reduction
Stage to Reduce number of flooded structures by 50%
5.01 ft-NGVD
Peak volume to reduce number of flooded structures by 50%
53.64 ac-ft
Total stage reduction
-1.29 ft
Total volume to be extracted
-87.69 ac-ft
Total reduction in the number of flooded structures at 25%
-141
Although the stormwater management system that exists in this sub -basin is relatively
new, it is typical for systems of this type to be designed for smaller events such as a 5-
to 10-year event rather than the 100-year event which drives this sub -basins high
ranking within this analysis. This sub -basin would benefit from additional exfiltration
trench on the south side of the basin to prevent overland runoff from being conveyed to
the lower lying areas as well as additional gravity outfalls to the C-4 Canal. The
proposed improvements for this sub -basin include the items listed in Table 7-28 and
general locations for these improvements are shown schematically in Attachment Z.
Table 7-28 — Sub -basin C4-S-23 Proposed Stormwater Management System Components
Item
Quantity
Extraction Volume
(ac-ft)
Description/ Comments
Exfiltration Trench
4,000-If
8.03 ac-ft
Will convey runoff to the groundwater.
Solid Pipe
400-If
0 ac-ft
Will provide additional locations to bring runoff to the
C-4
Outfall headwalls with
backflow preventers
2
79.34 ac-ft
Gravity outfalls to expedite flows to the C-4 canal
with backflow preventers (assuming 40 cfs discharge
rate per 36-inch outfall 12 hours) .
Total System Capacity
87.37 ac-ft
The total removal capacity of the proposed improvements results in an estimated
reduction in volume and stages which approach the 50% flooded structure reduction
target. This results in an estimated reduction in stages of approximately -1.29 ft.
7.3.14 Rank #13 - Sub -Basin CS-SS-3
This sub -basin's topographic elevations are generally higher than the surrounding sub -
basins to the north and west - see Figure 7-16. The northwestern portion of the sub -
basin shows lower elevations than the southeastern portions of the sub -basin although
they are higher than the elevations of the sub -basin to the north.
7-37
January 2011
City of Miami Phase I - Stormwater Management Master Plan
Topography
.+e.�. High
Lav
Basin Boundary
Figure 7-16 — Sub -basin C5-S5-3 topographic trends
The main stormwater infrastructure components for this sub -basin are described as
follows:
• The City of Miami atlas sheets show only small sections of stormwater
infrastructure within this basin. No major lines run within the body of the sub -
basin. The only major infrastructure shown is along West Flagler Street, NW 7th
Street, and NW 37th Avenue which appear to primarily serve these arterial roads.
This sub -basin primarily Tacks a stormwater management system to help convey runoff
to the groundwater table and to prevent overland flow from affecting adjacent areas with
lower topographic elevations. Additionally, the closest receiving water body to this sub -
basin is the C-5 Canal which borders the sub -basins to the north and is at a distance of
2,500 feet from the northernmost point of this sub -basin. This is the discharge point for
the system along NW 37th Avenue.
The peak stage and volume based on the model results for the 100-year, 72-hour for
this sub -basin are presented in Table 7-29. Additionally, the 25% and 50% goals for
this sub -basin are also shown in this table.
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January 2011
City of Miami Phase I - Stormwater Management Master Plan
Table 7-29 — Sub -basin C5-S5-3 Stage Reduction Estimates
Existing:Condition
100-year peak flood stage
10.21 ft-NGVD
100-year peak flood volume
5.02 ac-ft
Number of flooded structures during 100-year design storm event
470
25% Flooded ;Structure.Reduction ..,
Peak stage to reduce number of flooded structures by 25%
9.78 ft-NGVD
Peak volume to reduce number of flooded structures by 25%
1.56 ac-ft
Total stage reduction
-0.43 ft
Total volume to be extracted
-3.46 ac-ft
Total reduction in the number of flooded structures at 25%
-118
50%Flood ed.Structure Reduction ;:
Stage to Reduce number of flooded structures by 50%
9.36 ft-NGVD
Peak volume to reduce number of flooded structures by 50%
0.47 ac-ft
Total stage reduction
-0.85 ft
Total volume to be extracted
-4.55 ac-ft
Total reduction in the number of flooded structures at 25%
-236
This sub -basin would benefit from the implementation of a stormwater management
system to help convey runoff to the groundwater table. The high surface elevations and
low groundwater elevations would maximize the benefits of exfiltration trenches
throughout the sub -basin. The proposed improvements for this sub -basin include the
items listed in Table 7-30 and general locations for these improvements are shown
schematically in Attachment Z.
Table 7-30 — Sub -basin C5-S5-3 Proposed Stormwater Management System Components
item
Quantity
Extraction Volume ,:
•(ac-ft)'.
Description/ Comments
Exfiltration Trenches
5,000-If
20.08 ac-ft
Will convey runoff to the groundwater and
increase interconnectivity within the sub -basin.
" Total System Capacity -
20.08 ac-ft
The total removal capacity of the proposed improvements results in an estimated
reduction in volume and stages which approach the total excess volume experienced
during the 100-year event. This results in no flooding being experienced during the
100-year event.
7.3.15 Rank #14 - Sub -Basin CC6-S-8
This sub -basin's topographic elevations are generally higher than the surrounding sub -
basins to the north and west - see Figure 7-17. The northeastern portion of the sub -
basin shows lower elevations than the southeastern portions of the sub -basin. A low
lying area exists in the northeastern section of the sub -basin.
7-39
January 2011
City of Miami Phase I - Stormwater Management Master Plan
Legend
Stormwater System
Topography
High
YA7 Lou
Basin Boundary
Ulm
Figure 7-17 — Sub -basin CC6-S-8 topographic trends
The main stormwater infrastructure components for this sub -basin are described as
follows:
• The City of Miami atlas sheets show various sections of stormwater infrastructure
primarily in the northern half of this sub -basin although no major lines run within
the body of the sub -basin.
This sub -basin primarily Tacks interconnectivity within the sub -basins systems to the
main conveyance systems discharging to the C-6 Canal, the closest receiving water
body at approximately 2,300 feet to the northwest.
The peak stage and volume based on the model results for the 100-year, 72-hour for
this sub -basin are presented in Table 7-31. Additionally, the 25% and 50% goals for
this sub -basin are also shown in this table.
7-40
January 2011
City of Miami Phase 1- Stormwater Management Master Plan
Table 7-31 — Sub -basin CC6-S-8 Stage Reduction Estimates
Existing Condition
100-year peak flood stage
10.06 ft-NGVD
100-year peak flood volume
65.88 ac-ft
Number of flooded structures during 100-year design storm event
401
-25% Flooded: Structure: Reduction
Peak stage to reduce number of flooded structures by 25%
9.64 ft-NGVD
Peak volume to reduce number of flooded structures by 25%
43.17 ac-ft
Total stage reduction
-0.42 ft
Total volume to be extracted
-22.71.ac-ft
Total reduction in the number of flooded structures at 25%
-101
50%- Flooded 'Structure- Reduction •
Stage to Reduce number of flooded structures by 50%
9.25 ft-NGVD
Peak volume to reduce number of flooded structures by 50%
28.43 ac-fl
Total stage reduction
-0.81 ft
Total volume to be extracted
-37.45 ac-ft
Total reduction in the number of flooded structures at 25%
-201
The high topographic elevations would allow for efficient operation of exfiltration
trenches throughout the southern portions of the sub -basin. Additionally, this sub -basin
lies within the saltwater intrusion zone which would allow for the use of injections wells
under gravity. The proposed improvements for this sub -basin include the items listed in
Table 7-32 and general locations for these improvements are shown schematically in
Attachment Z.
Table 7-32 — Sub -basin CC6-S-8 Proposed Stormwater Management System Components
•Item
Quantity
Extraction Volume
;. (ac-ft)
'Description/'Comments .
Exftltration Trenches
4,000-If
8.03 ac-ft
Will provide additional interconnectivity within the
sub -basin as well as convey runoff to the
groundwater table.
Injection Wells
10
37.29 ac-ft
Will convey runoff to the groundwater.
Total System Capacity -
45.32 acft
The total removal capacity of the proposed improvements results in an estimated
reduction in volume and stages which exceed the 50% flooded structure reduction
target. This results in an estimated reduction in stages of approximately -0.81 ft.
7.3.16 Rank #15 - Sub -Basin DA1-SE-2
This sub -basin's topographic elevations are generally higher than the surrounding areas
to the south and west - see Figure 7-18. The northeastern portion of the sub -basin
shows higher elevations than the southeastern portions of the sub -basin although they
are higher than the elevations of the areas to the south. A low lying area exists in the
southwestern limits of the sub -basin.
7-41
January 2011
City of Miami Phase I - Stormwater Management Master Plan
II •
Legend
Stormwater System
Topography
High
Basin Boundary
Figure 7-18 — Sub -basin DA1-SE-2 topographic trends
The main stormwater infrastructure components for this sub -basin are described as
follows:
• The City of Miami atlas sheets show numerous sections of stormwater
infrastructure within this basin although no major lines connect to the major trunk
line running along SW 37th Avenue.
This sub -basin is primarily serviced by self contained systems which do not connect to
major lines discharging to a receiving water body. The southeastern portion of the sub -
basin lies within the saltwater intrusion zone which would allow for the use of injection
wells.
The peak stage and volume based on the model results for the 100-year, 72-hour for
this sub -basin are presented in Table 7-33. Additionally, the 25% and 50% goals for
this sub -basin are also shown in this table.
7-42
January 2011
City of Miami Phase I - Stormwater Management Master Plan
Table 7-33 — Sub -basin DA1-SE-2 Stage Reduction Estimates
Existing Condition
100-year peak flood stage
10.65 ft-NGVD
100-year peak flood volume
28.86 ac-ft
Number of flooded structures during 100-year design storrn event
201
25% Flooded Structure Reduction
Peak stage to reduce number of flooded structures by 25%
10.09 ft-NGVD
Peak volume to reduce number of flooded structures by 25%
16.56 ac-ft
Total stage reduction
-0.56 ft
Total volume to be extracted
-12.30 ac-ft
Total reduction in the number of flooded structures at 25%
-51
50% Flooded Structure Reduction
Stage to Reduce number of flooded structures by 50%
9.66 ft-NGVD
Peak volume to reduce number of flooded structures by 50%
11.16 ac-ft
Total stage reduction
-0.99 ft
Total volume to be extracted
-17.70 ac-ft
Total reduction in the number of flooded structures at 25%
-101
Injection wells would provide a significant benefit in this sub -basin due to the high
topographic elevations which would also maximize the discharge rate going into the
wells. An existing interconnected stormwater management system also exists which
would reduce the need for additional infrastructure within the sub -basin. The proposed
improvements for this sub -basin include the items listed in Table 7-34 and general
locations for these improvements are shown schematically in Attachment Z.
Table 7-34 — Sub -basin DA1-SE-2 Proposed Stormwater Management System Components
Item
Injection Wells
Quantity
10
Total System Capacity
Extraction Volume
(ac-ft)
37.29 ac-ft
37.29 ac-ft
Description/ Comments
Will convey runoff to the groundwater.
The total removal capacity of the proposed improvements results in an estimated
reduction in volume and stages which approach the total excess volume experienced
during the 100-year event. This results in no flooding being experienced during the
100-year event.
7.4 Planning -Level Cost Estimates
Stormwater management systems were devised for each of the top 15 ranked sub -
basins within the Phase I SWMMP limits of the City of Miami. Each project was
grouped based on the sub -basin in which it was contained in and the total planning -level
construction cost was calculated per project grouping. The specific projects can be
seen schematically in Attachment Z. The stormwater management systems proposed
for these sub -basins may be constructed in phases depending on funding availability
and engineering design and permitting constraints.
7.4.1 Cost Estimate Procedures & Unit Costs
Construction costs were calculated for individual or grouped projects. The goal of the
project grouping was to combine or present projects within proximity of one another and
with a total construction cost that would be manageable within the City's yearly budgets.
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January 2011 City of Miami Phase I - Stormwater Management Master Plan
These driving factors resulted in the majority of the construction cost for these projects
being below $2,000,000. Some projects such as pump stations with drainage wells
required exceeding this total cost.
There is also a land acquisition proposed for one of the sub -basins within this
Stormwater Management Master Plan. This is for a property within sub -basin CC7-S-21
and the acquisition cost for this property was based on the property appraiser value of
the property for 2010. The unit cost shown includes the cost of the property acquisition
and an estimated cost for developing the property.
Costs for labor and materials were based on unit pricing data from several sources,
including:
• FDOT Item Average Unit Cost,
• ADA's own proprietary unit cost database
In addition to the construction probable direct cost subtotal shown for each sub -basin,
maintenance of traffic, mobilization, CIP management, construction management,
permits, survey, design, and construction contingency have also been included in the
construction probable cost total and presented as follows:
• Probable Construction Cost Subtotal 1
1. Maintenance of Traffic - 5% of construction probable direct cost
2. Mobilization - 5% of construction probable direct cost
3. Construction Contingency - 20% of construction probable direct cost
• Probable Construction Cost Subtotal 2
1. Construction Management - 7.5% of Subtotal 1
2. Permits, Survey, & Design - 15% of Subtotal 1
3. CIP Management - 15% of Subtotal 1
Attachment AA provides a listing of all projects by sub -basin with each of these items
detailed in the table.
7.4.2 Cost Estimate Results
A summary of the Probable Construction Costs per sub -basin is shown in Table 7-35
and detailed probable construction costs with unit quantities for the grouped projects are
presented in Attachment AA. Each project referenced in this table refers to the
projects shown schematically in Attachment Z. It should be noted that the nature and
extent of the majority of these proposed projects allow for further phasing within the
project in order to allow for the funding allocations for the design and construction.
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January 2011
City of Miami Phase I - Stormwater Management Master Plan
Table 7-35 — Probable construction costs per sub -basin
Flood
Rank
Sub -basin
Probable
Construction
Cost Total ' A
1
CC6-N-12
$ 17,004,488
2
CC7-S-25
$ 7,020,406
3
CC7-S-21
$ 15,015,000
4
C6-N-17
$ 15,993,656
5
CC7-S-24
$ 5,724,469
6
C4-S-17
$ 3,410,550
7
CC6-N-11
$ 9,412,081
8
C6-S-12
$ 10,014,469
9
CC4-S-21
$ 13,803,075
10
CC7-S-26
$ 3,432,000
11
C4-S-18
$ 854,425
12
C4-S-23
$ 2,468,538
13
C5-S5-3
$ 2,866,256
14
CC6-S-8
$ 3,435,575
15
DA1-SE-2
$ 1,135,063
In total, all the projects presented for the top 15 ranked sub -basins within Phase I of this
SWMMP totals just over $111,000,000. Over 5-years, the average yearly funding
allocation requirement would be above $22,000,000 for the Phase I limits if all projects
were to be constructed with the 5-year period.
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January 2011
City of Miami Phase I - Stormwater Management Master Plan
The stormwater improvement projects presented in this SWMMP were devised with the
intent of providing the maximum benefit to the properties within the specific sub -basin
showing signs of extreme flooding based on the 100-year, 72-hour design storm event.
The procedure devised for ranking the proposed stormwater management
improvements was based on the probable construction cost and weighing that cost
versus the number of properties benefiting from the improvement. This procedure and
the revised sub -basin ranking is further described in the following subsections.
8.1 Ranking Procedure
The ranking procedure is based on two components which help to indentify and rank the
improvements that will affect the most properties at the lowest prorated cost.
The initial component in the ranking procedure required that the sub -basins be given an
importance factor. This importance factor was based on two criteria - the number of
properties affected and the percentage of the properties experiencing a benefit from the
proposed improvements. The following criteria was used as rules for each of the four
levels:
• Level 1 More than 300 properties affected and more than 50°l0 of the total
flooded properties affected
• Level 2 - More than 150 properties affected and more than 25% of the total
flooded properties affected
• Level 3 - More than 100 properties affected and more than 25% of the total
flooded properties affected
• Level 4 - all other sub -basins
The second component of the ranking procedure was based on the cost of the
improvement divided by the number of structures affected. This provided the
construction cost per structure realizing the benefit in terms of flooding. The purpose of
this component was to prioritize projects which affect the highest number of properties
at the lowest cost per structure. The probable construction costs per sub -basin
developed in the previous section were used for this portion of the ranking procedure.
The sub -basin were then ranked by the Importance Factor and then by the Cost per
Flooded Property Removed from Flood Plain - see Table 8-1. This new ranking helps
identify which sub -basin's groups of improvements will provide the highest return in
terms of flood protection at the lowest cost.
8.1.1 Ranking Results
The revised rankings are presented in Table 8-1. The revised ranking should be
utilized in conjunction with field reviews in order to physically verify the findings within
this SWMMP.
8-1
January 2011
City of Miami Phase I - Stormwater Management Master Plan
Table 8-1 — Probable construction costs per sub -basin
Flood
Rank
Sub-
basin
Probable
Construction
Cost Total
Affected
Properties
Percentage
of Flooded
Properties
Cost per
Flooded
Property
Removed from
Flood Plain
Importance
Factor
Revised
Ranking
13
C5-S5-3
$ 1,952,700
470
100
$ 4,154.68
1
1
7
CC6-N-11
$ 6,571,260
420
50
$ 15,645.86
1
2
1
CC6-N-12
$ 13,261,380
588
50
$ 22,553.37
1
3
4
C6-N-17
$ 12,794,430
415
50
$ 30,829.95
1
4
14
cc6-S-8
$ 2,580,960
201
50
$ 12,840.60
2
5
2
CC7-S-25
$ 5,094,000
255
25
$ 19,976.47
2
6
5
CC7-S-24
$ 4,618,560
187
25
$ 24,698.18
2
7
8
C6-S-12
$ 6,978,780
183
50
$ 38,135.41
2
8
11
C4-S-18
$ 628,260
109
25
$ 5,763.85
3
9
15
DA1-SE-2
$ 1,018,800
101
100
$ 10,087.13
3
10
12
C4-S-23
$ 1,721,772
141
50
$ 12,211.15
3
11
6
C4-S-17
$ 2,387,388
85
12
$ 28,086.92
4
12
10
CC7-S-26
$ 2,343,240
45
8
$ 52,072.00
4
13
9
CC4-S-21
$ 9,372,960
80
12
$ 117,162.00
4
14
3
CC7-S-21
$ 12,064,290
100
12
$ 120,642.90
4
15
8.2 5-Year Capital Improvement Plan
In order for the 5-year Capital Improvement Plan to be all-inclusive of the City's
mainland areas, the Capital Improvement Plan development process will be performed
under Phase II of the Stormwater Management Master Plan. This will result in all the
sub -basins being taken into account when allocating funds to specific projects within the
City based on the ranking procedures developed for Phase I and Phase II of the City of
Miami Stormwater Management Master Plans. Additionally, a more recent budget
allocation will be made available by the City during the development of Phase II which
will result in a dollar amount that is more representative of the City's current financial
condition. The quantities and costs within this Phase will be carried over directly to the
next phase of the SWMMP development. Attachment BB contains the re -ranked
construction cost estimated.
8.3 Conclusions & Recommendations
The extent of the flood conditions and the age of the stormwater management systems
within the City of Miami require significant funding in order to fully eliminate flooding
during extreme storm events such as a 100-year event. Constructing new systems
and/or reconstructing old or under capacity systems is the ideal situation but funding will
always be the determining factor in the decision making process of how, what, and
January 2011 City of Miami Phase I - Stormwater Management Master Plan
where to perform system expansions or upgrades. Additionally, with the ever more
stringent Federal, State, and local water quality requirements, these improvements will
require additional considerations and, in turn, additional costs.
The evaluations performed for this SWMMP take into account the areas that are in the
most need for improvements in order to alleviate flood conditions and improve the
overall function of the City's stormwater management systems. Each individual project
will provide incremental benefits not only to the sub -basin within which a project is to
reside but also provides an ancillary benefit to adjacent sub -basins. The ranking
procedures presented help to identify areas where improvements will provide the
highest rate of return in terms of removing properties from the flood plain during
extreme events.
It should also be noted that all projects within this revised ranking will also require
additional assessments and engineering analysis in order to verify the viability of these
projects which are often further constrained by geological or constructability issues.
Additionally, devising a stormwater management system capital improvement plan at
this time, without completing Phase II of the City of Miami's Stormwater Management
Master Plan, will improperly skew potential projects and funding to the areas in Phase I.
For this reason, leaving the development of the stormwater management system capital
Improvement plan to be developed under Phase II would provide the City with the most
comprehensive set of tools for determining the allocation of funds for the near future.