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WPO202000017 Stormwater Management Maintenance Agree. 2021-03-30
SHIMP ENGINEERING, P.C. Design Focused Engineering Stormwater Management Plan Calculation Packet Proffit Road Townhomes South Prepared by: Shimp Engineering WPO-2020-00017 October 19, 2020 9121E. Hriglh St. tr i ff fesAg, 67/f�.t`i4 M � 454.2,27..3140 fl r7i9tre,'e, ,�.mar5n, SHIMP ENGINEERING, P.C. Design Focused Engineering October 19, 2020 County of Albemarle Department of Community Development 401 McIntire Road Charlottesville, VA 22902 Regarding: Proffit Road Townhomes South Stormwater Management Plan Dear David, The purpose of this project is to build 40 single family attached units on the southern side of Proffit Road. The total area of disturbance is 3.34 acres. Water Quantity: Runoff from the site in the predevelopment condition is analyzed at one point labeled POA. The post - development condition runoff is collected and piped to an underground detention system comprised of StormTech MC4500 chambers and an isolation row, which outlets to POA. The proposed storm sewer will outlet into an existing channel further downstream. Runoff from the site will be released at rates that comply with the energy balance equation set forth in 9VAC25-870-66-B(3). The calculations are summarized in the table below. Please note that a small portion of the drainage area to POA is from offsite. The flow from offsite was included in the energy balance equation, but no improvement factor was applied to offsite areas. PROFFIT ROAD TOWNHOMES SOUTH I 24 Hr 1 year Storm: I �� a Qz W a(Qra. KVr WdYKVv uu = 0.12 MaxQa.H 0.41 cts = 0.413 Qa,« = Q38 as PreDevelopmol Post Development 10 r 1 7.6111 7.53 Water Quality According to the VRRM spreadsheet included in this packet, the target phosphorus load reduction is 3.14 lb/yr. The StormTech chambers with the isolator row are rated for 40% phosphorous removal, resulting in 1.77 Ib/yr phosphorous removal. The remaining phosphorous load 1.37 Ib/yr will be effectively reduced by the purchase of nutrient credits. SHIMP ENGINEERING, P.C. Design Focused Engineering Contents: Water Quantity Calculations: Pre -Development Drainage Area Map Pre -Development Hydro CAD Report Post -Development Drainage Area Maps Post -Development Inlets Drainage Area Maps Temp. SCC Drainage Area Map Post -Development HydroCAD Report Energy Balance Equations TOC Calculations Nomographs VDOT LD-204 VDOT LD-209 VDOT LD-347 VDOT LD-268 Water Quality Calculations: Pre -Development VRRM Landuse Map Post -Development VRRM Landuse Map VRRM Redevelopment Spreadsheets Independent Reports: Excerpt from NRCS Soils Report NOAA Precipitation Report SHIMP ENGINEERING, P.C. Design Focused Engineering Water Quantity Calculations: Pre -Development Drainage Area Map Pre -Development Hydro CAD Report Post -Development Drainage Area Maps Post -Development Inlets Drainage Area Maps Temp. SCC Drainage Area Map Post -Development HydroCAD Report Energy Balance Equations TOC Calculations Nomographs VDOT LD-204 VDOT LD-209 VDOT LD-347 VDOT LD-268 LEGEND ON -SITE IMPERVIOUS ON -SITE MANAGED TURF ® ON -SITE WOODS ® OFF -SITE IMPERVIOUS OFF -SITE MANAGED TURF ® OFF -SITE WOODS PRE DEV ONSHE CN 96 61 55 Cover Area (SF) Area (me) % Pavement 13,615 0.31 11.2% Impervious 13,615 0.31 11.2% Managed Turf 107,675 2.48 88.8% Woods 15,686 026 12.9% Tosal 1212,100.m WRCHTM CN 65 PRE DEV OFFSTTE Cover I Area (SF) Area (ao) I % Pavement 770 0.02 3.3% Impervious 770 0.02 3.3% CN Iaaaged surf 17,210 0.40 Woods 12 R797%%We(HTE 23139 , 0.53 Cioml SIIIMPENGINEERING, P.C. PNGR'FF,RING-IAM)PlANNRI'G-PR0"TMAN96F.1j0T `---- ----------- LJ i w \ -`OFFSITE WOODS �\ OFFSITE IMP. `\ _ A=0.1;AC A=0.02AC `\TOTAL Pam- -V / �I- E --k- ��y y�y'�"y �y, mass-lr�'✓�,SAy�^yv�y�' \ — _ Ns DA=3.68AC �^ `I `k E N` e �\ 0000 OFFSITE TURF , W. �� �� Ifik}1`Ifi" �k 4 k k E k k r \ ov RL n1 _ A=0.40AC k `� k 1— k k E\ k k k / \ FL W y,fk am k k k� k E k k k k k E k nE/ N /k E -��k. k E �T.fk —_`k k k\`\ E k k\ k k E\ k E k EE / E k k f\ A\ E k�f \`k f f E f E Y E f f f f E \\ E f I\ \�- 1\ i �� \ �5E rh. 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E `rN E\ f E S--f� f iP E f f E� E E\ f E \ �\ �yl / \ N \ \ \ E \E E E \ E `� E E ��f E fv E`—F� f E f E.Q f\� E E \E E f\ \ E E E E E \ E E E E\\ E E E E ��--�-- E E f E E E E E F� E E E E iP� E 1 1 E E E E E E E \�\E 4F E E E E E E\\ E FA \\E I 11 f f f E f f E f\ f E f A\ f f \�f�� f E f E f E E f E E f E f\ E E f E E 44 E E Nf '� E jp E E E E\'sf��f E E E E E E f EiP E E E E W0E E E\ E\ I\ f'p E TOOT'pE•,I ONNCITEE E E E'er E// E E NEE \`E E E �E""�Enc�{---E______ . E E E E N�0 E �E E E\ E E f f bTdc_% MIkNUTE k f f E f Pam\ f f Irylc- �P E \ E E E E f E E E E f — E f E E f E f/�_4� f E E ell fON EN�Rg1101`If \ f E f f E f E f Y" f E i/ E E —�-- F--E E {\/ E E E E E E (� 1NEUTESs ),./�� 51�-�y f\ E E E E E \1E E E E E E E E E E es c\18•Q E E �' V`�y-5 E E E E E E E/ E E 0 1 E f f f f N E f E Es f f f E tlf E f f E, } E \P\ E f f E/ f E E `f NW E E E E Fs� E E E "s�E E E E E f E E E E r''� E E U, E E / f E E E\ E E E / �F— E---E__ E E E E E E W E E E E E j E E E E E c/y'yj1'�( E\ E ENa+ E 4/ E E E f E E \ f f f l---f—_ f f E E E f £--{�� f f f E E jj''��S']Y' f s� f f f� f f �' f f f E,—�—_ E /f EU` E f E f f f Y' E E/ f E f/ E E E `oaf E\�--'— / , E E N� E E\\_�F E E E E C E E E N E E E E E /E E E / E E E E E E E w TOT%.Q�L OFFSIT� / / 1 J +P, E--E E E E E E 5g3EC E E E Es E E E t�E E E/ E E /E E N E E/ E E E E I 1 -T&-A MINUTES f f E f E f f .0 f f I E f E1 f f '.o f f _1E f E f II _4 —_E — E E E E E E f \\E E E 1, E 0 E E E E 1 -' ` ONSITE TURF ', E E `'rnE E �E E E E E E �i tTW 11 -48AC —�F —„ -� F w F F F E E E 'E E F—Fes•--T—F—Ir_Z,-- _ O�JSJTEII�IM F F F F F �U` Sly O F F F F •F F F I \\ , PROFFIT ROAD TOWNHOMES SOUTH PRE-DEVELOPEMENT DRAINAGE AREA MAP REVISION DATE: 10/19/2020 ,tale: "=5C 50 1S 2S Pre-Dev Onsite Pre-Dev Offsite 3L POA1 Subcat Reach On Link Drainage Diagram for Pre Development Prepared by SHIMP ENGINEERING, Printed 10/19/2020 HydroCAD® 9.10 s/n 07054 0 2011 HydroCAD Software Solutions LLC Pre Development Pre Development Type 1124-hr 1 yr, 24 hr Rainfall=2.97 Prepared by SHIMP ENGINEERING Printed 10/19/2020 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Paae 2 Time span=0.00-36.00 hrs, dt=0.05 hrs, 721 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: Pre-Dev Onsite Runoff Area=3.150 ac 9.84% Impervious Runoff Depth=0.46" Tc=18.0 min CN=64 Runoff=1.20 cfs 0.120 of Subcatchment 2S: Pre-Dev Off site Runoff Area=0.540 ac 3.70% Impervious Runoff Depth=0.35' Tc=18.0 min CN=61 Runoff=0.13 cfs 0.016 of Link 3L: POA1 Inflow=1.34 cfs 0.136 of Primary=1.34 cfs 0.136 of Total Runoff Area = 3.690 ac Runoff Volume = 0.136 of Average Runoff Depth = 0.44" 91.06% Pervious = 3.360 ac 8.94% Impervious = 0.330 ac Pre Development Type 1124-hr 1 yr, Prepared by SHIMP ENGINEERING HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Pre-Dev Onsite Runoff = 1.20 cfs @ 12.15 hrs, Volume= 0.120 af, Depth= 0.46" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-36.00 hrs, dt= 0.05 hrs Type II 24-hr 1 yr, 24 hr Rainfall=2.97" Area (ac) CN Description Pre Development 24 hr Rainfall=2.97' Printed 10/19/2020 0.360 55 Woods, Good, HSG B 2.480 61 >75% Grass cover, Good, HSG B 0.310 98 Paved parking, HSG B 3.150 64 Weighted Average 2.840 90.16% Pervious Area 0.310 9.84% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 18.0 Direct Entry, Pre Development Type 1124-hr 1 yr, Prepared by SHIMP ENGINEERING HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: Pre-Dev Offsite Runoff = 0.13 cfs @ 12.16 hrs, Volume= 0.016 af, Depth= 0.35" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-36.00 hrs, dt= 0.05 hrs Type II 24-hr 1 yr, 24 hr Rainfall=2.97" Area (ac) CN Description 0.400 61 >75% Grass cover, Good, HSG B 0.020 98 Paved parking, HSG B 0.540 61 Weighted Average 0.520 96.30% Pervious Area 0.020 3.70% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 18.0 Direct Entry, Pre Development 24 hr Rainfall=2.97' Printed 10/19/2020 Pre Development Pre Development Type 1124-hr 1 yr, 24 hr Rainfall=2.97" Prepared by SHIMP ENGINEERING Printed 10/19/2020 Summary for Link 3L: POM Inflow Area = 3.690 ac, 8.94% Impervious, Inflow Depth = 0.44" for 1 yr, 24 hr event Inflow = 1.34 cfs @ 12.15 hrs, Volume= 0.136 of Primary = 1.34 cfs @ 12.15 hrs, Volume= 0.136 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-36.00 hrs, dt= 0.05 hrs Pre Development Pre Development Type 1124-hr 10 yr, 24 hr Rainfall=5.43" Prepared by SHIMP ENGINEERING Printed 10/19/2020 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Paae 6 Time span=0.00-36.00 hrs, dt=0.05 hrs, 721 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: Pre-Dev Onsite Runoff Area=3.150 ac 9.84% Impervious Runoff Depth=1.87" Tc=18.0 min CN=64 Runoff=6.64 cfs 0.490 of Subcatchment 2S: Pre-Dev Off site Runoff Area=0.540 ac 3.70% Impervious Runoff Depth=1.63" Tc=18.0 min CN=61 Runoff=0.97 cfs 0.074 of Link 3L: POA1 Inflow=7.61 cfs 0.563 of Primary=7.61 cfs 0.563 of Total Runoff Area = 3.690 ac Runoff Volume = 0.563 of Average Runoff Depth = 1.83" 91.06% Pervious = 3.360 ac 8.94% Impervious = 0.330 ac Pre Development Type 1124-hr 10 yr, Prepared by SHIMP ENGINEERING HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Pre-Dev Onsite Runoff = 6.64 cfs @ 12.12 hrs, Volume= 0.490 af, Depth= 1.87" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-36.00 hrs, dt= 0.05 hrs Type II 24-hr 10 yr, 24 hr Rainfall=5.43" Area (ac) CN Description Pre Development 24 hr Rainfall=5.43" Printed 10/19/2020 0.360 55 Woods, Good, HSG B 2.480 61 >75% Grass cover, Good, HSG B 0.310 98 Paved parking, HSG B 3.150 64 Weighted Average 2.840 90.16% Pervious Area 0.310 9.84% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 18.0 Direct Entry, Pre Development Type 1124-hr 10 yr, Prepared by SHIMP ENGINEERING HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: Pre-Dev Offsite Runoff = 0.97 cfs @ 12.12 hrs, Volume= 0.074 af, Depth= 1.63" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-36.00 hrs, dt= 0.05 hrs Type II 24-hr 10 yr, 24 hr Rainfall=5.43" Area (ac) CN Description 0.400 61 >75% Grass cover, Good, HSG B 0.020 98 Paved parking, HSG B 0.540 61 Weighted Average 0.520 96.30% Pervious Area 0.020 3.70% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 18.0 Direct Entry, Pre Development 24 hr Rainfall=5.43" Printed 10/19/2020 Pre Development Pre Development Type 1124-hr 10 yr, 24 hr Rainfall=5.43" Prepared by SHIMP ENGINEERING Printed 10/19/2020 Summary for Link 3L: POM Inflow Area = 3.690 ac, 8.94% Impervious, Inflow Depth = 1.83" for 10 yr, 24 hr event Inflow = 7.61 cfs @ 12.12 hrs, Volume= 0.563 of Primary = 7.61 cfs @ 12.12 hrs, Volume= 0.563 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-36.00 hrs, dt= 0.05 hrs LEGEND ON -SITE IMPERVIOUS TREATED ON -SITE MANAGED TURF TREATED III OFF -SITE IMPERVIOUS TREATED OFF -SITE MANAGED TURF TREATED ® OFF -SITE WOODS TREATED ON -SITE IMPERVIOUS UNTREATED ON -SITE MANAGED TURF UNTREATED OFF -SITE MANAGED TURF UNTREATED POST DEV ONSITE TREATED Cover Area (SF) Area (ac) % BmklW and 95,000 1.95 68.70/o Pavement AND Impervious 95,000 1.95 68.79/o CN Managed Tort 38,810 0.89 31.3% 96 61 Total 1 123,810 2.84 100A% ,, 86 POST DEV OFFSITE TREATED Cover Area (SF) Area (ac) % Bolding & 770 0.02 5.5% pavement CN Impervious 770 0.02 5.5% Managed Turf 8,165 0.19 58.2% 96 b1 55 I WEG1=CN b1 moods 5,089 0.12 36.3% Total 14,024 032 100.0% POST DEV ONSITE UNTREATED Cover SIDEWALK N Fmperrvvus Area (SF) I Area (ac) I % 151 0.00 1 0.1% 151 0.003 0.1% ` N 3401 031 1 10.8% 9 D 491 1 nit 1 10 9% POST DEV OFFSITY UNTREATED Cover Area (SF) Area (ac) % ManagedTurf 9,115 021 7.4% Total 9,115 021 7.4% SINNPENGINEERM,, P.C. FeY(AiST-ERLYG-JANDPL411MW -PROJECT MANA6BEV c434> 227-5140 CN WMCff RCN b1 `------ \ - -TREATED A=0.32AC- TOTAL \QNSITE TGC=-a MINUTES TREATED A=2.84AG_ (ASSMEB-). TOC=5 MINUTES (ASSUMED) .' 0 \r . �POA� 1= • .• • • • •: a -F-- I I \ -- I ONSII TREATED 2s TOTAL SITE L1OFF%TE TREATED A=0.19AC i i\\ OFFSITE TREATED --__ _WOODS A=0.12AC �• :� i ✓' v \\ OFFSITE TREATED '� \\ IMP. A=0.02AC f CY m \ 6 IO"fAL DRAINAGE AREA=3.68AC OFFSITE UNTREATED ••• ' •�4 TURF A=0.21AC •ONSITE UNTREAT D TOTAL ��S��ISE IMP. A=0.003AC UNTREATED A=0.21 C r TOC=18 MINUTES (CALCULATED) PROFFIT ROAD TOWNHOMES SOUTH POST-DEVELOPEMENT DRAINAGE AREA MAP REVISION DATE: 10/19/2020 TURF A= 50 scale: 5C V'\ 27 \ I ! I I \ I I \ � T , 1 1 1 \ 1 I , I 1 t Z 0 50 100 15C LEGEND IMPERVIOUS PERVIOUS t FLOW LINE .II. INLET DA DIVIDE ROOFDRAIN DA DIVIDE C 1iDr disnabed Sod during E 0.6 & S assi d I®erviom C 10.9 All 1 20,463 1 5,788 1 14,675 1 0.47 0.47 AS 1 25,289 1 21,737 1 3,551 1 0.82 1 0.58 A9C 14,275 9,539 4,736 0.70 0.33 A4H 110 110 0 0.90 0.003 A4G 114 114 0 0.90 0.003 110 110 1 0 0.90 0.003 110 110 0 0." 0.003 114 114 0 0.90 0.003 NOTE: THE SCC DA MAP IS SHOWN SEPARATELY SIMPENGINEERIM,, P.C. LN0FffHING-L4NOPL4MWG-PRaECT MANAGEMENT FLOW LINE y..dA ANISTI ` - STR. A4\��� �- n �-- TOC=5 MINUTES �r� .�. .�• . . . ��.• `` ••••'• .•,•. . . ..�, -� (ASSUMED •�- �� • �r` i .ice . STR. A4D A 0. 03AC - �� -� \ ` `� i •�• TO = MIN is �I z `� ` �,��I kkkk ASSU D I \ IS • • 3 TR. A4 bA 0.003A TOC=5 OTE ( S MED- 4B DANO 00 AC r I C= 5 NU zs e" � s" r \\ — E - s s' r TR. A F = .0 3 C - -1- _ - fOC=5 IN T S � - L _ _ i ---�---- ---- , N ,L 1 w S R. 4 - - A= .0 A —I TOC 5� IN E fA S E --- r -- S R. N '----- - --- - - I i' (ASS M D Zs y ' I _ _________________ PAP - III DAB--- �__---- --'e--©---p— I I I TAOC-5 MINUTES ■ PROFFIT ROAD TOWNHOMES SOUTH INLETS DRAINAGE AREA MAP REVISION DATE: 10/19/2020 50 m" Scale: 1 "=50' -Ag — — 0.5ERC STR. A11 �A-L`05AC TOC=5 MNUTQS (ASSUMED i I I � I \ i I i i 1 I Z 0 50 100 150 rush) \ -- / _ - I.rr joiar Par Parr a r 1€\ ~--� _ I PED .�V POLE ,ONd / --_-- -_ \ Dense Trees IRON 58 / \ FOUND ? \ \ i \ \\ \\ / / I �R OPN OSE R]5K 'DE'-Y.IDT1 \I - /J LOT 31 o - •\\� � / %'. \ I \ • 1 I FROM ROAD SL — - - - - � �/�'�,( FFE 52].5 �'� \ \ I 1 /I /�' p SAN r 0 --34 FFE \ \\ \ \LOT 32 LOT 33 LOT 34 LT 35 LOT 3fi LOT 3 FFE\31. FFE 531. FE 533. F FFE 534. FFE 535. LOT 3 LT 3 LOT 4 - FFE 534. FF 534. FFE 533. -_-- \ 2 F t ___ � �� o __ � m u � 29 \\ \III • \534. 32 � \ \�\ / I -_-_ I p siE � I �� LOT FFE 52J.0 � .•, I �� \ \ \ / � 2m- I \ 30 \ \ y LOT 28 FFE 527.0 \ / I ■■ •■ \ LOT 27 FFE 527.0 I� ■• an, on w—• i��-rW—i��w—flew —w.\ w•-w—w ■ ■•+• ■!■•A�■■ O 8' DI s ' a SAN - RIVATE READ A •I Arc v Jay LIMITS OF DISTURBANCE I� �' A �\ w i 'A'• I l AREA = 3.34 1 nw \ LOT 16 \ '. +� A FFE 5315 IA I '. �" • 1\ I 1 \ l AC \—•J ••TWW 80'#2■' O FFE 528.0 \ xi �� \ i� ® 1 I tT dn •■ I\ \ \` LOT 3 0 •.. 8 ' to . 1 ) ■ 1 o J v _ _ A"N scc 17532.0 / FFE 528.0 MAiTNC v �, �\\ �fp9■IM N✓0� _ 10 L01LOT `\ I I F • V A v \I I • \ q !!ti, gI I \ \ I ` FL0535b FE / 1 .'�o A J / FFGE 9 980 A FFE'0 nanax LOT 19 / 1�0ET5325 \\ Im, •.�'.. \\ I 'ir I 5}50\ • 1 --_-- 1 / I FFE \ _ OT - 2. s2e4 FFE 5 8 0ll TEMPORARY FL0536 FLOW LINE ' SCC DA=1.29AC LDT 1nD s 1 TYP. Dense- `2s a L----EF0 �5 C VALUE =0.6 F� I _ a.o5; .5 ' :'. 1 lk Po I / FOUND _`_---- _ —_ / i Via C3— ! \ • a • � Z1 Dense Trees — —Zi IRO FOUND i' _—_______—_O\ J ----- _ PROPERTY LINE \ NOTE: FLOW LINES ARE SHOWING THE WATER FLOW THROUGH THE PIPES. THEY ARE DRAWN OFF FROM THE _ 0> ■■ BE as •■ PIPES TO ENSURE PIPES VISIBILITY ON l\ J o p ■?�'■_■.�•■�■��•. Nam, THE MAP ♦♦��I � 0 I •. �"�'��` — 50 0 50 100 150 �\ �� I I ♦J � 1 / ` \ly♦♦/I I r 11-� L IrM' II \I 1 32-29D LIMITS OF MAPLE GROVE DISTURBANCE �•�•� �� Scale: 1"=50' SHIMPENGINEERINGP.C. / ♦' 1 I / I /-� / ♦ 7 '/ /�4 .• � /CHRISTIAN AREA = 3.34 /\ ! CHURCH AC \ - �.J ♦�/\I II `°;^� PROFFIT ROAD TOWNHOMES SOUTH Evcwewc-camrra/urowc.aeo�cryn>Ac I 1 s - '1 SCC DA MAP ENaNE°° °^`w" E. °^ °'°°' '""'°"'"`_ EwP"°.`° -'^ I I I / �� ♦♦ 1 f �l I REVISION DATE: 010/19/2020 / I rM Onsite Trea 1S Onsite Treated Onsittn[reated 5P StormTech\ POA Subcat Reach Aon Link 4S ite Untreated Post Development Post Development Type 11 24-hr 1 yr, 24 hr Rainfall=2.97" Prepared by SHIMP ENGINEERING Printed 10/19/2020 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Paae 2 Time span=0.00-48.00 hrs, dt=0.05 hrs, 961 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: Offshe Treated Runoff Area=0.330 ac 6.06% Impervious Runoff Depth=0.35" Tc=5.0 min CN=61 Runoff=0.15 cfs 0.010 of Subcatchment 2S: Onsite Treated Runoff Area=2.840 ac 68.66% Impervious Runoff Depth=1.64" Tc=5.0 min CN=86 Runoff=8.31 cfs 0.387 of Subcatchment 3S: Onsite Untreated Runoff Area=0.313 ac 0.96% Impervious Runoff Depth=0.35" Tc=5.0 min CN=61 Runoff=0.15 cfs 0.009 of Subcatchment 4S: Offshe Untreated Runoff Area=0.210 ac 0.00% Impervious Runoff Depth=0.35" Tc=18.0 min CN=61 Runoff=0.05 cfs 0.006 of Pond 5P: StormTech Peak Elev=520.90' Storage=9,583 cf Inflow=8.44 cfs 0.397 of Outflow=0.26 cfs 0.397 of Link 6L: POA Inflow=0.38 cfs 0.413 of Primary=0.38 cfs 0.413 of Total Runoff Area = 3.693 ac Runoff Volume = 0.413 of Average Runoff Depth = 1.34" 46.57% Pervious = 1.720 ac 53.43% Impervious = 1.973 ac Post Development Type 1124-hr 1 yr, Prepared by SHIMP ENGINEERING HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Subcatchment 1 S: Offsite Treated Runoff = 0.15 cfs @ 11.99 hrs, Volume= 0.010 af, Depth= 0.35" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 1 yr, 24 hr Rainfall=2.97" Area (ac) CN Description 0.190 61 >75% Grass cover, Good, HSG B 0.020 98 Paved parking, HSG B 0.330 61 Weighted Average 0.310 93.94% Pervious Area 0.020 6.06% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Post Development 24 hr Rainfall=2.97' Printed 10/19/2020 Post Development Type 1124-hr 1 yr, Prepared by SHIMP ENGINEERING HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: Onsite Treated Runoff = 8.31 cfs @ 11.96 hrs, Volume= 0.387 af, Depth= 1.64" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 1 yr, 24 hr Rainfall=2.97" Area (ac) CN Description Post Development 24 hr Rainfall=2.97' Printed 10/19/2020 1.950 98 0.890 61 >75% Grass cover, Good, HSG B 2.840 86 Weighted Average 0.890 31.34% Pervious Area 1.950 68.66% Impervious Area Tc Length 5.0 Description Direct Entry, Post Development Type 1124-hr 1 yr, Prepared by SHIMP ENGINEERING HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Subcatchment 3S: Onsite Untreated Runoff = 0.15 cfs @ 11.99 hrs, Volume= 0.009 af, Depth= 0.35" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 1 yr, 24 hr Rainfall=2.97" Area (ac) CN Description Post Development 24 hr Rainfall=2.97' Printed 10/19/2020 0.310 61 >75% Grass cover, Good, HSG B 0.003 98 Paved parking, HSG B 0.313 61 Weighted Average 0.310 99.04% Pervious Area 0.003 0.96% Impervious Area Tc Length 5.0 Description Direct Entry, Post Development Post Development Type 1124-hr 1 yr, 24 hr Rainfall=2.97' Prepared by SHIMP ENGINEERING Printed 10/19/2020 HydroCAD09.10 s/n 07054 ©2011 HvdroCAD Software Solutions LLC Paae 6 Summary for Subcatchment 4S: Offsite Untreated Runoff = 0.05 cfs @ 12.16 hrs, Volume= 0.006 af, Depth= 0.35" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 1 yr, 24 hr Rainfall=2.97" Area (ac) CN Description 0.210 61 >75% Grass cover, Good, HSG B 0.210 100.00% Pervious Area Tc Length i Description Direct Entry, Post Development Post Development Type 1124-hr 1 yr, 24 hr Rainfall=2.97' Prepared by SHIMP ENGINEERING Printed 10/19/2020 HydroCAD09.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 7 Summary for Pond 5P: StormTech Inflow Area = 3.170 ac, 62.15% Impervious, Inflow Depth = 1.50" for 1 yr, 24 hr event Inflow = 8.44 cfs @ 11.96 hrs, Volume= 0.397 of Outflow = 0.26 cfs @ 14.26 hrs, Volume= 0.397 af, Atten= 97%, Lag= 137.9 min Primary = 0.26 cfs @ 14.26 hrs, Volume= 0.397 of Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Peak Elev= 520.90' @ 14.26 hrs Surf.Area= 4,743 sf Storage= 9,583 cf Plug -Flow detention time= 427.4 min calculated for 0.397 of (100% of inflow) Center -of -Mass det. time= 427.6 min ( 1,251.9 - 824.3 ) Volume Invert Avail.Storage Storage Description #1 516.72' 919 cf 36.0" D x 130.01 Pipe Storage S= 0.0098 7' #2 517.50' 11,919 cf 47.46'W x 99.801 x 8.30'H STONE STORAGE 39,313 cf Overall - 9,515 cf Embedded = 29,798 cf x 40.0% Voids #3 519.50' 9,158 cf StormTech MC-4500 x 86 Inside #2 Effective Size= 90.4"W x 60.0"H => 26.46 sf x 4.031 = 106.5 cf Overall Size= 100.0"W x 60.0"H x 4.331 with 0.31' Overlap #4 519.50' 357 cf StormTech MC-4500 Cap x 10 Inside #2 Effective Size= 63.5"W x 59.0"H => 15.25 sf x 2.341 = 35.7 cf Overall Size= 90.2"W x 59.4"H x 2.92'L with 0.58' Overlap 22,353 cf Total Available Storage Device Routina Invert Outlet Devices #1 Primary 516.72' 24.0" Round Culvert L= 77.4' Ke= 0.600 Inlet / Outlet Invert= 516.72' / 516.10' S= 0.0080 '/' Cc= 0.900 n= 0.012 #2 Device 1 516.72' 2.2" Vert. Orifice/Grate-l-YR C= 0.600 #3 Device 1 521.40' 13.0" Vert. Orifice/Grate-10-YR C= 0.600 #4 Primary 523.40' Custom Weir/Orifice, Cv= 2.62 (C= 3.28) Head (feet) 0.00 2.00 Width (feet) 4.00 4.00 Primary OutFlow Max=0.26 cfs @ 14.26 hrs HW=520.90' (Free Discharge) 1- Culvert (Passes 0.26 cfs of 25.30 cfs potential flow) �2=Orifice/Grate-1-YR (Orifice Controls 0.26 cfs @ 9.74 fps) 3=Orifice/Grate-10-YR ( Controls 0.00 cfs) =Custom Weir/Orifice ( Controls 0.00 cfs) Post Development Post Development Type 1124-hr 1 yr, 24 hr Rainfall=2.97" Prepared by SHIMP ENGINEERING Printed 10/19/2020 Summary for Link 6L: POA Inflow Area = 3.693 ac, 53.43% Impervious, Inflow Depth = 1.34" for 1 yr, 24 hr event Inflow = 0.38 cfs @ 12.01 hrs, Volume= 0.413 of Primary = 0.38 cfs @ 12.01 hrs, Volume= 0.413 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Post Development Post Development Type 1124-hr 10 yr, 24 hr Rainfall=5.43" Prepared by SHIMP ENGINEERING Printed 10/19/2020 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Paae 9 Time span=0.00-48.00 hrs, dt=0.05 hrs, 961 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: Offshe Treated Runoff Area=0.330 ac 6.06% Impervious Runoff Depth=1.63" Tc=5.0 min CN=61 Runoff=0.95 cfs 0.045 of Subcatchment 2S: Onsite Treated Runoff Area=2.840 ac 68.66% Impervious Runoff Depth=3.87" Tc=5.0 min CN=86 Runoff=18.92 cfs 0.916 of Subcatchment 3S: Onsite Untreated Runoff Area=0.313 ac 0.96% Impervious Runoff Depth=1.63" Tc=5.0 min CN=61 Runoff=0.90 cfs 0.043 of Subcatchment 4S: Offshe Untreated Runoff Area=0.210 ac 0.00% Impervious Runoff Depth=1.63" Tc=18.0 min CN=61 Runoff=0.38 cfs 0.029 of Pond 5P: StormTech Peak Elev=523.56' Storage=17,801 cf Inflow=19.86 cfs 0.961 of Outflow=6.80 cfs 0.961 of Link 6L: POA Inflow=7.53 cfs 1.032 of Primary=7.53 cfs 1.032 of Total Runoff Area = 3.693 ac Runoff Volume = 1.032 of Average Runoff Depth = 3.35" 46.57% Pervious = 1.720 ac 53.43% Impervious = 1.973 ac Post Development Type 1124-hr 10 yr, Prepared by SHIMP ENGINEERING HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Subcatchment 1 S: Offsite Treated Runoff = 0.95 cfs @ 11.97 hrs, Volume= 0.045 af, Depth= 1.63" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 10 yr, 24 hr Rainfall=5.43" Area (ac) CN Description 0.190 61 >75% Grass cover, Good, HSG B 0.020 98 Paved parking, HSG B 0.330 61 Weighted Average 0.310 93.94% Pervious Area 0.020 6.06% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Post Development 24 hr Rainfall=5.43" Printed 10/19/2020 Post Development Type 1124-hr 10 yr, Prepared by SHIMP ENGINEERING HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: Onsite Treated Runoff = 18.92 cfs @ 11.95 hrs, Volume= 0.916 af, Depth= 3.87" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 10 yr, 24 hr Rainfall=5.43" Area (ac) CN Description Post Development 24 hr Rainfall=5.43" Printed 10/19/2020 1.950 98 0.890 61 >75% Grass cover, Good, HSG B 2.840 86 Weighted Average 0.890 31.34% Pervious Area 1.950 68.66% Impervious Area Tc Length 5.0 Description Direct Entry, Post Development Type 1124-hr 10 yr, Prepared by SHIMP ENGINEERING HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Subcatchment 3S: Onsite Untreated Runoff = 0.90 cfs @ 11.97 hrs, Volume= 0.043 af, Depth= 1.63" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 10 yr, 24 hr Rainfall=5.43" Area (ac) CN Description Post Development 24 hr Rainfall=5.43" Printed 10/19/2020 0.310 61 >75% Grass cover, Good, HSG B 0.003 98 Paved parking, HSG B 0.313 61 Weighted Average 0.310 99.04% Pervious Area 0.003 0.96% Impervious Area Tc Length 5.0 Description Direct Entry, Post Development Post Development Type 1124-hr 10 yr, 24 hr Rainfall=5.43" Prepared by SHIMP ENGINEERING Printed 10/19/2020 HydroCAD09.10 s/n 07054 ©2011 HvdroCAD Software Solutions LLC Paae 13 Summary for Subcatchment 4S: Offsite Untreated Runoff = 0.38 cfs @ 12.12 hrs, Volume= 0.029 af, Depth= 1.63" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 10 yr, 24 hr Rainfall=5.43" Area (ac) CN Description 0.210 61 >75% Grass cover, Good, HSG B 0.210 100.00% Pervious Area Tc Length i Description Direct Entry, Post Development Prepared by SHIMP ENGINEERING HvdroCAD® 9.10 s/n 07054 © 2011 Hvdn Type /124-hr 10 yr, Software Solutions LLC Summary for Pond 5P: StormTech Post Development 24 hr Rainfall=5.43" Printed 10/19/2020 Inflow Area = 3.170 ac, 62.15% Impervious, Inflow Depth = 3.64" for 10 yr, 24 hr event Inflow = 19.86 cfs @ 11.95 hrs, Volume= 0.961 of Outflow = 6.80 cfs @ 12.08 hrs, Volume= 0.961 af, Atten= 66%, Lag= 7.5 min Primary = 6.80 cfs @ 12.08 hrs, Volume= 0.961 of Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Peak Elev= 523.56' @ 12.08 hrs Surf.Area= 4,737 sf Storage= 17,801 cf Plug -Flow detention time= 301.5 min calculated for 0.960 of (100% of inflow) Center -of -Mass det. time= 302.1 min ( 1,102.5 - 800.3 ) Volume Invert Avail.Storage Storage Description #1 516.72' 919 cf 36.0" D x 130.01 Pipe Storage S= 0.0098 7' #2 517.50' 11,919 cf 47.46'W x 99.801 x 8.30'H STONE STORAGE 39,313 cf Overall - 9,515 cf Embedded = 29,798 cf x 40.0% Voids #3 519.50' 9,158 cf StormTech MC-4500 x 86 Inside #2 Effective Size= 90.4"W x 60.0"H => 26.46 sf x 4.031 = 106.5 cf Overall Size= 100.0"W x 60.0"H x 4.331 with 0.31' Overlap #4 519.50' 357 cf StormTech MC-4500 Cap x 10 Inside #2 Effective Size= 63.5"W x 59.0"H => 15.25 sf x 2.341 = 35.7 cf Overall Size= 90.2"W x 59.4"H x 2.92'L with 0.58' Overlap 22,353 cf Total Available Storage Device Routina Invert Outlet Devices #1 Primary 516.72' 24.0" Round Culvert L= 77.4' Ke= 0.600 Inlet / Outlet Invert= 516.72' / 516.10' S= 0.0080 '/' Cc= 0.900 n= 0.012 #2 Device 1 516.72' 2.2" Vert. Orifice/Grate-l-YR C= 0.600 #3 Device 1 521.40' 13.0" Vert. Orifice/Grate-10-YR C= 0.600 #4 Primary 523.40' Custom Weir/Orifice, Cv= 2.62 (C= 3.28) Head (feet) 0.00 2.00 Width (feet) 4.00 4.00 Primary OutFlow Max=6.65 cfs @ 12.08 hrs HW=523.54' (Free Discharge) 1- Culvert (Passes 5.95 cfs of 34.22 cfs potential flow) �2=Orifice/Grate-1-YR (Orifice Controls 0.33 cfs @ 12.49 fps) 3=Orifice/Grate-10-YR (Orifice Controls 5.62 cfs @ 6.09 fps) =Custom Weir/Orifice (Weir Controls 0.71 cfs @ 1.24 fps) Post Development Post Development Type 1124-hr 10 yr, 24 hr Rainfall=5.43" Prepared by SHIMP ENGINEERING Printed 10/19/2020 HydroCAD09.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 15 Summary for Link 6L: POA Inflow Area = 3.693 ac, 53.43% Impervious, Inflow Depth = 3.35" for 10 yr, 24 hr event Inflow = 7.53 cfs @ 12.07 hrs, Volume= 1.032 of Primary = 7.53 cfs @ 12.07 hrs, Volume= 1.032 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Post Development Post Development Type 1124-hr 100yr, 24 hr Rainfall=8.90" Prepared by SHIMP ENGINEERING Printed 10/19/2020 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Paae 16 Time span=0.00-48.00 hrs, dt=0.05 hrs, 961 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: Offshe Treated Runoff Area=0.330 ac 6.06% Impervious Runoff Depth=4.14" Tc=5.0 min CN=61 Runoff=2.46 cfs 0.114 of Subcatchment 2S: Onsite Treated Runoff Area=2.840 ac 68.66% Impervious Runoff Depth=7.21" Tc=5.0 min CN=86 Runoff=33.87 cfs 1.705 of Subcatchment 3S: Onsite Untreated Runoff Area=0.313 ac 0.96% Impervious Runoff Depth=4.14" Tc=5.0 min CN=61 Runoff=2.34 cfs 0.108 of Subcatchment 4S: Offshe Untreated Runoff Area=0.210 ac 0.00% Impervious Runoff Depth=4.14" Tc=18.0 min CN=61 Runoff=1.02 cfs 0.073 of Pond 5P: StormTech Peak Elev=525.02' Storage=20,873 cf Inflow=36.32 cfs 1.819 of Outflow=35.02 cfs 1.819 of Link 6L: POA Inflow=37.93 cfs 2.000 of Primary=37.93 cfs 2.000 of Total Runoff Area = 3.693 ac Runoff Volume = 2.000 of Average Runoff Depth = 6.50" 46.57% Pervious = 1.720 ac 53.43% Impervious = 1.973 ac Post Development Type 1124-hr 100yr, Prepared by SHIMP ENGINEERING HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Subcatchment 1 S: Offsite Treated Runoff = 2.46 cfs @ 11.96 hrs, Volume= 0.114 af, Depth= 4.14" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 100yr, 24 hr Rainfall=8.90" Area (ac) CN Description 0.190 61 >75% Grass cover, Good, HSG B 0.020 98 Paved parking, HSG B 0.330 61 Weighted Average 0.310 93.94% Pervious Area 0.020 6.06% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Post Development 24 hr Rainfall=8.90" Printed 10/19/2020 Post Development Type 1124-hr 100yr, Prepared by SHIMP ENGINEERING HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: Onsite Treated Runoff = 33.87 cfs @ 11.95 hrs, Volume= 1.705 af, Depth= 7.21" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 100yr, 24 hr Rainfall=8.90" Area (ac) CN Description Post Development 24 hr Rainfall=8.90" Printed 10/19/2020 1.950 98 0.890 61 >75% Grass cover, Good, HSG B 2.840 86 Weighted Average 0.890 31.34% Pervious Area 1.950 68.66% Impervious Area Tc Length 5.0 Description Direct Entry, Post Development Type 1124-hr 100yr, Prepared by SHIMP ENGINEERING HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Subcatchment 3S: Onsite Untreated Runoff = 2.34 cfs @ 11.96 hrs, Volume= 0.108 af, Depth= 4.14" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 100yr, 24 hr Rainfall=8.90" Area (ac) CN Description Post Development 24 hr Rainfall=8.90" Printed 10/19/2020 0.310 61 >75% Grass cover, Good, HSG B 0.003 98 Paved parking, HSG B 0.313 61 Weighted Average 0.310 99.04% Pervious Area 0.003 0.96% Impervious Area Tc Length 5.0 Description Direct Entry, Post Development Post Development Type 1124-hr 100yr, 24 hr Rainfall=8.90" Prepared by SHIMP ENGINEERING Printed 10/19/2020 HydroCAD09.10 s/n 07054 ©2011 HvdroCAD Software Solutions LLC Paae 20 Summary for Subcatchment 4S: Offsite Untreated Runoff = 1.02 cfs @ 12.11 hrs, Volume= 0.073 af, Depth= 4.14" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 100yr, 24 hr Rainfall=8.90" Area (ac) CN Description 0.210 61 >75% Grass cover, Good, HSG B 0.210 100.00% Pervious Area Tc Length i Description Direct Entry, Post Development Post Development Type 1124-hr 100yr, 24 hr Rainfall=8.90" Prepared by SHIMP ENGINEERING Printed 10/19/2020 HydroCAD09.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 21 Summary for Pond 5P: StormTech Inflow Area = 3.170 ac, 62.15% Impervious, Inflow Depth = 6.89" for 100yr, 24 hr event Inflow = 36.32 cfs @ 11.95 hrs, Volume= 1.819 of Outflow = 35.02 cfs @ 11.97 hrs, Volume= 1.819 af, Atten= 4%, Lag= 1.3 min Primary = 35.02 cfs @ 11.97 hrs, Volume= 1.819 of Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Peak Elev= 525.02' @ 11.97 hrs Surf.Area= 4,737 sf Storage= 20,873 cf Plug -Flow detention time= 187.6 min calculated for 1.818 of (100% of inflow) Center -of -Mass det. time= 188.4 min ( 971.9 - 783.5 ) Volume Invert Avail.Storage Storage Description #1 516.72' 919 cf 36.0" D x 130.01 Pipe Storage S= 0.0098 7' #2 517.50' 11,919 cf 47.46'W x 99.801 x 8.30'H STONE STORAGE 39,313 cf Overall - 9,515 cf Embedded = 29,798 cf x 40.0% Voids #3 519.50' 9,158 cf StormTech MC-4500 x 86 Inside #2 Effective Size= 90.4"W x 60.0"H => 26.46 sf x 4.031 = 106.5 cf Overall Size= 100.0"W x 60.0"H x 4.331 with 0.31' Overlap #4 519.50' 357 cf StormTech MC-4500 Cap x 10 Inside #2 Effective Size= 63.5"W x 59.0"H => 15.25 sf x 2.341 = 35.7 cf Overall Size= 90.2"W x 59.4"H x 2.92'L with 0.58' Overlap 22,353 cf Total Available Storage Device Routina Invert Outlet Devices #1 Primary 516.72' 24.0" Round Culvert L= 77.4' Ke= 0.600 Inlet / Outlet Invert= 516.72' / 516.10' S= 0.0080 '/' Cc= 0.900 n= 0.012 #2 Device 1 516.72' 2.2" Vert. Orifice/Grate-l-YR C= 0.600 #3 Device 1 521.40' 13.0" Vert. Orifice/Grate-10-YR C= 0.600 #4 Primary 523.40' Custom Weir/Orifice, Cv= 2.62 (C= 3.28) Head (feet) 0.00 2.00 Width (feet) 4.00 4.00 Primary OutFlow Max=33.57 cfs @ 11.97 hrs HW=524.96' (Free Discharge) 1- Culvert (Passes 8.07 cfs of 38.16 cfs potential flow) �2=Orifice/Grate-1-YR (Orifice Controls 0.36 cfs @ 13.74 fps) 3=Orifice/Grate-10-YR (Orifice Controls 7.71 cfs @ 8.36 fps) =Custom Weir/Orifice (Weir Controls 25.50 cfs @ 4.09 fps) Post Development Post Development Type 1124-hr 100yr, 24 hr Rainfall=8.90" Prepared by SHIMP ENGINEERING Printed 10/19/2020 Summary for Link 6L: POA Inflow Area = 3.693 ac, 53.43% Impervious, Inflow Depth = 6.50" for 100yr, 24 hr event Inflow = 37.93 cfs @ 11.97 hrs, Volume= 2.000 of Primary = 37.93 cfs @ 11.97 hrs, Volume= 2.000 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs PROFFIT ROAD TOWNHOMES SOUTH Area: I POA 24 Hr 1 year Storm: 1.LV = 0.13 = 0.12 lMaXQde,eloped = 0.41 cfs = 0.413 jQde..loped = 0.38 cfs Pre Development Post I Development 10 yr 1 7.611 7.53 PROFFIT ROAD TOWNHOMES SOUTH Time of Concentration Calculations PRE DEVELOPMENT TOC 100 ft Overland Flow 4.10% slope 0.35 C-value 1 10.9 min ISeelye Chart 484.0 ft S.C. Flow 2.25% slope 1.1 fps velocity 7.1 min. NEH Figure 15-4 0.0 ft Channel** 0.0 ft height 1 0.0 min. Kirpich Chart TOC=j 18.0 min. ** There is no Channel on site. All ToC's assumed to be 5 minutes. This assumption dictates very conservative design factors. TOC 5.0 MINUTES POST DEVELOPMENT (OFFSITE UNTREATED) TOC 36.0 ft Overland Flow 3.86% sloe 0.35 C-value 7.8 min ISeelye Chart 583.0 ft S.C. Flow 1.85% sloe 0.9 fps velocity I 10.2 min. INEH Figure 15-4 0.0 ft Channel** 0.0 ft height 1 0.0 1 min. I Kirpich Chart TOC=j 18.0 min. >- ere is no Uhannel on site. .1 v Roved y 0 z o .e 300 I— 7 IcZ.7T��: w u_ 200 Soil Poor Grass \SurfaceLLJ Average Grass 6 w U-,5 a x =_ y U Z 90 9 \ a SO Dense 70 Grass z \ N 60 \ J 0 50 V -� 40 x 30 z w J 20 m 35 30 F1 20 w F z_ z z 0.5 w _ w IA o 15 j 2.0 0 / a z o 5.0 z �- 10cr i 20 w 0. w OVERLAND FLOW TIME (Seelye Chart) z 10 U 0 9�w J z 7 V Source: Data Book for Civil Engineers. E.E. Seelye Plate 5-1 1.00 0.90 0.80 0.70 0.60 0.40 0.30 0.20 0.09 0. 0.08 0.07 0 0.06 n 0.05 0.04 0.03 0.02 0.01 0.005 0 2 ci ca v �q 19�i-oo ao c� w v c ctimao d d d d d ddd.: Velocity (ft(s) ' I 35 1 30 ' V i Poved 9 z 25 o .a 300 7 Bore v_ 0 20 w 200 Sod Poor \ Gross w U-.3 z \Surface < W Average ` z J 0.5 z w i I QO Bzense �- o W 0 1 5 W z _ 90, \ OR 2 N / / a 80 Grass \ a / ~ z z 5.0 10— 0V 20 oW. w V J 40 10 0 O U 30 9 W LU z I J ' 8 20 7 1 6 I OVERLAND FLOW TIME (Seelye Chart) Source: Data Book for Civil Engineers, E.E. Seelye 11m," �-1 SHIMPEN6INEERIY6, P. C. ENGINMIA'6-L4NDPLMff6-PRGIECPMANAGEWAT (434)227-5140 1.00 o.w 0180 0.;0 0.60 0.40 0.30 0.20 0.10 0.00 0.08 0.07 0 0.06 0.05 0.01 0.03 0.&2 0.01 0.005 C t- X 7 c 1 .. a 9� cc Q 0 r. ^ C C C O C 0 =G— Velocity (ft1m) PROFFIT ROAD TOWNHOMES SOUTH POST DEV OFFSITE UNTREATED TOC NOMOGRAPH REVISION DATE: 010119/2020 DESIGN OF OUTLET PROTECTION FROM A ROUND PIPE FLOWING FULL MINIMUM TAILWATER CONDITION (Tw � 0.5 DIAMETER) 30 Outlet j = Do + La Pipe 2 MiDiaeter, Da i La _N o' 60. T i water < 0.5Do `eP 5qQ FI li[ l�:i 4 illi �� I �! iiGililii 1111IW111l1R0I111DI111113yIVA!'[Hu�Il�rlPrrN�L�/r�YL�iiP.N111�MYlYIR�Htl1Y�lfmo 4 3 1L10 1000 PROFFIT ROAD TOWNHOMES SOUTH LD-204 Stormwater Inlet Computations Inlets on Grade Only Sag Inlets Only U rx U a o a a z 0 w c7 H A a° a a A c� v� 1 2 3 5 6 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 (ft) (ac) 1 (in/hr) (cfs) (cfs) (cfs) V) V) (ft) (ft) (cfs) (cfs) (ft) (ft) (ft) All DI-7 3.5 0.47 0.47 0.22 4.0 0.88 0.00 0.88 0.020 0.04 0.04 0.09 6.35 6.5 1.43 0.00 1.43 0.13 8.11 A8 DI-3B 12 0.58 0.82 0.47 4.0 1.89 0.00 1.89 0.020 0.02 0.03 5.05 0.23 100.0% 1.89 0.00 6.5 3.08 0.00 3.08 6.81 0.26 77.0% 2.37 0.71 A5 DI-313 12 0.73 0.71 0.51 4.0 2.05 0.00 2.05 0.020 0.08 0.02 0.02 0.26 0.5 0.53 6.88 6.5 3.33 0.71 4.04 0.32 0.5 0.64 9.67 A4 DI-3C 12 1.05 0.72 0.76 4.0 3.04 0.00 3.04 0.026 0.08 0.02 0.02 0.27 0.5 0.53 7.06 6.5 4.94 0.00 4.94 0.31 0.5 0.61 9.03 A9C DI-3C 6 0.33 0.70 0.23 4.0 0.92 0.00 0.92 0.026 0.08 0.02 0.02 0.12 0.5 0.24 1.45 6.5 j 1.49 j 0.00 j 1.49 1 0.17 0.5 0.33 2.00 PROFFIT ROAD TOWNHOMES SOUTH LD-229 STORM DRAIN DESIGN COMPUTATIONS From To Catch. Runoff Inc Accum ToC Total Total Up Do 1pipc Inv Pipe Pipe Velocity Flow time Point Point Area Coef AC AC Intensity Flow (cfs) invert Invert Length Slope Diameter Capacity Inc (ac) (min) (in/hr) El El (ft) % (in) (cfs) (ft/s) (min) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 All A10 0.47 0.47 0.22 5.00 5.17 1.14 529.00 526.50 53.04 471% 15 15.2 7.4 0.12 A10 A9 0.22 5.12 5.14 1.13 524.50 524.30 20.29 0.99% 15 7.2 4.3 0.08 A9C A913 0.33 0.70 023 0.23 5.08 5.15 1.18 527.37 526.76 88.36 0.69% 15 5.8 3.7 0.40 A913 A9A 0.23 5.40 5.07 1.17 526.56 526.10 66.21 0.69% 15 5.2 3.7 0.30 A9A A9 0.23 5.30 5.10 1.17 525.90 524.30 118.88 1.35% 15 7.9 5.3 0.37 A9 AS 0.45 5.37 5.08 2.28 524.10 523.70 53.27 075% 15 6.8 5.0 0.18 AS A7 U.N5 0.82 0.47 0.92 5.18 5.12 4.73 3.38% 0.05 Note, Detention System Between A7 & A6 A6 A5* 026% 36 A5 A4* 517.11 516.87 94.38 025% 36 A41-1 A4G 0.003 0.90 0.002 0.002 5.00 5.17 0.01 524.90 524.51 39.00 1-00% 6 0.2 0.5 1.26 A4G A4F 0.003 0.90 0.002 0.002 6.26 4.87 0.01 524.41 523.80 61 1-00% 6 0.2 0.5 1.97 A4F A4E 0.003 0.90 0.002 0.002 6.97 4.72 0.01 523.70 523.29 41 1-00% 6 0.2 0.5 1.32 A4E A4 0.002 0.002 6.32 4.86 0.01 523.19 522.90 29 1-00% 6 0.2 0.5 0.94 A4D A4C 0.003 0.90 0.002 0.002 5.00 5.17 0.01 524.90 524.51 39 1-00% 6 0.2 0.5 1.26 A4C A413 0.003 0.90 0.002 0.002 6.26 4.87 0.01 524.41 523.80 61 1.00% 6 0.2 0.5 1.97 A413 A4A 0.003 0.90 0.002 0.002 6.97 4.72 0.01 523.70 523.29 41 1.00% 6 0.2 0.5 1.32 A4A A4 0.002 0.002 6.32 4.86 0.01 523.19 522.88 31 100% 6 0.2 0.5 1.00 A4** A3 1.054 0.72 0.76 0.76 6.00 4.93 8.29 516.72 516.10 77.42 0.80% 24 21.9 6.5 0.20 A3** A2 0.76 520 5.12 8.29 515.90 514.00 267.25 0.71% 24 6.1 5.7 0.78 A2** Al 0.76 5.78 4.98 8.29 513.45 511.11 97.26 1 2.41% 24 38.0 9.7 Q04 *Pipe Sizing not computed as pipe is used for storage ** Q is the 10-yr Q from h drocad + the Accumilated AC = 7.53+0.76 =8.29 PROFFIT ROAD TOWNHOMES SOUTH LD-347 Hydraulic Grade Line n= 0.012 Structure Number (1) Water Surface Elev.' (2) Do (3) Qo (4) Lo (5) SF % (6) Hr (7) Junction Loss Final H (19) Water Surface Elev. (20) Rim. Elev (21) Vo (8) Ho (9) O; (10) V; (11) O;v; (12) H; (13) Angle (14) He (15) H, (16) 1.3-H, (17) 0.51-1r (18) A2 512.71 2.00 8.29 97.3 0.11 % 0.11 9.7 0.89 8.29 9.7 80.3 0.04 67 0.89 1.78 0.89 1.000 513.71 518.39 A3 515.60 2.00 8.29 267.3 0.11% 0.31 5.7 0.07 8.29 5.7 47.3 0.18 7 0.07 0.24 0.12 0.427 516.03 522.00 A4 517.70 2.00 8.29 77.4 0.11 % 0.09 6.5 0.02 8.29 6.5 53.8 0.23 0 0.02 0.25 0.12 0.213 517.91 525.77 A5' 519.27 3.00 7.53 94.4 0.01 % 0.01 7.5 0.31 7 53 7.5 56.5 0.31 30 0.31 0.61 0.31 0.316 519.59 A6- S19.61 3.00 7.53 34.9 0.01 % 0.00 7.5 0.38 7.5 56.5 0.31 33 0.38 0.75 0.98 0.49 1 0.492 1 520.- `A5 AND A6 ARE NOT INCLUDED IN THE HYDRAULICE GRADE DRAWING BECAUSE THEY ARE INSIDE THE DETENTION SYSTEM 'Outlet WSE is listed as the greater of either the calculated tailwater or the invert out. ' Estimated to be the same as the outflow from C1 for this submittal. 2 Estimated to be the same as the outflow from D1 for this submittal. K (14.5) Angle Check Height to Rim 67 OK 4.68 0.13 7 OK 5.97 0.03 0 OK 7.86 0.35 30 OK 7.69 0.43 33 OK 8.01 0.50 49 OK 4.64 0.61 69 OK 3.70 0.66 71 OK 4.49 0.70 90 OK 6.86 0.25 20 OK 6.37 0.70 90 OK 6.44 0.30 61 OK 3.97 PROFFIT ROAD TOWNHOMES SOUTH Modified LD-268 Roadside and Median Ditch Desi n Form Side Slope I Min Slope iVft I Max Slope ft/t I I I I I Earth I Protective Lining SCC C A CA TOC — :1 L — :1 R Design Storm Intensity (in/hr) a (cis) Allowable Velocity (fps) n=.03 EC-2 or EC-3: n=.05 Paved: n=.015 INCR ACC Vel.' On T Velocity' I Depth" On Depth 1 0.60 1.60 1 0.96 1 0.96 1 5 1 3 1 3 1 0.01 1 0.03 1 2-Yr 1 5.17 1 4.97 1 4 0.25 1 2.89 1 0.86 "NOTES: The SCC is temporary for this site and only necessary during E&S Phase 2 SHIMP ENGINEERING, P.C. Design Focused Engineering Water Quality Calculations: Pre -Development VRRM Landuse Map Post -Development VRRM Landuse Map VRRM Redevelopment Spreadsheets J LIMITS OF DISTURBANCE J USED AS BOUNDARY FOR WATER QUALITY IMPROVEMENTS AREA = 3.34 AC SIM PENGINEERING, P.C. EN6a'EE4a'G-LMF M10VG-PRGEUMAMAGE,409 a � ❑❑ u TMP 32-35 2.72 AC TURF (NO HATCH) --- ® 0.37 AC �c WOODS 0.25 AC IMPERVIOUS I I I I l 0 l l l l l 0 l l l l l I PROFFIT ROAD TOWNHOMES SOUTH PRE-DEVELOPEMENT VRRM LANDUSE MAP REVISION DATE: 10119/2020 0 1 1 1 9 1 1 1 1 11� 60 0 60 LEGEND IMPERVIOUS ® WOODS NOTE: ALL SOIL HAS HSG B 1 y 120 180 1 "=60' P O■ 1 O iI I I 0' 5TNITARY EASEMENT I oe s5m Rc wT � I I I I I I � I I SWITARY FAEENENT Po J96 _ I TMP 32-29D LEGEND _ IMPERVIOUS I NOTE: ALL SOIL HAS HSG B I ❑ I T -----------0 0---------- -- --- - LIMITS OF DISTURBANCE USED AS BOUNDARY FOR WATER QUALITY IMPROVEMENTS SIM PENGINEERING, P.C. EN6a'EE4a'G-LMF M10VG-PRGEUMAMAGE,409 0 i 00 7,j` HATCHED --k - IMPERVIOUS AR -� 1.90 AC -' r ALL ELSE TURF -, 1.44 AC I I I I O I I I I l O l l I I I I PROFFIT ROAD TOWNHOMES SOUTH POST DEVELOPEMENT VRRM LANDUSE MAP REVISION DATE: 10119/2020 TMP 32-35 60 0 60 120 180 1 "=60' DEq Virginia Runoff Reduction Method Re -Development Compliance Spreadsheet - Version 3.0 112011 BMP Standards and Specifications 02013 Draft BMP Standards and Specifications �- Project Name: Proffit South ® datainput cells Date: 7/8/2020 constant values Linear Development Project? No calculation cells Site Information Post -Development Project (Treatment Volume and Loads) Enter Total Disturbed Area (acres) 3.34 Check. BMP Desi n Spec' fcatians List: 2013 Draft Stds & Specs Linearproject? No ® Land cover areas entered correctly? ✓ F ® Total disturbed area entered? ✓ Pre-ReDevelopment Land Cover (acres) A Soils BSoils7SoilsDTotals Forest/Open Space (acres) - undisturbetl forest/open space 0.370.37 Manned Tuff lacres)-disturbed, graded for 2J2 yards or other brim be mowed/managed 2.72 Impervious Caver(acres) 02S 0.25 3.34 Post -Development Land Cover (acres) A soils BSoils CSoils DSoils Totals Forest/Open Space (acres) -- undisturbed, 0.00 space protected forest/openreforested land Manned Tuff (acres) graded for 1'� yards or other turf t0 be mowed/mana ed 1.40 Impervious Caver(acres) 1.90 1.90 Area Check OK. OK. OK. OK. 3.34 Constants Runoff Coefficients Rv Annual Rainfall (inches) 43 ASoils BSoils CSoils DSoils Target Rainfall Ecent(inches) 1.00 Forest/Open Space 0.02 0.03 0.00 0.05 Total Phosphorus (TP) EMC(mg/L) 0.26 ManagelTurf OAS 0.20 0.22 0.25 Total Nitrogen (TN) EMC(mg/L) 1.86 Impervious Cower 0.95 0.95 0.95 0.95 Target TP Load(lb/acre/yr) OA1 Pj(unitless correction factor) 0.90 LAND COVER SUMMARY -- PRE-REDEVELOPMENTr COVER SUMMARY POST DEVELOPMENT Land Cower SummorePre Lord Cover Summary-Pbst(Finnl) Land Cover Summarynaost Lomf Cover Summary -Post Pre-ReDecelopment Listed Adjusted' Post Rebev.&New Impervious PortAeDecelapment Post -Development New Impervious Forest/Open Space COcer(acres( 0.37 0.00 Forest/Open Space Forest/Open 0.00 Forrst/Open Space 0.00 Cower (acres) Weighted Rv(foresu 0.03 0.00 Weighted Rv(finesq 0.00 Weighted RvOorest) 0.00 %Forest 11% 0% %Forest 0% %Forest 0% Managed Turf Cover (acres) 2.72 144 Managed Turf Cover 149 Manegetl TurfCover 144 (acres) (acres) Weighted Rv(turf) 0.20 0.20 Weighted Far (turf) 0.20 Weighted RV Joel) 0.20 %Managed Turf 81% 85% %Manned Turf 43% %Managed Tuff 85% Impervious tower (acres) 0.25 0.25 lmpe(ares� 1.90 ReDec 025 Newlm'crvio s Geer 1.65 cover (acres)us Rv(imperaceas) 0.95 0.95 Rv(imperviaus) 0.95 W(imperviousl 0.95 Rv(impervious) 0.95 %Impervious 7% 15% %Impervious 57% %Impervious 15% Total She Area (acres) 3.34 1.69 Final Site Area (so.) 3.34 Total ReOev. She Area 169 (acres) She RV 0.24 0.31 Final Post Dee She Re 0.63 ReDev She IN 031 Treatment Volume and Nutrient Load Treatment Volume and Nutrient Load Port -Development Final pme Post-ReDevelopment Pre-ReOewelopmeM Treatment Volume 0.0661 0.0438 Development O.1144 Treabnece Volume 0.0438 Trentment Volunw 0.1306 (acre-ft) TrealmentVoluna, larre-kl (acre-k) (acre -fit) Port -Development Final Pan- postReDeeelopment Pre-ReOewelopment Treatment Volume 2,87J 1,908 Development 7,598 Treabnad Volume 1,908 Treatment Volume (cubic 5,690 (cubic feet) TrentmentVolume (arbk feet) feet) (cubic feet) PostAelievelopment Post -Development TP Pre-ReDevelopment TP Load Final Post- 1.91 1.20 Development TP Load 4.77 Wad (TP' 3.58 (lb/yr) (Ib/yr) (lb/yr)a Wad(lb/yr) FmReOevelopmen[lPLoatl peracre Final Part-0evelopment TP Post-ReDevelopment 1P (pmerelP am 0J1 Load per acre 1.49 Lord pe,art. (lb/ave/yr) (lb/acre/yr) Baseline TP Loatl (lb/yr) Maa Reduction Required (OAl lbs/ave/yr applied to pmreaevelopment area excluding pervious 0.69 (Below Pre M% land Proposed for new impervious cover) ReDevelopment Load) 'Adjusted Land Cower Summary: TP Load Reduction TP Load Reduction Pre ReDevelopment land cover minus pervious land rover Oorest/open spare or Required for 0.24 , Required for New 2.90 staged far aneogl Pmpasetlfarnew impervious rover. Redeveloped Area Impervious Area (lb/yr) (hope Adjusted total acreage is consistent with Past-RagavelapmeM acreage(minus acreage of an. impervious rover). Column I shawl Toad reduction rer urfementfor new impervious cover (based on new development bad limit, 0.41 f&A ne/ysar). Post -Development TP load Reduction Required (Ib/yr) 3.14 Nitrogen Loads (Informational Purposes Only) Final Pon -Development TN Load Pre-ReDewslopment TN Wad(lb/yr) 12.93 (Post-ReDerelopmett&New 34.15 Impervious) (lb/yr) Drainage Area A Drainage Area A Land Cover (acres) Land Cover A Soils BSoils CSoils DSoils Totals Rv Forest/Open Space (acres) 0.00 0.00 Managed Turf(acres) 0.88 0.88 0.20 Impervious Cover (acres) 1.86 1.86 0.95 Total Phosphorus Available for Removal in D.A. A (lb/yr) 4.43 Total 2.74 Post Development Treatment Volume in D.A. A (ft')i 7,053 Stormwater Best Management Practices (RR= Runoff Reduction) Runoff Managed Turf Impervious Volume from Runoff Remaining Total BMP Phosphorus Phosphorus Untreated Phosphorus Remaining Practice Reduction Credit Area Cover Credit Upstream Reduction Runoff Treatment Removal Load from Phosphorus Removed By Phosphoro Credit (%) (acres) Area (acres) practice (kal (ft) Volume fts ( ) Volume ka ( 1 Efficiency W (%) Upstream Load to Practice (lb) s Load (lb) 14. Manufactured Treatment Practices (lb) Practice (lb) 14.a. Manufactured Treatment Device- 0 0.88 1.86 0 0 7,053 7,053 40 0.00 4.43 1.77 2.66 Hydrodynamic TOTAL IMPERVIOUS COVER TREATED(ac) 1.86 AREACHECK:OK. TOTAL MANAGED TURF AREA TREATED(ac) 0.88 AREACHECK:OK. TOTAL PHOSPHORUS REMOVAL REQUIRED ON SITE (lb/yr) 3.14 TOTAL PHOSPHORUS AVAILABLE FOR REMOVAL IN D.A. A (lb/yr) 4.43 TOTAL PHOSPHORUS REMOVED WITHOUT RUNOFF REDUCTION PRACTICES IN D.A. A (lb/yr) 1.77 TOTAL PHOSPHORUS REMOVED WITH RUNOFF REDUCTION PRACTICES IN D.A. A (lb/yr) 0.00 TOTAL PHOSPHORUS LOAD REDUCTION ACHIEVED IN D.A. A (lb/yr) 1.77 TOTAL PHOSPHORUS REMAINING AFTER APPLYING BMP LOAD REDUCTIONS IN D.A. A (lb/yr) 2.66 SEE WATER QUALITY COMPLIANCE TAB FOR SITE COMPLIANCE CALCULATIONS NITROGEN REMOVED WITH RUNOFF REDUCTION PRACTICES IN D.A. A (Ib/yr) 0.00 NITROGEN REMOVED WITHOUT RUNOFF REDUCTION PRACTICES IN D.A. A (Ib/yr) 0.00 TOTAL NITROGEN REMOVED IN D.A. A (Ib/yr) 0.00 Site Results (Water Quality Compliance) Area Checks D.A. A D.A. B D.A. C D.A. D D.A. E AREA CHECK FOREST/OPEN SPACE (ac) 0.00 0.00 0.00 OK. IMPERVIOUS COVER (ac) 1.86 0.00 0.00 0.00 OK. IMPERVIOUS COVER TREATED (ac) 1.86 0.00 E0.00 0.00 T MANAGED TURF AREA (ac) 0.88 0.00 0.00 MANAGED TURF AREA TREATED (ac) 0.88 0.00 0.00 0.00 OK. AREA CHECK Site Treatment Volume (ft3) 7,s96 Runoff Reduction Volume and TP By Drainage Area D.A. A D.A. B D.A. C D.A. D D.A. E TOTAL RUNOFF REDUCTION VOLUME ACHIEVED (ft) 0 1 0 0 0 0 TP LOAD AVAILABLE FOR REMOVAL (Ib/yr) 4.43 0.00 0.00 0.00 0.00 4.43 TP LOAD REDUCTION ACHIEVED (Ib/yr) 1.77 0.00 0.00 0.00 0.00 1.77 TP LOAD REMAINING (Ib/yr) 2.66 0.00 0.00 0.00 0.00 2.66 NITROGEN LOAD REDUCTION ACHIEVED (Ib/yr) D.00 0.00 0.00 0.00 0.00 0.00 Total Phosphorus FINAL POST-DEVELOPMENTTP LOAD(Ib/yr) 4.77 TP LOAD REDUCTION REQUIRED (Ib/yr) 3.14 TP LOAD REDUCTION ACHIEVED (Ib/yr) 1.77 TP LOAD REMAINING (Ib/yr): 3.00 REMAINING TP LOAD REDUCTION REQUIRED (Ib/yr): 1.37 Total Nitrogen (For Information Purposes) POST -DEVELOPMENT LOAD(Ib/yr) 1 34.15 NITROGEN LOAD REDUCTION ACHIEVED (Ib/yr) 0.00 REMAINING POST -DEVELOPMENT NITROGEN LOAD (Ib/yr) 34.15 SHIMP ENGINEERING, P.C. Design Focused Engineering Independent Reports: Excerpt from NRCS Soils Report NOAA Precipitation Report USDA United States Department of Agriculture MRCS Natural Resources Conservation Service A product of the National Cooperative Soil Survey, a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local participants Custom Soil Resource Report for Albemarle County, Virginia November 1 2019 Soil Map The soil map section includes the soil map for the defined area of interest, a list of soil map units on the map and extent of each map unit, and cartographic symbols displayed on the map. Also presented are various metadata about data used to produce the map, and a description of each soil map unit. M' 7W N 3 TWN Custom Soil Resource Report N Soil Map N N fn T25010 7250G0 725= 72510D 7251M 72510D 725190 DI 3 3 q iF p Map Smie:1:1,270 rn5' Ded m A pDbat(8.x 1175bBt q N Meters 0 15 30 W 9D A0 50 700 Z00 3r Mapproedb:WebMammr Cmc rdnz�:WGSB4 Edgdrs:UTMZm17NWGS84 6 A n Y I I 3 7'WN MAPLEGEND Area of Interest (AOQ O Area of Interest (AOI) Solis Soil Map Unit Polygons N Soil Map Unit Lines Soil Map Unit Points Special Point Features V Blowout ® Borrow Pit Clay Spot O Closed Depression Gravel Pit Gravelly Spot O Landfill A. Lava Flow Marsh or swamp Mine or Quarry O Miscellaneous Water O Perennial Water y Rock Outcrop + Saline Spot Sandy Spot Severely Eroded Spot Q Sinkhole Slide or Slip J, Sodic Spot Custom Soil Resource Report MAP INFORMATION g Spoil Area The soil surveys that comprise your AOI were mapped at 1:15,800. o Stony Spot W Very Stony Spot Warning: Soil Map may not be valid at this scale. wet Spot Enlargement of maps beyond the scale of mapping can cause Other misunderstanding of the detail of mapping and accuracy of soil Special Line Features line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed Water Features scale. Streams and Canals Transportation Please rely on the bar scale on each map sheet for map �..ry Rails measurements. N Interstate Highways Source of Map: Natural Resources Conservation Service ti US Routes Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Major Roads Local Roads Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts Background distance and area. A projection that preserves area, such as the . Aerial Photography Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Albemarle County, Virginia Survey Area Data: Version 13, Sep 17, 2019 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: May 20, 2019—Aug 1, 2019 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. V1 Custom Soil Resource Report Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 27B Elioak loam, 2 to 7 percent slopes 4.0 100.0% Totals for Area of Interest 4.0 100.0% Map Unit Descriptions The map units delineated on the detailed soil maps in a soil survey represent the soils or miscellaneous areas in the survey area. The map unit descriptions, along with the maps, can be used to determine the composition and properties of a unit. A map unit delineation on a soil map represents an area dominated by one or more major kinds of soil or miscellaneous areas. A map unit is identified and named according to the taxonomic classification of the dominant soils. Within a taxonomic class there are precisely defined limits for the properties of the soils. On the landscape, however, the soils are natural phenomena, and they have the characteristic variability of all natural phenomena. Thus, the range of some observed properties may extend beyond the limits defined for a taxonomic Gass. Areas of soils of a single taxonomic class rarely, if ever, can be mapped without including areas of other taxonomic classes. Consequently, every map unit is made up of the soils or miscellaneous areas for which it is named and some minor components that belong to taxonomic classes other than those of the major soils. Most minor soils have properties similar to those of the dominant soil or soils in the map unit, and thus they do not affect use and management. These are called noncentrasting, or similar, components. They may or may not be mentioned in a particular map unit description. Other minor components, however, have properties and behavioral characteristics divergent enough to affect use or to require different management. These are called contrasting, or dissimilar, components. They generally are in small areas and could not be mapped separately because of the scale used. Some small areas of strongly contrasting soils or miscellaneous areas are identified by a special symbol on the maps. If included in the database for a given area, the contrasting minor components are identified in the map unit descriptions along with some characteristics of each. A few areas of minor components may not have been observed, and consequently they are not mentioned in the descriptions, especially where the pattern was so complex that it was impractical to make enough observations to identify all the soils and miscellaneous areas on the landscape. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The objective of mapping is not to delineate pure taxonomic classes but rather to separate the landscape into landforms or landform segments that have similar use and management requirements. The delineation of such segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, however, onsite investigation is needed to define and locate the soils and miscellaneous areas. R9 Custom Soil Resource Report An identifying symbol precedes the map unit name in the map unit descriptions. Each description includes general facts about the unit and gives important soil properties and qualities. Soils that have profiles that are almost alike make up a soil series. Except for differences in texture of the surface layer, all the soils of a series have major horizons that are similar in composition, thickness, and arrangement. Soils of one series can differ in texture of the surface layer, slope, stoniness, salinity, degree of erosion, and other characteristics that affect their use. On the basis of such differences, a soil series is divided into soil phases. Most of the areas shown on the detailed soil maps are phases of soil series. The name of a soil phase commonly indicates a feature that affects use or management. For example, Alpha silt loam, 0 to 2 percent slopes, is a phase of the Alpha series. Some map units are made up of two or more major soils or miscellaneous areas. These map units are complexes, associations, or undifferentiated groups. A complex consists of two or more soils or miscellaneous areas in such an intricate pattern or in such small areas that they cannot be shown separately on the maps. The pattern and proportion of the soils or miscellaneous areas are somewhat similar in all areas. Alpha -Beta complex, 0 to 6 percent slopes, is an example. An association is made up of two or more geographically associated soils or miscellaneous areas that are shown as one unit on the maps. Because of present or anticipated uses of the map units in the survey area, it was not considered practical or necessary to map the soils or miscellaneous areas separately. The pattern and relative proportion of the soils or miscellaneous areas are somewhat similar. Alpha -Beta association, 0 to 2 percent slopes, is an example. An undifferentiated group is made up of two or more soils or miscellaneous areas that could be mapped individually but are mapped as one unit because similar interpretations can be made for use and management. The pattern and proportion of the soils or miscellaneous areas in a mapped area are not uniform. An area can be made up of only one of the major soils or miscellaneous areas, or it can be made up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example. Some surveys include miscellaneous areas. Such areas have little or no soil material and support little or no vegetation. Rock outcrop is an example. W Custom Soil Resource Report Albemarle County, Virginia 2713—Elioak loam, 2 to 7 percent slopes Map Unit Setting National map unit symbol: kb8y Mean annual precipitation: 25 to 65 inches Mean annual air temperature: 54 to 59 degrees F Frost -free period: 195 to 231 days Farmland classification: All areas are prime farmland Map Unit Composition Elioak and similar soils: 80 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Elioak Setting Landform: Hillslopes Landform position (two-dimensional): Summit Landform position (three-dimensional): Interfluve Down -slope shape: Convex Across -slope shape: Convex Parent material: Residuum weathered from mica schist Typical profile H1 - 0 to 8 inches: loam H2 - 8 to 39 inches: silty clay H3 - 39 to 79 inches: silt loam Properties and qualities Slope: 2 to 7 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Well drained Runoff class: Medium Capacity of the most limiting layer to transmit water (Ksat): Moderately high to high (0.20 to 1.98 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: Moderate (about 6.6 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 2e Hydrologic Soil Group: B Hydric soil rating: No 10 11/112019 Precipitation Frequency Data Server NOAA Atlas 14, Volume 2, Version 3 Location name: Charlottesville, Virginia, USA* E ,.. Latitude: 38.1309°, Longitude:-78.4283° FW�WI Elevation: 538.71 ft** " source: ESRI Maps "" source: USGS POINT PRECIPITATION FREQUENCY ESTIMATES G.M. Bonin, D. Martin, B. Lin, T. Parzybok, M.Yekta, and D. Riley NOAA, National Weather Service, Silver Spring, Maryland PF tabular I PF graphical I Maps & aerials PF tabular PDS-based point precipitation frequency estimates with 90% confidence intervals (in inches)1 Average recurrence interval (years) Duration 7 2 5 10 25 50 1 100 00 200 500 1000 0.349 F 0.416 F 0.489 F 0.551 F 0.621 F 0.677 F 0.729 F 0.778 F 0.839 F 0.889 5-min (0 315-0.386) (0.376-0.461) (0.441-0.541) (0.495-0.609) (0.556-0.685) (0.603-0.745) (0.645-0.802) (0.694-0.858) (0.730-0.928) (0.78-0.986) 10-min (g_503-0617) (0.602-0 38) (0.707-0866) (0.79-0.974) (0.886---11.09) (0.960-18.19) (1.03127) (1.09-21336) (1. 5-3L47) (1214.55) 0.697 0.837 0.991 1.11 1.25 1.36 1.46 1.56 1.67 1.76 15-min (0.629-0.772) (0.756-0.928) (0.894-1.10) 1 (1.00-1.23) 1 (1.12-1.38) 1 (1.22-1.50) 1 (1.30-1.61) 1 (1.37-1.72) 1 (1.45-1.85) 1 (1.51-1.95) 0.955 1.16 1.41 1.61 1.86 2.06 2.24 2.42 2.66 2.85 30-min (0.862-1.06) 1 (1.05-1.28) 1 (1.27-1.56) 1 (1.45-1.79) 1 (1.66-2.05) 1 (1.83-2.26) 1 (1.99-2.47) 1 (2.13-2.67) 1 (2.31-2.94) (2.45-3.16) 1.19 1.45 1.81 2.10 2.48 2.78 3.09 3.40 3.82 4.15 60-min (1.08-1.32) 1 (1.31-1.61) 1 (1.63-2.00) 1 (1.89-2.32) 1 (2.22-2.73) 1 (2.48-3.07) 1 (2.74-3.40) 1 (2.99-3.75) 1 (3.32-4.22) 1 (3.58-4.61) 1.43 1.74 2.18 2.56 3.06 3.47 3.90 4.35 4.99 5.52 2-hr (1.27-1.62) 1 (1.54-1.97) 1 (1.93-2.46) 1 (2.27-2.88) 1 (2.69-3.43) 1 (3.04-3.90) 1 (3.39-4.38) 1 (3.75-4.89) 1 (4.25-5.61) 1 (4.8-6.23) 1.57 1.90 2.38 2.79 3.33 3.79 4.27 4.77 5.47 6.07 3-hr (1.38-1.79) 1 (1.67-2.17) 1 (2.09-2.71) 1 (2.45-3.18) 1 (2.91-3.79) 1 (3.29-4.30) 1 (3.68-4.84) 1 (4.07-5.41) 1 (4.61-6.22) 1 (5.D6-6.91) 1.99 2.41 2.99 3.52 4.23 4.86 5.52 6.23 7.26 8.17 6-hr (1.77-2.26) 1 (2.13-2.74) 1 (2.64-3.39) (3.09-3.99) (3.69-4.80) (4.21-5.49) (4.73-6.24) (5.29-7.05) (6.07-8.22) (6.73-9.26) 2.49 3.01 3.75 4.44 5.40 6.26 7.20 8.23 9.76 11.1 12-hr (2.21-2.85) 1 (2.66-3.44) 1 (3.31-4.29) (3.90-5.06) (4.70-6.14) (5.40-7.11) (6.13-8.17) (6.91-9.33) (8.04-11.1) (9.02-12.7) 2997 3.60 4.60 5.43 6.67 7.73 8.90 10.2 12.1 13.8 24-hr (2.67-3.35) (3.23-4.05) (4.11-5.17) (4.84-6.10) (5.91-7.47) (6.80-8.64) (7.76-9.93) (8.79-11.3) (10.3-13.5) (11.5-15.3) 2-day (3. 6391) (3. 3-4.74) (4.85 6002) (5. 8--374.07) (6.86 8?57) (7. 3 9684) (8.86- 12) (9.97- 2.7) (115315.0) (12.t8-16.9) 3.73 4.52 5.74 6.74 8.20 9.41 10.7 12.2 14.2 16.0 3-day (3.39-4.14) 1 (4.10-5.01) 1 (5.20-6.36) 1 (6.09-7.46) 1 (7.36-9.06) 1 (8.40-10.4) 1 (9.50-11.9) 1 (10.7-13.4) 1 (12.4-15.8) 1 (13.7-17.8) 3.96 4.79 6.08 7.15 8.68 9.97 11.4 12.9 15.0 16.9 4-day (3.62-4.37) 1 (4.38-5.29) 1 (5.55-6.71) 1 (6.50-7.86) 1 (7.86-9.54) 1 (8.97-11.0) 1 (10.1-12.5) 1 (11.4-14.1) 1 (13.2-16.6) 1 (14.6-18.7) 4.60 5.54 6.92 8.06 9.69 11.0 12.5 14.1 16.3 18.2 7-day (4.21-5.05) 1 (5.07-6.07) 1 (6.33-7.59) 1 (7.35-8.83) 1 (8.79-10.6) 1 (9.97-12.1) 1 (11.2-13.7) 1 (12.5-15.4) 1 (14.3-17.9) 1 (15.8-20.0) 5.22 6.27 7.73 B.93 10.6 12.0 13.4 15.0 17.1 18.9 10day (4.80-5.68) (5.77-6.81) (7.11-8.40) (8.19-9.69) (9.69-11.5) (10.9-13.0) (12.1-14.6) (13.4-16.3) (15.2-18.7) (16.6-20.7) 6.86 8.19 9.89 11.2 13.0 14.5 15.9 17.4 19.4 21.0 20-0ay P� (6.41-7.38) (7.65-8.80) (9.22-10.6) (10.4-12.0) (12.1-14.0) (13.4-15.5) (14.7-17.1) (15.9-18.7) (17.7-20.9) (19.0-22.7) 8.42 9.98 11.8 13.2 15.0 16.4 17.7 19.0 20.8 22.1 30rlay (7.91-8.99) 1 (9.38-10.7) 1 (11.1-12.6) 1 (12.4-14.1) 1 (14.0-16.0) 1 (15.3-17.5) 1 (16.5-18.9) 1 (17.6-20.3) 1 (19.1-22.3) 1 (20.2-23.7) 22.4 IF 45tlay (9.91---11.2) (11.172--13.2) (13.14 5.4) (15..1---17.0) (17.10-19.2) (18.t4- 0.8) (196�2.3) (20.9- 3.8) (2244 5.8) (2325-27.2) 12.4 14.5 16.8 18.4 20.6 22.1 23.6 25.0 26.8 28.1 BOrlay (11.7-13.1) (13.7-15.4) (15.8-17.7) (17.4-19.5) (19.4-21.7) (20.8-23.4) (22.2-25.0) (23.5-26.5) (25.0-28.4) (26.1-29.9) 1 Precipitation frequency (PF) estimates in this table are based on frequency analysis of partial duration series (PDS). Numbers in parenthesis are PF estimates at lower and upper bounds of the 90% confidence interval. The probability that precipitation frequency estimates (for a given duration and average recurrence interval) will be greater than the upper bound (or less than the lower bound) is 5%. Estimates at upper bounds are not checked against probable maximum precipitation (PMP) estimates and may be higher than currently valid PMP values. Please refer to NOAA Atlas 14 document for more information. Back to Top hftps://hdsc.nws.noaa.gov/hdsolpfds/pfds_Printpage.html?lat=38.1309&Ion=-78.4283&data=depth&units=english&series=pds 1/4