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HomeMy WebLinkAboutWPO202200017 Stormwater Management Maintenance Agree. 2022-04-12SHIMP ENGINEERING, P.C. Design Focused Engineering Stormwater Management Plan Calculation Packet Tax Map 45, Parcel 100 Tax Map 45, Parcel 100A Tax Map 45, Parcel 101 Tax Map 45, Parcel 101B Project Name: 664 West Rio Prepared by: Shimp Engineering P.C. Date: April 12, 2022 23 v �SHIMP is 11��0o. 5181 k—PDXAL V, 912 E. High Sr. Charlottesville, VA 22902 1434.227.5140 1 shimp-engineering.com SHIMP ENGINEERING, P.C. Design Focused Engineering April 12, 2022 Albemarle County Department of Community Development 401 McIntire Road Charlottesville, VA 22902 Regarding: WPO 2022000XX 664 West Rio — VSMP Plan SWM Calculation Packet Dear Reviewer, Enclosed is the stormwater calculation packet for 999 Rio Road VSMP Plan. The development property has an area of 3.32 acres and a disturbed area of 3.13 acres. The project is a private redevelopment of a site to create residential apartment building, a self -storage building and a linear park. The site is naturally divided by a stream located to the north of the property, and the site outfall is located to the northeast of the property. To analyze the water quantity, the site is divided into two drainage areas based on the stream on site. The drainage area to the south of the stream (Drainage Area 1) is routed to detention systems to meet water quantity requirements in 9VAC25-870-66-B(3) and 9VAC25-870-66-C. While the drainage area to the North of the Stream (Drainage Area 2) is considered to have a sheet flow conditions to meet the requirements in 9VAC25-870- 66-D. The site also meets the water quantity requirements set forth in 9VAC25-870-65. Runoff Quality Narrative: To address runoff quality requirements set forth in 9VAC25-870-65, the site land cover information was entered into the VRRM Re -development Spreadsheet. This included pre -development and post -development land areas. The VRRM spreadsheet, attached in this packet, showed that the project required a total phosphorous (TP) reduction of 3.75 lb/yr. A purchase of 3.75 lbs/yr phosphorous credit shall be made to achieve required TP reduction for this site. Treatment Required (Total Phosphorous) Treatment Provided (Total Phosphorous) 3.75 lbs/yr 3.75 lbs/yr Runoff Quantity Narrative: SWM Quantity is satisfied by analyzing concentrated runoff from the development at site outfall at the northeast corner of the development property. The site drainage area is divided into two drainage areas based on a stream north of the property, drainage area to the south of the stream (drainage area 1) and drainage area to the north of the stream (drainage area 2). Both drainage area 1 & 2 flow to the site outfall but the analysis for them differs as follow: SHIMP ENGINEERING, P.C. Design Focused Engineering DYai/lageArea 1: 9VAC25-870-66-B(3) requires that concentrated runoff from development at the site outfall meet the energy balance equation. To achieve this, all concentrated runoff from the this drainage area will be routed to two underground detention facilities and then to site outfall. Drainage area 1 is divided into three segments, drainage area A, B & C. 1. Drainage area A has 0.837 acres of potential stormwater runoff through a combination of impervious and turf areas which is managed by routing it to an 84-inch CUP underground detention system 1, and then to a 96-inch CMP underground detention system 2 and then to site outfall. 2.Drainage Area B has 1.610 acres of potential stormwater runoff, also flowing through a combination of impervious and turf areas, which is managed by routing it to a 96-inch CMP underground detention system 2 and then to site outfall. 3.Drainage area C has 0.370 acres of turf that the runoff is left unmanaged and bypasses both detention systems and flows directly to the site outfall. The runoff from the detention systems meets the energy balance equation requirements set forth in 9VAC25-870-66-B(3). 9VAC25-870-66-C(2).b requires that the concentrated stormwater flow to stormwater conveyance systems that currently experience localized flooding during the 10-year 24-hour storm event and Releases a post -development peak flow rate for the 10-year 24-hour storm event that is less than the predevelopment peak flow rate from the 10-year 24-hour storm event. This condition has also been satisfied as the peak flow for the 10-year 24-hour stone event for the post development is less than the pre -development flow for the 10-year 24-hour stone event. Pre-dev Peak Runoff Max. Allowed Peak Runoff Post-dev Peak Runoff 1-Yr 1.17 cfs 0.21 cfs 0.21 cfs 10-Yr 6.53 cfs 6.53 cfs 2.56 cfs Drainage Area 2: Drainage area 2 lies north of the stream and has 0.397 acres of potential runoff in a stormwater runoff through a combination of impervious and turf areas which flow to the stream and then reaches the site outfall. This area is designed to have sheet flow runoff and meets the requirements in 9VAC25-870-66- D. 9VAC25-870-66-D requires evaluating for potential impacts on down -gradient resources for increased volumes of sheet flow that will cause or contribute to erosion, sedimentation, or flooding. The pre development drainage area 1 has 1.17 cfs Q, and 6.69 cfs Q,o while pre development drainage area 2 has 0.21 cfs Q, and 1.23 cfs Qio. Since drainage area 1 and drainage are 2 both flow to the same site outfall that is being analyzed, adding the two pre development flows together results in the following: Q Pre deg for 1-year = 1.17 cfs + 0.21 cfs = 1.38 cfs Q p d, for 10-year = 6.69 cfs + 1.23 cfs = 7.92 cfs The post development drainage area 1 has 0.21 cfs Q, and 2.60 cfs Q,o while pre development drainage area 2 has 0.47 cfs Q, and 1.73 cfs Q,o. Since drainage area 1 and drainage are 2 both flow to the same SHIMP ENGINEERING, P.C. Design Focused Engineering site outfall that is being analyzed, adding the two post development flows together results in the following: Q p�t-0ev for 1-year = 0.21 cfs + 0.47 cfs = 0.68 cfs Q �-a, for 10-year = 2.56 cfs + 1.73 cfs = 4.29 cfs When comparing the pre and post development flows, the results show that the post development flow is reduced by 5 1 % for the 1-year storm and by 45% for the 10-year storm. Since the runoff to the site outfall for the post -development has been decreased significantly from the runoff for the pre -development, there will be no runoff that contributes to erosion, sedimentation, or flooding of down gradient resources which therefore meets the requirements in 9VAC25-870-66-D. If you have any questions about this calculation packet please do not hesitate to contact me at: steohanie@shimp-en ing eering com or justin@shimp-en ing eering com or by phone at 434-299-9843. Regards, Stephanie Paul Shimp Engineering, PC SHIMP ENGINEERING, P.C. Design Focused Engineering Contents: Water Quantity Calculations: Pre -Development Drainage Area Map Pre -Development TOC Calculations Pre -Development TOC Nomographs Pre -Development HydroCAD Report Post -Development Drainage Area Maps Post -Development TOC Calculations Post -Development HydroCAD Report Energy Balance Equations Post -Development Inlets Drainage Area Maps Inlet Drainage Area Summary VDOT LD-204 Pipe Drainage Area Summary VDOT LD-229 Water Quality Calculations: Pre -Development VRRM Land -use Map Post -Development VRRM Land -use Map VRRM Redevelopment Spreadsheet - 1 VRRM Redevelopment Spreadsheet - 2 VRRM Redevelopment Spreadsheet - 3 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 TOC Calculations Pre -Development TOC Nomographs Pre -Development HydroCAD Report Post -Development Drainage Area Map Post -Development TOC Calculations Post -Development HydroCAD Report Energy Balance Equations Post -Development Inlets Drainage Area Map Inlet Drainage Area Summary VDOT LD-204 Pipe Drainage Area Summary VDOT LD-229 S1 ua ru a�a r vu rua�a ua r v' a r yr ENGLYMNG-LANOPLUNNYG-PRQIETKANAOM NT 664 West Rio Pre Development Drainage Area Map NJ Scale: 1 V V V VELOPMENT \GE AREA 2 38 AC TM. 45-948 120 180 664 West Rio Time of Concentration Calculations Pre Dev DA 1 to Siteoutfa111 TOC (Onsite) 100 ft Overland Flow 1 1.58%1 slope 1 0.35IC-value I 11.0 min ISeelyeChart 328.0 ft S.C. Flow 1 8.95%1 slope 1 2.0 fps Ivelocity I 2.7 min. INEH Figure 15-4 180.0 ft Channel I 1 1 20.0 ft 11height I 1.0 min. IKirpich Chart TOC= I 14.7 min. SOO Sao Paved 0.9 400 0.8 1 300 0.7 0.8 R safe 200 Soil 90 Demo 80 Olasa 70 60 50 40 t2 30 0 z 20 U 10 me- T c= 0.225 L042 S-0.19 C -10 TF = O e,laM Flow Tama, mnMaa i =I"th of Shy Not 35 S - SNIP, leavr..t C = Rallonal ^ vaim Na, Gmu•,d CharacN: 30 25 H 20 - 0.5 Z s D. = 2 J w S 0.5 0.3a0 w 15� ~ O 2.0 5.0 w - 0.2 \ cwi \ ice' R U 20 w � 10 J ? u 9 z 0 a Po+tono" "C" Value Nv Sala". Drauoo cro". ar Oenx Oraaa 0.215 Fses+ 0�26 _ 7 sver0ga Grass SYr Face O.Bc t own O. lO Ppar Ortua $YHOCC Pee+ura 0.00 0.40 B Para soli 0.43 PoveO 0.90 OVERLAND FLOW TIME REPRINTED WITH PERMISSION FROM "DATA BOOM FOR CIVIL ENGINEERS" VOL. I - DESIGN 2ild En ITION 11951) BY E. E. SEELVE SI NVENGINEERING, P.C. ENGGYEEUN6-L4NDFMAMN6 -FRaffL7MANA6EAFM .Lo "I'"LL... aaaea er .� Ma_(4<4) 227-5140 1.00 0.90 0.80 0.70 0.60 0.50 0.40 0.30 0.20 0.10 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0.005� 0 w w .o ot-wwo tv ea w to�awo a o O OO O O 0000f+ N velocity (fus) 664 West Rio Pre Development Drainage Area Time of Concentration TRAVEL TIME FOR CHANNEL FLOW (Kirpich Chart) H (feet) 500 Tc (min.) 200 100 100 L (feet) ]0000 FLa�Ie 50 F50 5000 u Note: e o a 0) For uae with flat...) channels; 0 10 For paved channels, nu It i ply by 0.2 1000 � 10 � F ~ s 0 S 500 5 100 t t TIME OF CONCENTRATION OF SMALL DRAINAGE BASINS Source: VDOT V-13 Plate 5-3 I I 3S 1S ZDrajDevelopment nge Area 2 Pre Development 4L Drainage Area 1 2L Site Outfall Site Outfall Subcat Reach Aon Link Pre Dev Pre Dev Type II24-hr I yr, 24 hr Rainfall=3.01 " Prepared by Shimp Engineering, P.C. Printed 4/1/2022 HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Paee 2 Time span=0.00-72.00 hrs, dt=0.01 hrs, 7201 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 Development Drainage Area 1 Runoff Area=2.870 ac 4.84% Impervious Runoff Depth=0.44" Tc=14.7 min CN=63 Runoff=1.17 cfs 0.105 of Link 2L: Site Outfall hrtlow=1.17 cfs 0.105 of Primary=1.17 cfs 0.105 of Subcatchment 3S: Pre Development Drainge Area 2 Runoff Area=0.398 ac 0.00% Impervious Runoff Depth=0.37 Tc=5.0 min CN=61 Runoff=0.21 cfs 0.012 of Link 4L: Site Outfall hrtlow=0.21 cfs 0.012 of Primary=0.21 cfs 0.012 of Pre Dev Pre Dev Type II 24-hr I yr, 24 hr Rainfall=3.01 " Prepared by Shimp Engineering, P.C. Printed 4/l/2022 HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Paee 3 Summary for Subcatchment 1S: Pre Development Drainage Area 1 Runoff = 1.17 cfs @ 12.10 hrs, Volume= 0.105 af, Depth= 0.44" Runoff by SCS TR-20 method, UH=SCS, Time Span-- 0.00-72.00 hrs, dt= 0.01 hrs Type H 24-hr 1 yr, 24 hr Rainfall=3.01" 0.139 98 Paved parking, HSG B 2.731 61 >75% Grass cover, Good, HSG B 2.870 63 Weighted Average 2.731 95.16% Pervious Area 0.139 4.84% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 14.7 Direct Entry, Time of Concentration Summary for Link 2L: Site Outfall Inflow Area = 2.870 ac, 4.84% Impervious, Inflow Depth = 0.44" for 1 yr, 24 hr event Inflow = 1.17 cfs @ 12.10 hrs, Volume= 0.105 of Primary = 1.17 cfs @ 12.10 hrs, Volume= 0.105 af, Atten= 0%, lag= 0.0 min Primary outflow = Inflow, Time Span-- 0.00-72.00 hrs, dt= 0.01 hrs Summary for Subcatchment 3S: Pre Development Drainge Area 2 Runoff = 0.21 cfs @ 11.99 hrs, Volume= 0.012 af, Depth= 0.37" Runoff by SCS TR-20 method, UH=SCS, Time Span-- 0.00-72.00 hrs, dt= 0.01 hrs Type H 24-hr 1 yr, 24 hr Rainfall=3.01" Area (ac) CN Description 0.398 61 >75%" Grass cover, Good, HSG B 0.398 100.00%" Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Time of Concentration Summary for Link 4L: Site Outfall Inflow Area = 0.398 ac, 0.00% Impervious, Inflow Depth = 0.37" for 1 yr, 24 hr event Inflow = 0.21 cfs @ 11.99 hrs, Volume= 0.012 of Primary = 0.21 cfs @ 11.99 hrs, Volume= 0.012 af, Atten= 0%, lag= 0.0 min Primary outflow = Inflow, Time Span-- 0.00-72.00 hrs, dt= 0.01 hrs Pre Dev Pre Dev Type II 24-hr 10 yr, 24 hr Rainfall=5.51 " Prepared by Shimp Engineering, P.C. Printed 4/1/2022 HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Paee 4 Time span=0.00-72.00 hrs, dt=0.01 hrs, 7201 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 Development Drainage Area 1 Runoff Area=2.870 ac 4.84% Impervious Runoff Depth=1.84" Tc=14.7 min CN=63 Runoff-6.69 cfs 0.440 of Link 2L: Site Outfall hrtlow=6.69 cfs 0.440 of Primary=6.69 cfs 0.440 of Subcatchment 3S: Pre Development Drainge Area 2 Runoff Area=0.398 ac 0.00% Impervious Runoff Depth=1.69" Tc=5.0 min CN=61 Runoff=1.23 cfs 0.056 of Link 4L: Site Outfall In low=1.23 cfs 0.056 of Primary=1.23 cfs 0.056 of Pre Dev Pre Dev Type II 24-hr 10 yr, 24 hr Rainfall=5.51 " Prepared by Shimp Engineering, P.C. Printed 4/l/2022 HydroCAD® 9.10 s/n 07054 0 2011 HydroCAD Software Solutions LLC Paee 5 Summary for Subcatchment 1S: Pre Development Drainage Area 1 Runoff = 6.69 cfs @ 12.07 hrs, Volume= 0.440 af, Depth= 1.84" Runoff by SCS TR-20 method, UH=SCS, Time Span-- 0.00-72.00 hrs, dt= 0.01 hrs Type H 24-hr 10 yr, 24 hr Rainfall=5.51" 0.139 98 Paved parking, HSG B 2.731 61 >75% Grass cover, Good, HSG B 2.870 63 Weighted Average 2.731 95.16% Pervious Area 0.139 4.84% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 14.7 Direct Entry, Time of Concentration Summary for Link 2L: Site Outfall Inflow Area = 2.870 ac, 4.84% Impervious, Inflow Depth = 1.84" for 10 yr, 24 hr event Inflow = 6.69 cfs @ 12.07 hrs, Volume= 0.440 of Primary = 6.69 cfs @ 12.07 hrs, Volume= 0.440 af, Atten= 0%, lag= 0.0 min Primary outflow =Inflow, Time Span-- 0.00-72.00 hrs, dt= 0.01 hrs Summary for Subcatchment 3S: Pre Development Drainge Area 2 Runoff = 1.23 cfs @ 11.97 hrs, Volume= 0.056 af, Depth= 1.69" Runoff by SCS TR-20 method, UH=SCS, Time Span-- 0.00-72.00 hrs, dt= 0.01 hrs Type H 24-hr 10 yr, 24 hr Rainfall=5.51" Area (ac) CN Description 0.398 61 >75% Grass cover, Good, HSG B 0.398 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Time of Concentration Summary for Link 4L: Site Outfall Inflow Area = 0.398 ac, 0.00% Impervious, Inflow Depth = 1.69" for 10 yr, 24 hr event Inflow = 1.23 cfs @ 11.97 hrs, Volume= 0.056 of Primary = 1.23 cfs @ 11.97 hrs, Volume= 0.056 af, Atten= 0%, lag= 0.0 min Primary outflow = Inflow, Time Span-- 0.00-72.00 hrs, dt= 0.01 hrs Pre Dev Pre Dev Type II24-hr 100 yr, 24 hr Rainfall=9.04" Prepared by Shimp Engineering, P.C. Printed 4/1/2022 HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Pace 6 Time span=0.00-72.00 hrs, dt=0.01 hrs, 7201 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 Development Drainage Area 1 Runoff Area=2.870 ac 4.84% Impervious Runoff Depth=4.50" TF14.7 min CN=63 Runoff=16.94 cfs 1.077 of Link 2L: Site Outfall Inflow=16.94 cfs 1.077 of Primary=16.94 cfs 1.077 of Subcatchment 3S: Pre Development Drainge Area 2 Runoff Area=0.398 ac 0.00% Impervious Runoff Depth=4.26 Tc=5.0 min CN=61 Runoff=3.15 cfs 0.141 of Link 4L: Site Outfall Inflow=3.15 cfs 0.141 of Primary=3.15 cfs 0.141 of Pre Dev Pre Dev Type II 24-hr 100 yr, 24 hr Rainfall=9.04" Prepared by Shimp Engineering, P.C. Printed 4/1/2022 HydroCAD® 9.10 s/n 07054 0 2011 HydroCAD Software Solutions LLC Pace 7 Summary for Subcatchment 1S: Pre Development Drainage Area 1 Runoff = 16.94 cfs @ 12.07 hrs, Volume= 1.077 af, Depth= 4.50" Runoff by SCS TR-20 method, UH=SCS, Time Span-- 0.00-72.00 hrs, dt= 0.01 hrs Type H 24-hr 100 yr, 24 hr Rainfall=9.04" 0.139 98 Paved parking, HSG B 2.731 61 >75% Grass cover, Good, HSG B 2.870 63 Weighted Average 2.731 95.16% Pervious Area 0.139 4.84% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 14.7 Direct Entry, Time of Concentration Summary for Link 2L: Site Outfall Inflow Area = 2.870 ac, 4.84% Impervious, Inflow Depth = 4.50" for 100 yr, 24 hr event Inflow = 16.94 cfs @ 12.07 hrs, Volume= 1.077 of Primary = 16.94 cfs @ 12.07 hrs, Volume= 1.077 af, Atten= 0%, lag= 0.0 min Primary outflow =Inflow, Time Span-- 0.00-72.00 hrs, dt= 0.01 hrs Summary for Subcatchment 3S: Pre Development Drainge Area 2 Runoff = 3.15 cfs @ 11.96 hrs, Volume= 0.141 af, Depth= 4.26" Runoff by SCS TR-20 method, UH=SCS, Time Span-- 0.00-72.00 hrs, dt= 0.01 hrs Type H 24-hr 100 yr, 24 hr Rainfall=9.04" Area (ac) CN Description 0.398 61 >75% Grass cover, Good, HSG B 0.398 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Time of Concentration Summary for Link 4L: Site Outfall Inflow Area = 0.398 ac, 0.00% Impervious, Inflow Depth = 4.26" for 100 yr, 24 hr event Inflow = 3.15 cfs @ 11.96 hrs, Volume= 0.141 of Primary = 3.15 cfs @ 11.96 hrs, Volume= 0.141 af, Atten= 0%, lag= 0.0 min Primary outflow = Inflow, Time Span-- 0.00-72.00 hrs, dt= 0.01 hrs ® POST DEV DETENTION SYSTEM 1 DA TO SITE OUTFALL IMP. POST DEV DETENTION SYSTEM 1 DA TO SITE OUTFALL TURF. POST DEV DETENTION SYSTEM 2 DA TO SITE OUTFALL IMP. POST DEV DETENTION SYSTEM 2 DA TO SITE OUTFALL TURF. ° tt POST DEV BYPASS DA TO SITE OUTFALL TURF. ® POST DEV DA 2 TO SITE OUTFALL IMP. © POST DEV DA 2 TO SITE OUTFALL TURF. --- SOILS - — - POST DEVELOPMENT DETENTION SYSTEM 1 DRAINAGE AREA A (MANAGED) - — - POST DEVELOPMENT DETENTION SYSTEM 2 DRAINAGE AREA B (MANAGED) POST DEVELOPMENT DETENTION SYSTEMS BYPASS DRAINAGE AREA C (UNMANAGED) - — - POST DEVELOPMENT DRAINAGE AREA 2 (SHEET FLOW) Post-Dev Detention System I Drainage Area 1 (Managed) CN 98 61 SF AC Building & Pavement 30,200 0.693 82.8 Impervious 30,200 0.693 82.8 Turf 6,271 0.144 ]7.2 Total Drainage Area 36,471 0.837 100.0 Weighted CN TOC= 92 5.0 Post-Dev Detention S stem 2 Drainage Area 1(Ma nage d CN 98 61 SF AC % Building & Pavement 61442 1.411 87.6 Impervious 61,442 1.411 87.6 Turf 8,676 0.199 12.4 Total Drainage Area 70,118 1.610 100.0 1 Weighted CN TOC= 93 5.0 Post-Dev Detention Systems pass Drainage Area i (Unmanaged) CN 61 S171 AC % Turf 16,1311 0.3701 100.0 Total Drainage Area 16,131 0.370 100.0 We' kited CN TOC=5.0 61 Post-Dev Drainage Area 2 (Sheet Flow) CN 98 61 SF AC Building & Pavement 3663 0.084 5.21 Impervious 3663 0.084 5.2 Turf 13,633 0.313 19.4 Total Drainage Area 17,296 0.397 100.0 weight CN TOC= 69 5.0 "MMENNNEFRIN6. PC FN6A ERNNG-L4NDPLANNN 6-PRQIECTKANAGEMF.NT .-.•yam.-LL.. - 2.... . arN.s M•° � 1�fl1N .wM NOTE: ALL SOILS IN =Y DRAINAGE AREA 1 ARE — HSG B ��—�— W. 45-100C ti �1 fl 1. F-� t i I _ 1 POST DEVELOPMENT t i DETENTION SYSTEMS 1�1 BYPASS DRAINAGE -- AREA (UNMANAGED) A=0.370 AC c 1 W. 45-100B 1 . DASHED 11NE 1 1 I REPflESENPNC ME ZMINe DINSIC° I I I 1 R1029 ABC REX RG R1029 MC - COfQ MEA (AVVROX.)kill O ♦.I,J♦ uJO0oJ0�� rJJ�J. tl.JJJ♦ ♦JJJJJ JJJJ �JJJ .JJJt�JJJJJJ� JrJJ.J.�.J.J� JJJ�JJJVJJ.J.J�J. ��JS �J�i►JJF-1J. ,J•.O•J•J i►JJ�►J.JJ� o • �O♦ ♦Ju c►SA - � � - AJJJJ4 nay _-f 1 �-- TM. 45-105 6� 664 West Rio Pre Development Drainage Area Map Sale: 1"=60' RI i POST DEVELOPMENT DRAINAGE AREA 2 (SHEET FLOW) A=0.397 AC W. 45-173 -_ f- �f i SITE , i/ OLITFALL ri 60 120 180 664 West Rio Time of Concentration Calculations All Post Development ToCs assumed to be 5 minutes. This assumption dictates very conservative design factors. TC 1 5.0 1 MINUTES 13 3S Detention System 2 DA Detention System t DA B (Managed) A(Managed) 2P -D 4P Detention System t Detention System 2 Detentes System 6L Bypass DA C (Unmanaged) Site Outfall Subcat Reach Aon Link Drainage Area 2 8L Site Oudall Post Dev Post Dev Type II24-hr 1-Year Rainfall=3.01 " Prepared by Shimp Engineering, P.C. Printed 4/l/2022 HydroCADO 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Paee 2 Time span--0.00-999.00 hrs, dt=0.01 hrs, 99901 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: Detention System 1 DA A Pond 2P: Detention System 1 Subcatchment 3S: Detention System 2 DA B Pond 4P: Detention System 2 Subcatchment 5S: Detention System Bypass DA C Link 6L: Site Outfall Subcatchment 7S: Drainage Area 2 Link 8L: Site Outfall Runoff Area=0.837 ac 82.80% Impervious Runoff Depth=2.17" Tc=5.0 min CN=92 Runoff=3.20 cfs 0.151 of Peak Elev=512.57' Storage=5,420 cf Inflow=3.20 cfs 0.151 of Outflow=0.02 cfs 0.151 of Runoff Area=1.610 ac 87.64% Impervious Runoff Depth=2.26" Tc=5.0 min CN=93 Runoff=6.33 cfs 0.304 of Peak Elev=500.14' Storage=13,074 cf Inflow=6.35 cfs 0.455 of Outflow=0.03 cfs 0.455 of Runoff Area=0.370 ac 0.00% Impervious Runoff Depth=0.37" Tc=5.0 min CN=61 Runoff--0.19 cfs 0.011 of Inflow=0.21 cfs 0.466 of Primary=0.21 cfs 0.466 of Runoff Area=0.397 ac 21.16% Impervious Runoff Depth=0.68" Tc=5.0 min CN=69 Runoff--0.47 cfs 0.022 of h flow=0.47 cfs 0.022 of Primary=0.47 cfs 0.022 of Post Dev Post Dev Type II24-hr 1-Year Rainfall=3.01 " Prepared by Shimp Engineering, P.C. Printed 4/l/2022 HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Paee 3 Summary for Subcatchment 1S: Detention System 1 DA A (Managed) Runoff = 3.20 cfs @ 11.96 his, Volume= 0.151 af, Depth= 2.17" Runoff by SCS TR-20 method, UH=SCS, Time Span-- 0.00-999.00 firs, dt= 0.01 his Type H 24-hr 1-Year Rainfall=3.01" 0.693 98 Paved parking, HSG B * 0.144 61 >75% Grass cover, Good, HSG B 0.837 92 Weighted Average 0.144 17.20% Pervious Area 0.693 82.80% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Pond 2P: Detention System 1 Inflow Area = 0.837 ac, 82.80% Impervious, Inflow Depth = 2.17" for 1-Year event Inflow = 3.20 cfs @ 11.96 firs, Volume= 0.151 of Outflow = 0.02 cfs @ 24.04 firs, Volume= 0.151 af, Atten= 99%, Lag-- 724.6 min Primary = 0.02 cfs @ 24.04 firs, Volume= 0.151 of Routing by Stor-Ind method, Time Span-- 0.00-999.00 firs, dt= 0.01 hrs Peak Elev= 512.57' @ 24.04 firs Surf.Area= 1,925 sf Storage= 5,420 cf Plug -Flow detention time= 2,461.2 min calculated for 0.151 of (100% of inflow) Center -of -Mass det. time= 2,461.2 min ( 3,257.2 - 795.9 ) Volume Invert Avail.Storage Storage Description #1 509.00' 10,006 cf 84.0" D x 130.0'L (2)130LF - 84" CMP x 2 #2 509.00' 577 cf 84.0" D x 5.0'L (3) 5LF - 84" CMP x 3 10,583 cf Total Available Storage Device Routing Invert Outlet Devices #1 Primary 505.58' 18.0" Round 18" HDPE Pipe Lr 8.8' Ke= 0.600 Inlet / Outlet Invert= 505.58' / 505.14' S= 0.0500 7 Cc= 0.900 n= 0.012 #2 Device 1 509.00' 0.7" Vert. 0.7" Orifice C= 0.600 #3 Device 1 513.40' 18.0" Round 18" HDPE Pipe Lr 26.5' Ke= 0.600 Inlet / Outlet Invert= 513.40' / 513.40' S= 0.0000 7 Cc= 0.900 n= 0.012 Primary Outflow Max--0.02 cfs @ 24.04 firs HW=512.57' (Free Discharge) t1=18" HDPE Pipe (Passes 0.02 cfs of 19.92 cfs potential flow) L2=0.7" Orifice (Orifice Controls 0.02 cfs @ 9.06 fps) 3=18" HDPE Pipe ( Controls 0.00 cfs) Post Dev Post Dev Type II24-hr 1-Year Rainfall=3.01 " Prepared by Shimp Engineering, P.C. Printed 4/l/2022 HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Paee 4 Summary for Subcatchment 3S: Detention System 2 DA B (Managed) Runoff = 6.33 cfs @ 11.96 hrs, Volume= 0.304 af, Depth= 2.26" Runoff by SCS TR-20 method, UH=SCS, Time Span-- 0.00-999.00 hrs, dt= 0.01 hrs Type H 24-hr 1-Year Rainfall=3.01" 1.411 98 Paved parking, HSG B * 0.199 61 >75% Grass cover, Good, HSG B 1.610 93 Weighted Average 0.199 12.36% Pervious Area 1.411 87.64% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Pond 4P: Detention System 2 Inflow Area = 2.447 ac, 85.98% Impervious, Inflow Depth = 2.23" for 1-Year event Inflow = 6.35 cfs @ 11.96 hrs, Volume= 0.455 of Outflow = 0.03 cfs @ 24.14 hrs, Volume= 0.455 af, Atten=100%, Lag-- 730.9 min Primary = 0.03 cfs @ 24.14 hrs, Volume= 0.455 of Routing by Stor-Ind method, Time Span-- 0.00-999.00 hrs, dt= 0.01 hrs Peak Elev= 500.14' @ 24.14 hrs Surf.Area= 3,411 sf Storage= 13,074 cf Plug -Flow detention time= 5,697.4 min calculated for 0.455 of (100% of inflow) Center -of -Mass det. time= 5,697.4 min ( 7,308.6 - 1,611.2 ) Volume Invert Avail.Storage Storage Description #1 495.50' 3,870 cf 96.0" D x 77.0'L (1) 77 LF - 96" CMP #2 495.50' 10,556 cf 96.0" D x 210.0'L (1) 210 LF - 96" CMP #3 495.50' 754 cf 96.0" D x 5.0'L (3) 5 LF - 96" Pipe Storage x 3 #4 495.50' 6,535 cf 96.0" D x 130.0'L (1)130 LF - 96" CP 21,715 cf Total Available Storage Device Routing Invert Outlet Devices #1 Primary 495.48' 24.0" Round 24" HDPE Pipe Lr 20.0' Ke= 0.600 Inlet / Outlet Invert= 495.48' / 494.50' S= 0.0490 'f Cc= 0.900 n= 0.012 #2 Device 1 495.50' 0.7" Vert. 0.7" Orifice C= 0.600 #3 Device 1 500.30' 18.0" Round 18" HDPE Pipe Lr 5.0' Ke= 0.600 Inlet / Outlet Invert= 500.30' / 500.30' S= 0.0000 7 Cc= 0.900 n= 0.012 #4 Device 1 501.32' 24.0" Round 24" HDPE Pipe Lr 19.0' Ke= 0.600 Inlet / Outlet Invert= 501.32' / 500.00' S= 0.0695 7 Cc= 0.900 n= 0.012 Post Dev Post Dev Type II24-hr 1-Year Rainfall=3.01 " Prepared by Shimp Engineering, P.C. Printed 4/l/2022 HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Paee 5 Primary Outflow Max--0.03 cfs @ 24.14 hrs HW=500.14' (Free Discharge) L =24" HDPE Pipe (Passes 0.03 cfs of 27.15 cfs potential flow) 2=0.7" Orifice (Orifice Controls 0.03 cfs @ 10.34 fps) 3=18" HDPE Pipe ( Controls 0.00 cfs) =24" HDPE Pipe ( Controls 0.00 cfs) Summary for Subcatchment 5S: Detention System Bypass DA C (Unmanaged) Runoff = 0.19 cfs @ 11.99 firs, Volume= 0.011 af, Depth= 0.37" Runoff by SCS TR-20 method, UH=SCS, Time Span-- 0.00-999.00 hrs, dt= 0.01 his Type H 24-hr 1-Year Rainfall=3.01" 0.370 61 >75% Grass cover, Good, HSG B 0.370 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, TOC Summary for Link 6L: Site Outfall Inflow Area = 2.817 ac, 74.69% Impervious, Inflow Depth = 1.99" for 1-Year event Inflow = 0.21 cfs @ 11.99 firs, Volume= 0.466 of Primary = 0.21 cfs @ 11.99 firs, Volume= 0.466 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span-- 0.00-999.00 hrs, dt= 0.01 firs Summary for Subcatchment 7S: Drainage Area 2 Runoff = 0.47 cfs @ 11.97 firs, Volume= 0.022 af, Depth= 0.68" Runoff by SCS TR-20 method, UH=SCS, Time Span-- 0.00-999.00 hrs, dt= 0.01 hrs Type H 24-hr 1-Year Rainfall=3.01" Area (ac) CN Description 0.084 98 Paved parking, HSG B 0.313 61 >75% Grass cover, Good, HSG B 0.397 69 Weighted Average 0.313 78.84% Pervious Area 0.084 21.16% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, TOC Post Dev Post Dev Type II24-hr 1-Year Rainfall=3.01 " Prepared by Shimp Engineering, P.C. Printed 4/l/2022 HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Paee 6 Summary for Link 8L: Site Outfall Inflow Area = 0.397 ac, 21.16% Impervious, Inflow Depth = 0.68" for 1-Year event Inflow = 0.47 cfs @ 11.97 hrs, Volume= 0.022 of Primary = 0.47 cfs @ 11.97 hrs, Volume= 0.022 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span-- 0.00-999.00 hrs, dt= 0.01 hrs Post Dev Post Dev Type II 24-hr 10-Year Rainfall=5.51 " Prepared by Shimp Engineering, P.C. Printed 4/l/2022 HydroCADO 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Paee 7 Time span--0.00-999.00 hrs, dt=0.01 hrs, 99901 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: Detention System 1 DA A Pond 2P: Detention System 1 Subcatchment 3S: Detention System 2 DA B Pond 4P: Detention System 2 Subcatchment 5S: Detention System Bypass DA C Link 6L: Site Outfall Subcatchment 7S: Drainage Area 2 Link 8L: Site Outfall Runoff Area=0.837 ac 82.80% Impervious Runoff Depth=4.59" Tc=5.0 min CN=92 Runoff=6.42 cfs 0.320 of Peak Elev=513.98' Storage=8,055 cf Inflow=6.42 cfs 0.320 of Outflow=0.89 cfs 0.320 of Runoff Area=1.610 ac 87.64% Impervious Runoff Depth=4.70" Tc=5.0 min CN=93 Runoff--12.51 cfs 0.631 of Peak Elev=501.22' Storage=16,613 cf Inflow=12.54 cfs 0.951 of Outflow=2.39 cfs 0.951 of Runoff Area=0.370 ac 0.00% Impervious Runoff Depth=1.69" Tc=5.0 min CN=61 Runoff=1.15 cfs 0.052 of Inflow=2.56 cfs 1.003 of Primary=2.56 cfs 1.003 of Runoff Area=0.397 ac 21.16% Impervious Runoff Depth=2.34" Tc=5.0 min CN=69 Runoff=1.73 cfs 0.077 of Inflow=1.73 cfs 0.077 of Primary=1.73 cfs 0.077 of Post Dev Post Dev Type II 24-hr 10-Year Rainfall=5.51 " Prepared by Shimp Engineering, P.C. Printed 4/l/2022 HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Paee 8 Summary for Subcatchment 1S: Detention System 1 DA A (Managed) Runoff = 6.42 cfs @ 11.96 his, Volume= 0.320 af, Depth= 4.59" Runoff by SCS TR-20 method, UH=SCS, Time Span-- 0.00-999.00 firs, dt= 0.01 his Type H 24-hr 10-Year Rainfall=5.51" 0.693 98 Paved parking, HSG B * 0.144 61 >75% Grass cover, Good, HSG B 0.837 92 Weighted Average 0.144 17.20% Pervious Area 0.693 82.80% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Pond 2P: Detention System 1 Inflow Area = 0.837 ac, 82.80% Impervious, Inflow Depth = 4.59" for 10-Year event Inflow = 6.42 cfs @ 11.96 hrs, Volume= 0.320 of Outflow = 0.89 cfs @ 12.16 hrs, Volume= 0.320 af, Atten= 86%, Lag-- 12.1 min Primary = 0.89 cfs @ 12.16 hrs, Volume= 0.320 of Routing by Stor-Ind method, Time Span-- 0.00-999.00 firs, dt= 0.01 hrs Peak Elev= 513.98' @ 12.16 firs Surf.Area= 1,744 sf Storage= 8,055 cf Plug -Flow detention time=1,817.1 min calculated for 0.320 of (100% of inflow) Center -of -Mass det. time=1,817.2 min ( 2,592.5 - 775.4 ) Volume Invert Avail.Storage Storage Description #1 509.00' 10,006 cf 84.0" D x 130.0'L (2)130LF - 84" CMP x 2 #2 509.00' 577 cf 84.0" D x 5.0'L (3) 5LF - 84" CMP x 3 10,583 cf Total Available Storage Device Routing Invert Outlet Devices #1 Primary 505.58' 18.0" Round 18" HDPE Pipe Lr 8.8' Ke= 0.600 Inlet / Outlet Invert= 505.58' / 505.14' S= 0.0500 7 Cc= 0.900 n= 0.012 #2 Device 1 509.00' 0.7" Vert. 0.7" Orifice C= 0.600 #3 Device 1 513.40' 18.0" Round 18" HDPE Pipe Lr 26.5' Ke= 0.600 Inlet / Outlet Invert= 513.40' / 513.40' S= 0.0000 7 Cc= 0.900 n= 0.012 Primary Outflow Max--0.89 cfs @ 12.16 hrs HW=513.98' (Free Discharge) t1=18" HDPE Pipe (Passes 0.89 cfs of 22.06 cfs potential flow) L2=0.7" Orifice (Orifice Controls 0.03 cfs @ 10.71 fps) 3=18" HDPE Pipe (Barrel Controls 0.86 cfs @ 2.01 fps) Post Dev Post Dev Type II 24-hr 10-Year Rainfall=5.51 " Prepared by Shimp Engineering, P.C. Printed 4/l/2022 HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Paee 9 Summary for Subcatchment 3S: Detention System 2 DA B (Managed) Runoff = 12.51 cfs @ 11.96 hrs, Volume= 0.631 af, Depth= 4.70" Runoff by SCS TR-20 method, UH=SCS, Time Span-- 0.00-999.00 hrs, dt= 0.01 hrs Type H 24-hr 10-Year Rainfall=5.51" 1.411 98 Paved parking, HSG B * 0.199 61 >75% Grass cover, Good, HSG B 1.610 93 Weighted Average 0.199 12.36% Pervious Area 1.411 87.64% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Pond 4P: Detention System 2 Inflow Area = 2.447 ac, 85.98% Impervious, Inflow Depth = 4.66" for 10-Year event Inflow = 12.54 cfs @ 11.96 hrs, Volume= 0.951 of Outflow = 2.39 cfs @ 12.21 hrs, Volume= 0.951 af, Atten= 81%, Lag-- 15.0 min Primary = 2.39 cfs @ 12.21 hrs, Volume= 0.951 of Routing by Stor-Ind method, Time Span-- 0.00-999.00 hrs, dt= 0.01 hrs Peak Elev= 501.22' @ 12.21 hrs Surf.Area= 3,120 sf Storage= 16,613 cf Plug -Flow detention time= 3,282.7 min calculated for 0.951 of (100% of inflow) Center -of -Mass det. time= 3,282.8 min (4,667.1- 1,384.3 ) Volume Invert Avail.Storage Storage Description #1 495.50' 3,870 cf 96.0" D x 77.0'L (1) 77 LF - 96" CMP #2 495.50' 10,556 cf 96.0" D x 210.0'L (1) 210 LF - 96" CMP #3 495.50' 754 cf 96.0" D x 5.0'L (3) 5 LF - 96" Pipe Storage x 3 #4 495.50' 6,535 cf 96.0" D x 130.0'L (1)130 LF - 96" CP 21,715 cf Total Available Storage Device Routing Invert Outlet Devices #1 Primary 495.48' 24.0" Round 24" HDPE Pipe Lr 20.0' Ke= 0.600 Inlet / Outlet Invert= 495.48' / 494.50' S= 0.0490 'f Cc= 0.900 n= 0.012 #2 Device 1 495.50' 0.7" Vert. 0.7" Orifice C= 0.600 #3 Device 1 500.30' 18.0" Round 18" HDPE Pipe Lr 5.0' Ke= 0.600 Inlet / Outlet Invert= 500.30' / 500.30' S= 0.0000 7 Cc= 0.900 n= 0.012 #4 Device 1 501.32' 24.0" Round 24" HDPE Pipe Lr 19.0' Ke= 0.600 Inlet / Outlet Invert= 501.32' / 500.00' S= 0.0695 7 Cc= 0.900 n= 0.012 Post Dev Post Dev Type II 24-hr 10-Year Rainfall=5.51 " Prepared by Shimp Engineering, P.C. Printed 4/l/2022 HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Paee 10 Primary Outflow Max=2.38 cfs @ 12.21 firs HW=501.22' (Free Discharge) L =24" HDPE Pipe (Passes 2.38 cfs of 30.87 cfs potential flow) 2=0.7" Orifice (Orifice Controls 0.03 cfs @ 11.49 fps) 3=18" HDPE Pipe (Barrel Controls 2.35 cfs @ 2.97 fps) =24" HDPE Pipe ( Controls 0.00 cfs) Summary for Subcatchment 5S: Detention System Bypass DA C (Unmanaged) Runoff = 1.15 cfs @ 11.97 his, Volume= 0.052 af, Depth= 1.69" Runoff by SCS -IR-20 method, UH=SCS, Time Span-- 0.00-999.00 hrs, dt= 0.01 his Type H 24-hr 10-Year Rainfall=5.51" 0.370 61 >75% Grass cover, Good, HSG B 0.370 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, TOC Summary for Link 6L: Site Outfall Inflow Area = 2.817 ac, 74.69% Impervious, Inflow Depth = 4.27" for 10-Year event Inflow = 2.56 cfs @ 12.19 firs, Volume= 1.003 of Primary = 2.56 cfs @ 12.19 firs, Volume= 1.003 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span-- 0.00-999.00 hrs, dt= 0.01 hrs Summary for Subcatchment 7S: Drainage Area 2 Runoff = 1.73 cfs @ 11.96 firs, Volume= 0.077 af, Depth= 2.34" Runoff by SCS TR-20 method, UH=SCS, Time Span-- 0.00-999.00 firs, dt= 0.01 hrs Type H 24-hr 10-Year Rainfall=5.51" Area (ac) CN Description 0.084 98 Paved parking, HSG B 0.313 61 >75% Grass cover, Good, HSG B 0.397 69 Weighted Average 0.313 78.84% Pervious Area 0.084 21.16% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, TOC Post Dev Post Dev Type II 24-hr 10-Year Rainfall=5.51 " Prepared by Shimp Engineering, P.C. Printed 4/l/2022 HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Paee 11 Summary for Link 8L: Site Outfall Inflow Area = 0.397 ac, 21.16% Impervious, Inflow Depth = 2.34" for 10-Year event Inflow = 1.73 cfs @ 11.96 hrs, Volume= 0.077 of Primary = 1.73 cfs @ 11.96 hrs, Volume= 0.077 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span-- 0.00-999.00 hrs, dt= 0.01 hrs Post Dev Post Dev Type II24-hr 100-Year Rainfall=9.04" Prepared by Shimp Engineering, P.C. Printed 4/l/2022 HydroCADO 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Nee 12 Time span--0.00-999.00 hrs, dt=0.01 hrs, 99901 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: Detention System 1 DA A Pond 2P: Detention System 1 Subcatchment 3S: Detention System 2 DA B Pond 4P: Detention System 2 Subcatchment 5S: Detention System Bypass DA C Link 6L: Site Outfall Subcatchment 7S: Drainage Area 2 Link 8L: Site Outfall Runoff Area=0.837 ac 82.80% Impervious Runoff Depth=8.07" Tc=5.0 min CN=92 Runoff--10.90 cfs 0.563 of Peak Elev=515.67' Storage=10,400 cf Intow=10.90 cfs 0.563 of Outflow=8.79 cfs 0.563 of Runoff Area=1.610 ac 87.64% Impervious Runoff Depth=8.20" Tc=5.0 min CN=93 Runoff--21.08 cfs 1.100 of Peak Elev=503.25' Storage=21,514 cf Inflow=28.30 cfs 1.663 of Outflow=25.65 cfs 1.663 of Runoff Area=0.370 ac 0.00% Impervious Runoff Depth=4.26" Tc=5.0 min CN=61 Runoff=2.93 cfs 0.131 of Inflow=28.16 cfs 1.794 of Primary=28.16 cfs 1.794 of Runoff Area=0.397 ac 21.16% Impervious Runoff Depth=5.25" Tc=5.0 min CN=69 Runoff=3.81 cfs 0.174 of Inflow=3.81 cfs 0.174 of Primary=3.81 cfs 0.174 of Post Dev Post Dev Type II24-hr 100-Year Rainfall=9.04" Prepared by Shimp Engineering, P.C. Printed 4/l/2022 HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Nee 13 Summary for Subcatchment 1S: Detention System 1 DA A (Managed) Runoff = 10.90 cfs @ 11.96 his, Volume= 0.563 af, Depth= 8.07" Runoff by SCS TR-20 method, UH=SCS, Time Span-- 0.00-999.00 firs, dt= 0.01 his Type H 24-hr 100-Year Rainfall=9.04" 0.693 98 Paved parking, HSG B * 0.144 61 >75% Grass cover, Good, HSG B 0.837 92 Weighted Average 0.144 17.20% Pervious Area 0.693 82.80% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Pond 2P: Detention System 1 Inflow Area = 0.837 ac, 82.80% Impervious, Inflow Depth = 8.07" for 100-Year event Inflow = 10.90 cfs @ 11.96 hrs, Volume= 0.563 of Outflow = 8.79 cfs @ 12.00 hrs, Volume= 0.563 af, Atten=19%, Lag-- 2.8 min Primary = 8.79 cfs @ 12.00 hrs, Volume= 0.563 of Routing by Stor-Ind method, Time Span-- 0.00-999.00 firs, dt= 0.01 hrs Peak Elev= 515.67' @ 12.00 firs Surf.Area= 819 sf Storage= 10,400 cf Plug -Flow detention time= 1,064.6 min calculated for 0.563 of (100% of inflow) Center -of -Mass det. time=1,064.7 min (1,826.0 - 761.3 ) Volume Invert Avail.Storage Storage Description #1 509.00' 10,006 cf 84.0" D x 130.0'L (2)130LF - 84" CMP x 2 #2 509.00' 577 cf 84.0" D x 5.0'L (3) 5LF - 84" CMP x 3 10,583 cf Total Available Storage Device Routing Invert Outlet Devices #1 Primary 505.58' 18.0" Round 18" HDPE Pipe Lr 8.8' Ke= 0.600 Inlet / Outlet Invert= 505.58' / 505.14' S= 0.0500 7 Cc= 0.900 n= 0.012 #2 Device 1 509.00' 0.7" Vert. 0.7" Orifice C= 0.600 #3 Device 1 513.40' 18.0" Round 18" HDPE Pipe Lr 26.5' Ke= 0.600 Inlet / Outlet Invert= 513.40' / 513.40' S= 0.0000 7 Cc= 0.900 n= 0.012 Primary Outflow Max=8.77 cfs @ 12.00 hrs HW=515.66' (Free Discharge) t1=18" HDPE Pipe (Passes 8.77 cfs of 24.37 cfs potential flow) L2=0.7" Orifice (Orifice Controls 0.03 cfs @ 12.40 fps) 3=18" HDPE Pipe (Barrel Controls 8.74 cfs @ 4.94 fps) Post Dev Post Dev Type II24-hr 100-Year Rainfall=9.04" Prepared by Shimp Engineering, P.C. Printed 4/l/2022 HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Nee 14 Summary for Subcatchment 3S: Detention System 2 DA B (Managed) Runoff = 21.08 cfs @ 11.96 hrs, Volume= 1.100 af, Depth= 8.20" Runoff by SCS TR-20 method, UH=SCS, Time Span-- 0.00-999.00 hrs, dt= 0.01 hrs Type H 24-hr 100-Year Rainfall=9.04" 1.411 98 Paved parking, HSG B * 0.199 61 >75% Grass cover, Good, HSG B 1.610 93 Weighted Average 0.199 12.36% Pervious Area 1.411 87.64% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Pond 4P: Detention System 2 Inflow Area = 2.447 ac, 85.98% Impervious, Inflow Depth = 8.15" for 100-Year event Inflow = 28.30 cfs @ 11.97 hrs, Volume= 1.663 of Outflow = 25.65 cfs @ 12.00 hrs, Volume= 1.663 af, Atten= 9%, L.ag= 2.0 min Primary = 25.65 cfs @ 12.00 hrs, Volume= 1.663 of Routing by Stor-Ind method, Time Span-- 0.00-999.00 hrs, dt= 0.01 hrs Peak Elev= 503.25' @ 12.00 hrs Surf.Area= 1,200 sf Storage= 21,514 cf Plug -Flow detention time= 1,900.6 min calculated for 1.663 of (100% of inflow) Center -of -Mass det. time=1,900.7 min ( 3,020.2 - 1,119.5 ) Volume Invert Avail.Storage Storage Description #1 495.50' 3,870 cf 96.0" D x 77.0'L (1) 77 LF - 96" CMP #2 495.50' 10,556 cf 96.0" D x 210.0'L (1) 210 LF - 96" CMP #3 495.50' 754 cf 96.0" D x 5.0'L (3) 5 LF - 96" Pipe Storage x 3 #4 495.50' 6,535 cf 96.0" D x 130.0'L (1)130 LF - 96" CP 21,715 cf Total Available Storage Device Routing Invert Outlet Devices #1 Primary 495.48' 24.0" Round 24" HDPE Pipe Lr 20.0' Ke= 0.600 Inlet / Outlet Invert= 495.48' / 494.50' S= 0.0490 'f Cc= 0.900 n= 0.012 #2 Device 1 495.50' 0.7" Vert. 0.7" Orifice C= 0.600 #3 Device 1 500.30' 18.0" Round 18" HDPE Pipe Lr 5.0' Ke= 0.600 Inlet / Outlet Invert= 500.30' / 500.30' S= 0.0000 7 Cc= 0.900 n= 0.012 #4 Device 1 501.32' 24.0" Round 24" HDPE Pipe Lr 19.0' Ke= 0.600 Inlet / Outlet Invert= 501.32' / 500.00' S= 0.0695 7 Cc= 0.900 n= 0.012 Post Dev Post Dev Type II24-hr 100-Year Rainfall=9.04" Prepared by Shimp Engineering, P.C. Printed 4/l/2022 HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Nee 15 Primary OutFlow Max=25.61 cfs @ 12.00 hrs HW=503.25' (Free Discharge) L =24" HDPE Pipe (Passes 25.61 cfs of 36.89 cfs potential flow) 2=0.7" Orifice (Orifice Controls 0.04 cfs @ 13.38 fps) 3=18" HDPE Pipe (Inlet Controls 11.82 cfs @ 6.69 fps) =24" HDPE Pipe (Inlet Controls 13.75 cfs @ 4.43 fps) Summary for Subcatchment 5S: Detention System Bypass DA C (Unmanaged) Runoff = 2.93 cfs @ 11.96 firs, Volume= 0.131 af, Depth= 4.26" Runoff by SCS -IR-20 method, UH=SCS, Time Span-- 0.00-999.00 hrs, dt= 0.01 hrs Type H 24-hr 100-Year Rainfall=9.04" 0.370 61 >75% Grass cover, Good, HSG B 0.370 100.00%" Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, TOC Summary for Link 6L: Site Outfall Inflow Area = 2.817 ac, 74.69% Impervious, Inflow Depth = 7.64" for 100-Year event Inflow = 28.16 cfs @ 12,00 firs, Volume= 1.794 of Primary = 28.16 cfs @ 12.00 firs, Volume= 1.794 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span-- 0.00-999.00 hrs, dt= 0.01 firs Summary for Subcatchment 7S: Drainage Area 2 Runoff = 3.81 cfs @ 11.96 firs, Volume= 0.174 af, Depth= 5.25" Runoff by SCS TR-20 method, UH=SCS, Time Span-- 0.00-999.00 hrs, dt= 0.01 hrs Type H 24-hr 100-Year Rainfall=9.04" Area (ac) CN Description 0.084 98 Paved parking, HSG B 0.313 61 >75%" Grass cover, Good, HSG B 0.397 69 Weighted Average 0.313 78.84% Pervious Area 0.084 21.16% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, TOC Post Dev Post Dev Type II24-hr 100-Year Rainfall=9.04" Prepared by Shimp Engineering, P.C. Printed 4/l/2022 HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Nee 16 Summary for Link 8L: Site Outfall Inflow Area = 0.397 ac, 21.16% Impervious, Inflow Depth = 5.25" for 100-Year event Inflow = 3.81 cfs @ 11.96 hrs, Volume= 0.174 of Primary = 3.81 cfs @ 11.96 hrs, Volume= 0.174 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span-- 0.00-999.00 hrs, dt= 0.01 hrs 664 West Rio Energy Balance Equation Summary: Site Outfall 24 Hr 1 year Storm Comparison: Qe dwm!� I.F. *(Qm�dop .RvaB dw�))Rve drem Q&.1. m4(Qra *RV�m)/Rvd—I pm I.F. = 0.8 1.17 0.105 Max Qd,,.,bW =0.21 cfs 0.473 Limits of Disturbance QPre.aryewpm ac RV�o,,,�� = RV= = Achieved Post-Dev Max Runoff Qlyr = 0.21 cfs. Site complies with 9VAC25-870-66-B(3) Maximum Q10yr = 633 cfs (predev) Achieved Q10yr = 2.56 efs. Site complies with 9VAC25-870-66-C(2) I.F.= 1 0-8 FOR LDA> I AC I.F. 1 0-9 IFORIDA<lAC LDA= MMMffAC Flow Predev Flowrates Postdev Flowrates Reduction Check Storm cls Storm cfs 1-yr L21 1-yr 0.21 10-vr 6.53 10-yr 2.56 Predev Reduced Energy Balance Equation Compliance: Achieved NOTE: ALL SOILS IN DRAINAGE AREA 1 ARE HSG B I �— W. as—1 ooc --_—�-- O\\ I W 45-100B I II \ \\\ \ W. 45-1 J3 DASHED LINE RERREBENn NG wF ZONING OMSION RIOR8 FBC - FLEX i I I I II I I I I I 1 11 1 \ \ I \ 1 \ C 1 I 278 iHSG \\ o/ $IBSG `I IIj� 11 xV A\ A A 11 \I 1 1 \ I IG2 11 1 \\ `` YI \, \ \ I 1 \ 0000 f PIP ' IL1, I 1 1 1 1 1 'I ' aI <o^ ;; , �2 III j II I ; I 1 I / ` �HSG B I/ 4C \ `\ St / �/ i i %/ i I SITE ` \ HS \ B OUTFALL TTT _ \ / YY $ J• J n / I )Y% 11 ti 11111y11/II/II/II/II/II.1/II.II/Ilrlljll/II.II/II.II.� SI NNPEYNNEERING, PCr, , TM45-105 60 0 60 120 180 664 West Rio FN6AM,/N6.LANOPUNNN6-FROJECTKANA6MENNT ..�a.n—.. — ,=oo= . a N.�IgP-� t�Rl„ awM Post Development Inlet Drainage Area Map Scale: 1 "=so' 664 West Rio Inlets Drainage Area Summary Impervious C 0.9 Pervious C 0.3 Str. Type Str. No. Area Total % Imp Imp. (ft) Turf (ft) C Are 6' DI-3B C5 7,310 40% 2,924 4,386 0.54 0.17 6' DI-3B C4 4,510 65% 2,932 1,579 0.69 0.10 6' DI-3B C2 18,860 90% 16,974 1,886 0.84 0.43 6' DI-3B B2 16,388 90% 14,749 1,639 0.84 0.38 6' DI-3B E3 1,760 80% 1,408 352 0.78 0.04 8' DI-3B E2A 8,117 80% 6,494 1,623 0.78 0.19 6' DI-3B F2 16,901 90% 15,211 1,690 0.84 0.39 6' DI-3B G2 14,864 90% 13,378 1,486 0.84 0.34 664 West Rio LD-204 Stormwater Wet Computations 1 sm cr�rny Se0l sway E u? C 10 o [=A 19 20 21 �i o I 2 3 5 5 6 6 6 9 10 11 11 1 2 13 14 I S 16 1 ] IS 1 19 20 21 22 23 24 (0) (m) (mmr) (Ss) (ets) (ets) C/7 Cr) f/1 (fl) (fl) (ets) (ds) (R) (R) (R) C5 6DI-311 6'DI-3B 0.7 0.54 0.09 4.00 0.36 0." 036 0.015 0.020 0.100 0." 3.12 0.0] 95.9% 0.35 0.015 6.5 059 00" 0.59 3.75 0.08 81.8% 0.48 0.107 C4 6' DI-3B 6 DI-3B 0.10 0.69 00] 4.00 0.29 0.015 030 0.015 0.020 0.100 0." 191 0.06 99.1% 0.30 0.003 6.5 1 0.46 0.107 1 0.52 1 1 1 390 1 0.07 82.9% 1 0.47 1 RM C2 6' DI-3B 6 DI-3B 0A3 0." 036 cm 1.45 0.003 1." 0.015 0050 0.020 0.083 0.16 1.9] 6.50 2.36 0.098 I" 0.23 855 B2 6DI-311 6'DI-3B 0.38 0." 0.32 4.0 1.26 0.025 U9 0.015 0.015 0.014 0.083 0.15 1.81 6.5 205 0.170 2.22 0.22 ]02 E3 6DI-311 6'DI-3B 004 0.78 0.03 4.0 0.13 0." 0.13 0.015 0.020 0.100 0." 113 0.04 100.0% 0.13 0.000 6.5 0.20 0." 0.20 2.50 0.05 100.0% 0.20 0'" E2A 8'DI-311 8'DI-3B 0.19 0.78 0.15 4.0 0.58 0." 039 0.015 0.020 0.100 0." 3.73 0.0] 95.7% 0.56 0.@5 6.5 0.94 0." 0." 4.46 0.09 820% 0.]] 0.170 F2 6DI-311 6'DI-3B 0.39 0." 0.33 4.0 1.30 0.025 133 0.015 0.029 am 0." 0.15 1.82 6.5 2.12 0.170 2.29 0.21 6.37 02 6DI-311 6'DI-3B 0.34 0." 0.29 4.0 1.15 0." 1.15 0.015 0.014 0.@6 0." 0.14 1.68 6.5 1 1.86 8000 1 1.86 0.19 301 Notes: Q sfromstrot E2ABowstosuurtme B2 664 West Rio Storm Pipes Drainage Area Summary Impervious C 0.9 Pervious C 0.3 Str. Type Str. No. Areal `�o Imp Imp. (ft) Turf (ft) C Area (ae) 72" MH-1 to 48" MH-1 A4-A3 48" MH-1 to 48" MH-1 A3-A2 48" MH-1 to Outlet Protection A2-Al 6' DI-3B to 96" CMP B2-B1 16,388 90% 14,749 1,639 0.84 0.38 6' DI-3B to 6' DI-3B C5-C4 7,310 40% 2,924 4,386 0.54 0.17 6' DI-3B to 48" MH- 1 C4-C3 4,510 65% 2,932 1,579 0.69 0.10 48" MH-1 to 6' DI- 3B C3-C2 - - - - - 6' DI-3B to 96" CMP C2-C1 18,860 90% 16,974 1,886 0.84 0.43 60" MH-1 to 48" MH-1 D3-D2 - - - - - - 48" MH-1 to 96" CMP D2-Dl 6' DI-3B to 15" HDPE E3-E2 1,760 80% 1,408 352 0.78 0.04 8' DI-3B to 15" HDPE E2A-E2 8,117 80% 6,494 1,623 0.78 0.19 15" HDPE to 96" CMP El-E2 6' DI-3B to 84" CMP F2-Fl 16,901 90% 15,211 1,690 0.84 0.39 6' DI-3B to 84" CMP G2-G1 14,864 90% 13,378 1,486 0.84 0.34 664 West Rio LD-229 STORM DRAIN DESIGN COMPUTATIONS From To Catch. Runoff Inc Accum ToC Total Total UP Dn Pipe Inv Pipe Pipe Velocity Flow time Point Point Area Coef AC AC Intensity Plow (cfs) invert Invert Length Sloe 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 *A4 A3 - - - - - - 2.60 495.48 494.50 15.21 6.44% 24 62.19 9.78 - *A3 A2 - - - - - - 2.60 493.46 485.42 83.31 9.65% 24 76.13 11.27 - *A2 Al - - - - - - 2.60 485.22 482.57 67.53 3.92% 24 48.52 8.22 - B2 B1 0.38 0.84 0.32 0.38 5.00 5.17 1.94 500.42 500.00 12.21 3.44% 15 12.98 7.60 0.03 C5 C4 0.17 0.54 0.09 0.09 5.00 5.17 0.47 516.00 513.20 30.16 9.28% 15 21.32 7.08 0.07 C4 C3 0.10 0.69 0.07 0.16 5.07 5.15 0.83 513.00 504.17 113.55 7.78% 15 19.52 7.90 0.24 C3 C2 - - - 0.16 5.31 5.09 0.83 502.70 502.20 31.94 1.57% 15 8.77 4.50 0.12 C2 Cl 0.43 0.84 0. % 0.53 5.43 5.06 2.66 500.50 500.00 12.02 4.16% 15 14.27 8.90 0.02 *D3 D2 - - - - - - 2.60 505.45 505.00 8.79 5.12% 18 25.75 9.34 - *132 131 - - - - - - 2.60 501.01 500.00 12.73 7.93% 18 32.05 9.27 - E3 E2 0.04 0.78 0.03 0.03 5.00 5.00 0.16 500.85 500.48 7.43 5.00% 15 15.65 4.12 0.03 E2A E2 0.19 0.78 0.15 0.15 5.00 5.00 0.73 501.02 500.48 10.84 5.00% 15 15.65 6.51 0.03 **E2 El - - - O.18 5.06 5.06 0.89 500.48 500.00 9.57 5.00% 15 15.65 6.91 0.02 F2 FI 0.39 0.84 0.33 0.33 5.00 5.00 1.63 513.00 512.50 7.44 6.72% 15 18.14 9.16 0.01 G2 GI 0.34 0.84 0.29 0.29 5.00 5.00 1.43 514.00 512.50 19.36 7.75% 15 15.88 9.27 0.03 Notes: 'Total Flow for A structures and D structures is from 10-yr Hydrocad Calculations "Structure E2 has accumelated area from structure E3 and E2A Ci 0.9 Cp 0.3 a2 b2 a10 b10 106.02 1 15.51 1 161.6 1 18.73 SHIMP ENGINEERING, P.C. Design Focused Engineering Water Quality Calculations: Pre -Development VRRM Land -use Map Post -Development VRRM Land -use Map VRRM Redevelopment Spreadsheet - 1 VRRM Redevelopment Spreadsheet - 2 VRRM Redevelopment Spreadsheet - 3 ® PRE DEV IMP. PRE DEV TURF. _,_LOD ----SOILS NOTE: ALL SOILS IN DRAINAGE AREA 1 ARE HSG B SMIMPEYRNEERING, P.C. LN6AMNN-L4NDPLANNN6 -PRQIBCT KANAGEMFNT . a ns LL . - 2=oo= . aTN.s MP° 1 RIN .wM �—_ TM. 45-100C ` o ' —_ W • o LIMITS OF N TM, 45-100B DISTURBANCE A=3.13 AC DASHED NNE 1 �\ REP RE NPNG TIE I 20NING EA 1 I RI029 M R1029 FBC -CORE 1 ) OAEA (APPRM) I W W W W W W • W W WI W W W\ W W W W W W W W W W 1P11Y 'Y11 W W\ � yW W W � W W W W W W W W W W W• W W W 4 ' W W W` \� W W W W W W W W W W W W� I W1I W W ✓\ W -Y • W W W W W W W W W W W W W W W W W W� W W W WAIF W W W W W �'Y W W I W W W W •y WAY-W W W W W W W W W W W W W W W I W W Y. ... . wJ v' W W W W W W W W W W W W W W W W W W W W W W O W W W WI W W W W W _WII W W _W W �/W W W W W W W W W W W W W W W W W W W W IW W W WIP-F W W' W I W W W W W W W W W W W W W W W W W W Dli (T0M' � p R"Ed'Alro 1 W W O W W W W I W W W W W W W W W W W W W W W W W W I W yF�OWDWF�N- 3¢0 I1 1 WW WW WW WW WWW W W'Svt_:r- . WW �WW W WW �WW WW WW WW WWW WW WWW W 0 W �W WWW W; W W'`w , W W W W W W W W W W W W W W W ' W W -WF aW i W1�VI1 I W W W W W W W W W W W W W W W W W W IW W W W W W .HSG B W+ W IW W W W W W W W W W W W W W W W �W S(4�C6 ,� 9 W-V 10. . . . . 8 DR I IMK: W W W W W W W W Ci DRCP 27.M W .y W W W W _ W 30' &M� DB. 664 West Rio Pre Development VRRM Map TM. 45-105 60 0 Scale: 1 TM. 45-1J3 DITCH TM. 45-94B 'I 120 180 ® POST DEV IMP. POST DEV TURF. LOD ---- SOILS NOTE: ALL SOILS IN DRAINAGE AREA 1 ARE HSG B SHIMPEYRNEERING, P.C. LN6AMNN-L4NDPLANNN6 -PRQIBCT KANAGEMFNT .aams LLa. - 2=.o= rN.9 MP° 1 RIN .wM _�'-- 0 W. 45-100C I I I I \� y I T _ � LIMITS OF W. 45-100B DISTURBANCE I: Y`y' N. as-na A=3.13 AC ; DASHED LANE 1 ` • • 1 REPRESENTNG TIE. •\ ZING OIN4CN ` v RIM FBI FLEX PREA w • • y I R1029 MC — CORE . . a . . . . v jy MEA (AVVRO%.J • • . j�ojF' eI .. 1l • j Ilk y 00 s 450 y I . ` I V1� ` I : 3aC: •i : HSO B"f 664 West Rio Pre Development VRRM Map TM45-105 60 0 Scale: 1 60 120 180 DEQ Virginia Runoff Reduction Method Re -Development Compliance Spreadsheet - Version 3.0 132011 BMP Standards and Specifications 02013 Draft BMP Standards and Specifications data input cells Project Name: 664 West Rio Date: 3/30/2022 censtant values Linear Development Project? _ No calculation cells Site Information Post -Development Project (Treatment Volume and Loads) Enter Total Disturbed Area (acres) 4 3.13 Check., BMP Design Specifications List. 2013 Draft Stds & Specs Maximum reduction required.- Linear project? No The site's net increase in impervious cover (acres) is:®i. Land cover areas entered correctly? ✓ Post -Development ® Total disturbed area entered? ✓ Pre-ReDevelopment Land Cover (acres) A Soils BSoils CSails DSoils Totals Forest/Open Spare (acres) -- undisturbed farest/open space U'00 Managed Ted (acres) -- disturbed, graded for yards or other turf to be mowed/managed 3.03 3.03 Impervious Cover(acres) 0.10 0.10 3.13 Post -Development Land Cover (acres) A Soils BSoils CSails DSoils Totals Forest/Open Spare (acres) -- undisturbed, protected forest/open space or reforested land 0'00 Managed Ted (acres) -- disturbed, graded for yards or other turf to be mowed/managed 0.97 0.97 Impervious Cover(acres) 2.16 2.16 Area Check OK. OK. OK. OK. 3.13 Constants Runoff Coefficients (RV) Annual Rainfall (inches) 43 ASoils BSoils CSoils DSoils Target Randall Event(inchesl 1.00 Forest/Open Space 0.02 0.03 0.04 0.05 Total Phosphorus [TP) EMC(mg/L) 0.26 Managed Turf 0.15 0.20 0.22 0.25 Total Nitrogen [TN) EMC (mg/L) 1.86 Impervious Cover 0.95 0.95 0.95 0.95 Target TP Load (lb/acre/W) 0.41 Pi(unitless correction factor) a.% r • r •• g • '• • •' Land Cover Summary -Pre Land Coversummary-Post(Final) Land Cover Summary -Post Land Cover Summary -Post Pre-ReDevelopment Listed Adjusted' Port Ream, &New Impervious Past-ReDevelopment Post-Devebpment New Impervious Forest/Open Space Formt/Open Space Forest/Open Space Cover (acres) 0.00 0.00 Cover (acres) 0.00 Cover (acres) 0.00 Weighted Rv(forest) 0.00 0.00 Weighted Rv(forest) 0.00 Weighted Rv(forest) 0.00 %Forest 0% 0% %Forest 0% %Forest 0% Managed Turf Cover (acres) 3.03 0.97 Managed Turf Cover 097 Managed Turf Cover 0.97 (acres) (acres) Weighted Rv(turf) 0.20 0.20 Weighted Rv (uff) 0.20 Weighted Rv(turf) 0.20 %Managed Turf 97% 91% %Managed Turf 31% %Managed Turf 91% Impervious Cover (acres) 0.30 0.10 Impervious Cover (acres) 2.16 ReDev. Impervious 0.to New Impervious Cover 206 [over (acres) (rams( Rv(unpervious) 0.95 0.95 Rv(impervious) 0.95 Rv(imWMous) 0.95 Rv(imParvpus) 0.95 %Impervious 3% 9% %Impervious 69% %Impervious 9% Total Site Area (acres) 3.13 1.07 Final Site Area (acres) 3.13 Total ReDev. Site Area 107 (acres) site Be 0.22 0.27 Final Post Day Site Rv 0.72 RADav Site Rv 0.27 Treatment Volume and Nutrient Load Treatment Volume and Nutrient Load Port -Development Final Port -Development Port-ReDevelopment omen Pre-ReOevelo [Trea[meM Volume 0.0584 0.0241 Trentment Volume 0.1872 Treatment Volume OA241 Treatment Volume 0.1631 (acre-R) (acre-R) (acre-R) (acre-R) Past -Development Pre-ReDevelo t Treatment Volume omen Final Pert -Development Port-ReDevelopment 2,545 1,049 Treatment Volume 8,153 TreatmentVolume 1,049 Treatment Volume (cubic 7,104 (whit feet) (cubic feet) (cubicfeet) feet) Post -Development TP Load Pre-ReDevelopment TP Load Final Port- Port-ReDevelopment Ubfurl 1.60 0.66 Development TP Load 5.12 Load (TP) 0.66 9.46 (Ibfur) (Ib/yr) pb/yr)• Prr•Renevelopment TP Load per acre Final Pose -Development TP Po4NenevelopmentW (Ib/aare/v,) os1 0,62 mad per acre 1.64 toad Par acre 0.62 (lb/acre/Yr) (lb/.m/w) Baseline TP mad (lb/yr) May. Reduction Required (a.41lhs/acre/yr applied to pre -redevelopment area excluding pervious 0.44 (Below Pre- 20% land proposed for new Impervious cover) ReDevelopment bad) 'AdustedWed CoyerSumma / re TP Load Reduction TP Load Reduction Pre ReDevelopment land rover minuspervious land cover OoresVopen space ormanaged Required for 0.13 Required for New 3.62 turf/ acreageprol osedfornew impervious cover. Redeveloped Area Impervious Area (Ib/yr) (Ib/yr) Adjusted total acreage is consistent with Post-ReDevelopment acreage (micas aaeoge of new impervious roverl. Column l shows load reduction requnemeatfor new impervious cover (based on new development mod limit, 0.41 @s/aae/yead. Post-Development Load Reduction Required (Ib/yr) 3.75 Nitrogen Loads (Informational Purposes Only) Pos[-Development TN mad Pre-ReDevelopment TN Load(lb/yr) 11.44 :::JFinal (Post-ReDevelopment&New Impervious) 36.65 (lb/yr) Site Results (Water Quality Compliance) Area Checks D.A.A D.A.0 D.A.0 D.AD D.AE AREACHECK FOREST/OPEN SPACE(ac) 1 0.00 0.00 0.00 0.00 0.00wo, IMPERVIOUS COVER(ac) 0.00 0.00 0.00 0.00 0.00IMPERVIOUS COVER TREATED(ac) 0.00 0.00 0.000.00 0.00MANAGED TURF AREA(ac) 0.00 0.00 HE 0.00 0.00MANAGED TURF AREA TREATED(ac) 0.00 0.00 0.00 0.00 0.00 AREA [HECK OK. OK. OK. OK. OK. Site Treatment Volume (fta) R,153 Runoff Reduction Volume and TP By Drainage Area D.A. A O.A. B D.A. C D.A. D I D.A. E TOTAL RUNOFF REDUCTIONVOLUME ED(W)� 0 .0 0 0 OVAL TP LOAD AVAllAB1E FOR REMOVAL (lb/yr) 0.00 0.00 0.00 0.00 0.00 0.00 TP LOAD REDUCTION ACHIEVED (Ib/yr) 0.00 0.00 0.00 0.00 0.00 0.00 TPLOADREMAINING (Ib/yr) 0.00 0.00 0.00 0.00 0.00 0.00 NITROGEN LOAD REDUCTION ACHIEVED (Ib/yr) 0.00 0.00 0.00 0.00 0.00 0.00 Total Phosphorus FINAL POST-DEVELOPMENTTP MAD (lb/yr)l 5.12 TP LOAD REDUCTION REQUIRED(Ib/yr) 3.75 TP LOAD REDUCTION ACHIEVED(Ib/yr) 0.00 TP LOAD REMAINING (Ib/yr): 5.12 REMAINING TP LOAD REDUCTION REQUIRED (Ib/yr): 3.75 Total Nitrogen (For Information Purposes) POST -DEVELOPMENT LOAD(Ib/yr) F 36.65 NITROGEN LOAD REDUCTION ACHIEVED (Ib/yr) 0.00 REMAINING POST -DEVELOPMENT NITROGEN LOAD(Ib/yr) 36.65 en,. Russ Rgxtim... wa.,. DEq ViMinla Runoa Reduction Method! Re- a elopment Compliance Spreadsheet - Version 3.0 RMPCesryn 111i roam s list: 2013 cmm.du 8 Spe¢ Site Summary Protect TNk: 664 west Rio Date strap Total Winded (in) C3 Totalmounted Ronde, I3.13 Site Wind Cover Summary nuelnmm.nt I antl.— mrn[I A dolls 1 atolls 1 C3ols DSalls i Totals eadrate, Foret/Open(acres) am 1 am] I Oro I Man 1,O.00 0 Managed Turf Dare[( 0.. 303 ON ON 3.03 91 Impervious C.—(arv( O.CO 010 ON ON 0.10 3 3.13 N Post-ReDevelopment Wind Cover lateral AWIs Bsolls CEaIB DStlls Decals %af.I Foren/Open (acres) 0.00 C W Dan OOT 0.00 0 Managed Turf Dares( am 097 Dan Man 0.97 31 Impervious Con—(arv( am 1 216 1 Dan Man 216 69 3.13 N Site Tv and Wind Cover Nutrient Wads Final PoxawelDeebelPpmmnt IPov-R MvbPmen[ Dvpod, .,.Pa. pIey_ elopmeM R aPamwd Ixme lmpeme.al sne Rn D.n 0,27 m9s a.n Treatlnxtt Valame(na( 8Jet Lm9 7104 Imes TP Wed In/p) S.Sz D. 646 DRD T 1 TP Lna6 Re6utlm RpuYM(IW,) 1 3.75 0.13 362 Final Part-Developereart a6 pre. (Po6RWwebpnen[ a New lmpwvlwn) ReDewlopment Tx Wed(e/yr) 1 3065 11M Site Compliance Summary Mmm.m%memo Raewree Ybu Drydapmm W.e Total RunoHVolume Reduction (fit?) 0 Total TP toad deduction A 1—d(IWW) 0.00 1.1 Tel toad Reduction .1—d Oww) 0.00 Remalnlry Port Development TP Load 12 Dww) Nematodes n lead Reductlon(IWW) 3.25 Requl" Drainage Area Summary Pre ..Oevebpmen[ FIr vracmeM Port -Wad eracrent lP TP Loa6 padre TPWad TP Wad pare[ LoaEPMare Ie acre r IIB/a[reMlre Ile/acre/yrl 0.62 1.6i 0.62 DAA DAB DAC DAD DAC Total Fweu/Open(arn) Ron O.Oo 1 ado 000 am O.oO Managm Tud(ares) Om I ..no IO.m om om O.m Impselouseowvprn) I Om 0.00 Om ow om O.m *oel At.( —,I I . a.m o.m Wo Dm a.m Drainage Area Compliance Summary DAA DAB 1 DAC DAD DAE TtlM rl Reduced(M1a/yrl Om ..Do D. 0d0 0m Om IN Wed Reduced (Ieter) 0m 0.m 0.m ono om 0m Runoff Volume and CN Calculations 1-yearamn 2,var Mtm 10-,at. re,etmmrar..,anl am am mm 0.aYweAreas Nv is CN DnMye WeaA DmInMe AreaB Dtfinage AreaC Drainage AreaD DrarMe Area a de (te) 1-year Mum id ped mlwaanl wrarunj Dre R. Red dre ROD am es adierned 2-year Mum period wmlwaanl dre ROD am awararea4nj are ROD am es adiernal 10,ear rtum Revised wmlwaanl dre ROD am awararea4nj dre ROD am es adiernal Sine., Ftim SHIMP ENGINEERING, P.C. Design Focused Engineering Independent Reports: Excerpt from NRCS Soils Report NOAA Precipitation Report W 57N W WN 3 Hydrologic Soil Group —Albemarle County, Virginia 3 !O Ih A tr� _I q 38'5VN M310 M340 W370 M400 M430 7214 721400 3 3 NMap Scale: S: AWfprirsd on A portrait (8.5' z 11")sleet N Pt�s `IN 0 20 40 80 121 /V 0 50 100 200 300 Map projection: Web Maomr Conamadinates:WGS84 Edgetis:UlMZme17NWG584 USDA Natural Resources Web Soil Survey 4/1/2022 Conservation Service National Cooperative Soil Survey Page 1 of 4 MAPLEGEND Area of Interest (A01) 0 Area of Interest A01) Solis Soil Rating Polygons 0 A Q AID o B Q B/D o C 0 CID 0 D 0 Not rated or not available Soil Rating Lines . r A ,y AID rV B ram/ B/D N C N CID i D . . Not rated or not available Soil Rating Points A Q AID O B 0 B/D Hydrologic Soil Group —Albemarle County, Virginia 0 C CID D 13 Not rated or not available Water Features Streams and Canals Transportation µ� Rails N Interstate Highways �y US Routes Major Roads Local Roads Background . Aerial Photography MAP INFORMATION The soil surveys that comprise your AC I 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 15, Sep 13, 2021 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Jun 8, 2020---Sep 23, 2020 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 4/1/2022 Conservation Service National Cooperative Soil Survey Page 2 of 4 Hydrologic Soil Group —Albemarle County, Virginia Hydrologic Soil Group Map unit symbol Map unit name Rating Acres in AOI Percent of AOI 27B Elioak loam, 2 to 7 percent slopes B 1.2 26.6% 27C Elioak loam, 7 to 15 percent slopes B 2.8 62.0% 34C Glenelg loam, 7 to 15 percent slopes B 0.5 11.4% Totals for Area of Interest 4.5 100.0% 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. Natural Resources Web Soil Survey 4/1/2022 Conservation Service National Cooperative Soil Survey Page 3 of 4 Hydrologic Soil Group —Albemarle County, Virginia Rating Options Aggregation Method: Dominant Condition Component Percent Cutoff.- None Specified Tie -break Rule: Higher Natural Resources Web Soil Survey 4/1/2022 Conservation Service National Cooperative Soil Survey Page 4 of 4 2124122, 8:53 AM Precipitation Frequency Data Server NOAA Atlas 14, Volume 2, Version 3 Location name: Charlottesville Virginia, USA* E Latitude: 38.0844°, Longitude:-78.4763° Elevation: 529.69 ft" ' source: ESRI Maps "source: USGS POINT PRECIPITATION FREQUENCY ESTIMATES G.M. Bonnin, D. Martin, B. Lin, T. Pa2ybok, 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 50 100 200 500 1000 0.352 0.419 0.492 0.553 0.623 0.678 0.729 0.778 0.837 0.884 5-min (g 317-0.390) (0.379-0.465) (0.443-0.545) (0.497-0.612) (0.558-0.688) (0.604-0.747) (0.645-0.803) (0.684-0.857) (0.728-0.924) (0.762-0.981) 0.562 0.671 0.789 0.885 0.994 1.08 1.16 1.23 1.32 1.39 10-min F� (0.506-0.623) (0.605-0.744) (0.710-0.873) (0.795-0.979) (0.889-1.10) (0.961-1.19) 1 (1.03-1.28) 1 (1.08-1.36) 1 (1.15-1A6) 1 (1.20-1.54) O. 0.843 0.998 1.12 1.26 1.37 1.46 1.56 1.67 1.75 15-min (0.633-0.779) (0.761-0.935) (0.898-1.11) 1 (1.01-1.24) 1 (1.13-1.39) 1 (1.22-1.51) 1 (1.30-1.61) 1 (1.37-1.71) 1 (1.45-1.84) 1 (1.51-1.94) 0.962 1.16 1.42 1.62 1.87 2.06 2.24 2.42 2.65 2.83 30-min (0.868-1.07) 1 (1.05-1.29) 1 (1.28-1.57) 1 (1.46-1.79) 1 (1.67-2.06) 1 (1.83-2.27) 1 (1.99-2.47) 1 (2.13-2.67) 1 (2.31-2.93) 1 (2.44-3.14) 1.20 1.46 1.82 2.11 2.48 2.79 3.09 3.40 3.80 4.13 60-min (1.08-1.33) 1 (1.32-1.62) 1 (1.64-2.01) 1 (1.90-2.34) 1 (2.22-2.74) 1 (2.48-3.07) 1 (2.74-3.40) 1 (2.99-3.74) 1 (3.31-4.20) 1 (3.56-4.58) 1.44 1.75 2.19 2.58 3.07 3.48 3.91 4.35 4.97 5.50 2-hr (1.27-1.64) 1 (1.54-1.99) 1 (1.93-2.49) 1 (2.27-2.92) 1 (2.68-3.47) 1 (3.03-3.94) 1 (3.38-4.41) 1 (3.73-4.91) 1 (4.22-5.62) 1 (4.61-6.23) 1.58 1.92 2.40 2.81 3.35 3.81 4.28 4.77 5.45 6.04 3-hr (1.39-1.81) 1 (1.68-2.20) 1 (2.10-2.75) 1 (2.45-3.21) 1 (2.91-3.83) 1 (3.29-4.34) 1 (3.67-4.87) 1 (4.06-5.44) 1 (4.58-6.22) 1 (5.02-6.90) 2.01 2.43 3.02 3.56 4.27 4.90 5.56 6.28 7.30 8.19 6-hr (1.78-2.28) 1 (2.15-2.76) 1 (2.66-3.42) 1 (3.12-4.02) 1 (3.73-4.83) 1 (4.24-5.52) 1 (4.77-6.27) (5.32-7.08) 1 (6.10-8.23) 1 (6.75-9.26) 2.53 3.05 3.80 4.50 5.48 6.34 7.29 8.32 9.86 11.2 12-hr (2.23-2.89) 1 (2.69-3.49) 1 (3.35-4.35) 1 (3.94-5.13) 1 (4.76-6.23) 1 (5.46-7.20) 1 (6.19-8.26) (6.98-9.43) 1 (8.11-11.2) 1 (9.09-12.8) 3.01 3.65 4.66 5.51 6.77 7.84 9.04 10.4 12.3 14.0 24-hr (2.71-3.38) 1 (3.28-4.10) 1 (4.17-5.23) 1 (4.92-6.16) 1 (6.00-7.55) 1 (6.91-8.73) 1 (7.89-10.0) 1 (8.94-11.5) 1 (10.5-13.6) 1 (11.7-15.5) 3.55 4.31 5.48 6.44 7.84 9.01 10.3 11.7 13.7 15.4 2-day (3.19-3.97) (3.87,4.82) (4.91-6.12) (5.76-7.18) (6.95-8.71) (7.93-9.99) (8.96-11.4) (10.1-13.0) (11.7-15.3) (13.0-17.1) 3.78 4.59 5.83 6.85 8.32 9.56 10.9 12.4 14.5 16.3 3-day (3.44-4.20) 1 (4.16-5.08) 1 (5.28-6.45) 1 (6.18-7.57) 1 (7.48-9.19) 1 (8.53-10.5) 1 (9.65-12.0) 1 (10.9-13.6) 1 (12.6-16.0) 1 (13.9-18.0) 4.01 4.87 6.18 7.25 8.81 10.1 11.5 13.1 15.3 17.1 4-day (3.68-4.42) 1 (4.45-5.35) 1 (5.65-6.79) 1 (6.61-7.96) 1 (8.00-9.66) 1 (9.13-11.1) 1 (10.3-12.6) 1 (11.6-14.3) 1 (13.4-16.8) 1 (14.9-18.9) 4.67 5.62 7.02 8.18 9.83 11.2 12.7 14.3 16.5 18.4 7-day P� (4.29-5.10) 1 (5.16-6.14) 1 (6.44-7.67) 1 (7.48-8.93) 1 (8.94-10.7) 1 (10.1-12.2) 1 (11.4-13.8) 1 (12.7-15.6) 1 (14.6-18.1) 1 (16.1-20.3) 5.30 6.35 7.85 9.05 10.8 12.2 13.6 15.2 17.4 19.2 10day F� (4.88-5.73) 1 (5.87-6.88) 1 (7.23-8.49) 1 (8.33-9.79) 1 (9.85-11.6) 1 (11.1-13.1) 1 (12.3-14.7) 1 (13.7-16.4) 1 (15.5-18.9) 1 (16.9-20.9) 6.95 8.29 10.0 11.4 13.2 14.7 16.1 17.6 19.7 21.3 20i18y P� (6.51-7.45) 1 (7.76-8.89) 1 (9.36-10.7) 1 (10.6-12.2) 1 (12.3-14.1) 1 (13.6-15.7) 1 (14.9-17.3) 1 (16.2-18.9) 1 (17.9-21.2) 1 (19.3-23.0) 8.53 10.1 12.0 13.4 15.2 16.6 17.9 19.3 21.0 22.4 30-day (8.03-9.09) 1 (9.52-10.8) 1 (11.2-12.7) 1 (12.5-14.2) 1 (14.2-16.2) 1 (15.5-17.7) 1 (16.7-19.1) 1 (17.9-20.6) 1 (19.4-22.5) 1 (20.5-24.0) 10.6 12.B 14.7 16.3 18.3 19.8 21.3 22.7 24.5 25.8 45ilay (10.1-11.3) 1 (11.9-13.3) 1 (13.9-15.6) 1 (15.4-17.2) 1 (17.2-19.4) 1 (18.6-21.0) 1 (19.9-22.6) 1 (21.2-24.1) 1 (22.7-26.1) (23.9-27.5) 12.5 14.7 17.0 16.7 20.8 22.4 23.9 25.4 27.2 28.5 60-day (11.8-13.2) (13.9-15.5) (16.1-17.9) (17.6-19.7) (19.7-22.0) (21.1-23.6) (22.5-25.3) (23.8-26.8) (25.4-28.8) (26.5-30.2) 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/hdsc/pfds/pfds_printpage.html?lat=38.0844&Ion=-78.4763&data=depth&units=english&series=pds#maps 1/4