HomeMy WebLinkAboutExhibit 1Crystal Report Viewer
City of Miami
Text File Report
City Hall
3500 Pan American Drive
Miami, FL 33133
www.miamigov.com
File ID: 11-00081
Enactment #: R-11-0070
Version: 1
Type: Resolution Status: Passed
Enactment Date: 2/24/11
Introduced: 1/21/11 Controlling Body: Office of the City
Clerk
A RESOLUTION OF THE MIAMI CITY COMMISSION, WITH ATTACHMENT(S), ADOPTING
THE FINDINGS OF THE CITY OF MIAMI ("CITY") PHASE I STORMWATER MANAGEMENT
MASTER PLAN, DATED JANUARY 20, 2011, PREPARED BY ADA ENGINEERING, INC,
ALLOWING THE CITY TO IMPROVE ON ITS NATIONAL INSURANCE FLOOD
PROGRAM -COMMUNITY RATING SYSTEM WHICH ENABLES CITY RESIDENTS TO RECEIVE
DISCOUNTS ON FLOOD INSURANCE PREMIUM RATES; RECOMMENDING APPROVAL OF
THE FINDINGS, MEASURES AND LOCATIONS CONTAINED THEREIN.
WHEREAS, ADA Engineering, Inc. was tasked with completing Phase I and Phase II of the City of Miami's ("City's")
Stormwater Management Master Plan; and
WHEREAS, the primary objective ofthis study is to analyze areas of flood concem which impact public safety and
property loss; and
WHEREAS, in order for the City to improve its National Insurance Flood Program -Community Rating System
("NFIP-CRS") rating, the current plan would have to be updated within the previous five years; and
WHEREAS, by improving the NFIP-CRS rating from a Class 8 to a 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
WHEREAS, the findings will further allow the City to develop a comprehensive 5-year Capital Improvement Plan
identifying drainage improvement areas and enhancements; and
WHEREAS, Phase II of the plan is currently underway and is anticipated to be completed November, 2011;
NOW, THEREFORE, BE IT RESOLVED BY THE COMMISSION OF THE CITY OF MIAMI, FLORIDA:
Section 1. The recitals and findings contained in the Preamble to this Resolution are adopted by reference and
incorporated as if fully set forth in this Section.
Section 2. The findings of the City Phase I Stormwater Management Master Plan, dated January 20, 2011, prepared
by ADA Engineering, Inc., allowing the City to improve on its NFIP-CRS, which enables City residents to receive discounts
on flood insurance premium rates, are adopted.
Section 3. The City Commission further recommends approval of the findings, measures and locations contained
therein.
. http://egov.ci.miami.fl.us/LegistarWeb/temp/rep55E3.html[4/4/2012 11:20:09 AM]
Crystal Report Viewer
Section 4. This Resolution shall become effective immediately upon its adoption and signature of the Mayor. { 1 }
http://egov.ci.miami.fl.us/LegistarWeb/temp/rep55E3.html[4/4/2012 11:20:09 AM]
• Phase 1.1
Stormwater Mana
Master Plan
:Final
Prepared by:
tpkoc.rinzaDom4r-Agorcri
8550 NW 33rd Street, .Suite 101
Miami, Florida .33122
February 2012
ement
February2012 City of Miami
Phase II - Stormwater Management Master Plan Final
ii
February.2012
City of Miami
Phase II - Stormwater Management Master Plan Final
City of Miami
Phase .II Stormwater Management Master Plan
Final
ferof Oontents
1.0 EXECUTIVE SUMMARY 1-1
1.1 GENERAL BACKGROUND 1.1
1.2 DATA COLLECTION AND EVALUATION 1-4
1.3 DEVELOPMENT OF. DIGITAL TERRAIN MODEL 1-5
1.4 SUB -BASIN DELINEATION 1-5
1.5 EXISTING CONDITIONS MODEL DEVELOPMENT *1-6
1.6 IDENTIFICATION AND RANKING OF PROBLEM AREAS .1-7
1.7 EVALUATION OF FLOOD PROTECTION PROJECTS 1-7
1.8 FUTURE IMPROVEMENT PROJECT FORMULATION 1-8
1.9 RANKED SUB -BASINS WITH PROPOSED PROJECTS 1-9
1.10 PLANNING -LEVEL COST ESTIMATES 1-9
1.11 RANKING OF FUTURE PROJECTS & CAPITAL IMPROVEMENT PLAN .1-9
1.12 CITY STORMWATER INFRASTRUCTURE ATLAS UPDATE 1-11
2.0 INTRODUCTION 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 DATA FROM OTHER SOURCES 3-4
3.3.1 SOUTH FLORIDA WATER MANAGEMENT DISTRICT (SFWMD) 3-4
3.3.2 NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION (NOAA) 3-8
3.3.3 UNITED STATES ARMY CORPS OF ENGINEERS (USACE) 3-10
3.3.4 UNITED STATES GEOLOGICAL SURVEY (USGS) 3-10
3.3.5 NATURAL RESOURCES CONSERVATION SERVICE (NRCS) 3-11
3.3.6 FEDERAL EMERGENCY MANAGEMENT AGENCY (FEMA) 3-12
3.4 DATA EVALUATION 3-13
3:4.1 MIAMI-DADE COUNTY DERM DATA 3-13'
3.4.2 CITY OF MIAMI .DATA 3-16
3.4.3 SFWMD RAINFALL DATA 3.17
3.5 DATA COLLECTION & EVALUATION CONCLUSION 3-20
4.0 DEVELOPMENT OF DIGITAL TERRAIN MODEL 4-1
4.1 TOPOGRAPHIC DATA 4-1
4.2 DATUM SHIFT 4.2.
4.3 TIN CREATION 4-3
4.4 RASTER CREATION 4-5
4.5 RESULTING RASTER DATASET 4-6
4.6 DTM DEVELOPMENT CONCLUSION 4-8
5.0 SUB -BASIN DELINEATION 5-1
5.1 CITY OF MIAMI DELINEATION 5-1
5.2 CITY OF MIAMI INFRASTRUCTURE DATA 5-3
5.3 TOPOGRAPHIC DATA 5-5
5.4 DELINEATION METHODOLOGY 5-7
5.5 SUB -BASIN DEVELOPMENT CONCLUSION 5-12
6.0 EXISTING CONDITIONS MODEL DEVELOPMENT 6-1
6.1 RUNOFF BLOCK MODEL SETUP 6-3'
6.1.1 LAND USE 6-3
6.1.2 INFILTRATION 6-4
6.1.3 GROUNDWATER INFILTRATION 6-10
February.2012 City of Miami
Phase II - Stormwater Management Master Plan Final
6.1.4 RAINFALL 6-11
6.1.5 GROUNDWATER ELEVATIONS 6-12
6.2 HYDRAULICS BLOCK MODEL SETUP (EXTRAN BLOCK) 6-14
6.2.1 SETUP OF HYDRAULIC NODE -LINK SCHEMATIC 6-15
6.2.2 HYDRAULIC NODES 6-15
6.2.3 LINKS 6-19
6.3 MODEL CALIBRATION & VERIFICATION 6-20
6.3.1 REPETITIVE FLOOD LOSS COMPARISONS 6-21
6.3.2 FEMA FLOOD PLAIN COMPARISONS 6-26
6.3.3 KNOWN FLOODING AREA COMPARISONS 6-30
6.4 EXISTING CONDITIONS/BASELINE MODEL RESULTS 6-33
6.5 MODEL DEVELOPMENT CONCLUSION 6-33
7.0 IDENTIFICATION & RANKING OF PROBLEM AREAS 7-1
7.1 DERM SUB -BASIN FLOOD PROTECTION RANKING & FLOOD PROTECTION LEVEL
OF SERVICE PROCEDURES 7-1
7.2 CITY OF MIAMI SUB -BASIN FLOOD PROTECTION RANKING & FLOOD
PROTECTION LEVEL OF SERVICE PROCEDURE 7-3
7.3 QUANTIFYING METHODOLOGY FOR SUB -BASIN FLOODING SEVERITY
INDICATORS 7-5
7.4 FLOOD PROBLEM SUB -BASIN RANKING RESULTS AND FLOOD 'PROTECTION
LEVEL OF SERVICE RESULTS 7-9
7.5 FLOOD PROTECTION RANKING & LEVEL OF SERVICE CONCLUSION 7-10
8.0 EVALUATION OF FLOOD PROTECTION PROJECTS 8-1
8.1 REPRESENTATION OF STORMWATER IMPROVEMENT PROJECTS IN XP-SWMM8-1
8.2 REPRESENTATION OF STORMWATER PROJECTS IN XP.SWMM 8-2
8.2.1 NEW OR INCREASED PIPE SIZE 8-2
8.2.2 EXFILTRATION TRENCHES 8-2
8.2.3 GRAVITY INJECTION WELLS 8-4
8.14 STORMWATER PUMP STATIONS 8-5
8.3 • BASIN HYDROLOGIC AND HYDRAULIC MODEL SETUP 8-5
8.3.1 NORTH BISCAYNE BASIN 8-6
8.3.2 SOUTH BISCAYNE BASIN 8-6
8.4 SUMMARY OF RESULTS AND RANKINGS FOR CONSTRUCTION SCENARIO 8-7
8.5 PROJECTS UNDER DESIGN 8-9
8.6 SUB -BASIN RANKINGS & COMPARISONS 8-9
8.7 REPETITIVE .LOSS PROPERTIES 8-11
8.8 CONSTRUCTION MODEL SCENARIO CONCLUSION • 8-13
9.0 FUTURE IMPROVEMENT PROJECT FORMULATION 9-1
9.1 WATER QUALITY REGULATORY AND PERMITTING REQUIREMENTS 9-1
9.1.1 MIAMI-DADE COUNTY DERM (NOW PERA) 9-1
9.1.2 SOUTH FLORIDA WATER MANAGEMENT DISTRICT 9-2
9.1.3 FLORIDA DEPARTMENT OF ENVIRONMENTAL PROTECTION 9-3
.9.2 WATER QUANTITY REGULATORY AND PERMITTING REQUIREMENTS 9-3
9.2.1 CITY OF MIAMI 9-3
9.2.2 MIAMI-DADE COUNTY DERM 9-4
9.2.3 SOUTH FLORIDA WATER MANAGEMENT DISTRICT 9-4
9.2.4 FLORIDA DEPARTMENT OF TRANSPORTATION 9-5
9.2.5 FLORIDA DEPARTMENT OF ENVIRONMENTAL PROTECTION 9-5
9.2.6 MAXIMUM ALLOWABLE WATER ELEVATIONS 9-6
9.3 STORMWATER MANAGEMENT SYSTEMS 9-6
9.3.1 POSITIVE DRAINAGE WITH OUTFALLS 9-6
9.3.2 EXFILTRATION TRENCHES 9-7
9.3.3 DRY RETENTION BASINS 9-9
.__ 9.3.4 INJECTION DRAINAGE WELLS 9-9_
9.3.5 PUMP STATIONS 9-11
9.4 VOLUMETRIC ANALYSIS 9-12
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February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
9.5 FUTURE IMPROVEMENT PROJECT FORMULATION CONCLUSION 9-13
10.0 RANKED SUB -BASIN WITH PROPOSED PROJECTS 10-1
10:1 RANK #1 - SUB -BASIN SB09 10-2
10.2 RANK#2.- SUB=BASIN SB06 104
10.3 RANK#3 - SUB -BASIN SB25 10-5
10.4 RANK#4 - SUB -BASIN SB23 1D-7
10.5 RANK#5 - SUB -BASIN SB10 10-9
10.6 RANK#6 - SUB -BASIN SB04 10-11
10.7 RANK#7 - SUB -BASIN SB30 10-13
10.8 RANK#8 - SUB -BASIN SB13 10-15
10.9 RANK#9 - SUB -BASIN SB14 10-17
10.10 RANK#10 - SUB -BASIN SB34 10-19
10.11 RANK#11 - SUB -BASIN SB33 10-21
10.12 RANK #12 - SUB -BASIN SB28 10-23
10.13 RANK#13 - SUB -BASIN SB20 10-25
10.14 RANK#14 - SUB -BASIN SB18 10-27
10.15 RANK#15 - SUB -BASIN SB12 10-29
11.0 PLANNING -LEVEL COST ESTIMATES 11-1
11.1 COST ESTIMATE PROCEDURES & UNIT COSTS 11-1
11.2 COST ESTIMATE RESULTS 11-2
12.0 RANKING OF FUTURE PROJECTS & CAPITAL IMPROVEMENT PLAN 12-1
12.1 RANKING PROCEDURE & RESULTS 12-1
12.2 PHASE I & II COMBINED RANKING RESULTS 12-2
12.3 FUTURE PROJECT & CAPITAL PLAN CONCLUSION 12-3
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
TABLE 1-1 —.BASIN AND WATERSHED AREAS WITHIN THE CITY OF MIAMI 1-2
TABLE 1-2— PHASE I & PHASE II COMBINED RANKING OF SUB -BASINS.. 1-10
TABLE 2-1 — BASIN AND WATERSHED AREAS WITHIN THE CITY OF MIAMI 2-2
TABLE 3-1 BASIN AND WATERSHED AREAS WITHIN THE CITY OF MIAMI 3-19
TABLE 4-1 VERTICAL DATUM CONVERSION 4-2
TABLE'5.1— GIS STORMWATER INFRASTRUCTURE TOTALS 5-5
TABLE 5-2— SUB -BASIN NAMES & AREAS 5-11
CALCULATION EXAMPLE 6-1— EXFILTRATION TRENCH EXTRACTION EXAMPLE 6-7
TABLE 6-2—TOTAL IMPERVIOUS AREA PER LAND USE CATEGORY 6-8
TABLE 6-3 — SUB -BASIN PHYSICAL ATTRIBUTERS 6-9
TABLE 6-4 — NOTABLE HISTORICAL RAINFALL EVENTS 6-11
TABLE 6-5 — BOUNDARY CONDITIONS 6-18
TABLE 6-6— MODEL EFFICIENCY AND ERRORS 6-21
TABLE 7.1—TOP 15 BASINS FOR THE EXISTING CONDITION MODELS BASED ON THE FPSS7-10
TABLE 8-1 — PROJECT STATUS TOTALS • 8-1
CALCULATION EXAMPLE 8-2 — EXFILTRATION TRENCH EXTRACTION METHODOLOGY EXAMPLE
8-3
TABLE 8-3—TOTAL LENGTH OF EXFILTRATIONTRENCH INCORPORATED INTO EACH MODEL 8-4
CALCULATION EXAMPLE 8-4 — GRAVITY INJECTION WELL EXTRACTION METHODOLOGY
EXAMPLE 8-5
TABLE 8-5 — PUMP STATIONS WITHIN THE CITY OF MIAMI 8-5
TABLE 8-6 — MAIN PROJECT COMPONENTS INCORPORATED INTO THE NORTH BISCAYNE
MODEL 8-6
TABLE 8-7 — MAIN PROJECT COMPONENTS INCORPORATED INTO THE SOUTH BISCAYNE
MODEL 8-7
TABLE 8-8— STAGE COMPARISON - BASELINE TO CONSTRUCTION SCENARIOS (NGVD) • 8-7
TABLE 8-9 — SUB -BASINS RANKINGS AND COMPARISONS 8-10
TABLE 8-10 — SUB -BASINS WITH MAXIMUM NUMBER OF REPETITIVE LOSS PROPERTIES 8-12
TABLE 8-11 — SUB -BASINS WITH MAXIMUM NUMBER OF REPETITIVE LOSS PROPERTIES 8-13
TABLE 9.1 — SFWMD ALLOWABLE DISCHARGE RATE FORMULAS FOR BASINS WITH
RESTRICTED DISCHARGE • 9-5
CALCULATION EXAMPLE 9.2— EXFILTRATION TRENCH EXTRACTION VOLUME CALCULATION
EXAMPLE 9-8'
CALCULATION EXAMPLE 9-3 —RETENTION BASIN VOLUME CALCULATION EXAMPLE 9-9
CALCULATION EXAMPLE 9-4— INJECTION WELL VOLUME CALCULATION EXAMPLE 9-11
TABLE 10-1 — TOP 15 RANKED SUB -BASINS 10-1
TABLE 10-2— SUB -BASIN SB09 STAGE REDUCTION ESTIMATES 10-3
TABLE 10-3 - SUB -BASIN SB09 PROPOSED STORMWATER MANAGEMENT SYSTEM
COMPONENTS .10-3
TABLE 10-4— SUB -BASIN SB06 STAGE REDUCTION ESTIMATES 10-5
TABLE 10-5 — SUB -BASIN SB06 PROPOSED STORMWATER MANAGEMENT SYSTEM
COMPONENTS 10-5
TABLE 10-6 — SUB -BASIN SB25 STAGE REDUCTION ESTIMATES 10-7
TABLE 10-7— SUB -BASIN SB25 PROPOSED STORMWATER MANAGEMENT SYSTEM
COMPONENTS 10-7
TABLE 10-8 — SUB -BASIN SB23 STAGE REDUCTION ESTIMATES '10-9
TABLE 10-9 — SUB -BASIN SB23 PROPOSED STORMWATER MANAGEMENT SYSTEM
COMPONENTS 10-9
TABLE 10-10 — SUB -BASIN SB10 STAGE REDUCTION ESTIMATES 10-11
TABLE 10-11 — SUB -BASIN SB10 PROPOSED STORMWATER MANAGEMENT SYSTEM
COMPONENTS 10-11
TABLE 10-12 =.SUB -BASIN SB04 STAGE REDUCTION ESTIMATES 110-13
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February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
TABLE 10.13 — SUB -BASIN SBD4 PROPOSED STORMWATER MANAGEMENT SYSTEM
COMPONENTS 10-13
TABLE 10-14— SUB -BASIN SB30 STAGE REDUCTION ESTIMATES 10-15
TABLE 10-15— SUB BASIN SB30 PROPOSED STORMWATER MANAGEMENT SYSTEM
COMPONENTS 10-15
TABLE 10-16—SUB-BASIN SB13 STAGE REDUCTION ESTIMATES 10-17
TABLE 10-17 — SUB -BASIN SB13 PROPOSED STORMWATER MANAGEMENT SYSTEM
COMPONENTS 10-17
TABLE 10-18 — SUB -BASIN SB14 STAGE REDUCTION ESTIMATES 10.19
TABLE 10-19 — SUB -BASIN S614 PROPOSED STORMWATER MANAGEMENT SYSTEM
COMPONENTS 10-19
TABLE 1 D 20 — SUB -BASIN SB34 STAGE REDUCTION ESTIMATES 10-21
TABLE 10-21— SUB -BASIN SB34 PROPOSED STORMWATER MANAGEMENT SYSTEM
COMPONENTS 10-21
TABLE 10-22 — SUB -BASIN S633 STAGE REDUCTION ESTIMATES 10-23
TABLE 10-23 — SUB -BASIN SB33 PROPOSED STORMWATER MANAGEMENT SYSTEM
COMPONENTS 10-23
TABLE 10-24 — SUB -BASIN SB28 STAGE REDUCTION ESTIMATES 10-25
TABLE -10-25— SUB -BASIN SB28 PROPOSED STORMWATER MANAGEMENT SYSTEM
COMPONENTS 10-25
TABLE 10-26— SUB -BASIN SB20 STAGE REDUCTION ESTIMATES 10-27
TABLE 10-27— SUB -BASIN SB20 PROPOSED STORMWATER MANAGEMENT SYSTEM
COMPONENTS 10-27
TABLE '10-28 — SUB -BASIN SB18 STAGE REDUCTION ESTIMATES 10-29
TABLE 10-29— SUB -BASIN SB18 PROPOSED STORMWATER MANAGEMENT SYSTEM
COMPONENTS 10-29
TABLE 10-30— SUB -BASIN SB12 STAGE REDUCTION ESTIMATES 10-31
TABLE 10-31 — SUB -BASIN SB12 PROPOSED STORMWATER MANAGEMENT SYSTEM
COMPONENTS 10-31
TABLE 11-1— PLANNING -LEVEL CONSTRUCTION COSTS PER SUB -BASIN 11-2
TABLE '12-1 — REVISED RANKING OF PHASE II SUB -BASINS 12-2
TABLE '12-2— PHASE I & PHASE II COMBINED RANKING OF SUB -BASINS 12-3
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February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
FIGURE 1-1 — BASINS AND WATERSHEDS WITHIN THE CITY OF MIAMI 1=1
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 WITHINTHE CITY OF MIAMI 3-8
FIGURE 3-7— NOAA CO-OPS ODIN DATA ACCESS SITE 3-9
FIGURE 3-8 NOAA GIS DATA SITE 3-10
FIGURE 3-9 — USGS GROUNDWATER WELL DATA SITE 3-11
FIGURE 3-10— USDA'S GEOSPTIAL DATA GATEWAY SITE 3-12
FIGURE 3-11 — ONE -DAY RAINFALL FREQUENCY ANALYSIS AT MIA 3-18
FIGURE 3-12 — THREE-DAY RAINFALL FREQUENCY ANALYSIS AT MIA 3-18
FIGURE 3-13 — LOCATION OF DBHYDRO GAUGE STATIONS 3-20
FIGURE•4-1 — LIDAR POINT DISTRIBUTION .4-2
FIGURE 4-2— NAVD 88 TO NGVD 29 DATUM SHIFT 4-3
FIGURE4-3—TIN REPRESENTATION 4-4
FIGURE 4-4—TIN - GAP INTERPOLATION 4-5
FIGURE•4-5 — RASTER DATASET REPRESENTATION 4-6
FIGURE 4-6 — CITY OF MIAMI DEM 4-7
FIGURE 5-1 — CITY OF MIAMI SUB -BASIN DELINEATION 5-1
FIGURE 5-2 — CITY OF MIAMI SUB -BASIN DELINEATION - WITH DTM 5-2
FIGURE 5-3 — COASTAL BOUNDARY IN SUB -BASIN DELINEATION 5-3
FIGURE 5-4 — INFRASTRUCTURE ALIGNMENT 5-4
FIGURE 5-5— CITY OF MIAMI DEM 5-6
FIGURE 5-6 — DELINEATED SUB -BASINS BASED ON TOPOGRAPHY 5-7
FIGURE 5-7 — PHASE I AND PHASE II SUB -BASIN LIMITS & OVERLAP 5-8
FIGURE 5-8— PHASE II SUB -BASIN LIMITS - NORTH BASIN 5-9
FIGURE 5-9 — PHASE II SUB -BASIN LIMITS - SOUTH BASIN 5-10
FIGURE 6-1 — XP-SWMM HORTON METHOD INPUT PARAMETERS 6-5
FIGURE 6-2— AREA ATTRIBUTED TO AN EXFILTRATION TRENCH LENGTH 6-6
FIGURE 6-3— 1999 GROUNDWATER LEVELS FOR STATIONS F-45 AND F-179 6-13
FIGURE 6-4 — 2000 GROUNDWATER LEVELS FOR STATIONS F-45 AND F-179 6-13
FIGURE 6-5— HURRICANE IRENE TIDAL DATA GRAPH 6-17
FIGURE 6-6 — NO -NAME STORM TIDAL DATA GRAPH 6-17
FIGURE 6-7 — 5 AND 100-YEAR DESIGN STORM EVENT TIDAL DATA GRAPH 6-18
FIGURE 6-8— SAMPLE CROSS SECTION INPUT FOR OVERLAND WEIR 6-20
FIGURE 6-9 - REPETITIVE LOSSES COMPARED TO HURRICANE IRENE & "NO -NAME" STORM
SIMULATED FLOOD PLAINS 6-23
FIGURE 6-10 — REPETITIVE LOSSES COMPARED TO HURRICANE IRENE & "NO -NAME" STORM
SIMULATED FLOOD PLAINS 6-24
FIGURE 6-11 — REPETITIVE LOSSES COMPARED TO HURRICANE IRENE & "NO -NAME" STORM
SIMULATED FLOOD PLAINS 6-25
FIGURE 6-12 — FEMA FLOOD PLAINS AND 100-YEAR STORM SIMULATED FLOOD PLAINS. 6-27
FIGURE 6-13 — FEMA FLOOD PLAINS AND 100-YEAR STORM SIMULATED FLOOD PLAINS. 6-28
FIGURE 6-14 — FEMA FLOOD PLAINS AND 100-YEAR STORM SIMULATED FLOOD PLAINS. 6-29
FIGURE 6-15 — CITY RECORDED .FLOOD COMPLAINT DATA AND 5-YEAR STORM .SIMULATED
FLOOD PLAINS. 6-31
FIGURE 6-16 — CITY RECORDED FLOOD COMPLAIN DATA AND 5-YEAR STORM SIMULATED
FLOOD PLAINS. 6-32
FIGURE7-1 —RASTER BASED DEM 7-6
FIGURE 7-2 — ROADWAYS LINES TO POINTS 7-6
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February.2012 City of Miami
Phase II - Stormwater Management Master Plan Final
FIGURE 7-3 — PROPERTY POLYGONS TO POINTS 7-7
FIGURE 7-4— DEM TO POINTS 7-8
FIGURE 7-5 — SAMPLE OF FLOOD PLAIN MAPPING RESULTS 7-9
FIGURE 8-1— AREA ATTRIBUTED TO AN EXFILTRATION TRENCH LENGTH 8-3
FIGURE 9-1 —TYPICAL EXFILTRATION TRENCH SECTIONS 9-8
FIGURE 9-2 —TYPICAL INJECTION DRAINAGE WELL 9-10
FIGURE 9-3 — TYPICAL STORMWATER PUMP STATION PLAN 9-12
FIGURE 10-1— SUB -BASIN SB09 TOPOGRAPHIC TRENDS & EXISTING STORMWATER
INFRASTRUCTURE 10-2
FIGURE 10-2 — SUB -BASIN SBD6 TOPOGRAPHIC TRENDS & EXISTING STORMWATER
INFRASTRUCTURE 10-4
FIGURE 10-3— SUB -BASIN SB25TTOPOGRAPHIC TRENDS & EXISTING STORMWATER
INFRASTRUCTURE 10-6
FIGURE 10-4 — SUB -BASIN SB23 TOPOGRAPHIC TRENDS & EXISTING STORMWATER
INFRASTRUCTURE 10-8
FIGURE 10-5— SUB -BASIN SB10 TOPOGRAPHIC TRENDS & EXISTING STORMWATER
INFRASTRUCTURE 10-10
FIGURE 10-6 — SUB -BASIN SB04 TOPOGRAPHIC TRENDS & EXISTING STORMWATER
INFRASTRUCTURE 10-12
FIGURE 10-7— SUB -BASIN SB30 TOPOGRAPHIC TRENDS & EXISTING STORMWATER
INFRASTRUCTURE 10-14
FIGURE 10-8 — SUB -BASIN SB13 TOPOGRAPHIC TRENDS & EXISTING STORMWATER
INFRASTRUCTURE 10-16
FIGURE 10-9 — SUB -BASIN SB14 TOPOGRAPHIC TRENDS & EXISTING STORMWATER
INFRASTRUCTURE 10-18
FIGURE 10-10 — SUB -BASIN SB34 TOPOGRAPHIC TRENDS & EXISTING STORMWATER
INFRASTRUCTURE 10-20
FIGURE 10-11 — SUB -BASIN SB33 TOPOGRAPHIC TRENDS & EXISTING STORMWATER
INFRASTRUCTURE 10-22
FIGURE 10-12 — SUB -BASIN S628 TOPOGRAPHIC 'TRENDS & EXISTING STORMWATER
INFRASTRUCTURE 10-24
FIGURE 10-13 — SUB -.BASIN SB20 TOPOGRAPHIC TRENDS & EXISTING STORMWATER
INFRASTRUCTURE 10-26
FIGURE 10-14 — SUB -BASIN SB18 TOPOGRAPHIC TRENDS & EXISTING STORMWATER
INFRASTRUCTURE 10-28
FIGURE 10-15— SUB -BASIN SB1.2 TOPOGRAPHIC TRENDS & EXISTING STORMWATER
INFRASTRUCTURE 10-30
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February.2012
City of Miami
Phase II - Stormwater Management Master Plan Final
ATTACHMENT A
ATTACHMENT B
ATTACHMENT C
ATTACHMENT D
*ATTACHMENT E
*ATTACHMENT F
*ATTACHMENT G
*ATTACHMENT H
*ATTACHMENT I
ATTACHMENT J
ATTACHMENT K —
ATTACHMENT L —
ATTACHMENT M —
ATTACHMENT N —
ATTACHMENT 0 —
ATTACHMENT P —
ATTACHMENT
ATTACHMENT
ATTACHMENT
ATTACHMENT
ATTACHMENT
O—
R —
5 —
T —
U —
ATTACHMENT V —
ATTACHMENT W —
ATTACHMENT X —
ATTACHMENT Y —
at me
— CITY OF MIAMI.DATA CATALOG
— MIAMI DADE COUNTY DATA CATALOG
— TOPOGRAPHIC MAPS
— SUB -BASIN DELINEATION MAPS
— XP-SWMM MODEL NODE -LINK SCHEMATICS
— HURRICANE IRENEXP-SWMM INPUT/OUTPUT REPORTS
— NO -NAME STORM XP-SWMM INPUT/OUTPUT REPORTS
— 5-YEAR,.24-HOUR DESIGN STORM XP-SWMM INPUT/OUTPUT REPORTS
— 100-YEAR, 72-HOUR DESIGN STORM XP-SWMM INPUT/OUTPUT REPORTS
— FLOOD PLAIN MAPS
SUB -BASIN RANKING TABLES .
MAP OF MODEL SUB -BASINS SHOWING FPSS RANKINGS
FLOOD PLAIN MAPS - DIGITAL GIS RASTER
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
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
PLANINNG LEVEL CONSTRUCTION COST ESTIMATES
RANKED PLANNING -LEVEL CONSTRUCTION COST ESTIMATES
•
*Attachments provided diaitally due to size and number of sheets,
viii
February.2012
City of Miami
Phase II - Stormwater Management Master Plan Final
1.1 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 coastal basins or in 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 1.1 shows the City limits and the extent of the major basins within
the City, and Table 1-1 summarizes the area of these basins and total area located
within the mainland portion of the City.
Legend
D City of Miami Limits
Major Basins in City of Miami
C-3
iOA C-4
C-S
C-6
MI C-7
KO Biscayne North
Biscayne South
iu? ; Island
Basiniaoundaries (DERM)
Figure 1-1 — Basins and Watersheds within the City of Miami
1-1
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
Table 1-1 -Basin and Watershed Areas within the City of Miami
k`3� f YY-�ig Y 4$
,A .b ,!e,, k
t . siri/:Watershed riE
}�+ a'• fk � 2 y ' rt�
4��.LL ,u z#b !W'✓i G' i .
� Tota�IrBas q Area g �=
Sguar:eiMiies (SM).
.otAIPAreatwithi6, the Mamiand1
4 •�v ti. A qt hy'� Y.* , t�. •�••
t Areasrofrthe Ctt��+�of#Mlam fi .
X4 s. ,5qua;reMiles(SMpi„ �:
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, :
`.....::4271 60
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 be able to meet the requisites 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. By improving the CRS
rating from a Class 8 to Class 4, the City's residents could potentially 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, th.e Miami -Dade County
Department of Environmental Resources Management (DERM - recently changed to
Department of Permitting, Environment and Regulatory Affairs or PERA) 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. Both phases of the Stormwater Management Master Plan
(SWMMP) update process will address mainland areas of the City and does 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. They also address flood protection levels of
service of primary drainage systems such as large conveyance storm drain systems
and canals. These Stormwater Master Plan updates does not address secondary
1-2
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final •
drainage systems and minor localized flooding. In addition, Phase I and. Phase II does
not address -the water quality of stormwater dischargesfrom the City to receiving water
bodies. However, the computer modeling..tools that were 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.
Phase I of the update process included the mainland areas of the City encompassed
within the C-3, C-4, C-5, C-6 and C-7 basins (approximately .21 SM). Phase I was
developed using the existing hydrologic/hydraulic models and information developed by
DERM for these basins. This data was used to establish the City's current flood
protection level of service and to evaluate the flood protection effectiveness of current
and future City stormwater management projects. The findings from Phase I were
summarized in the City of Miami Phase I Stormwater Management Master Plan Report
(January 2010 - under separate cover).
Phase II of the Stormwater Master Plan update process includes 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, this Phase II update required the development, calibration, and verification
(depending on data availability) of 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 used the previously described procedures established by DERM and
approved by FEMA and FIMA to develop these models and perform the required
analyses. The findings of Phase II are summarized in this Stormwater Management
Master Plan Report which includes a capital improvement plan that will be inclusive of
the capital improvement projects and relevant data from Phase I and Phase II. This
comprehensive capital improvement plan will help guide the City in implementing future
projects in a systematic approach that will maximize flood protection within the limited
available funding for all mainland portions of the City of Miami.
Once Phase II of the Stormwater Management Master Plans is adopted by the City
Commission, the City will then be able to apply for an improved NFIP CRS classification
and be able to proceed with additional credits which are dependent on the completion of
the Stormwater Management Master Plan as a prerequisite.
To perform Phase II of 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 January 6, .2008 (Contract No. 06-07-019) to complete
Phase II of the SWMMP. Phase II of the SWMMP was subdivided into nine
tasks/technical memorandums with the final task consisting of the preparation of the
final Phase II SWMMP. The nine tasks were developed as follows:
• Technical Memorandum No. 1 — Data Collection and Evaluation
• Technical Memorandum No. 2 — Development of Digital Terrain Model
• Technical Memorandum No. 3 — Delineation of Sub -basins
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February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
Technical Memorandum No. 4 — Hydrologic and Hydraulic Modeling of Existing
and Future Condition Land Uses without City
Flood Protection .Projects
Technical Memorandum No. 5 — Identification and Ranking of Problem Areas
'• Technical Memorandum No. 6 — Hydrologic and Hydraulic Modeling of Existing
and Future Condition Land Uses with City
Flood Protection Projects Completed and
Under Construction
Technical Memorandum No. 7— Hydrologic and Hydraulic Modeling of Existing
and Future Condition Land Uses with City
Flood Protection Projects Under Design
Technical Memorandum No. 8 Identification, Ranking and Prioritizing Future
City Flood Protection Projects and Flood
Protection Projects Under Design
Technical Memorandum No. 9 - City Stormwater Infrastructure Atlas Update
(Under Separate Cover)
Phase II — Stormwater Management Master Plan Report
The results and findings of each primary task were summarized in 'task specific
technical memorandums. The results and findings of each of the primary tasks
prepared as part of the Phase II SWMMP are detailed in the following subsections.
1.2 .Data Collection and Evaluation
As a part of the Data Collection and Evaluation 'task, readily available data was
collected, specifically within the DA-1/South Biscayne Bay and North Biscayne Bay
Basins. 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: -
•
0
•
•
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 (NRCS)
Federal Emergency Management Agency (FEMA) - National Flood. Insurance
Program
The collected data was cataloged, evaluated, and utilized as necessary to support the
analyses and preparation of the Stormwater Management Master Plan Report for
Phase II. Water quality data was stored for potential future use, but was not processed
or evaluated for this project. Topographic, geotechnical, or other specific surveys were
not included in the scope of work. Sufficient data was collected to proceed with the
1-4
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
development of this stormwater master plan update. This subsection is detailed further
in Section 3.0.
1.3 Development of Digital Terrain Model
Under the Development of the Digital Terrain Model (DTM) task, a three-dimensional
topographic terrain model of the City of Miami was developed using the topographic
Light Detection And Ranging (LiDAR) .data collected from Miami Dade County as a part
of Data Collection and Evaluation task.
The topographic digital terrain model was developed using relatively accurate and
representative LiDAR data sets of the City of Miami. The density of the points collected
by Florida Division of Emergency Management (FDEM) and the filtering of the datasets
for structures and vegetation resulted in a topographic model that is representative of
the bare -earth nature of the region. These LiDAR points also provided accurate
interpretations of the City's topography with a relatively small average elevation error of
0.6 feet which is sufficient for planning -level studies.
The resulting raster DTM with 25 foot by 25 foot cell resolution provides a way of
accurately determining sub -basin boundaries within the City as well as a way of
calculating stage -area relationships for all areas within the City. Additionally, all of the
City's major topographic features can be easily distinguished when viewed dynamically
in GIS or in properly symbolized maps. Major roadways, local roads, and water bodies
are all visible from the raster based DTM.
The DTM will be provided in both the National Geodetic Vertical Datum of 1929 (NGVD
29) vertical datum and the City of Miami vertical datum. The DTM covers the entire
limits of the City of Miami. This subsection is detailed further in Section 4.0.
1.4 Sub -basin Delineation
The purpose of the Delineation of Sub -basins task was to detail the efforts undertaken
in delineating the drainage sub -basins for the Phase II limits of the City of Miami
Stormwater Master Plan. The sub -basin delineation was developed using the LiDAR
based DEM developed as well as historical sub -basin delineations and infrastructure
data from the City.
The sub -basin delineation developed for Phase II of the City of Miami Stormwater
Management Master Plan update was developed using the best available topographic
and infrastructure data. Although the City was in possession of an existing sub -basin
delineation, this delineation was a number of years old and appeared to not take into
account the detailed topographic elevations that were available for this study. LiDAR
data, with a relative stated horizontal accuracy of ±3.8-feet and a vertical accuracy of
±0.6-feet, is an excellent source for planning -level topographic elevations and provides
a clear indication of the high and low areas within the City. Additionally, the City's GIS
files showing the location of outfalls, primary conveyance systems, and extent of
stormwater infrastructure coverage, also facilitate the delineation process.
1-5
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
The detailed nature of the data available for this SWMMP update .allowed for a more
precise delineation of the City's hydraulic basins. Although attempts were made to
maintain uniformity between the .sub -basin sizes for the .purposes of. the ranking tasks,
the nature of the systems and topography supersede this need and were addressed in
.the ranking procedure as was done for Phase I of this SWMMP update. This
subsection is detailed further in Section 5.0.
1.5 Existing Conditions Model Development
For the Hydrologic and Hydraulic Modeling of Existing and Future Condition Land Uses
without City Flood Protection Projects task, existing conditions hydraulic and hydrologic
models were developed for the Phase II limits of the City of Miami Stormwater Master
Plan. The hydraulic and hydrologic models were developed using the XP-SWMM
model platform, applying -the guidance and methodologies implemented by-the-DERM
stormwater master planning initiatives completed for the C-3, C-4, C-5, C-6, and C-7
Canal Basin models and supporting documentation. These models were used .to
establish an existing or baseline flood protection level of service for the South Biscayne
Basin (SBB) and North Biscayne Basin (NBB).
DERM established a solid basis for the concepts and methodologies needed for the
development of a complete and quantifiably representative hydrologic/hydraulic model.
Methods for calculating stage -areas and defining hydrologic parameters typical to South
Florida, as well as typical assumptions regarding urban stormwater management
systems, were all well documented in the various Miami Dade County Basin SWMMP
reports. These methods and concepts were carried forward to the City SWMMP model
development process, whenever possible and/or viable. The methodologies were
revised slightly to account for a lack of available calibration data and due to specific land
and hydrologic features in the City of Miami.
Although calibration of the XP-SWMM models was performed using anecdotal data due
to the absence of stage, flow, or runoff volume data for canals, streams, rivers, or lakes
within the City's two coastal basins, the results appeared to generally correspond with
expected results within the sub -basins. Comparisons to the FEMA flood plains, FEMA
repetitive property loss database, and to the City collected complaint data showed areas
where good correlation to the prelirninary flood plains existed.
The resulting models developed for this project were both stable with regards to the
internal calculations performed by XP-SWMM as well as justifiable based on the
anecdotal calibration process undertaken. The results obtained from these models
provided a relatively representative and detailed synopsis of the conditions present
within the City. The models also provided for the existing baseline condition for all
comparisons for the future condition models as well as for the development of future
planning -level projects to be defined in later tasks. Additionally, these models will
__provide _th.e_City_with_tsefu.lp.fanning-lev..l_tooIs_lhal_will_aidJhe CJtyJb_defin_future
projects and potential future expenditures, particularly for the development of the capital
improvement plan. This subsection is detailed further in Section 6.0.
1-6
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
1.6 Identification and Ranking of Problem Areas
The. Identification .and .Ranking of Problem Areas task documented the identification and
ranking of existing stormwater management problem areas in the City located within the
North and South Biscayne Basins (NBB and SBB, respectively) and established current
flood protection levels of service for all sub -basins within Phase II.
DERM 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 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.
_this ._methodology,. the._ranking .of flooding _problem ._areas ._was_relatedio__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
FP.LOS 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 were modified for both Phase I and II of
this SWMMP update due to a reduction in the number of design storm events used .by
the City 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.
With regards to the FPLOS, few sub -basins were scored a "B". The vast majority of the
sub -basins scored either "C", "D", or "E". This was expected given the extent of the 5-
and 100-year flood plains derived from the DEM and the XP-SWMM result data.
Additionally, the ranking procedure showed that the 'top 15 ranked sub -basins resided in
the South Biscayne basin. This can be attributed to both the extent of flooding in these
sub -basins' and the overall size of the contributing area to these sub -basins. This
subsection is detailed further in Section 7.0.
1.7 Evaluation of Flood Protection Projects
In the Hydrologic and Hydraulic Modeling of Existing and Future Condition Land Uses
with City Flood Protection Projects Completed, Under Construction, and Under Design
task, projects were evaluated to assess the flood protection benefits that were realized
by the stormwater improvement or flood protection projects completed, under .
construction, and under design by the City within the North and South Biscayne basins.
The City of Miami constructed or was in the process of constructing a total of 10
stormwater improvement projects within the North and South Biscayne basins. The
construction projects incorporated into the Construction Scenario models were
categorized into their main drainage components.
1-7
February 2012 • City of Miami
Phase II - Stormwater Management Master Plan Final
Internal 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 Biscayne Bay, were represented. The primary drainage
components included in these projects were comprised of:
-• Gravity. drainage systems with outfalls,
. Exfiltration trenches,
• Drainage wells, and
Stormwater pump stations.
The major components of these drainage systems were represented in the XP-SWMM
models by either including the location and size of the pertinent drainage component or
by an -equivalent rainfall extraction representative of the -amount -of -runoff extraction from -----
overland flow to the respective sub -basin. This subsection is detailed further in Section
8.0.
1.8 Future Improvement Project Formulation
The purpose of this task was to evaluate the stormwater infrastructure needs for the top
15 ranked sub -basins determined in Section 8.0 and to devise flood protection projects
for each of the top 15 sub -basins in order to improve the flood protection level of service
for these critically low areas. 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.
Projects were then formulated and the projects were evaluated based on reducing the
depth of flooding and identified the total excess volume to be mitigated by these
projects. Stormwater management systems which included exfiltration trenches, pump
stations, and injection wells, 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 ina 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.
Each sub -basin was evaluated forthe 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 for the 100-year, 72-
hour event.
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. Cost for
1-8
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
these proposed systems were also evaluated and 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. These drivingfactors resulted in
the majority of the construction cost for these projects being around .$2,000,000. This
subsection is detailed further in Section.9.0.
1.9 Ranked Sub -Basins with Proposed Projects
Future projects were devised for 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.
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.
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.
This subsection is detailed further in Section 10.0.
1.10 Planning -Level Cost Estimates
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.
These driving factors resulted in the majority of the construction cost for these projects
being around $2,000,000. Some projects such as pump stations with drainage wells
may exceed this total cost.
In addition to the planning -level construction direct cost subtotal shown for each sub -
basin, maintenance of traffic, mobilization, CIP management, construction
management, permits, survey, design, and construction contingency were also been
included in the planning -level construction cost total. This subsection is detailed further
in Section 11.0.
1.1.1 Ranking of Future Projects & Capital .Improvement Plan
The ranking procedure was based on two components that 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 numbed
properties affected and the percentage of the properties experiencing a benefit from the
proposed improvements.
1-9
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
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 that affect the highest number of properties at
the lowest cost per structure.
With these components quantified, the sub -basins were then ranked by the calculated
Importance Factor and then by the Cost per Flooded Property Removed from Flood
Plain. 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.
A combined ranking was then prepared in accordance with the recommendations of
Phase I of this SWMMP. The combined ranking results are inclusive of all of the areas
the City and .prioritize all of the proposed improvements, by_sub-basin.
The revised ranking was solely based on the procedure described previously where the
sub -basins were ranked by the Importance Factor first and then by the Cost per
Flooded Property Removed -from Flood Plain. The ranking identifies which sub -basin
improvements provide the highest return in terms of flood protection at the lowest cost.
The final revised ranking is presented in Table 1-2.
This ranking is intended as a guidance tool to be used by the City to internally prioritize
future projects based on the findings of both Phase I and Phase II of this Stormwater
Management Master Plan. Additionally, the totals in these cost estimates are not
defined as commitments to expenditures by the City for any time period and are only
presented in order to provide the City with a ' magnitude of cost for the proposed
improvements.
Table 1-2 — Phase I & Phase II Combined Ranking of Sub -basins
- y..S Uti-,�t �+
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tBasin
Rank
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1-10
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
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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- determir►ing factor in the decision making process -of -how, —what; where
--
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 and projects 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. This subsection is detailed further in Section 12.0.
1.12 City Stormwater Infrastructure Atlas Update
With the data collected as a part of the data collection task, GIS shapefiles were
developed in order to update the City's existing GIS .based stormwater infrastructure
files. The new infrastructure data was digitized from the existing plans and electronic
files provided. 24 projects were chosen by the City for inclusion into the updates which
included both Phase I and Phase II projects collected as a part of this SWMMP.
Where available, the following data was populated in the GIS shapefile database fields:
Structure type
• Structure dimensions
Structure Inverts
-• Pipe material
• French drain locations
Upstream/downstream-pipe inverts
• Estimated pipe length
Pump station size
February 2012 City of Miami
Phase II - StormWater Management Master Plan Final
The existing GIS provided by the City did not include fields -for properly populating this
data and it was determined that developing new shapefiles with this fields would provide
a greater.benefit to the City than to continue,with appending the existing GIS shapefiles.
A revised sub -basin delineation GIS shapefile for the City was also provided in addition
to the infrastructure data provided. With the new shapefiles, the City will be able to
populate area specific stormwater atlas sheets which are more representative to
existing conditions. These shapefiles and supporting documentation were provided
under separate cover.
1-12
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
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 coastal basins or in 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 1•=1 shows the City limits and the extent of the major basins within
the City, and Table 1-1 summarizes -the area of these basins and total area located
within the mainland portion of the City.
Legend_---
City of Miami.Limits
Major Basins in City of Miami
its C 3
c-a
t "« GS
C-6
C-7
--.
Biscayne North
ISE Biscayne South
Island
Figure 2-1 — Basins and Watersheds within the City of Miami
2-1
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
Table.2-1 — Basin and Watershed Areas within the City of Miami
r,
J -K 2 xC _
k - YES t
Yf,...: iK
Basin/Watershed
y� k � '
y L .,. r'..ei l.,,i 3 p k"` W+iY f t Y
dR l
a{, _ 'otal BasmrArea l
iF E t �, �i 1�
oaf..,, • Squaye Milesa(SM) j �,,;
Total;Areaxw►tiiii the '47jp: antl
9 i ,,
V
} reas of the C► .* cl lM►am►
ti °S -�:. •. Y •''h .Y is
" 5'quare Miles :
C-3
16:77
2:75
C-4
79.98
3.32
C5
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
TOT,4L :;
; 271 60 -
...:.
' .
34 02 . . _
TheCity last prepared .a .Stormwater Drainage .Master. _Plan in._1986 _for_ihe .mainland__._
areas of the City, which excluded the barrier islands located within the City's limits. In
order for the City to be able to meet the requisites 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. By improving the CRS
rating from a Class 8 to Class 4, the City's residents could potentially 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 - recently changed to
Department of Permitting, Environment and Regulatory Affairs or PERA) 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. Both phases of the Stormwater Management Master Plan
(SWMMP) update process will address mainland areas of the City and does not include
h.ather_islahrLdrainage.systems_su.ch_as the Pn.ri_of_/Jiami_area,_ inginia_Sey,anrl_ofher
areas not part of the City's mainland areas. They also address flood protection levels of
service of primary drainage systems such as large conveyance storm drain systems
and canals. These Stormwater Master Plan updates does not address secondary
2-2
February2012 City of Miami
Phase II - Stormwater Management Master Plan Final
drainage systems and minor localized flooding. In addition, Phase I and Phase II does
not address the water quality of stormwater discharges from the City to receiving water
bodies. However, the computer mo.deling_toois that..were implemented in.._P.h.ase 1- 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.
Phase I of the update process included the mainland areas of the City encompassed
within the C-3, C-4, C-5, C-6 and C-7 basins (approximately 21 SM). Phase I was
developed using the existing hydrologic/hydraulic models and information developed by
DERM for these basins. This data was used to establish the City's current flood
protection level of service and to evaluate the flood protection effectiveness of current
and future City stormwater management projects. The findings from Phase I were
summarized -in the City -of Miami Phase I .Stormwater-Management Master -Plan
(January 2010 - under separate cover).
Phase II of the Stormwater Master Plan update process includes 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, this Phase 11 update required the development, calibration, and verification
(depending on data availability) of 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 used the previously described procedures established by DERM and
approved by FEMA and FIMA to develop these models and perform the required
analyses. The findings of Phase II are summarized in this Stormwater Management
Master Plan Report which includes a capital improvement plan that will be inclusive of
the capital improvement projects and relevant data from Phase I and Phase II. This
comprehensive capital improvement plan will help guide the City in implementing future
projects in a systematic approach that will maximize flood protection within the limited
available fundingfor all mainland portions of the City of Miami.
Once Phase II of the Stormwater Management Master Plans is adopted by the City
Commission, the City will then be able to apply for an improved NFIP CRS classification
and be able to proceed with additional credits which.are dependent on the completion of
the Stormwater Management Master Plan as a prerequisite.
To perform Phase II of 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 January 6, 2008 (Contract No. 06-07-019) to complete
Phase II of the SWMMP. Phase II of the SWMMP was subdivided into nine
tasks/technical memorandums with the final task consisting of the preparation of the
final Phase II SWMMP. The nine tasks were developed as follows:
T-echnical-Memorandum-No-1--Data-Collection-and-E—valuation
o Technical Memorandum No. 2 — Development of Digital Terrain Model
o Technical Memorandum No. 3 — Delineation of Sub -basins
2-3
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
Technical Memorandum No. 4 —
• Technical Memorandum No. 5 —
Technical Memorandum No. 6 —
Technical Memorandum No. 7 —
Technical Memorandum No. 8 —
• Technical Memorandum No. 9 —
Hydrologic and Hydraulic Modeling of Existing
and Future Condition Land Uses without City
Flood Protection Projects
Identification and Ranking of Problem Areas
Hydrologic and Hydraulic Modeling of Existing
and Future Condition Land Uses with City
Flood Protection Projects Completed and
Under Construction
Hydrologic and Hydraulic Modeling of Existing
and Future Condition Land Uses with City
Flood Protection Projects Under Design
Identification, Ranking and Prioritizing Future
City Flood Protection Projects and Flood
Protection Projects Under Design
City Stormwater Infrastructure Atlas Update
(Under Separate Cover)
.• Phase II — Stormwater Management Master Plan Report
The results and findings of each primary task were summarized in task specific
technical memorandums. The results and findings of each of the primary tasks
prepared as part of the Phase II SWMMP are detailed in the following subsections.
2-4
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
•
The data collection task required collecting data from the various entities with
jurisdiction or that maintain data within and around 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 (USAGE)
-• United States Geological Survey(USGS)
Natural Resources Conservation Service (NRCS)
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 II 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
c. Land use (existing and future)
d. Soil types
e. Storm Sewer systems (wells, exfiltration trenches, pipes, outfalls, etc.)
1. 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
3-1
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
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 Ran
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 logs
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
17. Hi -resolution aerial imagery
Data collected from other entities was based on research of available web -data portals
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. 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, Of the 61 projects, data were 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. Additionally, the City provided flood complaint data
collected- s ince-2005-and-located-.by-street-add ress-which-identifies-localized--areas
showing recurring flood problems; scans of the City's record grade atlas sheets;
scanned sanitary sewer maps; and bid tabulations and probable construction costs for
various projects.
3-2
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
The City is also in the process of providing hi -resolution aerial imagery which will be
used to locate and digitize • improvements to the City's stormwater infrastructure
shapefiles as well as to identify key features within the City without the need for site
visits.
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-1, 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 and were available through the Florida Division of Emergency
Management (FDEM - http://floridadisaster.orq/qis/LIDAR/index.htm).
#JL6 nlcad 'alazTltn;fJTgfac```,.,r. ��4-ir ka:.kr� a � u,;..:i.. 'val:*41 f ! ` t aoffig
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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 2D0-9—SfD aerial images of
the County. The majority of Miami -Dade County's GIS data is also accessible via the
web, at the following location:
3-3
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
• Miami -Dade County GIS data portal
o http://arcgisinter.miamidade.00v/GISSelfServices/GeooraphicData/MDGe
ooraphicData.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 Data from Other Sources
In addition to the main data contributions from the City of Miami and Miami -Dade
County, other sources of information were accessed to help support the development of
the Phase II Stormwater Management Master Plan Reports. The following subsections
provide a description of the entity and applicable data collected to support development
of Phase I and II of the City's SWMMP.
3.3.1 South Florida Water Management District (SFWMD)
The SFWMD maintains an extensive water resources database, titled DBHYDRO,
which includes hydrologic, rrieteorological, 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
• 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. Rainfall data was collected and
analyzed from_DB.HY:DRO_for_the_long term station. at_Miami _International Airport.
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:
• GIS Data distribution site:
o http://my.sfwmd.gov/gisapps/sfwmdxwebdc/.
• DBHYDRO monitoring station shapefile:
o http://my.sfwmd.gov/gisapps/sfwmdxwebdc/dataview.asp?query=unq_id=
1588
Jo:toContaulls➢sn"nl
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
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DBHYDRO is the South Florida Water Management District's corporate environmental database which
stores hydrologic, meteorologic, hydrogeologic and water oualiry data. This database is the source of
historicist and up-to-date environmental data for me 16-1}3unty region covered by the District.
The DBHYDRO Browser allows you to search DBHYDRO, using one or more criteria, and to generate a
summary of the data from the available period of record. You can then select data sets of interest and
have the time series data dynamicallf displayed on your screen in tables or graphs. You can also
download data to your computer, for later use.
Figure 3-2 — Main DBHYDRO Portal
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Miscellaneous Items and Reports
Main Menu 1 Home I SFWMD Homy I ,tlser's Guide I What's New J FtiOJ .orris
Figure 3-3 — DBHYDRO Browser Menu
3-5
February.2012
City of Miami
Phase II - Stormwater Management Master Plan Final
a"JSF.t71MD;" ISDmriDistritiubonc,-�AailllaF,rmf"'
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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
February.2012
City of Miami
Phase II - Stormwater Management'MasterPlan Final
STAGE
.d V\EATHER
;r.. 1Aar
LL
wo
City of Miami Limits
r � 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
February 2012
City of Miami
Phase II - Stormwater Management'Master Plan,Final
.Legend
3A-T2, SR MID ERP
Q City or Miami Limits
Basin' Boundaries (DEW) •
Figure 3-6 — SFWMD ERP Permit locations within the City of Miami
3.3.2 National Oceanic and Atmospheric Administration (NOAA)
Tide data is available from the 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/
3-8
February2012 City of Miami
Phase II - Stormwater Management Master Plan Final
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 andFigure-3-8, respectively.
The Virginia Key station is the closest monitor station to the City of Miami. 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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3-9
February.2012
City of Miami
Phase II - Stormwater Management Master Plan Final
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Coastal Assessment ii Resource Economics team (htypi//wwwe.nos.nnea.00s'
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i North-Ati South Atl �[
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(httei//estuennebathvmetrv.neva.cp0A.
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I: National Marine Sanctuariesti l Program (Irtei sanctuaries.noaa.¢av/library/imast ois.tionl)
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it Oceanographic Products end Services
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Figure 3-8 — NOAA GIS data site
3.3.3 United States Army Corps of Engineers (USACE)
In July, 2009, the USAGE 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:
USACE Main Engineer Circular Portal:
o http://140.194.76.129/publications/eng-circulars/
USACE Sea Level Change Engineer Circular (EC 1165-2-211)
o htto://140.194.76.129/publications/ena-circulars/ec1165-2-211 /toc.html
3.3.4 United States Geological Survey (USGS)
The USGS maintains a network of groundwater wells that are monitored continuously in
cooperation with the SFWMD. UroundWater wells are located throughou Tthe City and
County and, in some cases, historical data for wells that have been retired is also
3-10
February.2012
City of Miami
Phase II - Stormwater Management Master Plan Final
available. Groundwater stage data for the various wells throughout the City can be
obtained from the -following website:
Main USGS data portal:
o http://www.sflorida.er.usgs.aov/
Data access site:
o http://www.sflorida.er.usgs.00v/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.
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Current Water -level Conditions in South Florida
Using this Site
PROVISIONAL DATA
Data Collection
Sile status is calculated based on lonp•leml water -level trends, where Identified
Summary of Conditions
USGS Terminoloo.
Y.a=.L File lot Stations Shawn (Right -click link to download file)
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Figure 3-9 — USGS groundwater well data site
3.3.5 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 Geospatial 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 at:
• Main Geospatial Data Gateway Portal:
o htto://dataaateway.nres.usda.gov/
3-11
February 2012 City of Miami '
Phase II-,Stormwater Management Master Plan Final
Additional data is available through this system including digital ortho imagery, digital
elevation models, and other cultural and demographic data.
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he.Geospaddl.Data Gatew,y.(GDG).ic the.One.Stop.Source for
nvironmental end natural resources data, at anytime, from
anywhere, to anyone. The Gateway allows you to choose your
area of interest, browse and select date from our catalog, -
•
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Figure 3-10 — USDA's Geosptial Data Gateway site
3.3.6 Federal Emergency Management Agency (FEMA)
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
—�Governmerit�niill make"flood insurance available within the community as 'a
financial protection against flood fosses. .This insurance is designed to
provide an insurance alternative to disaster assistance to reduce the
3-12
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
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:
"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
floodpiains."
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.
3.4 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 Phase II of the stormwater master plan update
process. The -following subsections detail the pertinent components of the data
collected and their potential role in the development of this stormwater master plan
update.
3.4.1 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 II of the SWMMP can be completed. The most
important data collected from DERM included the hydrologic/hydraulic models prepared
to support the .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 necessary guidance for the
hydrologic/hySi rau is modeling activities require -a as part of P a» e I 61— fills 5171 MMP.
The following are the key points noted in the development of the DERM SWMMPs.
3-13
February.2012 City of Miami
Phase II - Stormwater Management MasterPlan Final
Upon initial evaluation of the DERM models, systems were simulated based on their
main inter -basin 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:
• 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 will be explored further and taken into account in the development of
the Phase II XP-SWMM models.
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 level of service using 'the modeling results .for the 5-, 10-, 25-, 50- and 100-
3-14
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
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 is related to the defined floodplain level of service (FPLOS) as follows:
•• All structures (commercial, residential, and public) should be flood -free during the
100-year storm event.
• Principal arterial roads, including major evacuation routes, should be passable
during the 100-year storm event.
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).
•• Minor arterial roads (up to 4-lanes) should be passable during the 10-year storm
event. 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 above. These severity
indicators are defined and summarized below. Each of these indicators has also
assigned a "weighing factor" (WF), which is related to the relative importance of the
flooding severity indicator.
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)
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 passable 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 table .below. •
3-15
February 2012 City:of Miami
Phase II - Stormwater Management Master Plan Final
Depth.ofFloodinq Abovethe FPLOS E
Lessthan 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.
FPSS . [4 x E(J) x NS]-+[4 x.E(;;) x MER] + [3 x Et;;;y x.BM]
[2 x E(;,,) x MMAS] + [1 x E(v) x MC.LRS]
Once the severity is calculated, the score for each can 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 will yield the basins with the highest flooding
problems based on a 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 value 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
one or none of the five
The City SWMMP will only focus on the 5- and 100-year design storm events.
Modification of this methodology was performed during Phase I of the SWMMP
development process and will be carried through to Phase II.
3.4.2 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 for Phase I to include a number of projects
which were also identified to be providing a potential benefit to the City's stormwater
management system.' The "City's Public 'Works -Department identified . a -'total of -47
projects, of which,. eight (8) will be evaluated for inclusion into Phase II of the SWMMP.
3-16
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
Of the 61 projects listed, project information was provided 'for 47. Attachment A
provides a complete listing of'the projects collected for both Phase I and II.
The project data for the eight projects within the limits of Phase be evaluated
further and their inclusion in the SWMMP is dependent on the type of .system
implemented and the overall function of'the system. The planning -level models 'to be
developed do not typically analyze minor components within a given stormwater
management system. For example, minor improvements that would only provide a
localized benefit within a basin and is primarily associated with conveyance within the
basin rather than exfiltration or conveyance out of .the basin, would not be included
because the benefit would not be realized in'the model.
The City's 1986 Storm Drainage Master Plan was also reviewed to determine if there
are specific contents in the master plan that would streamline development of the 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. The
development of .the sub -basins for Phase II will take into account, when necessary, the
delineations from the 1986 delineation.
3.4.3 SFWMD Rainfall Data
Rainfall data for the long-term monitoring station designated Miami Airport was
downloaded from DBHYDRO. This daily historical data was used to in the frequency
analysis for the rainfall events with durations of 1- and 3-day. The annual time series of
maximum daily rainfall and 3-day rainfall were extracted for analysis and the .Log -
Pearson Type III distribution results were as follows:
-------------
• 3-day 100-year = 18 inches
The SFWMD isohyetal maps also show 6 and 18 inches for the 1-day 5-year, and 3-day
100-year storms respectively. Frequency curves are shown in Figure '3-10 and Figure
3-12.
3-17
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
Frequency Analysis for One -Day Rainfall
loo Miami Airport
tel
0.0
re
CC
10
Recurrence Interval (T)
10
100
Figure 3-11 — One -day Rainfall Frequency Analysis at MIA
:. Frequency ..Analysis .:for ._3=Day_Rainfall _.__;
c
173
co
•
•
•
10
Recurrence Interval (7)
•
•
•
—. —LW.l wswm Ili LHI,,wt,n:
100
Figure 3-12 — Three-day Rainfall Frequency Analysis at MIA
These frequency curves were used to classify some of the larger rainfall events that
occurred between 1979 and 2010 - see Table 3-1, The purpose of this classification is
for comparison of calibrated model results with anecdotal or repetitive loss data. For •
example, the storm in 2000 was classified as approximately 1 in 52 and 1 in 46 years
for the 1-day, 5-year and 3-day, 100-year events, respectively. Therefore, we would
expect the simulation for the 5 year storm to predict flood stages that were less than
3-18
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
that in 2000. Similarly, we would expect the simulation for the 100 year storm.to predict
flood stages that were greaterthan that in 2000.
Table 3-1 -Basin and Watershed Areas within the City of Miami
.A
tS
# Year f
1day
Rainfalls,
(inches)E4
iRecurrence
ii ervaly�
(years)
f 3 ciay�
rainfall
(inches)
:Recufrence3'
s mtania(
:1 years)�
;.1979 :a
'1.4 8;5 *
.. ,.
; __ k100. `:''= r
' :16 24`>
..
_ ;:62
1980
4.02
.4.8
1981
3.13
6.53
b;1982 3
K7.25
+'
E s8. .
8.94
1983
2.66
4.98
1984
4.15
7.93
1985
3.25
4.97
1986
3.9
5.69
1987
3.63
4.5
1988
2.63
4.65
1989
3.54
4.49
1990
2:1
.4179
1i991
c676:;
6 .:: s
: `1.276
.
:22
x,',-
NO 2
6 61 }
',6
8.12
1993
3.16
6.69
1994
4.4
7.22
1995
4.88
9
1996
4.36
4.83
1997
5.97
.6.92
1998
5.86
7.56
1999
5.56
1`0"99
, ::12
2000 r
;;' z1;2.
..i F52 h':: -v...
1:5 -,',i,
.',k
:; 4.6
` - I
2001
4.74
7.92
2002
3.73
4.68
2003
4.19
5.42
2004
2.89
5.01
.2005
4.89
5.64
2006
4.63
6.23
2007
2.94
5.04
2008
3.86
5.14
2009
2.22
3.98
2010
3.6
5.89
Surface water flow and stage, and groundwater data were also downloaded 'from
DBHYDRO. Figure 3-13 shows the locations of the DBHYDRO stations within the
limits of the City of Miami.
3-19
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
jr';'
, S
FS S
• Legend
• ,r'iaHYDRO_Florr_See
`L e D3HYDRO_Stape_Site
ttS
� 0 DfiHYDRO_Gr V,Vater See
Sscayne_S_basins
WI Div DERM! Subbasins
Figure 3-13 — Location of DBHYDRO Gauge Stations
3.5 Data Collection & Evaluation Conclusion
Sufficient data was collected to proceed with the development of phase II of the
stormwater master plan update. Model development will be sufficiently supported by
the available topographic, infrastructure, and other pertinent data required to properly
develop a full hydraulic and hydrologic model.
Calibration and verification will require the use of anecdotal data due to the lack of
canals, rivers, and other points where stage and flow data can be quantified. Both
coastal basins have various points of discharge which are located along Biscayne Bay.
Biscayne Bay is a tidal water body and cannot be used for calibration and verification
purposes.
3-20
February.2012
City of Miami
Phase .II- Stormwater Management Master>;Plan Final
4:1-- Topographic -Data
Topographic data was collected from Miami Dade County in the form shapefiles
containing LiDAR based points. These shapefile were made up of multipoint features
with each point containing horizontal and .vertical data, i.e. location and elevation data.
LiDAR is an optical remote sensing technology which is often used to collect large and
dense quantities of topographic data of a given region at a relatively low cost compared
•to on -the -ground surveying 'techniques. Planes, with the .LiDAR data collectors on
board, are flown systematically over the areas to be surveyed collecting millions of data
points. These data points are collected en masse resulting in occasional data points
representing the tops or sides of buildings, vehicles, structures such as bridges, and
vegetation.
These raw data points .are then taken through a process of correcting and cleaning. to
adjust for vertical correctness of the points and to eliminate features which do not
represent a bare -earth data point. This is typically done using aerial imagery, existing
building footprint GIS data, as well as corrections hard coded .by technicians. The end
result are bare -earth topographic points. •
The LiDAR data provided by Miami Dade County (County) was from the Florida Division
of Emergency Management .(FDEM) Statewide Coastal LiDAR project which included
various data sets covering large •portions of the state of Florida. From •the available
documentation for the LiDAR data, the data has a stated horizontal accuracy of ±3.8-
feet and a vertical accuracy of ±0.64eet. These data .sets were also referenced to the
Florida State Plane NAD83/HARN horizontal datum in feet and -the North American
Vertical Datum of 1988 vertical datum (NAVD88) in feet. Although the accuracy of
these points may appear to have a .significant relative error, this level of accuracy is
sufficient for .the purposes of performing large scale or regional models such as this
SWMMP-update
The relative distribution of the LiDAR points throughout the City of Miami varies
depending on location and building/foliage coverage and no definitive distribution
pattern can be described. In general, most points fall within a distance of 10 to 30-feet
of each other although there are numerous areas where the location and size of building
require the removal of groups of points which then result in large areas containing no
points. Figure 4-1 shows an example of an area where an obvious removal of points
was necessary to achieve the bare -earth effect. A large building is located in this area
and there is a clearly visibly gap where points were removed.
Although the removal of these points creates a number of gaps within the data set,
these gaps-can-be-corrected-through-interpolation-dur-ing-the-creation-of-the-topogr-aphic
TIN and raster (discussed in the following sections).
4-1
February 2012
City of Miami
P.hase II - Stormwater ManagementMaster•Plan Final
Legend
d ..LiDAR .Points
Figure 4=1 — LiDAR Point Distribution
4.2 Datum Shift
The LiDAR data collected from the County was referenced to the North American
Vertical Datum of 1988 vertical datum (NAVD 88). In Miami Dade County, the NAVD 88
datum is lower than both the National Geodetic Vertical Datum of 1929 (NGVD 29) and
the City of Miami Datum (CMD). The NGVD 29 datum is also lower than the City of
Miami Datum. Table 4-1 provides the conversion relationships for the three datums
referred to along with an example of a conversion referenced to an elevation of
0.00 ft-NGVD 29.
Table 4-1 — Vertical Datum Conversion
ti
r
A3 1 "t'
„tiD:atum,
{ }
� ati � ,, ;� .�', " �r . ��, ��,
S>.. ,,;<Conver ion.Value.,. .;„ ..
g.,AN �z,
Serb- >, .. Z✓ ?:��N , �
Conversion Equation „-
"Sample Elevations
i . yt 1�
(assume.0 00,t N.G1%Dr29)a
CMD
0.26 (to NGVD)
NGVD 29 + CV* =CMD
0.26 ft-CMD
NAVD 88
-1.55 (to NGVD 29 - varies)
NGVD 29 + CV* = NAVD
-1.55 ft-NAVD 88
NGVD 29
1.55 (to NGVD 88 - varies)
NAVD 88 + CV* = NGVD
0.00 ft-NGVD 29
CV = Conversion Value
The City of Miami Datum has a constant conversion value of +0.26 feet to NGVD 29 as
referenced in Table 4-1. The conversion between NGVD 29 and NAVD 88 varies
4-2
February 2012 City of Miami
Phase II - Stormwater Management Master -Plan Final
slightly throughout the City. For this .conversion,' the SFWMD has developed a raster
dataset which provides the conversion .value between the datums. This conversion
value- ranges „between.-'1-54 to.-1.57..feet-within.the..City_of.:Miahii..limits....The._0...0.3.:feet
range represents a .variation of 0.36 inches of variation betweenthe.datums depending
on location with a smaller variation of 0.02 feet in Phase II. This variation is negligible
for this large.scale study and will be applied uniformly using an average value of -1.55
feet throughout the limits of the City. Figure 4 2 provides a figure •showing the datum
conversion values -throughout the City.
Legend
Datum Shift
Value
-1.54
-1..55
-1.55
-1.57
Figure 4-2 - NAVD 88 to NGVD 29 Datum Shift
4.3 TIN Creation
A topographic triangulated irregular network, or topographic TIN, is a geometric
representation of a surface. TINs are composed of vector based triangular shapes
meaning that each vertex on the triangle has an absolute location and each edge
connects to each point along a straight dimensionless line. The viewing scale for a TIN
does not affect the clarity of the surface and dimensions can be triangulated off of each
of the triangles composing a surface.
TINs are more accurate at representing a surface than rasters because each
topographic point used when creating theTINcap ured in the surface. The density of
the points used to create a TIN increases the level of accuracy in the representation of
4-3
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
the surface. Additionally, locations between points can be accurately interpolated
based on the three points composing each.triangle.
For this project, the TIN was developed using ESRI's ArcMap using 3D Analyst. This
software package creates a TIN from the LiDAR .based multipoint shapefiles. This TIN
was used as the base for raster to be used for this project. Figure 4-3 shows a typical
area within the City where a TIN was created using LiDAR points.
Figure 4-3 — TIN Representation
For areas where LiDAR points were removed because of false returns from buildings or
vegetation, -the TIN is formed by connecting points across these empty areas to create
the...TIN's triangles.. The resulting interpolated. values, are__.re.presentative., of the
estimated bare earth values in those areas. Figure 4-4 shows an example where this
type of gap interpolation was performed. This figure shows the same area as in Figure
4-1 where a large building resulted in points being deleted. Interpolating in areas such
as those where points were eliminated results in a relatively accurate bare -earth
representation of an area. This is the best method of defining areas such as these.
Due to the quantity of points Used to create and the subsequent complexity of the
resulting TIN, large scale TINs, such as the one for the City of Miami, often tax
computer systems when being visualized in a GIS platform or being used for
calculations or analyses. For the majority of applications, a raster can be developed
from a TIN to facilitate map making and calculations.
4-4
February.2012
City of Miami
Phase II - Stormwater Management Master Plan Final
•
' �►=•y-. _ *-41!.-44:... . !
o"° L end a=s..�..� a "-
• UDAR Points q=-^" '•.et..
i4.
•
•
— TIN
_�
F•
_t
• i • ,0 6'�•-ic s.—� -o. •\ 'pro �� • $.
e� a �y y •s �°�y +ysyf I _ 6 °. �r .;�
•
6::'.."r" . '•.RP ; 4.__t. ., yam' :: _-.cy.. __
Figure 4-4 — TIN - Gap Interpolation
4.4 Raster Creation
A raster based dataset is another way of representing a topographic surface in GIS.
Raster data sets use square cells to represent values - in this case values representing
elevations. .Each square represents an averaged elevation dependent on the elevations
present within the limits of each cell. The square cell also has a horizontal dimension
which can be defined depending on the coarseness of the topographic raster desired.
Additionally, 'the smaller the size of the cell defined, the larger the size of the raster
dataset. See .Figure .4-5 for.a sample area showing..topographic..LiDAR..points .and the__
resulting TIN and raster dataset for this project.
For the development of this raster, 3D Analyst was used to convert the TIN into a raster
dataset. The cell size dimension defined for the raster was 25-feet by 25-feet. This
dimension provides sufficient resolution for calculating stage -area relationships and
determining high and low areas within the City while maintaining a file which can be
displayed with relative ease on most computers and is fine enough to be visually
pleasing on most maps. This resolution is sufficient for the purposes of this planning -
level study.
4-5
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
Legend
• LiDAR Points
TIN
Figure 4-5 — Raster Dataset Representation
4.5 Resulting Raster Dataset
The resulting raster dataset for the City of Miami showed obvious locations where high
and low topographic elevations where present. These rasters also correlated well with
the topographic maps available from the DERM Stormwater Master Plans when
compared visually. The raster was also developed with a buffer distance of .1,000-feet
beyond the_physical limits of the City.
The lowest areas within the City are the areas adjacent to the Miami River and the C-4
Canal. Low topographic elevations are also present along coastal areas within the
North and South Biscayne basins. Coastal ridges can also be interpreted from the
raster where elevations are noticeably higher than elevations found further inland.
Local and major roadways as well as highways are also easily distinguished throughout
the digital terrain model (DTM). Bodies of water can also be seen although few large
water bodies exist within the limits of Phase II of the SWMMP.
Figure 4-6 shows the resulting raster DTM of the City of Miami. The range of the
elevations where truncated to elevations between 0 and 14 feet-NGVD 29. This color
ramping in the symbology makes the representative map easier to interpret when trying
to distinguish the major topographic features within the City. Although the symbology
was truncated for this elevation range, elevations do remain in the original raster and
will be used in all calculations for the hydraulic and hydrologic models.
4-6
February 2012
Cityof:Miami
Phase II-- StormwaterManagement .Master: Plan=Final
Legend
City of Miami-DEM
Elevation (ft-NGVD)
Above 14
Figure 4-6 — City of Miami DEM
The raster based DTM will be provided to the City in a digital format viewable in ESRI's
ArcMap GIS platform. The DTM will also be in both the NGVD 29 vertical datum and
the City of Miami datum. All digital data produced for both Phase I and Phase II of this.
SWMMP will be provided with the final report of this.phase.
4-7
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
4.6 DTM Development -Conclusion
The .topographic...digital...ter.rain..model..was.developed_ ..using . relatively_ accurate_ and
representative LiDAR data sets of the City of Miami. The density of the points collected
by FDEM and the filtering of the datasets for .structures and vegetation resulted in a
topographic model that is representative of the bare -earth nature of the region. These
LiDAR points also provided accurate interpretations of the City's topography with a
relatively small average elevation error of 0.6 feet.
The resulting raster DTM with 25 foot by .25 foot cell resolution provides a way of
accurately determining sub -basin boundaries within the City as well as a way of
calculating stage -area relationships for all areas within the City. Additionally, all of the
City's major topographic features can be easily distinguished when viewed dynamically
in GIS or in properly symbolized maps. Major roadways, local roads, and water bodies
are all visible from the raster based DTM.
The DTM will be. provided in both the NGVD 29 vertical datum and the City of Miami
vertical datum. The DTM covers the entire limits of the City of Miami. Attachment C
contains maps showing the DTM created for this SWMMP symbolized as noted on each
map.
4-8
February 2012
City ofMiami
Phase II - Stormwater Management MasterPian`Final
During the development of Phase I of this rSWMMP 'Update, it determined that
utilizing the DERM models as developed by. DERM would be a time -saving and cost-
effective approach at developing the SWMMP for these areas already analyzed by
DERM. These models had their own respective sub basin delineations and were not
revised in Phase I due to the complexity bf re -delineating boundaries, verifying
interbasin connectivity, and re -establishing -the calibration of the models based on any
changes.
For Phase II, no sub -basin delineations were developed by DERM for the coastal basins
because no models were developed. As such, sub -basin delineations were developed
for this Phase of the SWMMP. The details of this delineation are described in the
following sections.
5.1 City .ofrMiami Delineation
*City sub -basin delineations are in yellow and stormwater infrastructure is in red.
Figure 5-1 City of Miami Sub -basin Delineation
5-1
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
The City of Miami maintains GIS.. data which defines. the City's drainage sub -basins
based on existing stormwater managements.ystems-andthe best available -topographic
data.....present timeThis._.sub-basin...delineation..._ was..provided_. in a. ,format
compatible with :ESRI's ArcMap GIS platform. The sub -basins are generally divided
based on quadrants bounded by major roads with additional sub -basins being divided
based on contributing areas .to major roadway systems. Figure 5=1 presents an area
showing where sub=basin divides where delineated along 27th and 22nd Avenues and
large interior areas- which were grouped into a single sub -basin. This is common
throughout -the City's delineation.
When these same sub -basin divides are viewed in relation to -the raster DTM developed
for this SWMMP, some clear divides can be interpreted where none exist. Figure 5-2
provides an example of where a divide could have been delineated along a topographic
ridge .at the time given more detailed topographic information such as the LiDAR data
currently available through the County from the Florida Department of Emergency
Management (FDEM). The sub -basin delineations from .the City appear to be more
directly influenced by the available infrastructure data rather than topographic data.
'City sub -basin delineations are in black and stormwater infrastructure is in red.
Figure 5-2 — City of Miami Sub -basin Delineation - with DTM
Additionally, the sub -basin delineation provided by the City did not align well with the
coastal boundaries of the City available in GIS nor the observed coastal boundaries
5-2
February,2012 City of. Miami
Phase II - Stormwater Management Master. Plan. Final
visibllein the hi -resolution aerial. images. This misalignment was corrected in':GIS using
the City's land mass . GIS file. All boundaries -along the coast :and along . major
waterways; for_ the:P_hase.. ll<.limits.. of: the.'SWMMP_were.:corrected and:now. snatch exactly..
with 'the landmass .file. This correction allows for accurate.:stage-area''. relationships.
Figur..e.5=3_provides an example of the correction: performed on .the sub -basins coastal
boundaries. There -delineation of these sub -basin boundaries.wiill.be described in more
detailed in the following sections
'Original City sub -basin delineations are in red and the revised delineations are in .yellow.
Figure 5-3 — Coastal Boundary in Sub -basin Delineation
5.2 City of Miami .Infrastructure Data
The City of Miami also maintains GIS data which defines the stormwater infrastructure
in place and is intermittently labeled with various names identifying the type of facility in
place. The location, connectivity, and labels in the GIS file were derived from the City of
Miami Stormwater Atlas sheets available in hard copy from the City. These Stormwater
Atlas sheets were digitized into GIS at some point by the City and, although
schematically correct in terms of relative location and extent, are not spatially accurate
when referenced to the available orthographic aerial imagery. Most of the items in
these GIS files do not align 'themselves precisely with what can -be viewed in 'the high —
resolution aerial images. In Figure 5-4, the alignment of the GIS file (yellow structures
and red lines) shows catch basins being located in the middle of the street while the
5-3
February.2012 City of Miami
Phase II - Stormwater Management Master Planfinal
catch .basins can::be clearly seen in °the aerial (cyan structure.$) and located in typical
locations where curb inlets would be located. •
The •niisalignment.of the existing systems is not a concern -for-this SWMMP and does
not adversely affect any of the.assumptions or results of -the analyses 'to be.performed,
but could potentially be addressed at a later date by the City. 'The main function of
these GIS files for this SWMMP will be to identify connectivity..and coverage extent of
the systems in place. An update to certain systems will'be performed for a particular set
of projects as a part of this SWMMP and will be addressed in'TM#9•- City Stormwater
Infrastructure:Atlas Update, under separate cover: and. delivered digitallly:to; the City.
**City infrastructure data in yellow and red and the actual location of structures are in cyan.
Figure 5-4 — Infrastructure Alignment
In addition to the connectivity of the systems in place, the types of systems servicing the
City's sub -basins can also be identified Using the GIS infrastructure file from the City.
These systems can primarily be classified into four types; 1) systems which convey
runoff out of a sub -basin to a discharge point; 2) systems which facilitate the infiltration
.of runoff into the groundwater table with designed overflows to a discharge point; 3)
systems which facilitate the infiltration of runoff into the groundwater table with no
designed overflows; and 4) areas where no systems are in place and which rely on
infiltration through the surface.
5-4
February.2012
City of Miami
Phase II - Stormwater Management Master Plan -Final
"Table -55-1 provides .a .breakdown. of the totallength of each type of -facility.•grou.ped by
the labeled infrastructure type For -this GIS file, objects labeled with FD, CD - D, and
TR_represent... exfiltration_systems which convey runoff to the groundwater table..,": The
remaining objects are defined as solid pipes. A large number of pipes have no label
and will be conservatively grouped as solid pipes. These quantities will -be further
broken down by basin and will be attributed to infiltration -to -the groundwater table,
where applicable.
Table 5-1 — GIS Stormwater Infrastructure Totals
,k t
> aGIStia: alf
� r q 7
Total Lengthx(ft)
1,��`4 " "S i i j 'c
.z ,� "Descr 07170 , ,
XD
648,271
Solid Pipe
FD
574,036
Exfiltration Trench
--
498,763
Unknown
CD
282,220
Exfiltration Trench
PO
250,870
Solid Pipe
PD
9,264
Solid Pipe
TR
8,669
Exfiltration Trench
BO
2,227
Solid Pipe
*` Items labeled PC, RD, DS, OJ, XP, RG, BD, D, SD, XS, PL, DI all have
under 800 feet or less of pipe length identified within the City .
Additionally, the connectivity of the systems can be assumed based on the location of
the lines relative to one another. This is the best available data and will be used to
determine interbasin connections as well as to locate outfalls and determine sub -basin
limits.
5.3 Topographic Data
The topographic raster dataset developed for the City of Miami showed obvious
locations where_ high and low topographic elevations_ where_present._. The _lowest areas_
within the City are the areas adjacent to the Miami River and the C-4 Canal. Low
topographic elevations are also present along coastal areas within the North and South
Biscayne basins. Coastal ridges can also be interpreted from the raster where
elevations are noticeably higher than elevations found further inland. Figure 4-6 shows
the raster DTM developed for the City of Miami symbolized to identify key topographic
features. The range of the elevations in this figure where truncated to elevations
between 0 and 14 feet-NGVD 29 for the purposes of clarity.
The raster based DTM allows for high and low topographic areas to be visually
identified as areas where natural basin breaks exist or where runoff is collected,
respectively. Topographic ridges represent high areas where a break in the flow of •
runoff will most likely occur. Runoff will flow perpendicular to a ridges and continue
down to lower lying areas. Runoff flowing from high elevations will congregate in low
lying areas and remain there until removed from the sub -basin via conveyance systems,
infiltration, evaporation, or a combination thereof.
5-5
February.2012
City of Miami
Phase II- Stormwater Management Master Plan Final
Floodwaters within a delineated sub -basin cannot -cross along, ridges, to an adjacent
sub-basinunless the depth of flooding in a sub -basin -exceeds -the .lowest elevation
..along.jhat.boundary.,Theseridgeswill...bedefinedas,cross sections,;when,;modeled in_
XPSWMM, when necessary. In most cases, ridges represent .the outer limits of:a•sub-
.basin and will be -the location of sub -basin divides. They can be naturally elevated
areas or areas where man made divides:such as highways exist. See Figure•5-6-for an
example of sub=basins delineated along topographic ridges.
Legend
City of Miami DEM
Elevation (ft-NGVD)
Above 14
Figure 5-5 — City of Miami DEM
5-6
February.2012
Cityof.Miami
Phase II - Stormwater Management.Master Plan Final
Legend
Phase II Sub -basins
City of Miami DEM
Elevation (ft-NGVD)
rw-,,•.,�, Above14
Figure 5-6 — Delineated Sub -basins Based on Topography
Floodwaters within a sub -basin will generally collect in low lying areas unless conveyed
out of a sub -basin by stormwater infrastructure. Low lying areas will generally be
bounded by ridge lines or a coastal boundary. For regional models such as the one
being developed for this SWMMP, these low lying areas.will represent the areas Where
the majority of flood waters will congregate during a storm event. These low lying areas
are also the most susceptible to inadequate stormwater management systems and,
thus, flooding.
5.4 Delineation Methodology
The delineation process involved multiple iterations where sub -basins were divided,
joined, and/or refined using the topographic and stormwater infrastructure data
described in the previous sections. The basis for this SWMMP's delineations were the
original City of Miami sub -basins available in GIS. This original delineation was closely
analyzed and refined based on a close inspection of the available data.
The limits of the Phase II sub -basins overlap with the limits of the Phase I sub -basins.
During the development of the .DERM stormwater master plans, the limits of .the major
watersheds were defined based on the existing limits of the SFWMD watersheds. The
5-7
February 2012
City of Miarni
Phase II - Stormwater Management Master PIan'Final
limits were refined based. on topography and infrastructure, data but Were not.,changed
significantly: in order to maintain concurrency:with the long-established, delineations°from
:the ..S.F.WMD... For...this....S.WMMP, these .limits.... were., not.�_used.:as., a, limitingJactor.in
defining -the boundaries of the north and south coastal basins and, for this reason, the
overlaps shown in Figure 5-7 exist. This overlap will also be addressed in the
subsequent ranking procedures.
Legend
City of Miami Land Mass
Phase I Sub -basin Limits
Phase II Sub -basin Limits
North Basins
EgM South Basins
Figure 5-7—Phase I and Phase II Sub -basin Limits & Overlap
The north and south basins were divided by the Miami River and the limits of the north
basin were primarily defined by the northern limits of the City, 1-95 on the west, and the
coast on the east. Additionally, the systems present in these areas also resulted in the
defined limits being extended beyond 1-95 in certain areas to accommodate for
interconnectivity with systems which cross underneath 1-95. Figure 5-8 shows the
delineation of the north basin for Phase II.
5-8
February.2012
City of Miami
Phase:11:-:StormwaterManagement Master Plan Final
Figure 5-8 — Phase II Sub -basin Limits - North Basin
The limits of the south basin were primarily bounded on the north by. a ridge which runs
from east to west with a noticeable arc northward beginning about 1.5 miles inland. The
western limit is along SW 37th Avenue which is the western limit of the City. NW 37th
Ave_au_e co_ntaia_sstormwater_management_systemsuvhiclLinietc_ep_t_..stormwate_r_ruaoff
being transferred towards the west when the conditions arise. The southern and
eastern limits are the coast as in the north basin. Figure 5-9 shows the delineation of
the south basin for Phase II.
5-9
February.2012
City of'Miami
Phase II.-.Stormwater'Managemeht.Master Plan Final
M. ajor Conveyance
::System,.&�I,i mlfs;of
City;of_Miam1=
Figure 5-9— Phase II Sub -basin Limits - South Basin
Attempts were made to maintain some uniformity between the sub -basin sizes in order
"to not "have disproportionate weighing of .the sub -:basins When performing rankings or
developing project costs. Unfortunately, because the sub -basins were dependent on
the existing stormwater infrastructure and the random topographic nature of the City,
this was not possible. The delineation activities resulted in 56 northern sub -basin and
39 southern sub -basin, with an average of 85.8 acres and 186.1 acres, respectively.
Attempts to further divide or join basins to make them more uniform was attempted but
it was observed that it would only result .in creating models that were not was
representative as ones using the delineation developed. Additionally, a methodology
was developed in Phase I of the SWMMP in order to address issues such as this.
The naming convention for the sub -basin delineation was dependent on the location.
For sub -basins in the north, a prefix of NB was used and similarly for sub -basins in the
soJth; a prefix cif -SIB -was- used.. The numbering applied -from south to north—from-0110
95 for the 95 sub -basins. Table 5-2 provides a listing of the name and area of. each
sub -basin.
5-10
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
Table 5-2 - Sub -basin Names& _Areas:
;Sufi
..
Kk? bas k
ma yy,' ..0 '
i 5.
(acres) - i basin
7,; ?A a
FY'i7
. ; (acres)
[y:,Sub`} ,,
t�bas.►n
tl' ";Tiea xw
4 VR x I.i' I'xt 4�+a
z (�acres);t
SB01
.26.9
-". :. SB33
321.3
`. 'NB65
71:2
SB02
41.2
h - ' SB34
337,0
4_ ! NB66
72:2
SB03
43.1
SB35
346.1
: NB67
73.8
SB04
61.5
• ' :R';: "+ SB36
355.2
';: ' NB68
79.1
SB05
70.8
' ii SB37
435.3
:':- NB69
79.3
SB06
75.7
- SB38
483.0
NB70
82.5
S807
77.4
:'. S839
525.5
' NB71
84.1
SB08
80.1
. NB40
.20.6
" NB72
85.9
SB09
89.0
`" ' NB41
23.4
it`- NB73
89.0
SB10
94.1
i?, NB42
28.5
NB74
90.2
SB11
95.5
. NB43
30.1
' NB75
90.6
SB12
116.6
: NB44
32.1
` .. NB76 .
95:1
SB13
119.8
NB45
35.3
<< NB77
97.7
SB14
121.2
NB46
36.8
=, NB78
108.0
SB15
127.6
NB47 .
37.1
a NB79
110.2
SB16
131.1
' . N648
37.9
NB80
111.9
SB17
133.7
'NB49
39.2
', NB81
124.2
SB18
141.0
NB50
41.4
.. NB82
279.9
SB19
157.3
>' NB51
42.9
:' NB83
126.8
SB20
166.4
NB52
43.5
.' NB84
130.7
SB21
166.7
NB53
46.9
;` NB85
131.6
SB22
172.9
NB54
47.4
NB86
131.8
SB23
186.2
;:'. NB55
50.9
NB87
133.9
S624
187.6
`..'.. NB56
50.9
NB88
140.4
SB25
190.3
: NB57
, 60.4
:;: NB89
141.9
SB26
191.4
" NB58
62.2
".' NB90
147.5
SB27
195.2
F3I NB59
62.6
;;' NB91
155.1
SB28
225.4
`.' NB60
64.2
NB92
174.3
SB29
226.3
NB61
68.4
N893
176.2
SB30
236.7
; NB62
68.8
`< NB94
182.6
SB31
251.8
°. N863
68.8
NB95
192.9
SB32
256.1
NB64
69.6
!
Each sub -basin delineated for Phase II was analyzed in order to identify the method by
which stormwater runoff is either conveyed out of the sub -basin or into the groundwater
table. This analysis was performed in order to properly identify the hydraulic network
that will used in the XP-SWMM models. Maps of the final sub -basin delineation are
available -in -Attachment D.
5-11
February 2012 City.of Miami
Phase II •- Stormwater Management Master Plan Final
5.5 Sub.'-.BasinDevelopmentConclusion
11,_of .the City_ of Miarni Stormwater
Management Master Plan .update was developed using the ?best available :topographic
and infrastructure data. Although the City is in possession of an existing sub,basin
delineation, this delineation was a number of years old and appeared to -not take into
account the detailed topographic elevations that were available forthis study. LiDAR
data, with a relative stated horizontal -accuracy of :±3.84ebt and a vertical. accuracy of
±0.6-feet, is an excellent source for planning -level topographic elevations and provides
a clear indication of the high and low areas within the City. Additionally, the City's GIS
files showing -the location of outfalls, primary conveyance systems, and extent of
stormwater infrastructure coverage, also facilitate the delineation process.
The detailed nature of the data available for this SWMMP update allowed for a more
precise delineation of the City's hydraulic basins. Although attempts were made to
maintain uniformity between the sub -basin sizes for.the purposes of the ranking tasks,
the nature of the systems and topography supersede this need and -were addressed in
the ranking procedure as was done for Phase I of this SWMMP update.
5-12
February 2012
City of..Miami
Phase II- Stormwater Management' Master= Plan;; Final.
For- the,. hydraulic and-hydrologic-(H&H) model.devellopment,process,.it-was-decided that -
two separate XP-S1NMM models would be developed which coincide with the limits.of
the North Biscayne Basin (NBB) and South Biscayne :Basin (SBB), because these
basins are divided by the Miami River and arehydraulically independent. The general
major basin boundaries for the NBB and SBB areas shown on Fiigwe i1=1.
The H&H model development process is divided into several major steps, each with its
own internal components. This process typically undergoes the following general
methodology:
1 Collect all available data including:
a. Topographic data
b. Land use data
c. Stormwater infrastructure data
d. Historical groundwater stage data
e. Historical surface water stage and flow data
f. Historical rainfall depth and duration data
g. Historical flood data
2. Map topographic features
a. Identify topographic ridges and critically low areas
3. Delineate sub -basins using infrastructure and topographic data
4. Define inter -basin connectivity and boundary conditions such as:
a. Overland weirs
b. Major conveyance systems
c. Retention, detention or exfiltration systems (BMPs)
d. Outfails
e. Canals/RiversNVater Bodies stage and/or flow and duration
f. Adjacent basin model boundary conditions
g. Pump stations
5. Populate hydraulic and hydrologic model input parameters such as:
a. Rainfall parameters
b. Sub-basin/catchment hydrologicparameters •
c. Interbasin connectivity parameters for pipes/weirs/channels/etc.
6. Calibrate and verify model
a. Define calibration and verification events
b. Debug model and resolve model instabilities
c. Prepare flood maps for review
d. Compare known historical data to simulated results
7. Simulate design storm events
6-1
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
Steps 1 through 3 have been completed in the previous sections with steps 4 through 7
of this process are to be performed in this section.
The model development process for this SWMMP has undertaken a similar approach as
the one developed and followed by DERM for all major canal basins within the County.
DERM developed procedures under Part 1, Planning Criteria and Procedures and
Volume 2, Model Evaluation and Selection (CH2M Hill, January 1996) of the Miami
Dade County Stormwater Master Plan Project in order to standardize the basin models
and achieve homogeneous and comprehensive SWMMPs for the unincorporated areas
in the County.
In addition to the County documenting the procedures for the development of their
SWMMPs, these documents also define the H&H modeling platform chosen by the
County for the analyses performed on the various canal basins within the County. All
hydrologic and hydraulic modeling activities performed by DERM were done using the
XP-SWMM hydraulic and hydrologic (H&H) computer model developed by XP-Software
Inc. XP-SWMM builds upon the Storm Water Management Model (SWMM) developed
by the United States Environmental Protection Agency (EPA) and is approved by FEMA
and various other State and local agencies for water quantity and quality analyses.
XP-SWMM offers enhancements over EPA SWMM, some of which include an easy to
use graphical interface, various mathematical enhancements to the solution algorithms,
as well as having interfacing capabilities with GIS and AutoCAD files.
XP-SWMM is comprised of three mathematical engines or blocks: the Runoff, Extran,
and Sanitary Blocks. The Runoff Block is used to generate hydrographs using either of
the following well -accepted hydrologic methods:
• EPA Runoff
Laurenson
• SCS Hydrology
Nash
Synder
• Clark
• Santa Barbara Unit Hydrograph
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 a canal system. These connections generate groundwater
hydrographs that are added to the surface runoff for defined canal reaches. These
capabilities were used by DERM to account for groundwater contribution from closed
basins to the canal network, which could be substantial for long duration rainfall events,
due to the highly transmissive soils found in Miami -Dade County. Pollutant loading will
not be evaluated -in this SWMMP.---
The .Extran, or Hydraulic, Block is used to dynamically route the hydrographs generated
with the Runoff Block using the Saint-Venant dynamic wave equations. XP-SWMM
6-2
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
gives the user the flexibility to solve the full dynamic wave equation or the simplified
kinematic wave equation. The Hydraulics block represents all of the conveyance
systems within a network - be them manmade such as a pipe network or naturally
occurring such as those associated with overland flow based on topographic features.
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 canal basins within Miami -
Dade County. 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.
Calibration of the XP-SWMM models was performed in a more unconventional
approach due to the absence of stage, flow, and runoff volume data within the City's two
coastal basins. This is the case because there are no canals, streams, rivers or lakes
within these two basins, which are generally the locations where stage and flow data
are gathered and where comparisons for calibration can best be performed. Due to this
unique condition, calibration was performed by obtaining input from the City in the form
of verification of flood plains derived from the results obtained from the completed
models and comparisons made with recorded flood complaint data.
The following subsections describe the methodology and specific pertinent items
populated within the XP-SWMM model Runoff and Extran Blocks to arrive at a fully
functioning and representative H&H model of the City of Miami's coastal basins. The
XP-SWMM model Version 12.3 was used for the Phase II of .the City SWMMP. The
input parameters for the Runoff Block and the Extran Block are included in Attachment
F through Attachment I for the Hurricane Irene, No -Name Storm, 5-year, .24-hour, and
100-year, 72-hour event models, respectively, for the NBB and SBB.
6.1 Runoff Block Model Setup
In the development of the XP-SWMM models for the inland canal 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 and provide unique names
for each sub -basin. Each sub -basin was identified with the first two letters being NB or
SB for the North Biscayne Basin or South Biscayne Basin, respectively.
6.1.1 Land Use
The land use conditions within the City of Miami have remained relatively static over the
last decade, with minor changes occurring to already developed areas within the City.
This is primarily due to the built out- nature of the City, where the vast majority of
developable land having already been developed to the limits approved by local zoning
codes. Because of this existing condition, the need for an existing and future land use
6-3
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
condition is not required, due to the negligible difference in results which would be
expected with models reflecting any changes as a result of land use differences.
6.1.2 Infiltration
In the Runoff Block, XP-SWMM allows for up to five (5) sub -catchments in 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:
• 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
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 majority of
exfiltration trench systems were no longer able to control the total 5-year, 24-hour storm
volumes due the age of most of the systems in place. The following Horton infiltration
parameters were used by the County 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-Ampt method, as was performed by DERM:
• 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)=-0-02inches
• 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
6-4
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
• Percent of DCIA without Detention Storage (PCTZER) — 25
For the City of Miami's models, it was 'found after initial model runs that the Green-Ampt
infiltration method yielded infiltration rates that were found to exceed what was
determined to be acceptable. For example, many of the subcatchments within sub -
basins serviced by BMPs and using the Green-Ampt method had zero runoff produced
under the 5-year, 24-hour design storm event. This occurred because the entire rainfall
depth was infiltrated. It was determined that the main contributing factor was the
inability to control the maximum infiltration volume as is possible when using the Horton
method. Because of these unexpected results, and because of previous experiences
during the development of Phase I of the City's SWMMP, it was determined that utilizing
the Horton infiltration method would be the best approach for the Phase II models. The
following Horton infiltration parameters, captured from the adjacent C-6 Basin model,
were used to simulate all runoff produced for all sub -basins within the City's coastal
basins - see Figure 6-1:
• Maximum Infiltration Rate — 4.0 in/hr
• Minimum Infiltration Rate —1.25 in/hr
• Decay Rate of Infiltration — 0.00115 sec-1
• Maximum Infiltration Volume — 5.0 inches
• Impervious Area Depression Storage (IDS) - 0.5 inches
• Pervious Area Depression Storage (PDS) 1.0 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
I` ?SC3'Ltn'e'Pk.NY;i ;:
Figure 6-1 — XP-SWMM Horton Method Input Parameters
Additionally, as was done in Phase I of the City's SWMMP process, an extraction
methodology utilizing prorated reductions in rainfall depths unique to each sub -basin
was used to simulate extraction volumes due to BMPs such as exfiltration- trenches.
Thi.s_was_p,erfpr_merl_in_lieu�f�s.ing_the_HoEton _MefhacLas_pe. me.d_b-y._.D_E
account for exfiltration BMPs. This extraction methodology 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 rainfall event over the area contributing to the
exfiltration trench - this is an accepted practice by DERM and the SFWMD. The
6-5
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
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.
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
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 6-2.
Figure 6-2 — Area Attributed to an Exfiltration Trench Length
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 6-1 provides an
example of how the extraction methodology for exfiltration trenches was calculated for a
sample•sub=basin
6-6
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
Calculation Example 6-1 — Exfiltration Trench Extraction Example
+ ^a4qfr, ,
rolect#&7'Sub"basin s
,Informatinn -_ C ti;
rr = rx i.0 ''�''3 �v
,,,,vi _.-nf .: y ._' __. , .,_, -
Sub -basin Name = @@@@
Basin total area = 112.17 acres
Project # = B-XXXX
Construction Date = 5/1/1991
t# � -ow "
ii, . reae`Attnbuth- o `
1Exfiltration` Trench
,I,J4giMg4gPeglififOM P
Exfiltration trench length for project = 7,906 If
Contributingwidth = 320 ft
Total drainage area = (7.906 If x 320 If) / 43.560 = 58.08 acres
h z` p s
`�" 3 '
4 ainfall EW,actton k
ri�
Depth Determination
,,., . , .,,„ ? -A-'
Extraction depth per unit area = 3.28"
Prorated extraction depth = (3.28" x 58.08 acres)/ 112.17 acres = 1.6983"
p ('
Age of Project = 19.1 Years
Reduction % = 19.1 years x 1.0% per year = 19.1
Reduced Reduced Extraction depth = (1.6983" x (100% - 19.1 %)) = 1.3739"
G ;s� " _
t., ,,-- r�Rai;-lv � -
KParameteisr'�r }
i
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° YearZ,Rai.Mrtfafl
#t?arameteraill .� k
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
' " = g.r,
410D Year#Rainfall �� °5 '
' 4
i a kti
Original 100- ear sub -basin rainfall multiplier = 13.65
g y p
Original 100-year sub -basin rainfall depth = 1.359"
Resulting 100-year sub -basin rainfall depth = 18.5504"
tRev se0100 `.Year * 1
¢Ramfall.P Tameters;'s : ,h; I
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
For the remaining parameters, 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:
4. Catchment Areas were determined by the areas available from the polygons in
the sub -basin delineation GIS shapefiles.
• 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
based on representative measured values, as outlined in Table 6-2. These
values were used to establish weighted DCIAs based on the extent of the
specific -land -uses -within -each -sub-catchment.
•
The Width of the basin is an estimate of the overland flow pathway width across
the basin. Sub -basin widths were calculated in GIS using the sub -basin
delineation shapefile, the DEM, and manually determining the width (in feet) of
each sub -basin based on the perceived direction of flow within the sub -basin -
the flow path direction being from higher elevations to lower elevations. Once all
sub -basin widths were determined a simple calculation was performed to
determine sub -basin length: sub -basin length (ft) = area (ft2) / width (ft). The
width of the basin, like the slope, affects the shape of the runoff hydrograph.
Large widths relative to the area produce high peak flows; whereas small widths
attenuate the overland flow.The Slope was established based on the average
overland-slope-of-the-sub-basins-using-GIS-tools-and-the-developed DT-M.
• For each sub —basin, XP-SWMM requires the total impervious areas (TIA) be
defined. The information shown in Table 6-2 was developed based on the
DERM reports for C-3/5, C-4, C-6, and C-7. Additionally, each sub -basin's land
6-7
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
use parameters were populated in GIS using the SFWMD 04-05 land use
coverage. These values where then area -weighted for each sub -basin to
develop the final TIA for each sub -basin.
Table 6-2 - Total Impervious Area per Land Use Category
eFLUCC..``
4, v I O escri tkon. , :•-.L n .; x ,
"`�::r�z,h4v..�;;-,Y":y<.�. p .fir c � s.,. ;fix.
o:.
iA �°/`j
1110
Fixed Single Family Units (< 2 dwelling units/acre)
65
1210
Fixed Single Family Units
71
1310
Fixed Single Family Units (6 or more dwelling units/acre),
65
1320
Mobile Home Units
75
1330
Multiple Dwelling Units, Low Rise
70
1340
Multiple Dwelling Units, High Rise
70
1390
High Density, Under Construction
70
1400
Commercial and Services
75
1411
Shopping Centers
83
1480
Cemeteries
83
1490
Commercial and Services Under Construction
83
1550
Other Light Industrial
83
1560
Other Heavy Industrial
83
1700
Institutional
60
1710
Educational Facilities
65
1830
Race Tracks
50
1840
Marinas and Fish Camps
5
1850
Parks and Zoos
30
1870
Stadiums - Not academic
80
1900
Open Land
3
• 4200
Upland Hardwood Forests
0
5120
Channelized Waterways, Canals
10
5300
Reservoirs
100
5410
Embayments opening directly to the Gulf or Ocean
100
612D
Mangrove Swamp
100
8100
Transportation
83
8120
Railroads and rail yards
74
8140
Roads and Highways
83
8310
Electrical Power Facilities
27
'8330
Water Supply Plants - Including Pumping Stations
27
With regards to the slope of a basin, due to the nature of the typically flat topographic
features found in the City of Miami, it was determined that calculating an average slope
based on the entire sub -basins slope values would provide a representative value. The
slope of each sub -basin was calculated using ArcMap's Spatial Analyst extension and
the DTM prepared for this project. Steeper resulting slopes will produce a higher peak
hydrograph and conversely a flatter slope will attenuate the runoff peak.
Table-6-3-provides-a-listing-of the physical-sub-basin-,attr-ibu.tes defined -for -.the NBB
and SBB models.
6-8
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
Table 6-3 - Sub -Basin Physical Attributers
' Tr y ...'l
SufBasin
Area1
, (ac)=
`'Percefirt npe-rvio- rri,
..:..� ..,,(./0)_4? .�,.
Width
s. .x.s ..(ff) .,...(ftlft)r
Slope-
•,.
SB01
321.3
70
2470.6
• 0.005
SB02
190.3
69
6816.1
• 0.009
SB03 -
70.8
70
728.7
0.005
SB04
483.0
70
5232.2
0.004
S B05
133.7
68
1730.1
0.006
SB06
337.0
70
2946.8
0.004
SB07
127.6
68
1996.9
0.007
SB08
61.5
72
1461.6
0.005
SB09
251.8
70
2200.5
0.003
SB10
236.7
71
3393.2
0.003
S B 11
89.0
72
1595.1
0.004
S B 12
77.4
72
860.8
0.004
SB13
186.2
73
3035.2
0.003
SB14
166.4
71
2689.8
0.004
SB15
121.2
72
1706.6
0.005 '
SB16
116.6
71
1954.7
0.003
SB17
256.1
73
3709.9
0.003
SB18
355.2
57
3182.4
0.008
SB19
131.1
• 72
2475.5
0.003
SB20
166.7
71
3871.2
0.004
SB21
195.2
71
3018.5
0.003
SB22
4.1.2
71
718.0
0.004
SB23
435.3
70
11040.1
0.004
SB24
119.8
67
2181.5
0.005
SB25
346.1
71
3714.8
0.003
SB26
225.4
71
3165.3
0.003
SB27
94.1
69
1353.0
0.004
SB28
187.6
72
1565.5
0.003
SB29
95.5
72
1638.1
0.003
SB30
172.9
71
3583.9
0.005
SB31
80.1
72
1435.1
0.004
S B 32
_7.0 .. . .. ....:.........
__..3223 9
___0 012 _
_.__ _
SB33
.-._..157.3 .._..
525.5
71
3561.4
0.004
SB34
226.3
71
3218.1
0.005
. SB35
43.1
70
1086.9
0.006
SB36
75.7
64
1719.5
0.005
SB37
26.9
78
596.9
0.029
SB38
191.4
72
4916.2
0.01
SB39
141.0
68
2316.2
0.008 •
NB40
30.1
53
949.8
D.017
NB41
62.2
66
2031
0.012
NB42
60.4
77
1624
0.018
NB43
42.9
72
1007.7
0.01
NB44
124.2
68
4121.4
0.009
18153
0:009
N645
7272
02
NB46
131.6
69
2607.5
0.029
NB47
111.9
68
1570.2
0.008
NB48
71.2
75
1687
0.004
NB49
174:3
71
3473.5
0.014
6-9
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
,' , r '
>Sub -Basin,
" '°Ara Yap
r(a)z,•A,r��'�-
,ercentklmpery ous
et'e:.r(/o) qi
t Widthh ,_
:: :; x.,.
Slope '
,f).�x..
NB50
85.9
74
1054.5
0.021
NB51
68:8
54
1823.9
0.016
NB52
62.6
73
2150.5
0.006
NB53
36.8
82
315.5
0.029
NB54
176.2
69
2316.1
0.011
NB55
140.4
81
2981.1
0.004
• NB56
82.5
74
3128.6
0.009
NB57
46.9
78
1024.8
0.056
NB58
147.5
71
2253.7
0.005
NB59
192.9
76
2655.5
0.005
NB60
79.1
77
703.7
0.032
NB61
69.6
73
949.1
0.005
NB62
47.5
79
488.
0.044
NB63
32.1
71
4016.6
0.007
NB64
133.9
71
2983
0.005
NB65
90.2
73
1720.9
0.007
NB66
182.6
71
3169.2
0.005
NB67
68.4
74
1687.8
0.012
NB68
50.9
74
729.7
0.008
NB69
125.1 •
72
1650
0.005
NB70
131.8
71
1362.1
0.008
• NB71
97.7
69
889.5
0.006
NB72
37.1
72
1072
0.005
NB73
130.7
72
2594
0.01
NB74
28.5
67
452
0.004
NB75
73.8
70
1705
0.004
NB76
110.2
72
1816.4
0.005
NB77
79.3
71
1298.4
0.004
NB78
41.4
71
1112.4
0.016
NB79
39.2
74
1795.1
0.007
NB80
89.0
71
1231.3
0.005
NB81
155.1
60
2791.8
0.007
NB82
283.0
74
1340.6
0.006
NB83
84.2
70
1868.1
0.01
NB84
126.8
70
1176.7
0.005
NB85
50.9
60
1425.5
0.007
NB86
35.3
71
840
0.008
N587
68.8
72
1105.1
0.007
NB88 •
20.6
79
902.8
0.004
NB89
108.0
71
2137.7
0.006
NB90
23.4
71
1733.5
0.01
NB91
90.6
72
1903.4
0.003
NB92
95.1
72
1315.8
' 0.006
NB93
43.5
75.
966.7
0.006
NB94
64.2
71
1561.1
.0.006
NB95
37.9 •
71
921.5
0.008
6.1.3 Groundwater Infiltration
In the DERM canal basin models, groundwater seepage from the upland basins to the
canals was speculated to be a significant flow contribution. XP-SWMM allows the
6-10
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
transfer of infiltrated water as groundwater from a basin to a canal runoff basin. This
feature was not utilized in the City Phase II models. This feature was unnecessary
because no canals or rivers exist within these coastal basins and the control of flow in
and out of sub -basins could not be further manipulated by this feature. In addition,
accounting for infiltrated groundwater becomes more critical for simulating long -duration
events (month or a year) - long -duration events are not being evaluated as a part of
Phase I or II.
6.1.4 Rainfall
In order to calibrate and verify the XP-SWMM models, simulating large, recent rainfall
events were desirable. Recent years are desirable because of the availability of
calibration data, both anecdotal and recorded, and the more recent static nature of the
subject basins in terms of development and land use. Both the NBB and SBB have
undergone little change over the last decades primarily due to the built out nature of the
City.
Log -Pearson Type -III frequency analyses of the maximum 1-day and 3-day rainfall
events were calculated for all rainfall totals from 1939 to 2010 for the long-term rainfall
station at the Miami International Airport. Although notable rainfall events were found in
•years 1942, 1979, 1991, and 1992, the age of these events were not ideal in terms of
available calibration data and verifiable City flood records. From the information shown
in Table 6-4, the years 1999 (Hurricane Irene) and 2000 (No -Name Storm) events are
the most appropriate in meeting the recent data and rainfall magnitude criteria. The
Hurricane Irene event was a 5-year frequency event for the 1-day duration, which is
also the frequency for one of the design storms. The frequency for the No -Name Storm
event also approaches the 100-year frequency event rainfall depth.
Table 6-4 — Notable Historical Rainfall Events
{K
,Y rr
1da
7.Recurrenee
I
_ 3 day s
Recurrence
'nterval
`" a
..:Rnch s1)*
f( )
y ea s
(-y ) Y 4
i�4aches
t( )
i4 (years)'
>100
1942
12.58
50
19.39
1979
14.85
100
16.24
62
1991
6.76
6
12.76
22
1992
6:61
6
8.12
5
4999 *
:.:.,. 5 56
... _ S :
_.: ;1;0 99 . s
' , : 12 ,._.:
2000
;, 12:4.8;4
52
,. _^.15 3 ..'<
.. .46 •!iirl
Based on this rainfall analysis, the years 1999 and 2000 events were used to calibrate
and/or verify the resulting models. The 1999 event will provide a 5-year event for the 1-
day duration and a 12 year event for the 3-day duration; whereas the 2000 event will
provide a 52 year event for the 1-day duration and a 50 .year event for the 3-day
duration. For both the 1999 and.2000 events, rainfall data was taken from node C6-S17
if the DERM C-6 model. This node referenced Rainfall File # 40721, for both the 1999
and 2000 events.
6-11
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
As is typically done in South Florida, design storm distributions were taken from
SFWMD data (South Florida Water Management District Environmental Resource
Permit Information Manual Volume IV .2006). Design storm rainfall depths obtained
from SFWMD isohyetal maps varied between the NBB and SBB model domains. The
rainfall depth for the 5-year, 1-day design storm was 6.0 and 6.5-inches for the NBB and
SBB, respectively, and the rainfall depths for the 100-year, 3-day design storm was 14.0
and 15.5-inches for the NBB and SBB, respectively.
These rainfall depths were reduced using the rainfall extraction method described
previously in Section 6.1.2 for sub -basins with exfiltration trench BMPs. With this
methodology, the distribution rainfall file and depth were maintained the same for all
sub -basins, with only the extraction amount taken from the total rainfall to account for
exfiltration trenches.
6.1.5 Groundwater Elevations
Since there are no surface water stations measuring stages or flows originating from
both the NBB and SBB, the two groundwater stations described in Section 6.1.5, were
used in the selection of the initial conditions for calibration models — the plotted stages
are shown in Figure 6-3 and Figure 6-4. The peak groundwater levels for these storms
at Station F-179 in the North Biscayne Basin occurred on October 15, 1999, and *on
October 4, 2000. The peak groundwater levels for these storms at Station F-45 in the
South Biscayne Basin occurred on October 16, 1999, and October 4, 2000. Initial
conditions were set using the `ZREF' configuration parameter in XP-SWMM, with the.
1999 event ZREF being defined as 2.54 ft-NGVD for the North Biscayne Basin and 2.78
ft-NGVD for the South Biscayne Basin, while the 2000 event ZREF values were defined
as .2.73 ft-NGVD for the North and 2.45 ft-NGVD for the South.
For the design storm event runs, the typical high groundwater elevation was used based
on the Average October Groundwater Level Map from the Miami -Dade County Public
Works Department. This value was set at elevation 2.0 ft-NGVD using the ZREF global
parameter-for.allsub-basins. This_value -was used.because_of_the..coastal_nature of the
majority of the sub -basins within the NBB and SBB and "the relatively minor variation
between basins throughout the limits of the Phase II models.
6-12
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
10
8
6
> 4
w
J
6-
Groundwater Level at Well F-45 and F-179
October 1999 Calibration Period
09/07•'99 09/17/99 09/27'99 10/07/99 10/17/99 10/27/99 1106/99
Date
—F-179 South Biscayne —F-45 North Biscayne
Figure 6-3— 1999 Groundwater levels for Stations F-45 and F-179
Groundwater Level at Well F-45 and F-179
October2000 Calibration Period
9
a i
9
1
L 6
-I•
N
J
f0 i
.2
0 !
D
09/01/00
09/11/0D 09/21/00 10/01/00 10/11/00 10/21/00
Date
—F-179 South Biscayne
10/31/00
—F-45 North Biscayne
Figure 6-4 — 2000 Groundwater levels for Stations F-45 and F-179
6-13
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
6.2 Hydraulics Block 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 responsible for interbasin transfers 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 those models were to implement projects with
County funding.
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
4 Natural channels for the open channel reaches and overland flow connection
between adjacent basins
No secondary stormwater management systems were defined or simulated in the
models unless a system served the purpose of conveying runoff from one sub -basin to
another. Self-contained systems were mostly ignored for this reason. The following
items were generally noted regarding DERM's models:
• Sub -basin stage -storage relationships were developed using GIS and the DTMs
created for each sub -basin.
• Overland connectivity between adjacent sub -basins was simulated using natural
channel conduits.
• Channel cross sections were obtained using GIS and the developed DTMs.
'The initial groundwater depth of each junction was established -based on -the
average October groundwater elevations or the historical stage.
The endpoint junctions of each model network were simulated as outfall junctions and
defined the boundary conditions of the models. The outfall junctions used by DERM
included Free Outfall, Fixed Backwater, Tidal Series, Stage -Discharge relationships, or
Time -Stage relationships. One set -of -boundary conditions--were-used-fore-calibration ---
based on measured data and another set was used to simulate design storm event
conditions.
For the City of Miami Phase II models, a variation of the methods used by DERM were
carried over as part of the methodology for model development. With these items noted
in the DERM models, the following subsections describe the major components of the
hydraulic network for the City of Miami Phase II models.
6-14
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
6.2.1 Setup of Hydraulic Node -Link Schematic
The hydra,u.lic network of a system defines the relationships between nodes in a
stormwater management system, Some of these links are man-made and intentional
connections between and through sub -basins, while others can be naturally occurring.
'Some of these man-made connections include conveyance systems made up of items
such as pipes, trenches, pump stations, and canals. Some of the naturally occurring
connections include lakes, rivers, as well as some items that may not be as obvious
such as low points along abutting sub -basin boundaries. These links become the
hydraulic network of the model and is the method for sub -basins to discharge or receive
runoff from adjacent sub -basins or bodies of water.
Within the XP-SWMM, runoff can only be routed between sub -basins when a link is
predefined to exist between nodes, The hydraulic network for the system was
established based on known drainage infrastructure using the City of Miami GIS
stormwater atlas as well as the scanned stormwater atlas sheets provided by the City.
The nomenclature utilized for the hydraulic network is as follows:
• For links between sub -basins, the from and to node name is used separated by
an underscore, i.e. SB3O_SB29.
• For links between a sub -basin and an outfall or boundary condition, the from
node name is used followed by "_OUT", i.e. SB29_OUT.
For intermediate links that do not apply to the above, the residing street name
was used for the link name, i.e. GateLn2.
The hydraulic network for both the NBB and SBB are presented in Attachment E. The
following sub -sections further describe the different parameters used in the models to
simulate the City of Miami's drainage systems.
6.2.2 Hydraulic Nodes
In XP-SWMM, hydraulic nodes represent the storage elements of a stormwater
management system. These locations are where observing a stage in the system is
desired, where several links branch off in a system, or where a boundary conditions in
the model exists. Runoff and groundwater flows are passed to hydraulic nodes which
then either store the water or route the water to links, based on hydraulic head, and
then to a final point, typically an outfall (boundary condition). There were three major
types of nodes used to simulate the City of Miami systems which included:
• Storage Nodes: These are the primary nodes that simulate the physical
attributes if a sub -basin. These nodes represent the same
element as the Runoff nodes. They receive runoff flow,
store and attenuate this flow, and discharge this flow if they
cannot store it based on the connectivity conditions.
6-15
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
• Junction Nodes: These nodes represent locations where pipe sizes change
within a system, where several links branch to and/or from
another node, and locations where peak stage observations
are desired.
• Boundary Node:
These are nodes where a boundary condition is set. These
include the Biscayne Bay high water elevations or a time -
stage condition derived from an adjacent model where an
interchange of flows could occur.
6.2.2.1 Storage Nodes
These nodes represent the physical storage capabilities of the nodes that were defined
in the Runoff Biock that generate the runoff and groundwater hydrographs. Runoff
passes through these nodes and either store water, attenuate flow, or function as a
reservoir that provide flow via a link. A detailed stepwise linear storage relationship was
defined at 0.1-ft intervals and was developed using the DTM in GIS using Spatial
Analyst. The XP-SWMM Model converts the defined stage -area relationship into
volume for use in the internal equations. The special configuration parameter "AE" was
used in the City models in order to define the stage -area relationship as an elevation
rather than the default depth -area relationship in the Hydraulic Block.
The special configuration parameter "ZREF" was also used, which defines the initial
stage for all Storage and Junction nodes in the Hydraulic Biock . The defined values are
as described in Section 6.1.5, where the values for the calibration and verification runs
were based on historical values and the design event runs were set at the average
October water elevation. Additionally, the runoff nodes spill crest elevations were set
well above the anticipated peak water levels. This was done so that water is not lost
from the system and is stored in the sub -basins.
6.2.2.2 Junction Nodes
Junction nodes represent major or critical locations in the pipe systems where
conditions such as pipe size changes are realized, where multiple links branch from a
specific location, or where a stage observation is desired within the drainage system.
No stepwise linear stage -area is defined for these nodes and the default junction area
equivalent to a 4-ft diameter manhole is used. A spill crest elevation in excess of what
is expected to be realized in the model was defined for these nodes.
6.2.2.3 Boundary Nodes
Both of the models developed for this SWMMP have a combination of outfalls to
Biscayne Bay or Miami River and where flows interchange with an adjacent sub -basin
represented in the DERM models exist. For all outfalls to Biscayne Bay or the Miami
River, a User Stage History was defined based on a sinusoidal tidal elevation for the
design storm events and historical stage data for the calibration and verification events.
6-16
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
Hurricane Irene (1999) and the "No -Name Storm" (2000) both had unique tidal
conditions. These two conditions were derived from the Virginia Key (Bear Cut) tide
station and were simulated in node C6-19 in the DERM C-6 Basin model. Figure 6-5
and Figure 6-6 provide a graph of the historical stage data coded into the model to
represent the tidal conditions at all outfalls for the calibration and verification models.
Additionally, a review of both the 5-year, 1-day and the 100-year, 3-day design storm
event models from DERM showed a single tidal boundary condition set for all outfall
nodes in both models. These three conditions were carried over into the City of Miami
Phase II models for inclusion into the tidal boundary conditions. Figure 6-7 provides a
graph of the sinusoidal stage data coded into the model to represent the tidal conditions
at all outfalls for the design storm event models.
oe. L.�+ � f `s } I l+ili��.. -`. .1' ii', CC ..
�iItjvf" i..,tJ.,..:>rJx ft✓). ... 1...+. ,eri R�.. �.-I.i�...a': Akr i? F.... .
{x a0 i '1 h
VI .. »: «�..n �1a*x
.;
.:,brN <
t
. 5.0
4.57
4.0
3.52-
?3.0_
1.0.��....._.\.........1_....
0.0—�.
0
lI
V
Iv
11
- 1.`1.._1
1 l
t
I
'
7
}
/ ; !
..._ 1,:...-
;,
-T---
d a�
t/
r
20 40 60
80 100
Time (hr)
120 140 160
Figure 6-5 — Hurricane Irene tidal data graph
#G h c x `}`t x sk xs^ti•.
RE i ga mml t ' .. a.,�
. gl
1 p
.....
3.0-
.
!
..... ..\ ....
1H11
I
I ti
I\ I
i .1...i. ..... 1,...
' y
{V
' 2.5
• 'Fr.•
0.5
-[
0.0}
I
j
�11
1
1!
fi1
I
t
/1
fII
li
1�
'
r
"
I I
� f
1
r�
r
i
0 20 40
60
....
80 100
Time (hr)
120 140 160
I ..:'^,1AWiDore e`HN?AhY%1.
Figure 6-6 — No -Name Storm tidal data graph
6-17
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
20 40 60 • 80 100 120 140 160
Time (hr)
Figure 6-7 — 5 and 100-year Design Storm Event tidal data graph
In addition to the tidal boundary conditions described, a few sub -basins required a
connection via a pipe to an adjacent DERM model. A number of locations were
identified where a boundary condition could be defined from the DERM 'models. Table
6-5 provides a listing of the nodes sourced from the DERM models for the purposes of
providing a time -stage boundary condition. Unique time -stage boundary conditions
derived from the applicable DERM source models were defined for each of the
boundary conditions in both Phase II models — i.e., Hurricane Irene, No -Name, 5-year,
and 100-year models.
Table 6-5 — Boundary Conditions
.,' € Phasefll '<
,Model:Node'Name<..,_ ,
a DERM}Model Node ;
,.. Usedrfor,.B• oundaryyCondltion =,..,
SB20_OUT
C5-S6-1
SB34 OUT
C6-S-18
SB37 OUT
C6-S-19
NB46 OUT
N6-C6-E-2
NB49_OUT
N6-C6-E-2
NB57 OUT
CC6-N-13
NB63 OUT
CC6-N-11
NB68_OUT
CC7-S-25
Instances where a time -stage series was incomplete for the duration of the simulation,
the time series was extended to the end of the•simulation. This was accomplished by
repeating previous data where the repetition was consistent with the data being
appended.
6-18
February 2012
6.2.3 Links
City of Miami
Phase II - Stormwater Management Master Plan Final
Links convey the flow between the various nodes defined in the drainage system.
These links can represent pipes, trenches, channels, canals/rivers, pumps, weirs, and
natural weirs. In the NBB and SBB models, channels, canals/rivers, pumps, and weirs
did not exist. For the City of Miami Phase II models, two main types of links were used.
These links included:
• Overland Flow Links
• Pipe/Trench Links
These links were the primary stormwater management systems controlling flow and
stages within the limits of the Phase II basins. The following subsections describe how
the different types of links were utilized.
Although one pump station does exist within the Phase II limits - the Overtown Pump -
Station location at 1515 NW 5th Avenue - this pump station has been out of service for
some time and is not scheduled to return to service within the foreseeable future based
on discussions with City staff.
6.2.3.4 Overland Flow Links
Overland flow weirs were defined where critically low area exists and where interbasin
transfers were possible, resulting in runoff being exchanged between sub -basins via
overland flow patterns. Using the DTM and GIS tools such as Spatial Analyst, profiles
were derived at specific boundaries. These overland weirs ensured that interbasin flow
was not restricted by the total capacity of the existing stormwater management systems
implemented in the models.
These cross sections essentially become natural channels for overland flow to be
conveyed through. The cross sections vary in width, although most exceed .1,0004t in
length. Additionally, each_naturalcross .section was.given a defined length of 50-ft, to
not create instabilities within the model - this value was also used by DERM in their
models. Cross section slopes were all calculated to zero, by assuming a reasonable
value for the upstream and downstream elevation (the value of the lowest elevation
point along the cross section). This was done to ensure there was no hydraulic
influence across the cross-section as it is meant to represent low points along sub -basin
connections. Flow was exchanged between basins when the lowest elevation of the
overland flow weir was exceeded. A roughness coefficient of 0.04 was used for all
cross sections in keeping with similar values used in the C-6 model. Figure 6-8
provides an example of an overland weir represented as a cross section for inclusion
into a link as a Natural Section.
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
iNawral3ectiun3hape 3821.,
1:1#13fl a trfki;&i` Jifc e
E''':l 3043.772 1234756
€ 3068.099 :1125827
3092327 :11_50382_
'':1j 3116b04 '1142766
t '(4 3190.861—11.44281
J 3160.159 :N .44186
3190.121 31.45289
3215.084---'11.55761
�;�13240.047--'11.63605
3265.010 11.67311
3289.973 11.67895
',. 3314.936 11.64903 i
3340 '11.62830
Lat:DverbafJc4>I0.9
c R'pt;l' Dvei.ier.1 3340.
LeltOverhank_ 0.04
dh:
GiepFi'Moje
Centeirhnnnel4 0.04
Aiiit•Overli ..,.:I0.04
Figure 6-8 — Sample cross section input for overland weir
6.2.3.5 Pipe/Trench Links
The pipe networks were derived from the City's GIS coverage and supplemented with
Geo-Referenced Atlas sheets. The Atlas sheets provided pipe dimensions and shapes,
where available, and assumptions for pipe sizes were made when no information for a
system was available based on upstream/downstream infrastructure information.
For all of the City's systems, no pipe inverts were provided. Therefore the inverts.of
pipes were assumed by subtracting 3-feet of cover and the pipe diameter from the
topographic elevation at a junction. Where invert elevations seemed unreasonable due
.to topographic_high._points., _pipe_inverts were adjusted_to_an_appropriate_elevation to
maintain a proper slope within the system with the presumed flow direction. The
resulting conduit slope was calculated within XP-SWMM, from the Upstream and
Downstream invert elevations of individual conduits derived from this process.
Similarly, conduit lengths were calculated in GIS based on the provided GIS coverage.
6.3 Model Calibration & Verification
The completed XP-SWMM models were run and result data was extracted from the
individual models. Table 6-6 provides a breakdown of the model efficiency and error for
the four simulated events for the two major coastal basins. Overall, the models ran
efficiently with very small continuity errors. XP-SWMM gave the models and overall
rating of "Excellent" based on its own grading criteria.
6-20
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
Table 6-6 — Model Efficiency and Errors
' S ,t{ -c, �'xsk ax dn--t,,--
; � Y'
r -. odel;r .,
'1' ' yX'r
vent , __,
E r
y, k�''8 h.
Cont nu
zErrort �.
:' 47..,�•'rs"s�,�"5..a.£ d,
�Y� °
:y K'/0: ^7 . lx d »
erall Error
th ff�
;s eSimulation
. %
.., .,,c;... °,,,, �+z..=,:
p
Ratingn, :.
North Biscayne
Irene
-0.0182%
2.43
0.0174%
Excellent
North Biscayne
No-Name
-0.0239%
2.28
0.0199%
Excellent
North Biscayne
5-Year, 1-Day
0.0098%
2.29
0.0098%
Excellent
North Biscayne
100-Year, 3-Day
-0.0087%
2.23
0.0076%
Excellent
South Biscayne
Irene
-0.1429%
2.04
0.0825%
Excellent
South Biscayne
No -Name
-0.0535%
2.05
-0.0535%
Excellent
South Biscayne
5-Year, 1-Day
-0.0782%
1.99
0.0419%
Excellent
South Biscayne
100-Year, 3-Day
0.1743%
2.09
0.0394%
Excellent
Calibration of the XP-SWMM models was performed using a anecdotal data due to the
absence of measured stage, flow, or runoff volume data for canals, streams, rivers, or
lakes within the City's two coastal basins. These are generally the locations where
stage and flow data are gathered and where comparisons for calibration can best be
performed. With no data to compare model results with observed conditions, calibration
depended upon comparisons to historical flood plain data, repetitive flood insurance
loss data, and input from the City in the form of known flooding areas. Calibration for
these models was performed by adjusting the Max Infiltration Rate (F.) under the
Horton Infiltration parameters until acceptable runoff rates were realized in the model
results.
Model results were also checked for instabilities by selecting individual links and
evaluating the static and dynamic graphs for pipe flow and stages. In conditions where
flows or stages seemed unreasonable, minor adjustments, which only included
adjusting the invert of pipe links, were made until the results stabilized.
The following subsections provide a description of the comparisons performed for the
purposes of verification of the model results. Attachment F and Attachment G provide
-a-summary-of-the -result-data-for,this phase of -the -model -development, process -for -both
basin models for the Hurricane Irene and the No -Name Storm event, respectively.
6.3./ Repetitive Flood Loss Comparisons
FEMA provided the City with a listing of the properties experiencing repetitive flood
losses for a 20-year period. Losses in the database range from a date of loss of August
24, 1992 to June 23, 2009. This historical claims database was geocoded based on the
provided street addresses and compared to the Hurricane Irene and No -Name storm
event flood plains developed from the model.
This type of comparison provides a general description of the extent of flooding
experienced within an area but also has numerous limitations. The primary limitation is
the fact that not all homes are covered by flood insurance and not all homeowners
report claims in the event of a loss. This diminishes the total number of comparison
points available. Conversely, there are also site specific conditions which can also
6-21
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
contribute to localized flooding resulting in repetitive losses to a property but that do not
present themselves in the resulting flood plains controlled by the primary drainage
system. This is mainly due to the fact that secondary drainage systems are not
modeled in planning -level studies such as this one. Finally, some homes were built to
substandard requirements due to their age. Current building codes are considerably
more strict today than they were many decades ago, which is true for many properties
within these coastal basins.
Figure 6-9 through Figure 6-11 provide a sample of the comparisons performed for this
process. These figures present the flood plains for the Hurricane Irene and the
No -Name storm events. The No -Name storm event had more extensive flooding than
what was experienced under Hurricane Irene. The extent of flooding is presented by
showing the Hurricane Irene flood plain limits in red and by further extending the
Hurricane Irene flood plain in yellow to the No -Name storm flood plain limits.
Additionally, the repetitive loss properties are shown for losses attributed to Hurricane
Irene, the No -Name storm, and all others in black, green, and blue, respectively.
The comparison performed for this project showed areas with good correlation between
losses and derived flood plains. Coastal areas are shown to have a significant number
of reported losses which correlates well with the resulting flood plains. As was
expected, there were numerous areas where sporadic flood loss claims were present
which did not correlate with the resulting flood plains. For the most part, areas where
groupings of flood losses are present generally fall within the resulting flood plains.
6-22
February 2012
City of Miami
Phase II Stormwater Management Master Plan Final
pp.
.07174.
Legend
All other Losses
Irene Losses
ice? No Name Losses
Irene Flood Plain
0
Flood Plain
Non Name Storm Flood Plain
0
Ij Flood Plain
,;Rep_etitive losses _ _
flood plain correlation
Rep.etitiv.e losses &'
ala:od;plain correItion
Figure 6-9 — Repetitive Losses compared to Hurricane Irene & "No -Name" storm simulated flood plains.
6-23
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
9 A9 F14'tl.. "sr .�'.
13-7rrteXto
:
I! Yt4 • ,a,i-
Figure 6-10 — Repetitive Losses compared to Hurricane Irene & "No -Nary e" storm simulated flood plains.
6-24
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
Repetitive Iosses &
.floo.d s lam correlation.:':_
Figure 6-11 — Repetitive Losses compared to Hurricane Irene & "No -Name" storm simulated flood plains.
6-25
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
6.3.2 FEMA Flood Plain Comparisons
A comparison was also performed against the. FEMA. Flood Insurance Rate Map Flood
Plains. FEMA maps the 100-year flood plains which should correlate with the flood
plains developed for the 100-year design storm event. The FEMA zones associated
with the 100-year flood plain are Zones A, AE, A1-30, AH, AO, AR, A99, V, VE, and V1-
30. Figure 6-12 through Figure 6-14 provide a comparison between the FEMA flood
plains and the derived flood plains from the 100-year model. It was noted that large
areas within the North and South Biscayne Basin were designated as Zone X in the
FEMA GIS coverage. Zone X is described as follows on the FEMA Definitions of FEMA
Flood Zone Designations web page:
"Area of moderate flood hazard, usually the area between the limits of the
100-year and 500-year floods. B Zones are also used to designate base
floodplains of lesser hazards, such as areas protected by levees from 100-
year flood, or shallow flooding areas with average depths of Tess than one
foot or drainage areas less than 1 square mile."
Because of this designation, large areas were shown to be outside of the FEMA flood
plain. For comparative purposes, the repetitive loss properties were also shown in
Figure 6-12 through Figure 6-14. These areas do show some repetitive loss history
and it is undetermined what the reason is for these areas to be outside of the FEMA
flood plains.
6-26
February.2012
City of Miami
Phase II - Stormwater Management Master Plan Final
,Legznd
All other Losses
Irene Losses
FEMA_Flood_Zones
1-7 Outside Flood Plain
FLD_ZONE
?,r7�t` ,l Zones AE, AH, & V E
100-Year Flood Plain
<VALLiE>
1A floor! R:IIn
100-year_flood lain °correlation
Figure 6-12 — FEMA Flood Plains and 100-year storm simulated flood plains.
6-27
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
-Legend
All ocher Losses
•
•
Irene Losses
IVo Name Losses
FEMA FloodZones
FLD .ZONE
'',41,41 ZonesAE, AH, &VE
100-Year Flood Plain
ai,. FEi'VIA`Flood Plaln &;
�' 1'00 ye.at flood plain correlation
FEMA F1o:od Plain &
1 D0 yaar flood .plain coi relation:
Figure 6-13 — FEMA Flood Plains and 100-year storm simulated flood plains.
6-28
City of Miami
Phase II - Stormwater Management Master. Plan Final
February 2012
Outside Flood Plain
FLD_ZON E
f+'l� ZonesAE, AH, &VE
Figure 6-14 — FEMA Flood Plains and 100-year storm simulated flood plains.
6-29
February.2012 City of Miami
Phase II - Stormwater Management Master Plan Final
Attachment V. provides a map showing the FEMA flood zones overlaid on top of the
flood plains developed under this SWMMP update.
6.3.3 Known Flooding Area Comparisons
Maps showing areas where recurring flood complaints have been reported were
provided by the City for comparative purposes to the result data. Although these maps
did not include the date of the recorded complaints, these maps were used to compare
flood plains to real world conditions for both the Hurricane Irene and No -Name storm
events. As with the FEMA repetitive loss database, this data source can provide a
relative understanding of the flood problems within the City although the data can be
inconsistent and sporadic. in nature due to the reliance on communication from the
residents and business owners.
The City provided map, a 36" x 36" scanned and hand annotated document, was
compared to the resulting flood plains. Some correlation was observed between the
City map and the Hurricane Irene and No -Name storm flood plains. The flood map
showed areas of recorded flood complaints primarily within the South Biscayne Basin.
These areas helped verify the existence of areas of concern with regards to regular
flooding. Although the previous is true, the coastal repetitive loss properties found in
the FEMA database did not present themselves in .the City map. It is unknown why
these repetitive loss properties are not a part of the City's logged complaint data.
In general, the areas showing concentrated flood complaint data tended to fall within the
resulting flood plains from the models. Additionally, as with the FEMA data, additional
areas of complaints were also observed where the complaint data fell outside of the
flood plains — possibly due to localized deficiencies within the City systems generally not
captured within planning -level models such as these. In general, more often than not;
the flood complaint data agreed with the resulting flood plains, with the exception for the
coastal areas mentioned,previously. •
Additionally, the City provided a database of recorded complaints addressed by the
City's Public Works Operations department where City crews were not able to identify a
storm sewer system so the staff forwarded the complaint to the engineering department.
These addresses were geocoded based on the recorded address and plotted over the
5-year flood plains for comparative purposes. The recorded complaint data
corresponded well with the 5-year flood plains with the majority of the points falling
within the 5-year flood plains. Figure 6-15 and Figure 6-16 provide an example of the
correlation described.
6-30
February 2012
Areas with correlation
to:the`flood plains..
City of Miami
Phase II - Stormwater Management Master Plan Final
• City Complaint Data
Irene Flood Plain
no
Flood Plain
No-Nam.e Storm Flood Plain
Flood Plain
Figure 6-15 — City Recorded Flood Complaint data and 5-year storm simulated flood plains.
6-31
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
_Ar..e.as =with :corr..el'atio
to the'.flood plains
0 City Complaint Data
Irene Flood Plain
Flood Plain
No -Name Storm Flood Plain
Flood Plain
Figure 6-16 — City Recorded Flood Complain data and 5-year storm simulated flood plains.
6-32
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
6.4 Existing Conditions/Baseline Model Results
The ..resulting models from the calibration and verification phase of the model
development process were simulated under the conditions defined for the design storm
event scenarios. For this phase of the SWMMP, and in keeping with the Phase I
scenarios, these models were simulated under the 5-year, 24-hour and 100-year, 72-
hour design storm events. The parameters for rainfall, groundwater, outfall, and
boundary conditions were defined in the Runoff and Extran block model setup sections,
as described in Section 6.1 and Section 6.2.2.3.
Attachment H and Attachment I provide a summary of the result data for this phase of
the model development process for the North and South Biscayne Basin models for the •
for the 5-year, 24-hour, and 100-year, 72-hour events, respectively.
6.5 Model Development Conclusion
DERM established a solid basis for the concepts and methodologies needed for the
development of a complete and quantifiably representative hydrologic/hydraulic model.
Methods for calculating stage -areas and defining hydrologic parameters typical to South
Florida, as well as typical assumptions regarding urban stormwater management
systems, were all well documented in the various Miami Dade County Basin SWMMP
reports. These methods and concepts were carried forward to the City SWMMP model
development process, whenever possible and/or viable. The methodologies were
revised slightly to ,account for a lack of available calibration data and due to specific land
and hydrologic features in the City of Miami.
Although calibration of the XP-SWMM models was performed using anecdotal data due
to the absence of stage, flow, or runoff volume data for canals, streams, rivers, or lakes
within the City's two coastal basins, the results appeared to generally correspond with
expected results within the sub -basins. Comparisons to the FEMA flood plains, FEMA
repetitive property loss database, and to the City collected complaint data showed areas
where good _correlation _to .the .preliminary flood .plains_existed
The resulting models developed for this project were both stable with regards to the
internal calculations performed by XP-SWMM as well as justifiable based on the
anecdotal calibration process undertaken. The results obtained from these models
provided a relatively representative and detailed synopsis of the conditions present
within the City. The models also provided for the existing baseline condition for all
comparisons for the future condition models as well as for the development of future
planning -level projects to be defined in later tasks. Additionally, these models will
provide the City with useful planning -level tools that will aid the City in defining future
projects and potential future expenditures, particularly for the development of the capital
improvement plan.
6-33
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
7.1 DERM :Sub -basin Flood Protection Ranking & Flood Protection Level of
Service Procedures
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 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 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 seventy
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.
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)
7-1
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
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)
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 table below.
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.
"FPSS = [4 x E(;) x NS] -+ [4 x E(;q x MER] + [3 x E(;;) x BM] +
[2 x E(;v) 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
7-2
February.2012 City of Miami
Phase II - Stormwater Management Master Plan Final
7.2 City of Miami Sub -basin Flood Protection 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
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 ofiflooding and
aweighing 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
1 D0-year storm event.
2. Principal arterial roads, including major evacuation routes, should ide 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.
7-3
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
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 thefive 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.
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 allvalues, except -the REP indicator.
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, DEM, MER, MCLRS and
REP), 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 applicable
severity indicators.
FPSS = [4 x Ep) x NS] + [2 x E(;;) x DEM] + [4 x E(;;;) x DEM] +
[1 x E(;v) x MCLRS] + [100 x REP]
7-4
February.2012 City of Miami
Phase II - Stormwater Management Master Plan Final
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 FP.SS . 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 ratingby 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.
7.3 Quantifying Methodology for Sub -basin Flooding Severity Indicators
The various flood severity indicators of the FPSS equation outlined in the previous
section 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.
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. 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_rernaining_manageable in
the GIS environment. Individual roadways are clearly visible and general topographic
trends can be seen for all areas within the City see Figure 4-6.
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 (0-3) being
principal arterials or highways and values four through nine (4-9) being collectors or
7-5
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
local roads. This number classification allowed each segment of roadway to be
classified under either the MER or MCLRS severity indicator. ,
Figure 7-1 — Raster. based DEM
Figure 7-2 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
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 7-2. Each segment was broken into individual segments approximately
7-6
February.2D12 City of Miami
Phase II - Stormwater Management Master Plan Final
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 7-3 — 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 7-3. 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 33,000 properties for
Phase II).
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
7-7
February 2012
• City of Miami
Phase II - Stormwater Management Master Plan Final
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 :7_-2._This, r..esulted...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 7-4. 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 7-4—DEM.to.P.oints
The REP parameter, which .represents the 2009 repetitive loss properties, was counted
by joining the points representing the location of the property with the sub -basin
delineation and totaled for each sub -basin - the sub -basin delineation for both the NBB
and SBB are presented in Attachment D.
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 corresponding
sub -basin. 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 orderto process the information
gathered within the tables and arrive at a proper count of the various elements making
up the FPSS. Each table contained data such as sub -basin name, point elevation, and
' 7-8
February.2012 City of Miami
Phase II - Stormwater Management Master Plan Final
other pertinent data necessary for the proper grouping and summarizing of the entities
they represented.
7.4 Flood Problem .Sub -Basin Ranking Results and Flood Protection Level of
Service Results
The flood severity result data was collected under two .scenarios and two storm events -
the 5-year, 24-hour and the 100-year, 72-hour events. Due to the relatively built out
nature of the City, the need for an existing and future land use model was not necessary
as the expected results would vary by a negligible amount (less than 0.02 ft or
approximately 1/4 inch).
Flood plain data for event 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 7-5 shows a sample area of the flood plain mapping developed for this SWMMP
with some transparency added to the raster cells. Attachment J contains maps
showing the location and severity of flooding for the both design storm events modeled
as vvell as the calibration and verification "events. Attachment -M is contained in the
attached CD with the digital GIS rasters of the flood plains presented.
Figure 7-5 — Sample of Flood Plain Mapping Results
The FPSS results for Phase II are presented in Attachment K 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 .
7-9
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
limits .of .the City of Miami. Table 7-1 present the 15 basins with the highest FPSS
within Phase II's North and South Biscayne Basins. It should be noted that the highest
ranked.sub-basin within-the.NBB..is.sub-basin.NB77...which. ranked_.1.6th.in:this..list.
Table 7-1— Top 15 Basins. for the Existing Condition Models based on the FPSS
5ub',Basi
-, ,jSSt . '
OF kR4i k
s, �.
EPLOS
�, � fi
Sub Bas Ds;;
SB09
8959
1
E
SB09
SB06
7420
2
D
SB06
SB25
7383
3
E
SB25
. 5B23
7081
4
D
SB23
SB10
5305
5
E
SB10
SB04
3834
6
E
SB04
SB30
3376
7
D
SB30
SB13
3321
8
D
SB13
SB14
3241
9
D
SB14
SB34
3069
10
E
5B34
SB33
2809
11
E
SB33
SB28
2447
12
D
SB28
SB20
2417
13
C
SB20
SB18
2218
14
E
SB18
SB12
2034
15
D
SB12
Additionally, Attachment L presents the ranking results in maps coded by their
respective FPSS rank.
Table 7-1 and Attachment L 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.
7.5 Flood Protection Ranking & Level of Service Conclusion
The South Biscayne basin flood plain map shows large areas of flooding primarily north
of the coastal ridge that follows the coast. This area is serviced by a number of large
outfalls which convey stormwater runoff north to south eventually discharging into
Biscayne Bay. Additionally, for both the North and South Biscayne basins, the coastal
sub -basins show areas of flooding due to their low topographic elevations.
The ranking procedures were then applied to the Phase II sub -basins. Utilizing flood
plain data derived from the models in GIS and the topographic data, the ranking
procedure developed by DERM can then be easily applied and provide consistent
results. The additional parameters incorporated into the FPSS equation provided
additional items that were consistent with basin flooding and quantifiable using result
data derived from XP-SWMM and using GIS tools.
7-10
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
The results .and rankings detailed are 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 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.
The ranking procedures showed that the majority of the sub -basins showing the worst
flooding were in the South Biscayne basin. The ranking is primarily driven by the
number of properties flooded although the number of properties flooded is derived from,
and a function of, the total area flooded within a sub -basin. Additionally, although the
number of repetitive loss properties was given a high scoring multiplier, the total number
of properties within in sub -basin was easily superseded by the number of flooded
structures.
With regards to the FPLOS, few sub -basins were scored a "B". The vast majority of the
sub -basins scored either "C", "D", or "E". This was expected given the extent of the 5-
and 100-year flood plains derived from the DEM and the XP-SWMM result data.
Additionally, the ranking procedure showed that the top 15 ranked sub -basins resided in
the South Biscayne basin. This can be attributed to both the extent of flooding in these
sub -basins and the overall size of the contributing area to these sub -basins.
7-11
February.2012
City of Miami
Phase II - Stormwater Managernent'Master Plan=Final
PR!
JE
Thee -following. --subsections summarize the -flood -protection--projects- included ---in- the
Construction and Under Design model -scenarios that were developed under'this portion
of the study. Aside from the 39 projects evaluated under Phase I of .the SWMMP, the
City of Miami also provided project information for a total of 11 projects falling within the
limits of Phase II. During the development -and initial categorization performed under
Phase I of the SWMMP, these projects fell into one of four categories - Constructed or
Under Construction, Under Design, Outside of Phase II SWMMP Limits (Phase I), and
No Drainage Improvements noted. Due to the duration of the two phases of the
SWMMP update process, all of the projects where data was collected and their
components evaluated have now transitioned to the constructed or under construction
scenario - see Table 8-1.
Table 8-1 — Project Status Totals
'1,-;:,:: aStafus „ x; :
h umbe?of P.ro1ects t
74_ MPlielf$.00.1 02
Constructed or Under Construction
10
Construction
Under Design
0
Under Design
Outside of Phase I and II Limits
1
—
No Drainage Improvements noted
0
—
r:- .Totafi ,,ac';`'.. sf M
:r l+ .;.,v;,i> .1a1m- 1: '?f,a z:
The lone project which fell outside of the Phase I and II limits was a project in San
Marco Island which is not part of the mainland portions of the City and not included in
the XP-SWMM- models.
All improvements which fell under the Construction Scenario model were incorporated
into the Baseline Scenario models. The Under Design Scenario required no changes
due to the transition of the Under Design projects into the Constructed or Under
Construction Scenario. For this reason, the Under Design Scenario model was not
developed as a separate model scenario.
8.1 Representation of Stormwater Improvement Projects"in-XP=SWMM
The City of Miami has constructed or was in the process of constructing a total of 10
stormwater improvement projects within the North and South Biscayne basins. 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,
• Exfiltration trenches,
• Drainage wells, and
• Stormwater pump stations.
The major components of these drainage systems were represented in the XP-SWMM
models by either including the location and size of the pertinent drainage component or
8-1
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
by an equivalent rainfall extraction representative of the amount of runoff extraction from
overland -flow to the respective sub -basin - described in detail in the -following sections.
The_pr.ojects..included_in.the...Construction_Scenario. models,..in..addition.:to.the, sub -basins
where these projects provide a stormwater management benefit to, are listed in
Attachment N and are graphically shown in Attachment Q. The revised models and
names used for the Construction Scenario models are files which contain a "_CS"
appended to the digital model file name to denote this specific model scenario.
8.2 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
larger diameter pipes (outfalls or between sub -basins), exfiltration trenches, gravity
• injection wells, and stormwater pump stations. These structural components were then
represented conceptually in the applicable sub -basin within the XP-SWMM models.
As was done in Phase I of the City's SWMMP and as is common with planning -level
studies of this type, internal 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 Biscayne Bay, were represented. The
following sub -sections provide a description of how these stormwater management
structural components were represented in the XP-SWMM models.
8.2.1 New or Increased Pipe Size
One project, B-50690 in sub -basin NB87, replaced existing pipes with larger pipes with
higher capacities for conveying water from one sub -basin to Biscayne Bay. For this
type of improvement, 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__new_ conduit.__in_ the _system...__._In.dividual._.compDne.nts_rep.rese.nting
transfer of stormwater runoff within the sub -basin were ignored.
8.2.2 Exfiltration Trenches
As was done in Phase I, an extraction methodology was used for this SWMMP update,
which assumed that an exfiltration trench in a given system -would -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, This is an accepted
practice used 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.
For this methodology, the total area contributing to an exfiltration trench was based on
the length of exfiltration trench constructed or proposed within a given sub -basin. This
length was associated to a typical width of 320 ft along the length of the exfiltration
8-2
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
trench. The 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-typ.ical._residential area:within_ the City- see Figure
6-2.
Figure 8-1 — Area Attributed to an Exfiltration Trench Length
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 6-1 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 8-2 — Exfiltration Trench Extraction Methodology Example
.''
roaecrt 87 Sub-ban,Atzt
Sub -basin Name = SB10
Basin total area = 236.66 acres
Construction Date = 10/2009
liwie ,3 ibut s '
?,gRi Attnbutedtfo) t
'�Exfiltration7rench� ' �r
h s w, °; .x'•-s
Exfiltration trench length for project = 1,641 If (70% of project total within this sub -basin)
Contributing width = 320 ft
Total drainage area = (1,641 If x 320 If) / 43,560 = 12.06 acres
FAamfal! Ext�rec n h� "
Depth Determmation
% _�
Extraction depth per unit area - 3.28"
Prorated extraction depth = (3.28" x 12.06 acres) / 236.66 acres = 0.17"
Age of Project = 2.1 Years
Reduction % = 2.1 years x 1.0% per year = 2.1%
Reduced Extraction depth = (0.17" x (100% - 2.1%_)) = 0.16"
xzr`"r�
5 bear Rainfall;
SfParamefers ..
,,,N;F�._k- .,, ::,d. _ -
Original 5-year sub -basin rainfall multiplier = 5.81
Ori inal 5 ear sub -basin rainfall depth = 1.0"
9 Y P
Resulting 5-year sub -basin rainfall depth = 5.81"
uRevisedLS{YeaR RRarnfall '"r
Parameters„ °E A4.?
Revised 5-year sub -basin rainfall depth = (5.81" - 0.16") = 5.65"
Revised 5-year sub -basin rainfall multiplier = (5.96" / 1") = 5.65
s
100YearRafnfalb
`4"jiOri
;Parameters`�
, fib. gfri_ 4_11* ; r5 V.
Original 100-year sub -basin rainfall multiplier = 14.81 '
inal 100-year sub -basin rainfall depth = 1.0"
Resulting 100-year sub -basin rainfall depth = 14.81"
t Revised&100 Year ri
aTRalhfallEParameter. "fl:
Revised 100-year sub -basin rainfall depth = (14.81" - 0.16") = 14.65"
Revised 100-year sub -basin rainfall multiplier = (14.65" / 1") = 14.65
8-3
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
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 .8-3 _provides.a_ listing...of_the..total..length_of._exfi ltration_trench.inco.rporated
into the models. Attachment O provides a detailed listing of the extractions
implemented in the model and the basin and sub -basins where these extractions
resided.
Table 8-3---Total Length of Exfiltration Trench incorporated into each Model
sW . O', Basin"' , , xM,
North Biscavne Basin
Languid flE ltratron7rer a tlf)
1,536
South Biscayne Basin
T5,491
' This total is the combined length in both the Construction and Under Design Scenario
8.2.3 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
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 theapplicable sub -basin. Calculation Example 8-4 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.
8-4
February.2012
City of Miami
Phase II - Stormwater Management Master Plan Final
Calculation Example 8-4 — Gravity Injection Well Extraction Methodology. Example
} a -1
ProJeotB.Suba4in .
alnfomtab'
To , ; r
5 4 ;
Sub -basin Name = NB47
"ProB ject#='- --.
Construction Date =2/1991
Basintotal area = 111.94 acres
t`AfealAttribpted',to
;Drainage�Welis .r' j-a. ?s
Contributing project area = 2.20 acres
Water Quality Treatment volume for wells = 2.5"
s °""i
ARemfah Exiacttor ;
i"ieptsDei hemimatidn�
r xtr;;A ? It(100%
Prorated extraction depth = (2.5" x 2.20 acres) / 111.94 acres = 0.05"
Age of Project= 20.8 Years
% Reduction = 20.8 years x 0.5% per year = 10.4%
Reduced Extraction depth = (0.05" x - 10.4 k)) = 0.04"
5 * v'
5 eariet mfalll 4
amters ef .
Original 5-year sub -basin rainfall multiplier = 5.69
Original 5-year sub -basin rainfall depth = 1.0"
Resulting. 5-year sub -basin rainfall depth = 5.69"
J'Revised 3`Year Ramfal141'
V"Paramefers'{` 3 i,;: K
Revised 5-year sub -basin rainfall depth = (5.69" - 0.04") = 5.65"
Revised 5-year sub -basin rainfall multiplier= (5.65" / 1.0") = 5.65
1 0D Year Rarnfall L.
kT ?
Parameters -.. z, ,
Original' 100-year sub -basin rainfall multiplier = 13.68
Original 100-year sub -basin rainfall depth = 1.0
Resulting 100-year sub -basin rainfall depth = 13.68"
il'Revrsed iCO, Year4 s .. e
„Rainfati:Parameters-
Revised 100-year sub -basin rainfall depth = (13.69' - 0.04") = 13.65"
Revised 100-year sub -basin rainfall multiplier = (13.65" / 1.0") = 13.65
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 for an entire sub -basin. In total, 10 injection wells were
incorporated into sub -basins within both the North and South Biscayne Basin models.
Attachment 0 provides a detailed listing of the extractions implemented in the model
and the sub -basins where these extractions resided.
8.2.4 Stormwater Pump Stations
Stormwater pump stations were represented as multi -links with the pump station's
operating conditions defined using the available plans provided by the City. One pump
station was incorporated into the North Biscayne Basin XP-SWMM model.
Attachment C provides information regarding the capacity and operating conditions
used for the pump station as well as a location map for the pump station showing the
relative location of inflow pipes, outfall pipes, and the pump station structure. Table 8-5
provides a listing of the pump station incorporated into the model and its respective total
peak discharge capacity.
Table 8-5 — Pump Stations within the City of Miami
,
.um ;5tatioName
r,sAttachmentc
.. iure�Nubr17-
,f..—.pstream
uub Basit
i—reum"p Stat€bli
aped (GPM
Belle Meade Pump Station
Figure C-1
NB89
44.075
8.3 Basin Hydrologic and Hydraulic Model Setup
The XP-SWMM models representing 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.
8-5
February 2012 City of Miami
Phase II - Stormwater Management Master Plan'Final
The.. following •sub -sections provide a description of wh.at...primary structural drainage
components were ,incorporated into the XP-SWMM models tb assess the flood
.prote.ctiion.._::benefits.-;.o.f__.�sto.rmwater-.. improv...ements__ projects_..._. completed' .and under
construction. AttachmentN provides a • detailed list ofthe-projects" implemented, the
affected sub -basins, the main structural components, and the total extractions or model
parameters adjusted in rthe XP-SWMM models. Attachment Q provides a map of the
sub -basins having projects implemented.
8.3.1 North Biscayne Basin
All changes made to the North Biscayne Basin model's sub -basins consisted of
extractions from exfiltration trenches or gravity wells or pumped flows from a pump
.station. With the exception of the pump station, it appeared that the intent of the
majority of the projects implemented were to reduce localized flooding during minor
rainfall events in areas with deficient existing systems. In total, approximately 1,536-If
of exfiltration trench and eight wells were incorporated into the North Biscayne Basin
model. In addition to the exfiltration trench lengths and wells, one major pump station
was also implemented into the model as well as a project adding outfalls to an area.
Table 8-6 provides a detailed list of these projects, the affected sub -basins, and the
main structural components incorporated into the North Biscayne Basin model.
Table 8-6 — Main project components incorporated into the North Biscayne Model
'
• kPro ectf Number
. SbHbasrn-A
u
Affected �
r �, r*- ,, riot � -k ' NT-.,3u
`; Descaptrontof DrainageT Improueme v4er..
Model Scenarjo
Construction
B-50672
NB89
One 44,075 GPM peak capacity pump station
B-50690
NB87
2 additional Outfalls
Construction
B-5584
NB48
565 LF of Exf. Trench
Construction
B-4521A
NB43
971 LF of Exf, Trench
Construction
B-4521 B
NB47
3 wells
Construction
B-4521B
NB43 i
5 wells
Construction
8.3.2 South Biscayne Basin
All changes -made to the -South *Biscayne Basin model'ss sub=basins consisted —of
extractions from exfiltration trenches or gravity wells. It appeared that the intent of the
majority of the projects implemented were also to reduce localized flooding during
moderate rainfall events in areas with little or no existing systems. In total,
approximately 15,491-If of exfiltration trench were incorporated into the South Biscayne
Basin model. In addition to the exfiltration trench lengths, two wells were also
implemented into the model. Table 8-7 provides a detailed list of the projects, the
affected sub -basins, and the main structural components incorporated into the South
Biscayne Basin model.
8-6
February 2012
City of -Miami
Phase II - Stormwater Management Master Plan.Final
Table 8-7 - Main project components incorporated into the South Biscayne Model
owns {
'ProJectINum6e:ar*Affei
w Sub:basingr
.tedf°,fitr
_ag o t :4;-c ,>r4 . 14
:.�es or4tPt�on of�DrT�na9 tiYlPro �,mw�ajVlodelScenarloy
a , , ., .: .<
• 'B30011.
SB17
703 LF of.Exf:'Trench
Construction •
B-30011
SB10
1641 LF of Exf. Trench
•Construction
B-5660
SB06
4;807 L'F of:Exf. Trench
Construction
B-50685
SB06
8,340 LF of Exf. Trench
Construction
B-50700
SB02
2 wells
Construction
8.4 .Summary of Results and Rankings for Construction .Scenario
The peak stages realized in the Construction Scenario models are .shown in Table 8-8.
u`,b basms;highllghtetlm yellow are sub -basins where. model parameters were adjusted
o 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 mostly minimal reductions in flood stages for the
5-year event ranging from negligible reductions (under 0.1 ft) to a maximum reduction of
1.3 ft. Reductions were smaller for the 100-year event where a maximum reduction of
1.4 ft was shown.
Table 8-8 - Stage Comparison - Baseline to Construction Scenarios (NGVD)
t _ s r
. i 4 a'
Sub basin
' „ 1 . �-
s'1Basetine
,Scenario
itas year
Construction'
- Scenario
i r .5,`,year a
3 Difference -
r '�
, BIVV 5-,years
`4. Scenarios`Q
Caaselme `
c e «'c �
Scenario ��a
100;year
(Construction
' 1. - t
r Scenario
1.00 year
l
R
�° ' 1ffsrence F
Blw4D0 y"earlws
y
42 , See anost .
NB40
4.26.-...
-- -.4126-
- 0.00..
• •6:07
6.07-- .
0.00--
NB41
6.53
6.52
-0.01
6.01
6.01
0.00
NB42
4.26
i 4.26
0.00
6.07
6.07
0.00
-
.NB43.,,
>
e ' • ��
. ,. �7.:68...
� , �3�x,
... ' '7 64 _:
. . D D4��s
� _...8587,��
:�`.�...:8.87..... :�
,.._;�0:00'�„'
NB44
7.68
7.64
-0.04
8.87
8.87
0.00
NB45
5.42
5.41
-0.01
7.23
7.23
0.00
NB46
10.24
10.24
0.00
11.41
11.41
0.00
NB47
3 42 fi
g5,41
0'01
7 23 : ,
. i c 7 23�
:: "t , 0 00
w
,.8B6 „
., i , 48iI85..x.Y -..
.-0.01...4.
,_ 9`T9,
.., .91.9
NB49
10.01
10.01
0.00
12.01
12.01
0.00
NB50
5.13
5.14
0.01
5.93
5.93
0.00
NB51
2.76
2.76
0.00
3.50
3.50
0.00
NB52
11.33
11.33
0.00
12.01
12.01
0.00
NB53
7.85
7.85
0.00
10.30
10.30
0.00
NB54
4.74
4.75
0.00
5.93
5.93
0.00
NB55
12.75
12.75
0.00
13.06
13.06
0.00
NB56
11.12
11.12
0.00
11.77
11.77
0.00
NB57
9.53
9.53
0.00
11.58
11.58
0.00
NB58
6.00
-. -6.00-----------0.00.....---
--- 7.89 ----
---- 7-89-
-
--- 0.00-----
NB59
13.51
13.51
0.00
13.79
13.79
0.00
NB60
6.65
6.65
0.00
9.66
9.66
0.00
NB61
5.64
5.64
0.00
7.32
7.32 I
0.00
NB62
5.40
5.40
0.00
7.94
7.94
0.00
NB63
10.34
10.34
0.00
11.21
11.21
0.00
NB64
11.22
11.22
0.00
11.71
11.71
0.00
NB65
5.64
5.64
0.00
7.64
7.64
0.00
N B 66
10.13
10.13
0.00
10.87
10.87
0.00
NB67
3.87
3.87
0.00
6.90
6.90
0.00
NB68
10.35
10.35
0.00
11.21
11.21
0.00
NB69
9.65
9.65
0.00
10.87
10.87
0.00
NB70
11.21
11.21
0.00
11.87
11.87
0.00
NB71
13.90
13.90
0.00
16.10
16.10
0.00
NB72
9.62
• 9.62
0.00
10.87
10.87
0.00
8-7
February 2012
City of Miami
Phase II-.Stormwater'Management Master Plan Final
It �
' Sib basin
:F;
Bese1ih
F.ra+. �'
p St:enano
y`ear
'Constructor
- ... s.Hn,
Scenanoi
' ' 5 year .,.
" t' DJfferencea
b .. -�, x.c .wt"
BJW 5ykearm
'' Scenarios ,..
„,1Baselinei
V ,k�f
Scenario
� 1
,.':.�UO1.yearx.,.
' sConstruCtion
�+ .'.r- h
"Scenario
,. y �'
*�100rear v�:4
� Differences; i
r �-s .1
s BIW-.7D0,year
'Scerianos,d
' NB7.3 '
' '=-6:07
'6:07
- 0:00. •
8.57 -
..- 8.57,.-
' MO.
NB74 ..............9:60
9:60"
0:00' ...,-
... 10.88'.....
_....-_:10:88'.........
......0:00`._ .. .- -
NB75
9.60
9.60
0.00
10.88
10:88
0.00
NB76
10:26
10.26
0.00
10.87
10.87
0.00
NB77
9:60
'9.60
0.00
10:88
10.88
0.00
NB78
4.52
4.53
0.01
6.15
6:15
0.00
NB79
4.88
4.88
0.00
6.40
6.40
0.00
NB80
9:60
9:60
'0:00
10:88
10.88
0:00
NB81
3.82
3.82
0.00
4.73
4.73
0.00
NB82
5.60
5:60
0.00
6.02
6.02
0:00
NB83
4.91
4.91
0.00
7.01 •
7.02
0.00
NB84
8.34
8.34
0.00
8.96
8.96
0.00
NB85
6.60
6.60
0.00
8.86
8.86
0.00
NB86
4.57
• 4.57
0.00
4.57
4.57
0.00
.-NB87 .K
? ; 4?42 ..,
:: 3 08 , . ar'
P1135ki.4
?.r,15492 . r.:,:
..,'M, w4.94 t°`_ ;
i _D:98 r ..> ++
NB88
4.03
4.03
0.00
•5:69
5.69
0.00
: NB89 _ 0
c ..4:42$..."
.;:e3 08 '...'A
a a. °1:35 r n
. aA;'5 92 ,..:;
. w 4.49k :.., ,;
_.c 7,.• ' `.. :.-
NB90
2.88
2.89
0.00
3.97
3.97
0.00
NB91
4.03 I
4.03
0.00
5.69
5.69
0.00
NB92
4.34
-4.34
0.00
5.11
' 5.11
0.00
NB93
2.75
2.75
0.00
•3.80
3.80
0.00
NB94
2.76
2.76
0.00
4.05
4.05
0.00
NB95
4.05
4.05
0.00
5.05
5.05
0.00
S B 01
11.74
11.74
0.00
12.08
12.08
0.00
,SB02 ..:`?.
-:.3 87.
r .3 86 =:' N.
..: 0.01::;;:a
r . -s'5 91 r c
'.05 91 a ::,:
;0:DO
SB03
15.41
15.41
0.00
15.80
15.80
0.00
SB04
9.72
9.62
-0.09
11.30
11.29
-0.01
SB05
6.44
6.44
0.00
10.58
10.58
0.00
' ='SBO6 �:'�'$.
.:.9�2
,.:+ ..a9.62.:;�� n
c.�:,::..0.091.;.
11.30. �.._..�.,
�11:29 ..- *.:
'_.., 0.01- ..:;;
SB07
6.29
6.27
-0.02
8.46
8.45
-0.01
SB08
7.96
7.93
-0.03
11.25
11.23
-0.01
SB09
9.39
9.37
-0.01
11.30
11.29
-0.01
_::'SB10 .-
9 39,_ °
s _.. . 9 38.: i
0 02`c.::.
".1;1 30',17,44
fail:.1°1.29 ?,•
_.., ::.0':01 ,:
SB11
9.89
9.89
0.00
11.24
11.23
-0.01
SB12
8.74
8.72
-0.02
11.25
11.23
-0.01
SB13
9.39
9.38
-0.02
11.30
11.29
-0.01
SB14
8.74
8.72
-0.02
11.25
11.23
-0.01
SB15
8.27
8.26
-0.02
11.24
11.23
-0.01
S916
11.04
11.03
-0.01
11.64
11.64
0.00
--SB17_ ;.
11::12. at
I,F. _11 11, '-
0"02.`."`
x'., .11 67. :
:'.r''9.1 67,mi '
' k t0.00 i4g:,,,
SB18
4.54
4.53
0.00
5.72
5.72
0.00
10.56
-10 56---
- -0:00 -
-11.25
'11724
0.01
•
SB19
S B20
10.58
10.58
0.00
11.38
11.37
0.00
S B21
11.04
11.03
-0.01
11.64
11.64
0.00
S B22
11.58
11.56
-0.01
12.12
12.12
0.00
SB23
9.77
9.77
0.00
11.38
11.37
0.00
SB24
10.65
10.65
0.00
11.28
11.28
0.00
SB25
9.77
9.77
0.00
11.38
11.37
0.00
SB26
10.65
10.65
. 0.00
11.28
11.28
0.00
SB27
10.58
10.58
0.00
11.38
11.37
0.00
SB28
9.79
9.79
0.00
11.38
11.37
0.00
SB29
10.58
10.58
0.00
11.38
11.37
0.00
S B 30
11.78
11.78
0.00
13.17
13.17
0.00
SB31
9.76
9.76
0.00
11.38
11.37
0.00
SB32
7.86
7.86
0.00
10.98
10.98
0.00
SB33
10.65
10.65
0.00
11.28
11.28 •
0.00
SB34
9.54
6.55
-3.00
11.38
11.37
0.00
SB35
9.54
9.55
0.00
11.38
11.37
0.00
SB36
11.15
11.15
0.00
11.28
11.28
0.00
S B 37
14.60
14.60
0.00
16.07
16.07
0.00
SB38
3.10
3.10
0.00
4.77
4.77
0.00
SB39
4.55
4.55
0.00
6.07
6.07
0.00
8-8
February 2012 City of:Miami
Phase II - Stormwater Management Master Plan Final
The following attachments provide result data from the Completed and -Under
Construction model scenario for both the North and South Biscayne Basins:
• 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.
8.5 Projects Under Design
As described previously, due to the duration of the two phases of the SWMMP update
process, all of the projects which we initially in the design scenario for Phase II, have
transitioned into the constructed scenario. This includes project B-30011. The
components of this project were evaluated and included into the Construction Scenario
XP-SWMM models.
8.6 Sub -basin Rankings& Comparisons
The sub -basin rankings were performed using the same ranking procedure as applied
to Baseline Scenario with no deviations. The same approach for quantifying the various
parameters were also used for the Construction Scenario rankings. These procedures
and approach were carried over from Phase I for the..purposes_of maintaining continuity
and congruence between Phase I and II and between the various scenarios.
Table 8-9 provides a summary of the rankings obtained for the Baseline Scenario and
the revised rankings from the Construction Scenario Sub-basir►s highlighted rn yellow
are sub -basins where model parameters were adjusted to account for stormwater
management projects which fell under the Construction Scenario. Additionally a
'comparison was performed showing the difference between the Baseline and
Construction scenario.
The ranking results did not show any significant changes in rank with the exception of
two sub -basins - SB87 and SB89. This minor change in overall rankings 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.
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).
8-9
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
Table 8-9 — Sub -basins Rankings arid Comparisons • •
Sub ba in "
N'AVM
A:Baselin•"
Rank
} Constructi•bnESeenatior ,
G an1,
fB mparison#to
SB09
1
1
0
:'SB06,` - t:.
r, 2 ,..r...
a . r,:,.4,, + giiiga..M
tn.. Oc ',.
SB25
3
3
0
SB23
4
4
0
,;, i
S; fi. 1•..SB;I �.
,� . ,-
� :f, w5. n�
w tom;
v +i Wit'. _,...5 tx,?i}alg:.
...A .r 0_.,.:2: :-.13
SB04
6
6
0
SB30
7
7
0
SB13
8
8
0 t
SB14
9
9
0
SB34
10
10
0
SB33
11
11
0
SB28
12
12
0 •
SB20
13
13
0
SB18
14
14
0
SB12
, 15
15
0
NB77
16
16
0
=x.AN B891 :;
,_. Zj 17'^. _R
.:. ,34 K4 - _.
, :- w. 170...1
NB64
18
17
1
SB31
19
18
1
NB66
20 •
19
1
NB69
21
20
1
SB26
22
21
1
• ,SB02 a°s,..,
.... .23,.rt. C
i.. ::::..22-_. 4..
- 1..::.."
NB58
24
23
1
NB75
25
24
1
SB19
26
25
1
• SB11
28
27
1
NB61'.
"29
• 28
1
SB38 •
30
29
1
NB87 i" `,
: r-31_1`.:i
i....'t40 ....... _ `
_ .:."x = ... 9.::;_„
NB80
32
30
2
NB65
33
31
2
NB72
34
32
2
SB07
35 :
33
2
NB95
36
36
D
NB71
37
35 •
2
SB16
38
37
1
NB73._..__--
____. 39 _
-38.... . _
1
NB83
40
39
1
SB24
41
41
0
NB64
42
42
0
SB05
43
43
0
NB49
44
44
0
NB94
45
45
0
SB15
46
46
0
NB56
47
47
0
• SB35
47
47
0
NB81
49
49
0
SB39
50
50
0
SB01
51
51
0
NB41
52
52
0
NB92
53
53
0
SB21
54
54
0
NB63
55
55
0
SB03
56.
56
0
SB32
57
57
0
NB46
58
58
0
NB76
59
59
0
NB44
60
60
0
8-10
February.2012 City of: Miami
Phase' II - Stormwater Management Master Plan Final
`Su basin
raN
4? ,,,
"' �"eviv
BaseItne
,
1-,-
.r
ConstructiontScenarlo Pil
..'
+Rank
,".
}r,..
t
..:
t ECom..n:n,4 M
..:Baseline4Ranwk
• NB74
61
61'
"
NB57
.62
62 ..
0...__....:....
•NB90
63
.63
0
SB36
64
64
0
NB79
65
65
0
SB08
66
66
0
SB37
67
67
0
NB59
68
68
0
NB68
69
69
0
'" _` NB43
.4##1143F7AM
,- :�
70*:.`_
;13
5"n"' `-_
NB85
71
71
0
NB88
72
72
0
NB93
73
73
0 '
NB91
74
74
0
NB45
75
75
0
SB27
76
77
-1
NB60
77
76
1
NB50
78
78
0
NB78
79
79
0
NB67
80
80
0
NB84
81
81
0
NB53
82
82
0
NB86
83
83
0
NB70
84
84
0
._.NB4.7 __
_..-"
,n?z'185 _s
..m..::.,
.{85 �...':
_
.... oil ti ?r.
. .
SB29
85
85
0
NB40
87
87
0
''.' 4nNBilgig
gi*iff88 '..::
88
/oot0000
/
ƒ
SB22
89
89
NB55
90
90
NB51
91
91
NB52
92
92
NB42
93
93
NB62
94
94
NB82
94
94
8.7 Repetitive Loss Properties
Of the 71 repetitive loss properties within the repetitive Toss database, none of the
properties may potentially be removed from the database because the estimated
building finished.flobr elevatibn-are all below the 100-year flood plain elevation - see
Table 8-10. 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 68 of the 71 properties listed in Table 8-10 were built before 1980 and the
building finished floor elevations may actually be below the estimated values.
Attachment U provides maps showing the repetitive Toss properties within the limits of
this Phase II SWMMP in relation to the FEMA Flood Hazard Zones AH and AE and the
flood plains defined through this SWMMP.
8-11
February 2012
City. of.Miami
Phase II Stormwater Management'Master Plan.Final
Table 8-10 - Sub_basins with Maximum:Number of Repetitive Loss Properties
S
'4'
o a `
i Sl-ly.,
F basfi
x' 'Fioo `
c ��
.;yEl'evat(on
OP r tum if)k (City
s 1 �-
Depth of, 1. '
Floodin
FOLIO +
' ,,Built
1sVBaselme�;`,,?
sE.Cvnstructiont
*� � {ft) s 1
• :0141160161571
1953
SB06
2.18
- 11.30- " •
1129 "
9.11
0141160161660
1949
SB06
2.24
11:30
11.29
• .9:05
01.41160160710
1961
•SB06
2.34
11:30
11.29
8.95
0141160152630
1977
SB06
2.59
11`.30
11.29
8.70
014.1160152610
.1961
'SB06
2.68
11.30
11.29
" '8.61
0141210131170
1919
SB04
2.74
11.30
11.29
8.55
0141160160920
1960
SB09
2.80
11.30
11.29
8.49
0141030140480
1971
SB31
3.15
11.38
11.37
8.22
0131330133040
1949
SB10
3.40
11.30
11.29
7.89
0131340460080
1944 •
SB25
3:74
11.38
11.37
7.63
0132300150050
1956
SB33
3.67
11.28
11.28
7.61
0132190140011
1938
NB64
4:13
11.71
11.71
7.58
0131270270780 '
1970
SB11
3.76
11.24
11.23
7.47
0131330040090
1947
SB13
3.82
11.30
11.29
7.47
0141100632250
1926
SB25
3.96
11.38
11.37
7.41
0131330145000
'.1950
SB13
3.93
11.30
11.29
7.36
0131330130082
1959
SB13
3.94
11.30
11.29
7.35
0131330142110
1950
SB10
3.95
11.30
11.29
7.34
0131330130050
1954
SB13
4.01
11.30
11.29
7:28
0131330130060
1950
SB13
4.02
11.30
1 11.29
7.27
D131330220440
1951
SB17
4.42
11.67
11.67
7.25
0131330040310
1947
SB13
4.09
11.30
11.29
7.20
0131330020030
1968
SB13
4.09
11.30
11.29
7.20
0131330040060
1947
SB13
4.09
11.30
11.29
7.20
0131330020020
1965
SB13
4.11
11.30
11.29
7.18
0131330040440
1947
SB13
4.13
11.30
11.29
7.16
0131330132740
1955
SB13
4.13
11.30
11.29
7.16
0131330310130
1978
SB13
4.15
11.30
11.29
7.14
'0141020056350
1952""'
SB34
4:28` •
11.38'
_11.37
7:09..
0131350160660
1923
SB25
4.49
11.38
11.37
6.88
0132300230330
1973
NB49
5.29
12.01
12.01
6.72
0141220110001
0
SB07
1.90
8.46
8.45
6.55
0141210680100
1970
SB05
4.18
10.58
10.58
6.40
0141210680180 .
1970
SB05
4.18
10.58
10.58
6.40
0141220130001
0
SB07
2.09
8.46
8.45
6.36
0141380015172
1960
SB32
4.79
10.98
10.98
6.19
0141220011500
1982
SB07
2.26
8.46
8.45
6.19
0141390340001
0
SB36
5.38
11.28
11.28
5.90
11.28 .___
... 1-1.28
86
-0141.14006077.0._...._
0141140050010
_.1.969 __
0
_..._SB24 .
SB24
_5:42
5.67
11.28
11.28
5.61
0132300260181
1919
NB58
2.48
7.89
7.89
5.41
0132300260120
1922
• NB58
2.73
7.89
7.89
5.16
0141150230240
1953
SB18
1.06
5.72
5.72
4.66
0141280140120
1937
SB02
1.74
5.91
5.91
4.17
0141280140180
1923
SB02
1.75
5.91
5.91
4.16
0141140010101
1976
SB18
1.65
5.72
5.72
4.07
0132310070020
1956
NB54
2.05
5.93
5.93
3.88
0141140010090
1924
SB18
1.85
5.72
5.72
3.87
0141280140090
1931
SB02
2.07
5.91
5.91
3.84
0141220011600
1925
SB18
1.88
5.72
5.72
3.84
0141150210231
1989
SB18
1.97
5.72
5.72
3.75
0141150210140
1958
SB18
2.06
5.72
5.72
3.66 •
0141150250170
1955
SB18
2.30
5.72
5.72
3.42
0141150540260
1981
SB18
2.31
5.72
5.72
3.41
0132070320670
1956
NB87
1.56
5.92
4.94
3.38
0102100501010
0
SB36
1.54
4.77
4.77
3.23
0102100507010
.1973
SB38
1.58
4.77
4.77
3.19
0132070320990
1951
NB87
1.78
5.92
4.94
3.16
0132080210090
1959
NB95
1.95
5.05
5.05
3.10
0132070030170
1941
NB92
2,29
5.11
5.11
2.82
8-12
February.2012
City of Miami
Phase II - Stormwater.Management Master Plan Final
�-;.�,
OL10 � �
gi ' , s z n
lv ..... , r. , r,
�
ear'
Built
,�1 <
� �, µ.v �,�'7F!mhedi+��
, sub
,r4
basin
t _.,l n w
3� Floor
� 100 Year�PeatC Sta_gest{Cityl ',
N "' ' a
�� i`: m3Datum ft
•Depth of'�} s
loodln
Fir F o g'
ft )� _
- { $
2:77.
N.
,. , ,
Ievation '
��
Baseline
1` Cons uction , 1
tr -
`0132080210f30'
1961'`'
. NB95'
' 2128 '
'5:05-'
"'5 05 ` -
.-'01321.80280360..,....._...,,1939
_......,-NBB.1`•._..
..._... 1:98,.........._.....74}73....,
..._...,.,_....._._..-4-.73
_.........__.
_-...._.,.-2:75.__-,..,........
0132070380210
1949
NB89
1:74
5.92
4:49
2.75
0102090901030
1971
S638
2.03
4:77
-4.77
2.74
0141390440001
0
SB38
.2.15
4.77
4:77
2.62
0132300460001
• 0
NB57
9.42
11.58
11:58
2.16
0132D70040031
1950
NB94
.1.98
4:05
4.05
2.07
0132070310880
1949
NB89
2.50
5.92
4:49
1.99
0132190380010
1950
NB79
4.73
6.40
6.40
1.67
0132080260060
1977
NB94
2:44-
4.05
.4.05
1.61
0141390410001
0
SB38
4.58
4.77
4.77
0.19
Of the 71 repetitive loss properties which are within the limits of Phase II of the SWMMP
update, 15 of those properties are within sub -basins where flood protection projects
have been recently constructed. Table 8-11 lists these sub -basins and quantifies the
number of repetitive loss properties which are within the 100-year flood plain of that
sub -basin.
Table 8-11 — Sub -basins with Maximum Number of Repetitive Loss Properties
'
,ESLbabas!n n'rPropertieswithim
� G
Number o Repet�trve Loss
ubbasm;..k.
INumbersot Proper IOI*h�chaare;.wrthrn 4
the l2 orrmore{100year floodlaplam fo
,.,,>ttie,Construction;S'cenarios"
SB02
3
3
SB06
5
5
SB10
2
2
SB17
1
1
NB87
2
2
NB89
2
0
8.8 Construction Model Scenario Conclusion
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 from the total project area or 2.5" of runoff
from the total impervious project area). Also, pump station parameters and operating
conditions were collected from the plans provided by the City, and the pump capacities
and operating conditions were then directly incorporated into the models.
The model results obtained from the Construction Scenario showed minimal reductions
in flood stages for the 5-year event and 100-year design storm events with the
exception of sub -basins NB87 and NB89, where reductions were at or exceeded 1.0-ft.
An Under Design Scenario was not developed due to the projects initially slated to be
included in this scenario transitioning to the Construction Scenario.
The ranking results did not show a significant change in rank. The minor changes in
ranking were attributed to the fact that most of the stormwater management systems
incorporated into the models are secondary drainage systems meant to remedy
8-13
February.2012 City of Miami
Phase II - Stormwater Management Master Plan Final
localized .flooding. 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 structuresfloodedwhich is::the highestranking 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, with the exception of
those areas which are shown to be in FEMA Zone X. There is some expansion of the
flood plain which can be attributed to the higher resolution topographic data which was
used for this SWMMP.
Additionally, the analysis of the repetitive Toss properties suggests that the removal of
the properties from the repetitive loss database may not be possible 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
noted that of the 71 repetitive loss properties within the repetitive Toss database, that
none were estimated to be above the 100-year flood plain.
The results obtained from the Construction Scenario model suggests that improvements
in peak stages can be accomplished with projects such as the Belle Meade pump
station project (B-50672). In order to achieve larger reductions in peak stages
throughout the City, systems with the capability of significantly improving the discharge
capability of a system from a sub -basin would be required and would be dependent on
the sub -basin size, location, extent of existing infrastructure, and available CIP budget.
8-14
February 2012
Cify„Pf IV iami
Phase.I1 Stormwater.Management`, Master; Plan:,Final
ROVEMI
-
-
-Proposed storiiiwater--management..systems-must adhere to..stnct water. quality and.-
quantity criteria set forth by' various local, state, and :federal agences.:with 'jurisdiction
within'the state of Florida. All new -or improved stormwater managernent`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 Taws.
The typical stormwater management systems used within the City of Miami include
positive drainage systems, exfiltration trenches, injection wells, and stormwater pump
stations. These systems, as well as their performance within the parameters of the
analyses performed for this SWMMP are detailed further in the following sub -sections.
9.1 Water Quality Regulatory and 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 now PERA), 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.
9.1.1 Miami -Dade County DERM (now PERA)
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 18.1-1 through 18.1-4.
V = 60CiATt Equation 8.8-1
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 18.1-2 -
i = Rainfall intensity, inches per hour, from Equation 18.1-4
9-1
February.2012 City of Miami
Phase II - Stormwater Management Master Plan Final
Tt _ Ti„ + Tc
Equation 8:8-2
Where , , :Tc _ - Time: of concentration, minutes
Tv. = Time.to.generate one inch of runoff, minutes, from Equation 18.1-3
T1„ =
2940 F-0.1 Equation 8.8-3
308.5 C 60.5(0.5895 + F-o.67)
Where F = Storm frequency, years
i =
308.5 Equation 8.8-4
48.6F-o.1 + Tt(0.5895 + F-o.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 less than.24 hours
and the use of bleeder mechanisms is not allowed.
9.1.2 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-oatlined-render-item #3--appiies=to
all systems within the City of Miami.
9-2
February 2012 City of Miami
Phase II - Stormwater. Management Master Plan'Final
9.1.3 Florida Deoartmentof 4miironment4Protec€ion
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 standardsset 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.
9.2 Water Quantity Regulatory and Permitting Requirements
The following subsections outline the most stringent stormwater quantity requirements
applicable to any City of Miami projects. 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.
9.2.1 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:
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 over the 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.
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.
b)—A-flood-routing-method-is-used-using a-25-year-24-hour-storm-(S-FWMD 2-4 hour
distribution) no infiltration. The system is allowed to pond up to the finished floor
9-3
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
elevation.
• For systems affecting finished floor elevations
a)....:2:5-year,:_3-day.forsystems with outfal.ls
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.
9.2:2 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. However, there are no Miami -Dade
County canals within the Phase II limits of the City.
9.2.3 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)
Figure 1-1 shows the limits of each basin, and Table 9-1 includes the allowable
discharge criteria as per SFWMD requirements. For the Phase II limits, this
requirement is not applicable because there are no canals within these portions of the
City. 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
(i.e. C-4, C-6, and C-7), SFWMD requires that the post -development peak discharge
9-4
February 2012 City of Miami
Phase II - Stormwater Management Master PIan:Final
rate from these:projects,be maintained at or_below the -pre -development peak discharge
rate fora 25'year, 3-day.design storm. event: The North and South .Biscayne`;Basin are
basins whicf discharge to tidal waters and.thus essentially, have,unlimlted,d:scharge,
Table 9-1 — SFVVMD Allowable Discharge.Rate Formulas for Basins with Restricted Discharge
; y. % ��
C anal: l
r`d ,q}n y „tkr n , F 3:,� [?y
n
� r `k AI ow ble Discharge ate Formuuta =r tiryY4
TS•,, esti-
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 unlimitedinflow by gravity. connection
100 year +
Where A = drainage area in square miles
Q = allowable runoff in cfs
CSM = cfs per square mile
9.2.4 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:
• 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.
• 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.
The peak discharge rates and total volumes allowed by applicable local
regulations arenotexceeded.
• The improvements shall not increase stormwater discharge rates above the pre -
development conditions.
• The quality of water conveyed by the connection meets all applicable water
quality standards.
9.2.5 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 infection well depth and horizontal
location must be adequately defined where the total dissolved solids exceed this limit.
9-5
February.2012 City of Miami
Phase II - Stormwater Management Master Plan.Final
requires that the stage 'at an injection well
may{ otaexceed . ah elevation District greater thanD80:ft-Nwhen
...cite. ....
ft=NGVD . .associatedwvitl a .pump
•station. This restriction is to, prevent vertical migration of injected water along:the well
casing. For gravity injection wells, the elevation will .be controlled by the natural ground
topography.
9.2.6 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.
For the Phase II sub -basins, the Average October groundwater elevation primarily
ranges between 2 to 3 ft-NGVD, with elevations increasing from east to west.
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 based on the criteria described in
Section 9.2.1.
The SFWMD and Miami -Dade County DERM also require flood protection of habitable
buildings. The peak elevations for a 100-year, 3-day design storm event 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.
9.3 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 measures were each evaluated for
___..__.implementation into__the,.,sub-basins based on the existin_g_stormwater management and
drainage 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 is described in this subsection and the effectiveness
of their implementation within a sub -basin will be further evaluated in Section 9.0.
9.3.1 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 wereconstructed
prior to the advent of modern stormwater discharge regulation. These systems can
9-6
February 2012 City. of Miami
Phase II - Stormwater Management Master Plan:Final
remain •in place :in the event that no additional impervious area or. increase -'in post-
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•systern are increased, these systems.are then required -lb -meet all of the
applicable, quantity and quality criteria previously described in Sections .9:1 and 9.2.
'These criteria are often met by converting these discharge only systems into systems
which infiltrate and/or injection stormwater runoff into the groundwatertable.
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.
No positive drainage systems with outfalls were proposed for Phase II although these
systems would be allowable with adequate water quality measures implemented.
9.3.2 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 for 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 .9-1 shows a ypical_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 (ft) 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.
9-7
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
PROPOSED RDADvAT
... " � SURF ACCELEVATION —1\
I Iiris
ji
TAKE
PERFORATED I
Irc
9'
HOFr'crr UP.AiL1
PIPE
i
BAFFLE •--J�
•\\ rtLTEP FABRIC
— ENVELOPE
\ AGGREGATE
'—MEDIA
B• _ .SLTTEh .�
140t4._OTTEL 1 Pipc
PIPE
FILTER FABP.IC j
ENVELOPE —
PROFILE
AGGREGATE
M,J
MEDIA
3' NAIt
WIDTH
VATER `•'`J
TABLE
FILTER FABRIC /
ENVELOPE
AGGREGATE
MEDIA 1
4' NMI:
44 'IN
CROSS
SECTI❑N
22' MA):
DEPTH
Figure 9-1 — 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 6-1.
Calculation Example 9-2 — Exfiltration Trench Extraction Volume Calculation Example
-WGivenExflltratwn.
t T1'00lengfh nd _ �
ConfnbutingSArea`. 1
Exfiltration trench length for project = 4,000 If
Contributing width = 320 ft
Total drainage area = (4,00D If x 320 If) / 43,560 = 29.38 acres
VEMractionxYolame`f4r ,t
aExf l rattom rent 41
Extraction depth per unit area = 3.28"
Prorated extraction depth = (3.28" x 29.38 acres) / acres = 96.38 acre -in = 8.03 acre-ft
�I I 'r, n r
ub4rmul,k anFlv�OpYear
tt--e-X0 Vatu -- l,I x
Sub -basin - CC7-S-24
100-year Peak Stage = 10.81 ft-NGVD
100-year Peak Volume = 165.12 ac-ft
RevlsedlDDYear Peat
Revised 100-year Peak Volume = (165.12 - 8.03) = 157.09 ac-ft
The representation of these types of improvements is shown in Attachment W as lines
where these improvements may be implemented. The project prefix is presented as
PR.
9-8
February:2012
City: of Miami
Phase II - Stormwater Management Master. Plan Final
9 3 3 D y tention-Basins
Retention. basins are dedicated areas with topographic elevations which are lower than
:the..surro,unding,areas and are often interconnected with :stormwater collection systems
throughout'the surrounding areas. These .basins typically' have a bottom elevation
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 stormwaterrunoff 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 9-3.
Calculation Example 9-3 — Retention Basin Volume Calculation Example
,s
Retention Basin
Locati n Daa' t'
S � k rS�1f
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)
.
�,._.�.� fl
Lowest adjacent grade elevation="8:5'f1=NGVD
iRetentioniBaSm 'ar
Voiu�setric`Cai, ity 3w(
AvaVolume ilable = 10 acres x 8.5' - 3.0' 55 acre-ft
)
Sli�b� asing1,Ti A�'Ysaf
PeakaaIues al.OP h'p
} $
.r`K'r'.'t�L•=u'!6LE��i.2i;4''1�:?
Sub -basin - CC7-S-21
100-year Peak Stage = 11.21 f1-NGVD
100-year Peak Volume = 166.11 ac-ft
Revisedt10% eraneak
44.04.14r ua H `
Revised 100-year Peak Volume = (166.11 - 55 ) = 111.11 ac-ft
No retention basins were proposed for Phase II due to the almost built out nature of the
Phase II limits.
9.3.4 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
dissolvedsolids_(TDS)_requiremen.ts.—Injection_drainage_we.is_are_typ.IcaIly- used--o.nly
9-9
February.2012 City of Miami
Phase II - Stormwater Management Master Plan -Final
when., it ,is, not practical to use exfiltration trenches because of low spil hydraulic
conductivity. Figure 9-2 shows atypical section of.an injectiory.drainagemell.
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
INELAV PIPE
AVERAGE YEARLY LAN
WATER ELEVATION
WELL .CASING
24' PIPE
END OF PIPE
UNCASED•WEELL
BOTTOM. OF. WELL
Figure 9-2 — 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 fora _givenLvolume __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
9-10
February 2012 City of Miami
Phase II - Stormwater Management'MasterPlari Final
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: -
An example. of 'the volumetric capacity;..of an injection well system based: on these
considerations is -Shown • in Calculation.Example 9-4.
Calculation Example 9-47 Injection Well Volume Calculation Example
iueRInfection4Well
ub bath andi-100Year
eakWalbestit.,' _
Injection well capacity = 500 gpm per foot of head
Groundd✓ater elevation =.2 ft-NGVD
Mounding effect= .1.5 ftof additional head required
'Total number of injection wells .= 30
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 30 wells = 111.96 acre-ft
Sub -basin - CC64N=12
100-year Peak Stage = 6.80 ft-NGVD
100-year Peak Volume = 171.28 ac-ft
Re isedc 10A.YYea.r
VOIUIflej. �'tam"x���a?:
Revised 100-year peak volume = (171.28 - 111.86) = 59.38 ac-ft
The representation of these types of improvements is shown in Attachment W 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.
9.3.5 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 9-3 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.
9-11
February.2012
City of Miami
Phase II - Stormwater Management Master Plan Final
WET WELL
BAR -
GRATE
STORMWATER
VALVE
FITTINGS BOX
PU JIPS 7
RUNOFF
•
FLOW
Figure 9-3— Typical Stormwater Pump Station Plan
The representation of these types of improvements is shown in Attachment W as
polygons where these improvements may be implemented. The project prefix is
presented as PS.
9.4 Volumetric Analysis
The effectiveness of the proposed stormwater management system improvements
described in Sections 10.1 through 10.15 were evaluated based on the stormwater
management system's capacity to remove excess 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 definedwithin the XP-SWMM...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
as detailed in the previous section. 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 flood stage. This improvement goal was described as eliminating flood
conditions for.25% to 50% of the properties within the sub -basin for the 100-year, 7.2-
hour event. The removal of flooded properties from the floodplain was used due to its
controlling factor in the scoring and ranking procedures 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. This detailed
analysis should be performed as part of the detailed design of the project.
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, such as reduced flood duration, improved flood protection during small
frequency rainfall events, better quality. of stormwater discharges to receiving water
bodies, and reductions in total flows to adjacent sub -basins.
9-12
February:2012 City ofMiami
Phase II - Stormwater Management-Maste:Plan Final
5;5 Future Improvement Project Formulation Conclusion
Each sub basin Was Successfully_ evaluated in -terms of toppglaphy, location relative to
receiving water bodies, existing infrastructure, and feasibility of implementation of
stormwater management systems.
Projects were forrnylated and .the projects were evaluated based on reducing the depth
of flooding and identified -the total excess volume. 'to be -mitigated by these projects.
StorniWater management systems which included exfiltration trenches, pump stations,
and injection wells, were analyzed for their effectiveness at reducing the flood 'stages
duringsthe.greater intensity, storm events. Peak stages from the model runs were then
correlated to a peak volume for each of the trip 15 Sub -basins and an extraction based
on these'proposed systems was performed. •The reduced volume was -then interpolated
to a given lower stage. The resulting lower stages were then correlated to a reduction
in flooded structures and roadways thus resulting in 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.
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 for the 100-year, 72-
hour event.
Each projedt 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. Cost for
these proposed systems were also evaluated and 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. These driving factors resulted in
the majority of the construction cost for these projects being around $2,000,000.
9-13
February2012
• ,C ity;of_ Miam i
Phasell,,;Stormwater-Managemerif:.Maste Plan:"Final
The following sub -sections describe and •evaluate the top 15 sub basrns based• on the
analysis and ranking procedures for this SWMMP update - see Table 10 1 for_top :15
sub- basins. All'1'5 of the top ranked sub -basins fell .within the South=:Biscayne Basin.
Each sub -basin was evaluated in terms of: topography, location .relative to receiving
ising • df._a....i..,_..y p .......
water bodies,.existm infrastructure, and feasibilit :of im lemeritation of stormwater
management systems. Proposed stormwater management systems were evaluated
using the extraction methodologies described in Section 9.0.
Table 101 —Top 15 Ranked Sub -Basins
1 ;� ��,.
Scenasa
�,,�
.
sub -basin �Y
, d� .w
,;x�.f
.RanK,:-
1
SB09
2
SB06
3
SB25
4
SB23
5
SB10
6
SB04
7
SB30.
8
SB13
9
SB14
10
SB34
11
•
SB33
12
SB28
13
' SB20
14
SB.18
15
SB12
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 __b.riefly__described_ b.ase.d_ on_Jhe •
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 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 also 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. Cost for these
proposed systems evaluated in Section 11.0.
For the majority of the top 15 ranked sub -basins, the topographic makeup of each sub -
basin and _the . location .of .the .sub -basin relative .to .the saltwater -intrusion .zone allows -for
10-1
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
the effective use of injection wells under gravity. For these reasons, injection wells
under gravity will be used extensively within the Phase II proposed projects.
10.1 Rank #1 - Sub -Basin SB09
The topography for sub -basin SB09 has a depressed region which runs from the
southwest portion of the sub -basin northeasterly towards the center of the sub -basin
see Figure 10-1. This sub -basin's topographic elevations are average when compared
to most areas within the City.
LEGEND
QBasin Boundary
Stormwater System
Figure 10-1 — Sub -basin SB09 topographic trends & existing stormwater infrastructure
The southern limit of this sub -basin is at South Dixie Highway (US-1), while the northern
limit is at SW 22nd Street. Bound approximately on the west by SW 32nd Avenue and
SW 27th Avenue on the east.
The main stormwater infrastructure components for this sub -basin consist of isolated
self-contained drainage systems with exfiltration trenches. The slightly higher
concentration of isolated systems are on the south side of the sub -basin, south of SW
27th Street.
10-2
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
The peak stage and volume based on the model results for the 100-year, 72-hour for
this sub -basin are presented in Table 10-2. Additionally, the 25% and 50% goals for
this sub -basin are also shown in this table.
Table 10-2 — Sub -basin SB09 Stage Reduction Estimates
; Ifkjaagninggial _ Exlsting`Gonditidfi
k, ' : ,f `x - "
100-year peak flood stage
11.30 ft-NGVD
100-year peak flood volume
444.44 ac-ft
Number of flooded structures during 100-year design storm event
841
K
s `•ca 4g, r . i . :,*25%.`FlootledfstructureFRetl..uctionl;,;,
>,;;
" ufi•*.i;s. _.
Peak stage to reduce number of flooded structures by 25%
10.57 ft-NGVD
Peak volume to reduce number of flooded structures by 25%
291.22 ac-ft
Total stage reduction
-0.73 ft
Total volume to be extracted
-153.22 ac-ft
Total reduction in the number of flooded structures at 25%
-210
:_ Ed , w _ f 4 U% Floodgitt ructurelReducVon
, ,
.il ,:• Mtn
Stage to Reduce number of flooded structures by 50%
10.00 ft-NGVD
Peak volume to reduce number of flooded structures by 50%
189.65 ac-ft
Total stage reduction
-1.30 ft
Total volume to be extracted
-254.79 ac-ft
Total reduction in the number of flooded structures at 25%
-421
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.
In this sub -basin, significant quantities of exfiltration trenches can be provided to reduce
flood conditions towards the 25% reduction goal. In addition to the exfiltration trenches,
interconnection to gravity injection wells may be used to provide additional reduction in
overall. This sub -basin sits inside the saltwater intrusion zone, therefore, injection wells
are a viable option for expediting flows into the groundwater table.
The proposed improvements for this sub -basin as well as the removal capacity of the
proposed systems are shown in Table 10-3 and general locations for these
improvements are shown schematically in Attachment W-1.
Table 10-3 — Sub -basin SB09 Proposed Stormwater Management System Components
%�k�� ^�C? 'fit. '4A F :'T
ih xc^ -s �,y
x_r4 item? k,� . r &n''46
J'-0j ry3!. 12{C. �, 2� y
2 ;e ntity -
uanti ,,,
�. Itractionlvolume' '
{7a: (ac �t per i�'�
ru.t�iei a°...ft Pett' .
'r+�'`," fr p. �. `3 .ri:-e....:',. -'.' a i mr' tpl1�1 'p'" . +I# ,.'i
r K �w.t'k�.��.,"".. 3 p 'S. L'v st. 4 r�'�, N-
» _�_.. _ ,_._..: Des —di flanl Commerits . ...tY.���_::t!
Exfiltration Trench
21,000-ft
42.17 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
Will convey runoff to the groundwater.
1., <<;;Total;5gstem Capacity ..<.,,: 1'_ .:.'1'541`03rac=ft n -.:'
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 -0.73 ft.
10-3
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
10.2 Rank #2 - Sub -Basin SB06
The topography for sub -basin SB06 is generally higher than other areas within the City.
This sub -basin has a depressed region on the eastern portion of the sub -basin,
extending north -south throughout the sub -basin - see Figure 10-2.
—_ _Figure .1.0 2 —.Sub-basin_SB06.topographic trends.&.existingstorcnwater_infrastwcture
This sub -basin is bound on the north by SW 22nd Street and by South Dixie Highway on
the south. The east and west boundaries are SW 32nd Avenue and SW 37th Avenue,
respectively.
Similarly to sub -basin SB06, the main stormwater infrastructure components for the
interior portions of this sub -basin consist of isolated self-contained drainage systems
with exfiltration trenches. Large conveyance systems along SW 37th Avenue, SW 27th
Avenue, and South Dixie Highway provide conveyance capacity for those major
arterials, but these are predominantly County of FDOT drainage systems.
The peak stage and volume based on the model results for the 1.00-year, 72-hour for
this sub -basin are presented in Table 10-4. Additionally, the 25% and 50% goals for
___...this sub-basin„are also .shown .in .this table.
10-4
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
Table 10-4 — Sub -basin SB06 Stage Reduction Estimates
`=?e62 10.. a ,.. , 4 °Ezlstmg4.Gontlltron= _Y , v
' : :. s
100-year peak flood stage
• 11.30 ft-NGVD
100-year peak flood volume
391.01 ac-ft
• Number of flooded structures during •100-year design storm event
694
kV ,}�� A fL c.;:xg-40.:?5/°xFlopdedSIiuctTireMeduction,KI..
::±a. ° r__ ,- v
- Peak stage to reduce number of flooded structures by 25%
10.79 ft-NGVD
Peak volume to reduce number of flooded structures by 25%
294.81 ac-ft
"Total stage reduction
-0.51 ft
Total volume to be extracted
-96.19 ac-ft
Total reduction in the number of flooded structures at 25%
-174
R ,, �...
�...;�,'� .,.,, ��k.,�:��:50%,FloodednStruetUratf2e'ductlonSMOc.MZ
i,�,�%
Stage to Reduce number of flooded structures by 50%
9.88 ft-NGVD
Peak volume to reduce number of flooded structures by 50%
174.83 ac-ft
Total stage reduction
-1.41 ft
Total volume to be extracted
-216.18 ac-ft
Total reduction in the number of flooded structures at 25%
-347
As is the case for most 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. The City has already implemented
approximately 13,000 If of exfiltration trench in this sub -basin to provide for localized
flooding. This accounted for an estimated peak flood volume reduction of approximately
26.1 ac-ft based on the estimating methodology described for this SWMMP. This
volume is already accounted for in the totals in Table 10-4 through the models. In order
to provide for additional volumetric reductions, injection wells under gravity should be
provided in combination with the exfiltration trenches in areas with elevation. in excess of
8 ft-NGVD.
The proposed improvements for this sub -basin include the items listed in Table 10-5
and general locations for these improvements are shown schematically in Attachment
W-2.
Table 10-5 — Sub -basin SB06 Proposed Stormwater Management System Components
1 ,. s n I j
Ifem
"��. tea: ;�..... ;� .,,.: �N
TM 'A` ,
{ ty
-�_.Quantl .a,...'
Exfract►on'iVolume
�,. (alt.,
, -
1j},
A
4,-
-.,, 3 + r � ', _ s a etu ,
-, DescrptionkCort ments
Injection Wells
30
111.86 ac-ft
Will convey runoff to the groundwater.
;S'A r.GrA7citiLISystemF'CaOdd I6:40 ..,, W:,'h
P P.tP11:11,:86 aaft r ,,4',
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 approaching-0.51 ft.
10.3 Rank #3 - Sub -Basin SB25
Sub -basin SB25 topography indicates generally higher elevations than other areas
within the City. This sub -basin has generally flat grades with a depressed region on the
western side of the SW 22nd Avenue - see Figure 10-3.
10-5
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
Basin Boundary
Stormvater System
*Topography
High N
Figure 10-3— Sub -basin SB25 topographic trends & existing stormwater infrastructure
Sub -basin SB25 is bound by SW 8th Street on the north and approximately SW 16th
Street on the south. The east and west boundaries are SW 14th Avenue and SW .27th
Avenue, respectively.
The main -stormwater infrastructure components for-this-sub:basin-are -isolated-self-
contained drainage systems with exfiltration trenches on the east and west sides of SW
22"d Avenue. Additionally, an interconnected system along SW 22nd Avenue, from
Flagler Street to South Dixie Highway and onward to Biscayne Bay.
The peak stage and volume based on the model results for the 100-year, 72-hour for
this. sub -basin •are presented in Table 10-6. Additionally, the 25% and 50% goals for
this sub -basin are also shown in this table.
•
10-6
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
Table 10-6 — Sub -basin SB25 Stage Reduction Estimates
Mi:: K. x4 sM 334E �{. .y ..y Y i i p. y��54
.> .--�.4.�,ExistmgYCondtt�oni.,;r .�.r
.: i 3C 11 tl0 C'
- � .�.>� .. � < ' w4.: e
100-year peak flood stage
1.1.38 ft-NGVD
100-year peak flood volume
366.87 ac-ft
Number of flooded structures during 100-year design storm event
727
.;uy .,y "r .b y o k B '# ..J
�.�.�':;,��:�,.,,, ,� �.,,.�:25/o�Floodecl,Stnicture:Rer1'ucifon.._ ..
' ii.8a d," ri "ILL w s =(
,...<�� M,h.;.,-�` , A
Peak stage to reduce number of flooded,structures by 25%
10.85 ft-NGVD
Peak volume to reduce number of flooded structures by 25%
249.58 ac-ft
-Total stage reduction
-0.53 ft
Total volume to be extracted
-117.29 ac-ft
Total reduction in the number Of flooded structures at 25%
-182
I, t ? ,..,._ SO%'FloodeMtructure1Reduttion,;,
, ;A w,;e x,„
Stage to Reduce number of flooded structures by 50%
10.38 ft-NGVD
Peak volume to reduce number of flooded structures by 50%
164.07 ac-ft
Total stage reduction
-1.00 ft
Total volume to be extracted
-202.80 ac-ft
Total reduction in the number of flooded structures at 25%
•364
The proposed infrastructure in this sub -basin consists of systems of interconnected '
exfiltration trenches with injection drainage wells proposed west of SW.22nd Avenue'and
exfiltration trenches east of SW 22nd Avenue. The proposed improvements for this sub -
basin include the items listed in Table 10-7 and general locations for these
improvements are shown schematically in Attachment W-3.
Table 10-7 — Sub -basin SB25 Proposed Stormwater Management System Components
�.3
�Vicemc
.�A
�A
QuanUty
..EracloUo,.lum£_e
aac:z3
_ .
�N ` e'
,.DescrtpfonCommep ,...+
Exfiltration Trench
15,000-ft
30.12 ac-ft
Will provide additional interconnectivity within the sub-
basin as well as convey runoff to the groundwater.
Exfiltration trench will also be constructed..
Injection Wells
25
93.22 ac-ft
Will convey runoff to the groundwater.
g
- Total;System`;Capacity 12.4
.r 1123r34;acfts
x
The total removal capacity of the proposed improvements results in an estimated
reduction in volume just above the 25% flooded structure reduction target. This results
in an estimated reduction in stages of less than -0.53 ft.
10.4 Rank #4 - Sub -Basin SB23
The general topography for Sub -basin SB23 varies east to west within the sub -basin.
This sub -basin has a depressed region in the adjacent areas east and west of SW 22nd
Avenue, which is approximately four to five feet lower than the eastern part of the sub -
basin - see Figure 10-4.
10-7
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
Figure 10-4 — Sub -basin SB23 topographic trends & existing stormwater infrastructure
Sub -basin SB23 reaches from SW 27th Avenue to SW 12th Avenue and from SW 22nd
Street to north of SW 16th Street. This sub -basin follows some topographic ridges which
make up the border of the sub -basin - see Figure 10-4.
-Sub-basin SB23 -stormwater -infrastructure consists -of .several .self -contained -..systems
with exfiltration trenches, with some areas being serviced by larger interconnected
systems. An interconnected system also exists along SW 22nd Avenue, from Flagler
Street to South Dixie Highway and onward to Biscayne Bay. This system also appears
to be carrying runoff from sub -basin SB25, which is north of SB23.
•
The peak stage and volume based on the model results for the 100-year, 72-hour for
this sub -basin are presented in Table 10-8. Additionally, the 25% and 50% goals for
this sub -basin are also shown in this table.
10-8
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
Table 10-8 — Sub -basin SB23•Stage Reduction Estimates
. „A ro . ,.?g 1.i, "Resting gl3Tditlon i : t.., --
A7 -M `k;;iM..
•100-year peak -flood stage
11.38 ft-NGVD
100-year peak flood volume •
386.98 ac-ft
Number of flooded structures during 100-year design storm event
705
:�A.-,4g:.-�..-�.._.r�_ri_ �r25;/0, � oodedftrucfurelReduciton+�._�
x
" `" �`4
Peak stage to reduce number of flooded structures by.25%
10.83 ft-NGVD
Peak volume to reduce number of flooded structures by 25%
273.10 ac-ft
Total stage reduction
-0.55' ft
Total volume to be extracted
-113.88 ac-ft
Total reduction in the number of flooded structures at 25%
-176
't : y — BONE loodedE tructureIRenuctioi0_
, ,r,
t' ,`fry`.
Stage to Reduce number of flooded structures by 50%
10.11 ft-NGVD
Peak volume to reduce number of flooded structures by 50%
162.23 ac-ft
'Total stage reduction
-1.27 ft
Total volume to be extracted
-224.75 ac-ft
Total reduction in the number of flooded structures at 25%
-353
The topography within this sub -basin allows for the effective use of injection drainage
wells in areas around and above 8 ft-NGVD. The proposed improvements for this sub -
basin include the items listed in Table 10-9 and general locations for these
improvements are shown schematically in Attachment W-4.
Table 10-9 — Sub -basin SB23 Proposed Stormwater Management System Components
p y k �
fi,v'x
:. Item....:.. �
;_ ,: r."'iv'�ih
rQuanfity: ,.
�WExteacjon U.otume
- .., F
� .,(ac ft), . ,� w, €
y 'r' F� , � ?3n
£ ,.�� i F'Fa ` s 57''" } fix" ��;ya
�' -s., .. s DescriptionftComments:°; ' �.�... � .,.....
WIII provide additional interconnectivity within the sub -
basin as well as convey runoff to the groundwater.
Exfiltration Trench
20,000-ft
40.16 ac-ft
Injection Welis
20
74.57 ac-ft
Will help convey runoff to the groundwater.
i, ,.,,i1, tal.tSystem Capa6ity �;
w
' 4
114 73 iic`ftVII.
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 -0.55 ft.
10.5 Rank #5 - Sub -basin SB10
Although the topography for sub -basin SB10 is generally higher than other areas within
the City, this sub -basin does have a depressed region on the eastern portion of the sub -
basin, extending north -south across the sub -basin. This depressed region forms a
valley across the eastern portion of the sub -basin - see Figure 10-5.
10-9
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
Swrrrwa[er Sysem
'Topography
High N
Figure 10-5 — Sub -basin SB10 topographic trends & existing stormwater infrastructure
As is the case for most 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. The City has already implemented
approximately 2,300-If of exfiltration trench in this sub -basin to provide for localized
- `flooding. This accounted'for an estimated peak.flood'volume reduction of -approximately
4.6 ac-ft based on the estimating methodology described for this SWMMP. This volume
is already accounted for in the totals in Table 10-10 through the models. In order to
provide for additional volumetric reductions, injection wells under gravity should be
provided in 'combination with the exfiltration trenches in areas with elevation in excess of
8 ft-NGVD.
The peak stage and volume based on the model results for the 100-year, 72-hour for
this sub -basin are presented in Table 10-10. Additionally, the 25% and 50% goals for
this sub -basin are also shown in this table.
10-10
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
Table 10-10 — Sub -basin SB10 Stage Reduction Estimates
V.; ""*1ra:- b f. — zistingConditrontir,;_ inTOM, :K feM,_
100-year peak flood'staae
11.30 ft-NGVD
100-year peak florid volume
262.35 ac-ft
Number of flooded structures during_:100=year design storm event
511
_i.cs�.�.illiV.,....__., ,MR, 2-._ 25/o Flooderi;SfeuctuWf2eduction,.fits..
-_t EMSNSI.,:LE:
Peak stage to reduce number of flooded structures by 25%
10.71 ft-NGVD •
Peak volume to reduce number of flooded structures by 25%
167.54 ac-ft
Total stage reduction
-0.59 ft
Total volume to -be extracted
-94.81 ac-ft
Total reduction in the number of flooded structures at 25%
-128
�,..:�'� ,a�• �+.;SD,/o_Flonied 5tructuts;,ReductronattS.abi1
;, hOM
Stage to Reduce number of flooded structures by 50%
10.25 ft-NGVD
Peak volume to reduce number of flooded structures by 50%
108.95 ac-ft
Total stage reduction
-1.05'ft
Total volume to be extracted
-153.40 ac-ft
Total reduction in the number of flooded structures at 25%
-256
For this sub -basin, injection wells under gravity in combination with additional exfiltration
trenches 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 10-.11 and general locations for these improvements
are shown schematically in Attachment W-5.
Table 10-11'— Sub -basin SB10 Proposed Stormwater Management System Components
a =y � sr,.?
iiy #�tthA x
t
Item
erExtractron
L 4
w �`isJ fr E
,:Quantity
Volumi` `
�. if 3J°X'''� ?
',,. ' ,,�__ta -• •,,,, ,,.
�,�r�n L"6 x h
s �s € MJ� k ,,u { is I
"'aS } a Y" ? L.,..:,
x -._. f. DescctQtron/{Comtnen.a. _';
Will provide additional interconnectivity within the
sub -basin as wet as convey runoff to the
groundwater table.
Exfiltration Trench
2,000
4.02 ac-ft
Iniection Wells
25
93.22 ac-ft
Will convey runoff to the groundwater.
'[.�_' cital:System:Capialty iti a
l� na>, c.dtt"�:
: 97:24 aft ;;�"x~�
a.�,..a�+i4 � z �,�s:
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-0.59 ft.
10.6 Rank #6 - Sub -Basin SB04
Sub -basin SB04's topographic elevations vary from the sub -basin boundary to the
central area, where a depressed area is observed - see Figure 10-6..This sub -basin is
also bordered by the coastal ridge which borders the sub -basins in the South Biscayne
Basin.
Sub -basin SB04 is bound by South Dixie Highway on the north end and Main Highway
at the south. SW 37th Avenue and Virginia Street make-up the western and eastern
boundaries of the sub -basin.
10-11
February 2012
City of Miami
Phase II - Stormwater Management:Master Plan Final
LEGEND
Basin Boundary
Storm✓vater System
Figure 10-6 — Sub -basin SB04 topographic trends & existing stormwater infrastructure
The majority of this sub -basin's stormwater infrastructure components consist of self-
contained drainage systems with exfiltration trenches, with an interconnected system in
the south central area of the sub -basin that appears to continue southeastward
discharging to Biscayne Bay which is located south and east of this sub -basin. There
appears -to -be few -drainage facilities .at -the higher areas -of -the sub=basin; as -well -as -in
the lower elevation central areas.
The peak stage and volume based on the model results for the 100-year, 72-hour for
this sub -basin are presented in Table 10-12. Additionally, the 25% and 50% goals for
'this sub -basin are also shown in this table.
10-12
February.2012
City of Miami
Phase II - Stormwater Management Master Plan Final
Table 10-12 — Sub -basin SB04 Stage Reduction Estimates
e:.^'.bS Er5 WS...E,...;F.. axistmg Conditrdnm. r
100-year peak flood stage
11.30•ft-NGVD
100-year peak flood volume
278:08 ac-ft
Number of flooded structures during'100-year design storm event
416
EPTAritiPMEE : E 25% FloodecirStructu[eiReductton--: £
w..
..> ._ . 2F. a<
Peak stage to reduce number of flooded structures by25%
11:03 ft-NGVD
Peak volume to reduce number of flooded structures by 25%
219.21 ac-ft
• Total stage reduction '
-0.27 ft
Total volume to be extracted
-58.88 ac-ft
Total reduction in the number of flooded structures at 25%
-104
.1 '�, , �.',ti .. 5D%`cFlootledtstructureeductton �
,i<z;q „ritnk,M
Stage to Reduce number offlooded structures by 50%
10.59 ft-NGVD
Peak volume to reduce number of flooded structures by 50%
145.09 ac-ft
Total stage reduction
-0.71 ft
Total volume to be extracted
-132.99 ac-ft
Total reduction in the number of flooded structures at 25%
-208
Improvements for this sub -basin would most likely include a combination of exfiltration
trenches and drainage injection wells because this sub -basin lies within the saltwater
intrusion zone. The proposed improvements for this sub -basin include the items listed
in Table 10-13 and general locations for these improvements .are shown schematically
in Attachment W-6.
Table 10-13 — Sub -basin SB04 Proposed Stormwater Management System Components
; " r- � le
ra: ^ v �r _
�ta �'flfe ma���&�.:�},�aGtuanUty,
I
� Quan � .a
����
ti
_.,
�-"
Eztractio AVolume ,
4, n t " m' d
'� (
�..�... F .h: ac.ft)..�,��.,�`�Uu_.
� "�}
cr Slime _ Am3
D ..-
�'„_.. ,.. �5"�..,�c escelption/rGomments�.a._,� �.
Exfiltration Trench
11,000-ft
22.09 ac-ft
Will provide additional interconnectivitywithin the sub -
basin as well as convey runoff to the groundwater.
Injection Wells
' 30
111.86 ac-ft
Will help convey runoff to the groundwater.
_ :. <. T.otal Systaffi'Xapabity
'.'•,,
."4133!95sac,ftr
^"s
The total removal capacity of the proposed improvements results in an estimated
reduction in volume and stages which exceed the 50g/0 flooded structure reduction
target. This results in an estimated reduction in stages of more than -0.71 ft.
10.7-- -Rank #7 -Sub-Basin SB30
Sub -basin SB30 lies on a high topographic area with limited infrastructure providing
service to the area - see Figure 10-7. A depressed area exists along the southern
border of the sub -basin with a larger depressed area existing in the western portion of
the sub -basin east of SW 27th Avenue. In comparison to most areas in the City, this
sub -basin has generally higher elevations throughout the sub -basin.
10-13
February 2012
City of Miami
Phase.IJ - Stormwater Management Master Plan Final
;;LEGEND
QBasin Boundary
• - Stormwater System
..Topography
,.High l;
Figure 10-7 — Sub -basin SB30 topographic trends & existing stormwater infrastructure
This sub -basin is bordered on the north by NW 7th Street. On the south, this sub -basin
is bound from approximately NW 4th Street to NW .1st. The western edge of the sub -
basin is just east of NW 30th Avenue, while the east is bounded by a topographic ridge
located between NW 21st Avenue and NW 18th Avenue.
The main stormwater infrastructure components for this sub -basin are self-contained
drainage systems with exfiltration trenches located sporadically throughout the sub -
basin. There are two interconnected systems along NW 22nd and NW .27th Avenues,
from as far north as Flagler Street to South Dixie Highway and onward to Biscayne Bay
are also continuing from sub -basins north of SB30 primarily intended to service the
major roadways.
The peak stage and volume based on the model results for the 100-year, 72-hour for
this sub -basin are presented in Table 10-14. Additionally, the 25% and 50% goals for
this sub -basin are also shown in this table.
10-14
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
Tabfe.10-14 - Sub -basin SB30 Stage_Reduction Estimates.
ViZTIV ",`' krii,Ai ,,, w .,,v Egi5tirigte:di ditidnn:,M...
.f ?-.,.,...,ANx ; , ;'-
100-yearpeakflood stage_
13.17 ft=NGVD
100-year peak flood• volume
141.18 ac-ft
Number of flooded structures during'•100-year design storm event
338
1 •... .... __e _... ._.+-. NSCJ'
��L�1��°x:��'"�f�'�_"p:.��.+���=25%�F.,Iooded;St�ucturesReduction�;rs,�__
x" Y.:4F rrs7S. .Ti`RA E }
.tzF, ��,,5:;....?� .,.D„'
Peak stage to reduce number of flooded structures by 25%
12.50 ft-NGVD
Peak volume to reduce number of flooded -structures by 25%
87.50 ac-ft
Total stage reduction .
-0.67 ft
Total volume to be extracted
-53.68 ac-ft
Total reduction in the number. of.flooded structures at 25%
-85
a l,1TAM w k,: ME. -` 50%&FIooded;StructuretReduction :
r , :" 3 : f s ;._o
Stage to Reduce number of flooded structures by 50%
12.08 ft-NGVD
Peak volume to reduce number of flooded structures by 50%
59.50 ac-ft
Total stage reduction
-1.09 ft
Total volume to be extracted
-81.68 ac-ft
Total reduction in the number of flooded structures at 25%
-169
As with all the previous sub -basins, this sub -basin lies within the saltwater intrusion
zone. Therefore, improvements for this sub -basin would most likely include injections
wells under gravity due to the high topographic elevations in combiriation with
exfiltration trenches. The proposed improvements for this sub -basin include the items
listed in Table 10-15 and general locations for these improvements are shown
schematically in Attachment W-7.
Table 10-15 — Sub -basin SB30 Proposed Stormwater Management System Components
Ir I
l ifd`-�-\ <,,nyv+.,,Td4 £j-
Item t W� ;
-Est"
:7r, ..,� 'ts' ,.°SIP
.kQuantih!:
� ExtracfrorraVolume` r t,>
ffiS �t C ; W-?k`1'`ir
(BC.-ft1 ::ts'z_
��r a
�, xC�IE
i Ci'k ,a " k fir' j4. -"
tt`S I-e.#+..kt�s''.}g1z'w
:z,,-�Descnption/rCommen..#s,F.....n,,. 1
provide additional interconnectivity within the
sub -basin as well as convey runoff to the
table and provide for water quality
requirements.
Exflltration Trenches
10,400-If
20.88 ac-ft
Will
groundwater
Injection Wells
9
33.56 ac-ft
Will convey runoff to the groundwater.
.pn ..` t ..... .:.. ,T ,..._di +,� a - a xn „r e s t
.t•�.�tiz 4�Tofal SysfemsCapac�ty+.. ._. ,...,.?t.:...� 54.44Lac.ft;,a�, at:
The total removal capacity of the proposed improvements results in an estimated
reduction in volume and stages equal to the 25% flooded structure reduction target.
This results•in an estimated reduction in stages of approximately -0.67 ft.
10.8 Rank #8 Sub -Basin SB13
Sub -basin SB13 is also represented in Phase I of this SWMMP as sub -basin DA1-SE-2.
With the creation of the Phase II XP-SWMM models, it was determined that this sub -
basin appears to be a part of the South Biscayne basin and contributes to the hydraulic
systems analyzed under Phase II. Additionally, the limits of this sub -basin were
reevaluated and revised as presented in Phase II and the proposed projects to follow
were revised to these new limits. This sub -basin will be ranked as a single sub -basin
based on the results from Phase II as sub -basin SB13.
10-15
February 2012 City of Miami
Phase II - Stormwater Management Master Plan Final
This sub -basin's topographic elevations are generally higher than the surrounding areas
to the south and west see Figure 10-8: The northern portion ofthe sub -basin shows
higher --elevations: than:. the .southeastern portions .of the -sub-. - A low. -lying... area exists in
the southwestern limits of the sub -basin.
;iLEGEND
QBasin Boundary
-.Storm rater System
Figure 10-8 — Sub -basin SB13 topographic trends & existing stormwater infrastructure
The main stormwater infrastructure components for this sub -basin show some
interconnectivity throughout the sub -basin although the lower areas show limited
infrastructure. This sub -basin is primarily serviced by self-contained systems with
exfiltration trenches 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 allows 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 10-16. Additionally, the 25% and 50% goals for
this sub -basin are also shown in this table.
10-16
February 2012
City of Miami
Phase II -Stormwater Management Master Plan Final
Table..10-16 -.,Sub-basin SB13_Stage..Reduction Estimates
��..,,-��_,_��,:,,a�..;��,,....,.,��S3=xistingsCondrtion�. � _ _ �.. �'�..._ 'fix ��
�KWr'Ma'avr P '.1'r„",1 A ..' xY `- - 1$xY"". yuy , `}_kentt;Ys`+"�L ;nwn I., yA.-.ra',';
100-year peak flood stage
11.30 ft-NGVD
100-year peak flood volume
132.92 ac-ft
Number of flooded structures during .100-year design storm event
219
R '"i�"i, .}.,f t� ✓�.fi .:i^ 1 r.p o . f .. .e .. - ^x' ti
.,w`'s��z.��_ �,,�:K�,#:,2fi/o:Flooded,Stiucture.i2eduction
Y{ . l Y2. .. _.
��.��3�r� _:.!��,ia�._-_
Peak stage to reduce number of flooded structures by 25%
10.86 ft-NGVD
Peak volume to reduce humber.of flooded'structures by 25%
97.54 ac-ft
Total stage reduction
-0.44 ft
Total volume to be extracted
-35.39 ac-ft
Total reduction in the•number of flooded structures at.25%
-55
i rtC . Psi. t ri ...-t .! 0 -,- ...- f .u.... ... v L .f�
._..._.,....�v�..n...P• ,:r_� ��50%,Flooded�5t�ucture�Retluctton._:�t,:�.,,,r�:..,,�
r _ 4 .:*i11 :.
�.,:,� ,�,�t..5..�a
10.16 ft-NGVD
Stage to Reduce number of flooded'structures by 50%
Peak volume to reduce number of flooded structures by 50%
59.20 ac-ft
Total stage reduction
-1.14 ft
Total volume to be extracted
-73.72 ac-ft
Total reduction in the number of flooded structures at 25%
-110
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 10-17
and general locations for these improvements are shown schematically in Attachment.
W-8.
Table 10-17 - Sub -basin SB13 Proposed Stormwater Management System Components
mt x
,a'
iltem� k
`- �
uant
Vractiooume"
,4. sS
,�acf) .�i
+r ��kT^ �P am'�1;t�
, LDecrroCoest"
�-frJ-+
Injection Wells
20
74.57 ac-ft -
V ill convey runoff to the groundwater table.
119:-.;, z; zTotal"System Capacity.
;i'`, rc.;7
*w- i. 74f57 ac ft
The total removal capacity _of_the proposed improvements results inan estimated
reduction in volume and stages equal to the 50% flooded structure reduction target.
This results in an estimated reduction in stages of approximately -1.14 ft.
10.9 Rartk #9 - Sub -Basin SB14
Sub -basin SB14 has a depressed topographic area which bisects the sub -basin
diagonally from northwest to southeast - see Figure 10-9. The depressed area is west
of SW 22nd Avenue with a smaller depressed area to the east. The southwestern and
northeastern portions of the sub -basin lie on higher elevations relative to the depressed
area.
Sub -basin SB14 is bordered by South Dixie Highway to the south, SW 27th Avenue to
the west and approaches SW 19th Avenue to the east. The northern limits vary to as far
north as SW 22nd Street.
10-17
February.2012
City of Miami
Phase II - Stormwater Management Master Plan Final
LEGEND
0 Basin Boundary
- Starrwater System
Topography
High N
Low
Figure 10-9 — Sub -basin S614 topographic trends & existing stormwater infrastructure
The main stormwater infrastructure components for this sub -basin are comprised of
several self-contained systems with exfiltration trenches, in addition to the
interconnected system at SW .22nd Avenue, which collects runoff from the depressed
area to the west within the sub -basin. This interconnected system appears to be part of
----the interconnected system 'that -begins at'Flagler Street and' travels southward 'to South
Dixie Highway discharging into Biscayne Bay.
The peak stage and volume based on the model results for the 100-year, 72-hour for
this sub -basin are presented in Table 10-18. Additionally, the 25% goals for this sub -
basin are also shown in this table.
10-18
February.2012
City of Miami
Phase II -Stormwater Management Master Plan Final
Table 10-18— Sub -basin SB14 Stage Reduction Estimates. •
- w a <E- iEiustih3G'onditiisfen
a s
x r . i; ,
u_
100-year peak flood.stage .
11.25:ft-NGVD
. 100-year peak -flood volume
194.56 ac=ft
Number of flooded structures•during :100-year design storm -event
.. 328 ,'
.. , z I. ER 25%:F<tooled'sfeucturexReductio-61. E� ;
,_ ., . al ".
_'"'
Peak stage to reduce number of flooded structures by 25%
10.78 ft-NGVD
Peak volume to reduce•number of flooded structures by 25%
145.28• ac-ft
' --Total stage reduction
,0:47ft
Total volume to be extracted
-49.28 ac-ft
Total reduction in the number of flooded''structures at 25%
• 482
4.kir5MT.M1 eS0%1Flooded Structure Reduction
Kri
, ,
.7,.
Stage to Reduce number of flooded structures by50%
10:00 ft-NGVD
Peak volume to reduce number of flooded structures by 50%
88.40 ac-ft
Total stage reduction'
-1.25 ft
Total volurne to be extracted
-106:16 ac-ft
Total reduction in the number of flooded structures at 25%
-164 •
This sub -basin would benefit from an increase in capacity in the depressed area of the
sub -basin to help convey runoff to the interconnected system along .SW .22nd Avenue.
To accomplish this, an exfiltration trench system west of SW 22nd Avenue and a'
combination of injection wells and exfiltration trenches on the north end of the sub -basin
should reduce flooding in the sub -basin. The proposed improvements for this sub -basin
include the items listed in Table 10-19 and general locations for these improvements
are shown schematically in Attachment W-9.
Table 10-19 — Sub -basin SB14 Proposed Stormwater Management System Components
`•..
�r -.Item ,
a`"nExtta�ction�Volume
r Quantity
y
,,� 4 tom'{ac,ft}� r, sr 4'a .3
s 4 r ' ,, Y e •k r , t; r
_: _ t � DesprfpironI Commenfs "` ._ a
Exfltration Trenches
15,000-If
30.12 ac-ft
Will provide additional interconnectivity within the sub -
basin as well as convey runoff to the groundwater.
Iniection Wells
25
93.22 ac-ft
Will convey runoff to the groundwater table.
„ 'rotaLSysfem.Capacity >€0-,
�5P.::±�.123 34ac ftWiM.:i.
The total removal capacity of the proposed improvements results in .an estimated
reduction in volume and stages above the 50°/0 flooded structure reduction target. This
results in an estimated reduction in stages of more `than1-25'ft.
10.10 Rank #10 - Sub -Basin SB34
This sub -basin has topographic elevations which are generally higher than the majority
of the sub -basins within Phase II's South Biscayne basin. This sub -basin has some.
minor depressed areas located in the interior portions of the sub -basin - see Figure
10-10.
Sub -basin SB34 is bound by NW 2nd Street at its north, SW 11th Street at the south, 17th
Avenue on the west, and SW 11 th Avenue on the east. The lowest topographic
elevations are between West Flagler Street, south to SW 4th Street, between SW 17th
Avenue and SW 14th Avenue.
10-19
February 2012
City of.Miami
Phase II - Stormwater Management Master Plan Final
Figure 10-10 — Sub -basin SB34 topographic trends & existing stormwater infrastructure
This sub -basin contains an interconnected drainage system with exfiltration trenches
throughout the majority of the sub -basin. Improvements to this sub -basin would consist
of upgrading existing infrastructure by adding exfiltration trench and adding drainage
wells to provide additional conveyance capacity to the groundwater table.
The peak stage and volume based on the model results for the 100-year, 72-hour for
this sub -basin are presented in Table 10-20. Additionally, the 25% and 50% goals for
this sub -basin are also shown in this table.
10-20
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
Table 10-20 — Sub-basin.SB34..Stage Reduction Estimates
amai,. - we n .,a..y ",nExistmg aaediiron , { MIF
100-yearpeak flood stage
11.38 ftNGVD
. 100=year peakflood volume
147.57 ad-ft
Number of flooded structures during`100.-year design.storm event
304
ti= , T. :44,57, .:425%.FioodecltSfEucture RaiiuctionZ4Wt
i4 ., 2iiVE EnT14
Peak stage to reduce number.of flooded structures by 25%
10.85 ft=NGVD
Peak volume to reduce number of flooded structures by 25%
98.48 ac4t
"Tbtal`stape reduction"
-0.53`ft
Total volume to be extracted
-49.09 ac-ft
Total reduction iri the number of flooded structures at 25%
-76
"
LSD°CIFlootletl StruetureliRe'ductroftil
__Z "s"
' ; t<t
Stage to -Reduce number of flooded structures by 50%
10.37 ft-NGVD
Peak volume to reduce number of flooded structures by 50%
62.89 ac-ft
Total stage reduction
-1.01 ft
Total volume to be extracted
-84.68 ac-ft
Total reduction in the number of flooded structures at 25% '
-152
The proposed improvements for this sub -basin include the items listed in Table 10-21
and general locations for these improvements are shown schematically in Attachment
W-10.
Table 10-21 — Sub -basin SB34 Proposed Stormwater Management System Components
sq §� £ � r,
iyk. Y it �°. a RV kf s
ai=' cr _rltem
< <1,, ,;, ;
f T;:
� Qua
,t ExtractronaVotume
SRI:� t w% •p 4 iS�fi +�'11
l r�..rr':;�{ac ft)., f- .�.s,4
�s � r r �" ,„ w: " kr, } x .i ss
F ix } ' }� i'�
t ,, �Descriptrenl„C,omn+ents i gs o,;
Will provide additional interconnectivity within the
sub -basin as well as convey runoff to the
groundwater.
Exflltration Trenches
6,000-If
12.05 ac-ft
Injection Wells
20
74.57 ac-ft
Will convey runoff to the groundwater table.
fE42: ii:,aTotal:System;CapacrtMg", ' M
R.486:62xac-ffZTR
The total removal capacity of the proposed improvements results in an estimated
reduction in volume of approximately the 50% flooded structure reduction target. This
results in an estimated reduction in stages above -1.01 ft.
10.11 Rank #11 - Sub -Basin SB33
Sub -basin SB33 is also represented in Phase I of this SWMMP as sub -basin CC6-S-8.
With the creation of the Phase II XP-SWMM models, it was determined that this sub -
basin appears to be a part of the South Biscayne basin and contributes to the hydraulic
systems analyzed under Phase II. Additionally, the limits of this sub -basin were
reevaluated and revised es presented in Phase II and the proposed projects to follow
were revised to these new limits. This sub -basin will be ranked as a single sub -basin
based on the results from Phase II as sub -basin SB33.
This sub -basin's topographic elevations are generally higher than the surrounding sub-
_ aSinS.to_the_nD.rth _and wes.t__s.ee...Figure 1.0-11-_.The no.dheas.te.rn_po.r#io.n_c.f_th.esub-
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. A large portion of the sub -
basin appears to form a somewhat level plateau throughout much of the sub -basin.
10-21
February.2012
City of Miami
Phase ll - Stormwater Management Master.Plan•Final
LEGEND
•
= Basin Boundary
Stormwater System
Topography
Figure 10-11— Sub -basin SB33 topographic trends & existing stormwater infrastructure
The main stormwater infrastructure components for this sub -basin appear to be various
sections of stormwater infrastructure with exfiltration trenches primarily in the northern
half of this sub -basin although no major lines run within the body of the sub -basin and
no major lines appear to be discharging outside of the sub -basin. This sub -basin
primarily lacks interconnectivity within the sub -basins systems to the main conveyance
systems discharging to the C-6 Canal which 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 10-22. Additionally, the 25% and 50% goals for
this sub -basin are also shown in this table.
10-22
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
Table 10-22 — Sub -basin. S633:Stage Reduction Estimates .
, - „., Ektsting ondit.on' �" ;:t .: sy l +I 8ft- °`AVAIw.�`I
100-year peak'flood stage
1.1:28 ft-NGVD •
100-year peak flood volume
225.03 ac-ft
Number of flooded structures during:100-year<design storm event
322 -
x. .;
_. .��„,aas:r.Zb,/obFlooded Structurwzeductionzani._;`
ta,�
Peak stage to•reduce number of.flooded.structures by 25%
11.05 ft-NGVD
Peak volume to reduce number of flooded structures by 25%
173:18 ac'ft
Total stagereduction
-0.23 ft-
Total volume to be extracted
-51.85 ac-ft
Total reduction in the number of flooded structures at 25%
-81
, .
? `s , r 3 t 50MR�IoodedttStructuree"ReCuction"k '-
M -4
' a "t p� ,,,,...,
Stage to Reduce number of flooded structures by 50%
10.77 ft-NGVD
Peak volume to reduce number of flooded structures by 50%
123.01 ac-ft
Total stage reduction
-0.51.ft
Total volume to be extracted
-102:02 ac-ft
Total reduction in the number of flooded structures at 25%
-161
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 10-23
and general locations for these improvements are shown schematically in Attachment
W-11.
Table 10-23 — Sub -basin SB33 Proposed Stormwater Management System Components
:z. �
;. u _Item z,
�` 3 -. ;' _dT. $d
f"+uanfit}
.C,yx �Y E:�tra loin oltr i$ ualr'�z
,ac fit} ks
if e", �'f. , ' fi 3iv 'w 4, _ aL'b"s rv. s ,_ ''. .+ram ':, 19i
!"3T. ,.bescriptionbcomments_.>,.,. fir_
Will provide additional interconnectivity within the
sub -basin as well as convey runoff to the
groundwater and provide for water quality
requirements.
Exfiltration Trench
4,000-If
8.03 ac-ft
Iniection Wells
30
111.86 ac-ft
Will convey runoff to the groundwater table.
,. 7Tetal;$:ystemnCapacityOi, r.• ` '
c11:9189:acyftsW O:: I
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 -0.51 ft.
10.12 Rank #12 - Sub -Basin SB28
This sub -basin's topographic elevations are generally high on the western portion of the
sub -basin than on the eastern portion with a depressed area on the eastern limit of the
sub -basin - see Figure 10-12.
10-23
February 2012
City .of: Miami
Phase II-.Storm.water.Management;Master Plan:Final
Basin Boundary
Storm✓rater System
Topography
High N
Figure 10-12 — Sub -basin SB28 topographic trends & existing stormwater infrastructure
This sub -basin contains minor isolated self-contained drainage systems with exfiltration
trenches throughout the sub -basin. However, the main stormwater infrastructure for this
sub -basin consists of the interconnected trunk line along SW .22nd Avenue, which
collects runoff from as far north as West Flagler Street and continues southward
collecting runoff from adjacent areas and discharging into Biscayne Bay.
The sub -basin's northern boundary varies between SW 1st Street and SW 4th Street.
The boundary to the south is located along SW 8th Street, while the west and east
boundaries are at SW 27th Avenue and SW 17th Avenue, respectively.
The peak stage and volume based on the model results for the 100-year, 72-hour for
this sub -basin are presented in Table 10-24. Additionally, the 25% and 50% goals for
this sub -basin are also shown in this table.
10-24
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
Table 10-24 — Sub -basin SB28 Stage.Reduction Estimates
AR"{{2 p 1--.`,,,,p``y iii et a }r` "F =rEzistiittCbndlti9nZ..,r
'
x'
100-year peak flood stage'
11.35 ft NGVD "" "
100-year•peak flood.. volume
124:47 ac-ft
Number of flooded structures during1T00-year design storm event
'' 260'
a€5+44025°/ Flooded°.StructurefRetluction
giag4 "
.v.
Peak stage to reduce number:of flooded structures by:25%
1 a92 ft=NGVD
Peak volume to reduce:number of:flooded structures by 25%
• 83:43-ac-ft
-. .. Total°stage reduction'._ •
.•-0:46-ft
Total volume to be extracted
-41.04 ac-ft
Total reduction in the numberof flooded structures'at.25%
-65
- kk
n�,a,�.�',,�,4�.'�'?z��%�.SD°/D`�FlootledtStructure�aReductioh
a .� �; `�;�,�F
'r
i3y.
Stage to Reduce number of flooded structures by 50%
10.46 ft-NGVD
Peak volume to reduce number of flooded structures by 50%
50.15 ac-ft
Total stage reduction
-0.92 ft
Total volume to be extracted
-74.31: ac-ft
Total reduction in the number of flooded structures at 25%
-130
This sub -basin would benefit from additional exfiltration trench on the east side of the
sub -basin, east of SW 22nd Avenue, to discharge runoff into the groundwater at the
lower lying areas prior to reaching the interconnected system along SW 22nd Avenue.
Additional exfiltration trenches should also be added, along with drainage wells, west of
SW .22nd Avenue. The proposed improvements for this sub -basin include the items
listed in Table 10-25 and general locations for these improvements are shown
schematically in Attachment W-12.
Table 10-25 — Sub -basin SB28 Proposed Stormwater Management System Components
s ,
imo- Za_`f", Yt
"�.em
u , i+
`
T,._Quantlty�,
� ,g lo.e
tSitractforitVlum'zp
, rT ? (ara i'
S
escnptit) oxim' mk'Se. nY t L`3 'S.
1 -�:
Exfiltration Trenches
8,000-If
16.06 ac-ft
Will provide additional interconnectivity within the
sub -basin as well as convey runoff to the
groundwater.
Injection Wells
20
74.57 ac-ft
Will convey runoff to the groundwater table.
;: 316talSystemaCapacitifig ;"; ,,; r'
at j901764461:0M113
The total removal capacity of the proposed improvements results in an estimated
reduction in volume and stages which exceeds the 50% flooded structure reduction
target. This results in an estimated reduction in stages above -0.92 ft.
10.13 Rank #13 - Sub -Basin SB20
Sub -basin SB20 is also represented in Phase I of this SWMMP as sub -basin C5-S5-3.
With the creation of the Phase II XP-SWMM models, it was determined that this sub -
basin appears to be a part of the South Biscayne basin and contributes to the hydraulic
systems analyzed under Phase II. Additionally, the limits of this sub -basin were
reevaluated and revised as presented in Phase II and the proposed projects to follow
were -revised -to .these -new -limits.- This sub -basin will -be ranked as -a-single .sub -basin
based on the results from Phase II as sub -basin SB20.
This sub -basin's topographic elevations are generally higher than the surrounding sub -
basins to the north and .west -.see Figure 10-13. The northwestern portion of the sub-
10-25
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
basin..:shows lower elevationsthan the southeastern portion of:the sub -basin although
they are higher than the elevations of the subbasin to the. -north..
.EGEND
QBasin Boundary
Stormwater System
-Topography
High N
Figure 10-13 — Sub -basin SB20 topographic trends & existing stormwater infrastructure
The main stormwater infrastructure components for this sub -basin are localized sections
of stormwater infrastructure--with-exfiltration trenches within-this-sub=basin—No-major
drainage trunk 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 lacks 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 10-26. Additionally, the 25% and 50% goals for
this sub -basin are also shown in this table.
10-26
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
Table 10-26- Sub -basin SB20Stage Reduction Estimates
.a "... ilia =l a Iaxistmg ifi ditioh; ' 11 .,_ -
I .d'' s
t
• 100-yearpeak•flood stage '
11.38-ft-NGVD
100-year peak flood volume':. •
111.46 ac-ft
Number of.flooded structures during 100 year design storm event
302
.,aiten,,;;,2574FloodedrStructur4Reductionraa-ln„
, .:�wP�:�,.
_�.�
Peak stage to reduce number of flooded structures by 25%
11.09 ft-NGVD
Peak volume to reduce number of flooded structures by.25%
82.43'ac-ft
Total:stagereduction
-0.29 ft
Total volume to be extracted
-29.03 ac-ft
Total reduction in the number of flooded structures at 25%
-76 ,
gene "_.. , ill50olo.,Flo IleetZtr'uct iteaCtidi ction 'i
V.
'
Stage to Reduce number cif flooded structures by 50%
10.71 ft-NGVD
Peak volume to reduce number of.flooded structures• by 50%
'51.29 ac-ft
Total stage reduction'
-0.67 ft
Total volume to be extracted
-60.17 ac-ft
Total reduction in the number of flooded structures at 25%
-151
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. Injection drainage wells are not feasible due to the sub -basin
being outside the saltwater intrusion zone.
The proposed improvements for this sub -basin include the items listed in Table 10-27
and general locations for these improvements are shown schematically in Attachment
W-13.
Table 10-27— Sub -basin SB20 Proposed Stormwater Management System Components
Exfiltration Trenches
r=
uan
15,800-If
eotal. ystem:,rapacity„r.
xtractionjV.oIurn
31.73 ac-ft
31:�3 ac-if'
ascription/ Comments3
Will provide additional interconnectivity within
the sub -basin as well as convey runoff to the
groundwater.
The total removal capacity of the proposed improvements results in an estimated
reduction in volume and stages which is above the 25% flooded structure reduction
target. This results in a estimated reduction in stages of -0.29 ft.
10.14 Rank #14 •- Sub -Basin SB18
This coastal sub -basin lies next to Biscayne Bay and lies just south of a coastal ridge
located in this area. Its topographic elevations are high, north of South Bayshore Drive
-and-low, south -of -South Bayshore Drive see Figure-10-14-
10-27
February.2012
City of Miami
.
Phase II Stormwater.Management;_Master:Plan:Final
LEGEND .
QBasin,Boundary
- Storrrwater System
Figure 10-14 — Sub -basin SB18 topographic trends & existing stormwater infrastructure
Stormwater infrastructure components for this sub -basin are isolated drainage systems
south of South Bayshore Drive with positive outfalls draining directly into Biscayne Bay.
Few drainage systems are noted on the north western portions of the 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 10-28. Additionally, the 25% and 50% goals for
this sub -basin are also shown in this table.
10-28
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
Table 10-28— Sub -basin SB18 Stage Reduction, Estimates..
' :,, m i, i-Af ' ' ,.,,,t,i,t' ., t Exiotmg, Conan r9n k:, imm.nwar,, t ,kaixwev
.-.._..100-year`peaR:floodstage......_:..__..,....-�..-_:
,......_5:72'ft-NGVD......
100-year peak fldod•volume
179' 95-ac'ft
Number of flooded:structures.'during'100-yeardesign storm event
'126
maligratan,, %.2.04M ", 25%'FlnodetPStructurelReductioni it ,
, :". -!, : 'k rI2ifiV? G_.
Peak stage to reduce number offlooded structures by 25%
5:14 ft-NGVD
Peak volume to'reduce numberof.flabded structures•by'25%
126:00.ac-ft
---•Total-stagereduction • . -- ' •
- 4158 ft• ••
Total .volume to be extracted
-53.94 ac-ft
Total reduction in the!riumber.of.flodded.structures at 25%
•=32
iir r LF.ke.m.;' :;. `,nip" t)°/ Efrigded"Structure3Re ffetmoiVik
- , , s k, s ?; A
Stage to Reduce number of flooded structures by.50%
3.20 ft-NGVD
Peak volume to reduce number of flooded structures by 50%
31.96,,ac,ft
Total stage reduction
-2.52 ft
Total volume to be extracted
-147.98 ac-ft
Total reduction in the number of flooded structures at 25%
-63
The high topographic elevations would allow for efficient operation of • exfiltration
trenches and injection .wells throughout the north western portions of the sub -basin
although the south eastern portions of the sub -basin do not have the topographic
elevations necessary to effectively utilize similar systems. Because of these low
topographic elevations, pump stations will be required to expedite flows to the
groundwater or to Biscayne Bay, as needed. The proposed improvements for this sub -
basin include the items listed in Table 10-29 and general locations for these
improvements are shown schematically in Attachment W-14.
Table 10-29 — Sub -basin SB.18 Proposed Stormwater Management System Components
Pump Station
Force Main
anti
3
2,100-If
�Extractron,"Voiuniep
c� ,t(ac ft)ra�t
0.00 ac-ft
0.00 ac-ft
Desdrrptmoomments
i.,
t N C-Ir:�sz,w'' lea .:�.i-ter 1�'•.v�'Yi�...
Pump stations of 15,000 gpm to increase the
hydraulic grade line for the wells and to increase
peak flow rates to Biscayne Bay.
Force main to connect pump stations to injection
wells.
Iniection Wells
20
'" z,.,. .Tot irsystemrcaPacitOt+',} i;^i,g
h
74.57 ac-ft
;74r574ac ft :i';
Will convey runoff to the groundwater.
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 beyond -0.58 ft.
10.15 Rank #15 - Sub -Basin SB12
This sub -basin's topographic elevations are generally lower for the main portion of the
sub -basin to the north - see Figure 10-15. The portion of the sub -basin which borders
SW 27th Avenue is generally higher than the low lying northern portion of the sub -basin.
10-29
February.2012
City of Miami
Phase II - Storrnwater Management Master�Plan.Final
[ EGEND
Basin Boundary
Stormwater System
Figure 10-15 — Sub -basin SB12 topographic trends & existing stormwater infrastructure
The main stormwater infrastructure component for this sub -basin is the drainage system
serving SW 27th Avenue. This system continues southward collecting runoff and
discharging into Biscayne Bay. This system does not extend to the low-lying area to the
northeast of the sub -basin. A small self-contained system is present in the northeastern
area Of the 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 10-30. Additionally, the 25% and 50% goals for
this sub -basin are also shown in this table.
10-30
February 2012
City of Miami
Phase II -Stormwater Management Master Plan Final
:Table 10-30.— Sub -basin SB12.Stage Reduction. 'Estimates..
-,- oge...ggisung:oziwoitioftw Te
Si ",n , ,tv
:•'.100-Year-peakflood stage.,.___._._�..___....�.._ .•.
"• � •11°25ft=NGVD" _
100=yearpeak`flood volume.„ •
166.09 ac=ft
Number of flooded structures dunn$.100 year•design:storm event
183
^'74 n,'yy� h .I' tga: 7,25.Nrt'. _ i -...� _.__ vv4,(
.^.Fi�`xt�u,!?�L �;Ip.eF:-€; h���:�;�Y"'.2:±k,:S�•LJt/OFFlootled Stiucfureiiteduct€on�`.?.aF
W". ,w . Iv. 3 iS4Syy Y'4. v�r�
.:. d.. ."'�'�cl'.-"�:�.�'�'.�h.�S`e- •r _, „:.'.lE
Peak stageto reducenumberof:flooded'structures by:25%
10:38.ft-NGVD
Peak volume to reducetnumber of flooded:str€ictures by 25%
112:88:ac=ft
"- Total-stagereductioh - `-- .•• --
•=0.87<ft-
Total volume to be extracted
-53:21-ac-fi
Total reduction in:the number of flooded structures at 25%
-46 -
taeglte, ik '_ ,M - : ,% Floaiied Sferieture Retluct€bit
N#, `aim rItf l »t
Stage to Reduce number of flooded structures by 50%
9.45 ft-NGVD
Peak volume to reduce number -of flooded structures by 50%
68:72 ac-ft
Total stage reduction ..
-1:80 ft
Total -volume to be extracted
-97.37 ac-ft
Total reduction in the number of flooded structures at 25%
-92
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. Additional interconnectivity will also help in equalizing the stages once
improvements are constructed.
The proposed improvements for this sub -basin include the items listed in Table 10-31
and general locations for these improvements are shown schematically in Attachment
W-15.
Table 10-31 — Sub -basin SB12 Proposed Stormwater Management System Components
" 4lEp »
. si rA 3_.
ate } Item E� '
VIA' �
» YLS" ' s-t
? Auant.
. , iaet€an'Vol
;•y '¢ m 5 m J L Eq a. Si
» :.k, ��+ taCffi f,t
,ipttoN Cnmmentst r ,
e .g' F ;.0 t '`��`"., "`+
� s tlai
Exfiltration Trenches
6,000-If
12.05 ac-ft
Wit provide additional, interconnectivity within the
sub -basin as well as convey runoff to the
groundwater table.
Injection Wells
15
55.93 ac-ft
Will convey runoff to the groundwater.
_; 1 ;T ital:Systemr.Cep ditAViKift
w:::.a `Tx`�,`-6.7. 98AadfftW, _g
•
The_total._r.emov.al _.capacity..._o.f.._the .pr.oposed Jrrmpr.ov_emenfs._res.ults_in_an_esiimated
reduction in volume and stages which exceed the 25% flooded structure reduction.
target. This results in an estimated reduction in stages beyond -0.87 ft.
10-31
February 2012
IN$
City of Miami
Phase II - Stormwater;Management Master Plan Final
Stormwater management .systems were devised for each of -:the :top 15 ranked aub-
basins within the Phase II SWMMP limits of the City of Miarrii. 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:for each of
-the top 1"5 ranked sub -basins can be seen schematically in: Attachment W. The
stormwater management systems proposed for these sub -basins may be constructed in
phases depending on funding availability and engineering design and permitting
constraints.
11.1 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.
These driving factors resulted in the majority of the construction cost for these projects
being around $2,000,000. Some projects such as pump stations with drainage wells
may exceed this total cost.
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
City of Miami current bid pricing records
In addition to the planning -level construction direct cost subtotal shown for each sub -
basin, maintenance of traffic, mobilization, CIP management, construction
management, permits, survey, design, and construction contingency were also included
in the planning -level -construction -cost total -and presented,as-follows:
• Planning -level 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
• Planning -level 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 X provides a listing of all projects by sub -basin with each of these items
detailed in the table,
February 2012
City of Miami
Phase II - Stormwater Management Master Plan Final
11.2...Cost:Estimate Results
A, summary o.f.the...Planning-level_Construction Costs.. per.... sub -basin is shown in Table
•1'.1 -1`and detailed planning -level construction costs with unit quantities for the grouped
projects are presented in Attachment X. Each project referenced in this table -refers -to
the projects shown schematically in Attachment W: It should be noted that the nature
and -extent of the -majority of these proposed projects allow.for furtherphasing-within the
project in order to allow for the funding allocations for the design and construction.
Table 11-1 — Planning -level construction costs per.sub-basin
�kh
FI oti �
5
0,,, 4. k
�
R _� � ��
r
�, ub hasin
tannm (even. �.�
Constructio Oost
� xr:. Totaig
1
SB09
$15,511,031
2
SB06
$3,405;188
3
SB25
$11,473,963
4
SB23
$13,753,919
5
SB10
$4,006,681
6
5E304
$9,722,213
7
SB30
$6,995,381
8
SB13
$2,270,125
9
SB14
$11,455,194
10
SB34
• $5,720,894
11
SB33
$6,134,700
12
SB28
$7,192,900
13
SB20
$9,081,394
14
SB18
.$7,155,363
15
SB12
$5,153,363
The total of all of the projects presented for the top 15 ranked sub -basins within Phase II
of this SWMMP is just over $119,000,000. Over 5-years, the average yearly funding
allocation requirement would approximately $24,000,000 for Phase II if all projects were
to be constructed with the 5-year period.
11-2
Februa,ry..2012
;j• .
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 planning -level construction cost and weighing that cost
versus the number of properties benefiting from the improvement. This procedure and
the revised sub -basin ranking are described further in the following subsections.
12.1 Ranking. Procedure & Results
The ranking procedure was based on two components that help to identify 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:
City. of Miami
Phase 11;-.Stormwater Management Master Plan Final
• Level 1 More than 300 properties affected and more than 50% 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_b.ased_on the_cost__ ofthe
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 that affect the highest number of properties at
the lowest cost per structure. The planning -level construction costs per sub -basin
developed in Section 11.0 were used for this portion of the ranking procedure.
The sub -basins were then ranked by the Importance Factor and then by the Cost per
Flooded Property Removed from Flood Plain, This new ranking helps identify which
sub -basin's groups of improvements will provide the highest return in terms of flood
_. _protection at_fhe_lo.wesf.cost. The_revised_ranking _is _presented _in_Table_12-1
None of the sub -basins within Phase II fall within the Level 1 Importance 'factor due to
the quantity of homes which are estimated to be removed from the floodplain based on
the proposed improvements.
12-1
February 2012
City of Miami
Phase II - Stormwater Management'Master Plan Final
.Table 12 ;1 R.evised_Rapk.ing.of_ tpse,ll Sub. -basins.
rye F
tr -
Flootl3
i'i4.
Rank
� ��•
;fis3xm�pr.
s
u
*-5ub.TA
� ��
basin
' ' fi �`�
t�,��"--s
} fbtta
itt+�vy. p
Plannin level
,' a 4. '
�xconstruction
t td
�Cost Total"�"*
� _a+&F y� r�?a
`�
tl
x
ONOt t
;4M -gr��
Pro etfles,
�,� �� �
_�i^ k4 ,�,.�
��c
,
Percents a
� g
ofVFlooded,
+ o
'Pro ertiesYi+
S:�N�-mot`: t.�'�
Cost ner' "
-k[..,-- r• ,,,,Ary of
Floodetl�
� � $ -Fri .
I , Pr�opettY L
r m
uRembvetl�from
,.8_� ..�, ws '� w.-;-h+.�
�
G , fi •�4�`"
'. * h�
Irn a ance
act )0
� °� � ���
41
�, _ �:.
�' 4
4Reu se4
g.
Rankm
ws 9
?r ...,� e .
2
SB06
53,405,188
174
25
:$19;570
2
1
10
SB34t;
35;720;894
152
50
, $37;637
2
2
11
SB33
36;134;700
161
50
538, 104
2
3
6
SB04
59722;213
208
50
546741
2
4
13
SB20
$9;081,394
176
25
$51,599
2
5
3
SB25
311473.963
182
25
$63,044
2
6
9
SB14
$11455194
164
50
$69;849
2
7
1
SB09
$15,511,031
210
25
$73;862
2
8
4
SB23
313;;753;919
176
25
$78,147
2
9
t 8=w
.. SB.13.(45',,
t $2'270;125 _:t
? i1a1.0i4-,>"
k '•.".50k' 'F=thi
WS`r",$20 638i? ' "c:
21, _ m.....
10
15_:
i2SB104t41U4006'T•681s",.'4
siNtl28;,
P-3.425, :111
431.302,;,'i.
141•3>43I",;_.,xYROOr
' 12` s
: SB28 ,
fi $7?1i92+900.0.1
1*'r01 '
of 5OAReu'
,.jy$55;`3361*.V
P: %*:-
iA11 .1.2i?:-ti
7
SB30
$6,995,381
85
25
$82.299
4
13
15
SB12
$5;153,363
46
25
$112,030
4
14
14
SB18
$7,155.363
32
25
$223,605
4 •
15
12.2 Phase I &II Combined Ranking Results
A combined ranking was prepared in accordance with the recommendations of Phase I
of this SWMMP and to provide a city-wide stormwater capital improvement plan. The
combined ranking results are inclusive of all of the areas within the City and prioritize all
of the proposed improvements, by sub -basin. As stated previously, the -Phase I sub -
basins DA1-SE2, CC6-S-8, and C5-S5-3 were superseded by Phase II sub -basins
SB13, SB33, and SB20.
The revised ranking is based on the procedure described previously where the sub -
basins were ranked by the Importance Factor first and then by the Cost per Flooded
Property Removed from Flood Plain. The ranking identifies which sub -basin
improvements will provide the highest return in terms of flood protection at the lowest
cost. The final revised ranking is presented in Table 12-2.
This ranking is intended as a guidance tool to be used by the City to internally prioritize
future projects based on the findings of both Phase I and Phase II of this Stormwater
Management Master Plan. Additionally, the totals in these cost estimates are not
defined as commitments to expenditures by the City for any time period and are only
presented in order to provide the City with a magnitude of cost for the proposed
improvements.
12-2
February 2012
. gity.'of Miami
:Phase II'- Stormwater Management Master Plari:Final
Table ,12-2Phase .I8! Phase; II• Combined"Ranking,;bf•S,iib basins"
,Sufi.$
Besinj4.
wry
Rank
.�
lsby` +'
P_haser+
�� t,
�„
ub stn
�
. as er,
''
,
Phase"
a . �
,
x x l " rtp
sP1anR�1'te et1
3., r
"Construct on �
,-
Cost to
?+ ,ter
't �'
* � i
i Affected r
czop
q 4Propertres
ti E I�' -
' 4n 1.,.
4 r a ;
""r'ercentage:
$�
of -Flooded
w• ... . �
6,03roperties
i "` L'ostiper "
€; Flooded
' roperty�
s w.. e
Remo pslifro
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1-2744
15
DA1-SE-2
1
Superseded by Phase II sub -basin SB13.
14
CC6-S-8
1
Superseded by Phase II sub -basin SB33.
13
C5-S5-3
1
Superseded by Phase II sub -basin SB20.
The total of all projects presented for the top 30 ranked sub -basins within the City of
Miami totals just over $223,000,000. Over 5-years, the average yearly funding
allocation requirement would be just below $45,000,000 if all projects were -to be
constructed with the 5year_period= see Attachment Y for combined revised ranking.
12.3 .Future Project & Capital Plan Conclusion
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
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
12-3
FeOruay 2012 City of Miami
Phase II - Stormwater Management Master PlanFinal
wiU provide incremental benefits not. only to the sub -basin withi wch a project is to
reside ,:but: alSo'sProVides an ancillary: benefit to adjacent sub -basins f.- The ranking
procedures a nCIL.ProjeCts _presented.. helpto identify_areas WhereirnProve MentS will
provide the highest rate of return 'in terms of removing properties.'from the flood plain
duripg,extreme events.
A combined ranking was developed in this Phase of the SWMMP development process
which 'is' inclusive ofthe entire City ofMiami. Thitlisting of-ranked-subtasins combines
the top 15 sub -basins from both Phase I and -Phase II. The total of all projects
presented for the top 30 ranked sub -basins within the City of Miami totals just over
$223;000,000. Over 5-years, the average yearly funding allocation requirement would
be just below $45,000,000 if all projects were to be constructed with the 5-year period -
see Attachment Y for combined revised ranking.
The ranking of problem areas and improvement projects outlined in this SWMMP will
help the City provide the most flood protection benefits in a cost-effective manner,
However, because the City does not have allocated funding to address all the top
ranked problem areas in a systematic approach, the SWMMP will provide the City with
a flexible tool to implement high priority projects as funding becomes available and not
solely on the presented ranking order.
Additionally, the schematics presented in Attachment W and the cost estimates and
rankings presented in Attachments X and Y are planning level schematic designs and
costs. Their intent is to provide the City with a planning level tool to help the City
internally prioritize and desterrnine an order of magnitude cost for capital improvement
projects. The location and specific quantities for all projects should be determined
during detailed design using site specific topographic survey and geotechnical
information. Additionally, permitting requirementshould be addressed at the time of
project design and implementation due to the constantly changing permitting criteria and
requirements.
12-4