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WPO201900057 Calculations WPO VSMP
SHIMPROJECT MANAGEMENT CIVIL ENGINEERING , LAND PLANNING ENGINEERING' January 22, 2020 Cox J /rI�fv1MP iA" Engineering Review 83LC.Emil Department of Community Development .,. 401 McIntire Road Charlottesville, VA 22902 _ { SICWAL V Regarding: WPO 201900057 Proffit Rd Town homes North VSMP — SWM Calculation Packet Dear Emily, Enclosed is the stormwater calculation packet for Proffit Rd Townhomes North. The development property has an area of 7.59 acres and a disturbed area of 5.60 acres. The project is a private redevelopment of a site. The proposed stormwater design meets water quality requirements set forth in 9VAC25-870-65 and water quantity requirements set forth in 9VAC25-870-66-B(3) and 9VAC25-870-66-C. SWM Quality SWM Quality is satisfied by providing required nutrient treatment for the development. 9VAC25-870-65 requires that the total phosphorous (TP) nutrient load created by the site development be treated in accordance with the VRRM Redevelopment Spreadsheet reduction requirements. To achieve nutrient treatment, a purchase of nutrient credits for the full amount of required treatment shall be made. This amount totals 4.98 lbs/yr phosphorous credits and satisfies the nutrient treatment requirement. As part of the site water quality requirements, 0.40 acres of the development's open space shall be dedicated as VRRM compliant SWM Forest/Open Space held in perpetuity in a vegetated state. This shall be dedicated with the Subdivision Plat for this development. Treatment Required Total Phosphorous) Treatment Provided Total Phosphorous) 4.98 Ib/yr 4.98 Ib/yr SWM Quantity SWM Quantity is satisfied by analyzing concentrated runoff from the development at a Point Of Analysis (POA) within a natural channel at the downstream edge of the development property. 9VAC25-870-66-B(3) requires that concentrated runoff from development at the POA meet the energy balance equation. To achieve this, most concentrated runoff from the site will be routed to an underground detention facility which discharges to POA. The runoff from the detention, along with unmanaged (bypass) runoff for the site, meets the energy balance equation. 9VAC25-870-66-C requires that the post-dev 10-year runoff at this POA not exceed the pre-dev 10-yr runoff. This condition has also been satisfied. Pre-dev Peak Runoff Max. Allowed Peak Runoff Post-dev Peak Runoff 1-Yr 0.61 cfs 0.42 cfs 0.40 cfs 10-Yr 9.52 cfs 9.52 cfs 9.08 cfs 100-Yr 29.15 cfs - 54.31 cfs Onsite Portion of Channel Analysis To further ensure the site protects the onsite channel area, we analyzed the runoff to the onsite portion of the channel, starting at the outfall of the new 36" culvert. At this portion, the Post -development runoff meets the energy balance equation (EBE). Due to this, no further analysis of the onsite portion of the channel is required (although regulations do not require that the EBE be met at this point — satisfying the EBE satisfies all channel analysis requirements at points of concentrated runoff.) This also stands because no other concentrated runoff is added to the existing channel until POA 1, which was analyzed above. Pre-dev Peak Runoff Max. Allowed Peak Runoff Post-dev Peak Runoff 1 •Yr 0.46 cfs 0.46 cfs 0.38 cfs 10-Yr 7.13 cfs 7.13 cfs 3.98 cfs If you have any questions about this calculation packet please do not hesitate to contact me at: keane(a)shimp- engineering.com or by phone at 434-299-9843. Keane Rucker, EIT Shimp Engineering, PC Contents: Water Quality Calculations: Pre-Dev VRRM Land Cover Map Post-Dev VRRM Land Cover Map VRRM Redevelopment Spreadsheet Water Quantity Calculations: Pre-Dev Drainage Map Post-Dev BMP Drainage Map Pre-Dev Channel Map Post-Dev Channel Map Predev HydroCAD Report Postdev HydroCAD Report Post-Dev Inlet Drainage Map VDOT LD-204 Inlet Capacity VDOT LD-229 Storm Drain Capacity VDOT LD-268 Ditch Capacity ESCP Calculations: Sediment Basin Design Spreadsheet Sediment Basin Design Nomographs Independent Reports: Excerpt from NRCS Soils Report NOAA Precipitation Report Water Quality Calculations: Pre-Dev VRRM Land Cover Map Post-Dev VRRM Land Cover Map VRRM Redevelopment Spreadsheet W PROFFIT RD TH NORTH PREDEV 2 -�� I ►MT' TOTAL SITE: 7.59 AC ALL HSG B WOODS: 7.09 AC TURF: 0.28 AC IMPERV: 0.22 LEGEND: WOODS TURF IMPERVIOUS i 80 0 80 160 240 ' Scale: 1 "=80' 5 W W W W W W W W W W W W LL LL W W �/�1 1Wl WWW W W W W W W W W Y W W W W W W W W W W W W W W W W W W W C1/•��j W W W W W W L Y W y Y W W W .l W W W W W V W LL LL W W W W W W W W W W M M Y W W Y Y W W W W W Y W W 1rV' 1p'V! J' W W W W W W 4 W W Y y W W W Y W W W W W W W W V W W W W W W W W W W W W W W W W W V W W W W W W W W W v W W W W W W W W W \ ± y y s W W W W W W W W W W W Y W W V e W W W W W W W W W W W LL LL W a LOT W W W W v 22 a LOT 21 LOT LO? 29 I9T toT LOOT 2 OT LOT 25 L. OT 23 'ITT LOT LOT LOT 47 L_� OT L. 49 LOT =a LOT ROAD C to D ,oT 8 _ ,5 'OT m tOT 12 LOT f LOT m LOT 9 Lor 8 IM � PROFFIT RD TH NORTH POSTDEV VRRM MAP TOTAL SITE: 7.59 AC ALL HSG B WOODS: 0.40 AC TURF: 4.39 AC IMPERV: 2.80 AC NOTE: FOR VRRM CALCS, ONLY AREAS THAT WILL BE PLACED WITHIN A SWM FOREST/OPEN SPACE EASEMENT ARE CLAIMED AS WOODS. LEGEND: WOODS 0 Ad TURF IMPERVIOUS 80 0 80 160 240 ' Scale: 1 "=80' 6 Project Name: Proffitt Rd TH North Date: 11/18/2019 Linear Development Project? No Information Project (Treatment Volume and Loads) Enter Total Disturbed Area (acres) Land Cover b.d, .. . I 7.59 ( Post -Development Land Cover (acres) �. .. .. .. .. canes .,.,a r„ewl.le.... ID data input cells Rnal resuhs Check. SMP Design Specifications List: 2013 Draft Stds & Specs Linear project? No Land cover areas entered correctly? ./ Total disturbed area entered? Land Cover Summary -Pre land Cover Summary-Post/Final) land Cover Summary -Past _Land Cover Summery -Post Pre-ReDevelopment Listed Adjusted' Post ReDev.&New Impervious Port-Itt- 1ppment Postdae I,uient N•w lmpervi forest/Open Space Cover lanes) 7.09 4,51 Forest/Open Space Cove° 040 Forcst/Open Spacr T 0,40 (acres) [over lacrezl Weighted Rvllorestl OM003 Weighted Rv(forezt) 0.03 Weighted Rv(foreztl 0.03 %Forest 93% 901,4 %Forest 5% %Farcst 8% Managed Tud Cover(acres 0.28 0,28 Managed Tuff Cover (acres) 439 Managed Turf Cpve� (acres) 4.39 Weighted Rv(tulf) 0.20 0.20 Weighted Rv(tud) 0,20 Weighted Rv(turf) 0,20 %Managed Turf 4% 6% %Managed Tuff 58% %Managed Turf 88% Impervious Cover (acresl 0,22 0.22 Impervious Cover (acresl 2.80 ReDev. Impervious 022 New Impervious Cover Cgver(acresl (acres) Rvlimpervious) 0.95 0.95 Rv(imperv,ous) 0.95 Rv(impervious 0,95 Rvlimperviousl %Impervious 3% 4% %Impervious 37% %Impervious 4% Total Site Area (acres) 7.59 5.01 Final Site Arca (acresl 7.59 Total ReDev. Site Area 5.01 ave ls) site Rv 0.06 0.08 Final Pout Dev Site Rv OA7 ( ReDev Site Rv 0.22 Treatment Volume and Nutrient Load Treatment Voiume and Nutrient Load Prc-ReDevelopment Treatment Volume Final Post -Development Post-ReDevelopment Post -Development Ixrc-k) 0.0398 0.0334 Treatment Volume 0.2958 Treatment Volume 0.0916 Treatment Volume 0.2043 lane-nl (acre-ft) (acre-ft) Prc-ReDevelopment Trexment Volume Final Post -Development Post-ReDevelopment Post-Develppment (cubic feet) 1,734 1,453 Trcannent Volume 12,887 Treatment Volume 3,989 Treat ment Volume(cubic 8,897 I<ubic Neq (cubic het) feet) Pre-ReDevelopmem TP Load Flnal Post' -------------- ! Pont#aDevelopment 3.09 pb/W) 0.91 Development TP Load 8.30 Load ITP) 2.51 Port Development TP Load 5.59 pb/yr) Ob/vrl' IIb/vrl .�„ Pre-ReDevebpment TY mad perxrc Final Past-Oewlopmen[Tn re (lb/xrcM) ana o1g mae perm L07 mad pt'._ am Ob/•v/nl ab/eve/n) Basel, ne TP load (lb/yr) Max.R�uctbn (0.411W/am/y pplied w pr-ed-1,Ipmentae epeipz 2.05 rgtequired z% Nnd -pod for w Imrvocor ReDevelopment Lead) 4Ciusred L-1 cov[r I-— "I. Reaeveropmenl Igrti mverminus Pervious lantl cover (JnresUopen spp<e ormongged TP Load Reduction Required for TP load Reduction Ilfj-ul proposedfornewimpervinus cover. Redeveloped Area OAS Required for New 6.53 Ob/yr) Impervious Area (Ib/yr) �diusted -111c 1191, is conslscent with Pnst-ReDevelopment gcreoge (minus pereoge of ew impervious cover). a Redunion below new development load limitation not required 11-11 Vh- loud reduc[ian requitement for new impervious [over (6osetl on new evelopmenrlrmd limn, 0 ui �bs�oc,<�yerrrl TP Load Reduction Required (1b/yr) 1 4.98 Water Quantity Calculations: Pre-Dev Drainage Map Post-Dev BMP Drainage Map Pre-Dev Channel Map Post-Dev Channel Map Predev HydroCAD Report Postdev HydroCAD Report Post-Dev Inlet Drainage Map VDOT LD-204 Inlet Capacity VDOT LD-229 Storm Drain Capacity VDOT LD-268 Ditch Capacity I 1 1 I ; � \ •�: \ � SV — 1 \\\\\, l / ' ' � MI 1 % r ♦ ` � `\ I', � ` \K / �,' / ' / , ` 4 1 / 'h` — 5 ""��➢➢ � \ """ VVVI 1 ` \\ \`\ \\I lJlyJ,I�, / / / / / / , / t ♦ I ; / I peel I \ ' / j II / J — � / � �j" �' i i' i� °""> �1 i \I ♦ I " I`I 1 1 � II e�,1\ \e ly 1 ME 1 � PROFFIT RD TH NORTH PREDEV - "-- POA DRAINAGE - -- _ --�- MAP - --_-_- :a--` -_-"-------_°-- ' ------------ PREDEV DRAINAGE AREA TO POA 1: 6.06 AC ' ---' ALL HSG B / WOODS: 5.89 AC TURF: 0.10 AC / IMPERV: 0.07 I / I 1 uw /^- I I \1 M � 11111 1 I 1 1 n11 W: / 80 0 80 160 240 ' Scale: 1 LEGEND: WOODS TURF IMPERVIOUS TO C POA DA 9 --------- - \ --- __ i 80 0 80 160 240 1�4 I Scale: 1 "=80' PROFFIT RD TH NORTH POSTDEV POA DRAINAGE MAP TOTAL DRAINAGE TO POA 1: 7.06 AC. INCLUDES DRAINAGE TO BMP AND BYPASS DRAINAGE. ALL HSG B BMP DRAINAGE AREA: 4.05 AC TOTAL TURF: 1.42 AC IMPERV: 2.63 AC TOC: ASSUMED 5.0 MIN. BYPASS DRAINAGE AREA: 3.01 AC TOTAL WOODS: 2.50 AC TURF: 0.39 AC IMPERV: 0.12 TOC: 13.2 MIN (PATH SHOWN) LEGEND: WOODS 0�0, 00 00 TURF IMPERVIOUS TOC BMP DA BYPASS DA �,�,` iff Energy Balance Equation Summary Proffit Rd TH North 24 Hr 1 year Storm Comparison: Qdeveloped I.F. *(Qpre-developed*RVPre-Developed)/RVdeveloped developed5 (Qforested *RVforested)/RVdeveloped POA 1: Qpre-developed = 0.61 RVPre-Developed = 0.087 Max Qdeveloped = 0.42 cfs RVDeveloped = 0.102 Achieved Post-Dev Peak Runoff Qlyr = 0.40 cfs. Site complies with 9VAC25-870-66-(3)A 10-YEAR STORM: Qpre=9.52 cfs Qpost=9.08 cfs Energy Balance Equation Summary for Onsite Channel Proffit Rd TH North 24 Hr 1 year Storm Comparison: Qdeveloped I.F. *(Qpre-developed* RVPre- Developed)/RVdeve loped developed (Qforested* RVforested)/RVdeveloped ONSITE PORTION OF CHANNEL AFTER CULVERT: Qpre-developed = 0.46 RVPre-Developed = 0.065 Max Qdeveloped = 0.46 cfs RVDeveloped = 0.049 Achieved Post-Dev Peak Runoff Qlyr = 0.38 cfs. Site complies with 9VAC25-870-66-(3)A 10-YEAR STORM: Qpre=7.13 cfs Qpost=3.98 cfs III PROFFIT RD TH NORTH PREDEV CHANNEL DRAINAGE MAP PREDEV DRAINAGE AREA TO CHANNEL: 4.54 AC ALL HSG B WOODS: 4.37 AC TURF: 0.10 AC IMPERV: 0.07 TOC ASSUMED TO BE THE SAME AS POA 1 / I / / I / I , LEGEND: WOODS TURF IMPERVIOUS TOC •�1 80 0 80 160 240 ' Scale: 1 "=80' IM Energy Balance Equation Summary for Onsite Channel Proffit Rd TH North 24 Hr 1 year Storm Comparison: Qdeveloped:5 I.F. *(Qpre-developed*RVPre- Developed)/RVdeveloped developed Qforested* RVforested)RVdeve loped ONSITE PORTION OF CHANNEL AFTER CULVERT: Qpre-developed = 0.46 RVPre-Developed = 0.065 Max Qdeveloped = 0.46 cis RVDeveloped = 0.049 Achieved Post-Dev Peak Runoff Qlyr = 0.38 cis. Site complies with 9VAC25-870-66-(3)A 10-YEAR STORM: Qpre=7.13 cis Qpost=3.98 cis 13 u R 9 OT OT - LOT LOT .LOT LOT LOT 5 LOT S6 OT t 1 � - LOT , LOT 58 -------- _—� 1 C--___- 0 80 160 240 Scale: 1 "=80' PROFFIT RD TH NORTH POSTDEV CHANNEL DRAINAGE MAP POSTDEV DRAINAGE AREA TO CHANNEL: 2.23 AC ALL HSG B WOODS: 1.72 AC TURF: 0.39 AC IMPERV: 0.12 TOC ASSUMED TO BE THE SAME AS POA 1 LEGEND: WOODS TURF IMPERVIOUS TOC BMP DA BYPASS DA 14 is ONSITE TO POA 1 Subcat Reach on Link 2S PREDEV ONSITE TO CHANNEL 15 Pre-Dev PREDEV Type // 24-hr 1-YR Rainfall=2.97' Prepared by Shimp Engineering, P.C. Printed 11/26/2019 HydroCAD89.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 2 Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1 S: ONSITE TO POA 1 Runoff Area=6.060 ac 0.00% Impervious Runoff Depth>0.17" Tc=13.0 min CN=56 Runoff=0.61 cfs 0.087 of Subcatchment 2S: PREDEV ONSITE TO Runoff Area=4.540 ac 0.00% Impervious Runoff Depth>0.17" Tc=13.0 min CN=56 Runoff=0.46 cfs 0.065 of Total Runoff Area=10.600 ac Runoff Volume = 0.151 of Average Runoff Depth = 0.17" 100.00% Pervious=10.600 ac 0.00% Impervious = 0.000 ac 16 Pre-Dev Type // 24-hr 1-YR Rainfall=2.97' Prepared by Shimp Engineering, P.C. Printed 11/26/2019 HydroCADO 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Page 3 Summary for Subcatchment 1 S: ONSITE TO POA 1 Runoff = 0.61 cfs @ 12.12 hrs, Volume= 0.087 af, Depth> 0.17" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type 11 24-hr 1-YR Rainfall=2.97" Area (ac) CN Description 5.890 55 Woods, Good, HSG B 0.070 91 Impervious 0.100 61 >75% Grass cover, Good, HSG B 6.060 56 Weighted Average 6.060 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 13.0 Direct Entry, 17 Pre-Dev PREDEV Type // 24-hr 1-YR Rainfall=2.97' Prepared by Shimp Engineering, P.C. Printed 11/26/2019 HydroCAD® 9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 4 Summary for Subcatchment 2S: PREDEV ONSITE TO CHANNEL Runoff = 0.46 cfs @ 12.12 hrs, Volume= 0.065 af, Depth> 0.17" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 1-YR Rainfall=2.97" Area (ac) CN Description 4.370 55 Woods, Good, HSG B 0.070 91 Impervious 0.100 61 >75% Grass cover, Good, HSG B 4.540 56 Weighted Average 4.540 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 13.0 Direct Entry, 18 Pre-Dev PREDEV Type 1124-hr 10-YR Rainfall=5.43" Prepared by Shimp Engineering, P.C. Printed 11/26/2019 HydroCAD® 9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 5 Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: ONSITE TO POA 1 Runoff Area=6.060 ac 0.00% Impervious Runoff Depth>1.12" Tc=13.0 min CN=56 Runoff=9.52 cfs 0.567 of Subcatchment 2S: PREDEV ONSITE TO Runoff Area=4.540 ac 0.00% Impervious Runoff Depth>1.12" Tc=13.0 min CN=56 Runoff=7.13 cfs 0.425 of Total Runoff Area = 10.600 ac Runoff Volume = 0.992 of Average Runoff Depth = 1.12" 100.00% Pervious =10.600 ac 0.00% Impervious = 0.000 ac 19 Pre-Dev PREDEV Type 11 24-hr 10-YR Rainfall=5.43" Prepared by Shimp Engineering, P.C. Printed 11/26/2019 HydroCAD® 9.10 s/n 07054 02011 HydroCAD Software Solutions LLC Page 6 Summary for Subcatchment 1 S: ONSITE TO POA 1 Runoff = 9.52 cfs @ 12.07 hrs, Volume= 0.567 af, Depth> 1.12" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10-YR Rainfall=5.43" Area (ac) CN Description 5.890 55 Woods, Good, HSG B 0.070 91 Impervious 0.100 61 >75% Grass cover, Good, HSG B 6.060 56 Weighted Average 6.060 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 13.0 Direct Entry, 20 Pre-Dev PREDEV Type // 24-hr 10-YR Rainfall=5.43" Prepared by Shimp Engineering, P.C. Printed 11/26/2019 HydroCAD® 9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 7 Summary for Subcatchment 2S: PREDEV ONSITE TO CHANNEL Runoff = 7.13 cfs @ 12.07 hrs, Volume= 0.425 af, Depth> 1.12" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10-YR Rainfall=5.43" Area (ac) CN Description 4.370 55 Woods, Good, HSG B 0.070 91 Impervious 0.100 61 >75% Grass cover, Good, HSG B 4.540 56 Weighted Average 4.540 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 13.0 Direct Entry, 21 Pre-Dev PREDEV Type // 24-hr 100-YR Rainfall=8.90" Prepared by Shimp Engineering, P.C. Printed 11/26/2019 HydroCAD® 9.10 s/n 07054 02011 HydroCAD Software Solutions LLC Page 8 Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: ONSITE TO POA 1 Runoff Area=6.060 ac 0.00% Impervious Runoff Depth>3.21" Tc=13.0 min CN=56 Runoff=29.15 cfs 1.622 of Subcatchment 2S: PREDEV ONSITE TO Runoff Area=4.540 ac 0.00% Impervious Runoff Depth>3.21" Tc=13.0 min CN=56 Runoff=21.84 cfs 1.215 of Total Runoff Area=10.600 ac Runoff Volume = 2.838 of Average Runoff Depth = 3.21" 100.00% Pervious=10.600 ac 0.00% Impervious = 0.000 ac 22 Pre-Dev PREDEV Type 11 24-hr 100-YR Rainfall=8.90" Prepared by Shimp Engineering, P.C. Printed 11/26/2019 HydroCAD® 9.10 s/n 07054 02011 HydroCAD Software Solutions LLC Page 9 Summary for Subcatchment 1 S: ONSITE TO POA 1 Runoff = 29.15 cfs @ 12.06 hrs, Volume= 1.622 af, Depth> 3.21" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 100-YR Rainfall=8.90" Area (ac) CN Description 5.890 55 Woods, Good, HSG B 0.070 91 Impervious 0.100 61 >75% Grass cover, Good, HSG B 6.060 56 Weighted Average 6.060 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 13.0 Direct Entry, 23 Pre-Dev PREDEV Type 11 24-hr 100-YR Rainfall=8.90" Prepared by Shimp Engineering, P.C. Printed 11/26/2019 HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Page 10 Summary for Subcatchment 2S: PREDEV ONSITE TO CHANNEL Runoff = 21.84 cfs @ 12.06 hrs, Volume= 1.215 af, Depth> 3.21" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 100-YR Rainfall=8.90" Area (ac) CN Description 4.370 55 Woods, Good, HSG B 0.070 91 Impervious 0.100 61 >75% Grass cover, Good, HSG B 4.540 56 Weighted Average 4.540 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 13.0 Direct Entry, 24 3S ONSITE (5S POSTDEV ONSITE TO CHANNEL BY ASS Subcat Reach on Link tP SITE TO ENTION 42P UN ERGROUND ETENTION 4L POA 1 25 Post-Dev POSTDEV Type // 24-hr 1-YR Rainfall=2.97' Prepared by Shimp Engineering, P.C. Printed 1/21/2020 HydroCADO 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Page 2 Time span=5.00-48.00 hrs, dt=0.05 hrs, 861 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: ONSITE TO DETENTION Runoff Area=4.050 ac 64.94% Impervious Runoff Depth=1.56" Tc=5.0 min CN=85 Runoff=11.35 cfs 0.528 of Pond 2P: UNDERGROUND DETENTION Peak Elev=502.54' Storage=0.494 of Inflow=11.35 cfs 0.528 of Outflow=0.12 cfs 0.043 of Subcatchment 3S: ONSITE BYPASS Runoff Area=3.010 ac 3.99% Impervious Runoff Depth=0.24" Tc=13.2 min CN=57 Runoff=0.40 cfs 0.059 of Link 4L: POA 1 Inflow=0.40 cfs 0.102 of Primary=0.40 cfs 0.102 of Subcatchment 5S: POSTDEV ONSITE TO Runoff Area=2.230 ac 5.38% Impervious Runoff Depth=0.26" Tc=13.2 min CN=58 Runoff=0.38 cfs 0.049 of Total Runoff Area = 9.290 ac Runoff Volume = 0.636 of Average Runoff Depth = 0.82" 69.11% Pervious = 6.420 ac 30.89% Impervious = 2.870 ac 26 Post-Dev POSTDEV Type // 24-hr 1-YR Rainfall=2.97' Prepared by Shimp Engineering, P.C. Printed 1/21/2020 HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Paqe 3 Summary for Subcatchment 1 S: ONSITE TO DETENTION Runoff = 11.35 cfs @ 11.96 hrs, Volume= 0.528 af, Depth= 1.56" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Type 11 24-hr 1-YR Rainfall=2.97" Area (ac) CN Description 2.630 98 IMPERVIOUS 1.420 61 >75% Grass cover, Good, HSG B 4.050 85 Weighted Average 1.420 35.06% Pervious Area 2.630 64.94% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, 27 Post-Dev POSTDEV Type // 24-hr 1-YR Rainfall=2.97' Prepared by Shimp Engineering, P.C. Printed 1/21/2020 HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Page 4 Summary for Pond 2P: UNDERGROUND DETENTION Inflow Area = 4.050 ac, 64.94% Impervious, Inflow Depth = 1.56" for 1-YR event Inflow = 11.35 cfs @ 11.96 hrs, Volume= 0.528 of Outflow = 0.12 cfs @ 22.63 hrs, Volume= 0.043 af, Atten= 99%, Lag= 640.3 min Primary = 0.12 cfs @ 22.63 hrs, Volume= 0.043 of Routing by Stor-Ind method, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Peak Elev= 502.54' @ 22.63 hrs Surf.Area= 0.126 ac Storage= 0.494 of Plug -Flow detention time= 720.0 min calculated for 0.043 of (8% of inflow) Center -of -Mass det. time= 551.0 min ( 1,376.4 - 825.4 ) Volume Invert Avail.Storage Storage Description #1 497.00' 0.301 of 15.00'W x 73.001 x 11.00'H STONE STORAGE x 5 1.383 of Overall - 0.631 of Embedded = 0.752 of x 40.0% Voids #2 497.00' 0.631 of 120.0" D x 70.01 Pipe Storage x 5 Inside #1 0.932 of Total Available Storage Device Routing Invert Outlet Devices #1 Primary 497.00' 24.0" Round Culvert L= 19.6' Ke= 0.600 Inlet / Outlet Invert= 497.00' / 495.00' S= 0.1020 '/' Cc= 0.900 n= 0.012 #2 Device 1 502.45' 14.0" W x 7.0" H Vert. Orifice/Grate C= 0.600 #3 Device 1 505.00' 8.0' long x 2.00' rise Sharp -Crested Rectangular Weir 2 End Contraction(s) 8.0' Crest Height Primary OutFlow Max=0.11 cfs @ 22.63 hrs HW=502.54' (Free Discharge) L1=Culvert (Passes 0.11 cfs of 30.23 cfs potential flow) 1:3=Sharp-Crested 2=Orifice/Grate (Orifice Controls 0.11 cfs @ 0.98 fps) Rectangular Weir ( Controls 0.00 cfs) 28 Post-Dev POSTDEV Type // 24-hr 1-YR Rainfall=2.97' Prepared by Shimp Engineering, P.C. Printed 1/21/2020 HydroCADO 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Page 5 Summary for Subcatchment 3S: ONSITE BYPASS Runoff = 0.40 cfs @ 12.12 hrs, Volume= 0.059 af, Depth= 0.24" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 1-YR Rainfall=2.97" Area (ac) CN Description 0.390 61 >75% Grass cover, Good, HSG B 0.120 98 Impervious 2.500 55 Woods, Good, HSG B 3.010 57 Weighted Average 2.890 96.01 % Pervious Area 0.120 3.99% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 13.2 Direct Entry, 29 POSTDEV Post-Dev Type // 24-hr 1-YR Rainfall=2.97' Prepared by Shimp Engineering, P.C. Printed 1/21/2020 HydroCAD® 9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 6 Summary for Link 4L: POA 1 Inflow Area = 7.060 ac, 38.95% Impervious, Inflow Depth = 0.17" for 1-YR event Inflow = 0.40 cfs @ 12.12 hrs, Volume= 0.102 of Primary = 0.40 cfs @ 12.12 hrs, Volume= 0.102 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs 30 Post-Dev POSTDEV Type 1124-hr 1-YR Rainfall=2.97' Prepared by Shimp Engineering, P.C. Printed 1/21/2020 HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Page 7 Summary for Subcatchment 5S: POSTDEV ONSITE TO CHANNEL Runoff = 0.38 cfs @ 12.11 hrs, Volume= 0.049 af, Depth= 0.26" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Type 11 24-hr 1-YR Rainfall=2.97" Area (ac) CN Description 0.390 61 >75% Grass cover, Good, HSG B 0.120 98 Impervious 1.720 55 Woods, Good, HSG B 2.230 58 Weighted Average 2.110 94.62% Pervious Area 0.120 5.38% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 13.2 Direct Entry, M POSTDEV Post-Dev Type // 24-hr 10-YR Rainfall=5.43" Prepared by Shimp Engineering, P.C. Printed 1/21/2020 HydroCAD® 9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 8 Time span=5.00-48.00 hrs, dt=0.05 hrs, 861 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: ONSITE TO DETENTION Runoff Area=4.050 ac 64.94% Impervious Runoff Depth=3.77" Tc=5.0 min CN=85 Runoff=26.42 cfs 1.272 of Pond 2P: UNDERGROUND DETENTION Peak Elev=504.43' Storage=0.675 of Inflow=26.42 cfs 1.272 of Outflow=4.25 cfs 0.787 of Subcatchment 3S: ONSITE BYPASS Runoff Area=3.010 ac 3.99% Impervious Runoff Depth=1.34" Tc=13.2 min CN=57 Runoff=5.03 cfs 0.336 of Link 4L: POA 1 Inflow=9.08 cfs 1.123 of Primary=9.08 cfs 1.123 of Subcatchment 5S: POSTDEV ONSITE TO Runoff Area=2.230 ac 5.38% Impervious Runoff Depth=1.41" Tc=13.2 min CN=58 Runoff=3.98 cfs 0.263 of Total Runoff Area = 9.290 ac Runoff Volume = 1.870 of Average Runoff Depth = 2.42" 69.11 % Pervious = 6.420 ac 30.89% Impervious = 2.870 ac 32 Post-Dev POSTDEV Type 1124-hr 10-YR Rainfall=5.43" Prepared by Shimp Engineering, P.C. Printed 1/21/2020 HydroCAD® 9.10 s/n 07054 02011 HydroCAD Software Solutions LLC Page 9 Summary for Subcatchment 1 S: ONSITE TO DETENTION Runoff = 26.42 cfs @ 11.95 hrs, Volume= 1.272 af, Depth= 3.77" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 10-YR Rainfall=5.43" Area (ac) CN Description 2.630 98 IMPERVIOUS 1.420 61 >75% Grass cover, Good, HSG B 4.050 85 Weighted Average 1.420 35.06% Pervious Area 2.630 64.94% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, 33 Post-Dev POSTDEV Type // 24-hr 10-YR Rainfall=5.43" Prepared by Shimp Engineering, P.C. Printed 1/21/2020 HydroCAD@ 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Page 10 Summary for Pond 2P: UNDERGROUND DETENTION Inflow Area = 4.050 ac, 64.94% Impervious, Inflow Depth = 3.77" for 10-YR event Inflow = 26.42 cfs @ 11.95 hrs, Volume= 1.272 of Outflow = 4.25 cfs @ 12.16 hrs, Volume= 0.787 af, Atten= 84%, Lag= 12.1 min Primary = 4.25 cfs @ 12.16 hrs, Volume= 0.787 of Routing by Stor-Ind method, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Peak Elev= 504.43' @ 12.16 hrs Surf.Area= 0.126 ac Storage= 0.675 of Plug -Flow detention time= 215.5 min calculated for 0.787 of (62% of inflow) Center -of -Mass det. time= 109.7 min ( 910.0 - 800.3 ) Volume Invert Avail.Storage Storage Description #1 497.00' 0.301 of 15.00'W x 73.001 x 11.00'H STONE STORAGE x 5 1.383 of Overall - 0.631 of Embedded = 0.752 of x 40.0% Voids #2 497.00' 0.631 of 120.0" D x 70.0'L Pipe Storage x 5 Inside #1 0.932 of Total Available Storage Device Routing Invert Outlet Devices #1 Primary 497.00' 24.0" Round Culvert L= 19.6' Ke= 0.600 Inlet / Outlet Invert= 497.00' / 495.00' S= 0.1020 '/' Cc= 0.900 n= 0.012 #2 Device 1 502.45' 14.0" W x 7.0" H Vert. Orifice/Grate C= 0.600 #3 Device 1 505.00' 8.0' long x 2.00' rise Sharp -Crested Rectangular Weir 2 End Contraction(s) 8.0' Crest Height Primary OutFlow Max=4.25 cfs @ 12.16 hrs HW=504.43' (Free Discharge) 't-1-Culvert (Passes 4.25 cfs of 35.96 cfs potential flow) 1:2=Orifice/Grate (Orifice Controls 4.25 cfs @ 6.25 fps) 3=Sharp-Crested Rectangular Weir ( Controls 0.00 cfs) 34 Post-Dev POSTDEV Type 1124-hr 10-YR Rainfall=5.43" Prepared by Shimp Engineering, P.C. Printed 1/21/2020 HydroCADO 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Page 11 Summary for Subcatchment 3S: ONSITE BYPASS Runoff = 5.03 cfs @ 12.07 hrs, Volume= 0.336 af, Depth= 1.34" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 10-YR Rainfall=5.43" Area (ac) CN Description 0.390 61 >75% Grass cover, Good, HSG B 0.120 98 Impervious 2.500 55 Woods, Good, HSG B 3.010 57 Weighted Average 2.890 96.01 % Pervious Area 0.120 3.99% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 13.2 Direct Entry, 35 Post-Dev POSTDEV Type 1124-hr 10-YR Rainfall=5.43" Prepared by Shimp Engineering, P.C. Printed 1/21/2020 HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Page 12 Summary for Link 4L: POA 1 Inflow Area = 7.060 ac, 38.95% Impervious, Inflow Depth = 1.91" for 10-YR event Inflow = 9.08 cfs @ 12.08 hrs, Volume= 1.123 of Primary = 9.08 cfs @ 12.08 hrs, Volume= 1.123 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs 36 Post-Dev POSTDEV Type 1124-hr 10-YR Rainfall=5.43" Prepared by Shimp Engineering, P.C. Printed 1/21/2020 HydroCAD® 9.10 s/n 07054 © 2011 HVdroCAD Software Solutions LLC Page 13 Summary for Subcatchment 5S: POSTDEV ONSITE TO CHANNEL Runoff = 3.98 cfs @ 12.07 hrs, Volume= 0.263 af, Depth= 1.41" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 10-YR Rainfall=5.43" Area (ac) CN Description 0.390 61 >75% Grass cover, Good, HSG B 0.120 98 Impervious 1.720 55 Woods, Good, HSG B 2.230 58 Weighted Average 2.110 94.62% Pervious Area 0.120 5.38% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 13.2 Direct Entry, 37 Post-Dev POSTDEV Type // 24-hr 100-YR Rainfall=8.90" Prepared by Shimp Engineering, P.C. Printed 1/21/2020 HydroCADS 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Page 14 Time span=5.00-48.00 hrs, dt=0.05 hrs, 861 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: ONSITE TO DETENTION Runoff Area=4.050 ac 64.94% Impervious Runoff Depth>7.07" Tc=5.0 min CN=85 Runoff=47.79 cfs 2.385 of Pond 2P: UNDERGROUND DETENTION Peak Elev=506.52' Storage=0.851 of Inflow=47.79 cfs 2.385 of Outflow=41.96 cfs 1.900 of Subcatchment 3S: ONSITE BYPASS Runoff Area=3.010 ac 3.99% Impervious Runoff Depth=3.66" Tc=13.2 min CN=57 Runoff=14.91 cfs 0.918 of Link 4L: POA 1 Inflow=54.31 cfs 2.817 of Primary=54.31 cfs 2.817 of Subcatchment 5S: POSTDEV ONSITE TO Runoff Area=2.230 ac 5.38% Impervious Runoff Depth=3.78" Tc=13.2 min CN=58 Runoff=11.44 cfs 0.702 of Total Runoff Area = 9.290 ac Runoff Volume = 4.004 of Average Runoff Depth = 5.17" 69.11% Pervious = 6.420 ac 30.89% Impervious = 2.870 ac 38 Post-Dev POSTDEV Type // 24-hr 100-YR Rainfall=8.90" Prepared by Shimp Engineering, P.C. Printed 1/21/2020 HydroCAD® 9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 15 Summary for Subcatchment 1 S: ONSITE TO DETENTION Runoff = 47.79 cfs @ 11.95 hrs, Volume= 2.385 af, Depth> 7.07" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 100-YR Rainfall=8.90" Area (ac) CN Description 2.630 98 IMPERVIOUS 1.420 61 >75% Grass cover, Good, HSG B 4.050 85 Weighted Average 1.420 35.06% Pervious Area 2.630 64.94% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, 39 Post-Dev POSTDEV Type 11 24-hr 100-YR Rainfall=8.90" Prepared by Shimp Engineering, P.C. Printed 1/21/2020 HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Page 16 Summary for Pond 2P: UNDERGROUND DETENTION Inflow Area = 4.050 ac, 64.94% Impervious, Inflow Depth > 7.07" for 100-YR event Inflow = 47.79 cfs @ 11.95 hrs, Volume= 2.385 of Outflow = 41.96 cfs @ 11.98 hrs, Volume= 1.900 af, Atten= 12%, Lag= 1.6 min Primary = 41.96 cfs @ 11.98 hrs, Volume= 1.900 of Routing by Stor-Ind method, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Peak Elev= 506.52' @ 11.99 hrs Surf.Area= 0.126 ac Storage= 0.851 of Plug -Flow detention time= 147.6 min calculated for 1.897 of (80% of inflow) Center -of -Mass det. time= 67.8 min ( 851.9 - 784.1 ) Volume Invert Avail.Storage Storage Description #1 497.00' 0.301 of 15.00'W x 73.001 x 11.00'H STONE STORAGE x 5 1.383 of Overall - 0.631 of Embedded = 0.752 of x 40.0% Voids #2 497.00' 0.631 of 120.0" D x 70.01 Pipe Storage x 5 Inside #1 0.932 of Total Available Storage Device Routing Invert Outlet Devices #1 Primary 497.00' 24.0" Round Culvert L= 19.6' Ke= 0.600 Inlet / Outlet Invert= 497.00' / 495.00' S= 0.1020 '/' Cc= 0.900 n= 0.012 #2 Device 1 502.45' 14.0" W x 7.0" H Vert. Orifice/Grate C= 0.600 #3 Device 1 505.00' 8.0' long x 2.00' rise Sharp -Crested Rectangular Weir 2 End Contraction(s) 8.0' Crest Height Primary OutFlow Max=41.20 cfs @ 11.98 hrs HW=506.44' (Free Discharge) t-1=Culvert (Inlet Controls 41.20 cfs @ 13.11 fps) L2=Orifice/Grate (Passes < 6.30 cfs potential flow) 3=Sharp-Crested Rectangular Weir (Passes < 44.47 cfs potential flow) 40 Post-Dev POSTDEV Type // 24-hr 100-YR Rainfall=8.90" Prepared by Shimp Engineering, P.C. Printed 1/21/2020 HydroCADO 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Page 17 Summary for Subcatchment 3S: ONSITE BYPASS Runoff = 14.91 cfs @ 12.06 hrs, Volume= 0.918 af, Depth= 3.66" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 100-YR Rainfall=8.90" Area (ac) CN Description 0.390 61 >75% Grass cover, Good, HSG B 0.120 98 Impervious 2.500 55 Woods, Good, HSG B 3.010 57 Weighted Average 2.890 96.01 % Pervious Area 0.120 3.99% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 13.2 Direct Entry, 41 Post-Dev POSTDEV Type 1124-hr 100-YR Rainfall=8.90" Prepared by Shimp Engineering, P.C. Printed 1/21/2020 HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Page 18 Summary for Link 4L: POA 1 Inflow Area = 7.060 ac, 38.95% Impervious, Inflow Depth = 4.79" for 100-YR event Inflow = 54.31 cfs @ 12.00 hrs, Volume= 2.817 of Primary = 54.31 cfs @ 12.00 hrs, Volume= 2.817 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs 42 Post-Dev POSTDEV Type // 24-hr 100-YR Rainfall=8.90" Prepared by Shimp Engineering, P.C. Printed 1/21/2020 HydroCAD® 9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 19 Summary for Subcatchment 5S: POSTDEV ONSITE TO CHANNEL Runoff = 11.44 cfs @ 12.06 hrs, Volume= 0.702 af, Depth= 3.78" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 100-YR Rainfall=8.90" Area (ac) CN Description 0.390 61 >75% Grass cover, Good, HSG B 0.120 98 Impervious 1.720 55 Woods, Good, HSG B 2.230 58 Weighted Average 2.110 94.62% Pervious Area 0.120 5.38% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 13.2 Direct Entry, 43 — ` \. ``'♦, 1 1 I ,\ ti 1 i \ \ 1 i i j I t / 1 I 1 \♦l`` / t t ; L 1 1\ 1 It 1 1 1 1 I 1 I \ -_ 11 \ I I \ //Q `♦ 1\ "i `y, `, \\ \t \5 1 15 `y 1 1 1 `\ L\ `\y `\--------- - _ \\ `\\� -~_-•• � _ � ` -- ,. ♦ { '1 y, \ \ \ 1 11 � \\ \\ L, 1, � '\ , _ _ -.".� � \ - _ _ ' `ly - \\\` �`'♦y�`y 7 1i �`tLLt\ 1, 1 \L 1 I 1, \ \\ \, `y \\ ------- - -..- ��� ' '' `y ♦\ �,\y\ T'� 5 I ._ ` ` i \ ` \ --- —----s1D— '1\5 \ \\ y \ \ \ -.__---- 111 I i 5 S : 1 1. l ` \ ♦ ♦ � \� "-.,.._ "__-__ "__'"_.___ i , t f i 1 � _ ~' ! y t \ \ �\ ♦ __ `___ - "'.' —SOD �. --_ \ � — - 1 _ � I / 1 ,,. LOT — 7350 I I i j i i i 4r 11 i t i i ao, 1 i i % li hp 46 LOT 54T 41 4T LOT 01 I z.1 .i I LOT I I s i a s OT AS I + 5) a1 LOT sor 195�`1\4 I OI A s'" LOT' 1 .Lor aD LOT aT t LOT / 1 � i/ LOT • LW L4 24 ®11 i®mmm 21 :r --- f SF �T --- j TO B j A4 Aa 1 7830S17- I LOT LOT L z .�T LOT LOT L 85 IT LOT 1j � ai t . zz TO 135 ' NSF ITO�E �4 LpT 43 Jar 41 41 �W39 4pi ..LO 47 1 I SV-- 86 I I 1 10590 SF 1 — 14.1it0 S� LOt O LOT vT � 1 f IMIE --TO-B3a 17430 S i> F to, I +e ,or 5A a f sS VI to, 1 LOT 11 , LOT TO DITCH 2C ..--t 5005 SF IV ' 10 DITCH 26 �15�/30r,Sf F r r ' y D LOT Y / T C 2ASF - u 14860 SF I Scale: 1 :• 7 PROFFIT RD TH NORTH POSTDEV INLET DRAINAGE MAP PROF FIT RD TH TO CULVER : NORTH POSTDEV 15.7 AC TO L 2.6ACIMP' CULVERT DRAINAGE 5.0 AC WOODS i.1 ACT RF MAP i i i �� i iC:3 CAI� \4 r r i r 1 � CD 100, + x r S } �y ✓ ; O `? 4 g 1 x, r jr ED dT maw 400 maw .w ♦ 0 ` ' v Scale: 1 `1 00' 45 Proffit Rd TH North Inlet Drainage Area Summary Impervious C 0.9 Pervious C 0.3 To Inlet Area Impervious Turf C A A7 10,590 7,201 3,389 0.71 0.24 A6 4,125 2,805 1,320 0.71 0.09 A5 19,540 13,287 6,253 0.71 0.45 A4A 15,260 10,377 4,883 0.71 0.35 A4 9,540 6,487 3,053 0.71 0.22 A3 3,755 2,553 1,202 0.71 0.09 A2 7,350 4,998 2,352 0.71 0.17 B7 14,180 9,642 4,538 0.71 0.33 B6 6,815 4,634 2,181 0.71 0.16 BSA 19,825 13,481 6,344 0.71 0.46 B5 13,255 9,013 4,242 0.71 0.30 B4 7,830 5,324 2,506 0.71 0.18 133A 17,430 11,852 5,578 0.71 0.40 B3 9,880 6,718 3,162 0.71 0.23 D 7,775 5,287 2,488 0.71 0.18 C2 9,295 6,321 2,974 0.71 0.21 F2 684,100 113,256 570844 0.40 15.70 G 14,860 9,160 5,700 0.67 0.34 DITCH 2,A 6,880 860 - 6,020 0.38 0.16 DITCH 2B 15,230 0 15,230 0.30 0.35 DITCH 2t 1 5,005A 0 1 5,005 0.30 1 0.11 46 pealdg lwodplW N r m '`{i v N N m g v o w o R ui v pi C\i HIQ N 1 O h b 0 O NO N MO Ci r N N. 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U L o _ QI -= J r c C U O o o O � c IA SO V?. c a u S U U ev m ej. a ¢ O C a a U E 7 X z O a a E a ¢ � c N 7 a a a E `o t aL a U p M c CS ?t7 Cil Q U L) U t co c�[ N P4:U O N O w U m 0 :E 0 a O N E E E rn C N ° E o` a c O 7 N L Q N O la8j 'iDZLs deidiLo OSp Ak M C) —j LL- LAJ CL te CA: I.— LA- a It x LLJ fm C] Or a- f.- LLJ LAJ —i M d,% L16 C> Li L=. 7 + Lr3 C, C� v to CD LO Chapter 8 - Culverts Appendix 8C-2 Inlet Control, Circular Corrugated Metal CHART 2 0 190 10,000 186 T 8,000 EXAMPLE {I} 156 6,000 D•36 incRssl3.0 fast) 6• ('L) 3,000 o•sscft 144 4,000 Nw y, 6. {) 132 � Nw 3.000 0 {coop 120 s lt1 l.a s.a S, 6. ki 2,000 109 n (3) t.i 6.6 4• a n0 in test 3. 4. — 96 1,000 3. Z) 800 3. 64 w 600 500 P' 72 400 /�• --� — --► 2' W 300 2. U ? ; con Go t 200 p4 2 z f�►% a t.S I.S 54 w t w 100 / j 49 ¢ 80`� o _ 60 ' z 0 CULVERT FRFS 42 o 50 X ' ° 1.0 Q=26.17 46 a 1.0 �'' ENTRANCE ¢ 30 HW SCALE ._ wW 33 TYPE q 8 a 20 �j {11 Npaaen : 30 (21 fella1e0 to Valletta Q v to slope i 9 m 27 10 01 Pro+aetint — — 0 8 7 7 = 24 cm 6 21 5 To use scale (2) 0t (3) 0+o)eet 4 aarisontoll, to Scala (11. ttua — --- 6 rso ttntoat tacllna'll tint through 16 3 D OnQ Q scopepi, of favor$• at IB illuuraud. 6 2 15 O S 5 L i2 HEADWATER DEPTH FOR C. M. PIPE CULVERTS 8UPE0%U Of PU90C ROAD! AAN, 19Bp WITH INLET CONTROL Source: HDS-5 1 of 1 VDOT Drainage Manual 51 Proffit Rd TH North Time of Concentration Calculations PREDEV TOC: POA 1 ONSITE 100 ft overland flow 12.2% slope 133 ft s. c. flow -woods 17.5% slope 400 ft Channel POSTDEV TOC: ONSITE BYPASS 100 ft overland flow 14.2% slope 97 ft S. c. flow -woods 19.3% slope 446 ft Channel 0.35 C-value 8.9 min Seelye Chart 2.0 fps velocity 1.1 min. NEH Figure 15-4 20.4 ft height 2.4 min. Kirpich Chart TOC= 12.4 min. 0.35 C-value 8.6 min Seelye Chart 2.2 fps velocity 0.7 min. NEH Figure 15-4 12.3 ft height 3.1 min. Kirpich Chart TOC= 12.4 min. 52 PROFFIT RD TH NORTH TOC NOMOGRAPHS 35 Figure 15-4 Velocity versus slope for shallow concentrated flow MOME� 30 10n Paved ,y 0.9 0.b z M 25 07 300 � 0.n Bare o 0.4+ 200 Soil s 20 w i Poor � Grass w L~� .5 � z surface < L- er. AvGlass ,r r3 J 0.5 w z 0.21 z L0 0 5 w a 901-1 gp Dense v, 20 w / 70 Grass .a \ z/ 0 01( 60 O � w r 0.04 O.Of 20 w — 40 i 0.05 10 0 0.01 30 r w uj 6.03 J Ts 20 g 0.02 7 0 g 0.01 OVERLAND FLOW TIME (Seelye Char[) Source: Data Book for Civil Engine�rc. E.E. Seelye Plate 5-1 V-11 TRAVEL TIME FOR CHANNEL FLOW (Kirplch Chart) x (rNNct A I Source: VDOT TIME OF CONCENTRATION OF SMALL DRAINAGE BASINS V 13 Plate 5-3 0.006 Co Velocity (f 1s) LEGEND: RED: PREDEV ONSITE TOC BLUE: POSTDEV BYPASS TOC 53 ESCP Calculations: Sediment Basin Design Spreadsheet Sediment Basin Design Nomographs 54 6 I PROFFIT RD TH NORTH Orange cells need input, white cells are calculations. Basin I SB-1 Step 1: Preliminary Design Top of Dam ')u_ u Downstream Toe of Dam 592.0 Barrel length (ft) 127.0 Slope of principal spillway barrel (%) I � fim, Step 2: Calculate Runoff Rational Method Drainage Area (ac) 450 C 0.8 12 4.3 125 6.6 Q2 (cfs) 14.5 Q25 (cfs) 22.3 Step 3: Principal Spillway From Plate 3.14-8 Spillway Capacity with emergency spillway (cfs) 22.3 Riser Diameter (in) 49 Actual head (ft) 1.00 QP (max) 24.0 Step 4: Emergency Spillway From Table 3.14-C Required spillway capacity 0.0 HP 0.0 b - Bottom width (ft) 0 S - slope of exit channel (ft/foot) 0.00 X - minimum length of exit channel (f 0 Step 5: Grade Basin Design Parameters Maximum Top of wet Storage 499.0 Required Wet + Dry Storage (cf) 16,281 Wet Storage Required Volume (cy) 302 Required Volume (cf) 8,141 Minimum Standpipe Invert 404.0 Cleanout Required Volume (cy) 149 4 55 a I Basin SB-1 Cleanout Required Volume (cf) 4,010 Design Elevation Area Bottom of Wet Storage 41 495.0 Cleanout Elevation 496.0 497.0 2,5 Top of Wet Storage 197.E 1 3.0( Cleanout Volume (cf) 4,036 Wet Storage Volume (cf) 8,392 Wet Storage Volume (cy) 311 Dry Storage Required Volume (cy) Required Volume (cf) Maximum Top of Dry Storage Bottom of Dry Top of Dry Dry Storage Volume (cf) Dry Storage Volume (cy) 302 8,141 500.0 Design Elevation Area (s Storagel 497.6 3,064 499.0 3,790 Storage 500.0 4,375 Step 6: Final Details Upstream Toe of Dam Principle Spillway Elevation Trash rack and anti -vortex device From Table 3.14-D: Diameter (in) Height (in) From Retention Basin Design and Plate 3.14-B: Head on barrel (ft) Q, (max) Barrel diameter (in) Dewatering Orifice Design Riser Height h (ft) S (cf) Q (cfs) A (sf) d (ft) Dewatering Orifice Diameter (in) Flexible Tubing Diameter (in) 8,880 329 494.0 499.0 7.0 39.0 18 6.0 1.2 8,880 0.41 0.078 0.315 6 8 56 • 1992 1000 °°° Riser Inflow Curves 600 ,. Legend 5001— 3/2 i } Weir flow, Qw 9.739 DrH 400—"" -- Orifice flow, Qo=3.782 DrH 300 1 200 — ' mr Ell! MORI` 1 FR f 4", " S '00111110'Amm Noun Me MOVIE irar.�/'+ ra.r�rr:wa...1eI1• ``• •�• w•aw_���������ou /IlrII•�M•'//Y,�'t'/ 'Je•t�e`•�!•�f1•e1•ef �•e1l���1••1/•U rri x,,►',t1,�.rw.',0r,I�«wy�p eeree�e�e��e�w�uuuu wrLl/PJFANNNIM � ArrnmrAel"tA"a"Up" 'IAVIA7,"U iiwlqq MMMM on W�MVAW ni rioFishft,►�MQ, /1ill� ■w i��lr�swNa�fwyuv�ewBMa��rlE�i•NESERfi•I•ooIilNuilInilNu Y!/J/%zj0m11 MAMMA nilunl�l� HM Am too, nwasured from crest of riser �i��i11111111 Source: USDA-SCS III-97 3.14 Plate 3.14-8 Independent Reports: Excerpt from NRCS Soils Report NOAA Precipitation Report 58 Q co Cy) Co O 2 O c co i _m n > > i+ N N 3 N Na d >E U) � �- 3 G> c p D 0rrJ�W i 0� 0 0 0' m Cl) O rm M N CA C4 d Q E M W Q O d C -a 0 c Z 2 i+ CO U J O J LU Q � "� N m N U) c cz } as6 06 0 r n N Z N W s D n° Q 5, U) — W i6 S2 U d LL H N Z C U 0 J d o co V p j W z -0 IL CO m 00 LL Z d a i .Q i�► LL IL W O O O O CO O LO O r 0) toto r ri CO t0 v N M Ca m 00co N n Di r CO T Co O T O i C COO i! '.. N: r- i LO CO V r m LC! 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N 00 N V C7 O M N 4 N .... <O O r-4 00CC co,cl) CA v _LO 00 co, LnN O 0, r LnONcoNO Ni co v M (7M cq O 06 -... j pi c r CO N NCD M M O In r,m00M (O_n 0COL e) 41 C ' N, N' r, W N Qi Q O ILn O CD o N r .: N r w 7 O C� r- O C j LO O Cj � N C.j LO IT L6 I Cl) Cp tt -e M 1� CO 0 a) Cp M, O 0) O O C27 t Q) N co r, N N U) N� m M o. O 0) cp 00 O O LO v, O N . N co �.. cli m o 0 CO CO W �,. T LO O V I- C09 N r NO CCY) QLA oo O' O' V tr r CO N, N 00 CM N 0)M O n LO M O r-O O ti O O O O) � n N r M- o M N rn: D) N 0, N M o �� r) r CO O 00 4 n 00 N CD CO Cl) N O 00 It It t N 0,W LO V N O IT 4 N Lp6o N f n, LO N O O '<O O CD O 0 N � OM D Q N00 LC UN �M _�. NM M0 CO N .. O M (O n CO O c) CND I� N CC) Cl) vcq 8, q cq 7 n 7 rn . - c" Ln cc CrL�C`V, O O N 0 00 .F-7 M M 00 M(O O O OCl) ' N, M,L M. 0 dL2r- rL L L LLLL t FC4 m Lq LO N CM W N M a) LO I cc •wy` W ca y t0 2 r_ n IA R E U) E :Q r� <f 71 ^L^ L Q'i <C U` N, - ■ rn L Ca _ - E" S E ti 0 I' C 4 M „6£SZ o8L M.T,9Z o8L r z z too Vmm f+1 l�1 z - z co M o� M,b£SZ AL d m. j§ zQ ZU M J 9Z AL q & MAP LEGEND Area of Interest (AOI) 0 Area of Interest (AOI) Soils Soil Rating Polygons A A/D B B/D C C/D 0 D 0 Not rated or not available Soil Rating Lines ,y A �r A/D B B/D ry C C/D .v D Not rated or not available Soil Rating Points ® A ■ A/D ■ B ■ B/D Hydrologic Soil Group —Albemarle County, Virginia ■ C ■ C/D ® D 0 Not rated or not available Water Features Streams and Canals Transportation +-t-F Rails Interstate Highways US Routes Major Roads Local Roads Background . Aerial Photography MAP INFORMATION The soil surveys that comprise your AOI were mapped at 1:15,800. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the 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. USDA Natural Resources Web Soil Survey 10/3/2069 21111111111111 Conservation Service National Cooperative Soil Survey Page 2 of 4 Hydrologic Soil Group —Albemarle County, Virginia r Hydrologic Soil Group Map unit symbol Map unit name Rating Acres In AOI Percent of AOI 27B Elioak loam, 2 to 7 B 4.1 27.8% percent slopes 27C Elioak loam, 7 to 15 B 2.9 20.0% percent slopes 27D Elioak loam, 15 to 25 B 7.4 50.8% percent slopes 88 Udorthents, loamy, 2 to 0.2 1.4% 25 percent slopes Totals for Area of Interest 14.6 100.0% Description Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long -duration storms. The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B/D, and C/D). The groups are defined as follows: Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink -swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes. LLSDk Natural Resources Web Soil Survey 10/3/2019 Conservation Service National Cooperative Soil Survey Page 3 of 4 63