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Home My WebLink AboutWPO202000037 Calculations WPO VSMP 2020-07-02July 2, 2020 Engineering Review Albemarle County Department of Community Development 401 McIntire Road Charlottesville, VA 22902 Regarding: WPO 2020xxxxx Galaxie Farm Subdivision – VSMP Plan SWM Calculation Packet Dear Reviewer, Enclosed is the stormwater calculation packet for the Galaxie Farm Subdivision VSMP Plan. The project is a private redevelopment of a site to create a subdivision served by public roads. The main purpose of stormwater design for this site is to route offsite runoff safely through the site into the perennial stream, Cow Branch, which flows through the site. Runoff Quantity Narrative The runoff from this development is released into Cow Branch in compliance with quantity regulations detailed in 9VAC25-870-66-B (channel protection) and 9VAC25-870-66-B (flood protection). Specifically, this is achieved by diverting the majority of the site to point of analysis (POA) A, a location in Cow Branch near the upstream end of the site where both Storm Sewer System E and Culvert G outlet. This location was selected as an storm sewer outlet due to the topography and layout of the developed site (bypassing offsite runoff around the proposed lots suggested sewer placement in the ROW) and to minimize disturbance within the WPO stream buffer. Storm Sewer System E achieves 2 major design objectives: safely bypass the significant amount of offsite runoff through the site, and to route some of the onsite and offsite runoff into a Stormtech BMP to achieve nutrient treatment and stormwater detention. The offsite runoff comes from adjacent properties which include the Avinity subdivision, Cale Elementary, Albemarle Health & Rehabilitation Center, and residential land owned by Albemarle County. At POA A, the development increases the total drainage area, runoff volume, and flow rate at that point in the stream compared to the predeveloped conditions. To address this increase in runoff at POA 1, we will pursue compliance with 9VAC25-870-66-B(2): Restored stormwater conveyance systems. When stormwater from a development is discharged to a restored stormwater conveyance system that has been restored using natural design concepts, following the land- disturbing activity, either: a. The development shall be consistent, in combination with other stormwater runoff, with the design parameters of the restored stormwater conveyance system that is functioning in accordance with the design objectives; or b. The peak discharge requirements for concentrated stormwater flow to natural stormwater conveyance systems in subdivision 3 of this subsection shall be met. Cow Branch has been observed by members of Shimp Engineering Staff to have evidence of channel erosion and overtopped banks along the site, making it a candidate for channel restoration. Thus, to address subsection 2 1 of the code above, portions of the onsite Cow Branch stream channel will be restored using natural design concepts to a point where the flow requirements in subsection 3 (compliance with energy balance equation, and reduction of the 10-yr runoff at a POA) are met. POA 2 is the point at which the runoff complies with 9VAC25-870-66-B(3)a (the energy balance equation) and 9VAC25-870-66-C(2)b (10-yr flood protection). POA 2 is the outlet of Culverts A & B and Storm Sewer System C & D. At this point, the runoff detention provided by the BMP affects the hydrology in the stream to reduce the overall runoff by rates that exceed state requirements. POA 3 is a final analysis of all runoff through the site at the point where Cow Branch leaves the development property. Here, the runoff complies with 9VAC25-870-66-B(3)a and 9VAC25-870-66-C(2)b as the runoff reduction provided by the SWM design exceeds the reduction required by the energy balance equation, and the 10-yr storm runoff is also reduced. Thus, all runoff quantity requirements for this development are achieved. Runoff Quality Narrative To address runoff quality requirements set forth in 9VAC25-870-65, the site land cover information was input into the VRRM Redevelopment Spreadsheet Version 3. 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 8.78 lb/yr. Specific to this development, ZMA 201800012 requires that 25% of the total nutrient treatment must be provided with onsite BMP measures. To achieve required TP reduction, we have selected a Stormtech BMP with an isolator row that achieves 40% TP removal to treat a portion of runoff which flows through the site. The Stormtech BMP will treat 2.22 lb/yr TP, which corresponds to a 25.3% treatment rate and satisfies the ZMA condition. The remaining 6.56 lb/yr TP reduction will be met with a purchase of phosphorous credits for that amount. This, all runoff quality requirements for this development are achieved. Other SWM Calculations The culverts which lie under Road A, which serves as the only subdivision entrance, were designed for the 25-yr storm. To size the culverts, the VDOT Inlet Control Headwater Depth nomograph was used. The flows used in this nomograph resulted from the Southern Peidmont Rural Regression Equation, which is a VDOT- accepted runoff calculation for road design. All other VDOT public storm sewer calculation requirements for inlets and capacity are also shown herein. If you have any questions about this calculation packet please do not hesitate to contact me at: keane@shimp-engineering.com or by phone at 434-299-9843. Regards, Keane Rucker, EIT Shimp Engineering, PC 2 Contents: SWM Quantity Requirements: Drainage Area Spreadsheet Pre-Dev Small POA Drainage Map Pre-Dev Large POA Drainage Map Post-Dev Small POA Drainage Map Post-Dev Large POA Drainage Map TOC Calcs & Nomographs – Seelye, Fig. 15-4, & Kirpitch TOC Calcs – NEH Lag Method Pre-Dev Total HydroCAD Report Pre-Dev Onsite For EBE HydroCAD Report Post-Dev Total HydroCAD Report Post-Dev Onsite For EBE HydroCAD Report Energy Balance Equations SWM Quality Requirements: Pre-Dev VRRM Map Post-Dev VRRM Map VRRM Re-Development Spreadsheet Other SWM Calculations Drainage Area Spreadsheet (Repeat) Post-Dev Culvert Drainage Map Post-Dev Inlet Drainage Map Post-Dev Inlet Drainage Map (Offsite Included) Rural Regression Equations for Culvert Sizing VDOT Appendix 8C-2 Inlet Control Nomograph for Culvert Sizing VDOT LD-204 Inlet Capacity VDOT LD-229 Storm Drain Capacity VDOT LD-268 Ditch Capacity VDOT LD-347 Hydraulic Grade Line VDOT Outlet Protection Nomograph ESCP Calculations: Sediment Basin Design Spreadsheet Sediment Basin Design Nomographs Independent Reports: Excerpt from NRCS Soils Report NOAA Precipitation Report 3 SWM Quantity Requirements: Drainage Area Spreadsheet Pre-Dev Small POA Drainage Map Pre-Dev Large POA Drainage Map Post-Dev Small POA Drainage Map Post-Dev Large POA Drainage Map TOC Calcs & Nomographs – Seelye, Fig. 15-4, & Kirpitch TOC Calcs – NEH Lag Method Pre-Dev Total HydroCAD Report Pre-Dev Onsite For EBE HydroCAD Report Post-Dev Total HydroCAD Report Post-Dev Onsite For EBE HydroCAD Report Energy Balance Equations 4 SWM Quality Requirements: Pre-Dev VRRM Map Post-Dev VRRM Map VRRM Re-Development Spreadsheet 5 Other SWM Calculations Drainage Area Spreadsheet (Repeat) Post-Dev Culvert Drainage Map Post-Dev Inlet Drainage Map Post-Dev Inlet Drainage Map (Offsite Included) Rural Regression Equations for Culvert Sizing VDOT Appendix 8C-2 Inlet Control Nomograph for Culvert Sizing VDOT LD-204 Inlet Capacity VDOT LD-229 Storm Drain Capacity VDOT LD-268 Ditch Capacity VDOT LD-347 Hydraulic Grade Line VDOT Outlet Protection Nomograph 6 ESCP Calculations: Sediment Basin Design Spreadsheet Sediment Basin Design Nomographs 7 Independent Reports: Excerpt from NRCS Soils Report NOAA Precipitation Report 8 Galaxie Farm Inlet Drainage Area Summary Impervious C 0.9 Pervious C 0.3 Woods C 0.2 To Inlet Area Impervious Turf C A G2 10,943,095 2,188,619 8,754,476 0.42 251.22 F4 18,600 11,440 7,160 0.67 0.43 F3 27,270 13,700 13,570 0.60 0.63 F2 1,248,870 90,432 1,158,439 0.34 28.67 F1 00 0 0 0.71 0.00 E9 468,399 132,173 336,226 0.47 10.75 E8A 20,483 14,310 6,173 0.72 0.47 E8 39,982 19,230 20,752 0.59 0.92 E7C 1,702,368 510,710 1,191,657 0.22 39.08 E7A 10,746 7,344 3,402 0.71 0.25 E7 19,955 9,973 9,982 0.60 0.46 E6Z 00 0 0 0.30 0.00 E6A 17,762 12,437 5,325 0.72 0.41 E6 29,652 12,140 17,512 0.55 0.68 E5 55,189 26,235 28,954 0.59 1.27 E4 6,430 5,100 1,330 0.78 0.15 E3 17,780 12,446 5,334 0.72 0.41 E2 26,021 16,731 9,290 0.69 0.60 D3 51,625 18,486 33,139 0.51 1.19 D2 22,451 8,890 13,561 0.54 0.52 C3 12,692 10,935 1,757 0.82 0.29 C2 6,038 5,570 468 0.85 0.14 B2 14,726,791 3,092,626 11,634,165 0.43 338.08 A2 5,802,223 1,160,445 4,641,778 0.42 133.20 Ditch 1 159,704 38,751 120,953 0.45 3.67 9 248.23 AC TOTAL DA TO POA 1 474.61 AC TOTAL DRAINAGE AREA @ POA 2 0.63 AC ONSITE TO POA 1 11.90 AC ONSITE TO POA 2 POA 2 POA 1 POA 3 475.44 AC DRAINAGE AREA TO POA 3 7S 2S 10S 5S 3S 11S 8S 4L 9L 11L1S GALAXIE FARM PREDEV SMALL POA DRAINAGE MAPTOTAL DRAINAGE TO POA 1 = 248.23 AC ALL HSG B. INCLUDES THE FOLLOWING SUBCATCHMENTS: 1S: ONSITE TO POA 1 (11.6 MIN TOC) 0.22 AC WOODS 0.03 AC IMP 0.38 AC FARM TURF 2S: OFFSITE TO POA 1 NORTH OF RTE 20 (TOC V) 89.91 AC 1 3 ACRE LOTS @ 30% IMPERVIOUS 3S: OFFSITE TO POA 1 SOUTH OF RTE 20 (TOC VI) 157.69 AC WOODS/GRASS COMBO @ CN=58 4L: POA 1 TOTAL DRAINAGE TO POA 2 = 474.61 AC ALL HSG B. INCLUDES DRAINAGE TO POA 1 PLUS THE FOLLOWING SUBCATCHMENTS: 5S: ONSITE TO POA 2 (18.7 MIN TOC) 2.98 AC WOODS 0.57 AC IMP 8.35 AC FARM TURF 6S: OFFSITE TO POA 2 NORTH OF SITE (TOC III) 59.70 AC 1 3 ACRE LOTS @ 30% IMPERVIOUS 7S: OFFSITE TO POA 2 NORTHEAST OF SITE (TOC I) 20.84 AC WOODS/GRASS COMBO @ CN=59 8S: OFFSITE TO POA 2 SOUTH OF SITE (TOC VII) 133.94 AC WOODS/GRASS COMBO @ CN=59 9L: POA 2 TOTAL DRAINAGE TO POA 3 = 475.44 AC ALL HSG B. INCLUDES DRAINAGE TO POA 1 & 2 PLUS THE FOLLOWING SUBCATCHMENTS: 10S: ONSITE TO POA 3 (11.2 MIN TOC) 0.83 AC WOODS/GRASS COMBO @ CN=58 11L: POA 3 10 248.23 AC TOTAL DA TO POA 1 474.61 AC TOTAL DRAINAGE AREA @ POA 2 0.63 AC ONSITE TO POA 1 11.90 AC ONSITE TO POA 2 POA 2 POA 1 POA 3 475.44 AC DRAINAGE AREA TO POA 3 TOC V TO C I TOC III T O C V I I TOC V I 7S 6S 6S 2S 10S 5S 3S 11S 8S 4L 9L 11L1S GALAXIE FARM PREDEV LARGE POA DRAINAGE MAP TOTAL DRAINAGE TO POA 1 = 248.23 AC ALL HSG B. INCLUDES THE FOLLOWING SUBCATCHMENTS: 1S: ONSITE TO POA 1 (11.6 MIN TOC) 0.22 AC WOODS 0.03 AC IMP 0.38 AC FARM TURF 2S: OFFSITE TO POA 1 NORTH OF RTE 20 (TOC V) 89.91 AC 1 3 ACRE LOTS @ 30% IMPERVIOUS 3S: OFFSITE TO POA 1 SOUTH OF RTE 20 (TOC VI) 157.69 AC WOODS/GRASS COMBO @ CN=58 4L: POA 1 TOTAL DRAINAGE TO POA 2 = 474.61 AC ALL HSG B. INCLUDES DRAINAGE TO POA 1 PLUS THE FOLLOWING SUBCATCHMENTS: 5S: ONSITE TO POA 2 (18.7 MIN TOC) 2.98 AC WOODS 0.57 AC IMP 8.35 AC FARM TURF 6S: OFFSITE TO POA 2 NORTH OF SITE (TOC III) 59.70 AC 1 3 ACRE LOTS @ 30% IMPERVIOUS 7S: OFFSITE TO POA 2 NORTHEAST OF SITE (TOC I) 20.84 AC WOODS/GRASS COMBO @ CN=59 8S: OFFSITE TO POA 2 SOUTH OF SITE (TOC VII) 133.94 AC WOODS/GRASS COMBO @ CN=59 9L: POA 2 TOTAL DRAINAGE TO POA 3 = 475.44 AC ALL HSG B. INCLUDES DRAINAGE TO POA 1 & 2 PLUS THE FOLLOWING SUBCATCHMENTS: 10S: ONSITE TO POA 3 (11.2 MIN TOC) 0.83 AC WOODS/GRASS COMBO @ CN=58 11L: POA 3 11 474.47 AC TOTAL DRAINAGE AREA TO POA 2 R O A D C 54 ' R O W POA 2 POA 1336.76 AC TOTAL AREA TO POA 1 POA 3 1.13 AC ONSITE TO BMP 1 2S 5S 6S 7S 8S 14S 4S 1S 9S 11S 12S 10L 13L 15L 3P 475.44 AC TOTAL DRAINAGE AREA TO POA 3 GALAXIE FARM POSTDEV SMALL POA DRAINAGE MAP TOTAL DRAINAGE TO POA 1 = 336.76 AC ALL HSG B. INCLUDES THE FOLLOWING SUBCATCHMENTS: 1S: ONSITE TO BMP 1 VIA F3&F4 (5 MIN ASSUMED TOC) 0 AC WOODS 0.50 AC IMP 0.63 AC TURF 2S: OFFSITE TO BMP 1 VIA F2 (TOC I) 19.70 AC WOODS 2.22 AC IMP 4.80 AC TURF 3P: BMP 1 4S: ONSITE TO POA 1 (5 MIN ASSUMED TOC) 0.30 AC WOODS 3.51 AC IMP 3.57 AC TURF 5S: OFFSITE TO BMP 1 VIA F2 (TOC II) 12.61 AC 1 3 ACRE LOTS @ 30% IMPERVIOUS 6S: OFFSITE TO BMP 1 VIA F2 (TOC III) 38.52 AC 1 3 ACRE LOTS @ 30% IMPERVIOUS 7S: OFFSITE TO POA 1 VIA DITCH 1 (TOC IV) 2.84 AC 1 2 ACRE LOTS @ 25% IMPERVIOUS 8S: OFFSITE TO POA 1 VIA G2 (TOC V) 89.86 AC 1 3 ACRE LOTS @ 30% IMPERVIOUS 9S: OFFSITE TO POA 1 VIA G2 (TOC VI) 157.70 AC WOODS/GRASS COMBO @ CN=58 10L: POA 1 TOTAL DRAINAGE TO POA 2 = 474.47 AC ALL HSG B. INCLUDES DRAINAGE TO POA 1 PLUS THE FOLLOWING SUBCATCHMENTS: 11S: ONSITE TO POA 2 (5 MIN ASSUMED TOC) 1.50 AC WOODS 1.22 AC IMP 1.50 AC TURF 12S: OFFSITE TO POA 2 VIA A2 (TOC VII) 133.49 AC WOODS/GRASS COMBO @ CN=58 13L: POA 2 TOTAL DRAINAGE TO POA 3 = 475.44 AC ALL HSG B. INCLUDES DRAINAGE TO POA 1 & 2 PLUS THE FOLLOWING SUBCATCHMENTS: 14S: ONSITE TO POA 3 (5 MIN ASSUMED TOC) 0.50 AC WOODS 0.47 AC TURF 15L: POA 3 12 474.47 AC TOTAL DRAINAGE AREA TO POA 2 R O A D C 54 ' R O W TOC V TOC I V POA 2 POA 1336.76 AC TOTAL AREA TO POA 1 TO C I T O C I I TOC III T O C V I I TOC V I POA 3 1.13 AC ONSITE TO BMP 1 2S 5S 6S 7S 8S 14S 4S 1S 9S 11S 12S 10L 13L 15L 3P 475.44 AC TOTAL DRAINAGE AREA TO POA 3 GALAXIE FARM POSTDEV LARGE POA DRAINAGE MAP TOTAL DRAINAGE TO POA 1 = 336.76 AC ALL HSG B. INCLUDES THE FOLLOWING SUBCATCHMENTS: 1S: ONSITE TO BMP 1 VIA F3&F4 (5 MIN ASSUMED TOC) 0 AC WOODS 0.50 AC IMP 0.63 AC TURF 2S: OFFSITE TO BMP 1 VIA F2 (TOC I) 19.70 AC WOODS 2.22 AC IMP 4.80 AC TURF 3P: BMP 1 4S: ONSITE TO POA 1 (5 MIN ASSUMED TOC) 0.30 AC WOODS 3.51 AC IMP 3.57 AC TURF 5S: OFFSITE TO BMP 1 VIA F2 (TOC II) 12.61 AC 1 3 ACRE LOTS @ 30% IMPERVIOUS 6S: OFFSITE TO BMP 1 VIA F2 (TOC III) 38.52 AC 1 3 ACRE LOTS @ 30% IMPERVIOUS 7S: OFFSITE TO POA 1 VIA DITCH 1 (TOC IV) 2.84 AC 1 2 ACRE LOTS @ 25% IMPERVIOUS 8S: OFFSITE TO POA 1 VIA G2 (TOC V) 89.86 AC 1 3 ACRE LOTS @ 30% IMPERVIOUS 9S: OFFSITE TO POA 1 VIA G2 (TOC VI) 157.70 AC WOODS/GRASS COMBO @ CN=58 10L: POA 1 TOTAL DRAINAGE TO POA 2 = 474.47 AC ALL HSG B. INCLUDES DRAINAGE TO POA 1 PLUS THE FOLLOWING SUBCATCHMENTS: 11S: ONSITE TO POA 2 (5 MIN ASSUMED TOC) 1.50 AC WOODS 1.22 AC IMP 1.50 AC TURF 12S: OFFSITE TO POA 2 VIA A2 (TOC VII) 133.49 AC WOODS/GRASS COMBO @ CN=58 13L: POA 2 TOTAL DRAINAGE TO POA 3 = 475.44 AC ALL HSG B. INCLUDES DRAINAGE TO POA 1 & 2 PLUS THE FOLLOWING SUBCATCHMENTS: 14S: ONSITE TO POA 3 (5 MIN ASSUMED TOC) 0.50 AC WOODS 0.47 AC TURF 15L: POA 3 13 GALAXIE FARM PREDEV TOC NOMOGRAPHS 14 GALAXIE FARM PreDev Time of Concentration Calculations 100 ft overland flow 9.0%slope 0.35 C-value 10.2 min Seelye Chart 99 ft s. c. flow-grass 3.0%slope 1.2 fps velocity 1.4 min.NEH Figure 15-4 00 ft channel 0.0 ft height 0.0 min.Kirpich Chart TOC= 11.6 min. Predev to POA 2 100 ft overland flow 10.3%slope 0.35 C-value 9.8 min Seelye Chart 212 ft s. c. flow-grass 14.6%slope 2.6 fps velocity 1.4 min.NEH Figure 15-4 1175 ft channel 30.0 ft height 7.5 min.Kirpich Chart TOC= 18.7 min. Predev to POA 3 100 ft overland flow 13.0%slope 0.35 C-value 9.5 min Seelye Chart 208 ft s. c. flow-woods 16.3%slope 2.0 fps velocity 1.7 min.NEH Figure 15-4 00 ft ditch 0 ft height 0.0 min.Kirpich Chart TOC= 11.2 min. Predev to POA 1 15 GALAXIE FARM POSTDEV TOC NOMOGRAPHS 16 GALAXIE FARM PostDev Time of Concentration Calculations 100 ft overland flow 2.0%slope 0.35 C-value 13.2 min Seelye Chart 390 ft s. c. flow-woods 6.4%slope 1.3 fps velocity 5.0 min.NEH Figure 15-4 849 ft channel 30.0 ft height 5.3 min.Kirpich Chart TOC= 23.5 min. TOC II: POSTDEV TO E9 / POST OFFSITE TO POA 1 (5S) 100 ft overland flow 4.0%slope 0.35 C-value 12.9 min Seelye Chart 476 ft s. c. flow-woods 6.3%slope 1.3 fps velocity 6.3 min.NEH Figure 15-4 810 ft channel 56.0 ft height 4.0 min.Kirpich Chart TOC= 23.2 min. TOC IV: POSTDEV TO DITCH 1 / POST OFFSITE TO POA 1 (7S) 100 ft overland flow 5.0%slope 0.35 C-value 12.2 min Seelye Chart 298 ft s. c. flow-woods 15.6%slope 1.9 fps velocity 2.6 min.NEH Figure 15-4 121 ft ditch 1 ft height 1.7 min.Kirpich Chart TOC= 16.5 min. TOC I: POSTDEV TO F2 / POST OFFSITE TO BMP 1 (2S) 17 GALAXIE FARM Offsite Time of Concentration Calculations λ=2138 flow length elevations:highest= 624 lowest= 486 Y=6.5% Avg Watershed Slope cn=72 curve number S=3.889 Max Retention Tc=0.484 hrs TOC=29.0 min. λ=4926 flow length elevations:highest= 692 lowest= 467.5 Y=4.6% Avg Watershed Slope cn=72 curve number S=3.889 Max Retention Tc=1.122 hrs TOC=67.3 min. TOC VI: POSTDEV TO B2 / POST OFFSITE TO POA 1 (9S) λ=6920 flow length elevations:highest= 1588 lowest= 467.5 Y=16.2% Avg Watershed Slope cn=58 curve number S=7.241 Max Retention Tc=1.126 hrs TOC=67.6 min. TOC VII: POSTDEV TO A2 / POST OFFSITE TO POA 2 (12S) λ=5098 flow length elevations:highest= 1581 lowest= 465 Y=21.9% Avg Watershed Slope cn=58 curve number S=7.241 Max Retention Tc=0.759 hrs TOC=45.5 min. TOC III: POSTDEV TO E7C / POST OFFSITE TO POA 1 (6S) TOC V: POSTDEV TO G2 / POST OFFSITE TO POA 1 (8S) NEH 630.1502 (a) TOC - Watershed Lag Method = .∗(+1). 1140 ∗. 18 Chapter 15 15–5(210–VI–NEH, May 2010) Time of Concentration Part 630 National Engineering Handbook 630.1502 Methods for estimating time of concentration Two primary methods of computing time of concentra- tion were developed by the Natural Resources Conser- vation Service (NRCS) (formerly the Soil Conservation Service (SCS)). (a) Watershed lag method The SCS method for watershed lag was developed by Mockus in 1961. It spans a broad set of conditions ranging from heavily forested watersheds with steep channels and a high percent of runoff resulting from subsurface ﬂow, to meadows providing a high retar- dance to surface runoff, to smooth land surfaces and large paved areas. L S Y =+()A 0 8 0 7 0 5 1 1 900 .. ., (eq. 15–4a) Applying equation 15–3, L=0.6Tc, yields: T S Yc= +( ) A0 8 0 7 0 5 1 1 140 .. ., (eq. 15–4b) where: L = lag, h Tc = time of concentration, h A = ﬂow length, ft Y = average watershed land slope, % S = maximum potential retention, in =-1 000 10, cn where: cn = the retardance factor Flow length (A )—In the watershed lag method of computing time of concentration, ﬂow length is de- ﬁned as the longest path along which water ﬂows from the watershed divide to the outlet. In developing the regression equation for the lag method, the longest ﬂow path was used to represent the hydraulically most distant point in the watershed. Flow length can be measured using aerial photographs, quadrangle sheets, or GIS techniques. Mockus (USDA 1973) developed an empirical relationship between ﬂow length and drain- age area using data from Agricultural Research Service (ARS) watersheds. This relationship is: A =209 0 6A. (eq. 15–5) where: A = ﬂow length, ft A = drainage area, acres Land slope (Y), percent—The average land slope of the watershed, as used in the lag method, not to be confused with the slope of the ﬂow path, can be deter- mined in several different ways: • by assuming land slope is equal to a weighted average of soil map unit slopes, determined us- ing the local soil survey • by using a clinometer for ﬁeld measurement to determine an estimated representative average land slope • by drawing three to four lines on a topographic map perpendicular to the contour lines and de- termining the average weighted slope of these lines • by determining the average of the land slope from grid points using a dot counter • by using the following equation (Chow 1964): Y CI A = ()100 (eq. 15–6) where: Y = average land slope, % C = summation of the length of the contour lines that pass through the watershed drainage area on the quad sheet, ft I = contour interval used, ft A = drainage area, ft2 (1 acre = 43,560 ft2) Retardance factor—The retardance factor, cn´, is a measure of surface conditions relating to the rate at which runoff concentrates at some point of interest. The term “retardance factor” expresses an inverse relationship to “ﬂow retardance.” Low retardance fac- tors are associated with rough surfaces having high de- grees of ﬂow retardance, or surfaces over which ﬂow will be impeded. High retardance factors are associ- ated with smooth surfaces having low degrees of ﬂow retardance, or surfaces over which ﬂow moves rapidly. 19 1S ONSITE TO POA 1 2S OFFSITE TO POA 1 (NORTH OF RTE 20, TOC V) 3S OFFSITE TO POA 1 (SOUTH OF RTE 20, TOC VI) 4L POA 1 5S ONSITE TO POA 2 6S OFFSITE TO POA 2 (NORTH OF SITE, TOC III) 7S OFFSITE TO POA 2 (NORTHEAST OF SITE, TOC I) 8S OFFSITE TO POA 2 (SOUTH OF SITE, TOC VII) 9L POA 2 10S ONSITE SHEETFLOW 11L POA 3 (COW BRANCH) Drainage Diagram for PREDEV TOTAL Prepared by Shimp Engineering, P.C., Printed 7/2/2020 HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Subcat Reach Pond Link 20 PREDEV TOTAL Type II 24-hr 1-YR Rainfall=3.04"PREDEV TOTAL Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 2HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC 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 Runoff Area=0.630 ac 4.76% Impervious Runoff Depth=0.65"Subcatchment 1S: ONSITE TO POA 1 Tc=11.6 min CN=68 Runoff=0.52 cfs 0.034 af Runoff Area=89.910 ac 30.00% Impervious Runoff Depth=0.83"Subcatchment 2S: OFFSITE TO POA 1 Tc=67.3 min CN=72 Runoff=32.00 cfs 6.234 af Runoff Area=157.690 ac 0.00% Impervious Runoff Depth=0.29"Subcatchment 3S: OFFSITE TO POA 1 Tc=67.6 min CN=58 Runoff=11.42 cfs 3.769 af Inflow=42.73 cfs 10.037 afLink 4L: POA 1 Primary=42.73 cfs 10.037 af Runoff Area=11.900 ac 4.79% Impervious Runoff Depth=0.74"Subcatchment 5S: ONSITE TO POA 2 Tc=18.7 min CN=70 Runoff=8.87 cfs 0.730 af Runoff Area=59.700 ac 30.00% Impervious Runoff Depth=0.83"Subcatchment 6S: OFFSITE TO POA 2 Tc=29.0 min CN=72 Runoff=39.15 cfs 4.139 af Runoff Area=20.840 ac 0.00% Impervious Runoff Depth=0.32"Subcatchment 7S: OFFSITE TO POA 2 Tc=23.5 min CN=59 Runoff=3.41 cfs 0.550 af Runoff Area=133.940 ac 0.00% Impervious Runoff Depth=0.29"Subcatchment 8S: OFFSITE TO POA 2 Tc=45.5 min CN=58 Runoff=12.07 cfs 3.201 af Inflow=72.40 cfs 18.658 afLink 9L: POA 2 Primary=72.40 cfs 18.658 af Runoff Area=0.830 ac 0.00% Impervious Runoff Depth=0.29"Subcatchment 10S: ONSITE SHEETFLOW Tc=11.2 min CN=58 Runoff=0.18 cfs 0.020 af Inflow=72.45 cfs 18.678 afLink 11L: POA 3 (COW BRANCH) Primary=72.45 cfs 18.678 af Total Runoff Area = 475.440 ac Runoff Volume = 18.678 af Average Runoff Depth = 0.47" 90.43% Pervious = 429.957 ac 9.57% Impervious = 45.483 ac 21 PREDEV TOTAL Type II 24-hr 1-YR Rainfall=3.04"PREDEV TOTAL Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 3HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: ONSITE TO POA 1 Runoff = 0.52 cfs @ 12.05 hrs, Volume= 0.034 af, Depth= 0.65" 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=3.04" Area (ac) CN Description 0.380 73 Small grain, contoured, Good, HSG B 0.220 55 Woods, Good, HSG B * 0.030 98 Impervious 0.630 68 Weighted Average 0.600 95.24% Pervious Area 0.030 4.76% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 11.6 Direct Entry, Summary for Subcatchment 2S: OFFSITE TO POA 1 (NORTH OF RTE 20, TOC V) Runoff = 32.00 cfs @ 12.79 hrs, Volume= 6.234 af, Depth= 0.83" 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=3.04" Area (ac) CN Description 89.910 72 1/3 acre lots, 30% imp, HSG B 62.937 70.00% Pervious Area 26.973 30.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 67.3 Direct Entry, Summary for Subcatchment 3S: OFFSITE TO POA 1 (SOUTH OF RTE 20, TOC VI) Runoff = 11.42 cfs @ 13.01 hrs, Volume= 3.769 af, Depth= 0.29" 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=3.04" Area (ac) CN Description 157.690 58 Woods/grass comb., Good, HSG B 157.690 100.00% Pervious Area 22 PREDEV TOTAL Type II 24-hr 1-YR Rainfall=3.04"PREDEV TOTAL Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 4HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 67.6 Direct Entry, Summary for Link 4L: POA 1 Inflow Area = 248.230 ac, 10.88% Impervious, Inflow Depth = 0.49" for 1-YR event Inflow = 42.73 cfs @ 12.83 hrs, Volume= 10.037 af Primary = 42.73 cfs @ 12.83 hrs, Volume= 10.037 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Summary for Subcatchment 5S: ONSITE TO POA 2 Runoff = 8.87 cfs @ 12.14 hrs, Volume= 0.730 af, Depth= 0.74" 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=3.04" Area (ac) CN Description 8.350 73 Small grain, contoured, Good, HSG B 2.980 55 Woods, Good, HSG B * 0.570 98 Impervious 11.900 70 Weighted Average 11.330 95.21% Pervious Area 0.570 4.79% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 18.7 Direct Entry, Summary for Subcatchment 6S: OFFSITE TO POA 2 (NORTH OF SITE, TOC III) Runoff = 39.15 cfs @ 12.26 hrs, Volume= 4.139 af, Depth= 0.83" 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=3.04" Area (ac) CN Description 59.700 72 1/3 acre lots, 30% imp, HSG B 41.790 70.00% Pervious Area 17.910 30.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 29.0 Direct Entry, 23 PREDEV TOTAL Type II 24-hr 1-YR Rainfall=3.04"PREDEV TOTAL Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 5HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Subcatchment 7S: OFFSITE TO POA 2 (NORTHEAST OF SITE, TOC I) Runoff = 3.41 cfs @ 12.26 hrs, Volume= 0.550 af, Depth= 0.32" 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=3.04" Area (ac) CN Description * 20.840 59 Woods/grass combo 2, Good, HSG B 20.840 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 23.5 Direct Entry, Summary for Subcatchment 8S: OFFSITE TO POA 2 (SOUTH OF SITE, TOC VII) Runoff = 12.07 cfs @ 12.63 hrs, Volume= 3.201 af, Depth= 0.29" 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=3.04" Area (ac) CN Description 133.940 58 Woods/grass comb., Good, HSG B 133.940 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 45.5 Direct Entry, Summary for Link 9L: POA 2 Inflow Area = 474.610 ac, 9.58% Impervious, Inflow Depth = 0.47" for 1-YR event Inflow = 72.40 cfs @ 12.60 hrs, Volume= 18.658 af Primary = 72.40 cfs @ 12.60 hrs, Volume= 18.658 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Summary for Subcatchment 10S: ONSITE SHEETFLOW Runoff = 0.18 cfs @ 12.08 hrs, Volume= 0.020 af, Depth= 0.29" 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=3.04" 24 PREDEV TOTAL Type II 24-hr 1-YR Rainfall=3.04"PREDEV TOTAL Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 6HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Area (ac) CN Description 0.830 58 Woods/grass comb., Good, HSG B 0.830 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 11.2 Direct Entry, Summary for Link 11L: POA 3 (COW BRANCH) Inflow Area = 475.440 ac, 9.57% Impervious, Inflow Depth = 0.47" for 1-YR event Inflow = 72.45 cfs @ 12.60 hrs, Volume= 18.678 af Primary = 72.45 cfs @ 12.60 hrs, Volume= 18.678 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs 25 PREDEV TOTAL Type II 24-hr 10-YR Rainfall=5.55"PREDEV TOTAL Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 7HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC 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 Runoff Area=0.630 ac 4.76% Impervious Runoff Depth=2.28"Subcatchment 1S: ONSITE TO POA 1 Tc=11.6 min CN=68 Runoff=2.06 cfs 0.120 af Runoff Area=89.910 ac 30.00% Impervious Runoff Depth=2.63"Subcatchment 2S: OFFSITE TO POA 1 Tc=67.3 min CN=72 Runoff=113.98 cfs 19.701 af Runoff Area=157.690 ac 0.00% Impervious Runoff Depth=1.48"Subcatchment 3S: OFFSITE TO POA 1 Tc=67.6 min CN=58 Runoff=98.75 cfs 19.491 af Inflow=212.33 cfs 39.312 afLink 4L: POA 1 Primary=212.33 cfs 39.312 af Runoff Area=11.900 ac 4.79% Impervious Runoff Depth=2.45"Subcatchment 5S: ONSITE TO POA 2 Tc=18.7 min CN=70 Runoff=33.24 cfs 2.432 af Runoff Area=59.700 ac 30.00% Impervious Runoff Depth=2.63"Subcatchment 6S: OFFSITE TO POA 2 Tc=29.0 min CN=72 Runoff=137.44 cfs 13.082 af Runoff Area=20.840 ac 0.00% Impervious Runoff Depth=1.56"Subcatchment 7S: OFFSITE TO POA 2 Tc=23.5 min CN=59 Runoff=29.68 cfs 2.706 af Runoff Area=133.940 ac 0.00% Impervious Runoff Depth=1.48"Subcatchment 8S: OFFSITE TO POA 2 Tc=45.5 min CN=58 Runoff=112.40 cfs 16.555 af Inflow=385.89 cfs 74.086 afLink 9L: POA 2 Primary=385.89 cfs 74.086 af Runoff Area=0.830 ac 0.00% Impervious Runoff Depth=1.48"Subcatchment 10S: ONSITE SHEETFLOW Tc=11.2 min CN=58 Runoff=1.69 cfs 0.103 af Inflow=386.16 cfs 74.189 afLink 11L: POA 3 (COW BRANCH) Primary=386.16 cfs 74.189 af Total Runoff Area = 475.440 ac Runoff Volume = 74.189 af Average Runoff Depth = 1.87" 90.43% Pervious = 429.957 ac 9.57% Impervious = 45.483 ac 26 PREDEV TOTAL Type II 24-hr 10-YR Rainfall=5.55"PREDEV TOTAL Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 8HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: ONSITE TO POA 1 Runoff = 2.06 cfs @ 12.04 hrs, Volume= 0.120 af, Depth= 2.28" 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=5.55" Area (ac) CN Description 0.380 73 Small grain, contoured, Good, HSG B 0.220 55 Woods, Good, HSG B * 0.030 98 Impervious 0.630 68 Weighted Average 0.600 95.24% Pervious Area 0.030 4.76% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 11.6 Direct Entry, Summary for Subcatchment 2S: OFFSITE TO POA 1 (NORTH OF RTE 20, TOC V) Runoff = 113.98 cfs @ 12.74 hrs, Volume= 19.701 af, Depth= 2.63" 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=5.55" Area (ac) CN Description 89.910 72 1/3 acre lots, 30% imp, HSG B 62.937 70.00% Pervious Area 26.973 30.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 67.3 Direct Entry, Summary for Subcatchment 3S: OFFSITE TO POA 1 (SOUTH OF RTE 20, TOC VI) Runoff = 98.75 cfs @ 12.82 hrs, Volume= 19.491 af, Depth= 1.48" 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=5.55" Area (ac) CN Description 157.690 58 Woods/grass comb., Good, HSG B 157.690 100.00% Pervious Area 27 PREDEV TOTAL Type II 24-hr 10-YR Rainfall=5.55"PREDEV TOTAL Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 9HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 67.6 Direct Entry, Summary for Link 4L: POA 1 Inflow Area = 248.230 ac, 10.88% Impervious, Inflow Depth = 1.90" for 10-YR event Inflow = 212.33 cfs @ 12.77 hrs, Volume= 39.312 af Primary = 212.33 cfs @ 12.77 hrs, Volume= 39.312 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Summary for Subcatchment 5S: ONSITE TO POA 2 Runoff = 33.24 cfs @ 12.12 hrs, Volume= 2.432 af, Depth= 2.45" 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=5.55" Area (ac) CN Description 8.350 73 Small grain, contoured, Good, HSG B 2.980 55 Woods, Good, HSG B * 0.570 98 Impervious 11.900 70 Weighted Average 11.330 95.21% Pervious Area 0.570 4.79% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 18.7 Direct Entry, Summary for Subcatchment 6S: OFFSITE TO POA 2 (NORTH OF SITE, TOC III) Runoff = 137.44 cfs @ 12.24 hrs, Volume= 13.082 af, Depth= 2.63" 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=5.55" Area (ac) CN Description 59.700 72 1/3 acre lots, 30% imp, HSG B 41.790 70.00% Pervious Area 17.910 30.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 29.0 Direct Entry, 28 PREDEV TOTAL Type II 24-hr 10-YR Rainfall=5.55"PREDEV TOTAL Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 10HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Subcatchment 7S: OFFSITE TO POA 2 (NORTHEAST OF SITE, TOC I) Runoff = 29.68 cfs @ 12.19 hrs, Volume= 2.706 af, Depth= 1.56" 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=5.55" Area (ac) CN Description * 20.840 59 Woods/grass combo 2, Good, HSG B 20.840 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 23.5 Direct Entry, Summary for Subcatchment 8S: OFFSITE TO POA 2 (SOUTH OF SITE, TOC VII) Runoff = 112.40 cfs @ 12.49 hrs, Volume= 16.555 af, Depth= 1.48" 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=5.55" Area (ac) CN Description 133.940 58 Woods/grass comb., Good, HSG B 133.940 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 45.5 Direct Entry, Summary for Link 9L: POA 2 Inflow Area = 474.610 ac, 9.58% Impervious, Inflow Depth = 1.87" for 10-YR event Inflow = 385.89 cfs @ 12.49 hrs, Volume= 74.086 af Primary = 385.89 cfs @ 12.49 hrs, Volume= 74.086 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Summary for Subcatchment 10S: ONSITE SHEETFLOW Runoff = 1.69 cfs @ 12.04 hrs, Volume= 0.103 af, Depth= 1.48" 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=5.55" 29 PREDEV TOTAL Type II 24-hr 10-YR Rainfall=5.55"PREDEV TOTAL Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 11HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Area (ac) CN Description 0.830 58 Woods/grass comb., Good, HSG B 0.830 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 11.2 Direct Entry, Summary for Link 11L: POA 3 (COW BRANCH) Inflow Area = 475.440 ac, 9.57% Impervious, Inflow Depth = 1.87" for 10-YR event Inflow = 386.16 cfs @ 12.49 hrs, Volume= 74.189 af Primary = 386.16 cfs @ 12.49 hrs, Volume= 74.189 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs 30 PREDEV TOTAL Type II 24-hr 100-YR Rainfall=9.13"PREDEV TOTAL Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 12HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC 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 Runoff Area=0.630 ac 4.76% Impervious Runoff Depth=5.20"Subcatchment 1S: ONSITE TO POA 1 Tc=11.6 min CN=68 Runoff=4.69 cfs 0.273 af Runoff Area=89.910 ac 30.00% Impervious Runoff Depth=5.70"Subcatchment 2S: OFFSITE TO POA 1 Tc=67.3 min CN=72 Runoff=251.76 cfs 42.698 af Runoff Area=157.690 ac 0.00% Impervious Runoff Depth=3.95"Subcatchment 3S: OFFSITE TO POA 1 Tc=67.6 min CN=58 Runoff=295.56 cfs 51.961 af Inflow=547.87 cfs 94.933 afLink 4L: POA 1 Primary=547.87 cfs 94.933 af Runoff Area=11.900 ac 4.79% Impervious Runoff Depth=5.45"Subcatchment 5S: ONSITE TO POA 2 Tc=18.7 min CN=70 Runoff=74.45 cfs 5.404 af Runoff Area=59.700 ac 30.00% Impervious Runoff Depth=5.70"Subcatchment 6S: OFFSITE TO POA 2 Tc=29.0 min CN=72 Runoff=300.83 cfs 28.352 af Runoff Area=20.840 ac 0.00% Impervious Runoff Depth=4.08"Subcatchment 7S: OFFSITE TO POA 2 Tc=23.5 min CN=59 Runoff=84.66 cfs 7.083 af Runoff Area=133.940 ac 0.00% Impervious Runoff Depth=3.95"Subcatchment 8S: OFFSITE TO POA 2 Tc=45.5 min CN=58 Runoff=335.67 cfs 44.135 af Inflow=1,020.59 cfs 179.907 afLink 9L: POA 2 Primary=1,020.59 cfs 179.907 af Runoff Area=0.830 ac 0.00% Impervious Runoff Depth=3.95"Subcatchment 10S: ONSITE SHEETFLOW Tc=11.2 min CN=58 Runoff=4.77 cfs 0.273 af Inflow=1,021.29 cfs 180.180 afLink 11L: POA 3 (COW BRANCH) Primary=1,021.29 cfs 180.180 af Total Runoff Area = 475.440 ac Runoff Volume = 180.180 af Average Runoff Depth = 4.55" 90.43% Pervious = 429.957 ac 9.57% Impervious = 45.483 ac 31 PREDEV TOTAL Type II 24-hr 100-YR Rainfall=9.13"PREDEV TOTAL Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 13HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: ONSITE TO POA 1 Runoff = 4.69 cfs @ 12.03 hrs, Volume= 0.273 af, Depth= 5.20" 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=9.13" Area (ac) CN Description 0.380 73 Small grain, contoured, Good, HSG B 0.220 55 Woods, Good, HSG B * 0.030 98 Impervious 0.630 68 Weighted Average 0.600 95.24% Pervious Area 0.030 4.76% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 11.6 Direct Entry, Summary for Subcatchment 2S: OFFSITE TO POA 1 (NORTH OF RTE 20, TOC V) Runoff = 251.76 cfs @ 12.71 hrs, Volume= 42.698 af, Depth= 5.70" 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=9.13" Area (ac) CN Description 89.910 72 1/3 acre lots, 30% imp, HSG B 62.937 70.00% Pervious Area 26.973 30.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 67.3 Direct Entry, Summary for Subcatchment 3S: OFFSITE TO POA 1 (SOUTH OF RTE 20, TOC VI) Runoff = 295.56 cfs @ 12.74 hrs, Volume= 51.961 af, Depth= 3.95" 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=9.13" Area (ac) CN Description 157.690 58 Woods/grass comb., Good, HSG B 157.690 100.00% Pervious Area 32 PREDEV TOTAL Type II 24-hr 100-YR Rainfall=9.13"PREDEV TOTAL Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 14HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 67.6 Direct Entry, Summary for Link 4L: POA 1 Inflow Area = 248.230 ac, 10.88% Impervious, Inflow Depth = 4.59" for 100-YR event Inflow = 547.87 cfs @ 12.72 hrs, Volume= 94.933 af Primary = 547.87 cfs @ 12.72 hrs, Volume= 94.933 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Summary for Subcatchment 5S: ONSITE TO POA 2 Runoff = 74.45 cfs @ 12.11 hrs, Volume= 5.404 af, Depth= 5.45" 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=9.13" Area (ac) CN Description 8.350 73 Small grain, contoured, Good, HSG B 2.980 55 Woods, Good, HSG B * 0.570 98 Impervious 11.900 70 Weighted Average 11.330 95.21% Pervious Area 0.570 4.79% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 18.7 Direct Entry, Summary for Subcatchment 6S: OFFSITE TO POA 2 (NORTH OF SITE, TOC III) Runoff = 300.83 cfs @ 12.23 hrs, Volume= 28.352 af, Depth= 5.70" 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=9.13" Area (ac) CN Description 59.700 72 1/3 acre lots, 30% imp, HSG B 41.790 70.00% Pervious Area 17.910 30.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 29.0 Direct Entry, 33 PREDEV TOTAL Type II 24-hr 100-YR Rainfall=9.13"PREDEV TOTAL Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 15HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Subcatchment 7S: OFFSITE TO POA 2 (NORTHEAST OF SITE, TOC I) Runoff = 84.66 cfs @ 12.17 hrs, Volume= 7.083 af, Depth= 4.08" 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=9.13" Area (ac) CN Description * 20.840 59 Woods/grass combo 2, Good, HSG B 20.840 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 23.5 Direct Entry, Summary for Subcatchment 8S: OFFSITE TO POA 2 (SOUTH OF SITE, TOC VII) Runoff = 335.67 cfs @ 12.45 hrs, Volume= 44.135 af, Depth= 3.95" 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=9.13" Area (ac) CN Description 133.940 58 Woods/grass comb., Good, HSG B 133.940 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 45.5 Direct Entry, Summary for Link 9L: POA 2 Inflow Area = 474.610 ac, 9.58% Impervious, Inflow Depth = 4.55" for 100-YR event Inflow = 1,020.59 cfs @ 12.46 hrs, Volume= 179.907 af Primary = 1,020.59 cfs @ 12.46 hrs, Volume= 179.907 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Summary for Subcatchment 10S: ONSITE SHEETFLOW Runoff = 4.77 cfs @ 12.03 hrs, Volume= 0.273 af, Depth= 3.95" 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=9.13" 34 PREDEV TOTAL Type II 24-hr 100-YR Rainfall=9.13"PREDEV TOTAL Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 16HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Area (ac) CN Description 0.830 58 Woods/grass comb., Good, HSG B 0.830 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 11.2 Direct Entry, Summary for Link 11L: POA 3 (COW BRANCH) Inflow Area = 475.440 ac, 9.57% Impervious, Inflow Depth = 4.55" for 100-YR event Inflow = 1,021.29 cfs @ 12.46 hrs, Volume= 180.180 af Primary = 1,021.29 cfs @ 12.46 hrs, Volume= 180.180 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs 35 1S ONSITE TO POA 1 4L POA 1 5S ONSITE TO POA 2 9L POA 2 10S ONSITE SHEETFLOW 11L POA 3 (COW BRANCH) Drainage Diagram for PREDEV ONSITE FOR EBE Prepared by Shimp Engineering, P.C., Printed 7/2/2020 HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Subcat Reach Pond Link 36 PREDEV ONSITE Type II 24-hr 1-YR Rainfall=3.04"PREDEV ONSITE FOR EBE Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 2HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC 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 Runoff Area=0.630 ac 4.76% Impervious Runoff Depth=0.65"Subcatchment 1S: ONSITE TO POA 1 Tc=11.6 min CN=68 Runoff=0.52 cfs 0.034 af Inflow=0.52 cfs 0.034 afLink 4L: POA 1 Primary=0.52 cfs 0.034 af Runoff Area=11.900 ac 4.79% Impervious Runoff Depth=0.74"Subcatchment 5S: ONSITE TO POA 2 Tc=18.7 min CN=70 Runoff=8.87 cfs 0.730 af Inflow=9.24 cfs 0.764 afLink 9L: POA 2 Primary=9.24 cfs 0.764 af Runoff Area=1.170 ac 0.00% Impervious Runoff Depth=0.29"Subcatchment 10S: ONSITE SHEETFLOW Tc=11.2 min CN=58 Runoff=0.25 cfs 0.028 af Inflow=9.46 cfs 0.792 afLink 11L: POA 3 (COW BRANCH) Primary=9.46 cfs 0.792 af Total Runoff Area = 13.700 ac Runoff Volume = 0.792 af Average Runoff Depth = 0.69" 95.62% Pervious = 13.100 ac 4.38% Impervious = 0.600 ac 37 PREDEV ONSITE Type II 24-hr 1-YR Rainfall=3.04"PREDEV ONSITE FOR EBE Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 3HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: ONSITE TO POA 1 Runoff = 0.52 cfs @ 12.05 hrs, Volume= 0.034 af, Depth= 0.65" 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=3.04" Area (ac) CN Description 0.380 73 Small grain, contoured, Good, HSG B 0.220 55 Woods, Good, HSG B * 0.030 98 Impervious 0.630 68 Weighted Average 0.600 95.24% Pervious Area 0.030 4.76% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 11.6 Direct Entry, Summary for Link 4L: POA 1 Inflow Area = 0.630 ac, 4.76% Impervious, Inflow Depth = 0.65" for 1-YR event Inflow = 0.52 cfs @ 12.05 hrs, Volume= 0.034 af Primary = 0.52 cfs @ 12.05 hrs, Volume= 0.034 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Summary for Subcatchment 5S: ONSITE TO POA 2 Runoff = 8.87 cfs @ 12.14 hrs, Volume= 0.730 af, Depth= 0.74" 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=3.04" Area (ac) CN Description 8.350 73 Small grain, contoured, Good, HSG B 2.980 55 Woods, Good, HSG B * 0.570 98 Impervious 11.900 70 Weighted Average 11.330 95.21% Pervious Area 0.570 4.79% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 18.7 Direct Entry, 38 PREDEV ONSITE Type II 24-hr 1-YR Rainfall=3.04"PREDEV ONSITE FOR EBE Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 4HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Link 9L: POA 2 Inflow Area = 12.530 ac, 4.79% Impervious, Inflow Depth = 0.73" for 1-YR event Inflow = 9.24 cfs @ 12.13 hrs, Volume= 0.764 af Primary = 9.24 cfs @ 12.13 hrs, Volume= 0.764 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Summary for Subcatchment 10S: ONSITE SHEETFLOW Runoff = 0.25 cfs @ 12.08 hrs, Volume= 0.028 af, Depth= 0.29" 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=3.04" Area (ac) CN Description 1.170 58 Woods/grass comb., Good, HSG B 1.170 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 11.2 Direct Entry, Summary for Link 11L: POA 3 (COW BRANCH) Inflow Area = 13.700 ac, 4.38% Impervious, Inflow Depth = 0.69" for 1-YR event Inflow = 9.46 cfs @ 12.13 hrs, Volume= 0.792 af Primary = 9.46 cfs @ 12.13 hrs, Volume= 0.792 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs 39 PREDEV ONSITE Type II 24-hr 10-YR Rainfall=5.55"PREDEV ONSITE FOR EBE Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 5HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC 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 Runoff Area=0.630 ac 4.76% Impervious Runoff Depth=2.28"Subcatchment 1S: ONSITE TO POA 1 Tc=11.6 min CN=68 Runoff=2.06 cfs 0.120 af Inflow=2.06 cfs 0.120 afLink 4L: POA 1 Primary=2.06 cfs 0.120 af Runoff Area=11.900 ac 4.79% Impervious Runoff Depth=2.45"Subcatchment 5S: ONSITE TO POA 2 Tc=18.7 min CN=70 Runoff=33.24 cfs 2.432 af Inflow=34.83 cfs 2.552 afLink 9L: POA 2 Primary=34.83 cfs 2.552 af Runoff Area=1.170 ac 0.00% Impervious Runoff Depth=1.48"Subcatchment 10S: ONSITE SHEETFLOW Tc=11.2 min CN=58 Runoff=2.38 cfs 0.145 af Inflow=36.73 cfs 2.697 afLink 11L: POA 3 (COW BRANCH) Primary=36.73 cfs 2.697 af Total Runoff Area = 13.700 ac Runoff Volume = 2.697 af Average Runoff Depth = 2.36" 95.62% Pervious = 13.100 ac 4.38% Impervious = 0.600 ac 40 PREDEV ONSITE Type II 24-hr 10-YR Rainfall=5.55"PREDEV ONSITE FOR EBE Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 6HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: ONSITE TO POA 1 Runoff = 2.06 cfs @ 12.04 hrs, Volume= 0.120 af, Depth= 2.28" 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=5.55" Area (ac) CN Description 0.380 73 Small grain, contoured, Good, HSG B 0.220 55 Woods, Good, HSG B * 0.030 98 Impervious 0.630 68 Weighted Average 0.600 95.24% Pervious Area 0.030 4.76% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 11.6 Direct Entry, Summary for Link 4L: POA 1 Inflow Area = 0.630 ac, 4.76% Impervious, Inflow Depth = 2.28" for 10-YR event Inflow = 2.06 cfs @ 12.04 hrs, Volume= 0.120 af Primary = 2.06 cfs @ 12.04 hrs, Volume= 0.120 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Summary for Subcatchment 5S: ONSITE TO POA 2 Runoff = 33.24 cfs @ 12.12 hrs, Volume= 2.432 af, Depth= 2.45" 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=5.55" Area (ac) CN Description 8.350 73 Small grain, contoured, Good, HSG B 2.980 55 Woods, Good, HSG B * 0.570 98 Impervious 11.900 70 Weighted Average 11.330 95.21% Pervious Area 0.570 4.79% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 18.7 Direct Entry, 41 PREDEV ONSITE Type II 24-hr 10-YR Rainfall=5.55"PREDEV ONSITE FOR EBE Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 7HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Link 9L: POA 2 Inflow Area = 12.530 ac, 4.79% Impervious, Inflow Depth = 2.44" for 10-YR event Inflow = 34.83 cfs @ 12.11 hrs, Volume= 2.552 af Primary = 34.83 cfs @ 12.11 hrs, Volume= 2.552 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Summary for Subcatchment 10S: ONSITE SHEETFLOW Runoff = 2.38 cfs @ 12.04 hrs, Volume= 0.145 af, Depth= 1.48" 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=5.55" Area (ac) CN Description 1.170 58 Woods/grass comb., Good, HSG B 1.170 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 11.2 Direct Entry, Summary for Link 11L: POA 3 (COW BRANCH) Inflow Area = 13.700 ac, 4.38% Impervious, Inflow Depth = 2.36" for 10-YR event Inflow = 36.73 cfs @ 12.11 hrs, Volume= 2.697 af Primary = 36.73 cfs @ 12.11 hrs, Volume= 2.697 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs 42 PREDEV ONSITE Type II 24-hr 100-YR Rainfall=9.13"PREDEV ONSITE FOR EBE Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 8HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC 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 Runoff Area=0.630 ac 4.76% Impervious Runoff Depth=5.20"Subcatchment 1S: ONSITE TO POA 1 Tc=11.6 min CN=68 Runoff=4.69 cfs 0.273 af Inflow=4.69 cfs 0.273 afLink 4L: POA 1 Primary=4.69 cfs 0.273 af Runoff Area=11.900 ac 4.79% Impervious Runoff Depth=5.45"Subcatchment 5S: ONSITE TO POA 2 Tc=18.7 min CN=70 Runoff=74.45 cfs 5.404 af Inflow=78.11 cfs 5.677 afLink 9L: POA 2 Primary=78.11 cfs 5.677 af Runoff Area=1.170 ac 0.00% Impervious Runoff Depth=3.95"Subcatchment 10S: ONSITE SHEETFLOW Tc=11.2 min CN=58 Runoff=6.72 cfs 0.386 af Inflow=83.47 cfs 6.063 afLink 11L: POA 3 (COW BRANCH) Primary=83.47 cfs 6.063 af Total Runoff Area = 13.700 ac Runoff Volume = 6.063 af Average Runoff Depth = 5.31" 95.62% Pervious = 13.100 ac 4.38% Impervious = 0.600 ac 43 PREDEV ONSITE Type II 24-hr 100-YR Rainfall=9.13"PREDEV ONSITE FOR EBE Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 9HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: ONSITE TO POA 1 Runoff = 4.69 cfs @ 12.03 hrs, Volume= 0.273 af, Depth= 5.20" 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=9.13" Area (ac) CN Description 0.380 73 Small grain, contoured, Good, HSG B 0.220 55 Woods, Good, HSG B * 0.030 98 Impervious 0.630 68 Weighted Average 0.600 95.24% Pervious Area 0.030 4.76% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 11.6 Direct Entry, Summary for Link 4L: POA 1 Inflow Area = 0.630 ac, 4.76% Impervious, Inflow Depth = 5.20" for 100-YR event Inflow = 4.69 cfs @ 12.03 hrs, Volume= 0.273 af Primary = 4.69 cfs @ 12.03 hrs, Volume= 0.273 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Summary for Subcatchment 5S: ONSITE TO POA 2 Runoff = 74.45 cfs @ 12.11 hrs, Volume= 5.404 af, Depth= 5.45" 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=9.13" Area (ac) CN Description 8.350 73 Small grain, contoured, Good, HSG B 2.980 55 Woods, Good, HSG B * 0.570 98 Impervious 11.900 70 Weighted Average 11.330 95.21% Pervious Area 0.570 4.79% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 18.7 Direct Entry, 44 PREDEV ONSITE Type II 24-hr 100-YR Rainfall=9.13"PREDEV ONSITE FOR EBE Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 10HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Link 9L: POA 2 Inflow Area = 12.530 ac, 4.79% Impervious, Inflow Depth = 5.44" for 100-YR event Inflow = 78.11 cfs @ 12.11 hrs, Volume= 5.677 af Primary = 78.11 cfs @ 12.11 hrs, Volume= 5.677 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Summary for Subcatchment 10S: ONSITE SHEETFLOW Runoff = 6.72 cfs @ 12.03 hrs, Volume= 0.386 af, Depth= 3.95" 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=9.13" Area (ac) CN Description 1.170 58 Woods/grass comb., Good, HSG B 1.170 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 11.2 Direct Entry, Summary for Link 11L: POA 3 (COW BRANCH) Inflow Area = 13.700 ac, 4.38% Impervious, Inflow Depth = 5.31" for 100-YR event Inflow = 83.47 cfs @ 12.10 hrs, Volume= 6.063 af Primary = 83.47 cfs @ 12.10 hrs, Volume= 6.063 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs 45 1S ONSITE TO BMP 1 VIA F3&F4 2S OFFSITE TO BMP 1 VIA F2 (TOC I) 3P BMP 1 4S ONSITE TO POA 1 5S OFFSITE TO POA 1 VIA E9 (TOC II) 6S OFFSITE TO POA 1 VIA E7C (TOC III) 7S OFFSITE TO POA 1 VIA DITCH 1 (TOC IV) 8S OFFSITE TO POA 1 VIA G2 (TOC V) 9S OFFSITE TO POA 1 VIA G2 (TOC VI) 10L POA 1 11S ONSITE TO POA 2 12S OFFSITE TO POA 2 VIA A2 (TOC VII) 13L POA 2 14S ONSITE TO POA 3 15L POA 3 (COW BRANCH) Drainage Diagram for POSTDEV TOTAL Prepared by Shimp Engineering, P.C., Printed 7/2/2020 HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Subcat Reach Pond Link 46 POSTDEV TOTAL Type II 24-hr 1-YR Rainfall=3.04"POSTDEV TOTAL Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 2HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC 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 Runoff Area=1.130 ac 55.75% Impervious Runoff Depth=1.41"Subcatchment 1S: ONSITE TO BMP 1 VIA Tc=5.0 min CN=82 Runoff=2.87 cfs 0.133 af Runoff Area=26.720 ac 8.31% Impervious Runoff Depth=0.35"Subcatchment 2S: OFFSITE TO BMP 1 VIA Tc=23.2 min CN=60 Runoff=5.26 cfs 0.775 af Peak Elev=478.23' Storage=0.340 af Inflow=5.64 cfs 0.907 afPond 3P: BMP 1 Outflow=1.33 cfs 0.616 af Runoff Area=7.380 ac 47.56% Impervious Runoff Depth=1.16"Subcatchment 4S: ONSITE TO POA 1 Tc=5.0 min CN=78 Runoff=15.35 cfs 0.712 af Runoff Area=12.610 ac 30.00% Impervious Runoff Depth=0.83"Subcatchment 5S: OFFSITE TO POA 1 VIA Tc=23.2 min CN=72 Runoff=9.60 cfs 0.874 af Runoff Area=38.520 ac 30.00% Impervious Runoff Depth=0.83"Subcatchment 6S: OFFSITE TO POA 1 VIA Tc=29.0 min CN=72 Runoff=25.26 cfs 2.671 af Runoff Area=2.840 ac 25.00% Impervious Runoff Depth=0.74"Subcatchment 7S: OFFSITE TO POA 1 VIA Tc=16.5 min CN=70 Runoff=2.29 cfs 0.174 af Runoff Area=89.860 ac 30.00% Impervious Runoff Depth=0.83"Subcatchment 8S: OFFSITE TO POA 1 VIA Tc=67.3 min CN=72 Runoff=31.98 cfs 6.230 af Runoff Area=157.700 ac 0.00% Impervious Runoff Depth=0.29"Subcatchment 9S: OFFSITE TO POA 1 VIA Tc=67.6 min CN=58 Runoff=11.42 cfs 3.769 af Inflow=54.73 cfs 15.047 afLink 10L: POA 1 Primary=54.73 cfs 15.047 af Runoff Area=4.220 ac 28.91% Impervious Runoff Depth=0.74"Subcatchment 11S: ONSITE TO POA 2 Tc=5.0 min CN=70 Runoff=5.31 cfs 0.259 af Runoff Area=133.490 ac 0.00% Impervious Runoff Depth=0.29"Subcatchment 12S: OFFSITE TO POA 2 Tc=45.5 min CN=58 Runoff=12.03 cfs 3.191 af Inflow=67.19 cfs 18.496 afLink 13L: POA 2 Primary=67.19 cfs 18.496 af Runoff Area=0.970 ac 0.00% Impervious Runoff Depth=0.29"Subcatchment 14S: ONSITE TO POA 3 Tc=5.0 min CN=58 Runoff=0.31 cfs 0.023 af Inflow=67.24 cfs 18.520 afLink 15L: POA 3 (COW BRANCH) Primary=67.24 cfs 18.520 af Total Runoff Area = 475.440 ac Runoff Volume = 18.811 af Average Runoff Depth = 0.47" 89.36% Pervious = 424.853 ac 10.64% Impervious = 50.587 ac 47 POSTDEV TOTAL Type II 24-hr 1-YR Rainfall=3.04"POSTDEV TOTAL Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 3HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: ONSITE TO BMP 1 VIA F3&F4 Runoff = 2.87 cfs @ 11.96 hrs, Volume= 0.133 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 1-YR Rainfall=3.04" Area (ac) CN Description 0.500 61 >75% Grass cover, Good, HSG B * 0.630 98 Impervious 1.130 82 Weighted Average 0.500 44.25% Pervious Area 0.630 55.75% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 2S: OFFSITE TO BMP 1 VIA F2 (TOC I) Runoff = 5.26 cfs @ 12.24 hrs, Volume= 0.775 af, Depth= 0.35" 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=3.04" Area (ac) CN Description 19.700 55 Woods, Good, HSG B * 2.220 98 Impervious 4.800 61 >75% Grass cover, Good, HSG B 26.720 60 Weighted Average 24.500 91.69% Pervious Area 2.220 8.31% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 23.2 Direct Entry, Summary for Pond 3P: BMP 1 Inflow Area = 27.850 ac, 10.23% Impervious, Inflow Depth = 0.39" for 1-YR event Inflow = 5.64 cfs @ 12.24 hrs, Volume= 0.907 af Outflow = 1.33 cfs @ 13.46 hrs, Volume= 0.616 af, Atten= 76%, Lag= 73.3 min Primary = 1.33 cfs @ 13.46 hrs, Volume= 0.616 af Routing by Stor-Ind method, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Peak Elev= 478.23' @ 13.46 hrs Surf.Area= 0.198 ac Storage= 0.340 af Plug-Flow detention time= 255.8 min calculated for 0.616 af (68% of inflow) Center-of-Mass det. time= 125.7 min ( 1,052.9 - 927.3 ) 48 POSTDEV TOTAL Type II 24-hr 1-YR Rainfall=3.04"POSTDEV TOTAL Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 4HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Volume Invert Avail.Storage Storage Description #1 475.00' 0.440 af 9.08'W x 5.66'L x 7.60'H STONE STORAGE x 168 1.506 af Overall - 0.406 af Embedded = 1.100 af x 40.0% Voids #2 477.00' 0.391 af StormTech MC-4500 x 160 Inside #1 Effective Size= 90.4"W x 60.0"H => 26.46 sf x 4.03'L = 106.5 cf Overall Size= 100.0"W x 60.0"H x 4.33'L with 0.31' Overlap #3 477.00' 0.015 af StormTech MC-4500 Cap x 18 Inside #1 Effective Size= 63.5"W x 59.0"H => 15.25 sf x 2.34'L = 35.7 cf Overall Size= 90.2"W x 59.4"H x 2.92'L with 0.58' Overlap 0.846 af Total Available Storage Device Routing Invert Outlet Devices #1 Primary 476.00'36.0" Round Culvert L= 16.1' Ke= 0.500 Inlet / Outlet Invert= 476.00' / 475.20' S= 0.0497 '/' Cc= 0.900 n= 0.012 #2 Device 1 477.90'26.0" W x 13.0" H Vert. Orifice/Grate C= 0.600 #3 Device 1 480.82'5.0' long x 6.00' rise Sharp-Crested Rectangular Weir 2 End Contraction(s) 4.0' Crest Height #4 Primary 482.75'36.0" Horiz. Orifice/Grate C= 0.600 in 36.0" x 36.0" Grate Limited to weir flow at low heads Primary OutFlow Max=1.33 cfs @ 13.46 hrs HW=478.23' (Free Discharge) 1=Culvert (Passes 1.33 cfs of 28.68 cfs potential flow) 2=Orifice/Grate (Orifice Controls 1.33 cfs @ 1.85 fps) 3=Sharp-Crested Rectangular Weir ( Controls 0.00 cfs) 4=Orifice/Grate ( Controls 0.00 cfs) Summary for Subcatchment 4S: ONSITE TO POA 1 Runoff = 15.35 cfs @ 11.96 hrs, Volume= 0.712 af, Depth= 1.16" 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=3.04" Area (ac) CN Description * 3.510 98 Impervious 3.570 61 >75% Grass cover, Good, HSG B 0.300 55 Woods, Good, HSG B 7.380 78 Weighted Average 3.870 52.44% Pervious Area 3.510 47.56% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, 49 POSTDEV TOTAL Type II 24-hr 1-YR Rainfall=3.04"POSTDEV TOTAL Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 5HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Subcatchment 5S: OFFSITE TO POA 1 VIA E9 (TOC II) Runoff = 9.60 cfs @ 12.19 hrs, Volume= 0.874 af, Depth= 0.83" 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=3.04" Area (ac) CN Description 12.610 72 1/3 acre lots, 30% imp, HSG B 8.827 70.00% Pervious Area 3.783 30.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 23.2 Direct Entry, Summary for Subcatchment 6S: OFFSITE TO POA 1 VIA E7C (TOC III) Runoff = 25.26 cfs @ 12.26 hrs, Volume= 2.671 af, Depth= 0.83" 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=3.04" Area (ac) CN Description 38.520 72 1/3 acre lots, 30% imp, HSG B 26.964 70.00% Pervious Area 11.556 30.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 29.0 Direct Entry, Summary for Subcatchment 7S: OFFSITE TO POA 1 VIA DITCH 1 (TOC IV) Runoff = 2.29 cfs @ 12.11 hrs, Volume= 0.174 af, Depth= 0.74" 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=3.04" Area (ac) CN Description 2.840 70 1/2 acre lots, 25% imp, HSG B 2.130 75.00% Pervious Area 0.710 25.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 16.5 Direct Entry, 50 POSTDEV TOTAL Type II 24-hr 1-YR Rainfall=3.04"POSTDEV TOTAL Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 6HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Subcatchment 8S: OFFSITE TO POA 1 VIA G2 (TOC V) Runoff = 31.98 cfs @ 12.79 hrs, Volume= 6.230 af, Depth= 0.83" 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=3.04" Area (ac) CN Description 89.860 72 1/3 acre lots, 30% imp, HSG B 62.902 70.00% Pervious Area 26.958 30.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 67.3 Direct Entry, Summary for Subcatchment 9S: OFFSITE TO POA 1 VIA G2 (TOC VI) Runoff = 11.42 cfs @ 13.01 hrs, Volume= 3.769 af, Depth= 0.29" 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=3.04" Area (ac) CN Description 157.700 58 Woods/grass comb., Good, HSG B 157.700 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 67.6 Direct Entry, Summary for Link 10L: POA 1 Inflow Area = 336.760 ac, 14.66% Impervious, Inflow Depth = 0.54" for 1-YR event Inflow = 54.73 cfs @ 12.68 hrs, Volume= 15.047 af Primary = 54.73 cfs @ 12.68 hrs, Volume= 15.047 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Summary for Subcatchment 11S: ONSITE TO POA 2 Runoff = 5.31 cfs @ 11.97 hrs, Volume= 0.259 af, Depth= 0.74" 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=3.04" 51 POSTDEV TOTAL Type II 24-hr 1-YR Rainfall=3.04"POSTDEV TOTAL Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 7HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Area (ac) CN Description 1.500 61 >75% Grass cover, Good, HSG B * 1.220 98 Impervious 1.500 55 Woods, Good, HSG B 4.220 70 Weighted Average 3.000 71.09% Pervious Area 1.220 28.91% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 12S: OFFSITE TO POA 2 VIA A2 (TOC VII) Runoff = 12.03 cfs @ 12.63 hrs, Volume= 3.191 af, Depth= 0.29" 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=3.04" Area (ac) CN Description 133.490 58 Woods/grass comb., Good, HSG B 133.490 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 45.5 Direct Entry, Summary for Link 13L: POA 2 Inflow Area = 474.470 ac, 10.66% Impervious, Inflow Depth = 0.47" for 1-YR event Inflow = 67.19 cfs @ 12.66 hrs, Volume= 18.496 af Primary = 67.19 cfs @ 12.66 hrs, Volume= 18.496 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Summary for Subcatchment 14S: ONSITE TO POA 3 Runoff = 0.31 cfs @ 12.00 hrs, Volume= 0.023 af, Depth= 0.29" 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=3.04" Area (ac) CN Description 0.500 55 Woods, Good, HSG B 0.470 61 >75% Grass cover, Good, HSG B 0.970 58 Weighted Average 0.970 100.00% Pervious Area 52 POSTDEV TOTAL Type II 24-hr 1-YR Rainfall=3.04"POSTDEV TOTAL Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 8HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Link 15L: POA 3 (COW BRANCH) Inflow Area = 475.440 ac, 10.64% Impervious, Inflow Depth = 0.47" for 1-YR event Inflow = 67.24 cfs @ 12.66 hrs, Volume= 18.520 af Primary = 67.24 cfs @ 12.66 hrs, Volume= 18.520 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs 53 POSTDEV TOTAL Type II 24-hr 10-YR Rainfall=5.55"POSTDEV TOTAL Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 9HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC 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 Runoff Area=1.130 ac 55.75% Impervious Runoff Depth=3.58"Subcatchment 1S: ONSITE TO BMP 1 VIA Tc=5.0 min CN=82 Runoff=7.09 cfs 0.337 af Runoff Area=26.720 ac 8.31% Impervious Runoff Depth=1.63"Subcatchment 2S: OFFSITE TO BMP 1 VIA Tc=23.2 min CN=60 Runoff=40.74 cfs 3.638 af Peak Elev=481.77' Storage=0.780 af Inflow=41.73 cfs 3.974 afPond 3P: BMP 1 Outflow=35.72 cfs 3.683 af Runoff Area=7.380 ac 47.56% Impervious Runoff Depth=3.18"Subcatchment 4S: ONSITE TO POA 1 Tc=5.0 min CN=78 Runoff=41.87 cfs 1.958 af Runoff Area=12.610 ac 30.00% Impervious Runoff Depth=2.63"Subcatchment 5S: OFFSITE TO POA 1 VIA Tc=23.2 min CN=72 Runoff=33.46 cfs 2.763 af Runoff Area=38.520 ac 30.00% Impervious Runoff Depth=2.63"Subcatchment 6S: OFFSITE TO POA 1 VIA Tc=29.0 min CN=72 Runoff=88.68 cfs 8.441 af Runoff Area=2.840 ac 25.00% Impervious Runoff Depth=2.45"Subcatchment 7S: OFFSITE TO POA 1 VIA Tc=16.5 min CN=70 Runoff=8.49 cfs 0.581 af Runoff Area=89.860 ac 30.00% Impervious Runoff Depth=2.63"Subcatchment 8S: OFFSITE TO POA 1 VIA Tc=67.3 min CN=72 Runoff=113.92 cfs 19.690 af Runoff Area=157.700 ac 0.00% Impervious Runoff Depth=1.48"Subcatchment 9S: OFFSITE TO POA 1 VIA Tc=67.6 min CN=58 Runoff=98.76 cfs 19.492 af Inflow=268.51 cfs 56.608 afLink 10L: POA 1 Primary=268.51 cfs 56.608 af Runoff Area=4.220 ac 28.91% Impervious Runoff Depth=2.45"Subcatchment 11S: ONSITE TO POA 2 Tc=5.0 min CN=70 Runoff=18.66 cfs 0.863 af Runoff Area=133.490 ac 0.00% Impervious Runoff Depth=1.48"Subcatchment 12S: OFFSITE TO POA 2 Tc=45.5 min CN=58 Runoff=112.02 cfs 16.499 af Inflow=377.20 cfs 73.970 afLink 13L: POA 2 Primary=377.20 cfs 73.970 af Runoff Area=0.970 ac 0.00% Impervious Runoff Depth=1.48"Subcatchment 14S: ONSITE TO POA 3 Tc=5.0 min CN=58 Runoff=2.50 cfs 0.120 af Inflow=377.44 cfs 74.090 afLink 15L: POA 3 (COW BRANCH) Primary=377.44 cfs 74.090 af Total Runoff Area = 475.440 ac Runoff Volume = 74.381 af Average Runoff Depth = 1.88" 89.36% Pervious = 424.853 ac 10.64% Impervious = 50.587 ac 54 POSTDEV TOTAL Type II 24-hr 10-YR Rainfall=5.55"POSTDEV TOTAL Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 10HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: ONSITE TO BMP 1 VIA F3&F4 Runoff = 7.09 cfs @ 11.95 hrs, Volume= 0.337 af, Depth= 3.58" 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=5.55" Area (ac) CN Description 0.500 61 >75% Grass cover, Good, HSG B * 0.630 98 Impervious 1.130 82 Weighted Average 0.500 44.25% Pervious Area 0.630 55.75% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 2S: OFFSITE TO BMP 1 VIA F2 (TOC I) Runoff = 40.74 cfs @ 12.18 hrs, Volume= 3.638 af, Depth= 1.63" 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=5.55" Area (ac) CN Description 19.700 55 Woods, Good, HSG B * 2.220 98 Impervious 4.800 61 >75% Grass cover, Good, HSG B 26.720 60 Weighted Average 24.500 91.69% Pervious Area 2.220 8.31% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 23.2 Direct Entry, Summary for Pond 3P: BMP 1 Inflow Area = 27.850 ac, 10.23% Impervious, Inflow Depth = 1.71" for 10-YR event Inflow = 41.73 cfs @ 12.18 hrs, Volume= 3.974 af Outflow = 35.72 cfs @ 12.29 hrs, Volume= 3.683 af, Atten= 14%, Lag= 6.8 min Primary = 35.72 cfs @ 12.29 hrs, Volume= 3.683 af Routing by Stor-Ind method, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Peak Elev= 481.77' @ 12.29 hrs Surf.Area= 0.198 ac Storage= 0.780 af Plug-Flow detention time= 70.5 min calculated for 3.679 af (93% of inflow) Center-of-Mass det. time= 32.0 min ( 906.5 - 874.5 ) 55 POSTDEV TOTAL Type II 24-hr 10-YR Rainfall=5.55"POSTDEV TOTAL Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 11HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Volume Invert Avail.Storage Storage Description #1 475.00' 0.440 af 9.08'W x 5.66'L x 7.60'H STONE STORAGE x 168 1.506 af Overall - 0.406 af Embedded = 1.100 af x 40.0% Voids #2 477.00' 0.391 af StormTech MC-4500 x 160 Inside #1 Effective Size= 90.4"W x 60.0"H => 26.46 sf x 4.03'L = 106.5 cf Overall Size= 100.0"W x 60.0"H x 4.33'L with 0.31' Overlap #3 477.00' 0.015 af StormTech MC-4500 Cap x 18 Inside #1 Effective Size= 63.5"W x 59.0"H => 15.25 sf x 2.34'L = 35.7 cf Overall Size= 90.2"W x 59.4"H x 2.92'L with 0.58' Overlap 0.846 af Total Available Storage Device Routing Invert Outlet Devices #1 Primary 476.00'36.0" Round Culvert L= 16.1' Ke= 0.500 Inlet / Outlet Invert= 476.00' / 475.20' S= 0.0497 '/' Cc= 0.900 n= 0.012 #2 Device 1 477.90'26.0" W x 13.0" H Vert. Orifice/Grate C= 0.600 #3 Device 1 480.82'5.0' long x 6.00' rise Sharp-Crested Rectangular Weir 2 End Contraction(s) 4.0' Crest Height #4 Primary 482.75'36.0" Horiz. Orifice/Grate C= 0.600 in 36.0" x 36.0" Grate Limited to weir flow at low heads Primary OutFlow Max=35.45 cfs @ 12.29 hrs HW=481.77' (Free Discharge) 1=Culvert (Passes 35.45 cfs of 70.29 cfs potential flow) 2=Orifice/Grate (Orifice Controls 20.58 cfs @ 8.77 fps) 3=Sharp-Crested Rectangular Weir (Weir Controls 14.87 cfs @ 3.27 fps) 4=Orifice/Grate ( Controls 0.00 cfs) Summary for Subcatchment 4S: ONSITE TO POA 1 Runoff = 41.87 cfs @ 11.96 hrs, Volume= 1.958 af, Depth= 3.18" 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=5.55" Area (ac) CN Description * 3.510 98 Impervious 3.570 61 >75% Grass cover, Good, HSG B 0.300 55 Woods, Good, HSG B 7.380 78 Weighted Average 3.870 52.44% Pervious Area 3.510 47.56% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, 56 POSTDEV TOTAL Type II 24-hr 10-YR Rainfall=5.55"POSTDEV TOTAL Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 12HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Subcatchment 5S: OFFSITE TO POA 1 VIA E9 (TOC II) Runoff = 33.46 cfs @ 12.17 hrs, Volume= 2.763 af, Depth= 2.63" 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=5.55" Area (ac) CN Description 12.610 72 1/3 acre lots, 30% imp, HSG B 8.827 70.00% Pervious Area 3.783 30.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 23.2 Direct Entry, Summary for Subcatchment 6S: OFFSITE TO POA 1 VIA E7C (TOC III) Runoff = 88.68 cfs @ 12.24 hrs, Volume= 8.441 af, Depth= 2.63" 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=5.55" Area (ac) CN Description 38.520 72 1/3 acre lots, 30% imp, HSG B 26.964 70.00% Pervious Area 11.556 30.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 29.0 Direct Entry, Summary for Subcatchment 7S: OFFSITE TO POA 1 VIA DITCH 1 (TOC IV) Runoff = 8.49 cfs @ 12.09 hrs, Volume= 0.581 af, Depth= 2.45" 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=5.55" Area (ac) CN Description 2.840 70 1/2 acre lots, 25% imp, HSG B 2.130 75.00% Pervious Area 0.710 25.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 16.5 Direct Entry, 57 POSTDEV TOTAL Type II 24-hr 10-YR Rainfall=5.55"POSTDEV TOTAL Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 13HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Subcatchment 8S: OFFSITE TO POA 1 VIA G2 (TOC V) Runoff = 113.92 cfs @ 12.74 hrs, Volume= 19.690 af, Depth= 2.63" 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=5.55" Area (ac) CN Description 89.860 72 1/3 acre lots, 30% imp, HSG B 62.902 70.00% Pervious Area 26.958 30.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 67.3 Direct Entry, Summary for Subcatchment 9S: OFFSITE TO POA 1 VIA G2 (TOC VI) Runoff = 98.76 cfs @ 12.82 hrs, Volume= 19.492 af, Depth= 1.48" 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=5.55" Area (ac) CN Description 157.700 58 Woods/grass comb., Good, HSG B 157.700 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 67.6 Direct Entry, Summary for Link 10L: POA 1 Inflow Area = 336.760 ac, 14.66% Impervious, Inflow Depth = 2.02" for 10-YR event Inflow = 268.51 cfs @ 12.65 hrs, Volume= 56.608 af Primary = 268.51 cfs @ 12.65 hrs, Volume= 56.608 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Summary for Subcatchment 11S: ONSITE TO POA 2 Runoff = 18.66 cfs @ 11.96 hrs, Volume= 0.863 af, Depth= 2.45" 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=5.55" 58 POSTDEV TOTAL Type II 24-hr 10-YR Rainfall=5.55"POSTDEV TOTAL Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 14HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Area (ac) CN Description 1.500 61 >75% Grass cover, Good, HSG B * 1.220 98 Impervious 1.500 55 Woods, Good, HSG B 4.220 70 Weighted Average 3.000 71.09% Pervious Area 1.220 28.91% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 12S: OFFSITE TO POA 2 VIA A2 (TOC VII) Runoff = 112.02 cfs @ 12.49 hrs, Volume= 16.499 af, Depth= 1.48" 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=5.55" Area (ac) CN Description 133.490 58 Woods/grass comb., Good, HSG B 133.490 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 45.5 Direct Entry, Summary for Link 13L: POA 2 Inflow Area = 474.470 ac, 10.66% Impervious, Inflow Depth = 1.87" for 10-YR event Inflow = 377.20 cfs @ 12.53 hrs, Volume= 73.970 af Primary = 377.20 cfs @ 12.53 hrs, Volume= 73.970 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Summary for Subcatchment 14S: ONSITE TO POA 3 Runoff = 2.50 cfs @ 11.97 hrs, Volume= 0.120 af, Depth= 1.48" 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=5.55" Area (ac) CN Description 0.500 55 Woods, Good, HSG B 0.470 61 >75% Grass cover, Good, HSG B 0.970 58 Weighted Average 0.970 100.00% Pervious Area 59 POSTDEV TOTAL Type II 24-hr 10-YR Rainfall=5.55"POSTDEV TOTAL Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 15HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Link 15L: POA 3 (COW BRANCH) Inflow Area = 475.440 ac, 10.64% Impervious, Inflow Depth = 1.87" for 10-YR event Inflow = 377.44 cfs @ 12.53 hrs, Volume= 74.090 af Primary = 377.44 cfs @ 12.53 hrs, Volume= 74.090 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs 60 POSTDEV TOTAL Type II 24-hr 100-YR Rainfall=9.13"POSTDEV TOTAL Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 16HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC 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 Runoff Area=1.130 ac 55.75% Impervious Runoff Depth>6.93"Subcatchment 1S: ONSITE TO BMP 1 VIA Tc=5.0 min CN=82 Runoff=13.26 cfs 0.653 af Runoff Area=26.720 ac 8.31% Impervious Runoff Depth=4.20"Subcatchment 2S: OFFSITE TO BMP 1 VIA Tc=23.2 min CN=60 Runoff=113.07 cfs 9.358 af Peak Elev=484.14' Storage=0.846 af Inflow=114.90 cfs 10.011 afPond 3P: BMP 1 Outflow=127.87 cfs 9.720 af Runoff Area=7.380 ac 47.56% Impervious Runoff Depth>6.44"Subcatchment 4S: ONSITE TO POA 1 Tc=5.0 min CN=78 Runoff=82.04 cfs 3.963 af Runoff Area=12.610 ac 30.00% Impervious Runoff Depth=5.70"Subcatchment 5S: OFFSITE TO POA 1 VIA Tc=23.2 min CN=72 Runoff=72.93 cfs 5.988 af Runoff Area=38.520 ac 30.00% Impervious Runoff Depth=5.70"Subcatchment 6S: OFFSITE TO POA 1 VIA Tc=29.0 min CN=72 Runoff=194.10 cfs 18.293 af Runoff Area=2.840 ac 25.00% Impervious Runoff Depth=5.45"Subcatchment 7S: OFFSITE TO POA 1 VIA Tc=16.5 min CN=70 Runoff=18.94 cfs 1.290 af Runoff Area=89.860 ac 30.00% Impervious Runoff Depth=5.70"Subcatchment 8S: OFFSITE TO POA 1 VIA Tc=67.3 min CN=72 Runoff=251.62 cfs 42.674 af Runoff Area=157.700 ac 0.00% Impervious Runoff Depth=3.95"Subcatchment 9S: OFFSITE TO POA 1 VIA Tc=67.6 min CN=58 Runoff=295.58 cfs 51.965 af Inflow=666.89 cfs 133.893 afLink 10L: POA 1 Primary=666.89 cfs 133.893 af Runoff Area=4.220 ac 28.91% Impervious Runoff Depth=5.45"Subcatchment 11S: ONSITE TO POA 2 Tc=5.0 min CN=70 Runoff=40.80 cfs 1.916 af Runoff Area=133.490 ac 0.00% Impervious Runoff Depth=3.95"Subcatchment 12S: OFFSITE TO POA 2 Tc=45.5 min CN=58 Runoff=334.55 cfs 43.987 af Inflow=995.31 cfs 179.797 afLink 13L: POA 2 Primary=995.31 cfs 179.797 af Runoff Area=0.970 ac 0.00% Impervious Runoff Depth=3.95"Subcatchment 14S: ONSITE TO POA 3 Tc=5.0 min CN=58 Runoff=6.91 cfs 0.320 af Inflow=995.94 cfs 180.117 afLink 15L: POA 3 (COW BRANCH) Primary=995.94 cfs 180.117 af Total Runoff Area = 475.440 ac Runoff Volume = 180.408 af Average Runoff Depth = 4.55" 89.36% Pervious = 424.853 ac 10.64% Impervious = 50.587 ac 61 POSTDEV TOTAL Type II 24-hr 100-YR Rainfall=9.13"POSTDEV TOTAL Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 17HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: ONSITE TO BMP 1 VIA F3&F4 Runoff = 13.26 cfs @ 11.95 hrs, Volume= 0.653 af, Depth> 6.93" 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=9.13" Area (ac) CN Description 0.500 61 >75% Grass cover, Good, HSG B * 0.630 98 Impervious 1.130 82 Weighted Average 0.500 44.25% Pervious Area 0.630 55.75% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 2S: OFFSITE TO BMP 1 VIA F2 (TOC I) Runoff = 113.07 cfs @ 12.17 hrs, Volume= 9.358 af, Depth= 4.20" 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=9.13" Area (ac) CN Description 19.700 55 Woods, Good, HSG B * 2.220 98 Impervious 4.800 61 >75% Grass cover, Good, HSG B 26.720 60 Weighted Average 24.500 91.69% Pervious Area 2.220 8.31% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 23.2 Direct Entry, Summary for Pond 3P: BMP 1 Inflow Area = 27.850 ac, 10.23% Impervious, Inflow Depth > 4.31" for 100-YR event Inflow = 114.90 cfs @ 12.17 hrs, Volume= 10.011 af Outflow = 127.87 cfs @ 12.15 hrs, Volume= 9.720 af, Atten= 0%, Lag= 0.0 min Primary = 127.87 cfs @ 12.15 hrs, Volume= 9.720 af Routing by Stor-Ind method, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Peak Elev= 484.14' @ 12.15 hrs Surf.Area= 0.198 ac Storage= 0.846 af Plug-Flow detention time= 36.1 min calculated for 9.720 af (97% of inflow) Center-of-Mass det. time= 18.4 min ( 866.4 - 848.0 ) 62 POSTDEV TOTAL Type II 24-hr 100-YR Rainfall=9.13"POSTDEV TOTAL Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 18HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Volume Invert Avail.Storage Storage Description #1 475.00' 0.440 af 9.08'W x 5.66'L x 7.60'H STONE STORAGE x 168 1.506 af Overall - 0.406 af Embedded = 1.100 af x 40.0% Voids #2 477.00' 0.391 af StormTech MC-4500 x 160 Inside #1 Effective Size= 90.4"W x 60.0"H => 26.46 sf x 4.03'L = 106.5 cf Overall Size= 100.0"W x 60.0"H x 4.33'L with 0.31' Overlap #3 477.00' 0.015 af StormTech MC-4500 Cap x 18 Inside #1 Effective Size= 63.5"W x 59.0"H => 15.25 sf x 2.34'L = 35.7 cf Overall Size= 90.2"W x 59.4"H x 2.92'L with 0.58' Overlap 0.846 af Total Available Storage Device Routing Invert Outlet Devices #1 Primary 476.00'36.0" Round Culvert L= 16.1' Ke= 0.500 Inlet / Outlet Invert= 476.00' / 475.20' S= 0.0497 '/' Cc= 0.900 n= 0.012 #2 Device 1 477.90'26.0" W x 13.0" H Vert. Orifice/Grate C= 0.600 #3 Device 1 480.82'5.0' long x 6.00' rise Sharp-Crested Rectangular Weir 2 End Contraction(s) 4.0' Crest Height #4 Primary 482.75'36.0" Horiz. Orifice/Grate C= 0.600 in 36.0" x 36.0" Grate Limited to weir flow at low heads Primary OutFlow Max=126.94 cfs @ 12.15 hrs HW=484.10' (Free Discharge) 1=Culvert (Inlet Controls 87.42 cfs @ 12.37 fps) 2=Orifice/Grate (Passes < 26.87 cfs potential flow) 3=Sharp-Crested Rectangular Weir (Passes < 92.76 cfs potential flow) 4=Orifice/Grate (Orifice Controls 39.52 cfs @ 5.59 fps) Summary for Subcatchment 4S: ONSITE TO POA 1 Runoff = 82.04 cfs @ 11.95 hrs, Volume= 3.963 af, Depth> 6.44" 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=9.13" Area (ac) CN Description * 3.510 98 Impervious 3.570 61 >75% Grass cover, Good, HSG B 0.300 55 Woods, Good, HSG B 7.380 78 Weighted Average 3.870 52.44% Pervious Area 3.510 47.56% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, 63 POSTDEV TOTAL Type II 24-hr 100-YR Rainfall=9.13"POSTDEV TOTAL Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 19HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Subcatchment 5S: OFFSITE TO POA 1 VIA E9 (TOC II) Runoff = 72.93 cfs @ 12.16 hrs, Volume= 5.988 af, Depth= 5.70" 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=9.13" Area (ac) CN Description 12.610 72 1/3 acre lots, 30% imp, HSG B 8.827 70.00% Pervious Area 3.783 30.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 23.2 Direct Entry, Summary for Subcatchment 6S: OFFSITE TO POA 1 VIA E7C (TOC III) Runoff = 194.10 cfs @ 12.23 hrs, Volume= 18.293 af, Depth= 5.70" 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=9.13" Area (ac) CN Description 38.520 72 1/3 acre lots, 30% imp, HSG B 26.964 70.00% Pervious Area 11.556 30.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 29.0 Direct Entry, Summary for Subcatchment 7S: OFFSITE TO POA 1 VIA DITCH 1 (TOC IV) Runoff = 18.94 cfs @ 12.09 hrs, Volume= 1.290 af, Depth= 5.45" 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=9.13" Area (ac) CN Description 2.840 70 1/2 acre lots, 25% imp, HSG B 2.130 75.00% Pervious Area 0.710 25.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 16.5 Direct Entry, 64 POSTDEV TOTAL Type II 24-hr 100-YR Rainfall=9.13"POSTDEV TOTAL Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 20HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Subcatchment 8S: OFFSITE TO POA 1 VIA G2 (TOC V) Runoff = 251.62 cfs @ 12.71 hrs, Volume= 42.674 af, Depth= 5.70" 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=9.13" Area (ac) CN Description 89.860 72 1/3 acre lots, 30% imp, HSG B 62.902 70.00% Pervious Area 26.958 30.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 67.3 Direct Entry, Summary for Subcatchment 9S: OFFSITE TO POA 1 VIA G2 (TOC VI) Runoff = 295.58 cfs @ 12.74 hrs, Volume= 51.965 af, Depth= 3.95" 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=9.13" Area (ac) CN Description 157.700 58 Woods/grass comb., Good, HSG B 157.700 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 67.6 Direct Entry, Summary for Link 10L: POA 1 Inflow Area = 336.760 ac, 14.66% Impervious, Inflow Depth = 4.77" for 100-YR event Inflow = 666.89 cfs @ 12.60 hrs, Volume= 133.893 af Primary = 666.89 cfs @ 12.60 hrs, Volume= 133.893 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Summary for Subcatchment 11S: ONSITE TO POA 2 Runoff = 40.80 cfs @ 11.96 hrs, Volume= 1.916 af, Depth= 5.45" 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=9.13" 65 POSTDEV TOTAL Type II 24-hr 100-YR Rainfall=9.13"POSTDEV TOTAL Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 21HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Area (ac) CN Description 1.500 61 >75% Grass cover, Good, HSG B * 1.220 98 Impervious 1.500 55 Woods, Good, HSG B 4.220 70 Weighted Average 3.000 71.09% Pervious Area 1.220 28.91% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 12S: OFFSITE TO POA 2 VIA A2 (TOC VII) Runoff = 334.55 cfs @ 12.45 hrs, Volume= 43.987 af, Depth= 3.95" 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=9.13" Area (ac) CN Description 133.490 58 Woods/grass comb., Good, HSG B 133.490 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 45.5 Direct Entry, Summary for Link 13L: POA 2 Inflow Area = 474.470 ac, 10.66% Impervious, Inflow Depth = 4.55" for 100-YR event Inflow = 995.31 cfs @ 12.49 hrs, Volume= 179.797 af Primary = 995.31 cfs @ 12.49 hrs, Volume= 179.797 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Summary for Subcatchment 14S: ONSITE TO POA 3 Runoff = 6.91 cfs @ 11.96 hrs, Volume= 0.320 af, Depth= 3.95" 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=9.13" Area (ac) CN Description 0.500 55 Woods, Good, HSG B 0.470 61 >75% Grass cover, Good, HSG B 0.970 58 Weighted Average 0.970 100.00% Pervious Area 66 POSTDEV TOTAL Type II 24-hr 100-YR Rainfall=9.13"POSTDEV TOTAL Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 22HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Link 15L: POA 3 (COW BRANCH) Inflow Area = 475.440 ac, 10.64% Impervious, Inflow Depth = 4.55" for 100-YR event Inflow = 995.94 cfs @ 12.49 hrs, Volume= 180.117 af Primary = 995.94 cfs @ 12.49 hrs, Volume= 180.117 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs 67 1S ONSITE TO BMP 1 VIA F3&F4 4S ONSITE TO POA 1 10L POA 1 11S ONSITE TO POA 2 13L POA 2 14S ONSITE TO POA 3 15L POA 3 (COW BRANCH) Drainage Diagram for POSTDEV ONSITE FOR EBE Prepared by Shimp Engineering, P.C., Printed 7/2/2020 HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Subcat Reach Pond Link 68 POSTDEV ONSITE Type II 24-hr 1-YR Rainfall=3.04"POSTDEV ONSITE FOR EBE Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 2HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC 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 Runoff Area=1.130 ac 55.75% Impervious Runoff Depth=1.41"Subcatchment 1S: ONSITE TO BMP 1 VIA Tc=5.0 min CN=82 Runoff=2.87 cfs 0.133 af Runoff Area=7.380 ac 47.56% Impervious Runoff Depth=1.16"Subcatchment 4S: ONSITE TO POA 1 Tc=5.0 min CN=78 Runoff=15.35 cfs 0.712 af Inflow=18.22 cfs 0.845 afLink 10L: POA 1 Primary=18.22 cfs 0.845 af Runoff Area=4.220 ac 28.91% Impervious Runoff Depth=0.74"Subcatchment 11S: ONSITE TO POA 2 Tc=5.0 min CN=70 Runoff=5.31 cfs 0.259 af Inflow=23.51 cfs 1.104 afLink 13L: POA 2 Primary=23.51 cfs 1.104 af Runoff Area=0.970 ac 0.00% Impervious Runoff Depth=0.29"Subcatchment 14S: ONSITE TO POA 3 Tc=5.0 min CN=58 Runoff=0.31 cfs 0.023 af Inflow=23.75 cfs 1.127 afLink 15L: POA 3 (COW BRANCH) Primary=23.75 cfs 1.127 af Total Runoff Area = 13.700 ac Runoff Volume = 1.127 af Average Runoff Depth = 0.99" 60.88% Pervious = 8.340 ac 39.12% Impervious = 5.360 ac 69 POSTDEV ONSITE Type II 24-hr 1-YR Rainfall=3.04"POSTDEV ONSITE FOR EBE Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 3HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: ONSITE TO BMP 1 VIA F3&F4 Runoff = 2.87 cfs @ 11.96 hrs, Volume= 0.133 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 1-YR Rainfall=3.04" Area (ac) CN Description 0.500 61 >75% Grass cover, Good, HSG B * 0.630 98 Impervious 1.130 82 Weighted Average 0.500 44.25% Pervious Area 0.630 55.75% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 4S: ONSITE TO POA 1 Runoff = 15.35 cfs @ 11.96 hrs, Volume= 0.712 af, Depth= 1.16" 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=3.04" Area (ac) CN Description * 3.510 98 Impervious 3.570 61 >75% Grass cover, Good, HSG B 0.300 55 Woods, Good, HSG B 7.380 78 Weighted Average 3.870 52.44% Pervious Area 3.510 47.56% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Link 10L: POA 1 Inflow Area = 8.510 ac, 48.65% Impervious, Inflow Depth = 1.19" for 1-YR event Inflow = 18.22 cfs @ 11.96 hrs, Volume= 0.845 af Primary = 18.22 cfs @ 11.96 hrs, Volume= 0.845 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs 70 POSTDEV ONSITE Type II 24-hr 1-YR Rainfall=3.04"POSTDEV ONSITE FOR EBE Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 4HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Subcatchment 11S: ONSITE TO POA 2 Runoff = 5.31 cfs @ 11.97 hrs, Volume= 0.259 af, Depth= 0.74" 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=3.04" Area (ac) CN Description 1.500 61 >75% Grass cover, Good, HSG B * 1.220 98 Impervious 1.500 55 Woods, Good, HSG B 4.220 70 Weighted Average 3.000 71.09% Pervious Area 1.220 28.91% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Link 13L: POA 2 Inflow Area = 12.730 ac, 42.11% Impervious, Inflow Depth = 1.04" for 1-YR event Inflow = 23.51 cfs @ 11.96 hrs, Volume= 1.104 af Primary = 23.51 cfs @ 11.96 hrs, Volume= 1.104 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Summary for Subcatchment 14S: ONSITE TO POA 3 Runoff = 0.31 cfs @ 12.00 hrs, Volume= 0.023 af, Depth= 0.29" 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=3.04" Area (ac) CN Description 0.500 55 Woods, Good, HSG B 0.470 61 >75% Grass cover, Good, HSG B 0.970 58 Weighted Average 0.970 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, 71 POSTDEV ONSITE Type II 24-hr 1-YR Rainfall=3.04"POSTDEV ONSITE FOR EBE Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 5HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Link 15L: POA 3 (COW BRANCH) Inflow Area = 13.700 ac, 39.12% Impervious, Inflow Depth = 0.99" for 1-YR event Inflow = 23.75 cfs @ 11.96 hrs, Volume= 1.127 af Primary = 23.75 cfs @ 11.96 hrs, Volume= 1.127 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs 72 POSTDEV ONSITE Type II 24-hr 10-YR Rainfall=5.55"POSTDEV ONSITE FOR EBE Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 6HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC 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 Runoff Area=1.130 ac 55.75% Impervious Runoff Depth=3.58"Subcatchment 1S: ONSITE TO BMP 1 VIA Tc=5.0 min CN=82 Runoff=7.09 cfs 0.337 af Runoff Area=7.380 ac 47.56% Impervious Runoff Depth=3.18"Subcatchment 4S: ONSITE TO POA 1 Tc=5.0 min CN=78 Runoff=41.87 cfs 1.958 af Inflow=48.96 cfs 2.295 afLink 10L: POA 1 Primary=48.96 cfs 2.295 af Runoff Area=4.220 ac 28.91% Impervious Runoff Depth=2.45"Subcatchment 11S: ONSITE TO POA 2 Tc=5.0 min CN=70 Runoff=18.66 cfs 0.863 af Inflow=67.61 cfs 3.158 afLink 13L: POA 2 Primary=67.61 cfs 3.158 af Runoff Area=0.970 ac 0.00% Impervious Runoff Depth=1.48"Subcatchment 14S: ONSITE TO POA 3 Tc=5.0 min CN=58 Runoff=2.50 cfs 0.120 af Inflow=70.09 cfs 3.278 afLink 15L: POA 3 (COW BRANCH) Primary=70.09 cfs 3.278 af Total Runoff Area = 13.700 ac Runoff Volume = 3.278 af Average Runoff Depth = 2.87" 60.88% Pervious = 8.340 ac 39.12% Impervious = 5.360 ac 73 POSTDEV ONSITE Type II 24-hr 10-YR Rainfall=5.55"POSTDEV ONSITE FOR EBE Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 7HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: ONSITE TO BMP 1 VIA F3&F4 Runoff = 7.09 cfs @ 11.95 hrs, Volume= 0.337 af, Depth= 3.58" 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=5.55" Area (ac) CN Description 0.500 61 >75% Grass cover, Good, HSG B * 0.630 98 Impervious 1.130 82 Weighted Average 0.500 44.25% Pervious Area 0.630 55.75% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 4S: ONSITE TO POA 1 Runoff = 41.87 cfs @ 11.96 hrs, Volume= 1.958 af, Depth= 3.18" 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=5.55" Area (ac) CN Description * 3.510 98 Impervious 3.570 61 >75% Grass cover, Good, HSG B 0.300 55 Woods, Good, HSG B 7.380 78 Weighted Average 3.870 52.44% Pervious Area 3.510 47.56% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Link 10L: POA 1 Inflow Area = 8.510 ac, 48.65% Impervious, Inflow Depth = 3.24" for 10-YR event Inflow = 48.96 cfs @ 11.96 hrs, Volume= 2.295 af Primary = 48.96 cfs @ 11.96 hrs, Volume= 2.295 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs 74 POSTDEV ONSITE Type II 24-hr 10-YR Rainfall=5.55"POSTDEV ONSITE FOR EBE Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 8HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Subcatchment 11S: ONSITE TO POA 2 Runoff = 18.66 cfs @ 11.96 hrs, Volume= 0.863 af, Depth= 2.45" 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=5.55" Area (ac) CN Description 1.500 61 >75% Grass cover, Good, HSG B * 1.220 98 Impervious 1.500 55 Woods, Good, HSG B 4.220 70 Weighted Average 3.000 71.09% Pervious Area 1.220 28.91% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Link 13L: POA 2 Inflow Area = 12.730 ac, 42.11% Impervious, Inflow Depth = 2.98" for 10-YR event Inflow = 67.61 cfs @ 11.96 hrs, Volume= 3.158 af Primary = 67.61 cfs @ 11.96 hrs, Volume= 3.158 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Summary for Subcatchment 14S: ONSITE TO POA 3 Runoff = 2.50 cfs @ 11.97 hrs, Volume= 0.120 af, Depth= 1.48" 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=5.55" Area (ac) CN Description 0.500 55 Woods, Good, HSG B 0.470 61 >75% Grass cover, Good, HSG B 0.970 58 Weighted Average 0.970 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, 75 POSTDEV ONSITE Type II 24-hr 10-YR Rainfall=5.55"POSTDEV ONSITE FOR EBE Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 9HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Link 15L: POA 3 (COW BRANCH) Inflow Area = 13.700 ac, 39.12% Impervious, Inflow Depth = 2.87" for 10-YR event Inflow = 70.09 cfs @ 11.96 hrs, Volume= 3.278 af Primary = 70.09 cfs @ 11.96 hrs, Volume= 3.278 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs 76 POSTDEV ONSITE Type II 24-hr 100-YR Rainfall=9.13"POSTDEV ONSITE FOR EBE Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 10HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC 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 Runoff Area=1.130 ac 55.75% Impervious Runoff Depth>6.93"Subcatchment 1S: ONSITE TO BMP 1 VIA Tc=5.0 min CN=82 Runoff=13.26 cfs 0.653 af Runoff Area=7.380 ac 47.56% Impervious Runoff Depth>6.44"Subcatchment 4S: ONSITE TO POA 1 Tc=5.0 min CN=78 Runoff=82.04 cfs 3.963 af Inflow=95.31 cfs 4.616 afLink 10L: POA 1 Primary=95.31 cfs 4.616 af Runoff Area=4.220 ac 28.91% Impervious Runoff Depth=5.45"Subcatchment 11S: ONSITE TO POA 2 Tc=5.0 min CN=70 Runoff=40.80 cfs 1.916 af Inflow=136.10 cfs 6.532 afLink 13L: POA 2 Primary=136.10 cfs 6.532 af Runoff Area=0.970 ac 0.00% Impervious Runoff Depth=3.95"Subcatchment 14S: ONSITE TO POA 3 Tc=5.0 min CN=58 Runoff=6.91 cfs 0.320 af Inflow=142.99 cfs 6.852 afLink 15L: POA 3 (COW BRANCH) Primary=142.99 cfs 6.852 af Total Runoff Area = 13.700 ac Runoff Volume = 6.852 af Average Runoff Depth = 6.00" 60.88% Pervious = 8.340 ac 39.12% Impervious = 5.360 ac 77 POSTDEV ONSITE Type II 24-hr 100-YR Rainfall=9.13"POSTDEV ONSITE FOR EBE Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 11HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: ONSITE TO BMP 1 VIA F3&F4 Runoff = 13.26 cfs @ 11.95 hrs, Volume= 0.653 af, Depth> 6.93" 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=9.13" Area (ac) CN Description 0.500 61 >75% Grass cover, Good, HSG B * 0.630 98 Impervious 1.130 82 Weighted Average 0.500 44.25% Pervious Area 0.630 55.75% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 4S: ONSITE TO POA 1 Runoff = 82.04 cfs @ 11.95 hrs, Volume= 3.963 af, Depth> 6.44" 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=9.13" Area (ac) CN Description * 3.510 98 Impervious 3.570 61 >75% Grass cover, Good, HSG B 0.300 55 Woods, Good, HSG B 7.380 78 Weighted Average 3.870 52.44% Pervious Area 3.510 47.56% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Link 10L: POA 1 Inflow Area = 8.510 ac, 48.65% Impervious, Inflow Depth > 6.51" for 100-YR event Inflow = 95.31 cfs @ 11.95 hrs, Volume= 4.616 af Primary = 95.31 cfs @ 11.95 hrs, Volume= 4.616 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs 78 POSTDEV ONSITE Type II 24-hr 100-YR Rainfall=9.13"POSTDEV ONSITE FOR EBE Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 12HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Subcatchment 11S: ONSITE TO POA 2 Runoff = 40.80 cfs @ 11.96 hrs, Volume= 1.916 af, Depth= 5.45" 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=9.13" Area (ac) CN Description 1.500 61 >75% Grass cover, Good, HSG B * 1.220 98 Impervious 1.500 55 Woods, Good, HSG B 4.220 70 Weighted Average 3.000 71.09% Pervious Area 1.220 28.91% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Link 13L: POA 2 Inflow Area = 12.730 ac, 42.11% Impervious, Inflow Depth > 6.16" for 100-YR event Inflow = 136.10 cfs @ 11.95 hrs, Volume= 6.532 af Primary = 136.10 cfs @ 11.95 hrs, Volume= 6.532 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Summary for Subcatchment 14S: ONSITE TO POA 3 Runoff = 6.91 cfs @ 11.96 hrs, Volume= 0.320 af, Depth= 3.95" 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=9.13" Area (ac) CN Description 0.500 55 Woods, Good, HSG B 0.470 61 >75% Grass cover, Good, HSG B 0.970 58 Weighted Average 0.970 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, 79 POSTDEV ONSITE Type II 24-hr 100-YR Rainfall=9.13"POSTDEV ONSITE FOR EBE Printed 7/2/2020Prepared by Shimp Engineering, P.C. Page 13HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Summary for Link 15L: POA 3 (COW BRANCH) Inflow Area = 13.700 ac, 39.12% Impervious, Inflow Depth > 6.00" for 100-YR event Inflow = 142.99 cfs @ 11.95 hrs, Volume= 6.852 af Primary = 142.99 cfs @ 11.95 hrs, Volume= 6.852 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs 80 1-YEAR STORM ANALYSIS:To meet Energy Balance Requirements, Redude Flow @ POA 1 by:= required reduction @ POA0.52-0.02 =0.50 cfs 1-YRQpre= 42.7354.73POA 1 Onsite Runoff:Inflow Area = 8.51 ac10-YRQpre= 212.33268.51Qpre-developed=0.52-12.00 cfsRVPre-Developed=0.034Max Qdeveloped= 0.02 cfsRVDeveloped=0.845.Qpre=212.33 cfsQpost=268.51 cfs1-YEAR STORM ANALYSIS:To meet Energy Balance Requirements, Redude Flow @ POA 2 by:= required reduction @ POA9.24-5.12 =4.12 cfs 1-YRQpre= 72.4067.19POA 2 Onsite Runoff:Inflow Area = 12.73 ac10-YRQpre= 385.89377.20Qpre-developed=9.245.21 cfsRVPre-Developed=0.764Max Qdeveloped= 5.12 cfsRVDeveloped=1.104Qpre=384.12 cfsQpost=377.20 cfs1-YEAR STORM ANALYSIS:To meet Energy Balance Requirements, Reduce Flow @ POA 3 by:= required reduction @ POA9.46-5.32 =4.14 cfs 1-YRQpre= 72.4567.24POA 3 Entire Site Runoff:Inflow Area = 13.70 ac10-YRQpre= 386.16377.44Qpre-developed=9.465.21 cfsRVPre-Developed=0.792Max Qdeveloped= 5.32 cfsRVDeveloped=1.127Qpre=9.52 cfsQpost=9.08 cfs10-YR ReductionACHIEVED REDUCTION AT POA 3:ACHIEVEDPOSTDEVEnergy Balance Equation Summary for POA 1Galaxie Farm 24 Hr 1 year Storm Comparison:Qdeveloped≤ I.F. *(Qpre-developed*RVPre-Developed)/RvdevelopedPREDEVSince the 1-yr reduction is greater than the reduction required by the Energy Balance Equation, Runoff at this POA is compliant.10-YEAR STORM:Qpost=requiredQpost=ACHIEVED REDUCTION AT POA 1:Galaxie Farm 24 Hr 1 year Storm Comparison:Qdeveloped≤ I.F. *(Qpre-developed*RVPre-Developed)/RvdevelopedQdeveloped≤ (Qforested*RVforested)/RvdevelopedAchieved Post-Dev Peak Runoff Q1yr = 0.38 cfs. Site complies with 9VAC25-870-66-B(3)arequired10-YEAR STORM:Qdeveloped≤ (Qforested*RVforested)/RvdevelopedAchieved Post-Dev Peak Runoff Q1yr = 54.73 cfs. Point discharges to a restored channel to comply with 9VAC25-870-66-B(2)NOT ACHIEVED1-YR ReductionEnergy Balance Equation Summary for POA 2Energy Balance Equation Summary-12.00Qdeveloped≤ (Qforested*RVforested)/RvdevelopedPREDEVPOSTDEVrequiredQpost=10-YEAR STORM:ACHIEVED REDUCTION AT POA 2:ACHIEVED1-YR Reduction10-YR ReductionTotal Runoff (Including Offsite)(Qpre-Qmax)(Qpre-Qmax)(Qpre-Qmax)Note: Since the 1-yr reduction is greater than the reduction required by the Energy Balance Equation, Runoff at this POA is compliant.5.21Qpost=Qpost=8.69-56.18Qpost=1-YR Reduction10-YR ReductionSite complies with 9VAC25-870-66-C(2)bSite complies with 9VAC25-870-66-C(2)bSite complies with 9VAC25-870-66-C(2)a since the channel is desgined for this flow.Total Runoff (Including Offsite)Achieved Post-Dev Peak Runoff Q1yr = 67.19 cfs. Site complies with 9VAC25-870-66-B(3)aGalaxie Farm 24 Hr 1 year Storm Comparison:Qdeveloped≤ I.F. *(Qpre-developed*RVPre-Developed)/Rvdeveloped5.218.72Note: Since reduction is not achieved, the channel between POA 1 and POA 2 will be restored to the point in the natural channel where energy balance equation is met (at POA 2).Total Runoff (Including Offsite)PREDEVPOSTDEV 81 GALAXIE FARM PREDEV VRRM MAP TOTAL SITE AREA: 13.70 AC ALL AREAS ARE HSG B WOODS: 3.89 AC TURF: 9.21 AC IMPERV: 0.60 AC IMP. WOODS WOODS TURF TURF TURF IMP. 82 GALAXIE FARM POSTDEV VRRM MAP TOTAL SITE AREA: 13.70 AC ALL AREAS ARE HSG B WOODS: 2.80 AC TURF: 5.50 AC IMPERV: 5.40 AC FOR VRRM CALCS, ONLY AREAS THAT WILL BE PLACED WITHIN A SWM FOREST/ OPEN SPACE EASEMENT ARE CLAIMED AS WOODS. REQUIRED VRRM TOTAL PHOSPHOROUS REDUCTION: 8.78 LB/YR ACHIEVED TOTAL PHOSPHOROUS TREATMENT FROM BMP 1 (ADS STORMTECH ISOLATOR ROW ): 2.22 LB/YR ONSITE TREATMENT PERCENTAGE: 2.22/8.78 = 0.253 = 25.3% REMAINING TP TREATMENT REQUIRED: 6.56 LB/YR. THIS WILL BE SATISFIED WITH THE PURCHASE OF OFFSITE NUTRIENT CREDITS. IMP. WOODS WOODS TURF TURF TURF IMP. IMP. BMP 1 83 Project Name: Date: Linear Development Project?No Site Information Post-Development Project (Treatment Volume and Loads) 12.00 TRUE 20%Linear project?No The site's net increase in impervious cover (acres) is: 4.8 ✔ Post-Development TP Load Reduction for Site (lb/yr): 8.78 ✔ Pre-ReDevelopment Land Cover (acres) A Soils B Soils C Soils D Soils Totals Forest/Open Space (acres) -- undisturbed forest/open space 3.89 3.89 Managed Turf (acres) -- disturbed, graded for yards or other turf to be mowed/managed 9.21 9.21 Impervious Cover (acres)0.60 0.60 13.70 Post-Development Land Cover (acres) A Soils B Soils C Soils D Soils Totals Forest/Open Space (acres) -- undisturbed, protected forest/open space or reforested land 2.80 2.80 * Managed Turf (acres) -- disturbed, graded for yards or other turf to be mowed/managed 5.50 5.50 Impervious Cover (acres)5.40 5.40 Area Check OK.OK.OK.OK.13.70 * Forest/Open Space areas must be protected in accordance with the Virginia Runoff Reduction Method Constants Runoff Coefficients (Rv) Annual Rainfall (inches)43 A Soils B Soils C Soils D Soils Target Rainfall Event (inches)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/yr)0.41 Pj (unitless correction factor)0.90 Pre-ReDevelopment Listed Adjusted1 Forest/Open Space Cover (acres)3.89 2.80 Forest/Open Space Cover (acres)2.80 Forest/Open Space Cover (acres)2.80 Weighted Rv(forest)0.03 0.03 Weighted Rv(forest)0.03 Weighted Rv(forest)0.03 % Forest 28%31%% Forest 20%% Forest 31% Managed Turf Cover (acres)9.21 5.50 Managed Turf Cover (acres)5.50 Managed Turf Cover (acres)5.50 Weighted Rv(turf)0.20 0.20 Weighted Rv (turf)0.20 Weighted Rv (turf)0.20 % Managed Turf 67%62%% Managed Turf 40%% Managed Turf 62% Impervious Cover (acres)0.60 0.60 Impervious Cover (acres)5.40 ReDev. Impervious Cover (acres)0.60 New Impervious Cover (acres)4.80 Rv(impervious)0.95 0.95 Rv(impervious)0.95 Rv(impervious)0.95 Rv(impervious)0.95 % Impervious 4%7%% Impervious 39%% Impervious 7% Total Site Area (acres)13.70 8.90 Final Site Area (acres)13.70 Total ReDev. Site Area (acres)8.90 Site Rv 0.18 0.20 Final Post Dev Site Rv 0.46 ReDev Site Rv 0.20 Pre-ReDevelopment Treatment Volume (acre-ft) 0.2107 0.1462 Final Post-Development Treatment Volume (acre-ft) 0.5262 Post-ReDevelopment Treatment Volume (acre-ft) 0.1462 Post-Development Treatment Volume (acre-ft) 0.3800 Pre-ReDevelopment Treatment Volume (cubic feet) 9,179 6,367 Final Post-Development Treatment Volume (cubic feet) 22,920 Post-ReDevelopment Treatment Volume (cubic feet) 6,367 Post-Development Treatment Volume (cubic feet) 16,553 Pre-ReDevelopment TP Load (lb/yr)5.77 4.00 * Final Post- Development TP Load (lb/yr) 14.40 * Post-ReDevelopment Load (TP) (lb/yr)* 4.00 Post-Development TP Load (lb/yr)10.40 Pre-ReDevelopment TP Load per acre (lb/acre/yr)0.42 0.45 * Final Post-Development TP Load per acre (lb/acre/yr) 1.05 Post-ReDevelopment TP Load per acre (lb/acre/yr) 0.45 3.65 Max. Reduction Required (Below Pre- ReDevelopment Load) 20% * TP Load Reduction Required for Redeveloped Area (lb/yr) 0.35 TP Load Reduction Required for New Impervious Area (lb/yr) 8.43 * 8.78 GALAXIE FARM 7/2/2020 LAND COVER SUMMARY -- POST DEVELOPMENTLAND COVER SUMMARY -- PRE-REDEVELOPMENT Maximum reduction required: Enter Total Disturbed Area (acres) →Check: Land cover areas entered correctly? Total disturbed area entered? BMP Design Specifications List: Treatment Volume and Nutrient Load Land Cover Summary-Post (Final) 2013 Draft Stds & Specs Land Cover Summary-Pre Land Cover Summary-Post Post-ReDevelopment TP Load Reduction Required (lb/yr) Post-Development Requirement for Site Area Baseline TP Load (lb/yr) (0.41 lbs/acre/yr applied to pre-redevelopment area excluding pervious land proposed for new impervious cover) Reduction below new development load limitation not required 1 Adjusted Land Cover Summary: Pre ReDevelopment land cover minus pervious land cover (forest/open space or managed turf) acreage proposed for new impervious cover. Adjusted total acreage is consistent with Post-ReDevelopment acreage (minus acreage of new impervious cover). Column I shows load reduction requriement for new impervious cover (based on new development load limit, 0.41 lbs/acre/year). Post ReDev. & New Impervious Treatment Volume and Nutrient Load Land Cover Summary-Post Post-Development New Impervious CLEAR ALL (Ctrl+Shift+R) data input cells constant values calculation cells final results 84 VRRM ReDev Spreadsheet V3 GALAXIE D.A. A Drainage Area A Drainage Area A Land Cover (acres) A Soils B Soils C Soils D Soils Totals Land Cover Rv ` Forest/Open Space (acres)0.00 0.00 Managed Turf (acres)4.80 4.80 0.20 Impervious Cover (acres) 2.22 2.22 0.95 7.00 Total 7.02 11,140 Stormwater Best Management Practices (RR = Runoff Reduction)--Select from dropdown lists-- Practice Runoff Reduction Credit (%) Managed Turf Credit Area (acres) Impervious Cover Credit Area (acres) Volume from Upstream Practice (ft3) Runoff Reduction (ft3) Remaining Runoff Volume (ft3) Total BMP Treatment Volume (ft3) Phosphorus Removal Efficiency (%) Phosphorus Load from Upstream Practices (lb) Untreated Phosphorus Load to Practice (lb) Phosphorus Removed By Practice (lb) Remaining Phosphorus Load (lb) 1. Vegetated Roof (RR) 1.a. Vegetated Roof #1 (Spec #5)45 0 0 0 0 0.00 0.00 0.00 1.b. Vegetated Roof #2 (Spec #5)60 0 0 0 0 0.00 0.00 0.00 2. Rooftop Disconnection (RR) 2.a. Simple Disconnection to A/B Soils (Spec #1)50 0 0 0 0 0 0.00 0.00 0.00 0.00 2.b. Simple Disconnection to C/D Soils (Spec #1)25 0 0 0 0 0 0.00 0.00 0.00 0.00 2.c. To Soil Amended Filter Path as per specifications (existing C/D soils) (Spec #4)50 0 0 0 0 0 0.00 0.00 0.00 0.00 2.d. To Dry Well or French Drain #1, Micro-Infilration #1 (Spec #8)50 0 0 0 0 25 0.00 0.00 0.00 0.00 2.e. To Dry Well or French Drain #2, Micro-Infiltration #2 (Spec #8)90 0 0 0 0 25 0.00 0.00 0.00 0.00 2.f. To Rain Garden #1, Micro-Bioretention #1 (Spec #9)40 0 0 0 0 25 0.00 0.00 0.00 0.00 2.g. To Rain Garden #2, Micro-Bioretention #2 (Spec #9)80 0 0 0 0 50 0.00 0.00 0.00 0.00 2.h. To Rainwater Harvesting (Spec #6)0 0 0 0 0 0 0.00 0.00 0.00 0.00 2.i. To Stormwater Planter, Urban Bioretention (Spec #9, Appendix A)40 0 0 0 0 25 0.00 0.00 0.00 0.00 3. Permeable Pavement (RR) 3.a. Permeable Pavement #1 (Spec #7)45 0 0 0 0 25 0.00 0.00 0.00 0.00 3.b. Permeable Pavement #2 (Spec #7)75 0 0 0 25 0.00 0.00 0.00 4. Grass Channel (RR) 4.a. Grass Channel A/B Soils (Spec #3)20 0 0 0 0 15 0.00 0.00 0.00 0.00 4.b. Grass Channel C/D Soils (Spec #3)10 0 0 0 0 15 0.00 0.00 0.00 0.00 4.c. Grass Channel with Compost Amended Soils as per specs (see Spec #4)20 0 0 0 0 15 0.00 0.00 0.00 0.00 5. Dry Swale (RR) 5.a. Dry Swale #1 (Spec #10)40 0 0 0 0 20 0.00 0.00 0.00 0.00 5.b. Dry Swale #2 (Spec #10)60 0 0 0 0 40 0.00 0.00 0.00 0.00 6. Bioretention (RR) 6.a. Bioretention #1 or Micro-Bioretention #1 or Urban Bioretention (Spec #9)40 0 0 0 0 25 0.00 0.00 0.00 0.00 6.b. Bioretention #2 or Micro-Bioretention #2 (Spec #9)80 0 0 0 0 50 0.00 0.00 0.00 0.00 7. Infiltration (RR) 7.a. Infiltration #1 (Spec #8)50 0 0 0 0 25 0.00 0.00 0.00 0.00 7.b. Infiltration #2 (Spec #8)90 0 0 0 0 25 0.00 0.00 0.00 0.00 8. Extended Detention Pond (RR) 8.a. ED #1 (Spec #15)0 0 0 0 0 15 0.00 0.00 0.00 0.00 8.b. ED #2 (Spec #15)15 0 0 0 0 15 0.00 0.00 0.00 0.00 9. Sheetflow to Filter/Open Space (RR) 9.a. Sheetflow to Conservation Area, A/B Soils (Spec #2)75 0 0 0 0 0 0.00 0.00 0.00 0.00 9.b. Sheetflow to Conservation Area, C/D Soils (Spec #2)50 0 0 0 0 0 0.00 0.00 0.00 0.00 9.c. Sheetflow to Vegetated Filter Strip, A Soils or Compost Amended B/C/D Soils (Spec #2 & #4) 50 0 0 0 0 0 0.00 0.00 0.00 0.00 TOTAL IMPERVIOUS COVER TREATED (ac)0.00 AREA CHECK:OK. TOTAL MANAGED TURF AREA TREATED (ac)0.00 AREA CHECK:OK. TOTAL RUNOFF REDUCTION IN D.A. A (ft3)0 TOTAL PHOSPHORUS AVAILABLE FOR REMOVAL IN D.A. A (lb/yr)7.00 TOTAL PHOSPHORUS REMOVED WITH RUNOFF REDUCTION PRACTICES IN D.A. A (lb/yr)0.00 TOTAL PHOSPHORUS REMAINING AFTER APPLYING RUNOFF REDUCTION PRACTICES IN D.A. A (lb/yr)7.00 SEE WATER QUALITY COMPLIANCE TAB FOR SITE COMPLIANCE CALCULATIONS 10. Wet Swale (no RR) 10.a. Wet Swale #1 (Spec #11)0 0 0 0 0 20 0.00 0.00 0.00 0.00 10.b. Wet Swale #2 (Spec #11)0 0 0 0 0 40 0.00 0.00 0.00 0.00 11. Filtering Practices (no RR) 11.a.Filtering Practice #1 (Spec #12)0 0 0 0 0 60 0.00 0.00 0.00 0.00 11.b. Filtering Practice #2 (Spec #12)0 0 0 0 0 65 0.00 0.00 0.00 0.00 12. Constructed Wetland (no RR) 12.a.Constructed Wetland #1 (Spec #13)0 0 0 0 0 50 0.00 0.00 0.00 0.00 12.b. Constructed Wetland #2 (Spec #13)0 0 0 0 0 75 0.00 0.00 0.00 0.00 13. Wet Ponds (no RR) 13.a. Wet Pond #1 (Spec #14)0 0 0 0 0 50 0.00 0.00 0.00 0.00 13.b. Wet Pond #1 (Coastal Plain) (Spec #14) 0 0 0 0 0 45 0.00 0.00 0.00 0.00 13.c. Wet Pond #2 (Spec #14)0 0 0 0 0 75 0.00 0.00 0.00 0.00 13.d. Wet Pond #2 (Coastal Plain) (Spec #14) 0 0 0 0 0 65 0.00 0.00 0.00 0.00 14.a. Manufactured Treatment Device- Hydrodynamic 0 0 0 0 0 20 0.00 0.00 0.00 0.00 14.b. Manufactured Treatment Device-Filtering 0 4.60 1.60 0 0 8,857 8,857 40 0.00 5.56 2.22 3.34 14.c. Manufactured Treatment Device-Generic 0 0 0 0 0 20 0.00 0.00 0.00 0.00 TOTAL IMPERVIOUS COVER TREATED (ac)1.60 AREA CHECK:OK. TOTAL MANAGED TURF AREA TREATED (ac)4.60 AREA CHECK:OK. TOTAL PHOSPHORUS REMOVAL REQUIRED ON SITE (lb/yr)8.78 TOTAL PHOSPHORUS AVAILABLE FOR REMOVAL IN D.A. A (lb/yr)7.00 TOTAL PHOSPHORUS REMOVED WITHOUT RUNOFF REDUCTION PRACTICES IN D.A. A (lb/yr)2.22 TOTAL PHOSPHORUS REMOVED WITH RUNOFF REDUCTION PRACTICES IN D.A. A (lb/yr)0.00 TOTAL PHOSPHORUS LOAD REDUCTION ACHIEVED IN D.A. A (lb/yr)2.22 TOTAL PHOSPHORUS REMAINING AFTER APPLYING BMP LOAD REDUCTIONS IN D.A. A (lb/yr)4.78 SEE WATER QUALITY COMPLIANCE TAB FOR SITE COMPLIANCE CALCULATIONS NITROGEN REMOVED WITH RUNOFF REDUCTION PRACTICES IN D.A. A (lb/yr)0.00 NITROGEN REMOVED WITHOUT RUNOFF REDUCTION PRACTICES IN D.A. A (lb/yr)0.00 TOTAL NITROGEN REMOVED IN D.A. A (lb/yr)0.00 Total Phosphorus Available for Removal in D.A. A (lb/yr) Post Development Treatment Volume in D.A. A (ft3) Downstream Practice to be Employed 14. Manufactured Treatment Devices (no RR) CLEAR BMP AREAS 1 of 1 7/2/2020 5:09 PM 85 Site Results (Water Quality Compliance)Area ChecksD.A. AD.A. BD.A. CD.A. DD.A. E AREA CHECKFOREST/OPEN SPACE (ac)0.000.000.000.000.00OK.IMPERVIOUS COVER (ac)2.220.000.000.000.00OK.IMPERVIOUS COVER TREATED (ac)1.600.000.000.000.00OK.MANAGED TURF AREA (ac)4.800.000.000.000.00OK.MANAGED TURF AREA TREATED (ac)4.600.000.000.000.00OK.AREA CHECK OK.OK.OK.OK.OK.Site Treatment Volume (ft3)22,920Runoff Reduction Volume and TP By Drainage AreaD.A. AD.A. BD.A. CD.A. DD.A. ETOTALRUNOFF REDUCTION VOLUME ACHIEVED (ft3)000000TP LOAD AVAILABLE FOR REMOVAL (lb/yr)7.000.000.000.000.007.00TP LOAD REDUCTION ACHIEVED (lb/yr)2.220.000.000.000.002.22TP LOAD REMAINING (lb/yr)4.780.000.000.000.004.78NITROGEN LOAD REDUCTION ACHIEVED (lb/yr)0.000.000.000.000.000.00Total Phosphorus LINEAR PROJECT:FINAL POST-DEVELOPMENT TP LOAD (lb/yr)14.40TP LOAD REDUCTION REQUIRED (lb/yr)8.78TP LOAD REDUCTION ACHIEVED (lb/yr)2.22TP LOAD REMAINING (lb/yr):12.18REMAINING TP LOAD REDUCTION REQUIRED (lb/yr):6.56Total Nitrogen (For Information Purposes)POST-DEVELOPMENT LOAD (lb/yr)103.02NITROGEN LOAD REDUCTION ACHIEVED (lb/yr)0.00REMAINING POST-DEVELOPMENT NITROGEN LOAD (lb/yr)103.02 86 Virginia Runoff Reduction Method WorksheetDEQ Virginia Runoff Reduction Method Re-Development Compliance Spreadsheet - Version 3.0 BMP Design Specifications List:2013 Draft Stds & Specs Date: 44014 43 12.00 Site Land Cover Summary Pre-ReDevelopment Land Cover (acres) A soils B Soils C Soils D Soils Totals % of Total Forest/Open (acres)0.00 3.89 0.00 0.00 3.89 28 Managed Turf (acres)0.00 9.21 0.00 0.00 9.21 67 Impervious Cover (acres)0.00 0.60 0.00 0.00 0.60 4 13.70 100 Post-ReDevelopment Land Cover (acres) A soils B Soils C Soils D Soils Totals % of Total Forest/Open (acres)0.00 2.80 0.00 0.00 2.80 20 * Managed Turf (acres)0.00 5.50 0.00 0.00 5.50 40 Impervious Cover (acres)0.00 5.40 0.00 0.00 5.40 39 * Forest/Open Space areas must be protected in accordance with the Virginia Runoff Reduction Method 13.70 100 Site Tv and Land Cover Nutrient Loads Post- ReDevelopment Post- Development (New Impervious) Adjusted Pre- ReDevelopment Pre- ReDevelopment TP Load per acre (lb/acre/yr) Final Post-Development TP Load per acre (lb/acre/yr) Post-ReDevelopment TP Load per acre (lb/acre/yr) Site Rv 0.20 0.95 0.20 0.45 1.05 0.45 Treatment Volume (ft3) 6,367 16,553 6,367 TP Load (lb/yr)4.00 10.40 4.00 Baseline TP Load (lb/yr):3.649**Reduction below new development load limitation not required Total TP Load Reduction Required (lb/yr)0.35 8.43 Pre- ReDevelopment TN Load (lb/yr)41.26 Site Compliance Summary * Note: % Reduction will reduce post-development TP load to less than or equal to baseline load of 3.65 lb/yr (0.41 lb/ac/yr) [Required reduction for Post-ReDev. = Post-ReDev TP load - baseline load of 3.649 lb/yr], baseline load = site area x 0.41 lb/ac/yr Total Runoff Volume Reduction (ft3) 0 Total TP Load Reduction Achieved (lb/yr)2.22 Total TN Load Reduction Achieved (lb/yr)0.00 Remaining Post Development TP Load (lb/yr)12.18 Remaining TP Load Reduction (lb/yr) Required 6.56 Drainage Area Summary D.A. A D.A. B D.A. C D.A. D D.A. E Total Forest/Open (acres)0.00 0.00 0.00 0.00 0.00 0.00 Managed Turf (acres)4.80 0.00 0.00 0.00 0.00 4.80 Impervious Cover (acres)2.22 0.00 0.00 0.00 0.00 2.22 Total Area (acres)7.02 0.00 0.00 0.00 0.00 7.02 Drainage Area Compliance Summary D.A. A D.A. B D.A. C D.A. D D.A. E Total TP Load Reduced (lb/yr)2.22 0.00 0.00 0.00 0.00 2.22 TN Load Reduced (lb/yr)0.00 0.00 0.00 0.00 0.00 0.00 Drainage Area A Summary Land Cover Summary A Soils B Soils C Soils D Soils Total % of Total Forest/Open (acres)0.00 0.00 0.00 0.00 0.00 0 Managed Turf (acres)0.00 4.80 0.00 0.00 4.80 68 Impervious Cover (acres)0.00 2.22 0.00 0.00 2.22 32 7.02 BMP Selections Practice Managed Turf Credit Area (acres) Impervious Cover Credit Area (acres) BMP Treatment Volume (ft3) TP Load from Upstream Practices (lbs) Untreated TP Load to Practice (lbs) TP Removed (lb/yr) TP Remaining (lb/yr) Downstream Treatment to be Employed 14.b. Manufactured Treatment Device- Filtering 4.6 1.6 8,857.20 0.00 5.56 2.22 3.34 Total Impervious Cover Treated (acres)1.60 Total Turf Area Treated (acres) 4.60 Total TP Load Reduction Achieved in D.A. (lb/yr)2.22 Total TN Load Reduction Achieved in D.A. (lb/yr)0.00 Final Post-Development Load (Post-ReDevelopment & New Impervious) 103.02 Maximum % Reduction Required Below Pre-ReDevelopment Load 20% 8.78 Final Post-Development (Post-ReDevelopment & New Impervious) 0.46 22,920 14.40 Total Disturbed Acreage: Total Rainfall (in): Site Summary Project Title: GALAXIE FARM *Reduction below new development load limitation not required Summary Print 87 Virginia Runoff Reduction Method Worksheet Runoff Volume and CN Calculations 1-year storm 2-year storm 10-year storm Target Rainfall Event (in)3.04 3.67 5.55 Drainage Areas RV & CN Drainage Area A Drainage Area B Drainage Area C Drainage Area D Drainage Area E CN 73 0 0 0 0 RR (ft3)0 0 0 0 0 RV wo RR (ws-in)0.88 0.00 0.00 0.00 0.00 RV w RR (ws-in)0.88 0.00 0.00 0.00 0.00 CN adjusted 73 0 0 0 0 RV wo RR (ws-in)1.30 0.00 0.00 0.00 0.00 RV w RR (ws-in)1.30 0.00 0.00 0.00 0.00 CN adjusted 73 0 0 0 0 RV wo RR (ws-in)2.72 0.00 0.00 0.00 0.00 RV w RR (ws-in)2.72 0.00 0.00 0.00 0.00 CN adjusted 73 0 0 0 0 1-year return period 2-year return period 10-year return period Summary Print 88 Galaxie Farm Inlet Drainage Area Summary Impervious C 0.9 Pervious C 0.3 Woods C 0.2 To Inlet Area Impervious Turf C A G2 10,943,095 2,188,619 8,754,476 0.42 251.22 F4 18,600 11,440 7,160 0.67 0.43 F3 27,270 13,700 13,570 0.60 0.63 F2 1,248,870 90,432 1,158,439 0.34 28.67 F1 00 0 0 0.71 0.00 E9 468,399 132,173 336,226 0.47 10.75 E8A 20,483 14,310 6,173 0.72 0.47 E8 39,982 19,230 20,752 0.59 0.92 E7C 1,702,368 510,710 1,191,657 0.22 39.08 E7A 10,746 7,344 3,402 0.71 0.25 E7 19,955 9,973 9,982 0.60 0.46 E6Z 00 0 0 0.30 0.00 E6A 17,762 12,437 5,325 0.72 0.41 E6 29,652 12,140 17,512 0.55 0.68 E5 55,189 26,235 28,954 0.59 1.27 E4 6,430 5,100 1,330 0.78 0.15 E3 17,780 12,446 5,334 0.72 0.41 E2 26,021 16,731 9,290 0.69 0.60 D3 51,625 18,486 33,139 0.51 1.19 D2 22,451 8,890 13,561 0.54 0.52 C3 12,692 10,935 1,757 0.82 0.29 C2 6,038 5,570 468 0.85 0.14 B2 14,726,791 3,092,626 11,634,165 0.43 338.08 A2 5,802,223 1,160,445 4,641,778 0.42 133.20 Ditch 1 159,704 38,751 120,953 0.45 3.67 89 X-TO PO --Y-PL AT --251.22 ACTO G2133.20 ACTO A2338.08 ACTOTAL TO B286.87 ACADDED TO B2TO C V I = 6 7 . 3 M I N TOC VII=45.5 MINGALAXIE FARMPOSTDEV CULVERTDRAINAGE MAP 90 SHEETFLOWRUNOFFAREA3.67 AC TO DITCH 112.62 ACTO E939.08 AC TO E7C26.61 AC TO F20.95 AC TO E80.47 AC TO E8A0.48 AC TO E70.25 AC TO E7A0.68 AC TO E60.41 AC TO E6A0.41 AC TO E31.27 AC TO E50.60 ACTO E20.15 AC TO E4 SHEETFLOWRUNOFFAREA0.63 AC TO F30.43 ACTO F41.19 ACTO D30.52 ACTO D20.29 AC TO C30.14 AC TO C2GALAXIE FARMPOSTDEV INLETDRAINAGE MAPS T A T E R T E 2 0 91 SHEETFLOW RUNOFF AREA 3.67 AC TO DITCH 1 12.62 AC TO E9 39.08 AC TO E7C 26.61 AC TO F2 0.95 AC TO E8 0.47 AC TO E8A 0.48 AC TO E7 0.25 AC TO E7A 0.68 AC TO E6 0.41 AC TO E6A 0.41 AC TO E3 1.27 AC TO E5 0.60 AC TO E20.15 ACTO E4SHEETFLOW RUNOFF AREA 0.63 AC TO F30.43 AC TO F4 1.19 AC TO D3 0.52 AC TO D2 0.29 AC TO C3 0.14 AC TO C2 GALAXIE FARM POSTDEV INLET DRAINAGE MAP (OFFSITE INCLUDED)STATE RTE 20 92 Culvert A 133.2 Ac 927.5 ft 4440 ft 0.208 sq mi 0.84 mi Storm Q2 48.5 cfs 122(A)0.635 45.0 cfs Q10 147.1 cfs 335(A)0.596 131.5 cfs Q25 227.0 cfs 504(A)0.581 202.5 cfs Q50 301.5 cfs 661(A)0.570 270.2 cfs Q100 384.8 cfs 849(A)0.559 353.1 cfs Culvert B 338.1 Ac 927.5 ft 6411 ft 0.528 sq mi 1.21 mi Storm Q2 94.3 cfs 122(A)0.635 81.4 cfs Q10 276.8 cfs 335(A)0.596 229.0 cfs Q25 423.5 cfs 504(A)0.581 347.9 cfs Q50 560.0 cfs 661(A)0.570 459.4 cfs Q100 711.9 cfs 849(A)0.559 594.3 cfs Culvert G 251.2 Ac 927.5 ft 6080 ft 0.393 sq mi 1.15 mi Storm Q2 74.2 cfs 122(A)0.635 67.4 cfs Q10 220.1 cfs 335(A)0.596 191.9 cfs Q25 337.0 cfs 504(A)0.581 292.7 cfs Q50 445.3 cfs 661(A)0.570 387.9 cfs Q100 565.6 cfs 849(A)0.559 503.4 cfs 21.6A0.881E0.310L-0.423 38.8A0.848E0.379L-0.430 54.8A0.852E0.392L-0.463 74.3A0.860E0.390L-0.495 101A0.869E0.382L-0.529 A E L Southern Piedmont Regression Equations Multiple-Parameter Drainage-Area-Only 21.6A0.881E0.310L-0.423 38.8A0.848E0.379L-0.430 54.8A0.852E0.392L-0.463 74.3A0.860E0.390L-0.495 101A0.869E0.382L-0.529 A E L Southern Piedmont Regression Equations Multiple-Parameter Drainage-Area-Only A E L Multiple-Parameter Drainage-Area-Only Southern Piedmont Regression Equations 21.6A0.881E0.310L-0.423 38.8A0.848E0.379L-0.430 54.8A0.852E0.392L-0.463 74.3A0.860E0.390L-0.495 101A0.869E0.382L-0.529 93 1.301.34NOTE: FOR CULVERTS A, B, & G, RUNOFF FLOW "Q"RESULTS FROM SOUTHERN PEIDMONT RURALREGRESSION EQUATION -- DRAINAGE AREA ONLY.SINCE TWO (2) CULVERTS WILL BE USED, TOTALFLOW IS DIVIDED IN HALF FOR THIS NOMOGRAPH.1.421.50 94 Structure NumberInlet TypeCurb OpeningCatchment AreaRunoff CoefCAIntensityQ CatchmentQ carryoverQ TotalMannings NGutter SlopePave X-slopeGutter X-slopeTotal Gutter SpreadDepth at Curb% EfficencyQ interceptedQ BypassedMidpoint DepthCurb HeightD/HMidpoint Spread12 3 4 5 6 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24(ft) (ac)(in/hr) (cfs) (cfs) (cfs)('/') ('/') ('/') (ft) (ft)(cfs) (cfs) (ft) (ft)(ft)F4 DI-3B 12 0.43 0.67 0.29 4.0 1.141.140.015 0.040 0.020 0.0833.380.19 100.0%1.140.006.5 1.861.865.000.23100.0%1.860.00F3 DI-3B 10 0.63 0.60 0.38 4.0 1.511.510.015 0.025 0.020 0.0835.620.24 100.0%1.510.006.5 2.452.457.420.28100.0%2.450.00F2 DI-7* 4x4 28.67 0.34 9.85 4.0 39.39 0.0039.390.025 0.050 0.150 -1.29 1 1.297.096.5 64.00 0.0064.001.781 1.78 8.51E9 DI-7* 4x4 10.75 0.47 5.05 4.0 20.1920.190.025 0.100 0.120 -0.82 1.5 0.558.876.5 32.8032.801.141.5 0.76 11.49E8A DI-3B 12 0.47 0.72 0.34 4.0 1.35 0.001.350.015 0.065 0.040 0.0833.120.19 100.0%1.350.006.5 2.20 0.002.204.740.2396.7%2.130.07E8 DI-3C 14 0.92 0.59 0.54 4.0 2.16 0.002.160.015 0.065 0.020 0.0834.680.22 100.0%2.160.006.5 3.51 0.003.516.390.2592.4%3.240.27E7C 36" ES-1 - 39.08 0.22 8.60 4.0 34.39 0.0034.390.025 0.150 0.042 0.0830.61 4 0.1512.16Note: Culvert HW/D = 1.5 for Q=55.89. Inlet is satisfactory. 6.5 55.8955.890.854 0.21 14.58E7A DI-3B 10 0.25 0.71 0.18 4.0 0.70 0.000.700.015 0.092 0.020 0.0831.670.16 100.0%0.700.006.5 1.14 0.071.212.200.1797.2%1.180.03E7 DI-3B 12 0.46 0.60 0.27 4.0 1.10 0.001.100.015 0.092 0.020 0.0831.980.17 100.0%1.100.006.5 1.79 0.272.055.320.2095.0%1.950.10E6A DI-3C 10 0.41 0.72 0.29 4.0 1.17 0.001.170.015 0.030 0.020 0.0833.920.20 100.0%1.170.006.5 1.91 0.031.945.650.2498.6%1.920.03E6 DI-3B 12 0.68 0.55 0.37 4.0 1.49 0.001.490.015 0.030 0.020 0.0834.730.22 100.0%1.490.006.5 2.41 0.102.526.590.2399.3%2.500.02E5 DI-3C 10 1.27 0.59 0.74 4.0 2.97 0.002.970.015 0.012 0.020 0.0830.21 0.5 0.424.116.5 4.82 0.024.840.290.5 0.58 8.11E4 DI-3B 8 0.15 0.78 0.11 4.0 0.46 0.000.460.015 0.022 0.020 0.0831.860.16 100.0%0.460.006.5 0.74 0.020.763.010.19100.0%0.760.00E3 DI-3C 8 0.41 0.72 0.29 4.0 1.18 0.001.180.015 0.022 0.020 0.0834.630.22 100.0%1.180.006.5 1.91 0.001.916.320.2594.6%1.810.10E2 DI-3B 10 0.60 0.69 0.41 4.0 1.64 0.001.640.015 0.020 0.020 0.0830.24 0.5 0.485.776.5 2.66 0.102.770.280.5 0.56 7.73D3 DI-3C 8 1.19 0.51 0.61 4.0 2.44 0.002.440.015 0.010 0.020 0.0830.30 0.5 0.608.636.5 3.97 0.003.970.340.5 0.69 10.82D2 DI-3B 12 0.52 0.54 0.28 4.0 1.111.110.015 0.020 0.020 0.0832.620.18 100.0%1.110.006.5 1.801.804.200.21100.0%1.800.00C3 DI-3C 6 0.29 0.82 0.24 4.0 0.950.950.015 0.006 0.020 0.0830.25 0.5 0.495.976.5 1.551.550.280.5 0.57 7.82C2 DI-3C 6 0.14 0.85 0.12 4.0 0.47 0.000.470.015 0.020 0.020 0.0830.21 0.5 0.423.966.5 0.77 0.000.770.240.5 0.48 5.66*Assumes 25% cloggingLD-204 Stormwater Inlet ComputationsInlets on Grade OnlySag Inlets OnlyGalaxie Farm 95 From To Catch. Runoff Increment Accum. Total Total Total Up Down Pipe Invert Pipe Pipe Velocity Flow timeStructure Structure Area Coef AC AC TOC Intensity Flow Invert Invert Length Slope Diameter CapacityIncrement(ac)(min) (in/hr) (cfs) Elev. Elev. (ft) % (in) (cfs) (ft/s) (min)1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 1617G2 G1 251.22 0.42 105.51 105.51 67.3 1.88198.08467.50 466.50 45.00 2.22% (2) 48146.411.6F4 F3 0.43 0.67 0.29 0.29 5.00 6.811.95480.00 479.00 149.64 0.67% 155.74.2 0.59F3 F2 0.63 0.60 0.38 0.66 5.59 6.644.40478.80 478.50 39.07 0.77% 156.15.4 0.12F2 F1 28.67 0.34 9.85 10.51 23.50 3.8340.21478.30 476.00 114.73 2.00% 2434.711.0 0.17E9 E8 10.75 0.47 5.05 5.05 23.25 3.8519.43516.00 505.70 250.92 4.10% 1823.014.6 0.29E8A E8 0.47 0.72 0.34 0.34 5.00 6.812.30506.00 505.70 28.02 1.07% 157.35.2 0.09E8 E7 0.92 0.59 0.54 5.92 23.53 3.8222.65505.50 492.00 161.72 8.35% 1832.920.0 0.13E7C E7B 39.08 0.22 8.60 8.60 29.02 3.3829.09486.00 485.90 5.00 2.00% 36102.215.3 0.01E7B E7A 0.00 0.00 0.00 8.60 29.03 3.3829.09485.70 484.70 86.98 1.15% 3677.512.4 0.12E7A E7 0.25 0.71 0.18 8.77 29.03 3.3829.68484.50 484.20 27.52 1.09% 3675.412.1 0.04E7 E6 0.46 0.60 0.27 14.97 29.16 3.3750.52484.00 476.50 256.02 2.93% 36123.719.3 0.22E6Z E6* *10 yr Flow from HydroCAD model35.72476.00 475.20 16.12 4.96% 36160.918.3 0.01E6A E6 0.41 0.72 0.29 0.29 5.00 6.812.00477.70 477.00 30.08 2.33% 1510.76.7 0.08E6 E5 0.68 0.55 0.37 15.64 29.39 3.3688.24475.00 471.40 195.55 1.84% 3698.013.9 0.23E5 E4 1.27 0.59 0.74 16.38 29.62 3.3490.46471.20 470.60 59.92 1.00% 3672.310.2 0.10E4 E3 0.15 0.78 0.11 16.49 29.72 3.3490.74470.40 470.10 28.87 1.04% 3673.710.4 0.05E3 E2 0.41 0.72 0.29 16.79 29.76 3.3391.66469.90 469.00 74.82 1.20% 3679.211.2 0.11E2 E1 0.60 0.69 0.41 17.20 29.88 3.3292.90468.80 466.80 149.78 1.34% 3683.611.8 0.21D3 D2 1.19 0.51 0.61 0.61 5.00 6.814.16469.00 468.20 61.011.31%158.06.6 0.15D2 D1 0.52 0.60 0.31 0.92 5.15 6.776.22468.00 465.00 76.403.93%1513.911.0 0.12C3 C2 0.29 0.82 0.24 0.24 5.00 6.811.62463.00 462.70 31.950.94%156.84.5 0.12C2 C1 0.14 0.85 0.12 0.36 5.12 6.782.41462.50 462.00 8.046.22%1517.510.0 0.01B2 B1 338.08 0.43 144.02 144.02 67.6 1.87269.63462.70 460.50 64.003.44%(2) 6018.7330.5A2 A1 133.20 0.42 55.94 55.94 45.5 2.52140.70464.30 460.50 71.305.33%(2) 4819.0226.3LD-229 Storm Drain Design ComputationsGalaxie Farm 96 Earthn=.03INCR ACCVel.* Qn Velocity* Depth** Qn Depth1 0.45 3.67 1.63 1.63 16.5 3 3 0.012 0.080 2-Yr 3.31 5.41 6.00.275.000.96 10-Yr 4.59 7.490.375.431.09*Velocity calculations performed using maximum slope for this application**Depth calculations performed using minimum slope for this applicationQ (cfs)Allowable Velocity (fps)EC-2 or EC-3: n=.05 Paved: n=.015CATOC _:1 L _:1 RDesign StormIntensity (in/hr)Galaxie Farm Modified LD-268 Roadside and Median Ditch Design FormSide SlopeMin Slope (ft/ft)Max Slope (ft/ft)Protective LiningDitch C A 97 GALAXIE FARM OUTLET PROTECTION NOMOGRAPH GREEN BOOK FIG. 3.18-3 98 GALAXIE FARM Orange cells need input, white cells are calculations. Basin Step 1: Preliminary Design Top of Dam Downstream Toe of Dam Barrel length (ft) Slope of principal spillway barrel (%) Step 2: Calculate Runoff Rational Method Drainage Area (ac) C I2 I25 Q2 (cfs) Q25 (cfs) Step 3: Principal Spillway From Plate 3.14-8 Spillway Capacity with emergency spillway (cfs) Riser Diameter (in) Actual head (ft) Qp (max) Step 4: Emergency Spillway From Table 3.14-C Required spillway capacity Hp b - Bottom width (ft) S - slope of exit channel (ft/foot) X - minimum length of exit channel (ft) Step 5: Grade Basin Design Parameters Maximum Top of wet Storage Required Wet + Dry Storage (cy) Wet Storage Required Volume (cy) Required Volume (cf) Minimum Standpipe Invert Cleanout Required Volume (cy) Cleanout Max. Volume (cf) Design Elevation Area (sf) Bottom of Wet Storage 470.0 3,600 SB-1 478.0 472.0 90.0 475.0 965 1.00 40.0 7.20 0.8 4.3 6.6 2.5% 23.2 35.6 35.6 48 6,415 0.0 0.0 0 0.00 0 482 13,025 472.0 238 99 Basin SB-1 471.0 4,096 Cleanout Elevation 471.5 4,356 472.5 4,900 Top of Wet Storage 473.0 5,184 Cleanout Volume (cf) Wet Storage Volume (cf) Wet Storage Volume (cy) Dry Storage Required Volume (cy) Required Volume (cf) Maximum Top of Dry Storage Design Elevation Area (sf) Bottom of Dry Storage 473.0 5,184 474.0 6,536 Top of Dry Storage 475.0 8,000 Dry Storage Volume (cf) Dry Storage Volume (cy) 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) Qp (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) Baffle Calculation Length of Flow (L) (ft) Effective Width (We) (ft) L/We Baffles Required? 24 5,961 13,110 486 13,025 476.0 13,128 482 486 470.0 475.0 72 0.126 1.0 yes 21 5.0 39.0 30 5.0 0.401 6 8 30 1.0 13,128 0.61 100 101 102 103 104 105 106 107 Hydrologic Soil Group—Albemarle County, Virginia (Cow Branch Drainage Area) Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 5/5/2020 Page 1 of 5420620042066004207000420740042078004208200420860042062004206600420700042074004207800420820042086004209000717800718200718600719000719400719800720200720600721000721400721800722200 717800 718200 718600 719000 719400 719800 720200 720600 721000 721400 721800 722200 38° 0' 6'' N 78° 31' 19'' W38° 0' 6'' N78° 28' 4'' W37° 58' 33'' N 78° 31' 19'' W37° 58' 33'' N 78° 28' 4'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 17N WGS84 0 250 500 1000 1500 Feet 0 50 100 200 300 Meters Map Scale: 1:5,940 if printed on D landscape (34" x 22") sheet. Soil Map may not be valid at this scale. 108 MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Rating Polygons A A/D B B/D C C/D D Not rated or not available Soil Rating Lines A A/D B B/D C C/D D Not rated or not available Soil Rating Points A A/D B B/D C C/D D Not rated or not available Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography 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. Hydrologic Soil Group—Albemarle County, Virginia (Cow Branch Drainage Area) Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 5/5/2020 Page 2 of 5 109 Hydrologic Soil Group Map unit symbol Map unit name Rating Acres in AOI Percent of AOI 13C Catoctin silt loam, 7 to 15 percent slopes, very stony B 4.4 0.5% 13E Catoctin silt loam, 25 to 45 percent slopes, very stony B 66.0 8.0% 25B Dyke silt loam, 2 to 7 percent slopes B 11.4 1.4% 26C3 Dyke clay loam, 7 to 15 percent slopes, severely eroded B 5.7 0.7% 39C Hazel loam, 7 to 15 percent slopes B 0.5 0.1% 40D Hazel loam, 15 to 25 percent slopes, very stony B 1.0 0.1% 58B Myersville silt loam, 2 to 7 percent slopes B 18.8 2.3% 58C Myersville silt loam, 7 to 15 percent slopes B 46.8 5.7% 58D Myersville silt loam, 15 to 25 percent slopes B 26.2 3.2% 59C Myersville very stony silt loam, 7 to 15 percent slopes B 29.7 3.6% 59D Myersville very stony silt loam, 15 to 25 percent slopes B 34.7 4.2% 59E Myersville very stony silt loam, 25 to 45 percent slopes B 91.8 11.1% 63B Orange silt loam, 2 to 7 percent slopes C/D 11.8 1.4% 69 Pits, quarry 3.3 0.4% 71B Rabun clay loam, 2 to 7 percent slopes B 66.8 8.1% 71C Rabun clay loam, 7 to 15 percent slopes B 35.2 4.3% 71D Rabun clay loam, 15 to 25 percent slopes B 15.8 1.9% 72B3 Rabun clay, 2 to 7 percent slopes, severely eroded B 9.7 1.2% Hydrologic Soil Group—Albemarle County, Virginia Cow Branch Drainage Area Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 5/5/2020 Page 3 of 5 110 Map unit symbol Map unit name Rating Acres in AOI Percent of AOI 72C3 Rabun clay, 7 to 15 percent slopes, severely eroded B 108.3 13.1% 72D3 Rabun clay, 15 to 25 percent slopes, severely eroded B 78.4 9.5% 72E3 Rabun clay, 25 to 45 percent slopes, severely eroded B 20.0 2.4% 73D Rabun clay loam, 15 to 25 percent slopes, very stony B 5.0 0.6% 73E Rabun clay loam, 25 to 45 percent slopes, very stony B 58.8 7.1% 76 Dan River loam, 0 to 2 percent slopes, occasionally flooded B 3.4 0.4% 79B Meadowville silt loam, 2 to 7 percent slopes B 50.6 6.1% 88 Udorthents, loamy, 2 to 25 percent slopes 16.3 2.0% 90C Unison very stony silt loam, 7 to 15 percent slopes B 7.5 0.9% Totals for Area of Interest 827.9 100.0% Hydrologic Soil Group—Albemarle County, Virginia Cow Branch Drainage Area Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 5/5/2020 Page 4 of 5 111 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. Rating Options Aggregation Method: Dominant Condition Component Percent Cutoff: None Specified Tie-break Rule: Higher Hydrologic Soil Group—Albemarle County, Virginia Cow Branch Drainage Area Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 5/5/2020 Page 5 of 5 112 NOAA Atlas 14, Volume 2, Version 3 Location name: Charlottesville, Virginia, USA* Latitude: 37.9931°, Longitude: -78.4956° Elevation: 481.02 ft** * source: ESRI Maps ** source: USGS POINT PRECIPITATION FREQUENCY ESTIMATES G.M. Bonnin, D. Martin, B. Lin, T. Parzybok, M.Yekta, and D. Riley NOAA, National Weather Service, Silver Spring, Maryland PF_tabular | PF_graphical | Maps_&_aerials PF tabular PDS-based point precipitation frequency estimates with 90% confidence intervals (in inches)1 Duration Average recurrence interval (years) 1 2 5 10 25 50 100 200 500 1000 5-min 0.352 (0.317‑0.391) 0.418 (0.377‑0.465) 0.489 (0.440‑0.543) 0.551 (0.495‑0.610) 0.620 (0.554‑0.685) 0.674 (0.600‑0.743) 0.723 (0.641‑0.797) 0.770 (0.677‑0.849) 0.825 (0.718‑0.912) 0.870 (0.751‑0.964) 10-min 0.562 (0.506‑0.625) 0.669 (0.603‑0.743) 0.784 (0.705‑0.869) 0.881 (0.791‑0.976) 0.988 (0.884‑1.09) 1.07 (0.956‑1.18) 1.15 (1.02‑1.27) 1.22 (1.07‑1.35) 1.31 (1.14‑1.44) 1.37 (1.18‑1.52) 15-min 0.703 (0.632‑0.781) 0.841 (0.758‑0.934) 0.991 (0.892‑1.10) 1.11 (1.00‑1.23) 1.25 (1.12‑1.38) 1.36 (1.21‑1.50) 1.45 (1.29‑1.60) 1.54 (1.36‑1.70) 1.64 (1.43‑1.82) 1.72 (1.48‑1.91) 30-min 0.963 (0.867‑1.07) 1.16 (1.05‑1.29) 1.41 (1.27‑1.56) 1.61 (1.45‑1.79) 1.86 (1.66‑2.05) 2.05 (1.82‑2.26) 2.23 (1.97‑2.45) 2.40 (2.11‑2.64) 2.61 (2.28‑2.89) 2.78 (2.40‑3.09) 60-min 1.20 (1.08‑1.34) 1.46 (1.31‑1.62) 1.81 (1.63‑2.00) 2.10 (1.89‑2.33) 2.47 (2.21‑2.73) 2.77 (2.47‑3.06) 3.07 (2.71‑3.38) 3.36 (2.96‑3.71) 3.75 (3.27‑4.14) 4.06 (3.51‑4.51) 2-hr 1.44 (1.27‑1.65) 1.75 (1.53‑1.99) 2.18 (1.92‑2.49) 2.57 (2.25‑2.91) 3.06 (2.66‑3.46) 3.46 (3.00‑3.92) 3.88 (3.35‑4.39) 4.31 (3.69‑4.87) 4.91 (4.15‑5.55) 5.40 (4.53‑6.13) 3-hr 1.58 (1.38‑1.82) 1.91 (1.67‑2.19) 2.38 (2.08‑2.74) 2.80 (2.44‑3.21) 3.34 (2.89‑3.81) 3.79 (3.27‑4.32) 4.25 (3.64‑4.84) 4.72 (4.02‑5.39) 5.37 (4.51‑6.14) 5.93 (4.93‑6.77) 6-hr 2.02 (1.78‑2.29) 2.43 (2.15‑2.76) 3.02 (2.65‑3.42) 3.56 (3.12‑4.02) 4.27 (3.72‑4.82) 4.90 (4.24‑5.51) 5.55 (4.76‑6.25) 6.26 (5.31‑7.05) 7.25 (6.06‑8.17) 8.12 (6.70‑9.16) 12-hr 2.54 (2.24‑2.91) 3.06 (2.70‑3.50) 3.81 (3.35‑4.35) 4.51 (3.95‑5.15) 5.49 (4.77‑6.24) 6.36 (5.47‑7.22) 7.30 (6.20‑8.27) 8.33 (6.98‑9.43) 9.84 (8.09‑11.2) 11.2 (9.07‑12.7) 24-hr 3.04 (2.73‑3.41) 3.67 (3.30‑4.12) 4.70 (4.21‑5.27) 5.55 (4.96‑6.21) 6.83 (6.06‑7.60) 7.92 (6.98‑8.80) 9.13 (7.97‑10.1) 10.5 (9.04‑11.6) 12.5 (10.6‑13.8) 14.2 (11.9‑15.7) 2-day 3.58 (3.21‑4.00) 4.34 (3.89‑4.85) 5.52 (4.94‑6.16) 6.49 (5.79‑7.24) 7.90 (7.00‑8.79) 9.09 (8.00‑10.1) 10.4 (9.06‑11.5) 11.8 (10.2‑13.1) 13.8 (11.8‑15.4) 15.5 (13.1‑17.3) 3-day 3.81 (3.46‑4.22) 4.62 (4.19‑5.11) 5.87 (5.32‑6.49) 6.90 (6.23‑7.62) 8.39 (7.53‑9.26) 9.64 (8.60‑10.6) 11.0 (9.74‑12.1) 12.5 (11.0‑13.8) 14.6 (12.7‑16.2) 16.4 (14.1‑18.2) 4-day 4.04 (3.71‑4.44) 4.89 (4.49‑5.37) 6.22 (5.69‑6.82) 7.30 (6.67‑8.00) 8.88 (8.07‑9.72) 10.2 (9.21‑11.2) 11.6 (10.4‑12.7) 13.2 (11.7‑14.4) 15.4 (13.6‑16.9) 17.3 (15.1‑19.1) 7-day 4.69 (4.32‑5.11) 5.65 (5.20‑6.15) 7.06 (6.49‑7.69) 8.23 (7.54‑8.95) 9.89 (9.02‑10.8) 11.3 (10.2‑12.3) 12.8 (11.5‑13.9) 14.4 (12.8‑15.7) 16.7 (14.7‑18.2) 18.6 (16.2‑20.4) 10-day 5.32 (4.92‑5.74) 6.38 (5.91‑6.90) 7.88 (7.28‑8.51) 9.10 (8.39‑9.82) 10.8 (9.93‑11.7) 12.2 (11.2‑13.2) 13.7 (12.5‑14.8) 15.3 (13.8‑16.5) 17.5 (15.6‑19.0) 19.4 (17.1‑21.1) 20-day 6.98 (6.55‑7.47) 8.33 (7.81‑8.91) 10.1 (9.43‑10.8) 11.4 (10.7‑12.2) 13.3 (12.4‑14.2) 14.7 (13.7‑15.7) 16.2 (15.0‑17.4) 17.7 (16.3‑19.0) 19.8 (18.1‑21.3) 21.4 (19.4‑23.1) 30-day 8.57 (8.07‑9.12) 10.2 (9.57‑10.8) 12.0 (11.3‑12.8) 13.4 (12.6‑14.3) 15.3 (14.3‑16.2) 16.7 (15.6‑17.7) 18.1 (16.8‑19.2) 19.4 (18.0‑20.7) 21.2 (19.6‑22.6) 22.5 (20.7‑24.1) 45-day 10.7 (10.1‑11.3) 12.6 (11.9‑13.4) 14.8 (14.0‑15.6) 16.4 (15.5‑17.3) 18.4 (17.4‑19.5) 19.9 (18.8‑21.1) 21.4 (20.1‑22.7) 22.8 (21.3‑24.2) 24.7 (22.9‑26.2) 26.0 (24.1‑27.7) 60-day 12.6 (11.9‑13.3) 14.8 (14.0‑15.6) 17.1 (16.2‑18.0) 18.8 (17.8‑19.8) 21.0 (19.8‑22.1) 22.6 (21.3‑23.8) 24.1 (22.7‑25.4) 25.5 (24.0‑27.0) 27.4 (25.6‑29.0) 28.7 (26.8‑30.5) 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 PF graphical Precipitation Frequency Data Server https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=37.9931&... 1 of 4 5/5/2020, 9:59 AM 113 Back to Top Maps & aerials Small scale terrain Precipitation Frequency Data Server https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=37.9931&... 2 of 4 5/5/2020, 9:59 AM 114 Large scale terrain Large scale map Large scale aerial + – 3km 2mi + – 100km 60mi + – 100km 60mi Precipitation Frequency Data Server https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=37.9931&... 3 of 4 5/5/2020, 9:59 AM 115