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Home My WebLink AboutSDP200800056 Calculations 2008-03-18 (2)WICKHAM POND PHASE II BLOCK 2 Project Date: 3/18/2008 Project Engineer: craigk Project Title: WICKHAM POND PHASE II BLOCK 2 Project Comments: BIOFILTER ROUTING Table of Contents Table of Contents i MASTER SUMMARY * * * * * * * * * * * * * * * * * * * * ** Watershed....... Mod. Rational Grand Summary ........ 1.01 Master Network Summary ............. 1.02 DESIGN STORMS SUMMARY * * * * * * * * * * * * * * * * * ** Albemarle RDSC.. Rational Storms .................... 2.01 RAINFALL DATA * * * * * * * * * * * * * * * * * * * * * ** ALB 100yr....... 100 I -D -F Table ........................ 3.01 ALB 10yr........ 10 I -D -F Table ........................ 3.02 ALB 2yr......... 2 I -D -F Table ........................ 3.03 TC CALCULATIONS * * * * * * * * * * * * * * * * * * * ** SUBAREA 10...... PRE Tc Calcs ........................... 4.01 SUBAREA 10...... POST Tc Calcs ........................... 4.03 POND VOLUMES * * * * * * * * * * * * * * * * * * * * * ** POND 10......... Vol: Elev -Area ..................... 5.01 Table of Contents Table of Contents (continued) ii OUTLET STRUCTURES * * * * * * * * * * * * * * * * * * * ** Outlet 1........ Outlet Input Data .................. 6.01 POND ROUTING * * * * * * * * * * * * * * * * * * * * * ** POND 10......... Pond E -V -Q Table ................... 7.01 POND 10 OUT 2 Pond Routing Summary ............... 7.02 POND 10 OUT 10 Pond Routing Summary ............... 7.03 POND 10 OUT 100 Pond Routing Summary ............... 7.04 RATIONAL METHOD CALLS * * * * * * * * * * * * * * * * * ** SUBAREA 10...... 2 Mod. Rational Graph ................ 8.01 SUBAREA 10...... 10 Mod. Rational Graph ................ 8.02 SUBAREA 10...... 100 Mod. Rational Graph ................ 8.03 SUBAREA 10...... PRE C and Area ......................... 8.04 SUBAREA 10...... POST C and Area ......................... 8.05 Type.... Mod. Rational Grand Summary Page 1.01 Name.... Watershed File.... R:\404\23817-Wickham PIPE.PPW MODIFIED RATIONAL METHOD Grand Summary For All Storm Frequencies - - -- Q = CiA * Units Conversion; Where Conversion = 43560 / (12 * 3600) Area =2.410 acres Tc 3167 hrs VOLUMES Freq. Adjusted Duration I Qpeak Allowablel Inflow Storage years 'C'hrs in /hr cfs cfs I ac -ft ac -ft I--------------------- 2 .570 3333 2.9900 4.14 3.79 114 012 10 .570 3500 4.0700 5.64 5.25 163 018 100 .570 3833 5.5900 7.74 7.51 245 028 Type.... Master Network Summary Page 1.02 Name.... Watershed File.... R:\404\23817-Wickham PIPE.PPW MASTER DESIGN STORM SUMMARY Default Network Design Storm File, ID Return Event 2 10 100 Rainfall Type I -D -F Curve I -D -F Curve I -D -F Curve Albemarle RDSC IDF ID ALB 2yr ALB 10yr ALB 100yr MASTER NETWORK SUMMARY Modified Rational Method Network Node = Outfall; +Node = Diversion;) Trun= HYG Truncation: Blank =None; L =Left; R =Rt; LR= Left &Rt) Max 1.99 5000 3.38 5000 4.69 3000 3.92 3500 Return HYG Vol 7.74 Pond Storage 1.99 637.41 5000 3.38 637.49 5000 4.69 637.64 Node ID 4.14 Type Event ac -ft Trun ac -ft OUT 10 JCT 2 055 OUT 10 JCT 10 103 OUT 10 JCT 100 185 POND 10 IN POND 2 113 R POND 10 IN POND 10 162 POND 10 IN POND 100 244 R POND 10 OUT POND 2 055 082 POND 10 OUT POND 10 103 098 POND 10 OUT POND 100 185 130 SUBAREA 10 AREA 2 114 L SUBAREA 10 AREA 10 162 L SUBAREA 10 AREA 100 245 L Qpeak Qpeak Max WSEL hrs cfs ft 5000 1.99 5000 3.38 5000 4.69 3000 3.92 3500 5.44 3500 7.74 5000 1.99 637.41 5000 3.38 637.49 5000 4.69 637.64 3165 4.14 3165 5.63 3665 7.74 Type.... Rational Storms Page 2.01 Name.... Albemarle RDSC File.... R: \404 \23817- Wickham Pond Block 2 \Calc \Stm \pondpack\ Title... Project Date: 3/18/2008 Project Engineer: craigk Project Title: Watershed Project Comments: I -D -F DESIGN STORM SUMMARY Storm Queue File,ID = Albemarle RDSC Storm Tag Name = 2 File: Type, ID = : I -D -F Storm... ALB 2yr Storm Frequ. = 2 yr Storm Tag Name = 10 File: Type, ID = : I -D -F Storm... ALB 10yr Storm Frequ. = 10 yr Storm Tag Name = 100 File: Type, ID = : I -D -F Storm... ALB 100yr Storm Frequ. = 100 yr Type.... I -D -F Table Page 3.01 Name.... ALB 100yr Tag: 100 Event: 100 yr File.... R: \404 \23817- Wickham_ Pond_Block_2 \Calc \Stm \pondpack\ Storm... ALB 100yr Tag: 100 Rainfall - Intensity- Duration Curve Time, hrs Intens., in /hr 0833 1000 1167 1333 1500 1667 1833 2000 2167 2333 25C0 2667 2833 3000 3167 3333 3500 3667 3833 4000 4167 4333 4500 4667 4833 5000 5167 5333 5500 5667 5833 6667 7500 8333 9167 1.0000 9.4900 9.1300 8.8000 8.5000 8.2100 7.9500 7.7000 7.4600 7.2400 7.0300 6.8400 6.6500 6.4800 6.3100 6.1500 6.0000 5.8600 5.7200 5.5900 5.4600 5.3400 5.2300 5.1200 5.0200 4.9200 4.8200 4.7300 4.6400 4.5500 4.4700 4.3900 4.0300 3.7200 3.4600 3.2300 3.0300 Type.... I -D -F Table Page 3.02 Name.... ALB 10yr Tag: 10 Event: 10 yr File.... R: \404 \23817- Wickham Pond Block 2 \Calc \Stm \pondpack \' Storm... ALB 10yr Tag: 10 Rainfall - Intensity- Duration Curve Time, hrs Intens., in /hr 0833 6.8100 1000 6.5300 1167 6.2800 1333 6.0500 1500 5.8300 1667 5.6200 1833 5.4400 2000 5.2600 2167 5.0900 2333 4.9400 2500 4.7900 2667 4.6500 2833 4.5200 3000 4.4000 3167 4.2800 3333 4.1700 3500 4.0700 3667 3.9700 3833 3.8700 4000 3.7800 4167 3.7000 4333 3.6100 4500 3.5300 4667 3.4600 4833 3.3900 5000 3.3200 5167 3.2500 5333 3.1900 5500 3.1200 5667 3.0600 5833 3.0100 6667 2.7500 7500 2.5400 8333 2.3500 9167 2.1900 1.0000 2.0500 Type.... I -D -F Table Page 3.03 Name.... ALB 2yr Tag: 2 Event: 2 yr File.... R:\404\23817-Wickham Storm... ALB 2yr Tag: 2 Rainfall - Intensity- Duration Curve Time, hrs Intens., in /hr 0833 1000 1167 1333 1500 1667 1833 2000 2167 2333 2500 2667 2833 3000 3167 3333 3500 3667 3833 4000 4167 4333 4500 4667 4833 5000 5167 5333 5500 5667 5833 6667 7500 8333 9167 1 .0000 5.1700 4.9300 4.7100 4.5100 4.3300 4.1600 4.0000 3.8500 3.7200 3.5900 3.4700 3.3600 3.2600 3.1600 3.0700 2.9900 2.9000 2.8300 2.7500 2.6800 2.6200 2.5500 2.4900 2.4400 2.3800 2.3300 2.2800 2.2300 2.1900 2.1400 2.1000 1.9100 1.7500 1.6200 1.5000 1.4000 Type.... Tc Calcs Page 4.01 Name.... SUBAREA 10 Tag: PRE File.... R:\404\23817-Wickham PIPE.PPW TIME OF CONCENTRATION CALCULATOR Segment #1: Tc: User Defined Segment #1 Time: .2667 hrs Total Tc: .2667 hrs Type.... Tc Calcs Page 4.02 Name.... SUBAREA 10 Tag: PRE File.... R:\404\23817-Wickham PIPE.PPW Tc Equations used... User Defined _______________________ _______________________________ Tc = Value entered by user Where: Tc = Time of concentration Type.... Tc Calcs Page 4.03 Name.... SUBAREA 10 Tag: POST File.... R: \404 \23817- Wickham Pond Block 2 \Calc \Stm \pondpack \OVERSIZED PIPE.PPW — TIME OF CONCENTRATION CALCULATOR Segment #1: Tc: User Defined Segment #1 Time: .3167 hrs Total Tc: .3167 hrs Type.... Tc Calcs Page 4.04 Name.... SUBAREA 10 Tag: POST File.... R:\404\23817-Wickham PIPE.PPW Tc Equations used... User Defined _____ ---------- ________ _____________________---------- Tc = Value entered by user Where: Tc = Time of concentration Type.... Vol: Elev -Area Name.... POND 10 Page 5.01 File.... R:\404\23817-Wickham PIPE.PPW Elevation Planimeter Area Al +A2 +sgr(Al *A2)Volume Volume Sum ft)sq.in) (acres)acres)ac -ft)ac -ft) 637.00 1917 0000 000 000 637.50 2065 5971 100 100 638.00 2363 6638 111 210 POND VOLUME EQUATIONS Incremental volume computed by the Conic Method for Reservoir Volumes. Volume = (1/3) * (EL2 -ELl) * (Areal + Area2 + sq.rt.(Areal *Area2)) where: EL1, EL2 = Lower and upper elevations of the increment Areal,Area2 = Areas computed for EL1, EL2, respectively Volume = Incremental volume between ELl and EL2 Type.... Outlet Input Data Name.... Outlet 1 Page 6.01 File.... R:\ 404\ 23817 - Wickham _Pond_Block_2 \Calc \Stm \pondpack \OVERSIZED PIPE.PPW REQUESTED POND WS ELEVATIONS: Min. Elev.= 637.00 ft Increment = .50 ft Max. Elev.= 638.00 ft OUTLET CONNECTIVITY Forward Flow Only (UpStream to DnStream) Reverse Flow Only (DnStream to UpStream) Forward and Reverse Both Allowed Structure No. Outfall El, ft E2, ft Inlet Box Rl - - -> Cl 637.300 638.000 Culvert - Circular Cl - - -> TW 633.000 638.000 TW SETUP, DS Channel Type.... Outlet Input Data Name.... Outlet 1 Page 6.02 File.... R: \404 \23817- Wickham Pond Block 2 \Calc \Stm \pondpack \OVERSIZED PIPE.PPW — — — OUTLET STRUCTURE INPUT DATA Structure ID R1 Structure Type Inlet Box of Openings 1 Invert Elev.637.30 ft Orifice Area 9.0000 sq.ft Orifice Coeff.600 Weir Length 12.00 ft Weir Coeff.3.300 K, Reverse 1.000 Mannings n 0000 Kev,Charged Riser 000 Weir Submergence No Type.... Outlet Input Data Name.... Outlet 1 Page 6.03 File.... R:\404\23817-Wickham PIPE.PPW OUTLET STRUCTURE INPUT DATA Structure ID Cl Equation form = Structure Type Culvert - Circular No. Barrels 1 2.0000 Barrel Diameter 1.0000 ft Upstream Invert 633.00 ft Dnstream Invert 631.50 ft Horiz. Length 75.00 ft Barrel Length 75.02 ft Barrel Slope 02000 ft /ft OUTLET CONTROL DATA... Mannings n = .0130 Ke = .5000 Kb = .031274 Kr = .5000 HW Convergence = .001 INLET CONTROL DATA... Equation form =1 Inlet Control K =0098 Inlet Control M =2.0000 Inlet Control c =03980 Inlet Control Y =6700 T1 ratio (HW /D) _000 T2 ratio (HW /D) =1.297 Slope Factor =500 forward entrance loss) per ft of full flow) reverse entrance loss) ft Use unsubmerged inlet control Form 1 equ. below Tl elev. Use submerged inlet control Form 1 equ. above T2 elev. In transition zone between unsubmerged and submerged inlet control, interpolate between flows at T1 & T2... At T1 Elev = 633.00 ft - - -> Flow = 2.75 cfs At T2 Elev = 634.30 ft - - -> Flow = 3.14 cfs Structure ID = TW Structure Type = TW SETUP, DS Channel FREE OUTFALL CONDITIONS SPECIFIED CONVERGENCE TOLERANCES... Maximum Iterations= 40 Min. TW tolerance = .01 ft Max.TW tolerance =01 ft Min.HW tolerance =01 ft Max.HW tolerance =01 ft Min.Q tolerance =00 cfs Max.Q tolerance =00 cfs Type.... Pond E -V -Q Table Page 7.01 Name.... POND 10 File.... R:\ 404 \23817 Wickham_Pond_Block_2 \Calc \Stm \pondpack \OVERSIZED PIPE.PPW LEVEL POOL ROUTING DATA HYG Dir = R:\ 404\ 23817 Wickham_Pond_Block_2 \Calc \Stm \pondpack\ Inflow HYG file = work_pad.hyg - POND 10 IN 2 Outflow HYG file = work pad.hyg - POND 10 OUT 2 Pond Node Data = POND 10 Pond Volume Data = POND 10 Pond Outlet Data = Outlet 1 No Infiltration INITIAL CONDITIONS Starting WS Elev =637.00 ft Starting Volume =000 ac -ft Starting Outflow =00 cfs Starting Infiltr. _00 cfs Starting Total Qout=00 cfs Time Increment =0500 hrs Elevation Outflow Storage Area Infilt.Q Total 2S /t + 0 ft cfs ac -ft acres cfs cfs cfs 637.00 00 000 1917 00 00 00 637.30 00 059 2005 00 00 28.47 637.50 3.54 100 2065 00 3.54 51.71 638.00 7.54 210 2363 00 7.54 109.25 Type.... Pond Routing Summary Page 7.02 Name.... POND 10 OUT Tag: 2 Event: 2 yr File.... R:\404\23817-Wickham PIPE.PPW Storm... ALB 2yr Tag: 2 LEVEL POOL ROUTING SUMMARY HYG Dir = R: \404 \23817- Wickham Pond Block 2 \Calc \Stm \pondpack\ Inflow HYG file = work_pad.hyg - POND 10 IN 2 Outflow HYG file = work pad.hyg - POND 10 OUT 2 Pond Node Data = POND 10 Pond Volume Data = POND 10 Pond Outlet Data = Outlet 1 No Infiltration IiMNIIiG1iK11)yllr1I Starting WS Elev =637.00 ft Starting Volume =000 ac -ft Starting Outflow =00 cfs Starting Infiltr. _00 cfs Starting Total Qout=00 cfs Time Increment =0500 hrs INFLOW /OUTFLOW HYDROGRAPH SUMMARY Peak Inflow 3.92 cfs at .3000 hrs Peak Outflow 1.99 cfs at .5000 hrs Peak Elevation 637.41 ft Peak Storage =082 ac -ft MASS BALANCE (ac -ft) Initial Vol = .000 HYG Vol IN = .113 Infiltration = .000 HYG Vol OUT = .055 Retained Vol = .059 Unrouted Vol = -.000 ac -ft (.004r of Inflow Volume) WARNING: Inflow hydrograph truncated on right side. Type.... Pond Routing Summary Page 7.03 Name.... POND 10 OUT Tag: 10 Evert: 10 yr File.... R:\404\23817-Wickham PIPE.PPW Storm... ALB 10yr Tag: 10 LEVEL POOL ROUTING SUMMARY HYG Dir = R: \404 \23817- Wickham Pond Block 2 \Cale \Stm \pondpack\ Inflow HYG file = work pad.hyg - POND 10 IN 10 Outflow HYG file = work pad.hyg - POND 10 OUT 10 Pond Node Data = POND 10 Pond Volume Data = POND 10 Pond Outlet Data = Outlet 1 No Infiltration INITIAL CONDITIONS Starting WS Elev =637.00 ft Starting Volume =000 ac -ft Starting Outflow =00 cfs Starting Infiltr. _00 cfs Starting Total Qout=00 cfs Time Increment =0500 hrs INFLOW /OUTFLOW HYDROGRAPH SUMMARY Peak Inflow 5.44 cfs at .3500 hrs Peak Outflow 3.38 cfs at .5000 hrs Peak Elevation 637.49 ft Peak Storage =098 ac -ft MASS BALANCE (ac -ft) Initial Vol = .000 HYG Vol IN = .162 Infiltration = .000 HYG Vol OUT = .103 Retained Vol = .059 Unrouted Vol = -.000 ac -ft (.0009 of Inflow Volume) Type....Pond Routing Summary Page 7.04 Name....POND 10 OUT Tag: 100 Event: 100 yr File....R:\404\23817-Wickham 00 cfs PIPE.PPW Infiltr. _00 cfs Storm...ALB 100yr Tag: 100 cfs LEVEL POOL ROUTING SUMMARY HYG Dir = R: \404 \23817- Wickham Pond Block 2 \Calc \Stm \pondpack\ Inflow HYG file = work pad.hyg - POND 10 IN 100 Outflow HYG file = work pad.hyg - POND 10 OUT 100 Pond Node Data = POND 10 Pond Volume Data = POND 10 Pond Outlet Data = Outlet 1 No Infiltration INITIAL CONDITIONS Starting WS Elev =637.00 ft Starting Volume =000 ac -ft Starting Outflow =00 cfs Starting Infiltr. _00 cfs Starting Total Qout=00 cfs Time Increment =0500 hrs INFLOW /OUTFLOW HYDROGRP.PH SUMMARY Peak Inflow 7.74 cfs at .3500 hrs Peak Outflow 4.69 cfs at .5000 hrs Peak Elevation 637.64 ft Peak Storage -130 ac -ft MASS BALANCE (ac -ft) Initial Vol = .000 HYG Vol IN = .244 Infiltration = .000 HYG Vol OUT = .185 Retained Vol = .059 Unrouted Vol = -.000 ac -ft (.002% of Inflow Volume) WARNING: Inflow hydrograph truncated on right side. Type.... Mod. Rational Graph Page 8.01 Name.... SUBAREA 10 Tag: 2 Event: 2 yr File.... R:\404\23817-Wickham PIPE.PPW Storm... ALB 2yr Tag: 2 MODIFIED RATIONAL METHOD Graphical Summary for Maximum Required Storage - - -- Method I Q = CiA * Units Conversion; Where Conversion = 43560 / (12 * 3600) RETURN FREQUENCY: 2 yr Allowable Outflow: 3.79 cfs C' Adjustment: 1.000 Required Storage: .012 ac -ft Peak Inflow: 4.14 cfs HYG File: 2 Q I Approx. I I I I I - I •I I I I I I • I I I 1 x x Td = .3333 hrs Duration for Max. Storage - - - - - -/ I I Tc= .3167 hrs I = 3.0700 in /hr Q = 4.25 cfs I Required Storage 012 ac -ft I I x x x x x xlx x x x x x x x x x x I Return Freq: 2 yr C adj.factor:1.000 Area = 2.410 acres Weighted C = .570 Adjusted C = .570 Td= .3333 hrs I = 2.9900 in /hr Q = 4.14 cfs x 1 o Q = 3.79 cfs 1 x o Ix (Allow.Outflow) x o x o NOT TO SCALE 1 x xo ----- - - - - -- 1 0 1 x 1 ------------ 3599 hrs T Type.... Mod. Rational Graph Page 8.02 Name.... SUBAREA 10 Tag: 10 Event: 10 yr File.... R:\ 404 \23817- Wickham _Pond_Block_2 \Calc \Stm \pondpack \OVERSIZED PIPE.PPW Storm... ALB 10yr Tag: 10 MODIFIED RATIONAL METHOD Graphical Summary for Maximum Required Storage - - -- Method I Q = CiA * Units Conversion; Where Conversion = 43560 / (12 * 3600) RETURN FREQUENCY: 10 yr I Allowable Outflow: 5.25 cfs C' Adjustment: 1.000 1 Required Storage: .018 ac -ft Peak Inflow: 5.64 cfs HYG File: 10 Q I Td = .3500 hrs I Return Freq: 10 yr Approx. Duration for Max. Storage - - - - - -/ C adj.factor:1.000 I I I I Tc= .3167 hrs 1 I = 4.2800 in /hr 1 Area = 2.410 acres Q = 5.93 cfs 1 Weighted C = .570 I• Adjusted C = .570 I I Required Storage 1 018 ac -ft Td= .3500 hrs I = 4.0700 in /hr x x x x x x x 1 x x x x x x x x x x x Q= 5.64 cfs I I x x o Q = 5.25 cfs x o Ix (Ailow.0utflow) 1 x 0 1 x o NOT TO SCALE 1 x 1 x o ____________ o x I ------------ 3717 hrs T Type.... Mod. Rational Graph Page 8.03 Name.... SUBAREA 10 Tag: 100 Event: 100 yr File.... R:\ 404\ 23817 Wickham_Pond_Block_2 \Cale \Stm \pondpack \OVERSIZED PIPE.PPW Storm... ALB 100yr Tag: 100 MODIFIED RATIONAL METHOD Graphical Summary for Maximum Required Storage - - -- Method I Q = CiA * Units Conversion; Where Conversion = 43560 / (12 * 3600) RETURN FREQUENCY: 100 yr I Allowable Outflow: 7.51 cfs C' Adjustment: 1.000 1 Required Storage: .028 ac -ft Peak Inflow: 7.74 cfs HYG File: 100 Q I Td = .3833 hrs I Return Freq: 100 yr Approx. Duration for Max. Storage - - - - - -/ C adj.factor:1.000 Tc= .3167 hrs I = 6.1500 in /hr 1 Q = 8.52 cfs I• I I I Required Storage I 028 ac -ft I I I x x x x x x xIx x x x x x x x x x x I x Area = 2.410 acres Weighted C = .570 Adjusted C = .570 Td= .3833 hrs I = 5.5900 in /hr Q = 7.74 cfs X o Q = 7.51 cfs x o Ix (Allow.Outflow) x o X o NOT TO SCALE x x o ------ - -___= o x I ------------ 3929 hrs T Type.... C and Area Name.... SUBAREA 10 Tag: PRE Page 8.04 File.... R: \404 \23817- Wickham Pond Block 2 \Cale \Stm \pondpack \OVERSIZED PIPE.PPW — — — RATIONAL C COEFFICIENT DATA Area C x Area Soil /Surface Description C acres acres 3500 3.200 1.120 WEIGHTED C & TOTAL AREA - - -> .3500 3.200 1.120 Type.... C and Area Page 8.05 Name.... SUBAREA 10 Tag: POST File.... R: \404 \23817- Wickham Pond Block 2 \Calc \Stm \pondpack \OVERSIZED PIPE.PPW — — — RATIONAL C COEFFICIENT DATA Area C x Area Soil /Surface Description C acres acres 5700 2.410 1.374 WEIGHTED C & TOTAL AREA - - -> .5700 2.410 1.374 Appendix A Index of Starting Page Numbers for ID Names A - - - -- ALB 100yr 100... 3.01 ALB 10yr 10... 3.02 ALB 2yr 2... 3.03 Albemarle RDSC... 2.01 0 - - - -- Outlet 1... 6.01 P - - - -- POND 10... 5.01, 7.01, 7.02, 7.03, 7.04, 8.01, 8.02, 8.03, 4.01, 8.04, 4.03, 8.05 A -1 W ----- Watershed ... 1.01, 1.02 P14AS 2 VJ ice -00A N10 8L- 0e-K Z Modified Simple Method Worksheets Divide the Site into Drainage Areas — Worksheet I Calculate the area in acres for each drainage area, and label each drainage area on the plan. It will be necessary to fill out the following series of worksheets for each drainage area. Drainage Area 1:3. 2 acres (on- site); ---acres (off - site);3. 7 -0 total acres Drainage Area 2:acres (on- site);acres (off - site);total acres Drainage Area 3:acres (on- site);acres (off - site);total acres Drainage Area 4:acres (on- site);acres (off - site);total acres Drainage Area S:acres (on- site);acres (off - site);total acres Drainage Area 6:acres (on- site);acres (off - site);total acres Drainage Area 7:acres (on- site);acres (off - site);total acres Total (On -site) Area = 3.2d acres r 05 February 2003 WR-8 Calculate Pre - Development Impervious Cover (I pre) - Worksheet 2 Calculate I(pre) using actual site information for each drainage area (on -site acres only) as identified in Worksheet 1. If the project is phased, include only the active phase(s). DRAINAGE AREA # i ON -SITE AREA = 5.2o ACRES (on -site drainage area size) Roads: length (ft) x width (ft) for all roads _ Driveways: average length (ft) x average width (ft) x number of driveways = Parking Lots: square footage _ Gravel Areas: square footage x 0.70 _ Structures (including houses): sum of actual square footage for all structures, OR average house square footage x number of houses _ Actively - grazed pasture (livestock present), Yards & areas of cultivated turf actual square footage of areas x 0.08, OR average yard area x number of yards x 0.08. _ Active crop land: square footage x 0.25 _ Other Impervious Areas _ square feet square feet square feet square feet square feet square feet square feet square feet Total Equivalent Impervious Area = 0 square feet (sum of all the above values) I(pre) = Total Equivalent Impervious Cover (sft) x 100 = % 43560 sq it per acre /on -site drainage area (acs.) DRAINAGE AREA # ON -SITE AREA = ACRES (on -site drainage area size) Roads: length (ft) x width (ft) for all roads . =square feet Driveways: average length (ft) x average width (ft) x number of driveways =square feet Parking Lots: square footage =square feet Gravel Areas: square footage x 0.70 =square feet Structures (including houses): sum of actual square footage for all structures, OR average house square footage x number of houses =square fleet Actively - grazed pasture (livestock present), Yards & areas of cultivated turf: actual square footage of areas x 0.08, OR average yard area x number of yards x 0.08 =square feet Active crop land: square footage x 0.25 =square feet Other Impervious Areas =square feet Total Equivalent Impervious Area = square feet (sum of all the above values) I(pre) = Total Equivalent Impervious Cover (5,q ft) x 100 = % 43560 sq ft per acre /on -site drainage area (acs.) 05 February 2003 WR -8 Calculate Pre- Development Phosphorus Load (Lpre) — Worksheet 3 Use the following table to calculate L(pre) based on the water resources area in which the project is located. Development Area, where I(pre) is less than 41xAorequalto20% Development Area, where I(pre) is greater 6.14 x [0.05 + (0.009)(Ipre)) x A than 20% Water Supply Protection Area, no existing 0.15 x A impervious cover (do not count existing equivalent impervious cover from pasture or crop land) Water Supply Protection Area, site with 3.07 x [0.05 + (0.009XIpre)] x A existing impervious cover Other Rural Land, no existing impervious 0.21 x A cover (do not count existing equivalent impervious cover from pasture or crop land) Other Rural Land, site with existing 3.51 x [0.05 + (0.009)(Ipre)J x A impervious cover L(pre) = Pre- Development Phosphorus Load (pounds/year) I (pre) = Pre - Development Equivalent Impervious Cover expressed in whole numbers from Worksheet 2) A = On -Site Drainage Area (acres) DRAINAGE AREA # ON -SITE AREA = 3 -20 ACRES (on -site drainage area size) L (pre) = pounds per year (annual loading) 05 February 2003 WR -8 Calculate Post - Development Ultimate Impervious Cover (I post) - Worksheet 4 Use the following worksheet to calculate I(post) using assumed figures for build -out of the project, including roads, houses, driveways, yards, etc. DRAINAGE AREA # l ON -SITE AREA = 1, ACRES (on -site drainage area size) Roads: length (ft) x width (ft) for all roads . = square feet Driveways: average length (ft) x average width (ft) x number of driveways = square feet Parking Lots: square footage = square feet Gravel Areas: square footage x 0.70 = square feet Structures (including houses): sum of actual square footage for all structures, OR average house square footage x number of houses = square feet Actively - grazed pasture (livestock present), Yards & areas of cultivated turf. actual square footage of areas x 0.08, OR average yard area x number of yards x 0.08 = square feet Active crop land: square footage x 0.25 = square feet Other Impervious Areas = 17, ME square feet Total Equivalent Impervious Area = t& square feet (sum of all the above values) I(post) = Total Equivalent Impervious Cover (§Q ft) x 100 = 17• g % 43560 sq ft per acre/on -site drainage area (acs.) DRAINAGE AREA # ON -SITE AREA = ACRES (on -site drainage area size) Roads: length (ft) x width (ft) for all roads _ Driveways: average length (ft) x average width (ft) x number of driveways = Parking Lots: square footage _ Gravel Areas: square footage x 0.70 = Structures (including houses): sum of actual square footage for all structures, OR average house square footage x number of houses = Actively - grazed pasture (livestock present), Yards & areas of cultivated turf: actual square footage of areas x 0.08, OR average yard area x number of yards x 0.08. _ Active crop land: square footage x 0.25 _ Other Impervious Areas _ square feet square feet square feet square feet square feet square feet square feet square feet Total Equivalent Impervious Area = square feet (sum of all the above values) I(post) = Total Equivalent Impervious Cover (Ig ft) x 100 = % 43560 sq ft per acre /on -site drainage area (acs.) 05 February 2003 UM Calculate Post - Development Phosphorus Load (L post) — Worksheet S L(post) = Post- Development Phosphorus Load (pounds/year) I (post) = Post- Development Equivalent Impervious Cover expressed in whole numbers from Worksheet 4) A = On -Site Drainage Area (acres) DRAINAGE AREA # l ON -SITE AREA = 1.74 ACRES (on -site drainage area size) L (post) = Z-- 2S pounds per year (annual loading) DRAINAGE AREA # ON -SITE AREA = ACRES (on -site drainage area size) L (post) = pounds per year (annual loading) DRAINAGE AREA # ON -SITE AREA = ACRES (on -site drainage area size) L (post) = pounds per year (annual loading) O5 February 2003 WR -8 Use the following table to calculate L(post) based on the water resources area in which the project is located. Calculate Pollutant Removal Requirement — Worksheet 6 RR = (Pollutant) Removal Requirement = L post — ( L pre x f ) (pounds per year) Where "f' is a factor applied to the Removal Requirement based upon the Conditions described below. RR = Overall BNT Pollutant Removal Efficiency = ( RR x 100 ) / L post (percent) Condition 1 — "No Existing Impervious Cover"; f= 1.0 This condition does not include equivalent impervious cover from pasture /crop land. It includes "new development" in all water resources areas and "adding impervious cover to existing sites" when existing impervious cover is within: Development Area and is less than or equal to 20% Water Supply Protection Area and is 0% Other Rural Land and is less than or equal to I% Condition 2 — "Adding Impervious Cover To Sites With Existing Impervious Cover" in the Development Areas ; f = 0.90 This condition includes "adding impervious cover to existing sites" when existing impervious cover is greater than 20% or is designated as "infill and redevelopment ". Condition 3 — "Adding Impervious Cover To Sites With Existing Impervious Cover" in the Water Supply Protection Area or Other Rural Land ; f = 0.85 This condition includes "adding impervious cover to existing sites" when existing impervious cover is within: Water Supply Protection Area and is greater than 0% Other Rural Land and is greater than I% Designated as "infill and redevelopment" DRAINAGE AREA # L post = 2 ,2- S I Condition: dr 1 L pre = 4, 5- f RR = 0 0 2 O 3 RR = _ % O5 February 2003 WR-8