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HomeMy WebLinkAboutWPO202100071 Stormwater Management Maintenance Agree. 2022-10-14Dewberry, PREPARED FOR Albemarle County Service Authority 168 Spotnap Road Charlottesville, VA 22911 PREPARED BY Dewberry 4805 Lake Brook Drive, Suite 200 Glen Allen, VA 23060 Phone: 804.205.3331 Contact: Hannah Gill AVON MAINTENANCE YARD ALBEMARLE COUNTY. VA TABLE OF CONTENTS A. STORMWATER MANAGEMENT 3 t. Project Description 3 ................................................................................................................................................................................... 2. Water Quality 3 ................................................................................................................................................................................... 3. Water Quantity 4 APPENDIX A — VRRM APPENDIX B — BMP ROUTINGS APPENDIX C — WATER QUANTITY CALCULATIONS APPENDIX D — SEDIMENT BASIN ROUTING Dewberry STORMWATER MANAGEMENT 2 AVON MAINTENANCE YARD ALBEMARLE COUNTY. VA STORMWATER MANAGEMENT Project Description The Avon Maintenance Yard project in Albemarle County, VA includes the development of a maintenance fleet garage, an access road from Avon Street Ext. to Founders Place, a fuel station, vehicle wash area and a detention pond. The site is located between Avon Street Ext. and Founders Place. It's south of Mill Creek Drive. Figure 1 below shows the location of the project. The total disturbance for this project is approximately 7.31 ac and a total of 3.04 ac of impervious will be added. The site drains to 3 outfalls — 2 outfalls are along Avon Street Extension (AO 2) and Founder's Place (AO 3). The main outfall (AO 1) is an existing channel on the northern side of the site which combines with AO 3 approximately 500 feet downstream of AO 1. The project ultimately outfalls to Moores Creek and is located in the Moores Creek VA HUC 6 watershed. The project adheres to the Virginia Department of Environmental Quality IIB stormwater management criteria to meet water quality and quantity requirements Figure 1 — Avon Maintenance Yard Site Area Dewberry STORMWATER MANAGEMENT $ AVON MAINTENANCE YARD ALBEMARLE COUNTY. VA Water Quality Water quality was analyzed using the new development criteria for the Virginia Runoff Reduction Method. This analysis determined the required phosphorous removal for the Avon Maintenance Yard project is 5.99 lb/yr. This removal will be met through the purchase of nutrient credits. The VRRM Spreadsheet is included in Appendix A. Existing and proposed land use maps are included in the ACSA Avon Maintenance Yard site plan, sheets C-602 through C-605. Water Quantity Water quantity for this project was analyzed for the 1-year and 10-year storm events at the project outfalls: upstream of existing culverts on the northern side of the project (AO 1 and AO 3) and the proposed stormsewer system installed with the Timmons Group Avon Street Project (AO 2). To meet the water quantity requirements at AO 1 a detention pond is proposed. To meet quantity requirements at A03, a detention weir wall is proposed at the south corner of the site. The routings and calculations for the proposed detention facilities are included in Appendix B. The proposed detention pond is designed with a SWM-1 structure. The proposed structure has an orifice at the bottom of the pond which controls the 1-year discharge. The 10-year and 100-year discharges are controlled by a weir notch and top of structure at 526.90ft. There is 2.05tt of freeboard provided for the 100-year storm. The structure detail is included in the site plan on sheet C-609. The detention weir wall for AO 3 detail is included in the site plan on sheet C- 506. The weir wall has an orifice at the bottom of the proposed ditch which controls the 1-year discharge. The 10-year and 100-year discharges are controlled by the orifices and top of the weir wall at 531.90ft. Channel Protection Channel protection is met on this project through the energy balance analysis. The post developed 1-year discharge is less than the allowable discharge calculated by the energy balance equation for AO 1 and AO 3. For the energy balance analysis, the offsite area (Existing Offsite Discharge) that drains and is detained in the pond is included in the allowable discharge. This offsite includes the existing water tank area that is not being disturbed during this project. Energy Balance calculations are included in Appendix C. Table 1 — Energy Balance Discharges Outfall Existing 1- year Discharge (cfs) Existing Offsite 1- year Discharge (cfs) Allowable Discharge (cfs) Proposed 1- year Discharge (cfs) AO 0.69 2.00 2.11 1.57 AO 3 0.93 2.06 2.22 2.18 Flood Protection Flood protection has been met on this project because the proposed 10-year discharge is less then the existing 10- year discharge. Flood protection calculations are included in Appendix C. Table 2 —10-Year Discharges Outfall Existing 10- year Discharge (cfs) Proposed 10- year Discharge (cfs) AO 1 9.68 5.61 AO 3 10.83 6.57 Dewberry STORMWATER MANAGEMENT 4 APPENDIX A: VRRM DEQ Virginia RunoffRemdon Method New Developments plionce Spmodshen-Version3.0 C 2011 BMP Standards and Specificat♦ W13 Draft BMP Standards and Specifications Project Name: Avon Site deM Irout ceIN Date: 8/15/2022 conznnt values BMP Oeslg t Spttlflmtlans list 2013 Draft Stds & Spea calculation cells Site Information Post -Development Project (Treatment Volume and Loads) r r rreal Asoas 115ok Csons DsoM Po Open SPace(iQeLl-vmm�umed,proroded forest/open space or rdorestee land Marugetl Turl p[resl-d4uNed, gaded for aMsoromerturtmM1emawM/man ee 3.]z az9ImpeMous 13"�3. [over laved 3.11 0.19 iConstant5 Annual Rainfall (inched 03 Target Rainfall Ewnt lincM1esl 1.to m1al PM1mpnnms(TP) EMO(.9/L) 1 0.26 Total rvivngen(m) EMC(mg/q 1.e6 Target TP mad (Ib/aaeM) 0.41 Pl (umdess comeron facmr) 0.90 nunnN CnaMeienae 1p 1 ASolls Bsells Csoils DSod,; Fares4open spare 0.02 0.03 O.M 0.05 Managed Tuff 0.15 0.20 0.22 0.25 ImpeMous Cover 0.95 095 095 0.95 For¢t/Open Spate Co.,(acrie) 0.00 Trea(aaee-ft) a 0.3293 Treatment Volume (cubic feet) 30,3/0 TP Wad(lb/yr) 9.01 Tel maepb r 60.07 Ln rmationaiPurearesmilirl Weighted Rv(fore.) 0.00 %Forest 0% Managed Turf Cover(acrie) 0.01 Weighted Rv (taM 0.20 %Managed Turf 55% Imperdous Cwer(acres) 3.30 Rv(Imperdous) 0.95 %Imperdous 65% Site area (acres) 7.31 Site RV 0.50 Virginia Runoff Reduction Method Workeheet DEQ Virginia Runoff Reduction Method New Development Compliance Spreadsheet - Version 3.0 LIMP Design Specifications List: 2013 Draft Stds & Specs Site Summary Project Title: Avon Site Date: 44788 Total Rainfall= 43 inches Site Land Cover Summary A soils R Soils C Soils D Soils Totals %of Total Forest/Open (acres( 0.00 0.00 0.00 0.00 0.00 0 Managed Turf (acres) 1 0.00 3.72 0.00 0.29 4.01 55 Impervious Cover (acres) 1 0.00 3.11 0.00 0.19 3.30 45 7.31 100 Site Tv and Land Cover Nutrient Loads Site Rv 0.54 Treatment Volume fts 14,344 TP Load (lb/yr) 9.01 TN Load (lb/yr) 64.47 Total TP Load Reduction Required (lb/yr) 6.02 Site Compliance Summary Total Runoff Volume Reduction (ft) 0 Total TP Load Reduction Achieved (lb/yr) 0.00 Total TN Load Reduction Achieved (lb/yr) 0.00 Remaining Post Development TP Load 9.01 (lb/yr) Remaining TP Load Reduction (lb/yr) 6.02 Required Summary Print Virginia Runoff Reduction Method Woftheet Drainage Area Summary DA. A D.A. B D.A. C D.A. D D.A. E Total Forest/Open (acres( 0.00 0.00 0.00 0.00 0.00 0.00 Managed Turf(acros) 0.00 0.00 0.00 0.00 0.00 0.00 Impervious Cover(acrm) 0.00 0.00 0.00 0.00 0.00 0.00 Total Area (acres) 0.00 0.00 0.00 0.00 0.00 0.00 Drainage Area Compliance Summary D.A. A D.A. B D.A. C D.A. D D.A. E Total TP Load Reduced (lb/yr) 1 0.00 0.00 1 0.00 1 0.00 0.00 0.00 TN Load Reduced (lb/yr) 1 0.00 0.00 1 0.00 1 0.00 0.00 0.00 Summary Print Virginia Runotf Reduction Method Worksheet ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Runoff Volume and CN Calculations 1-year storm 2-year storm 10-year storm Target Rainfall Event (in) 1 0.00 0.00 0.00 Drainage Areas RV & CN Drainage Area A Drainage Area B Drainage Area C Drainage Area D Drainage Area E CN 0 0 0 0 0 RR (fta) 0 0 0 0 0 1-year return period RV wa RR (wz-In) 0.00 0.00 0.00 0.00 0.00 RV w RR (wsin) 0.00 0.00 0.00 0.00 0.00 cN adjusted 0 0 0 0 0 2-year return period RV wa RR (.sin) 0.00 0.00 0.00 0.00 0.00 RV w RR (wsin) 0.00 0.00 0.00 0.00 0.00 CN adjusted 0 0 0 0 0 10-year return period For RVwa RR(En) 0.00 0.00 0.00 0.00 0.00 RV w Iwsin) 0.00 0.00 0.00 0.00 0.00 cN adjusted 0 0 0 0 0 Summary Print APPENDIX B: BMP Routings 4S 5S O Offsite AO Propo ed SWM A01 1P O 6S 7S 8S O SWM, %B pass A01 Offsit A03 Pr osed SWM A03 1R 2P A01 ZSWM2 2R <- 9S A03 Bypass A03 Subcat Reach 4on Llnk ACSA Detention - AO3 Prepared by Dewberrv- Richmond Office Rainfall Events Listing (selected events) Printed 9/9/2022 Event# Event Storm Type Curve Mode Duration B/B Depth AMC Name (hours) (inches) 1 1 YEAR Type II 24-hr Default 24.00 1 3.04 2 2 10 YEAR Type II 24-hr Default 24.00 1 5.56 2 3 100 YEAR Type II 24-hr Default 24.00 1 9.14 2 ACSA Detention - AO3 Prepared by Dewberry- Richmond Office Type/1 24-hr 1 YEAR Rainfall=3.04" Summary for Subcatchment 4S: Mite AO1 Runoff = 2.00 cfs @ 11.97 hrs, Volume= 0.091 af, Depth> 0.83" Routed to Pond 1 P : SWM1 Printed 9/9/2022 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type II 24-hr 1 YEAR Rainfall=3.04" Area (ac) CN Descriotion " 0.650 61 Managed Turf- B " 0.240 55 Wooded - B " 0.430 98 Impervious 1.320 72 Weighted Average 0.890 67.42% Pervious Area 0.430 32.58% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Subcatchment 4S: Offsite AO1 Hydrograph i z.00�--r__r__r _-ir__7__T__r__r 2 " .Type 11'1 24-h�r 1 DEAR Rai6fallT3.04" Rwnbff Areh=1.320 at: Rll#ngff', V910me=,0.09�,1 4f Runoff Depth>0.83"' G - Tai 5.;01trtilh CAN=72 11 12 13 Time (hours) ■ Runoff ACSA Detention - A03 Prepared by Dewberry- Richmond Office Type/1 24-hr 1 YEAR Rainfall=3.04" Summary for Subcatchment 5S: Proposed SWM A01 Runoff = 11.16 cfs @ 11.99 hrs, Volume= 0.538 af, Depth> 1.28" Routed to Pond 1 P : SWM1 Printed 9/9/2022 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type II 24-hr 1 YEAR Rainfall=3.04" Area facl CN Descriotion " 2.480 61 Managed Turf- Onsite " 2.570 98 Impervious - Onsite 5.050 80 Weighted Average 2.480 49.11 % Pervious Area 2.570 50.89% Impervious Area Tc Length Description 7.0 Direct Entry, Subcatchment 5S: Proposed SWM A01 Hydrograph _l__L__ L__L__I___I__J__J__1__L__L__ 12 I I I I I I I I I I I I I I I I I I I I I I I --�---�--�--�--�--�--L--�---'--L_ 11.1ficfa-J--L--L--'---'--J--J--L--�--L--'- „ -- -- -- -- -- -- ----- - - -- -- TypQ_1I'124-Mr - 10 1 YEAR Rainfall=*.OW I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I 9 'Rwnbff Areti=5.050 at: 1 1 --r--1--7--7--7--T--r--r--I --1--, --T--T--T--r--I 8- ' - ; Wnpff��V_plylme_=,'0.$3$-elf_- __�___ __�__ 7__ T__ �__ r__ �___�__1 ___i___i__y__t__r__r__r__i___i__.� k noffboih>l_28k O 6' 1 1 1 1 1 1 1 1 1 1 1 1 /� 1 7 1 y1m- 1y^ 1 1 1 1 1 1 1 1 1 1 1 1 TaI�t�-Mirlk- 1L I I I I I I I I I I I I I I I I I I I I I I --L--1--J--J--1--1--L--L--1---1--J--J--1--L--L--1---1--J--1- '=�VX a I 1 1 1 1 I I 1 1 1 1 1 1 1 1 I I 1 1 1 1 --L--'--J--,--1--1--L--L--'---'--J -----1--L--L--1---1--J--1--1--1--L-- 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3 I 1 1 1 1 I I I I I I 1 1 1 1 I I 1 1 1 1 2 I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) ■ Runoff ACSA Detention - A03 Type/1 24-hr 1 YEAR Rainfall=3.04" Prepared by Dewberry- Richmond Office Printed 9/9/2022 Summary for Subcatchment 6S: Bypass A01 Runoff = 1.48 cfs @ 12.00 hrs, Volume= 0.074 af, Depth> 0.78" Routed to Reach 1 R : AO Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type II 24-hr 1 YEAR Rainfall=3.04" Area (ac) CN Descriotion " 0.840 61 Managed Turf- Onsite " 0.300 98 Impervious - Onsite 1.140 71 Weighted Average 0.840 73.68% Pervious Area 0.300 26.32% Impervious Area Tc Length 7.0 1 Description Direct Entry, Subcatchment 6S: Bypass A01 Hydrograph i i I I i i I I i i I I I I I I I I i i i i i i I I I I I I r 4 ---- I Time (houm) i i I I I i i I I I I i i I I I i i I I I I i i I I I i i I I I I Type II'124-hr 1 YEAR RainfallT3.04 Rwnbff Areti=1.140 at: I I I � � I I I I R-Lp'ngff',VpCome=,`OVT Cf kunoff bipih>0.78�' �I,I,I,��IIII Tc=7.0 nib I I I CAN=7!1 ■ Runoft ACSA Detention - A03 Prepared by Dewberrv- Richmond Office Type 11 24-hr 1 YEAR Rainfall=3.04" Summary for Subcatchment 7S: Offsite A03 Runoff = 0.02 cfs @ 11.99 hrs, Volume= 0.001 af, Depth> 0.38" Routed to Pond 2P : SWM2 Printed 9/9/2022 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type II 24-hr 1 YEAR Rainfall=3.04" Area (ac) CN Description 0.040 61 Managed Turf- B 0.040 100.00% Pervious Area Tc Length Slope Velocity Capacity Description 5.0 Direct Entry, Subcatchment 7S: Offsite A03 Hydrograph _---�i--T 0.024 ----------T--f---- ,--------}--i- - I 0.023 0.02 Cfe 0.022 --I--,--r--r--r--I--,--'I--r--r r--r' 0.021 -----1--1-----J--1--L--'-- � II � Syr.__ -_L-- Type 'rr-- 0.02 ------'--`-------'----�-- 1, YEAR a�li"1 lA_ 0.019 7 1 T _ygJ—_L" -,' -r-r-r-I-,-r- Runoff Area=0.-040a& - 0.015 R-unQu�lump=p.00 I 0.014 ,-- r--r- - - -- �EREa�i�nf --r--r-_1_____hL__L_ 0.009 I I I I I I I I I 0.00s - -- _ 0.004 —- r- ---- - r--r--�---�--r-r--r �--,--�--r-- 9.993 I I I I I I I I I I I I I I I I I—�--�--}-- 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) ❑ Runoff ACSA Detention - AO3 Prepared by Dewberrv- Richmond Office Type 11 24-hr 1 YEAR Rainfall=3.04" Printed 9/9/2022 Summary for Subcatchment 8S: Proposed SWM AO3 Runoff = 0.62 cfs @ 11.97 hrs, Volume= 0.028 af, Depth> 1.16" Routed to Pond 2P : SWM2 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type II 24-hr 1 YEAR Rainfall=3.04" Area (ac) CN Description ' 0.160 61 ' 0.130 98 0.290 78 Weighted Average 0.160 55.17% Pervious Area 0.130 44.83% Impervious Area Tc Length Slope Velocity Capacity Description 5.0 0.1 Direct Entry, Subcatchment 8S: Proposed SWM AO3 Hydrograph C I I I _L- I - L------J I I I --J - - I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I -I -T -f I I I I I I I I I I I I I I I I I I I I I I I 1 1 I I I I I I I I I I I I I I I I I I I I I I I I I I I I - -y -y I -y I -Y I -r -I I I I I I Type II 24-hr 1 YEAR Rainfa11:;3.04" Runoff Area=9.290Ta1�_ Runoff Vo1gm0=4.02$-0f- --III Runoff IlDepth>1:9f1'- Tc=5.0 mih- I I I I I ----------------------------- I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) ❑ Runoff ACSA Detention - A03 Prepared by Dewberrv- Richmond Office Type 11 24-hr 1 YEAR Rainfall=3.04" Printed 9/9/2022 Summary for Subcatchment 9S: Bypass A03 Runoff = 0.54 cfs @ 11.96 hrs, Volume= 0.024 af, Depth> 1.55" Routed to Reach 2R : A03 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type II 24-hr 1 YEAR Rainfall=3.04" Area (ac) CN Description ' 0.040 61 Managed Turf- B ' 0.080 98 Impervious ' 0.070 80 Managed Turf- D 0.190 84 Weighted Average 0.110 57.89% Pervious Area 0.080 42.11% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Subcatchment 9S: Bypass A03 Hydrograph 0.6 I I I I I I I I I 0.55 I I I I I I I I I 1 0.5 I I I I I I I I I 1 0.45 I 0.4 0.35 III N -------------------------- - 0.3 I I I I c LL I I I I I I I I I I I I 0.25 I I I I I I I I I I I 0 2 I I 0.15 i i i i i I I I I I 0.1 I I I I I I I I Time (horns) 17 u112q-pr- 7-SEA' R-Ra➢nfa11;;1G4"- Runbff'JAkeA=a A9d at I I I I I #runoff V00m0=o=424-0# -----Runoff# 111Deptl4:"' I I I I I I I I I I I --- I I I I I I I I I I I I 1 I I I I I I I I I I I I I I I I I I I I I I I I I I I 1 ❑ Runoff ACSA Detention - A03 Prepared by Dewberrv- Richmond Office Type 11 24-hr 1 YEAR Rainfall=3.04" Printed 9/9/2022 Summary for Reach 1 R: A01 Inflow Area = 7.510 ac, 43.94% Impervious, Inflow Depth > 0.52" for 1 YEAR event Inflow = 1.67 cfs @ 12.00 hrs, Volume= 0.327 of Outflow = 1.57 cfs @ 12.02 hrs, Volume= 0.325 af, Atten= 6%, Lag= 1.7 min Routed to Reach 2R : A03 Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Max. Velocity= 0.67 fps, Min. Travel Time= 2.8 min Avg. Velocity = 0.47 fps, Avg. Travel Time= 4.0 min Peak Storage= 262 cf @ 12.02 hrs Average Depth at Peak Storage= 0.16' , Surface Width= 14.89' Bank -Full Depth= 10.00' Flow Area= 415.0 sf, Capacity= 2,916.59 cfs 14.00' x 10.00' deep channel, n= 0.050 Earth, long dense weeds Side Slope Z-value= 2.5 3.0 7' Top Width= 69.00' Length= 111.6' Slope= 0.0055 7' Inlet Invert= 504.58', Outlet Invert= 503.97' Reach 1 R: A01 Hydrograph , 67 ck Inflow Area=7,.516 ac Avg. Flown DepthTO.'16' Max Vel=0.67 fps n=0.050 S=0i0©55 T Capacity=2'91 G.6a9 Ccfs Ili011iFR F1011iiiiiiiiiiiiiiiiiiiiiiiiii3i ■ Inflow ❑ OWlow ACSA Detention - A03 Prepared by Dewberrv- Richmond Office Type 11 24-hr 1 YEAR Rainfall=3.04" Printed 9/9/2022 Summary for Reach 2R: A03 Inflow Area = 8.030 ac, 43.71 % Impervious, Inflow Depth > 0.57" for 1 YEAR event Inflow = 2.18 cfs @ 12.01 hrs, Volume= 0.379 of Outflow = 2.18 cfs @ 12.01 hrs, Volume= 0.379 af, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Reach 2R: A03 Hydrograph ❑ InHow ❑ Outflow Time (hours) ACSA Detention - A03 Prepared by Dewberrv- Richmond Office Type 11 24-hr 1 YEAR Rainfall=3.04" Summary for Pond 1P: SWM1 Printed 9/9/2022 Inflow Area = 6.370 ac, 47.10% Impervious, Inflow Depth > 1.18" for 1 YEAR event Inflow = 13.09 cfs @ 11.98 hrs, Volume= 0.629 of Outflow = 0.25 cfs @ 17.94 hrs, Volume= 0.252 af, Atten= 98%, Lag= 357.5 min Primary = 0.25 cfs @ 17.94 hrs, Volume= 0.252 of Routed to Reach 1 R : A01 Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Peak Elev= 524.22' @ 17.94 hrs Surf.Area= 0.129 ac Storage= 0.408 of Plug -Flow detention time= 356.4 min calculated for 0.252 of (40% of inflow) Center -of -Mass det. time= 223.1 min ( 1,068.6 - 845.5 ) Volume Invert Avail.Storage Storage Description #1 518.50' 1.583 of Custom Stage Data (Prismatic)Listed below Elevation Surf.Area Inc.Store Cum.Store (feet) (acres) (acre-feet) (acre-feet) 518.50 0.000 0.000 0.000 519.00 0.031 0.008 0.008 520.00 0.046 0.038 0.046 521.00 0.063 0.054 0.101 522.00 0.082 0.073 0.173 523.00 0.102 0.092 0.265 524.00 0.124 0.113 0.378 525.00 0.147 0.135 0.514 526.00 0.172 0.159 0.673 527.00 0.198 0.185 0.858 528.00 0.226 0.212 1.070 529.00 0.256 0.241 1.311 530.00 0.287 0.272 1.583 Device Routing Invert Outlet Devices #1 Primary 518.50' 30.0" Round Culvert L= 102.0' RCP, groove end projecting, Ke= 0.200 Inlet / Outlet Invert= 518.50' / 515.00' S= 0.0343 '/' Cc= 0.900 n= 0.013, Flow Area= 4.91 sf #2 Device 1 518.50' 2.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Device 1 525.90' 16.0" W x 12.0" H Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #4 Device 1 526.90' 60.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=0.25 cfs @ 17.94 hrs HW=524.22' TW=504.62' (Dynamic Tailwater) t1=Culvert (Passes 0.25 cfs of 62.46 cfs potential flow) 2=Orifice/Grate (Orifice Controls 0.25 cfs @ 11.43 fps) 3=Orifice/Grate ( Controls 0.00 cfs) =Orifice/Grate ( Controls 0.00 cfs) ACSA Detention - A03 Prepared by Dewberry- Richmond Office Type // 24-hr 1 YEAR Rainfall=3.04" Printed 9/9/2022 Pond IP: SWM7 Hydrograph / I 14 '�■Pnmary 13 -i-- iiii ii -��IOIW}/1rp�V.IQaV- I I I I I I I I _ II 12, -Storage=I 0�40& a#- ,6 �' __I __l__7__r__i__�__r__ 9 -rr 7_r__rJJ --r- _ 1 1 I I I I I I I I I _1 _L _I _J _1_L _I _J _J _L _I _J _1 _L_J _J _1 _L _L_J a I I I I I I I I I I I I / I I I I I I O7-r T -I -7 -r T-1 -1 -r T-1 -T -r -I -1 -T -r -r -I _L _I__J _1 _L_ I__J _1 _L _L_J 6 I I I I I I I I I I I I I / 4 I I I I I I I I I I I I I I 3- 2- 4 5 6 7 8 9 10 11 12 13 Time (hours) ACSA Detention - A03 Prepared by Dewberrv- Richmond Office Type 11 24-hr 1 YEAR Rainfall=3.04" Summary for Pond 2P: SWM2 Printed 9/9/2022 Inflow Area = 0.330 ac, 39.39% Impervious, Inflow Depth > 1.06" for 1 YEAR event Inflow = 0.64 cfs @ 11.97 hrs, Volume= 0.029 of Outflow = 0.21 cfs @ 12.07 hrs, Volume= 0.029 af, Atten= 67%, Lag= 6.5 min Primary = 0.21 cfs @ 12.07 hrs, Volume= 0.029 of Routed to Reach 2R : A03 Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Peak Elev= 530.92' @ 12.07 hrs Surf.Area= 615 sf Storage= 284 cf Plug -Flow detention time= 8.8 min calculated for 0.029 of (100% of inflow) Center -of -Mass det. time= 8.3 min ( 858.2 - 850.0 ) Volume Invert Avail.Storage Storage Description #1 530.00' 2,392 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 530.00 0 0 0 531.00 667 334 334 532.00 1,018 843 1,176 533.00 1,414 1,216 2,392 Device Routing Invert Outlet Devices #1 Primary 530.00' 3.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #2 Primary 531.90' 20.0' long x 0.7' breadth Broad -Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 Coef. (English) 2.76 2.82 2.93 3.09 3.18 3.22 3.27 3.30 3.32 3.31 3.32 Primary OutFlow Max=0.21 cfs @ 12.07 hrs HW=530.92' TW=0.00' (Dynamic Tailwater) �1=Orifice/Grate (Orifice Controls 0.21 cfs @ 4.30 fps) 2= B road-C rested Rectangular Weir( Controls 0.00 cfs) ACSA Detention - A03 Prepared by Dewberry- Richmond Office Type // 24-hr 1 YEAR Rainfall=3.04" Printed 9/9/2022 Pond 2P: SWM2 Hydrograph ■ITIM 0.7 ' i _____i__r________i__r_ _r__r __- i i i__i__, __r __i__i__ Primary 0.6 T__ T__�_ T__T__� P k :_ eV_=_3P:8 L _L_ --r-r--r--r-r--r--r--� �_ r__ - � _ � +_1 --r- r_ p��� �(, -I --- Lt�re:F28 -d- 0.5 0.45 ,.. , LL 0.25 021 �N -J--L-_'--J--J--L----J--L----J-- 0.15 In 1 4 5 6 7 8 9 10 11 12 13 Time (hours) ACSA Detention - A03 Prepared by Dewberrv- Richmond Office Type II 24-hr 10 YEAR Rainfall=5.56" Summary for Pond 1P: SWM1 Printed 9/9/2022 Inflow Area = 6.370 ac, 47.10% Impervious, Inflow Depth > 3.23" for 10 YEAR event Inflow = 35.24 cfs @ 11.98 hrs, Volume= 1.713 of Outflow = 4.86 cfs @ 12.26 hrs, Volume= 1.045 af, Atten= 86%, Lag= 16.9 min Primary = 4.86 cfs @ 12.26 hrs, Volume= 1.045 of Routed to Reach 1 R : A01 Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Peak Elev= 526.92' @ 12.26 hrs Surf.Area= 0.196 ac Storage= 0.844 of Plug -Flow detention time= 209.2 min calculated for 1.045 of (61% of inflow) Center -of -Mass det. time= 99.5 min ( 916.6 - 817.2 ) Volume Invert Avail.Storage Storage Description #1 518.50' 1.583 of Custom Stage Data (Prismatic)Listed below Elevation Surf.Area Inc.Store Cum.Store (feet) (acres) (acre-feet) (acre-feet) 518.50 0.000 0.000 0.000 519.00 0.031 0.008 0.008 520.00 0.046 0.038 0.046 521.00 0.063 0.054 0.101 522.00 0.082 0.073 0.173 523.00 0.102 0.092 0.265 524.00 0.124 0.113 0.378 525.00 0.147 0.135 0.514 526.00 0.172 0.159 0.673 527.00 0.198 0.185 0.858 528.00 0.226 0.212 1.070 529.00 0.256 0.241 1.311 530.00 0.287 0.272 1.583 Device Routing Invert Outlet Devices #1 Primary 518.50' 30.0" Round Culvert L= 102.0' RCP, groove end projecting, Ke= 0.200 Inlet / Outlet Invert= 518.50' / 515.00' S= 0.0343 '/' Cc= 0.900 n= 0.013, Flow Area= 4.91 sf #2 Device 1 518.50' 2.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Device 1 525.90' 16.0" W x 12.0" H Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #4 Device 1 526.90' 60.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=4.86 cfs @ 12.26 hrs HW=526.92' TW=504.93' (Dynamic Tailwater) t1=Culvert (Passes 4.86 cfs of 79.11 cfs potential flow) 2=Orifice/Grate (Orifice Controls 0.30 cfs @ 13.90 fps) 3=Orifice/Grate (Orifice Controls 4.40 cfs @ 3.30 fps) =Orifice/Grate (Weir Controls 0.15 cfs @ 0.47 fps) ACSA Detention - A03 Prepared by Dewberry- Richmond Office Type ll 24-hr 10 YEAR Rainfall=5.56" Printed 9/9/2022 Pond IP: SWM7 Hydrograph _ _J -1 _-1 -F -F_ ■Inflow __ __�__,_ '--�--'--"__---'------"--i------'-- ■Prima ry 38 I 35.za GB I I I I -r 36 ,' I - n lt�vvWe �6;3701a�- 34 I I I --I--�--r--r--r--r-,--r--r-�--� --r - - I r r r- 32 30 r 1 1 1 1 1 1 1 1 1 1 1 Iy� Ih IIQj 28 \Id�a\}jr ` A�$j{I �i�IIiLII� L__I__SbDrA"T�Y'S4taf- 26 24 •' _{ _F_J .@ 22 _I -4 -F _I _I _4 -1 _I _� _I 26 3 , - -7 -Y -Y -I -I -Y -Y -I --I -y -r -I -7 -T -Y -I -� 0 18 __-__r__r__r__I__ 16 14 12 ___________________----- ___ __________________________ 10 6 4.W�y 4 5 6 7 8 9 10 11 12 13 Time (hours) ACSA Detention - A03 Prepared by Dewberrv- Richmond Office Type II 24-hr 10 YEAR Rainfall=5.56" Summary for Pond 2P: SWM2 Printed 9/9/2022 Inflow Area = 0.330 ac, 39.39% Impervious, Inflow Depth > 3.01" for 10 YEAR event Inflow = 1.82 cfs @ 11.96 hrs, Volume= 0.083 of Outflow = 0.71 cfs @ 12.06 hrs, Volume= 0.083 af, Atten= 61 %, Lag= 5.9 min Primary = 0.71 cfs @ 12.06 hrs, Volume= 0.083 of Routed to Reach 2R : A03 Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Peak Elev= 531.94' @ 12.06 hrs Surf.Area= 996 sf Storage= 1,113 cf Plug -Flow detention time= 24.5 min calculated for 0.083 of (100% of inflow) Center -of -Mass det. time= 24.0 min ( 844.5 - 820.6 ) Volume Invert Avail.Storage Storage Description #1 530.00' 2,392 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 530.00 0 0 0 531.00 667 334 334 532.00 1,018 843 1,176 533.00 1,414 1,216 2,392 Device Routing Invert Outlet Devices #1 Primary 530.00' 3.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #2 Primary 531.90' 20.0' long x 0.7' breadth Broad -Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 Coef. (English) 2.76 2.82 2.93 3.09 3.18 3.22 3.27 3.30 3.32 3.31 3.32 Primary OutFlow Max=0.71 cfs @ 12.06 hrs HW=531.94' TW=0.00' (Dynamic Tailwater) �1=Orifice/Grate (Orifice Controls 0.32 cfs @ 6.48 fps) 2= B road-C rested Rectangular Weir(Weir Controls 0.39 cfs @ 0.53 fps) ACSA Detention - A03 Prepared by Dewberry- Richmond Office Pond 2P: SWM2 Hydrograph Type ll 24-hr 10 YEAR Rainfall=5.56" Printed 9/9/2022 ■ Inflow ■ Primary Inflow ,Are00:,330 ',ac PoAk F-10=¢3,1.941 Storage=1,1 �'13, cf a 71 ch 1 2 3 4 5 6 7 8 9 10 11 12 13 Time (houm) ACSA Detention - A03 Prepared by Dewberrv- Richmond Office Type 11 24-hr 100 YEAR Rainfall=9.14" Summary for Pond 1P: SWM1 Printed 9/9/2022 Inflow Area = 6.370 ac, 47.10% Impervious, Inflow Depth > 6.49" for 100 YEAR event Inflow = 68.59 cfs @ 11.98 hrs, Volume= 3.443 of Outflow = 63.36 cfs @ 12.01 hrs, Volume= 2.754 af, Atten= 8%, Lag= 1.9 min Primary = 63.36 cfs @ 12.01 hrs, Volume= 2.754 of Routed to Reach 1 R : A01 Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Peak Elev= 527.95' @ 12.01 hrs Surf.Area= 0.225 ac Storage= 1.059 of Plug -Flow detention time=129.4 min calculated for 2.754 of (80% of inflow) Center -of -Mass det. time= 49.0 min ( 846.7 - 797.6 ) Volume Invert Avail.Storage Storage Description #1 518.50' 1.583 of Custom Stage Data (Prismatic)Listed below Elevation Surf.Area Inc.Store Cum.Store (feet) (acres) (acre-feet) (acre-feet) 518.50 0.000 0.000 0.000 519.00 0.031 0.008 0.008 520.00 0.046 0.038 0.046 521.00 0.063 0.054 0.101 522.00 0.082 0.073 0.173 523.00 0.102 0.092 0.265 524.00 0.124 0.113 0.378 525.00 0.147 0.135 0.514 526.00 0.172 0.159 0.673 527.00 0.198 0.185 0.858 528.00 0.226 0.212 1.070 529.00 0.256 0.241 1.311 530.00 0.287 0.272 1.583 Device Routing Invert Outlet Devices #1 Primary 518.50' 30.0" Round Culvert L= 102.0' RCP, groove end projecting, Ke= 0.200 Inlet / Outlet Invert= 518.50' / 515.00' S= 0.0343 '/' Cc= 0.900 n= 0.013, Flow Area= 4.91 sf #2 Device 1 518.50' 2.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Device 1 525.90' 16.0" W x 12.0" H Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #4 Device 1 526.90' 60.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=63.26 cfs @ 12.01 hrs HW=527.95' TW=506.15' (Dynamic Tailwater) t1=Culvert (Passes 63.26 cfs of 84.58 cfs potential flow) 2=Orifice/Grate (Orifice Controls 0.32 cfs @ 14.73 fps) 3=Orifice/Grate (Orifice Controls 7.95 cfs @ 5.96 fps) =Orifice/Grate (Weir Controls 54.99 cfs @ 3.35 fps) ACSA Detention - A03 Prepared by Dewberry- Richmond Office Pond IP: SWM7 Hydrograph Type II 24-hr 100 YEAR Rainfall=9.14" Printed 9/9/2022 - 4 5 6 7 8 9 10 11 12 13 Time (hoes) ■ Inflow ■ Primary ACSA Detention - A03 Prepared by Dewberrv- Richmond Office Type 11 24-hr 100 YEAR Rainfall=9.14" Summary for Pond 2P: SWM2 Printed 9/9/2022 Inflow Area = 0.330 ac, 39.39% Impervious, Inflow Depth > 6.19" for 100 YEAR event Inflow = 3.63 cfs @ 11.96 hrs, Volume= 0.170 of Outflow = 3.60 cfs @ 11.97 hrs, Volume= 0.170 af, Atten= 1%, Lag= 0.5 min Primary = 3.60 cfs @ 11.97 hrs, Volume= 0.170 of Routed to Reach 2R : A03 Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Peak Elev= 532.05' @ 11.97 hrs Surf.Area= 1,039 sf Storage= 1,230 cf Plug -Flow detention time=19.1 min calculated for 0.170 of (100% of inflow) Center -of -Mass det. time= 18.6 min ( 819.3 - 800.6 ) Volume Invert Avail.Storage Storage Description #1 530.00' 2,392 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 530.00 0 0 0 531.00 667 334 334 532.00 1,018 843 1,176 533.00 1,414 1,216 2,392 Device Routing Invert Outlet Devices #1 Primary 530.00' 3.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #2 Primary 531.90' 20.0' long x 0.7' breadth Broad -Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 Coef. (English) 2.76 2.82 2.93 3.09 3.18 3.22 3.27 3.30 3.32 3.31 3.32 Primary OutFlow Max=3.60 cfs @ 11.97 hrs HW=532.05' TW=0.00' (Dynamic Tailwater) �1=Orifice/Grate (Orifice Controls 0.33 cfs @ 6.68 fps) 2= B road-C rested Rectangular Weir(Weir Controls 3.27 cfs @ 1.08 fps) ACSA Detention - A03 Prepared by Dewberry- Richmond Office Type II 24-hr 100 YEAR Rainfall=9.14" Printed 9/9/2022 Pond 212: SWM2 Hydrograph ' ' � -�- ' ' � -�' --�- ' ■Inflow 4 d°1 1 ■Primary 60o Inflow 'IAre00:,330'lac - - Peak-�FeV=¢3Z p5' - 3 Storage=1�230 cf „ „ T9 2- LL I I I I I I I i i I I i i I I I i I I i i I I i i I I I i 1 4 5 6 7 8 9 10 11 12 13 Time (hours) APPENDIX C: Water Quantity Calculations Avon Maintenance Yard Albemarle County Dewberry Water Resources Engineering STEP 1: Determine the Pre Develope Pre Developed Conditions Weighhd CN= 56.0 Area (ac) = 6.37 P(in.)= 3.04 STEP 2: Determine the peak dischim Pre Developed Discharge S 7.9 In 1.6 Q(in) 0.2 in Volume 0.123 ac-ft Forested, and Post Develope Forested Conditions Weighted CN= 55.0 Area (ac) = 6.37 P(in.)= 3.04 Forested Conditions Discharge S 8.2 Is 1.6 Q(in) 0.2 in Volume 0.109 ac-ft Total Forested Peak Discharge 0.34 cfs value using Runoff Reduction provided in BUN BMP Runoff fts fls to to OWfetl: AO1 Chenmel Type- NatuM within the disturbed area Post Developed Conditions N1 righted (:S = 78.2 Area (or) = 6.19 P (in.) = 3.04 Post Development Discharge S 2.8 Is 0.6 Q (in) 1.2 in Volume 0.603 ac-ft Total Predevelopment Discharge Qpost without RR = Qpmt with RR= Adjusted CN = Engineer: SPC Checker: HCG 0.69 cfs 12 12 78 Total = 0 ft STEP 4: Calculate Qsm,.,ue using the energy balance equation. Only apply the improvement factor to the disturbed area. Energy Balance Equation: Q, S lEx(Q1u,, ,,x RVere-Dne.,) / RVo,, Improvement Factor 0.8 Qsa,5 [Total Predevelopment Discharge(Offsite Volume+(Improvement Factor x Pre -Developed Volume)/(Post-Development Volume+ 011site Volume)] Qsa—. Q I I cfs STEP 5: Calculated Maximum Allowable Peak Discharge. mum Allowable Peak Discharge = Maximum (Q� , Qsiw ,,), never greater than Total PreDevelopment Discharge = Total Forest Peak Discharge x (Forest Volume + Offsite Volume)I(Post-Development Volume +Offsite Volume) 0.06 cfs cable Site Area Discharge + OfFsite Area Peak Discharge - Detained = gy Balance) 0.I I cfs 2.00 cfs Allowable 2.11 cfs a..n is less than the Maximum Allowable Peak 1.57 cfs Adequate 4S 5S 1 S 2S 3S Offsite AO Prop d SwM AO1 Existing DA Existing Offsite A01 Forested YYYJJJ 1 P �/ 6S SWM1 Bypass A01 \\rl 1 RCS A01 Subcat Reach On Link Routing Diagram for ACSA Detention - A01 Prepared by Dewberry- Richmond Office, Printed 9/9/2022 FHydroCAD@ 10.20-21b s/n 05760 © 2021 HydroCAD Software Solutions LLC ACSA Detention - AO1 Prepared by Dewberrv- Richmond Office Rainfall Events Listing (selected events) Event# Event Storm Type Curve Mode Duration B/B Depth AMC Name (hours) (inches) 1 1 YEAR Type II 24-hr Default 24.00 1 3.04 2 2 10 YEAR Type II 24-hr Default 24.00 1 5.56 2 Printed 9/9/2022 ACSA Detention - A01 Prepared by Dewberry- Richmond Office Type/1 24-hr 1 YEAR Rainfall=3.04" Printed 9/9/2022 Summary for Subcatchment 1S: Existing DA Runoff = 0.69 cfs @ 12.16 hrs, Volume= 0.122 af, Depth> 0.23" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type II 24-hr 1 YEAR Rainfall=3.04" Area (ac) CN Descriotion " 0.310 61 Managed Turf- B " 5.950 55 Wooded - B " 0.110 98 Impervious 6.370 56 Weighted Average 6.260 98.27% Pervious Area 0.110 1.73% Impervious Area Tc Length Slope Velocity Capacity Description 15.8 Direct Entry, Subcatchment 1S: Existing DA Hydrograph --I----,--1rr--I-1--,--Tr--I ----,--1Tr--I----,TT--I - 0.75 , 0...7 -*y�rn,I,, �H 0.65 ____-I;IIIiIIIII 0.6 1��YEiRnfalf*.04 055 _RW^/prpM�6L39Da _1rfi;IIII________1Ttii;IIIII____ __Lrrh;IIIII____ ____- _ ____y-II,IIIIIIIII __Jyyy4;IIIII 05 Auvf Yq1uM�h2Lg o__r__r__ 0.45 U.4 _Fkun0fFb0th>t3lr- -____ -___-____- -____-_____- -- -____-LirFII'�FII____-____-IiIIIII'�IIII 2 0.35 jcy mtnl t 1:� 0.3-q�I 0.25 02 0.15 01 0.051, 1 1 I I I I I I 2 3 4 5 6 7 8 9 10 11 12 13 Time (hour) ■ Runofi ACSA Detention - AO1 Prepared by Dewberrv- Richmond Office Type 11 24-hr 1 YEAR Rainfall=3.04" Printed 9/9/2022 Summary for Subcatchment 2S: Existing Offsite AO1 Runoff = 2.00 cfs @ 11.97 hrs, Volume= 0.091 af, Depth> 0.83" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type II 24-hr 1 YEAR Rainfall=3.04" Area (ac) CN Description 0.650 61 Managed Turf- B 0.240 55 Wooded - B 0.430 98 Impervious 1.320 72 Weighted Average 0.890 67.42% Pervious Area 0.430 32.58% Impervious Area Tc Length Slope Velocity Capacity Description I—i-\ If --A /f1/f1\ /H/oo..\ /.do\ 5.0 Direct Entry, Subcatchment 2S: Existing Offsite AO1 Hydrograph ❑ Runoff 2 Type II 24-hr 1 YEAR Rainfall=3.04" Runoff Area=1.320 ac Runoff Volume=0.091 of Runoff Depth>0.83" Tc=5.0 min I I �N CN=72 9 1 2 3 4 5 6 7 8 9 19 11 12 13 14 15 16 17 18 19 29 21 22 23 24 Time (hours) ACSA Detention - AO1 Prepared by Dewberrv- Richmond Office Type 11 24-hr 1 YEAR Rainfall=3.04" Summary for Subcatchment 3S: Forested Runoff = 0.34 cfs @ 12.53 hrs, Volume= 0.107 af, Depth> 0.20" Printed 9/9/2022 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type II 24-hr 1 YEAR Rainfall=3.04" Area (ac) CN Description 6.370 55 Wooded - B 6.370 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 34.9 Direct Entry, Subcatchment 3S: Forested Hydrograph "1 0.36 0.34-iYpe fl-L4ihr __�__ 0.32 1 YEAR Rainfall=3.04"_�L_ 028 Runoff Area�6; 3 70 ac- - - - -,-- - - --, -- T - Runoff a w 022 RunoffDeptfi>0O1r= 0.2 7 r -r-- , T T -r 0 0.18 Tc=34.9 mina ---L-----------1--L--'-- _____ 0.12 0.1 0.08 0.06 0 04 __-r--r--r--r-i__r__r__- 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) ■ Runoff ACSA Detention - AO1 Prepared by Dewberry- Richmond Office Type/1 24-hr 1 YEAR Rainfall=3.04" Summary for Subcatchment 4S: Mite AO1 Runoff = 2.00 cfs @ 11.97 hrs, Volume= 0.091 af, Depth> 0.83" Routed to Pond 1 P : SWM1 Printed 9/9/2022 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type II 24-hr 1 YEAR Rainfall=3.04" Area (ac) CN Descriotion " 0.650 61 Managed Turf- B " 0.240 55 Wooded - B " 0.430 98 Impervious 1.320 72 Weighted Average 0.890 67.42% Pervious Area 0.430 32.58% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Subcatchment 4S: Offsite AO1 Hydrograph i z.00�--r__r__r _-ir__7__T__r__r 2 " .Type 11'1 24-h�r 1 DEAR Rai6fallT3.04" Rwnbff Areh=1.320 at: Rll#ngff', V910me=,0.09�,1 4f Runoff Depth>0.83"' G - Tai 5.;01trtilh CAN=72 11 12 13 Time (hours) ■ Runoff ACSA Detention - A01 Prepared by Dewberry- Richmond Office Type/1 24-hr 1 YEAR Rainfall=3.04" Summary for Subcatchment 5S: Proposed SWM A01 Runoff = 11.16 cfs @ 11.99 hrs, Volume= 0.538 af, Depth> 1.28" Routed to Pond 1 P : SWM1 Printed 9/9/2022 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type II 24-hr 1 YEAR Rainfall=3.04" Area facl CN Descriotion " 2.480 61 Managed Turf- Onsite " 2.570 98 Impervious - Onsite 5.050 80 Weighted Average 2.480 49.11 % Pervious Area 2.570 50.89% Impervious Area Tc Length Description 7.0 Direct Entry, Subcatchment 5S: Proposed SWM A01 Hydrograph _l__L__ L__L__I___I__J__J__1__L__L__ 12 I I I I I I I I I I I I I I I I I I I I I I I --�---�--�--�--�--�--L--�---'--L_ 11.1ficfa-J--L--L--'---'--J--J--L--�--L--'- „ -- -- -- -- -- -- ----- - - -- -- TypQ_1I'124-Mr - 10 1 YEAR Rainfall=*.OW I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I 9 'Rwnbff Areti=5.050 at: 1 1 --r--1--7--7--7--T--r--r--I --1--, --T--T--T--r--I 8- ' - ; Wnpff��V_plylme_=,'0.$3$-elf_- __�___ __�__ 7__ T__ �__ r__ �___�__1 ___i___i__y__t__r__r__r__i___i__.� k noffboih>l_28k O 6' 1 1 1 1 1 1 1 1 1 1 1 1 /� 1 7 1 y1m- 1y^ 1 1 1 1 1 1 1 1 1 1 1 1 TaI�t�-Mirlk- 1L I I I I I I I I I I I I I I I I I I I I I I --L--1--J--J--1--1--L--L--1---1--J--J--1--L--L--1---1--J--1- '=�VX a I 1 1 1 1 I I 1 1 1 1 1 1 1 1 I I 1 1 1 1 --L--'--J--,--1--1--L--L--'---'--J -----1--L--L--1---1--J--1--1--1--L-- 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3 I 1 1 1 1 I I I I I I 1 1 1 1 I I 1 1 1 1 2 I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) ■ Runoff ACSA Detention - A01 Type/1 24-hr 1 YEAR Rainfall=3.04" Prepared by Dewberry- Richmond Office Printed 9/9/2022 Summary for Subcatchment 6S: Bypass A01 Runoff = 1.48 cfs @ 12.00 hrs, Volume= 0.074 af, Depth> 0.78" Routed to Reach 1 R : AO Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type II 24-hr 1 YEAR Rainfall=3.04" Area (ac) CN Descriotion " 0.840 61 Managed Turf- Onsite " 0.300 98 Impervious - Onsite 1.140 71 Weighted Average 0.840 73.68% Pervious Area 0.300 26.32% Impervious Area Tc Length 7.0 1 Description Direct Entry, Subcatchment 6S: Bypass A01 Hydrograph i i I I i i I I i i I I I I I I I I i i i i i i I I I I I I r 4 ---- I Time (houm) i i I I I i i I I I I i i I I I i i I I I I i i I I I i i I I I I Type II'124-hr 1 YEAR RainfallT3.04 Rwnbff Areti=1.140 at: I I I � � I I I I R-Lp'ngff',VpCome=,`OVT Cf kunoff bipih>0.78�' �I,I,I,��IIII Tc=7.0 nib I I I CAN=7!1 ■ Runoft ACSA Detention - A01 Prepared by Dewberrv- Richmond Office Type 11 24-hr 1 YEAR Rainfall=3.04" Printed 9/9/2022 Summary for Reach 1 R: A01 Inflow Area = 7.510 ac, 43.94% Impervious, Inflow Depth > 0.52" for 1 YEAR event Inflow = 1.67 cfs @ 12.00 hrs, Volume= 0.327 of Outflow = 1.57 cfs @ 12.02 hrs, Volume= 0.325 af, Atten= 6%, Lag= 1.7 min Routed to nonexistent node 2R Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Max. Velocity= 0.67 fps, Min. Travel Time= 2.8 min Avg. Velocity = 0.47 fps, Avg. Travel Time= 4.0 min Peak Storage= 262 cf @ 12.02 hrs Average Depth at Peak Storage= 0.16' , Surface Width= 14.89' Bank -Full Depth= 10.00' Flow Area= 415.0 sf, Capacity= 2,916.59 cfs 14.00' x 10.00' deep channel, n= 0.050 Earth, long dense weeds Side Slope Z-value= 2.5 3.0 7' Top Width= 69.00' Length= 111.6' Slope= 0.0055 7' Inlet Invert= 504.58', Outlet Invert= 503.97' Reach 1 R: A01 Hydrograph , 67 ck Inflow Area=7,.516 ac Avg. Flown DepthTO.'16' Max Vel=0.67 fps n=0.050 S=0i0©55 T Capacity=2'91 G.6a9 Ccfs Ili011iFR F1011iiiiiiiiiiiiiiiiiiiiiiiiii3i ■ Inflow ❑ OWlow ACSA Detention - A01 Prepared by Dewberrv- Richmond Office Type 11 24-hr 1 YEAR Rainfall=3.04" Summary for Pond 1P: SWM1 Printed 9/9/2022 Inflow Area = 6.370 ac, 47.10% Impervious, Inflow Depth > 1.18" for 1 YEAR event Inflow = 13.09 cfs @ 11.98 hrs, Volume= 0.629 of Outflow = 0.25 cfs @ 17.94 hrs, Volume= 0.252 af, Atten= 98%, Lag= 357.5 min Primary = 0.25 cfs @ 17.94 hrs, Volume= 0.252 of Routed to Reach 1 R : A01 Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Peak Elev= 524.22' @ 17.94 hrs Surf.Area= 0.129 ac Storage= 0.408 of Plug -Flow detention time= 356.4 min calculated for 0.252 of (40% of inflow) Center -of -Mass det. time= 223.1 min ( 1,068.6 - 845.5 ) Volume Invert Avail.Storage Storage Description #1 518.50' 1.583 of Custom Stage Data (Prismatic)Listed below Elevation Surf.Area Inc.Store Cum.Store (feet) (acres) (acre-feet) (acre-feet) 518.50 0.000 0.000 0.000 519.00 0.031 0.008 0.008 520.00 0.046 0.038 0.046 521.00 0.063 0.054 0.101 522.00 0.082 0.073 0.173 523.00 0.102 0.092 0.265 524.00 0.124 0.113 0.378 525.00 0.147 0.135 0.514 526.00 0.172 0.159 0.673 527.00 0.198 0.185 0.858 528.00 0.226 0.212 1.070 529.00 0.256 0.241 1.311 530.00 0.287 0.272 1.583 Device Routing Invert Outlet Devices #1 Primary 518.50' 30.0" Round Culvert L= 102.0' RCP, groove end projecting, Ke= 0.200 Inlet / Outlet Invert= 518.50' / 515.00' S= 0.0343 '/' Cc= 0.900 n= 0.013, Flow Area= 4.91 sf #2 Device 1 518.50' 2.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Device 1 525.90' 16.0" W x 12.0" H Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #4 Device 1 526.90' 60.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=0.25 cfs @ 17.94 hrs HW=524.22' TW=504.62' (Dynamic Tailwater) t1=Culvert (Passes 0.25 cfs of 62.46 cfs potential flow) 2=Orifice/Grate (Orifice Controls 0.25 cfs @ 11.43 fps) 3=Orifice/Grate ( Controls 0.00 cfs) =Orifice/Grate ( Controls 0.00 cfs) ACSA Detention - A01 Prepared by Dewberry- Richmond Office Type // 24-hr 1 YEAR Rainfall=3.04" Printed 9/9/2022 Pond IP: SWM7 Hydrograph / I 14 '�■Pnmary 13 -i-- iiii ii -��IOIW}/1rp�V.IQaV- I I I I I I I I _ II 12, -Storage=I 0�40& a#- ,6 �' __I __l__7__r__i__�__r__ 9 -rr 7_r__rJJ --r- _ 1 1 I I I I I I I I I _1 _L _I _J _1_L _I _J _J _L _I _J _1 _L_J _J _1 _L _L_J a I I I I I I I I I I I I / I I I I I I O7-r T -I -7 -r T-1 -1 -r T-1 -T -r -I -1 -T -r -r -I _L _I__J _1 _L_ I__J _1 _L _L_J 6 I I I I I I I I I I I I I / 4 I I I I I I I I I I I I I I 3- 2- 4 5 6 7 8 9 10 11 12 13 Time (hours) ACSA Detention - A01 Prepared by Dewberry- Richmond Office Type 11 24-hr 10 YEAR Rainfall=5.56" Printed 9/9/2022 Summary for Subcatchment 1S: Existing DA Runoff = 9.68 cfs @ 12.10 hrs, Volume= 0.709 af, Depth> 1.33" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type II 24-hr 10 YEAR Rainfall=5.56" Area (ac) CN Descriotion " 0.310 61 Managed Turf- B " 5.950 55 Wooded - B " 0.110 98 Impervious 6.370 56 Weighted Average 6.260 98.27% Pervious Area 0.110 1.73% Impervious Area Tc Length Slope Velocity Capacity Description 15.8 Direct Entry, Subcatchment 1S: Existing DA Hydrograph I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I 10 I I I I I I I I I I ef�G16 I I I I I I I I I I I J� I I I I I I I I I I I I I I I I _*�i1�o-'�-��klf- 9 TI 1A-YEARRainfalll I I I � I I I I I I I I I I - iI�. n -7 -YI -T -Y -Y -I -I -YI -Y -Y -Y -Y a/ I I I I I I I I I _ RuhGff_Ar6z=f:370_ba':- I I I I I I I I I I I I I I I I I I I I I I 7 _RuoF�/ourn_I 0 7 9l a• --+- - --I--+ -;--+--+--~---------+--+--+--~-- 6 ' Fkunoff be' tft>C. 310 __r__r__r__i___I__r _4__1__7__r__I __I__,__ r__r__r__r__ 5 Tc-15.8 min: LL I I I I I I I I I I I I I I I 4 N=5, I I I I I I I I I I I I I I I 3 I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I 2, I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I 1 i I I I I i i I I I I I I I I 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) ■ Runoff ACSA Detention - AO1 Prepared by Dewberrv- Richmond Office Type II 24-hr 10 YEAR Rainfall=5.56" Printed 9/9/2022 Summary for Subcatchment 2S: Existing Offsite AO1 Runoff = 6.47 cfs @ 11.96 hrs, Volume= 0.290 af, Depth> 2.63" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type II 24-hr 10 YEAR Rainfall=5.56" Area (ac) CN Description 0.650 61 Managed Turf- B 0.240 55 Wooded - B 0.430 98 Impervious 1.320 72 Weighted Average 0.890 67.42% Pervious Area 0.430 32.58% Impervious Area Tc Length Slope Velocity Capacity Description 5.0 1 Direct Entry, Subcatchment 2S: Existing Offsite AO1 Hydrograph I I I I I I I I I I I I I I I I C I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I i i I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I i I I I I I I I I I I I I I I I I I I I I I I I I I I I I i I I I I Type If 24-hr 10 YEAR RainfallT5.56" -----Runoff Area=7:320 ac RungfflllVolume=,,0.290 of Runoff Depth>2.63" Tc=5.1110 min . QN=72 I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I 9 1 2 3 4 5 6 7 8 9 19 11 12 13 14 15 16 17 18 19 29 21 22 23 24 Time (hours) ❑ Runoff ACSA Detention - AO1 Prepared by Dewberrv- Richmond Office Type II 24-hr 10 YEAR Rainfall=5.56" Printed 9/9/2022 Summary for Subcatchment 3S: Forested Runoff = 5.25 cfs @ 12.37 hrs, Volume= 0.666 af, Depth> 1.25" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type II 24-hr 10 YEAR Rainfall=5.56" Area (ac) CN Description 6.370 55 Wooded - B 6.370 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 34.9 Direct Entry, Subcatchment 3S: Forested Hydrograph 5 Type II 24-hr 10 YEAR Rainfall=5.56" 4 Runoff Area=6.370 ac Runoff Volume=0.666 of 3 Runoff Depth>1.25" Tc=34.9 min CN=55 1 9 1 2 3 4 5 6 7 8 9 19 11 12 13 14 15 16 17 18 19 29 21 22 23 24 Time (hours) ❑ Runoff ACSA Detention - AO1 Prepared by Dewberry- Richmond Office Type 11 24-hr 10 YEAR Rainfall=5.56" Printed 9/9/2022 Summary for Subcatchment 4S: Mite AO1 Runoff = 6.47 cfs @ 11.96 hrs, Volume= 0.290 af, Depth> 2.63" Routed to Pond 1 P : SWM1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type II 24-hr 10 YEAR Rainfall=5.56" Area (ac) CN Description " 0.650 61 Managed Turf- B " 0.240 55 Wooded - B " 0.430 98 Impervious 1.320 72 Weighted Average 0.890 67.42% Pervious Area 0.430 32.58% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Subcatchment 4S: Offsite AO1 Hydrograph 7 ■Runoff 4 3 � 2 11 12 13 Time (hours) 16 *EAR RaWallT5.56" un-b Fe�= ai- ft4n_gff- V410me=%290 elf r , rF,tiU7.1WX1111M] CAN=72 ACSA Detention - A01 Prepared by Dewberry- Richmond Office Type 11 24-hr 10 YEAR Rainfall=5.56" Summary for Subcatchment 5S: Proposed SWM A01 Runoff = 28.98 cfs @ 11.98 hrs, Volume= 1.423 af, Depth> 3.38" Routed to Pond 1 P : SWM1 Printed 9/9/2022 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type II 24-hr 10 YEAR Rainfall=5.56" Area (acl CN Descriotion " 2.480 61 Managed Turf- Onsite " 2.570 98 Impervious - Onsite 5.050 80 Weighted Average 2.480 49.11 % Pervious Area 2.570 50.89% Impervious Area Tc Length Description 7.0 Direct Entry, Subcatchment 5S: Proposed SWM A01 Hydrograph 32 --------- -- -- -- -------------- -- -- --------- -- -- -- -- -- 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 --r--r-r--r--r--r --r --r 1 1--r--r--r--r-- 30 1 1 1 1 1 1 1 28.98 cfa 1 1 1 1 1 1 1 1 28 __ I_ 1 1 1 1 I I 1 1 1 __________________________ 1------1---1- 11---11---1� ��-- ---"-- - 26 I 1 1 1 1 I I 1 1 1 I 1 1 1 1 I I 1 1 1 1 r 1 -, -, -, -r- r r 1 1 -, -, �o- EARRatnfall;;& ' 24 , 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I I_ I_ J__1_ L_ L_ L_ I_ I_ I LRdnbfF-Aret=5.050 - 22 I I I I I I I I I I I I at: 1 I 26 ' --;--1--r--r--r--;--; --, --1, --1--;--'R4nOff�V'_I 'm�e=1.�42-a�f - ury� 18 1 1 1 1 1 1 1 --I----- -- ------ --------- -- 1 ----+-A1uno#:D0ih> �S�'-- 1 1 1 1 1 1 1 3 16 o ' I 1 1 1 1 I I 1 1 1 1 I 1 1 1 1 I tI 1 1 1 1 __r__�__r__r__'__T__r__r__r__�__� __*--T--r--r-----I- r - -0 fi�_- 1 1 1 1 1 1 1 1 1 1 1 1 T 1 1 n 14 L__1--J--,--1--1--L--L--1---1--J 12 - --1--1--L--L--1---1--J--1--1--L--L-- 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I 1 1 1 1 1 1 I 1 1 I I 10 1 1 1 1 1 1 1 1 1 1 1 1 1 1 8 ___---- _I__I__I__I__I__I___I___I___I g, I 1 1 1 1 I I 1 1 1 1 I 1 1 1 1 I I 1 1 1 1 --r-1--r--r--r--r--r--r--1r--r-�_-r-r-r-r--I--l--r--T--r--r-_ 4' 1 1 1 1 1 1 1 1 1 1 1 I 1 1 1 1 ___I__J__J__1__L__L__ 2 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 Time (hours) ■ Runoff ACSA Detention - A01 Type 11 24-hr 10 YEAR Rainfall=5.56" Prepared by Dewberry- Richmond Office Printed 9/9/2022 Summary for Subcatchment 6S: Bypass A01 Runoff = 5.01 cfs @ 11.99 hrs, Volume= 0.242 af, Depth> 2.54" Routed to Reach 1 R : AO Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type II 24-hr 10 YEAR Rainfall=5.56" Area (ac) CN Description " 0.840 61 Managed Turf- Onsite " 0.300 98 Impervious - Onsite 1.140 71 Weighted Average 0.840 73.68% Pervious Area 0.300 26.32% Impervious Area Tc Length 7.0 Description Direct Entry, Subcatchment 6S: Bypass A01 Hydrograph I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I Z I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I i I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I II II II II I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I TYpg I I I I I I I I I 10 YEAR RainfallT5.56 Runbff Areti=1.140 arc I I I I I I I I I I I R0ngff'I Vg10me='10.242 elf btunoff DepfW -54i" I I I I I I I I I I I Tc=7.0 libih " T C0IY 7K I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I - r--r --r--r I I I I I I I I 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) ■ Runoff ACSA Detention - A01 Prepared by Dewberry- Richmond Office Type 11 24-hr 10 YEAR Rainfall=5.56" Summary for Reach 1R: A01 Printed 9/9/2022 Inflow Area = 7.510 ac, 43.94% Impervious, Inflow Depth > 2.06" for 10 YEAR event Inflow = 5.62 cfs @ 12.24 hrs, Volume= 1.286 of Outflow = 5.61 cfs @ 12.25 hrs, Volume= 1.284 af, Atten= 0%, Lag= 1.0 min Routed to nonexistent node 2R Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Max. Velocity= 1.06 fps, Min. Travel Time= 1.8 min Avg. Velocity = 0.54 fps, Avg. Travel Time= 3.4 min Peak Storage= 591 cf @ 12.25 hrs Average Depth at Peak Storage= 0.35' , Surface Width= 15.94' Bank -Full Depth= 10.00' Flow Area= 415.0 sf, Capacity= 2,916.59 cfs 14.00' x 10.00' deep channel, n= 0.050 Earth, long dense weeds Side Slope Z-value= 2.5 3.0 7' Top Width= 69.00' Length= 111.6' Slope= 0.0055'/' Inlet Invert= 504.58', Outlet Invert= 503.97' • • 1 Avo.:Flow De N • ,I I 1 N 1 N 1 . • . ,, 4 5 6 7 3 9 10 11 12 13 Time (hour) ■ Inflow ■ outlimll ACSA Detention - A01 Prepared by Dewberrv- Richmond Office Type II 24-hr 10 YEAR Rainfall=5.56" Summary for Pond 1P: SWM1 Printed 9/9/2022 Inflow Area = 6.370 ac, 47.10% Impervious, Inflow Depth > 3.23" for 10 YEAR event Inflow = 35.24 cfs @ 11.98 hrs, Volume= 1.713 of Outflow = 4.86 cfs @ 12.26 hrs, Volume= 1.045 af, Atten= 86%, Lag= 16.9 min Primary = 4.86 cfs @ 12.26 hrs, Volume= 1.045 of Routed to Reach 1 R : A01 Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Peak Elev= 526.92' @ 12.26 hrs Surf.Area= 0.196 ac Storage= 0.844 of Plug -Flow detention time= 209.2 min calculated for 1.045 of (61% of inflow) Center -of -Mass det. time= 99.5 min ( 916.6 - 817.2 ) Volume Invert Avail.Storage Storage Description #1 518.50' 1.583 of Custom Stage Data (Prismatic)Listed below Elevation Surf.Area Inc.Store Cum.Store (feet) (acres) (acre-feet) (acre-feet) 518.50 0.000 0.000 0.000 519.00 0.031 0.008 0.008 520.00 0.046 0.038 0.046 521.00 0.063 0.054 0.101 522.00 0.082 0.073 0.173 523.00 0.102 0.092 0.265 524.00 0.124 0.113 0.378 525.00 0.147 0.135 0.514 526.00 0.172 0.159 0.673 527.00 0.198 0.185 0.858 528.00 0.226 0.212 1.070 529.00 0.256 0.241 1.311 530.00 0.287 0.272 1.583 Device Routing Invert Outlet Devices #1 Primary 518.50' 30.0" Round Culvert L= 102.0' RCP, groove end projecting, Ke= 0.200 Inlet / Outlet Invert= 518.50' / 515.00' S= 0.0343 '/' Cc= 0.900 n= 0.013, Flow Area= 4.91 sf #2 Device 1 518.50' 2.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Device 1 525.90' 16.0" W x 12.0" H Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #4 Device 1 526.90' 60.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=4.86 cfs @ 12.26 hrs HW=526.92' TW=504.93' (Dynamic Tailwater) t1=Culvert (Passes 4.86 cfs of 79.11 cfs potential flow) 2=Orifice/Grate (Orifice Controls 0.30 cfs @ 13.90 fps) 3=Orifice/Grate (Orifice Controls 4.40 cfs @ 3.30 fps) =Orifice/Grate (Weir Controls 0.15 cfs @ 0.47 fps) ACSA Detention - A01 Prepared by Dewberry- Richmond Office Type ll 24-hr 10 YEAR Rainfall=5.56" Printed 9/9/2022 Pond IP: SWM7 Hydrograph _ _J -1 _-1 -F -F_ ■Inflow __ __�__,_ '--�--'--"__---'------"--i------'-- ■Prima ry 38 I 35.za GB I I I I -r 36 ,' I - n lt�vvWe �6;3701a�- 34 I I I --I--�--r--r--r--r-,--r--r-�--� --r - - I r r r- 32 30 r 1 1 1 1 1 1 1 1 1 1 1 Iy� Ih IIQj 28 \Id�a\}jr ` A�$j{I �i�IIiLII� L__I__SbDrA"T�Y'S4taf- 26 24 •' _{ _F_J .@ 22 _I -4 -F _I _I _4 -1 _I _� _I 26 3 , - -7 -Y -Y -I -I -Y -Y -I --I -y -r -I -7 -T -Y -I -� 0 18 __-__r__r__r__I__ 16 14 12 ___________________----- ___ __________________________ 10 6 4.W�y 4 5 6 7 8 9 10 11 12 13 Time (hours) Avon Maintenance Yard Albemarle County Dewberry Water Resources Engineering STEP 1: Determine the Pre Develope Pre Developed Conditions Weighhd CN= 56.7 Area (ac) = 6.66 P(in.)= 3.04 STEP 2: Determine the peak dischim Pre Developed Discharge S 7.6 In 1.5 Q(in) 03 in Volume 0.139 ac-ft Forested, and Post Develope Forested Conditions Weighted CN= 55.4 Area (ac) = 6.66 P(in.)= 3.04 Forested Conditions Discharge S 8.1 Is 1.6 Q(in) 0.2 in Volume 0. 120 ac-ft Total Forested Peak Discharge 0.36 cfs value using Runoff Reduction provided in BMPs BMP Runoff fts fls to to OutW1 A03 Charmel Type: NatuM within the disturbed area Post Developed Conditions N1 righted CN = 78.3 Area (ac)= 6.67 P(in.)= 3.04 Post Development Discharge S 2.8 Is 0.6 Q (in) 1.2 in Volume 0.653 ac-ft Total Predevelopment Discharge Qpost without RR = Qpost with RR= Adjusted CN = Engineer: SPC Clacker: HCG 0.93 cfs 12 12 78 Total = 0 ft STEP 4: Calculate Caa ,.,ue using the energy balance equation. Only apply the improvement factor to the disturbed area. Energy Balance Equation: Q, S lEx(Q1u,, ,,x RVere-Dne.,) / RVo,, Improvement Factor 0.8 Qsa, 5 [Total Predevelopment Discharge (Offsite Volume +(Improvement Factor x Pre -Developed Volume) / (Post -Development Volume +011site Volume)] Qsa—. R16 cfs STEP 5: Calculated Maximum Allowable Peak Discharge. mum Allowable Peak Discharge = Maximum (Q� , Qsiw ,,), never greater than Total PreDevelopment Discharge = Total Forest Peak Discharge x (Forest Volume + Offsite Volume)I(Post-Development Volume +Offsite Volume) 0.07 cfs cable Site Area Discharge + OfFsite Area Peak Discharge - Detained = gy Balance) 0.16 cfs 2.06 cfs Allowable 2.22 cfs .i.—a is less than the Maximum Allowable Peak 2.18 cfs Adequate O\'I5S OfFsite AO� Prop eCSWMA07 \ 1P 6S 7S aS 1S 2S 3S swMf\% B ass AO7 ORsil"03 Pr seU SWM A03 Existing DA Existing Ogsite A03 Forested 1R 2P AO7 \ ISWM2 \27 2R 1 1 9S A03 Bypass A03 Subcat Reach Aon Llnk ACSA Detention - AO3 Prepared by Dewberrv- Richmond Office Rainfall Events Listing (selected events) Event# Event Storm Type Curve Mode Duration B/B Depth AMC Name (hours) (inches) 1 1 YEAR Type II 24-hr Default 24.00 1 3.04 2 2 10 YEAR Type II 24-hr Default 24.00 1 5.56 2 Printed 9/9/2022 ACSA Detention - AO3 Prepared by Dewberrv- Richmond Office Type 11 24-hr 1 YEAR Rainfall=3.04" Printed 9/9/2022 Summary for Subcatchment 1S: Existing DA Runoff = 0.93 cfs @ 12.15 hrs, Volume= 0.142 af, Depth> 0.26" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type II 24-hr 1 YEAR Rainfall=3.04" Area (ac) CN Description 0.380 61 Managed Turf- B 6.030 55 Wooded - B 0.140 98 Impervious 0.110 80 Managed Turf- D 6.660 57 Weighted Average 6.520 97.90% Pervious Area 0.140 2.10% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 15.8 Direct Entry, Subcatchment 1S: Existing DA Hydrograph ' ' ' ' ' ' ' ■Runoff Type II 24-hr 1 YEAR Rainfall=3.04" Runoff Area=6.660 ac Runoff Volume=0.142 of Runoff Depth>0.26" Tc=15.8 min CN=57 0 9 1 2 3 4 5 6 7 8 9 19 11 12 13 14 15 16 17 Time (hours) ACSA Detention - AO3 Prepared by Dewberrv- Richmond Office Type 11 24-hr 1 YEAR Rainfall=3.04" Printed 9/9/2022 Summary for Subcatchment 2S: Existing Offsite AO3 Runoff = 2.06 cfs @ 11.97 hrs, Volume= 0.094 af, Depth> 0.83" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type II 24-hr 1 YEAR Rainfall=3.04" Area (ac) CN Description 0.690 61 Managed Turf- B 0.240 55 Wooded - B 0.430 98 Impervious 1.360 72 Weighted Average 0.930 68.38% Pervious Area 0.430 31.62% Impervious Area Tc Length Slope Velocity Capacity Description I—i-\ If --A /f1/f1\ /H/oo..\ /.do\ 5.0 Direct Entry, Subcatchment 2S: Existing Offsite AO3 Hydrograph ❑ Runoff 2 Type II 24-hr 1 YEAR Rainfall=3.04" Runoff Area=1.360 ac Runoff Volume=0.094 of LL 1 I I Runoff Depth>0.83" Tc=5.0 min CN=72 9 1 2 3 4 5 6 7 8 9 19 11 12 13 14 15 16 17 18 19 29 21 22 23 24 Time (hours) ACSA Detention - AO3 Prepared by Dewberrv- Richmond Office Type 11 24-hr 1 YEAR Rainfall=3.04" Summary for Subcatchment 3S: Forested Runoff = 0.36 cfs @ 12.53 hrs, Volume= 0.111 af, Depth> 0.20" Printed 9/9/2022 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type II 24-hr 1 YEAR Rainfall=3.04" Area (ac) CN Description ' 6.540 55 Wooded - B ' 0.120 77 Wooded - D 6.660 55 Weighted Average 6.660 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 34.9 Direct Entry, Subcatchment 3S: Forested Hydrograph '1 o.a ' --1 ---tI --r--r--1--r--+--�--r--1---1-- r 1 r -r 1 0.38 1 I -, -, -r -r -I -, -, -+ - 0.36 Cs -I -, -, -r -r -I I -I -, -r 1 -r -I 0.36 it/ p--I--,--,--T--r- e ;1114 1 1 -�/ -I--,--, --T--r --I---I--,--T--T--I-- I 0.34 0.32 _i__=� �!-- 1 YEAR Rainfall=3.04" Ir- --;--;--r--Ir--I, -- 11--T--r--I, - 0.3 �' RLunQffArea=6.6fi0_ac _ 0.28 i 1 1 1 1'11-Runoff -------------------------- 0.26-' g1urnq--0r ,1faf N 022 I I I III I ` I/� I�/� I 1i -Runoff > IIVZV1'--+--I11 I I I I I I I I I I I 1 --I-- 3 0'2 Ie�G - 1--1--J--1--L----1--1----i--�- - 1--1--1-----1 --1--1--L--1------i--L--1-- 1 1--1 018 1 �y�9 rhinl +--1--J----i--�- �__�--1--L--1-- LL --1 -1--1--L--1-- .1 O.,a O 12 --1---I1--�--'--r--r--1--r--�--�--r --1----- --1---II--�--+--r--1-- -I 0.081 1 0.06 11 , -T -r -r -I -, -, -T- r -I -1 -T -T- r- I 0.04 I -T -- -r -I -T -, -T-T -T -I 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Time (hours) ❑ Runoff ACSA Detention - AO3 Prepared by Dewberry- Richmond Office Type/1 24-hr 1 YEAR Rainfall=3.04" Summary for Subcatchment 4S: Mite AO1 Runoff = 2.00 cfs @ 11.97 hrs, Volume= 0.091 af, Depth> 0.83" Routed to Pond 1 P : SWM1 Printed 9/9/2022 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type II 24-hr 1 YEAR Rainfall=3.04" Area (ac) CN Descriotion " 0.650 61 Managed Turf- B " 0.240 55 Wooded - B " 0.430 98 Impervious 1.320 72 Weighted Average 0.890 67.42% Pervious Area 0.430 32.58% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Subcatchment 4S: Offsite AO1 Hydrograph i z.00�--r__r__r _-ir__7__T__r__r 2 " .Type 11'1 24-h�r 1 DEAR Rai6fallT3.04" Rwnbff Areh=1.320 at: Rll#ngff', V910me=,0.09�,1 4f Runoff Depth>0.83"' G - Tai 5.;01trtilh CAN=72 11 12 13 Time (hours) ■ Runoff ACSA Detention - A03 Prepared by Dewberry- Richmond Office Type/1 24-hr 1 YEAR Rainfall=3.04" Summary for Subcatchment 5S: Proposed SWM A01 Runoff = 11.16 cfs @ 11.99 hrs, Volume= 0.538 af, Depth> 1.28" Routed to Pond 1 P : SWM1 Printed 9/9/2022 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type II 24-hr 1 YEAR Rainfall=3.04" Area facl CN Descriotion " 2.480 61 Managed Turf- Onsite " 2.570 98 Impervious - Onsite 5.050 80 Weighted Average 2.480 49.11 % Pervious Area 2.570 50.89% Impervious Area Tc Length Description 7.0 Direct Entry, Subcatchment 5S: Proposed SWM A01 Hydrograph _l__L__ L__L__I___I__J__J__1__L__L__ 12 I I I I I I I I I I I I I I I I I I I I I I I --�---�--�--�--�--�--L--�---'--L_ 11.1ficfa-J--L--L--'---'--J--J--L--�--L--'- „ -- -- -- -- -- -- ----- - - -- -- TypQ_1I'124-Mr - 10 1 YEAR Rainfall=*.OW I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I 9 'Rwnbff Areti=5.050 at: 1 1 --r--1--7--7--7--T--r--r--I --1--, --T--T--T--r--I 8- ' - ; Wnpff��V_plylme_=,'0.$3$-elf_- __�___ __�__ 7__ T__ �__ r__ �___�__1 ___i___i__y__t__r__r__r__i___i__.� k noffboih>l_28k O 6' 1 1 1 1 1 1 1 1 1 1 1 1 /� 1 7 1 y1m- 1y^ 1 1 1 1 1 1 1 1 1 1 1 1 TaI�t�-Mirlk- 1L I I I I I I I I I I I I I I I I I I I I I I --L--1--J--J--1--1--L--L--1---1--J--J--1--L--L--1---1--J--1- '=�VX a I 1 1 1 1 I I 1 1 1 1 1 1 1 1 I I 1 1 1 1 --L--'--J--,--1--1--L--L--'---'--J -----1--L--L--1---1--J--1--1--1--L-- 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3 I 1 1 1 1 I I I I I I 1 1 1 1 I I 1 1 1 1 2 I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) ■ Runoff ACSA Detention - A03 Type/1 24-hr 1 YEAR Rainfall=3.04" Prepared by Dewberry- Richmond Office Printed 9/9/2022 Summary for Subcatchment 6S: Bypass A01 Runoff = 1.48 cfs @ 12.00 hrs, Volume= 0.074 af, Depth> 0.78" Routed to Reach 1 R : AO Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type II 24-hr 1 YEAR Rainfall=3.04" Area (ac) CN Descriotion " 0.840 61 Managed Turf- Onsite " 0.300 98 Impervious - Onsite 1.140 71 Weighted Average 0.840 73.68% Pervious Area 0.300 26.32% Impervious Area Tc Length 7.0 1 Description Direct Entry, Subcatchment 6S: Bypass A01 Hydrograph i i I I i i I I i i I I I I I I I I i i i i i i I I I I I I r 4 ---- I Time (houm) i i I I I i i I I I I i i I I I i i I I I I i i I I I i i I I I I Type II'124-hr 1 YEAR RainfallT3.04 Rwnbff Areti=1.140 at: I I I � � I I I I R-Lp'ngff',VpCome=,`OVT Cf kunoff bipih>0.78�' �I,I,I,��IIII Tc=7.0 nib I I I CAN=7!1 ■ Runoft ACSA Detention - A03 Prepared by Dewberrv- Richmond Office Type 11 24-hr 1 YEAR Rainfall=3.04" Summary for Subcatchment 7S: Offsite A03 Runoff = 0.02 cfs @ 11.99 hrs, Volume= 0.001 af, Depth> 0.38" Routed to Pond 2P : SWM2 Printed 9/9/2022 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type II 24-hr 1 YEAR Rainfall=3.04" Area (ac) CN Description 0.040 61 Managed Turf- B 0.040 100.00% Pervious Area Tc Length Slope Velocity Capacity Description 5.0 Direct Entry, Subcatchment 7S: Offsite A03 Hydrograph _---�i--T 0.024 ----------T--f---- ,--------}--i- - I 0.023 0.02 Cfe 0.022 --I--,--r--r--r--I--,--'I--r--r r--r' 0.021 -----1--1-----J--1--L--'-- � II � Syr.__ -_L-- Type 'rr-- 0.02 ------'--`-------'----�-- 1, YEAR a�li"1 lA_ 0.019 7 1 T _ygJ—_L" -,' -r-r-r-I-,-r- Runoff Area=0.-040a& - 0.015 R-unQu�lump=p.00 I 0.014 ,-- r--r- - - -- �EREa�i�nf --r--r-_1_____hL__L_ 0.009 I I I I I I I I I 0.00s - -- _ 0.004 —- r- ---- - r--r--�---�--r-r--r �--,--�--r-- 9.993 I I I I I I I I I I I I I I I I I—�--�--}-- 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) ❑ Runoff ACSA Detention - AO3 Prepared by Dewberrv- Richmond Office Type 11 24-hr 1 YEAR Rainfall=3.04" Printed 9/9/2022 Summary for Subcatchment 8S: Proposed SWM AO3 Runoff = 0.62 cfs @ 11.97 hrs, Volume= 0.028 af, Depth> 1.16" Routed to Pond 2P : SWM2 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type II 24-hr 1 YEAR Rainfall=3.04" Area (ac) CN Description ' 0.160 61 ' 0.130 98 0.290 78 Weighted Average 0.160 55.17% Pervious Area 0.130 44.83% Impervious Area Tc Length Slope Velocity Capacity Description 5.0 0.1 Direct Entry, Subcatchment 8S: Proposed SWM AO3 Hydrograph C I I I _L- I - L------J I I I --J - - I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I -I -T -f I I I I I I I I I I I I I I I I I I I I I I I 1 1 I I I I I I I I I I I I I I I I I I I I I I I I I I I I - -y -y I -y I -Y I -r -I I I I I I Type II 24-hr 1 YEAR Rainfa11:;3.04" Runoff Area=9.290Ta1�_ Runoff Vo1gm0=4.02$-0f- --III Runoff IlDepth>1:9f1'- Tc=5.0 mih- I I I I I ----------------------------- I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) ❑ Runoff ACSA Detention - A03 Prepared by Dewberrv- Richmond Office Type 11 24-hr 1 YEAR Rainfall=3.04" Printed 9/9/2022 Summary for Subcatchment 9S: Bypass A03 Runoff = 0.54 cfs @ 11.96 hrs, Volume= 0.024 af, Depth> 1.55" Routed to Reach 2R : A03 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type II 24-hr 1 YEAR Rainfall=3.04" Area (ac) CN Description ' 0.040 61 Managed Turf- B ' 0.080 98 Impervious ' 0.070 80 Managed Turf- D 0.190 84 Weighted Average 0.110 57.89% Pervious Area 0.080 42.11% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Subcatchment 9S: Bypass A03 Hydrograph 0.6 I I I I I I I I I 0.55 I I I I I I I I I 1 0.5 I I I I I I I I I 1 0.45 I 0.4 0.35 III N -------------------------- - 0.3 I I I I c LL I I I I I I I I I I I I 0.25 I I I I I I I I I I I 0 2 I I 0.15 i i i i i I I I I I 0.1 I I I I I I I I Time (horns) 17 u112q-pr- 7-SEA' R-Ra➢nfa11;;1G4"- Runbff'JAkeA=a A9d at I I I I I #runoff V00m0=o=424-0# -----Runoff# 111Deptl4:"' I I I I I I I I I I I --- I I I I I I I I I I I I 1 I I I I I I I I I I I I I I I I I I I I I I I I I I I 1 ❑ Runoff ACSA Detention - A03 Prepared by Dewberrv- Richmond Office Type 11 24-hr 1 YEAR Rainfall=3.04" Printed 9/9/2022 Summary for Reach 1 R: A01 Inflow Area = 7.510 ac, 43.94% Impervious, Inflow Depth > 0.52" for 1 YEAR event Inflow = 1.67 cfs @ 12.00 hrs, Volume= 0.327 of Outflow = 1.57 cfs @ 12.02 hrs, Volume= 0.325 af, Atten= 6%, Lag= 1.7 min Routed to Reach 2R : A03 Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Max. Velocity= 0.67 fps, Min. Travel Time= 2.8 min Avg. Velocity = 0.47 fps, Avg. Travel Time= 4.0 min Peak Storage= 262 cf @ 12.02 hrs Average Depth at Peak Storage= 0.16' , Surface Width= 14.89' Bank -Full Depth= 10.00' Flow Area= 415.0 sf, Capacity= 2,916.59 cfs 14.00' x 10.00' deep channel, n= 0.050 Earth, long dense weeds Side Slope Z-value= 2.5 3.0 7' Top Width= 69.00' Length= 111.6' Slope= 0.0055 7' Inlet Invert= 504.58', Outlet Invert= 503.97' Reach 1 R: A01 Hydrograph , 67 ck Inflow Area=7,.516 ac Avg. Flown DepthTO.'16' Max Vel=0.67 fps n=0.050 S=0i0©55 T Capacity=2'91 G.6a9 Ccfs Ili011iFR F1011iiiiiiiiiiiiiiiiiiiiiiiiii3i ■ Inflow ❑ OWlow ACSA Detention - A03 Prepared by Dewberrv- Richmond Office Type 11 24-hr 1 YEAR Rainfall=3.04" Printed 9/9/2022 Summary for Reach 2R: A03 Inflow Area = 8.030 ac, 43.71 % Impervious, Inflow Depth > 0.57" for 1 YEAR event Inflow = 2.18 cfs @ 12.01 hrs, Volume= 0.379 of Outflow = 2.18 cfs @ 12.01 hrs, Volume= 0.379 af, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Reach 2R: A03 Hydrograph ❑ InHow ❑ Outflow Time (hours) ACSA Detention - A03 Prepared by Dewberrv- Richmond Office Type 11 24-hr 1 YEAR Rainfall=3.04" Summary for Pond 1P: SWM1 Printed 9/9/2022 Inflow Area = 6.370 ac, 47.10% Impervious, Inflow Depth > 1.18" for 1 YEAR event Inflow = 13.09 cfs @ 11.98 hrs, Volume= 0.629 of Outflow = 0.25 cfs @ 17.94 hrs, Volume= 0.252 af, Atten= 98%, Lag= 357.5 min Primary = 0.25 cfs @ 17.94 hrs, Volume= 0.252 of Routed to Reach 1 R : A01 Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Peak Elev= 524.22' @ 17.94 hrs Surf.Area= 0.129 ac Storage= 0.408 of Plug -Flow detention time= 356.4 min calculated for 0.252 of (40% of inflow) Center -of -Mass det. time= 223.1 min ( 1,068.6 - 845.5 ) Volume Invert Avail.Storage Storage Description #1 518.50' 1.583 of Custom Stage Data (Prismatic)Listed below Elevation Surf.Area Inc.Store Cum.Store (feet) (acres) (acre-feet) (acre-feet) 518.50 0.000 0.000 0.000 519.00 0.031 0.008 0.008 520.00 0.046 0.038 0.046 521.00 0.063 0.054 0.101 522.00 0.082 0.073 0.173 523.00 0.102 0.092 0.265 524.00 0.124 0.113 0.378 525.00 0.147 0.135 0.514 526.00 0.172 0.159 0.673 527.00 0.198 0.185 0.858 528.00 0.226 0.212 1.070 529.00 0.256 0.241 1.311 530.00 0.287 0.272 1.583 Device Routing Invert Outlet Devices #1 Primary 518.50' 30.0" Round Culvert L= 102.0' RCP, groove end projecting, Ke= 0.200 Inlet / Outlet Invert= 518.50' / 515.00' S= 0.0343 '/' Cc= 0.900 n= 0.013, Flow Area= 4.91 sf #2 Device 1 518.50' 2.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Device 1 525.90' 16.0" W x 12.0" H Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #4 Device 1 526.90' 60.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=0.25 cfs @ 17.94 hrs HW=524.22' TW=504.62' (Dynamic Tailwater) t1=Culvert (Passes 0.25 cfs of 62.46 cfs potential flow) 2=Orifice/Grate (Orifice Controls 0.25 cfs @ 11.43 fps) 3=Orifice/Grate ( Controls 0.00 cfs) =Orifice/Grate ( Controls 0.00 cfs) ACSA Detention - A03 Prepared by Dewberry- Richmond Office Type // 24-hr 1 YEAR Rainfall=3.04" Printed 9/9/2022 Pond IP: SWM7 Hydrograph / I 14 '�■Pnmary 13 -i-- iiii ii -��IOIW}/1rp�V.IQaV- I I I I I I I I _ II 12, -Storage=I 0�40& a#- ,6 �' __I __l__7__r__i__�__r__ 9 -rr 7_r__rJJ --r- _ 1 1 I I I I I I I I I _1 _L _I _J _1_L _I _J _J _L _I _J _1 _L_J _J _1 _L _L_J a I I I I I I I I I I I I / I I I I I I O7-r T -I -7 -r T-1 -1 -r T-1 -T -r -I -1 -T -r -r -I _L _I__J _1 _L_ I__J _1 _L _L_J 6 I I I I I I I I I I I I I / 4 I I I I I I I I I I I I I I 3- 2- 4 5 6 7 8 9 10 11 12 13 Time (hours) ACSA Detention - A03 Prepared by Dewberrv- Richmond Office Type 11 24-hr 1 YEAR Rainfall=3.04" Summary for Pond 2P: SWM2 Printed 9/9/2022 Inflow Area = 0.330 ac, 39.39% Impervious, Inflow Depth > 1.06" for 1 YEAR event Inflow = 0.64 cfs @ 11.97 hrs, Volume= 0.029 of Outflow = 0.21 cfs @ 12.07 hrs, Volume= 0.029 af, Atten= 67%, Lag= 6.5 min Primary = 0.21 cfs @ 12.07 hrs, Volume= 0.029 of Routed to Reach 2R : A03 Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Peak Elev= 530.92' @ 12.07 hrs Surf.Area= 615 sf Storage= 284 cf Plug -Flow detention time= 8.8 min calculated for 0.029 of (100% of inflow) Center -of -Mass det. time= 8.3 min ( 858.2 - 850.0 ) Volume Invert Avail.Storage Storage Description #1 530.00' 2,392 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 530.00 0 0 0 531.00 667 334 334 532.00 1,018 843 1,176 533.00 1,414 1,216 2,392 Device Routing Invert Outlet Devices #1 Primary 530.00' 3.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #2 Primary 531.90' 20.0' long x 0.7' breadth Broad -Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 Coef. (English) 2.76 2.82 2.93 3.09 3.18 3.22 3.27 3.30 3.32 3.31 3.32 Primary OutFlow Max=0.21 cfs @ 12.07 hrs HW=530.92' TW=0.00' (Dynamic Tailwater) �1=Orifice/Grate (Orifice Controls 0.21 cfs @ 4.30 fps) 2= B road-C rested Rectangular Weir( Controls 0.00 cfs) ACSA Detention - A03 Prepared by Dewberry- Richmond Office Type // 24-hr 1 YEAR Rainfall=3.04" Printed 9/9/2022 Pond 2P: SWM2 Hydrograph ■ITIM 0.7 ' i _____i__r________i__r_ _r__r __- i i i__i__, __r __i__i__ Primary 0.6 T__ T__�_ T__T__� P k :_ eV_=_3P:8 L _L_ --r-r--r--r-r--r--r--� �_ r__ - � _ � +_1 --r- r_ p��� �(, -I --- Lt�re:F28 -d- 0.5 0.45 ,.. , LL 0.25 021 �N -J--L-_'--J--J--L----J--L----J-- 0.15 In 1 4 5 6 7 8 9 10 11 12 13 Time (hours) ACSA Detention - AO3 Prepared by Dewberrv- Richmond Office Type II 24-hr 10 YEAR Rainfall=5.56" Printed 9/9/2022 ,° Summary for Subcatchment 1S: Existing DA Runoff = 10.83 cfs @ 12.10 hrs, Volume= 0.781 af, Depth> 1.41" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type II 24-hr 10 YEAR Rainfall=5.56" Area (ac) CN Description 0.380 61 Managed Turf- B 6.030 55 Wooded - B 0.140 98 Impervious 0.110 80 Managed Turf- D 6.660 57 Weighted Average 6.520 97.90% Pervious Area 0.140 2.10% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 15.8 Direct Entry, Subcatchment 1S: Existing DA Hydrograph 12 I -__II__ �I__I________II __II __I`__ __i___I__�__�__i __I __ ■Runoff Type II 24-hr 10 10 10 YEAR Rainfall=5.56" -- Runoff Area=6.660 ac -- 8 Runoff Volume=0.781 of -- N 7 Runoff Depth>1.41' 36 Tc=15.8 min LL 5 I CN=57 4 _4 _F 3 I 2 I I I I I I I I I I 11 12 13 Time (hours) I I I I II II II II I I II I I II I I I I _L _1 I I I I I l I I I I I I I ACSA Detention - AO3 Prepared by Dewberrv- Richmond Office Type II 24-hr 10 YEAR Rainfall=5.56" Printed 9/9/2022 Summary for Subcatchment 2S: Existing Offsite AO3 Runoff = 6.67 cfs @ 11.96 hrs, Volume= 0.299 af, Depth> 2.63" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type II 24-hr 10 YEAR Rainfall=5.56" Area (ac) CN Description 0 LL 0.690 61 Managed Turf- B 0.240 55 Wooded - B 0.430 98 Impervious 1.360 72 Weighted Average 0.930 68.38% Pervious Area 0.430 31.62% Impervious Area Tc Length Slope Velocity Capacity Description 5.0 1 Direct Entry, Subcatchment 2S: Existing Offsite AO3 Hydrograph I I I I I I I I I I C I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I Type If 24-hr_ 10 YEAR RainfallT5.l56"' Runoff Area=i.366 ac RungfflllVolume=,0.299 of Runoff Depth>2.63" I I I __1--.-Tc-5.110 min I I I I I I I I I I I I I I ''///��� QN=71 I I I I I I I I I r I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I II II II i I I I I I I I I I I I I I I I I 9 1 2 3 4 5 6 7 8 9 19 11 12 13 14 15 16 17 18 19 29 21 22 23 24 Time (hours) ❑ Runoff ACSA Detention - AO3 Prepared by Dewberry- Richmond Office Type 11 24-hr 10 YEAR Rainfall=5.56" Printed 9/9/2022 Summary for Subcatchment 4S: Mite AO1 Runoff = 6.47 cfs @ 11.96 hrs, Volume= 0.290 af, Depth> 2.63" Routed to Pond 1 P : SWM1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type II 24-hr 10 YEAR Rainfall=5.56" Area (ac) CN Description " 0.650 61 Managed Turf- B " 0.240 55 Wooded - B " 0.430 98 Impervious 1.320 72 Weighted Average 0.890 67.42% Pervious Area 0.430 32.58% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Subcatchment 4S: Offsite AO1 Hydrograph 7 ■Runoff 4 3 � 2 16 *EAR RaWallT5.56" un-b Fe�= ai- ft4n_gff- V410me=%290 elf - ii--- , rF,tiU7.w1111M] CAN=72 11 12 13 Time (hours) ACSA Detention - A03 Prepared by Dewberry- Richmond Office Type 11 24-hr 10 YEAR Rainfall=5.56" Summary for Subcatchment 5S: Proposed SWM A01 Runoff = 28.98 cfs @ 11.98 hrs, Volume= 1.423 af, Depth> 3.38" Routed to Pond 1 P : SWM1 Printed 9/9/2022 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type II 24-hr 10 YEAR Rainfall=5.56" Area (acl CN Descriotion " 2.480 61 Managed Turf- Onsite " 2.570 98 Impervious - Onsite 5.050 80 Weighted Average 2.480 49.11 % Pervious Area 2.570 50.89% Impervious Area Tc Length Description 7.0 Direct Entry, Subcatchment 5S: Proposed SWM A01 Hydrograph 32 --------- -- -- -- -------------- -- -- --------- -- -- -- -- -- 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 --r--r-r--r--r--r --r --r 1 1--r--r--r--r-- 30 1 1 1 1 1 1 1 28.98 cfa 1 1 1 1 1 1 1 1 28 __ I_ 1 1 1 1 I I 1 1 1 __________________________ 1------1---1- 11---11---1� ��-- ---"-- - 26 I 1 1 1 1 I I 1 1 1 I 1 1 1 1 I I 1 1 1 1 r 1 -, -, -, -r- r r 1 1 -, -, �o- EARRatnfall;;& ' 24 , 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I I_ I_ J__1_ L_ L_ L_ I_ I_ I LRdnbfF-Aret=5.050 - 22 I I I I I I I I I I I I at: 1 I 26 ' --;--1--r--r--r--;--; --, --1, --1--;--'R4nOff�V'_I 'm�e=1.�42-a�f - ury� 18 1 1 1 1 1 1 1 --I----- -- ------ --------- -- 1 ----+-A1uno#:D0ih> �S�'-- 1 1 1 1 1 1 1 3 16 o ' I 1 1 1 1 I I 1 1 1 1 I 1 1 1 1 I tI 1 1 1 1 __r__�__r__r__'__T__r__r__r__�__� __*--T--r--r-----I- r - -0 fi�_- 1 1 1 1 1 1 1 1 1 1 1 1 T 1 1 n 14 L__1--J--,--1--1--L--L--1---1--J 12 - --1--1--L--L--1---1--J--1--1--L--L-- 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I 1 1 1 1 1 1 I 1 1 I I 10 1 1 1 1 1 1 1 1 1 1 1 1 1 1 8 ___---- _I__I__I__I__I__I___I___I___I g, I 1 1 1 1 I I 1 1 1 1 I 1 1 1 1 I I 1 1 1 1 --r-1--r--r--r--r--r--r--1r--r-�_-r-r-r-r--I--l--r--T--r--r-_ 4' 1 1 1 1 1 1 1 1 1 1 1 I 1 1 1 1 ___I__J__J__1__L__L__ 2 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 Time (hours) ■ Runoff ACSA Detention - A03 Type 11 24-hr 10 YEAR Rainfall=5.56" Prepared by Dewberry- Richmond Office Printed 9/9/2022 Summary for Subcatchment 6S: Bypass A01 Runoff = 5.01 cfs @ 11.99 hrs, Volume= 0.242 af, Depth> 2.54" Routed to Reach 1 R : AO Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type II 24-hr 10 YEAR Rainfall=5.56" Area (ac) CN Description " 0.840 61 Managed Turf- Onsite " 0.300 98 Impervious - Onsite 1.140 71 Weighted Average 0.840 73.68% Pervious Area 0.300 26.32% Impervious Area Tc Length 7.0 Description Direct Entry, Subcatchment 6S: Bypass A01 Hydrograph I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I Z I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I i I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I II II II II I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I TYpg I I I I I I I I I 10 YEAR RainfallT5.56 Runbff Areti=1.140 arc I I I I I I I I I I I R0ngff'I Vg10me='10.242 elf btunoff DepfW -54i" I I I I I I I I I I I Tc=7.0 libih " T C0IY 7K I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I - r--r --r--r I I I I I I I I 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) ■ Runoff ACSA Detention - AO3 Prepared by Dewberrv- Richmond Office Type II 24-hr 10 YEAR Rainfall=5.56" Printed 9/9/2022 Summary for Subcatchment 7S: Offsite AO3 Runoff = 0.13 cfs @ 11.97 hrs, Volume= 0.006 af, Depth> 1.71" Routed to Pond 2P : SWM2 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type II 24-hr 10 YEAR Rainfall=5.56" Area (ac) CN Description 0.040 61 Managed Turf- B 0.040 100.00% Pervious Area Tc Length 5.0 L7 0.1 0.1 0.1 0. Description Direct Entry, Subcatchment 7S: Offsite AO3 Hydrograph I I I I I I I I 7Ype-II', Z4-hr 0 YEARRainfaff#5.a6" Runbff Area=0.040 ac Runoff',Volume=0.00$ of ----Runoff Depthy4.71"- Tc=5.10 m hh- QN=61 --,--T--i- ------,--T --I - II II IIII IIIII �IIII 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) ❑ Runoff ACSA Detention - A03 Prepared by Dewberry- Richmond Office Type 11 24-hr 10 YEAR Rainfall=5.56" Summary for Subcatchment 8S: Proposed SWM A03 Runoff = 1.70 cfs @ 11.96 hrs, Volume= 0.077 af, Depth> 3.19" Routed to Pond 2P : SWM2 Printed 9/9/2022 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type II 24-hr 10 YEAR Rainfall=5.56" Area (ac) CN Description " 0.160 61 0.130 98 0.290 78 Weighted Average 0.160 55.17% Pervious Area 0.130 44.83% Impervious Area Tc Length 5.0 N 1 0 Description Direct Entry, Subcatchment 8S: Proposed SWM A03 Hydrograph Type II', 24-hr 10 YEAR RainfallT5.56 Runbff Areti=0.290 at: �tLpngff', Vpl0me=0.077 elf 1tunoff Depth>3.190 Tc�5.'0 fnib N=7 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) ■ Runoft ACSA Detention - A03 Prepared by Dewberrv- Richmond Office Type II 24-hr 10 YEAR Rainfall=5.56" Summary for Subcatchment 9S: Bypass A03 Runoff = 1.28 cfs @ 11.96 hrs, Volume= 0.060 af, Depth> 3.78" Routed to Reach 2R : A03 Printed 9/9/2022 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type II 24-hr 10 YEAR Rainfall=5.56" Area (ac) CN Description 0.040 61 Managed Turf- B 0.080 98 Impervious 0.070 80 Managed Turf- D 0.190 84 Weighted Average 0.110 57.89% Pervious Area 0.080 42.11% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Subcatchment 9S: Bypass A03 Hydrograph ❑ Runoff Type II, 24-hr 10 YEAR RainfallT5.56" u --- Rnbff Area -0.190 ac Rungff',Volume=',0.p60 of " Runoff Depth>3.78" LL Tc=5.0 min QN=84 11 12 13 14 Time (hours) ACSA Detention - A03 Prepared by Dewberry- Richmond Office Type 11 24-hr 10 YEAR Rainfall=5.56" Summary for Reach 1R: A01 Printed 9/9/2022 Inflow Area = 7.510 ac, 43.94% Impervious, Inflow Depth > 2.06" for 10 YEAR event Inflow = 5.62 cfs @ 12.24 hrs, Volume= 1.286 of Outflow = 5.61 cfs @ 12.25 hrs, Volume= 1.284 af, Atten= 0%, Lag= 1.0 min Routed to Reach 2R : A03 Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Max. Velocity= 1.06 fps, Min. Travel Time= 1.8 min Avg. Velocity = 0.54 fps, Avg. Travel Time= 3.4 min Peak Storage= 591 cf @ 12.25 hrs Average Depth at Peak Storage= 0.35' , Surface Width= 15.94' Bank -Full Depth= 10.00' Flow Area= 415.0 sf, Capacity= 2,916.59 cfs 14.00' x 10.00' deep channel, n= 0.050 Earth, long dense weeds Side Slope Z-value= 2.5 3.0 7' Top Width= 69.00' Length= 111.6' Slope= 0.0055'/' Inlet Invert= 504.58', Outlet Invert= 503.97' • • 1 Avo.:Flow De N • ,I I 1 N 1 N 1 . • . ,, 4 5 6 7 3 9 10 11 12 13 Time (hour) ■ Inflow ■ outlimll ACSA Detention - A03 Prepared by Dewberrv- Richmond Office Type II 24-hr 10 YEAR Rainfall=5.56" Printed 9/9/2022 Summary for Reach 2R: A03 Inflow Area = 8.030 ac, 43.71 % Impervious, Inflow Depth > 2.13" for 10 YEAR event Inflow = 6.57 cfs @ 12.06 hrs, Volume= 1.426 of Outflow = 6.57 cfs @ 12.06 hrs, Volume= 1.426 af, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Reach 2R: A03 Hydrograph ■ Inflow ■ Outflow Time (hours) ACSA Detention - A03 Prepared by Dewberrv- Richmond Office Type II 24-hr 10 YEAR Rainfall=5.56" Summary for Pond 1P: SWM1 Printed 9/9/2022 Inflow Area = 6.370 ac, 47.10% Impervious, Inflow Depth > 3.23" for 10 YEAR event Inflow = 35.24 cfs @ 11.98 hrs, Volume= 1.713 of Outflow = 4.86 cfs @ 12.26 hrs, Volume= 1.045 af, Atten= 86%, Lag= 16.9 min Primary = 4.86 cfs @ 12.26 hrs, Volume= 1.045 of Routed to Reach 1 R : A01 Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Peak Elev= 526.92' @ 12.26 hrs Surf.Area= 0.196 ac Storage= 0.844 of Plug -Flow detention time= 209.2 min calculated for 1.045 of (61% of inflow) Center -of -Mass det. time= 99.5 min ( 916.6 - 817.2 ) Volume Invert Avail.Storage Storage Description #1 518.50' 1.583 of Custom Stage Data (Prismatic)Listed below Elevation Surf.Area Inc.Store Cum.Store (feet) (acres) (acre-feet) (acre-feet) 518.50 0.000 0.000 0.000 519.00 0.031 0.008 0.008 520.00 0.046 0.038 0.046 521.00 0.063 0.054 0.101 522.00 0.082 0.073 0.173 523.00 0.102 0.092 0.265 524.00 0.124 0.113 0.378 525.00 0.147 0.135 0.514 526.00 0.172 0.159 0.673 527.00 0.198 0.185 0.858 528.00 0.226 0.212 1.070 529.00 0.256 0.241 1.311 530.00 0.287 0.272 1.583 Device Routing Invert Outlet Devices #1 Primary 518.50' 30.0" Round Culvert L= 102.0' RCP, groove end projecting, Ke= 0.200 Inlet / Outlet Invert= 518.50' / 515.00' S= 0.0343 '/' Cc= 0.900 n= 0.013, Flow Area= 4.91 sf #2 Device 1 518.50' 2.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Device 1 525.90' 16.0" W x 12.0" H Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #4 Device 1 526.90' 60.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=4.86 cfs @ 12.26 hrs HW=526.92' TW=504.93' (Dynamic Tailwater) t1=Culvert (Passes 4.86 cfs of 79.11 cfs potential flow) 2=Orifice/Grate (Orifice Controls 0.30 cfs @ 13.90 fps) 3=Orifice/Grate (Orifice Controls 4.40 cfs @ 3.30 fps) =Orifice/Grate (Weir Controls 0.15 cfs @ 0.47 fps) ACSA Detention - A03 Prepared by Dewberry- Richmond Office Type ll 24-hr 10 YEAR Rainfall=5.56" Printed 9/9/2022 Pond IP: SWM7 Hydrograph _ _J -1 _-1 -F -F_ ■Inflow __ __�__,_ '--�--'--"__---'------"--i------'-- ■Prima ry 38 I 35.za GB I I I I -r 36 ,' I - n lt�vvWe �6;3701a�- 34 I I I --I--�--r--r--r--r-,--r--r-�--� --r - - I r r r- 32 30 r 1 1 1 1 1 1 1 1 1 1 1 Iy� Ih IIQj 28 \Id�a\}jr ` A�$j{I �i�IIiLII� L__I__SbDrA"T�Y'S4taf- 26 24 •' _{ _F_J .@ 22 _I -4 -F _I _I _4 -1 _I _� _I 26 3 , - -7 -Y -Y -I -I -Y -Y -I --I -y -r -I -7 -T -Y -I -� 0 18 __-__r__r__r__I__ 16 14 12 ___________________----- ___ __________________________ 10 6 4.W�y 4 5 6 7 8 9 10 11 12 13 Time (hours) ACSA Detention - A03 Prepared by Dewberrv- Richmond Office Type II 24-hr 10 YEAR Rainfall=5.56" Summary for Pond 2P: SWM2 Printed 9/9/2022 Inflow Area = 0.330 ac, 39.39% Impervious, Inflow Depth > 3.01" for 10 YEAR event Inflow = 1.82 cfs @ 11.96 hrs, Volume= 0.083 of Outflow = 0.71 cfs @ 12.06 hrs, Volume= 0.083 af, Atten= 61 %, Lag= 5.9 min Primary = 0.71 cfs @ 12.06 hrs, Volume= 0.083 of Routed to Reach 2R : A03 Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Peak Elev= 531.94' @ 12.06 hrs Surf.Area= 996 sf Storage= 1,113 cf Plug -Flow detention time= 24.5 min calculated for 0.083 of (100% of inflow) Center -of -Mass det. time= 24.0 min ( 844.5 - 820.6 ) Volume Invert Avail.Storage Storage Description #1 530.00' 2,392 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 530.00 0 0 0 531.00 667 334 334 532.00 1,018 843 1,176 533.00 1,414 1,216 2,392 Device Routing Invert Outlet Devices #1 Primary 530.00' 3.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #2 Primary 531.90' 20.0' long x 0.7' breadth Broad -Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 Coef. (English) 2.76 2.82 2.93 3.09 3.18 3.22 3.27 3.30 3.32 3.31 3.32 Primary OutFlow Max=0.71 cfs @ 12.06 hrs HW=531.94' TW=0.00' (Dynamic Tailwater) �1=Orifice/Grate (Orifice Controls 0.32 cfs @ 6.48 fps) 2= B road-C rested Rectangular Weir(Weir Controls 0.39 cfs @ 0.53 fps) ACSA Detention - A03 Prepared by Dewberry- Richmond Office Pond 2P: SWM2 Hydrograph Type ll 24-hr 10 YEAR Rainfall=5.56" Printed 9/9/2022 ■ Inflow ■ Primary Inflow ,Are00:,330 ',ac PoAk F-10=¢3,1.941 Storage=1,1 �'13, cf a 71 ch 1 2 3 4 5 6 7 8 9 10 11 12 13 Time (houm) APPENDIX D: Sediment Basin 4S Offsite A( Subcat Reach Aon Llnk 5S po ed SWM A01 ACSA Detention - AO1 Prepared by Dewberrv- Richmond Office Rainfall Events Listing (selected events) Event# Event Storm Type Curve Mode Duration B/B Depth AMC Name (hours) (inches) 1 25 YEAR Type II 24-hr Default 24.00 1 6.83 2 Printed 9/9/2022 ACSA Detention - AO1 Prepared by Dewberrv- Richmond Office Type II 24-hr 25 YEAR Rainfall=6.83" Printed 9/9/2022 Summary for Subcatchment 4S: Offsite AO1 Runoff = 8.97 cfs @ 11.96 hrs, Volume= 0.405 af, Depth> 3.68" Routed to Pond 1P : SWM1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type II 24-hr 25 YEAR Rainfall=6.83" Area (ac) CN Description 0.650 61 Managed Turf- B 0.240 55 Wooded - B 0.430 98 Impervious 1.320 72 Weighted Average 0.890 67.42% Pervious Area 0.430 32.58% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Subcatchment 4S: Offsite AO1 Hydrograph 1 I I I 1 1 I I I I 1 I 1 1 1 r__r__r__r__r__I___1_.� I I 1 1 I I 1 I I 1 1 I I 1 I 1 I I I 1 1 I I I I 1 I I I 1 1 I I I I 1 1 I I 1 1 I I I I 1 I I I 1 1 I I I I 1 I I I 1 1 I I I I 1 I I 1 1 1 __1__L__I___I__J_. I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I 1 1 1 1 1 1 I I 1 1 1 1 I I 1 1 I I 1 1 1 1 I I 1 1 I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I 1 1 I I I I 1 1 I I I I 11 12 13 Time (hours) ■ RunoH I I I 1 1 I I I I 1 1 Runoff Depth>3.68P'-- Tc=5.0 f,n4t- CN=72 - I I I I I I I I I I ACSA Detention - A01 Prepared by Dewberry- Richmond Office Type 1124-hr 25 YEAR Rainfa&6.83" Summary for Subcatchment 5S: Proposed SWM A01 Runoff = 38.32 cfs @ 11.98 hrs, Volume= 1.907 af, Depth> 4.53" Routed to Pond 1 P : SWM1 Printed 9/9/2022 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type II 24-hr 25 YEAR Rainfall=6.83" Area (ac) CN Descriotion " 2.480 61 Managed Turf- Onsite " 2.570 98 Impervious - Onsite 5.050 80 Weighted Average 2.480 49.11 % Pervious Area 2.570 50.89% Impervious Area Tc Length Description 7.0 Direct Entry, Subcatchment 5S: Proposed SWM A01 Hydrograph q2 � ------------------------------ __I___I__J__J__L__L__L__I___I__L__ I 4038 , 36 --r-I--r--r--r-r--r--r--I---I--r ' --I_ I --r --I--7--7--r--r--r --r --I--I 32 30 ------L--L--L--L--L--L-----'--� 28 " _I 22 _ _ I_ ---------------------------- I I I I I I I I I I I o 20 LL 18 i 16 _ I -I -I -y -y -4 12 I--r--I--�__�--r--r--r--r--r-. , 6 q - r--I---I--r-r-r--r--r-- --------7-----I-------------------- I1__L__L__I__J__J__J__1__L__L__ I }-1--1--L--L--L-J--J- - pe1--1--L--L-- --T--r--r--r--r-_I__l__T__T__r__r__ 26 YEAR RWrifallT6.83 - -; - - �Runbff_Aker-"50 at, I I I I I I I I I I I --rtpffrY_plili►ne=f:$II��= 11 --r- kunoffbDI -/�pih>453�F TI I I I IY�7.ejnjjy N 8 I --I_ I I I I I I I I I I I I I I I I I I I I I I I I I I I I 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 Time (hours) ■ Runoff ACSA Detention - A01 Prepared by Dewberrv- Richmond Office Type II 24-hr 25 YEAR Rainfall=6.83" Summary for Pond 1P: SWM1 Printed 9/9/2022 Inflow Area = 6.370 ac, 47.10% Impervious, Inflow Depth > 4.35" for 25 YEAR event Inflow = 47.00 cfs @ 11.98 hrs, Volume= 2.311 of Outflow = 28.66 cfs @ 12.06 hrs, Volume= 1.635 af, Atten= 39%, Lag= 4.7 min Primary = 28.66 cfs @ 12.06 hrs, Volume= 1.635 of Routed to Reach 1 R : A01 Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Peak Elev= 527.46' @ 12.06 hrs Surf.Area= 0.211 ac Storage= 0.957 of Plug -Flow detention time=166.7 min calculated for 1.634 of (71% of inflow) Center -of -Mass det. time= 69.2 min ( 878.0 - 808.8 ) Volume Invert Avail.Storage Storage Description #1 518.50' 1.583 of Custom Stage Data (Prismatic)Listed below Elevation Surf.Area Inc.Store Cum.Store (feet) (acres) (acre-feet) (acre-feet) 518.50 0.000 0.000 0.000 519.00 0.031 0.008 0.008 520.00 0.046 0.038 0.046 521.00 0.063 0.054 0.101 522.00 0.082 0.073 0.173 523.00 0.102 0.092 0.265 524.00 0.124 0.113 0.378 525.00 0.147 0.135 0.514 526.00 0.172 0.159 0.673 527.00 0.198 0.185 0.858 528.00 0.226 0.212 1.070 529.00 0.256 0.241 1.311 530.00 0.287 0.272 1.583 Device Routing Invert Outlet Devices #1 Primary 518.50' 30.0" Round Culvert L= 102.0' RCP, groove end projecting, Ke= 0.200 Inlet / Outlet Invert= 518.50' / 515.00' S= 0.0343 '/' Cc= 0.900 n= 0.013, Flow Area= 4.91 sf #2 Device 1 518.50' 2.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Device 1 525.90' 16.0" W x 12.0" H Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #4 Device 1 526.90' 60.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=28.57 cfs @ 12.06 hrs HW=527.46' TW=505.57' (Dynamic Tailwater) t1=Culvert (Passes 28.57 cfs of 82.05 cfs potential flow) 2=Orifice/Grate (Orifice Controls 0.31 cfs @ 14.35 fps) 3=Orifice/Grate (Orifice Controls 6.56 cfs @ 4.92 fps) =Orifice/Grate (Weir Controls 21.70 cfs @ 2.45 fps) ACSA Detention - A01 Prepared by Dewberry- Richmond Office Type H 24-hr 25 YEAR Rainfa&6.83" Printed 9/9/2022 Pond IP: SWM7 Hydrograph �I__11__'i __1__ 1__11__'i __�__ �__ �I_____li __�__JI__11 __li _ �__ 1__11__l7__li _ I__ Inflow i I i I n.ao as Pnma 50 _'__4--4-_`__'___'__'__`__'__�__' - nfil w Are'67611 611a �__� �_c_'__ ry as � � I I I I I I I I 1 - eV= _ Stbrage=0'I; 95TII of 35 __,__-__r__r__r__,__ I l i i i I I I I I I I l 30---L--L--L------L--L--`--za ss ors--L----L--L--L- �__--L--L--L- i I I I i i I I i i I i I I I i i I I I i c 2,9 _ _,__y__i__r__,___,__Y__r__,__y__ LL 26 -------L--L--I-- -__ �__L--L--I-- -__ i I I I i i I I i i I i I I I i i I I I i 10 1 i_ ____i Iii___________i__ 4 5 6 7 8 9 10 11 12 13 Time (houB)