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HomeMy WebLinkAboutStormwater Management CalculationsStormwater Management -Calculations for Apostle Faith Church of Deliverance St. Lucie',County, Florida March, 2000 Prepared by; Stephen Cooper, P.E. & Associates, Inc. 209 NE Sagamore Terrace " Port St. Lucie, Florida 34983 (5 879-7779 fax (561) 878-5151 E gi P ect #00100 Ste Cooper, P.E. #46557 i 8'1'EVhEN CUU.?EE,, ?.h. & fi`.r71J1.11j'ddS Surface Water Management Calculations Project,ID: Apostle Faith Church Date: 3/7/00 I. Proposed Acreages 1. Lakes = 0 2. Roofs = .16 3. Other Paving = .32 4. Green Area. _ .67 Tot. Project Area (ac) = 1.15 -II. Water Quality Calculations 1. Compute 1st inch of runoff over total area: 1 in. X Total Area/12 = 9.583333E-02 2. Compute 2.5 in. x Percent Impervious: Site Area for WQ = Total -Roofs -Lakes = .99 Impervious Area for WQ = Site -Pervious = .32 Percentage of Imperviousness for WQ = .3232323 2.5 in. x Percent Imp. x (Total-Lakes)/12.= 7.744108E-02 3. Required Water Quality Wet. Detention Vol (ac-ft) = 9.583333E-02 4. Required Dry Detention Volume equals .75 times Required Wet Detention Volume (ac-ft.) _ .071875 5. Required Retention Volume equals .5 times Required Wet. Detention Volume (ac-ft) = 4.791667E-02 III. Soil Storage Calculations 1. Compute Pervious Area for Soil Storage Total Pervious Area (acres) _ .67 2. Compute Depth to Water Table Depth to WSWT (ft) = Ave Site - WSWT = 4 3. Initial Soil Storage Extraction (in) = 8.18 4. Composite Site Soil Moisture Storage = Percent Pervious times Compacted Soil Moisture Storage (in) = 4.76574 iv. Water Quantity Calculations 1. Parking Design Storm: 5-year,1-hour (in) = 3.2 ' - Lowest Proposed Parking Lot Grate (ft-NGVD) = 20.5 Runoff from 5-year,1-hour storm (ac-ft) = CAR/12 C = .4921739 A = 1.15 R = 3.2 Q (5yr,lhr) = .1509333 2. Road Design Storm: 24 Rainfall Amount (in) = 6 Minimum Road Crown Elevation (ft-NGVD) = 20.5 SCS Runoff Formula Q (in) = (P-0.2S)-2/(P+0.8S) f' Q (ac-ft) = Q (in) x Total Project Area/12 = Road Design Storm Runoff (ac-ft) = .2487563 3. Project Design Storm: 24hr Rainfall (in) = 7.5 72hr Rainfall (in) = 10.1925 Minimum Project Perimeter Elevation (ft-NGVD) = 21 Using SCS as in 2.; Design Storm Runoff (ac-ft) = .5841356 4. Floor Design Storm: 100yr,24hr Rainfall (in) = 9.2 100yr, 72hr 'Rainfall. (in) = 12.5028 Minimum First Floor Elevation (ft-NGVD) = 22.4 Using SCS as in 2.; 100yr,72hr Runoff (ac-ft) = .7835321 S.Cooper i f Staga -- !to�-ag� Co�apaAiat:L Em ' .08 ac .07 ac .26 ac .58 ac QStage Dry Ret Dry Ret Parking Site Total -Feet Storage Storage Storage Storage Storage wGVD ac-ft ac-ft ac-ft. ac-ft ac-ft ** * 21. 21.6 22.4 18 *** 18 ***** 20.5 ***** 20.6 --------------------------- 10.00 0.00 - 0.00 0.00 0.00 0.00 18.10 0.01 0.00 0.00 0.00 0.01 i8.20 0.02 0.00. 0..00 0.00 0.02 18:30 0.02 .0.00 0.00 0.00 0.02 18.40 0.03 0.00 0.00 0.00 0.03 18.50 0.04 -0.00 0.00 0.00., 0.04 18.60 0.05 0.00 0.00 0.00 0.05 1f 0.06 0.01 0.00 0.00 0.07 18.80 0.06 0.01 0.00 0.00• 0.07 18.90. 0.07. 0.0.1 0.00 0'.00 0.08 19.00 0.08, 0.01. 0.00 0.00 0.09 19.10 0.09 0.01 0.00 •0.00 0.10 19.20. 0.10 0.02 0.00 0.00 0.12 19.30 0.10 0.02 0.00 0.00 0.12, ` 19.40 '0.11 0.02 0.00 0.00 0.13 19.50 0.12 0.03 '0.00 0.00 0'.15 19.60 0..'13 0.03 0.00 0.00 0`.16 19.70 0.14 0.03 0.00 0.00 0.17 19.80 G.14 0.04 0.00 0.00 0.18 19.90 0.15 0.04 0.00 0.00 0.19 '20:00 0.16 0.05 0.00 0.00 0.21 20.10 0.17 0.05 0.00 0.00 0.22 20.20 0.18 0.06 0.00 0.00 0.24 20.30 0.18 0.06 0.00 0.00 0.24 kO YIZ 20.,40 0.19 0.07 0.00 0.00 0.26 20.50 0.20 0..07 0.00 0.00 0.27 20.60 0.21 0.08 0.00 0.00 0.29 20'.70 0.22 0.09 0.00 0.00 0.31 20.80 0.22' 0.09 0.01 0.01 0.33 20.90 0.23 0.10 -0.02 0.01 0.36 21.00 0.24 0.11 0.03 0.03 0.41 21.10 0.25 0.11 0.04 0.04 0.44 21.20 0.26 0.12 0.06 0.06 0.50 21.30. 0.26 0.13 0.08 0.08 0.55 21.40 0.27 0.13• 0.10 0.10 0.60 AS L(r _ 21.50 0.28 0.14 0.12 0.13 0.67 tX-s1-). 21.60 0.29 0.15 0.14 0.16 0.74 . 21.70 0-. 30 0.15 0.17' 0.19 0.81 too v2 21.80 0.30 0.16 0.20 0.23 0.89 S lbca4, 21.90 0.31 0.17 0.22 0.27 0.97 22.60 0.32 0.18 0.25 0.32. 1.07 22.10 0.33 0.18 0.27 0.36 1.14 22:20 0.34 0.19 0.30 0.41 1.24 •22.30 0.34 0.20 0.33 0.47 1.34 22; 4'0 . 0.35 0.20 0.35 0.52 1.42 22.50 0.36 0.21 0.38 0.58 1.53