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HomeMy WebLinkAboutArticle III - Tab 3 - Site Utility Study• • • TOWER TWENTY SEVEN MAJOR USE SPECIAL PERMIT SITE UTILITY STUDY Prepared for: Landstar Development, Inc. Prepared by: Consulting Engineering and Science, Inc. September IS, 2003 • • 1. General A. Project Location and Size: The site on which the project is located has a net lot area of 56,926 square feet or 1.31 acres. The project address is 2727 Southwest 27`h Avenue with approximately 279 feet of frontage on Southwest 27'h Avenue. 138 feet of frontage on Southwest 2761 Street and 279 feet of frontage on Southwest 27'' Court on the southwest corner of Southwest 27`'' Avenue and Southwest 27'`' Street. The project is located on lots in the City of Miami designated as Lots 1 through 12 in Block 24, accordingly to the plat entitled SOUTH BAY ESTATES (PB 5, PG 54). Currently, there is a commercial building and a residential duplex existing on the site. B. The proposed project build -out will be as follows: Residential units 181 Apartments Retail 6,400 square feet Net Lot Area 56,926 square feet or 1.31 acres Gross Lot Area 84,563 square feet or 1.94 acres Construction on this site will consist of a fourteen story residential building adjacent to a four story parking structure. The retail/commercial space will be developed within the ground floor level overlooking Southwest 27''` Avenue inside the residential building. 2. Drainage A. Drainage Area After development, approximately 95% of the site will be impervious and approximately 5% of the site will be pervious. The storm water discharge will consist primarily of building roofs, driveways and landscape areas run-off. The coefficient of run-off is calculated as follows: 95% (impervious) X 0.90 plus: 5% (pervious) X 0.30 overall coefficient B. Existing Storm Drainage System: 0.855 0.015 0.870 The City of Miami presently maintains a roadway drainage system in all fronting streets. The site is presently fully developed. Runoff from the site is presently dispersed through percolation with excess runoff discharging into the existing roadway system. There appears to be no evidence of drainage problems or prolonged standing water in the streets. . • C. Proposed On -Site Storm Drainage System: The proposed storm drainage system to serve this project will be designed to fully contain on -site the storm water runoff and to meet all applicable requirements of the Miami -Dade County Department of Environmental Resources Management (DERM) and the Florida Department of Transportation (FDOT). This will be accomplished by means of deep drainage wells which will allow the stormwater runoff to be fully contained on -site. No off -site run-off will be generated from this project. .It is anticipated that two (2) drainage wells will be sufficient to handle the runoff (see Table I for drainage calculations). The stormwater will be collected through a system of catch basin inlets and transported by pipes to the well location. The wells will allow the stormwater to flow into the Biscayne Aquifer. The well will be designed to handle the stormwater runoff and tested for capacity as installed. Runoff from driving surfaces such as driveways and parking areas will be diverted through baffled pollution control structures which will capture the oils and greases prior to flowing into the well. • • • • Runoff Generations Total Net Area a. Impervious b. Pervious Table 1 Sample Drainage Calculations 1.31 Acres 95% or 1.2445 Acres 5% or 0.0655 Acres 2. Average Runoff Coefficient (.95) (_9) + (.05) (.3) = 0.87 3. Design Storm 5 years 4. Time of Concentration 10 minutes 5. Rainfall Intensity 6.10 in/hr 6. Peak Runoff (Q) = CIA (0.87) (6.10) (1.31) = 6.95 CFS Assume each 24-inch diameter drainage well has a capacity of 750 gpm per foot of head — using 2.5 feet of head; 2.5 X 750 gpm = 1,875 gpm per well 1,875 gpm = 4.18 CFS (Peak Runoff) (Flow per well) 6.95 CFS 4.18 CFS Provide 2 — 24" diameter well Detention Tank: 1.66 wells Provide 1.5 minutes of detention time of storage in tank: Volume of tank required to handle 6.95 CFS (3,1 18 gpm) for 1.5 min. = 3,118 gpm X 1.5 min = 4,677 gal/tank or 625 cubic feet Provide two (2) tanks with the following interior dimensions: 5' (width) X 5' (height) X 15' (length) — 375 cubic feet. • • 3. Water Distribution The Miami Dade Water and Sewer Department owns and operates a 24 inch water main located on Southwest 27°` Avenue, and both an 8 inch and a on Southwest 2741 Street. The water connections to serve each building will be made from the 24-inch water main. The connections will consist of fire line supply, domestic water and irrigation water. No on -site wells are planned for this project. The calculations for anticipated water volumes required for this project are shown below_ in Table 2. Table 2 Water Volumes Residential Apartments 181 units @ 200 gpd/unit 36,200 gpd Retail 6.400 SF @ 5 gpd/100 SF .320gpd Total flow demand 36,520 gpd 4. Sanitary Sewer The Miami Dade Water and Sewer Department owns and operates a gravity sewer system along both streets that have frontage on this property. It is anticipated that a single gravity connection to one of the gravity lines will be sufficient to serve this project. No pump station will be required to serve the project. Table 3 shows the anticipated sewage flow calculations as follows: Table 3 Sewage Flow Calculations Average Flow (from Table 2) .36,520.0 gpd Average Flow 25.4 gpm Peak Flow (25.4 X 3.5) 88.9 gpm 5. Solid Waste Generation Solid waste generated by this project will be collected in standardized on -site containers for refuse and recyclable waste. Regular service will be provided by either private hauling companies and/or The City of Miami Solid Waste Department. Both will transport the waste to Miami -Dade County's Disposal or Recycling facilities. The projected daily volumes of solid waste generation are shown below in Table 4. • Residential Apartments: Retail: • • Table 4 Solid Waste Generation (181 units @ 1,42 tons/unit X 2,000 lbs./tan)/365 days 1,409 lbs. (6.400 SF @ 3.08 lbs./SF}/365 days 54 lbs. Total 1,463 lbs.