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HomeMy WebLinkAboutWPO201700019 Plan - Stormwater WPO VSMP 2018-05-03 Scottsville Elementary School Security Addition ALBEMARLE COUNTY, VIRGINIA MINOR SITE PLAN AMENDMENT DESIGN CALCULATIONS & NARRATIVE FEBRUARY 21, 2017 REVISED APRIL 3, 2017 REVISED JULY 13, 2017 REVISED AUGUST 1, 2017 REVISED MARCH 30, 2018 REVISED MAY 3, 2018 TIMMONS GROUP YOUR VISION ACHIEVED THROUGH OURS. Prepared by: Craig Kotarski, PE Timmons Group 608 Preston Avenue, Suite 200 Charlottesville, VA 22903 434.327.1688 74 CA6 61 0 CRAIG W J. KOTTARSKI Lie.Na.0402048507 135I3f)S (Sc Table of Contents Section Title 1 Project Narrative 2 Outlet Protection Sizing 3 Stormwater Quantity Calculations 4 Pre-Developed HydroCAD Calculations 5 Post-Developed HydroCAD Calculations 6 Virginia Runoff Reduction Method ReDevelopment Worksheet Project Narrative: This project includes a building addition to Scottsville Elementary School, an update bus loop, additional parking, sidewalk and associated site work. Limits of disturbance is 0.61 acres. Water Quality: Currently there exists 0.46 acres of managed turf and 0.15 acres of impervious cover within the site limits. In the proposed condition, there will be 0.34 acres of managed turf and 0.27 acres of impervious cover. Per the Virginia Runoff Reduction Redevelopment Spreadsheet, this will require that 0.26 lb/yr to be removed. This required reduction is being met through a surplus removal of 0.41 lb/yr that has been achieved on the Woodbrook Elementary School project. See Plan WPO201600074. This surplus removal will be applied to this project, as ownership for both parcels is the same, the Albemarle County School Board, per 9VAC25-870-69 Section A Part 5. Water Quantity: Water quantity is addressed through modification of the existing stormwater management facility. The facility will be excavated deeper and slightly wider and the outfall structure will be modified. The modified facility will detain and release stormwater at the appropriate rate for channel and flood protection requirements. Channel Protection (Energy Balance): The Energy Balance Equation has been applied to the 1 year storm for the 3.55 acre drainage area to the existing pond. 0.8 * (QPRE—DEVELOPED * RVPRE—DEVELOPED QDeveloped — ) I RVPOST—DEVELOPED 3.74 cfs < 0.8 * ((5.03)cfs * (0.381)acft) — 3.83c s /(0.400ac f t) — f Q Developed is 3.74 CFS which is less than the 3.83 CFS satisfying the Energy Balance Equation. Flood Protection (10 year storm): Post-Developed Qio< Pre-Developed Q10 12.28cfs < 13.07cfs 1992 3.18 w 0 _0 laai 1a4s deadi11 05p "Co ct M N .--t O O Milk='_=.=3== -= j' - i — i •° :iy�' .` -:-Ki,-� �._- =ANT_ w''^_�� • EMI - :, T c -%n. z = _per--Iii � s IO ` � _ y , ------ - _ . , ' ~3 as a`a _ �. `Z. it � S: 0. - - t- ---• : - ,.N.vitii: I§ : - . OJ • ` . . : • : -I ..-', !to. ME-::-.17:-: -..1 43. ''.: : : . :. 0 .. I 1 - *INAll " f' 1 ' „a, CO CD `"`1aass ".: E "..', aa, Iin _ * ; -- � 61 Milli it I��d _ iiiiiMilail-- 0%, -\ 1 . G. do- CC I W W Q.-t-.._ • CL.F- O to•1 • N I v1a yas=� � ORM*d Vz o o Oiir� ` T re • o o + ,i, a�iRs °a ii ce V -Iv 3�� - ill- i�ii�iwiG �iiia: ca!/ac=za:�s///!�l�sR/RRR_�lan _ almaimii]i��i/ii iii i �. N/ j Mi ' mut iu' me'im.- y• _ to W 0O O 5...1 -iiiGiaiimoms In% _ a. cx iii//slit 0 / --.-- W F- RlRR/■i'�■1i//SC/l11.�■ a- _ _ M O.J. i- 0 0 0 __.. - C~ ) e t �� drt II G GO Z O d 0 n , Q E p0 N '� of v T+ b c^ 141Qo rJ EEv U II (, I t E : el 0 II 3 3 3 2 3 ab Source: USDA-SCS Plate 3.18-3 III - 164 Ex. SW Facility Draina a Area AND EX. SWM Facility SUbcat Reach 'On• Routing Diagram for Pre-Developed Prepared by Timmons Group, Printed 8/2/2017 HydroCAD®10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Pre-Developed Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 2 Area Listing (all nodes) Area CN Description (acres) (subcatchment-numbers) 2.320 74 >75% Grass cover, Good, HSG C (2S) 1.230 98 Paved parking, HSG C (2S) 3.550 82 TOTAL AREA Pre-Developed Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 3 Pipe Listing (all nodes) Line# Node In-Invert Out-Invert Length Slope n Diam/Width Height Inside-Fill Number (feet) (feet) (feet) (ft/ft) (inches) (inches) (inches) 1 3P 389.91 389.62 53.0 0.0055 0.011 24.0 0.0 0.0 Pre-Developed Type 1124-hr 1 YR Rainfall=3.04" Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 4 Summary for Subcatchment 2S: Ex. SWM Facility Drainage Area Runoff = 5.30 cfs @ 12.15 hrs, Volume= 0.381 af, Depth> 1.29" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 3.00-20.01 hrs, dt= 0.03 hrs Type II 24-hr 1 YR Rainfall=3.04" Area (ac) CN Description 1.230 98 Paved parking, HSG C 2.320 74 >75% Grass cover, Good, HSG C 3.550 82 Weighted Average 2.320 65.35% Pervious Area 1.230 34.65% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 19.7 200 0.0300 0.17 Sheet Flow, Grass: Dense n= 0.240 P2= 3.68" 1.8 150 0.0400 1.40 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 21.5 350 Total Subcatchment 2S: Ex. SWM Facility Drainage Area / Hydrograph Runoff I5.3Ods I 5- Type II 24-hr 1 YR Rainfall_3.04" 4- Runoff Area=3.550 ac Runoff Volume-0.381 af fl 3- Runoff Depth>1.29" LL _ Flow Length=350' 2- Tc=21.5 min CN=82 o 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Pre-Developed Type 1124-hr 1 YR Rainfall=3.04" Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 5 Hydrograph for Subcatchment 2S: Ex. SWM Facility Drainage Area Time Precip. Excess Runoff Time Precip. Excess Runoff (hours) (inches) (inches) (cfs) (hours) (inches) (inches) (cfs) 3.00 0.10 0.00 0.00 18.60 2.83 1.25 0.15 3.30 0.12 0.00 0.00 18.90 2.85 1.26 0.14 3.60 0.13 0.00 0.00 19.20 2.86 1.27 0.13 3.90 0.14 0.00 0.00 19.50 2.87 1.28 0.13 4.20 0.15 0.00 0.00 19.80 2.89 1.29 0.12 4.50 0.17 0.00 0.00 4.80 0.18 0.00 0.00 5.10 0.20 0.00 0.00 5.40 0.21 0.00 0.00 5.70 0.23 0.00 0.00 6.00 0.24 0.00 0.00 6.30 0.26 0.00 0.00 6.60 0.28 0.00 0.00 6.90 0.29 0.00 0.00 7.20 0.31 0.00 0.00 7.50 0.33 0.00 0.00 7.80 0.35 0.00 0.00 8.10 0.37 0.00 0.00 8.40 0.39 0.00 0.00 8.70 0.42 0.00 0.00 9.00 0.45 0.00 0.00 9.30 0.48 0.00 0.00 9.60 0.51 0.00 0.01 9.90 0.54 0.00 0.02 10.20 0.58 0.01 0.03 10.50 0.62 0.01 0.05 10.80 0.67 0.02 0.08 11.10 0.74 0.04 0.12 11.40 0.83 0.06 0.20 11.70 1.08 0.14 0.40 12.00 2.02 0.66 3.21 12.30 2.17 0.76 3.64 12.60 2.26 0.83 1.31 12.90 2.33 0.87 0.72 13.20 2.38 0.91 0.53 13.50 2.43 0.95 0.44 13.80 2.47 0.98 0.38 14.10 2.50 1.00 0.33 14.40 2.54 1.02 0.30 14.70 2.57 1.05 0.28 15.00 2.59 1.07 0.26 15.30 2.62 1.09 0.25 15.60 2.65 1.11 0.23 15.90 2.67 1.12 0.21 16.20 2.69 1.14 0.20 16.50 2.71 1.15 0.19 16.80 2.73 1.17 0.18 17.10 2.75 1.18 0.17 17.40 2.77 1.20 0.17 17.70 2.78 1.21 0.16 18.00 2.80 1.22 0.16 18.30 2.82 1.24 0.15 Pre-Developed Type 1124-hr 1 YR Rainfall-3.04" Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 6 Summary for Pond 3P: EX. SWM Facility Inflow Area = 3.550 ac, 34.65% Impervious, Inflow Depth > 1.29" for 1 YR event Inflow = 5.30 cfs @ 12.15 hrs, Volume= 0.381 of Outflow = 5.03 cfs @ 12.20 hrs, Volume= 0.364 af, Atten= 5%, Lag= 3.0 min Primary = 5.03 cfs @ 12.20 hrs, Volume= 0.364 af Routing by Stor-Ind method, Time Span= 3.00-20.01 hrs, dt= 0.03 hrs/3 Peak Elev= 393.59' @ 12.20 hrs Surf.Area= 3,970 sf Storage= 1,799 cf Plug-Flow detention time= 25.4 min calculated for 0.364 of (96% of inflow) Center-of-Mass det. time= 9.8 min ( 813.7 - 803.8 ) Volume Invert Avail.Storage Storage Description #1 393.00' 4,931 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 393.00 1,900 0 0 393.50 3,839 1,435 1,435 394.00 4,540 2,095 3,530 394.30 4,800 1,401 4,931 Device Routing Invert Outlet Devices #1 Primary 389.91' 24.0" Round Culvert L= 53.0' RCP, square edge headwall, Ke= 0.500 Inlet/Outlet Invert= 389.91'/389.62' S= 0.0055 '/' Cc= 0.900 n= 0.011 Concrete pipe, straight & clean, Flow Area= 3.14 sf #2 Device 1 393.26' 24.0"x 24.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=5.01 cfs @ 12.20 hrs HW=393.59' (Free Discharge) t-1=Culvert (Passes 5.01 cfs of 24.77 cfs potential flow) t-2=Orifice/Grate (Weir Controls 5.01 cfs @ 1.89 fps) Pre-Developed Type 1124-hr 1 YR Rainfall=3.04" Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 7 Pond 3P: EX. SWM Facility Hydrograph �■Inflow ®Primary Inflow Area=3.550 a 1 am 5 !' Peak Elev=393.59' 4 Storage=1 ,799 cf 3 0 LL fel 2 1 e ti 0 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Pond 3P: EX. SWM Facility Stage-Discharge z ■Primary 394- . g W Ofte/Grate 393 , . . , . 0 2 4 6 8 10 12 14 16' 18 Discharge (cfs) Pre-Developed Type l/24-hr 1 YR Rainfall=3.04" Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 8 Pond 3P: EX. SWM Facility Stage-Area-Storage Surface HorizontalWetted Area(sq-ft) 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500 0 Surface 1 �Storage 394- d c 0 o w 393 / 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500 Storage(cubic-feet) Pre-Developed Type 1124-hr 1 YR Rainfall=3.04" Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 9 Hydrograph for Pond 3P: EX. SWM Facility Time Inflow Storage Elevation Primary (hours) (cfs) (cubic-feet) (feet) (cfs) 3.00 0.00 0 393.00 0.00 3.60 0.00 0 393.00 0.00 4.20 0.00 0 393.00 0.00 4.80 0.00 0 393.00 0.00 5.40 0.00 0 393.00 0.00 6.00 0.00 0 393.00 0.00 6.60 0.00 0 393.00 0.00 7.20 0.00 0 393.00 0.00 7.80 0.00 0 393.00 0.00 8.40 0.00 0 393.00 0.00 9.00 0.00 0 393.00 0.00 9.60 0.01 8 393.00 0.00 10.20 0.03 54 393.03 0.00 10.80 0.08 173 393.08 0.00 11.40 0.20 452 393.20 0.00 12.00 3.21 1,260 393.45 2.22 12.60 1.31 1,122 393.41 1.60 13.20 0.53 864 393.34 0.57 13.80 0.38 811 393.32 0.40 14.40 0.30 780 393.31 0.31 15.00 0.26 765 393.31 0.27 15.60 0.23 754 393.30 0.23 16.20 0.20 742 393.30 0.20 16.80 0.18 733 393.30 0.18 17.40 0.17 728 393.29 0.17 18.00 0.16 723 393.29 0.16 18.60 0.15 718 393.29 0.15 19.20 0.13 713 393.29 0.14 19.80 0.12 708 393.29 0.12 Pre-Developed Type 1124-hr 1 YR Rainfall=3.04" Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 10 Stage-Discharge for Pond 3P: EX. SWM Facility Elevation Primary Elevation Primary Elevation Primary (feet) (cfs) (feet) (cfs) (feet) (cfs) 393.00 0.00 393.52 3.47 394.04 17.01 393.01 0.00 393.53 3.67 394.05 17.12 393.02 0.00 393.54 3.88 394.06 17.23 393.03 0.00 393.55 4.09 394.07 17.33 393.04 0.00 393.56 4.30 394.08 17.44 393.05 0.00 393.57 4.52 394.09 17.55 393.06 0.00 393.58 4.74 394.10 17.65 393.07 0.00 393.59 4.96 394.11 17.76 393.08 0.00 393.60 5.19 394.12 17.86 393.09 0.00 393.61 5.42 394.13 17.96 393.10 0.00 393.62 5.65 394.14 18.07 393.11 0.00 393.63 5.89 394.15 18.17 393.12 0.00 393.64 6.13 394.16 18.27 393.13 0.00 393.65 6.37 394.17 18.37 393.14 0.00 393.66 6.62 394.18 18.47 393.15 0.00 393.67 6.87 394.19 18.57 393.16 0.00 393.68 7.12 394.20 18.67 393.17 0.00 393.69 7.38 394.21 18.77 393.18 0.00 393.70 7.64 394.22 18.87 393.19 0.00 393.71 7.90 394.23 18.97 393.20 0.00 393.72 8.16 394.24 19.07 393.21 0.00 393.73 8.43 394.25 19.16 393.22 0.00 393.74 8.70 394.26 19.26 393.23 0.00 393.75 8.97 394.27 19.36 393.24 0.00 393.76 9.25 394.28 19.45 393.25 0.00 393.77 9.53 394.29 19.55 393.26 0.00 393.78 9.81 394.30 19.64 393.27 0.03 393.79 10.09 393.28 0.07 393.80 10.38 393.29 0.14 393.81 10.67 393.30 0.21 393.82 10.96 393.31 0.29 393.83 11.26 393.32 0.38 393.84 11.56 393.33 0.48 393.85 11.86 393.34 0.59 393.86 12.16 393.35 0.71 393.87 12.46 393.36 0.83 393.88 12.77 393.37 0.95 393.89 13.08 393.38 1.09 393.90 13.39 393.39 1.23 393.91 13.71 393.40 1.37 393.92 14.03 393.41 1.52 393.93 14.35 393.42 1.67 393.94 14.67 393.43 1.83 393.95 14.99 393.44 2.00 393.96 15.32 393.45 2.17 393.97 15.65 393.46 2.34 393.98 15.98 393.47 2.52 393.99 16.32 393.48 2.70 394.00 16.57 393.49 2.89 394.01 16.68 393.50 3.08 394.02 16.79 393.51 3.27 394.03 16.90 Pre-Developed Type /I 24-hr 1 YR Rainfall=3.04" Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 11 Stage-Area-Storage for Pond 3P: EX. SWM Facility Elevation Surface Storage Elevation Surface Storage (feet) (sq-ft) (cubic-feet) (feet) (sq-ft) (cubic-feet) 393.00 1,900 0 394.04 4,575 3,712 393.02 1,978 39 394.06 4,592 3,803 393.04 2,055 79 394.08 4,609 3,895 393.06 2,133 121 394.10 4,627 3,988 393.08 2,210 164 394.12 4,644 4,081 393.10 2,288 209 394.14 4,661 4,174 393.12 2,365 256 394.16 4,679 4,267 393.14 2,443 304 394.18 4,696 4,361 393.16 2,520 354 394.20 4,713 4,455 393.18 2,598 405 394.22 4,731 4,549 393.20 2,676 458 394.24 4,748 4,644 393.22 2,753 512 394.26 4,765 4,739 393.24 2,831 568 394.28 4,783 4,835 393.26 2,908 625 394.30 4,800 4,931 393.28 2,986 684 393.30 3,063 745 393.32 3,141 807 393.34 3,219 870 393.36 3,296 935 393.38 3,374 1,002 393.40 3,451 1,070 393.42 3,529 1,140 393.44 3,606 1,211 393.46 3,684 1,284 393.48 3,761 1,359 393.50 3,839 1,435 393.52 3,867 1,512 393.54 3,895 1,589 393.56 3,923 1,668 393.58 3,951 1,746 393.60 3,979 1,826 393.62 4,007 1,906 393.64 4,035 1,986 393.66 4,063 2,067 393.68 4,091 2,148 393.70 4,119 2,231 393.72 4,147 2,313 393.74 4,175 2,396 393.76 4,204 2,480 393.78 4,232 2,565 393.80 4,260 2,650 393.82 4,288 2,735 393.84 4,316 2,821 393.86 4,344 2,908 393.88 4,372 2,995 393.90 4,400 3,083 393.92 4,428 3,171 393.94 4,456 3,260 393.96 4,484 3,349 393.98 4,512 3,439 394.00 4,540 3,530 394.02 4,557 3,620 Pre-Developed Type 1124-hr 10 YR Rainfall=5.56" Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 12 Summary for Subcatchment 2S: Ex. SWM Facility Drainage Area Runoff = 13.52 cfs @ 12.14 hrs, Volume= 0.983 af, Depth> 3.32" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 3.00-20.01 hrs, dt= 0.03 hrs Type II 24-hr 10 YR Rainfall=5.56" Area (ac) CN Description 1.230 98 Paved parking, HSG C 2.320 74 >75% Grass cover, Good, HSG C 3.550 82 Weighted Average 2.320 65.35% Pervious Area 1.230 34.65% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 19.7 200 0.0300 0.17 Sheet Flow, Grass: Dense n= 0.240 P2= 3.68" 1.8 150 0.0400 1.40 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 21.5 350 Total Subcatchment 2S: Ex. SWM Facility Drainage Area Hydrograph 15-/ 0 Runoff 14- I13s s J 13 Type II 24-hr 12= 10 YR Rainfall=5.56" 117 Runoff Area=3.550 ac 10- 9: Runoff Volume=0.983 of ^ 171 8- Runoff Depth>3.32" 71 Flow Length=350' 67 Tc=21.5 min CN=82 3. • 2: 1 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Pre-Developed Type l/24-hr 10 YR Rainfall=5.56" Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 sin 06538 ©2016 HydroCAD Software Solutions LLC Page 13 Hydrograph for Subcatchment 2S: Ex. SWM Facility Drainage Area Time Precip. Excess Runoff Time Precip. Excess Runoff (hours) (inches) (inches) (cfs) (hours) (inches) (inches) (cfs) 3.00 0.19 0.00 0.00 18.60 5.18 3.24 0.31 3.30 0.21 0.00 0.00 18.90 5.21 3.26 0.30 3.60 0.24 0.00 0.00 19.20 5.23 3.29 0.28 3.90 0.26 0.00 0.00 19.50 5.26 3.31 0.27 4.20 0.28 0.00 0.00 19.80 5.28 3.33 0.26 4.50 0.31 0.00 0.00 4.80 0.33 0.00 0.00 5.10 0.36 0.00 0.00 5.40 0.39 0.00 0.00 5.70 0.42 0.00 0.00 6.00 0.44 0.00 0.00 6.30 0.48 0.00 0.00 6.60 0.51 0.00 0.01 6.90 0.54 0.00 0.02 7.20 0.57 0.01 0.03 7.50 0.61 0.01 0.04 7.80 0.64 0.02 0.06 8.10 0.68 0.02 0.07 8.40 0.72 0.03 0.08 8.70 0.77 0.04 0.11 9.00 0.82 0.06 0.14 9.30 0.87 0.07 0.17 9.60 0.92 0.09 0.19 9.90 0.98 0.11 0.22 10.20 1.05 0.13 0.27 10.50 1.13 0.17 0.34 10.80 1.23 0.21 0.44 11.10 1.35 0.27 0.57 11.40 1.51 0.35 0.80 11.70 1.97 0.63 1.42 12.00 3.69 1.94 8.90 12.30 3.96 2.17 8.93 12.60 4.13 2.32 3.07 12.90 4.26 2.42 1.63 13.20 4.36 2.51 1.19 13.50 4.44 2.59 0.98 13.80 4.52 2.65 0.84 14.10 4.58 2.71 0.73 14.40 4.64 2.76 0.65 14.70 4.69 2.81 0.61 15.00 4.75 2.85 0.57 15.30 4.79 2.90 0.53 15.60 4.84 2.94 0.50 15.90 4.88 2.97 0.46 16.20 4.92 3.01 0.42 16.50 4.96 3.04 0.40 16.80 4.99 3.07 0.39 17.10 5.03 3.10 0.37 17.40 5.06 3.13 0.36 17.70 5.09 3.16 0.35 18.00 5.12 3.19 0.34 18.30 5.15 3.21 0.32 Pre-Developed Type 1124-hr 10 YR Rainfall=5.56" Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 14 Summary for Pond 3P: EX. SWM Facility Inflow Area = 3.550 ac, 34.65% Impervious, Inflow Depth > 3.32" for 10 YR event Inflow = 13.52 cfs @ 12.14 hrs, Volume= 0.983 of Outflow = 13.07 cfs @ 12.18 hrs, Volume= 0.965 af, Atten= 3%, Lag= 2.4 min Primary = 13.07 cfs @ 12.18 hrs, Volume= 0.965 af Routing by Stor-Ind method, Time Span= 3.00-20.01 hrs, dt= 0.03 hrs /3 Peak Elev= 393.89' @ 12.18 hrs Surf.Area= 4,385 sf Storage= 3,037 cf Plug-Flow detention time= 14.9 min calculated for 0.965 af (98% of inflow) Center-of-Mass det. time= 7.9 min ( 791.3 - 783.4 ) Volume Invert Avail.Storage Storage Description #1 393.00' 4,931 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 393.00 1,900 0 0 393.50 3,839 1,435 1,435 394.00 4,540 2,095 3,530 394.30 4,800 1,401 4,931 Device Routing Invert Outlet Devices #1 Primary 389.91' 24.0" Round Culvert L= 53.0' RCP, square edge headwall, Ke= 0.500 Inlet/Outlet Invert= 389.91' /389.62' S= 0.0055 '/' Cc= 0.900 n= 0.011 Concrete pipe, straight & clean, Flow Area= 3.14 sf #2 Device 1 393.26' 24.0" x 24.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=13.07 cfs @ 12.18 hrs HW=393.89' (Free Discharge) t-1=Culvert (Passes 13.07 cfs of 26.11 cfs potential flow) t-2=Orifice/Grate (Weir Controls 13.07 cfs @ 2.59 fps) Pre-Developed Type 1124-hr 10 YR Rainfall=5.56" Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 15 Pond 3P: EX. SWM Facility Hydrograph 15-/ ■Inflow 1 13.52 cfs I ®Primary 14_ Inflow Area=3.550 aro7ds 13' 12- Peak Elev=393.89' Stora e_3 037 cf w 9 0 7= 5� 4� 3 3: 3 4 5 6 7 8 9 10 11 12 13 —114-17• 16 17 18 19 20 Time (hours) Pond 3P: EX. SWM Facility Stage-Discharge i Primary 394- •• 11; • • ' �n* • x - Ortgatie w Fate 393 • • • • • • , . , , , . 0 2 4 6 8 10 12 14 16 18 Discharge (cfs) Pre-Developed Type 1124-hr 10 YR Rainfall=5.56" Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 16 Pond 3P: EX. SWM Facility Stage-Area-Storage Surface Honzontai Wetted Area{sq-ft} 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500 0 Surface II ®Storage 394- in' d c 0 a m w 393 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500 Storage(cubic-feet) Pre-Developed Type 1124-hr 10 YR Rainfall=5.56" Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 17 Hydrograph for Pond 3P: EX. SWM Facility Time Inflow Storage Elevation Primary (hours) (cfs) (cubic-feet) (feet) (cfs) 3.00 0.00 0 393.00 0.00 3.60 0.00 0 393.00 0.00 4.20 0.00 0 393.00 0.00 4.80 0.00 0 393.00 0.00 5.40 0.00 0 393.00 0.00 6.00 0.00 0 393.00 0.00 6.60 0.01 8 393.00 0.00 7.20 0.03 54 393.03 0.00 7.80 0.06 150 393.07 0.00 8.40 0.08 300 393.14 0.00 9.00 0.14 536 393.23 0.00 9.60 0.19 730 393.30 0.17 10.20 0.27 760 393.31 0.25 10.80 0.44 813 393.32 0.40 11.40 0.80 909 393.35 0.73 12.00 8.90 2,115 393.67 6.92 12.60 3.07 1,542 393.53 3.63 13.20 1.19 1,044 393.39 1.26 13.80 0.84 947 393.36 0.87 14.40 0.65 891 393.35 0.67 15.00 0.57 866 393.34 0.58 15.60 0.50 845 393.33 0.51 16.20 0.42 823 393.33 0.43 16.80 0.39 809 393.32 0.39 17.40 0.36 800 393.32 0.37 18.00 0.34 791 393.32 0.34 18.60 0.31 783 393.31 0.31 19.20 0.28 773 393.31 0.29 19.80 0.26 764 393.31 0.26 Pre-Developed Type 1124-hr 10 YR Rainfall=5.56" Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 18 Stage-Discharge for Pond 3P: EX. SWM Facility Elevation Primary Elevation Primary Elevation Primary (feet) (cfs) (feet) (cfs) (feet) (cfs) 393.00 0.00 393.52 3.47 394.04 17.01 393.01 0.00 393.53 3.67 394.05 17.12 393.02 0.00 393.54 3.88 394.06 17.23 393.03 0.00 393.55 4.09 394.07 17.33 393.04 0.00 393.56 4.30 394.08 17.44 393.05 0.00 393.57 4.52 394.09 17.55 393.06 0.00 393.58 4.74 394.10 17.65 393.07 0.00 393.59 4.96 394.11 17.76 393.08 0.00 393.60 5.19 394.12 17.86 393.09 0.00 393.61 5.42 394.13 17.96 393.10 0.00 393.62 5.65 394.14 18.07 393.11 0.00 393.63 5.89 394.15 18.17 393.12 0.00 393.64 6.13 394.16 18.27 393.13 0.00 393.65 6.37 394.17 18.37 393.14 0.00 393.66 6.62 394.18 18.47 393.15 0.00 393.67 6.87 394.19 18.57 393.16 0.00 393.68 7.12 394.20 18.67 393.17 0.00 393.69 7.38 394.21 18.77 393.18 0.00 393.70 7.64 394.22 18.87 393.19 0.00 393.71 7.90 394.23 18.97 393.20 0.00 393.72 8.16 394.24 19.07 393.21 0.00 393.73 8.43 394.25 19.16 393.22 0.00 393.74 8.70 394.26 19.26 393.23 0.00 393.75 8.97 394.27 19.36 393.24 0.00 393.76 9.25 394.28 19.45 393.25 0.00 393.77 9.53 394.29 19.55 393.26 0.00 393.78 9.81 394.30 19.64 393.27 0.03 393.79 10.09 393.28 0.07 393.80 10.38 393.29 0.14 393.81 10.67 393.30 0.21 393.82 10.96 393.31 0.29 393.83 11.26 393.32 0.38 393.84 11.56 393.33 0.48 393.85 11.86 393.34 0.59 393.86 12.16 393.35 0.71 393.87 12.46 393.36 0.83 393.88 12.77 393.37 0.95 393.89 13.08 393.38 1.09 393.90 13.39 393.39 1.23 393.91 13.71 393.40 1.37 393.92 14.03 393.41 1.52 393.93 14.35 393.42 1.67 393.94 14.67 393.43 1.83 393.95 14.99 393.44 2.00 393.96 15.32 393.45 2.17 393.97 15.65 393.46 2.34 393.98 15.98 393.47 2.52 393.99 16.32 393.48 2.70 394.00 16.57 393.49 2.89 394.01 16.68 393.50 3.08 394.02 16.79 393.51 3.27 394.03 16.90 Pre-Developed Type 1124-hr 10 YR Rainfall=5.56" Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 19 Stage-Area-Storage for Pond 3P: EX. SWM Facility Elevation Surface Storage Elevation Surface Storage (feet) (sq-ft) (cubic-feet) (feet) (sq-ft) (cubic-feet) 393.00 1,900 0 394.04 4,575 3,712 393.02 1,978 39 394.06 4,592 3,803 393.04 2,055 79 394.08 4,609 3,895 393.06 2,133 121 394.10 4,627 3,988 393.08 2,210 164 394.12 4,644 4,081 393.10 2,288 209 394.14 4,661 4,174 393.12 2,365 256 394.16 4,679 4,267 393.14 2,443 304 394.18 4,696 4,361 393.16 2,520 354 394.20 4,713 4,455 393.18 2,598 405 394.22 4,731 4,549 393.20 2,676 458 394.24 4,748 4,644 393.22 2,753 512 394.26 4,765 4,739 393.24 2,831 568 394.28 4,783 4,835 393.26 2,908 625 394.30 4,800 4,931 393.28 2,986 684 393.30 3,063 745 393.32 3,141 807 393.34 3,219 870 393.36 3,296 935 393.38 3,374 1,002 393.40 3,451 1,070 393.42 3,529 1,140 393.44 3,606 1,211 393.46 3,684 1,284 393.48 3,761 1,359 393.50 3,839 1,435 393.52 3,867 1,512 393.54 3,895 1,589 393.56 3,923 1,668 393.58 3,951 1,746 393.60 3,979 1,826 393.62 4,007 1,906 393.64 4,035 1,986 393.66 4,063 2,067 393.68 4,091 2,148 393.70 4,119 2,231 393.72 4,147 2,313 393.74 4,175 2,396 393.76 4,204 2,480 393.78 4,232 2,565 393.80 4,260 2,650 393.82 4,288 2,735 393.84 4,316 2,821 393.86 4,344 2,908 393.88 4,372 2,995 393.90 4,400 3,083 393.92 4,428 3,171 393.94 4,456 3,260 393.96 4,484 3,349 393.98 4,512 3,439 394.00 4,540 3,530 394.02 4,557 3,620 0 Post SW Facility Drainge Area AND Modified SWM Facility (Subc ) Reach 'on. Routing Diagram for Post-Developed Prepared by Timmons Group, Printed 8/2/2017 HydroCAD®10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Post-Developed Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 2 Area Listing (all nodes) Area CN Description (acres) (subcatchment-numbers) 2.220 74 >75% Grass cover, Good, HSG C (2S) 1.330 98 Paved parking, HSG C (2S) 3.550 83 TOTAL AREA Post-Developed Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 3 Pipe Listing (all nodes) Line# Node In-Invert Out-Invert Length Slope n Diam/Width Height Inside-Fill Number (feet) (feet) (feet) (ft/ft) (inches) (inches) (inches) 1 3P 389.91 389.62 53.0 0.0055 0.011 24.0 0.0 0.0 2 3P 390.00 389.95 8.0 0.0063 0.011 12.0 0.0 0.0 Post-Developed Type 1124-hr 1 YR Rainfall=3.04" Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 4 Summary for Subcatchment 2S: Post SWM Facility Draingae Area Runoff = 5.58 cfs @ 12.15 hrs, Volume= 0.400 af, Depth> 1.35" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-20.00 hrs, dt= 0.01 hrs Type II 24-hr 1 YR Rainfall=3.04" Area (ac) CN Description 1.330 98 Paved parking, HSG C 2.220 74 >75% Grass cover, Good, HSG C 3.550 83 Weighted Average 2.220 62.54% Pervious Area 1.330 37.46% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 19.7 200 0.0300 0.17 Sheet Flow, Grass: Dense n= 0.240 P2= 3.68" 1.8 150 0.0400 1.40 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 21.5 350 Total Subcatchment 2S: Post SWM Facility Draingae Area Hydrograph 6- 0 Runoff 5.58 cfs I Type II 24-hr 1 YR Rainfall_3.04" Runoff Area=3.550 ac 47 Runoff Volume=0.400 af Runoff Depth>1.35" o 3- Flow Length=350' Tc=21.5 min 2- CN=83 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Post-Developed Type 1124-hr 1 YR Rainfall=3.04" Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 5 Hydrograph for Subcatchment 2S: Post SWM Facility Draingae Area Time Precip. Excess Runoff Time Precip. Excess Runoff (hours) (inches) (inches) (cfs) (hours) (inches) (inches) (cfs) 0.00 0.00 0.00 0.00 10.40 0.60 0.02 0.06 0.20 0.01 0.00 0.00 10.60 0.64 0.02 0.08 0.40 0.01 0.00 0.00 10.80 0.67 0.03 0.10 0.60 0.02 0.00 0.00 11.00 0.71 0.04 0.13 0.80 0.03 0.00 0.00 11.20 0.76 0.05 0.17 1.00 0.03 0.00 0.00 11.40 0.83 0.07 0.23 1.20 0.04 0.00 0.00 11.60 0.93 0.11 0.31 1.40 0.05 0.00 0.00 11.80 1.31 0.27 0.83 1.60 0.05 0.00 0.00 12.00 2.02 0.71 3.42 1.80 0.06 0.00 0.00 12.20 2.12 0.78 5.28 2.00 0.07 0.00 0.00 12.40 2.20 0.84 2.52 2.20 0.07 0.00 0.00 12.60 2.26 0.88 1.37 2.40 0.08 0.00 0.00 12.80 2.31 0.91 0.87 2.60 0.09 0.00 0.00 13.00 2.35 0.94 0.66 2.80 0.10 0.00 0.00 13.20 2.38 0.97 0.55 3.00 0.10 0.00 0.00 13.40 2.41 0.99 0.48 3.20 0.11 0.00 0.00 13.60 2.44 1.01 0.43 3.40 0.12 0.00 0.00 13.80 2.47 1.03 0.39 3.60 0.13 0.00 0.00 14.00 2.49 1.05 0.36 3.80 0.14 0.00 0.00 14.20 2.51 1.07 0.33 4.00 0.15 0.00 0.00 14.40 2.54 1.08 0.30 4.20 0.15 0.00 0.00 14.60 2.56 1.10 0.29 4.40 0.16 0.00 0.00 14.80 2.58 1.11 0.28 4.60 0.17 0.00 0.00 15.00 2.59 1.13 0.27 4.80 0.18 0.00 0.00 15.20 2.61 1.14 0.26 5.00 0.19 0.00 0.00 15.40 2.63 1.15 0.25 5.20 0.20 0.00 0.00 15.60 2.65 1.17 0.24 5.40 0.21 0.00 0.00 15.80 2.66 1.18 0.22 5.60 0.22 0.00 0.00 16.00 2.68 1.19 0.21 5.80 0.23 0.00 0.00 16.20 2.69 1.20 0.20 6.00 0.24 0.00 0.00 16.40 2.70 1.21 0.19 6.20 0.25 0.00 0.00 16.60 2.72 1.22 0.19 6.40 0.27 0.00 0.00 16.80 2.73 1.23 0.18 6.60 0.28 0.00 0.00 17.00 2.74 1.24 0.18 6.80 0.29 0.00 0.00 17.20 2.75 1.25 0.18 7.00 0.30 0.00 0.00 17.40 2.77 1.26 0.17 7.20 0.31 0.00 0.00 17.60 2.78 1.27 0.17 7.40 0.33 0.00 0.00 17.80 2.79 1.28 0.17 7.60 0.34 0.00 0.00 18.00 2.80 1.29 0.16 7.80 0.35 0.00 0.00 18.20 2.81 1.30 0.16 8.00 0.36 0.00 0.00 18.40 2.82 1.30 0.15 8.20 0.38 0.00 0.00 18.60 2.83 1.31 0.15 8.40 0.39 0.00 0.00 18.80 2.84 1.32 0.14 8.60 0.41 0.00 0.00 19.00 2.85 1.33 0.14 8.80 0.43 0.00 0.00 19.20 2.86 1.33 0.14 9.00 0.45 0.00 0.00 19.40 2.87 1.34 0.13 9.20 0.47 0.00 0.01 19.60 2.88 1.35 0.13 9.40 0.49 0.00 0.01 19.80 2.89 1.36 0.12 9.60 0.51 0.00 0.02 20.00 2.89 1.36 0.12 9.80 0.53 0.01 0.03 10.00 0.55 0.01 0.04 10.20 0.58 0.01 0.05 Post-Developed Type 1124-hr 1 YR Rainfall=3.04" Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 6 Summary for Pond 3P: Modified SWM Facility Inflow Area = 3.550 ac, 37.46% Impervious, Inflow Depth > 1.35" for 1 YR event Inflow = 5.58 cfs @ 12.15 hrs, Volume= 0.400 af Outflow = 3.74 cfs @ 12.30 hrs, Volume= 0.390 af, Atten= 33%, Lag= 9.2 min Primary = 3.74 cfs @ 12.30 hrs, Volume= 0.390 of Routing by Stor-Ind method, Time Span= 0.00-20.00 hrs, dt= 0.01 hrs /3 Peak Elev= 391.54' @ 12.30 hrs Surf.Area= 2,859 sf Storage= 3,819 cf Plug-Flow detention time= 27.2 min calculated for 0.390 of (97% of inflow) Center-of-Mass det. time= 17.7 min ( 818.9 - 801.2 ) Volume Invert Avail.Storage Storage Description #1 390.00' 14,303 cf Custom Stage Data(Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 390.00 2,107 0 0 391.00 2,581 2,344 2,344 392.00 3,094 2,838 5,182 393.00 3,785 3,440 8,621 394.00 4,723 4,254 12,875 394.30 4,800 1,428 14,303 Device Routing Invert Outlet Devices #1 Primary 389.91' 24.0" Round Culvert L= 53.0' RCP, square edge headwall, Ke= 0.500 Inlet/Outlet Invert= 389.91' /389.62' S= 0.0055 '/' Cc= 0.900 n= 0.011 Concrete pipe, straight & clean, Flow Area= 3.14 sf #2 Device 1 392.47' 24.0" x 24.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Device 1 390.00' 12.0" Round Culvert L= 8.0' RCP, square edge headwall, Ke= 0.500 Inlet/Outlet Invert= 390.00' /389.95' S= 0.0063 '/' Cc= 0.900 n= 0.011 Concrete pipe, straight & clean, Flow Area= 0.79 sf Primary OutFlow Max=3.74 cfs @ 12.30 hrs HW=391.54' (Free Discharge) L1=Culvert (Passes 3.74 cfs of 9.79 cfs potential flow) L2=Orifice/Grate ( Controls 0.00 cfs) 3=Culvert (Barrel Controls 3.74 cfs © 4.76 fps) Post-Developed Type 11 24-hr 1 YR Rainfall=3.04" Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 7 Pond 3P: Modified SWM Facility Hydrograph / Inflow ■0 Primary Inflow Area=3.550 ac 5- Peak Elev=391 .54' Storage=3,819 cf 4 1 3.74 cts N V 3 3- o 2- 1- 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Pond 3P: Modified SWM Facility Stage-Discharge 0 Primary 394- 393- _ m c - 0 .� 392- a d - w 391 fAAVOtt 390 . . 0 2 4 6 8 10 12 14 16 18 20 221 24 26 Discharge (cfs) Post-Developed Type l/24-hr 1 YR Rainfall=3.04" Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 8 Pond 3P: Modified SWM Facility Stage-Area-Storage Surface Horizontal Wetted Area(sq-ft) 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500 0 Surface // ®Storage 394- 393- - 94- 393-- c - 0 ft, 392- > m ' W - 7 391- 390 0 2,000 4,000 6,000 8,000 10,000 12,000 14,000 Storage(cubic-feet) Post-Developed Type 1124-hr 1 YR Rainfall=3.04" Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 9 Hydrograph for Pond 3P: Modified SWM Facility Time Inflow Storage Elevation Primary (hours) (cfs) (cubic-feet) (feet) (cfs) 0.00 0.00 0 390.00 0.00 0.50 0.00 0 390.00 0.00 1.00 0.00 0 390.00 0.00 1.50 0.00 0 390.00 0.00 2.00 0.00 0 390.00 0.00 2.50 0.00 0 390.00 0.00 3.00 0.00 0 390.00 0.00 3.50 0.00 0 390.00 0.00 4.00 0.00 0 390.00 0.00 4.50 0.00 0 390.00 0.00 5.00 0.00 0 390.00 0.00 5.50 0.00 0 390.00 0.00 6.00 0.00 0 390.00 0.00 6.50 0.00 0 390.00 0.00 7.00 0.00 0 390.00 0.00 7.50 0.00 0 390.00 0.00 8.00 0.00 0 390.00 0.00 8.50 0.00 0 390.00 0.00 9.00 0.00 1 390.00 0.00 9.50 0.02 18 390.01 0.00 10.00 0.04 60 390.03 0.00 10.50 0.07 137 390.06 0.02 11.00 0.13 256 390.12 0.05 11.50 0.26 438 390.20 0.13 12.00 3.42 1,572 390.69 1.21 12.50 1.81 3,212 391.33 3.00 13.00 0.66 1,515 390.67 1.14 13.50 0.46 1,029 390.46 0.60 14.00 0.36 848 390.39 0.43 14.50 0.30 742 390.34 0.34 15.00 0.27 682 390.31 0.29 15.50 0.24 641 390.29 0.26 16.00 0.21 602 390.28 0.23 16.50 0.19 564 390.26 0.21 17.00 0.18 539 390.25 0.19 17.50 0.17 520 390.24 0.18 18.00 0.16 503 390.23 0.17 18.50 0.15 487 390.23 0.16 19.00 0.14 470 390.22 0.15 19.50 0.13 453 390.21 0.14 20.00 0.12 435 390.20 0.13 Post-Developed Type 1/24-hr 1 YR Rainfall=3.04" Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 10 Stage-Discharge for Pond 3P: Modified SWM Facility Elevation Primary Elevation Primary (feet) (cfs) (feet) (cfs) 390.00 0.00 392.60 6.71 390.05 0.01 392.65 7.54 390.10 0.03 392.70 8.49 390.15 0.07 392.75 9.55 390.20 0.13 392.80 10.69 390.25 0.19 392.85 11.93 390.30 0.27 392.90 13.23 390.35 0.36 392.95 14.62 390.40 0.46 393.00 16.07 390.45 0.57 393.05 17.59 390.50 0.69 393.10 19.18 390.55 0.81 393.15 20.83 390.60 0.94 393.20 22.53 390.65 1.08 393.25 22.92 390.70 1.23 393.30 23.26 390.75 1.38 393.35 23.61 390.80 1.53 393.40 23.87 390.85 1.69 393.45 24.11 390.90 1.85 393.50 24.34 390.95 2.01 393.55 24.58 391.00 2.17 393.60 24.81 391.05 2.33 393.65 25.04 391.10 2.48 393.70 25.27 391.15 2.62 393.75 25.49 391.20 2.76 393.80 25.72 391.25 2.88 393.85 25.94 391.30 2.98 393.90 26.16 391.35 3.08 393.95 26.37 391.40 3.26 394.00 26.59 391.45 3.44 394.05 26.80 391.50 3.61 394.10 27.02 391.55 3.77 394.15 27.23 391.60 3.92 394.20 27.44 391.65 4.06 394.25 27.65 391.70 4.14 394.30 27.85 391.75 4.23 391.80 4.31 391.85 4.39 391.90 4.47 391.95 4.55 392.00 4.63 392.05 4.71 392.10 4.78 392.15 4.86 392.20 4.93 392.25 5.00 392.30 5.07 392.35 5.14 392.40 5.21 392.45 5.28 392.50 5.48 392.55 6.01 Post-Developed Type l/24-hr 1 YR Rainfall=3.04" Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 11 Stage-Area-Storage for Pond 3P: Modified SWM Facility Elevation Surface Storage Elevation Surface Storage (feet) (sq-ft) (cubic-feet) (feet) (sq-ft) (cubic-feet) 390.00 2,107 0 392.60 3,509 7,162 390.05 2,131 106 392.65 3,543 7,339 390.10 2,154 213 392.70 3,578 7,517 390.15 2,178 321 392.75 3,612 7,696 390.20 2,202 431 392.80 3,647 7,878 390.25 2,226 542 392.85 3,681 8,061 390.30 2,249 653 392.90 3,716 8,246 390.35 2,273 766 392.95 3,750 8,433 390.40 2,297 881 393.00 3,785 8,621 390.45 2,320 996 393.05 3,832 8,811 390.50 2,344 1,113 393.10 3,879 9,004 390.55 2,368 1,231 393.15 3,926 9,199 390.60 2,391 1,350 393.20 3,973 9,397 390.65 2,415 1,470 393.25 4,020 9,597 390.70 2,439 1,591 393.30 4,066 9,799 390.75 2,463 1,714 393.35 4,113 10,003 390.80 2,486 1,837 393.40 4,160 10,210 390.85 2,510 1,962 393.45 4,207 10,419 390.90 2,534 2,088 393.50 4,254 10,631 390.95 2,557 2,216 393.55 4,301 10,845 391.00 2,581 2,344 393.60 4,348 11,061 391.05 2,607 2,474 393.65 4,395 11,279 391.10 2,632 2,605 393.70 4,442 11,500 391.15 2,658 2,737 393.75 4,489 11,724 391.20 2,684 2,870 393.80 4,535 11,949 391.25 2,709 3,005 393.85 4,582 12,177 391.30 2,735 3,141 393.90 4,629 12,407 391.35 2,761 3,279 393.95 4,676 12,640 391.40 2,786 3,417 394.00 4,723 12,875 391.45 2,812 3,557 394.05 4,736 13,111 391.50 2,838 3,699 394.10 4,749 13,349 391.55 2,863 3,841 394.15 4,761 13,586 391.60 2,889 3,985 394.20 4,774 13,825 391.65 2,914 4,130 394.25 4,787 14,064 391.70 2,940 4,276 394.30 4,800 14,303 391.75 2,966 4,424 391.80 2,991 4,573 391.85 3,017 4,723 391.90 3,043 4,875 391.95 3,068 5,027 392.00 3,094 5,182 392.05 3,129 5,337 392.10 3,163 5,494 392.15 3,198 5,653 392.20 3,232 5,814 392.25 3,267 5,977 392.30 3,301 6,141 392.35 3,336 6,307 392.40 3,370 6,474 392.45 3,405 6,644 392.50 3,440 6,815 392.55 3,474 6,988 Post-Developed Type 1124-hr 10 YR Rainfall=5.56" Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 12 Summary for Subcatchment 2S: Post SWM Facility Draingae Area Runoff = 13.87 cfs @ 12.14 hrs, Volume= 1.011 af, Depth> 3.42" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-20.00 hrs, dt= 0.01 hrs Type II 24-hr 10 YR Rainfall=5.56" Area (ac) CN Description 1.330 98 Paved parking, HSG C 2.220 74 >75% Grass cover, Good, HSG C 3.550 83 Weighted Average 2.220 62.54% Pervious Area 1.330 37.46% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 19.7 200 0.0300 0.17Sheet w, Grass:FDI n= 0.240 P2= 3.68" 1.8 150 0.0400 1.40 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 21.5 350 Total Subcatchment 2S: Post SWM Facility Draingae Area Hydrograph Runoff 14- 113.87 cis I 14- Type II 24-hr 12_ 10 YR Rainfall_5.56" i Runoff Area-3.550 ac 191 Runoff Volume-1.011 af $= Runoff Depth>3.42" 7- Flow Length=350' Tc=21 .5 min CN=83 3- pd` 1 2 3 4 5 6 7 8 9 10 11 72 13 14 15 16 17 18 19 20 Time (hours) Post-Developed Type 1124-hr 10 YR Rainfall=5.56" Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 13 Hydrograph for Subcatchment 2S: Post SWM Facility Draingae Area Time Precip. Excess Runoff Time Precip. Excess Runoff (hours) (inches) (inches) (cfs) (hours) (inches) (inches) (cfs) 0.00 0.00 0.00 0.00 10.40 1.11 0.18 0.34 0.20 0.01 0.00 0.00 10.60 1.16 0.20 0.40 0.40 0.02 0.00 0.00 10.80 1.23 0.24 0.47 0.60 0.03 0.00 0.00 11.00 1.31 0.27 0.56 0.80 0.05 0.00 0.00 11.20 1.40 0.32 0.67 1.00 0.06 0.00 0.00 11.40 1.51 0.38 0.85 1.20 0.07 0.00 0.00 11.60 1.71 0.50 1.11 1.40 0.08 0.00 0.00 11.80 2.40 0.98 2.63 1.60 0.10 0.00 0.00 12.00 3.69 2.02 9.18 1.80 0.11 0.00 0.00 12.20 3.88 2.19 12.91 2.00 0.12 0.00 0.00 12.40 4.03 2.31 5.96 2.20 0.14 0.00 0.00 12.60 4.13 2.40 3.13 2.40 0.15 0.00 0.00 12.80 4.22 2.48 1.95 2.60 0.16 0.00 0.00 13.00 4.29 2.54 1.46 2.80 0.18 0.00 0.00 13.20 4.36 2.60 1.20 3.00 0.19 0.00 0.00 13.40 4.42 2.65 1.06 3.20 0.21 0.00 0.00 13.60 4.47 2.70 0.95 3.40 0.22 0.00 0.00 13.80 4.52 2.74 0.85 3.60 0.24 0.00 0.00 14.00 4.56 2.78 0.77 3.80 0.25 0.00 0.00 14.20 4.60 2.81 0.70 4.00 0.27 0.00 0.00 14.40 4.64 2.85 0.66 4.20 0.28 0.00 0.00 14.60 4.68 2.88 0.63 4.40 0.30 0.00 0.00 14.80 4.71 2.91 0.60 4.60 0.32 0.00 0.00 15.00 4.75 2.94 0.58 4.80 0.33 0.00 0.00 15.20 4.78 2.97 0.55 5.00 0.35 0.00 0.00 15.40 4.81 3.00 0.53 5.20 0.37 0.00 0.00 15.60 4.84 3.03 0.50 5.40 0.39 0.00 0.00 15.80 4.87 3.05 0.48 5.60 0.41 0.00 0.00 16.00 4.89 3.08 0.45 5.80 0.43 0.00 0.00 16.20 4.92 3.10 0.43 6.00 0.44 0.00 0.00 16.40 4.94 3.12 0.41 6.20 0.47 0.00 0.01 16.60 4.97 3.14 0.40 6.40 0.49 0.00 0.01 16.80 4.99 3.17 0.39 6.60 0.51 0.00 0.02 17.00 5.01 3.19 0.38 6.80 0.53 0.01 0.03 17.20 5.04 3.21 0.37 7.00 0.55 0.01 0.04 17.40 5.06 3.23 0.37 7.20 0.57 0.01 0.04 17.60 5.08 3.25 0.36 7.40 0.60 0.02 0.05 17.80 5.10 3.27 0.35 7.60 0.62 0.02 0.06 18.00 5.12 3.28 0.34 7.80 0.64 0.02 0.07 18.20 5.14 3.30 0.33 8.00 0.67 0.03 0.08 18.40 5.16 3.32 0.32 8.20 0.69 0.03 0.09 18.60 5.18 3.34 0.31 8.40 0.72 0.04 0.10 18.80 5.20 3.35 0.30 8.60 0.75 0.05 0.12 19.00 5.21 3.37 0.30 8.80 0.78 0.06 0.13 19.20 5.23 3.38 0.29 9.00 0.82 0.07 0.16 19.40 5.25 3.40 0.28 9.20 0.85 0.08 0.18 19.60 5.26 3.41 0.27 9.40 0.89 0.09 0.20 19.80 5.28 3.43 0.26 9.60 0.92 0.10 0.21 20.00 5.29 3.44 0.25 9.80 0.96 0.12 0.23 10.00 1.01 0.13 0.26 10.20 1.05 0.15 0.29 Post-Developed Type l/24-hr 10 YR Rainfall=5.56" Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 14 Summary for Pond 3P: Modified SWM Facility Inflow Area = 3.550 ac, 37.46% Impervious, Inflow Depth > 3.42" for 10 YR event Inflow = 13.87 cfs @ 12.14 hrs, Volume= 1.011 af Outflow = 12.28 cfs @ 12.22 hrs, Volume= 0.996 af, Atten= 11%, Lag= 4.8 min Primary = 12.28 cfs @ 12.22 hrs, Volume= 0.996 of Routing by Stor-Ind method, Time Span= 0.00-20.00 hrs, dt= 0.01 hrs/3 Peak Elev= 392.86' @ 12.22 hrs Surf.Area= 3,691 sf Storage= 8,111 cf Plug-Flow detention time= 21.9 min calculated for 0.996 of (98% of inflow) Center-of-Mass det. time= 15.9 min ( 796.9 - 781.0 ) Volume Invert Avail.Storage Storage Description #1 390.00' 14,303 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 390.00 2,107 0 0 391.00 2,581 2,344 2,344 392.00 3,094 2,838 5,182 393.00 3,785 3,440 8,621 394.00 4,723 4,254 12,875 394.30 4,800 1,428 14,303 Device Routing Invert Outlet Devices #1 Primary 389.91' 24.0" Round Culvert L. 53.0' RCP, square edge headwall, Ke= 0.500 Inlet/Outlet Invert= 389.91'/389.62' S= 0.0055 '/' Cc= 0.900 n= 0.011 Concrete pipe, straight & clean, Flow Area= 3.14 sf #2 Device 1 392.47' 24.0"x 24.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Device 1 390.00' 12.0" Round Culvert L= 8.0' RCP, square edge headwall, Ke= 0.500 Inlet/Outlet Invert= 390.00' /389.95' S= 0.0063 '/' Cc= 0.900 n= 0.011 Concrete pipe, straight & clean, Flow Area= 0.79 sf Primary OutFlow Max=12.27 cfs @ 12.22 hrs HW=392.86' (Free Discharge) t-1=Culvert (Passes 12.27 cfs of 20.02 cfs potential flow) - 2=Orifice/Grate (Weir Controls 6.46 cfs @ 2.05 fps) 3=Culvert (Inlet Controls 5.81 cfs @ 7.40 fps) Post-Developed Type 11 24-hr 10 YR Rainfall=5.56" Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00 19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 15 Pond 3P: Modified SWM Facility Hydrograph / ■Inflowary 15-i 113.87cfs( l®Prim 14= Inflow Area=3.550 ac 13-- Peak Elev=392.86' 11228cs 12= 11 7] Storage=8,111 cf N 9_ _ Y t 3 _c 7_ u. : 6- 5= 4= 0 `.....ri it •,'. , i ., 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Pond 3P: Modified SWM Facility Stage-Discharge 394- 0 Primary 393- a r ;.. m 0 - 0 is 392- o - W 391- Caked 390 0 2 4 6 8 10 12 14 16 18 20 221 24 26 Discharge (cfs) Post-Developed Type 1124-hr 10 YR Rainfall=5.56" Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 16 Pond 3P: Modified SWM Facility Stage-Area-Storage Surface Horizontal Wetted Area(sq-ft) 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500 I 0 Surface // ®Storage 394- 393- c 94-393-c - 0 392- co 3 _ W - 391- 390 . , . . , . , . . , 0 2,000 4,000 6,000 8,000 10,000 12,000 14,000 Storage(cubic-feet) Post-Developed Type 1124-hr 10 YR Rainfall=5.56" Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 17 Hydrograph for Pond 3P: Modified SWM Facility Time Inflow Storage Elevation Primary (hours) (cfs) (cubic-feet) (feet) (cfs) 0.00 0.00 0 390.00 0.00 0.50 0.00 0 390.00 0.00 1.00 0.00 0 390.00 0.00 1.50 0.00 0 390.00 0.00 2.00 0.00 0 390.00 0.00 2.50 0.00 0 390.00 0.00 3.00 0.00 0 390.00 0.00 3.50 0.00 0 390.00 0.00 4.00 0.00 0 390.00 0.00 4.50 0.00 0 390.00 0.00 5.00 0.00 0 390.00 0.00 5.50 0.00 0 390.00 0.00 6.00 0.00 1 390.00 0.00 6.50 0.02 17 390.01 0.00 7.00 0.04 62 390.03 0.00 7.50 0.06 131 390.06 0.01 8.00 0.08 211 390.10 0.03 8.50 0.11 290 390.14 0.06 9.00 0.16 380 390.18 0.10 9.50 0.20 478 390.22 0.15 10.00 0.26 559 390.26 0.21 10.50 0.37 675 390.31 0.29 11.00 0.56 854 390.39 0.44 11.50 0.97 1,154 390.52 0.73 12.00 9.18 3,835 391.55 3.76 12.50 4.21 6,826 392.50 5.53 13.00 1.46 3,149 391.30 2.98 13.50 1.00 1,675 390.73 1.33 14.00 0.77 1,312 390.58 0.90 14.50 0.64 1,135 390.51 0.71 15.00 0.58 1,044 390.47 0.62 15.50 0.52 978 390.44 0.55 16.00 0.45 914 390.41 0.49 16.50 0.41 853 390.39 0.43 17.00 0.38 814 390.37 0.40 17.50 0.36 786 390.36 0.38 18.00 0.34 759 390.35 0.35 18.50 0.32 733 390.34 0.33 19.00 0.30 705 390.32 0.31 19.50 0.27 676 390.31 0.29 20.00 0.25 648 390.30 0.27 Post-Developed Type 1124-hr 10 YR Rainfall=5.56" Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 18 Stage-Discharge for Pond 3P: Modified SWM Facility Elevation Primary Elevation Primary (feet) (cfs) (feet) (cfs) 390.00 0.00 392.60 6.71 390.05 0.01 392.65 7.54 390.10 0.03 392.70 8.49 390.15 0.07 392.75 9.55 390.20 0.13 392.80 10.69 390.25 0.19 392.85 11.93 390.30 0.27 392.90 13.23 390.35 0.36 392.95 14.62 390.40 0.46 393.00 16.07 390.45 0.57 393.05 17.59 390.50 0.69 393.10 19.18 390.55 0.81 393.15 20.83 390.60 0.94 393.20 22.53 390.65 1.08 393.25 22.92 390.70 1.23 393.30 23.26 390.75 1.38 393.35 23.61 390.80 1.53 393.40 23.87 390.85 1.69 393.45 24.11 390.90 1.85 393.50 24.34 390.95 2.01 393.55 24.58 391.00 2.17 393.60 24.81 391.05 2.33 393.65 25.04 391.10 2.48 393.70 25.27 391.15 2.62 393.75 25.49 391.20 2.76 393.80 25.72 391.25 2.88 393.85 25.94 391.30 2.98 393.90 26.16 391.35 3.08 393.95 26.37 391.40 3.26 394.00 26.59 391.45 3.44 394.05 26.80 391.50 3.61 394.10 27.02 391.55 3.77 394.15 27.23 391.60 3.92 394.20 27.44 391.65 4.06 394.25 27.65 391.70 4.14 394.30 27.85 391.75 4.23 391.80 4.31 391.85 4.39 391.90 4.47 391.95 4.55 392.00 4.63 392.05 4.71 392.10 4.78 392.15 4.86 392.20 4.93 392.25 5.00 392.30 5.07 392.35 5.14 392.40 5.21 392.45 5.28 392.50 5.48 392.55 6.01 Post-Developed Type 1124-hr 10 YR Rainfall=5.56" Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 19 Stage-Area-Storage for Pond 3P: Modified SWM Facility Elevation Surface Storage Elevation Surface Storage (feet) (sq-ft) (cubic-feet) (feet) (sq-ft) (cubic-feet) 390.00 2,107 0 392.60 3,509 7,162 390.05 2,131 106 392.65 3,543 7,339 390.10 2,154 213 392.70 3,578 7,517 390.15 2,178 321 392.75 3,612 7,696 390.20 2,202 431 392.80 3,647 7,878 390.25 2,226 542 392.85 3,681 8,061 390.30 2,249 653 392.90 3,716 8,246 390.35 2,273 766 392.95 3,750 8,433 390.40 2,297 881 393.00 3,785 8,621 390.45 2,320 996 393.05 3,832 8,811 390.50 2,344 1,113 393.10 3,879 9,004 390.55 2,368 1,231 393.15 3,926 9,199 390.60 2,391 1,350 393.20 3,973 9,397 390.65 2,415 1,470 393.25 4,020 9,597 390.70 2,439 1,591 393.30 4,066 9,799 390.75 2,463 1,714 393.35 4,113 10,003 390.80 2,486 1,837 393.40 4,160 10,210 390.85 2,510 1,962 393.45 4,207 10,419 390.90 2,534 2,088 393.50 4,254 10,631 390.95 2,557 2,216 393.55 4,301 10,845 391.00 2,581 2,344 393.60 4,348 11,061 391.05 2,607 2,474 393.65 4,395 11,279 391.10 2,632 2,605 393.70 4,442 11,500 391.15 2,658 2,737 393.75 4,489 11,724 391.20 2,684 2,870 393.80 4,535 11,949 391.25 2,709 3,005 393.85 4,582 12,177 391.30 2,735 3,141 393.90 4,629 12,407 391.35 2,761 3,279 393.95 4,676 12,640 391.40 2,786 3,417 394.00 4,723 12,875 391.45 2,812 3,557 394.05 4,736 13,111 391.50 2,838 3,699 394.10 4,749 13,349 391.55 2,863 3,841 394.15 4,761 13,586 391.60 2,889 3,985 394.20 4,774 13,825 391.65 2,914 4,130 394.25 4,787 14,064 391.70 2,940 4,276 394.30 4,800 14,303 391.75 2,966 4,424 391.80 2,991 4,573 391.85 3,017 4,723 391.90 3,043 4,875 391.95 3,068 5,027 392.00 3,094 5,182 392.05 3,129 5,337 392.10 3,163 5,494 392.15 3,198 5,653 392.20 3,232 5,814 392.25 3,267 5,977 392.30 3,301 6,141 392.35 3,336 6,307 392.40 3,370 6,474 392.45 3,405 6,644 392.50 3,440 6,815 392.55 3,474 6,988 Post-Developed Type 1124-hr 100 YR Rainfall=9.13" Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 20 Summary for Subcatchment 2S: Post SWM Facility Draingae Area Runoff = 25.97 cfs @ 12.14 hrs, Volume= 1.953 af, Depth> 6.60" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-20.00 hrs, dt= 0.01 hrs Type II 24-hr 100 YR Rainfall=9.13" Area (ac) CN Description 1.330 98 Paved parking, HSG C 2.220 74 >75% Grass cover, Good, HSG C 3.550 83 Weighted Average 2.220 62.54% Pervious Area 1.330 37.46% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 19.7 200 0.0300 0.17 Sheet Flow, Grass: Dense n= 0.240 P2= 3.68" 1.8 150 0.0400 1.40 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 21.5 350 Total Subcatchment 2S: Post SWM Facility Draingae Area Hydrograph 28. a Runoff 125.97 cfs 26::. 6 Type II 24-hr 24_ 22- 100 YR Rainfall=9.13" 20- Runoff Area_3.550 ac 18- Runoff Volume=1.953 of 16 Runoff Depth>6.60" 14- E- 12- Flow Length=350' Tc=21.5 min 8 CN=83 6-: a l bD 0 w. 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Post-Developed Type /l 24-hr 100 YR Rainfall=9.13" Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 21 Hydrograph for Subcatchment 2S: Post SWM Facility Draingae Area Time Precip. Excess Runoff Time Precip. Excess Runoff (hours) (inches) (inches) (cfs) (hours) (inches) (inches) (cfs) 0.00 0.00 0.00 0.00 10.40 1.82 0.57 0.85 0.20 0.02 0.00 0.00 10.60 1.91 0.64 0.97 0.40 0.04 0.00 0.00 10.80 2.02 0.71 1.11 0.60 0.06 0.00 0.00 11.00 2.15 0.80 1.30 0.80 0.08 0.00 0.00 11.20 2.29 0.90 1.53 1.00 0.10 0.00 0.00 11.40 2.48 1.04 1.89 1.20 0.12 0.00 0.00 11.60 2.80 1.29 2.40 1.40 0.14 0.00 0.00 11.80 3.93 2.23 5.47 1.60 0.16 0.00 0.00 12.00 6.05 4.14 17.80 1.80 0.18 0.00 0.00 12.20 6.38 4.44 23.96 2.00 0.20 0.00 0.00 12.40 6.62 4.67 10.87 2.20 0.22 0.00 0.00 12.60 6.79 4.83 5.63 2.40 0.25 0.00 0.00 12.80 6.93 4.96 3.47 2.60 0.27 0.00 0.00 13.00 7.05 5.07 2.58 2.80 0.29 0.00 0.00 13.20 7.15 5.17 2.12 3.00 0.31 0.00 0.00 13.40 7.25 5.26 1.86 3.20 0.34 0.00 0.00 13.60 7.34 5.35 1.66 3.40 0.36 0.00 0.00 13.80 7.42 5.42 1.49 3.60 0.39 0.00 0.00 14.00 7.49 5.49 1.36 3.80 0.41 0.00 0.00 14.20 7.55 5.55 1.23 4.00 0.44 0.00 0.00 14.40 7.62 5.61 1.15 4.20 0.46 0.00 0.01 14.60 7.68 5.67 1.10 4.40 0.49 0.00 0.02 14.80 7.74 5.73 1.05 4.60 0.52 0.01 0.03 15.00 7.79 5.78 1.01 4.80 0.55 0.01 0.04 15.20 7.85 5.83 0.96 5.00 0.58 0.01 0.05 15.40 7.90 5.88 0.92 5.20 0.60 0.02 0.07 15.60 7.95 5.93 0.88 5.40 0.64 0.02 0.08 15.80 7.99 5.97 0.83 5.60 0.67 0.03 0.09 16.00 8.03 6.01 0.79 5.80 0.70 0.04 0.11 16.20 8.08 6.05 0.75 6.00 0.73 0.04 0.12 16.40 8.12 6.09 0.72 6.20 0.76 0.05 0.14 16.60 8.16 6.13 0.70 6.40 0.80 0.06 0.15 16.80 8.20 6.16 0.68 6.60 0.83 0.07 0.17 17.00 8.23 6.20 0.67 6.80 0.87 0.08 0.19 17.20 8.27 6.24 0.65 7.00 0.90 0.10 0.20 17.40 8.31 6.27 0.64 7.20 0.94 0.11 0.22 17.60 8.34 6.30 0.62 7.40 0.98 0.12 0.24 17.80 8.38 6.34 0.61 7.60 1.02 0.14 0.25 18.00 8.41 6.37 0.59 7.80 1.06 0.15 0.27 18.20 8.44 6.40 0.57 8.00 1.10 0.17 0.29 18.40 8.47 6.43 0.56 8.20 1.14 0.19 0.31 18.60 8.50 6.46 0.54 8.40 1.18 0.21 0.33 18.80 8.53 6.49 0.53 8.60 1.23 0.24 0.37 19.00 8.56 6.52 0.51 8.80 1.29 0.26 0.42 19.20 8.59 6.54 0.50 9.00 1.34 0.29 0.47 19.40 8.62 6.57 0.48 9.20 1.40 0.32 0.52 19.60 8.64 6.59 0.47 9.40 1.46 0.36 0.55 19.80 8.67 6.62 0.45 9.60 1.52 0.39 0.57 20.00 8.69 6.64 0.43 9.80 1.58 0.43 0.61 10.00 1.65 0.47 0.67 10.20 1.73 0.52 0.75 Post-Developed Type 1124-hr 100 YR Rainfall=9.13" Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 sin 06538 ©2016 HydroCAD Software Solutions LLC Page 22 Summary for Pond 3P: Modified SWM Facility Inflow Area = 3.550 ac, 37.46% Impervious, Inflow Depth > 6.60" for 100 YR event Inflow = 25.97 cfs @ 12.14 hrs, Volume= 1.953 of Outflow = 23.82 cfs @ 12.20 hrs, Volume= 1.933 af, Atten= 8%, Lag= 4.0 min Primary = 23.82 cfs @ 12.20 hrs, Volume= 1.933 af Routing by Stor-Ind method, Time Span= 0.00-20.00 hrs, dt= 0.01 hrs/3 Peak Elev= 393.39' @ 12.20 hrs Surf.Area= 4,151 sf Storage= 10,170 cf Plug-Flow detention time= 17.1 min calculated for 1.933 af (99% of inflow) Center-of-Mass det. time= 12.7 min ( 778.4 - 765.6 ) Volume Invert Avail.Storage Storage Description #1 390.00' 14,303 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 390.00 2,107 0 0 391.00 2,581 2,344 2,344 392.00 3,094 2,838 5,182 393.00 3,785 3,440 8,621 394.00 4,723 4,254 12,875 394.30 4,800 1,428 14,303 Device Routing Invert Outlet Devices #1 Primary 389.91' 24.0" Round Culvert L= 53.0' RCP, square edge headwall, Ke= 0.500 Inlet/Outlet Invert= 389.91'/389.62' S= 0.0055 '/' Cc= 0.900 n= 0.011 Concrete pipe, straight & clean, Flow Area= 3.14 sf #2 Device 1 392.47' 24.0" x 24.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Device 1 390.00' 12.0" Round Culvert L= 8.0' RCP, square edge headwall, Ke= 0.500 Inlet/Outlet Invert= 390.00' /389.95' S= 0.0063 '/' Cc= 0.900 n= 0.011 Concrete pipe, straight & clean, Flow Area= 0.79 sf Primary OutFlow Max=23.82 cfs @ 12.20 hrs HW=393.39' (Free Discharge) t-1=Culvert (Inlet Controls 23.82 cfs @ 7.58 fps) -2=Orifice/Grate (Passes < 18.47 cfs potential flow) 3=Culvert (Passes < 6.43 cfs potential flow) Post-Developed Type /l 24-hr 100 YR Rainfall=9.13" Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 23 Pond 3P: Modified SWM Facility Hydrograph / ■Inflow 28- i 25.97cfs i ®Primary 26 Inflow Area=3.550 ac 123.82 cfs 24= Peak Elev=393.39' 20_ Storage=10,170 cf 18- 16= c 14= :" 10 8 6 4 s: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Pond 3P: Modified SWM Facility Stage-Discharge Primary 394- 393- . d c - 0 Tr", 392- > m - w 391- 390 0 2 41 6 8 10 12 14 16 18 20 221 24 26 Discharge (cfs) Post-Developed Type 1124-hr 100 YR Rainfall=9.13" Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 24 Pond 3P: Modified SWM Facility Stage-Area-Storage Surface Honzontal Wetted Area(sq-ft) 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500 112 Surface Storage 394- 393- - 94-393-- c - 0 '= 392- iu - tu - 391- 390 0 2,000 '4,000' 6,000 '8,000' 10,000 12,000 14,000 Storage(cubic-feet) Post-Developed Type /l 24-hr 100 YR Rainfall=9.13" Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 25 Hydrograph for Pond 3P: Modified SWM Facility Time Inflow Storage Elevation Primary (hours) (cfs) (cubic-feet) (feet) (cfs) 0.00 0.00 0 390.00 0.00 0.50 0.00 0 390.00 0.00 1.00 0.00 0 390.00 0.00 1.50 0.00 0 390.00 0.00 2.00 0.00 0 390.00 0.00 2.50 0.00 0 390.00 0.00 3.00 0.00 0 390.00 0.00 3.50 0.00 0 390.00 0.00 4.00 0.00 0 390.00 0.00 4.50 0.02 17 390.01 0.00 5.00 0.05 80 390.04 0.01 5.50 0.09 181 390.09 0.02 6.00 0.12 293 390.14 0.06 6.50 0.16 396 390.18 0.11 7.00 0.20 483 390.22 0.16 7.50 0.24 558 390.26 0.20 8.00 0.29 624 390.29 0.25 8.50 0.35 695 390.32 0.30 9.00 0.47 807 390.37 0.40 9.50 0.56 933 390.42 0.51 10.00 0.67 1,028 390.46 0.60 10.50 0.91 1,203 390.54 0.78 11.00 1.30 1,486 390.66 1.10 11.50 2.12 1,982 390.86 1.72 12.00 17.80 7,488 392.69 8.34 12.50 7.63 7,604 392.72 9.01 13.00 2.58 4,937 391.92 4.51 13.50 1.76 2,582 391.09 2.45 14.00 1.36 1,872 390.81 1.58 14.50 1.12 1,586 390.70 1.22 15.00 1.01 1,452 390.64 1.06 15.50 0.90 1,355 390.60 0.95 16.00 0.79 1,260 390.56 0.84 16.50 0.71 1,170 390.52 0.75 17.00 0.67 1,117 390.50 0.69 17.50 0.63 1,077 390.48 0.65 18.00 0.59 1,039 390.47 0.61 18.50 0.55 1,000 390.45 0.57 19.00 0.51 961 390.43 0.53 19.50 0.47 920 390.42 0.50 20.00 0.43 878 390.40 0.46 Post-Developed Type 1124-hr 100 YR Rainfall=9.13" Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 26 Stage-Discharge for Pond 3P: Modified SWM Facility Elevation Primary Elevation Primary (feet) (cfs) (feet) (cfs) 390.00 0.00 392.60 6.71 390.05 0.01 392.65 7.54 390.10 0.03 392.70 8.49 390.15 0.07 392.75 9.55 390.20 0.13 392.80 10.69 390.25 0.19 392.85 11.93 390.30 0.27 392.90 13.23 390.35 0.36 392.95 14.62 390.40 0.46 393.00 16.07 390.45 0.57 393.05 17.59 390.50 0.69 393.10 19.18 390.55 0.81 393.15 20.83 390.60 0.94 393.20 22.53 390.65 1.08 393.25 22.92 390.70 1.23 393.30 23.26 390.75 1.38 393.35 23.61 390.80 1.53 393.40 23.87 390.85 1.69 393.45 24.11 390.90 1.85 393.50 24.34 390.95 2.01 393.55 24.58 391.00 2.17 393.60 24.81 391.05 2.33 393.65 25.04 391.10 2.48 393.70 25.27 391.15 2.62 393.75 25.49 391.20 2.76 393.80 25.72 391.25 2.88 393.85 25.94 391.30 2.98 393.90 26.16 391.35 3.08 393.95 26.37 391.40 3.26 394.00 26.59 391.45 3.44 394.05 26.80 391.50 3.61 394.10 27.02 391.55 3.77 394.15 27.23 391.60 3.92 394.20 27.44 391.65 4.06 394.25 27.65 391.70 4.14 394.30 27.85 391.75 4.23 391.80 4.31 391.85 4.39 391.90 4.47 391.95 4.55 392.00 4.63 392.05 4.71 392.10 4.78 392.15 4.86 392.20 4.93 392.25 5.00 392.30 5.07 392.35 5.14 392.40 5.21 392.45 5.28 392.50 5.48 392.55 6.01 Post-Developed Type 1124-hr 100 YR Rainfall=9.13" Prepared by Timmons Group Printed 8/2/2017 HydroCAD® 10.00-19 s/n 06538 ©2016 HydroCAD Software Solutions LLC Page 27 Stage-Area-Storage for Pond 3P: Modified SWM Facility Elevation Surface Storage Elevation Surface Storage (feet) (sq-ft) (cubic-feet) (feet) (sq-ft) (cubic-feet) 390.00 2,107 0 392.60 3,509 7,162 390.05 2,131 106 392.65 3,543 7,339 390.10 2,154 213 392.70 3,578 7,517 390.15 2,178 321 392.75 3,612 7,696 390.20 2,202 431 392.80 3,647 7,878 390.25 2,226 542 392.85 3,681 8,061 390.30 2,249 653 392.90 3,716 8,246 390.35 2,273 766 392.95 3,750 8,433 390.40 2,297 881 393.00 3,785 8,621 390.45 2,320 996 393.05 3,832 8,811 390.50 2,344 1,113 393.10 3,879 9,004 390.55 2,368 1,231 393.15 3,926 9,199 390.60 2,391 1,350 393.20 3,973 9,397 390.65 2,415 1,470 393.25 4,020 9,597 390.70 2,439 1,591 393.30 4,066 9,799 390.75 2,463 1,714 393.35 4,113 10,003 390.80 2,486 1,837 393.40 4,160 10,210 390.85 2,510 1,962 393.45 4,207 10,419 390.90 2,534 2,088 393.50 4,254 10,631 390.95 2,557 2,216 393.55 4,301 10,845 391.00 2,581 2,344 393.60 4,348 11,061 391.05 2,607 2,474 393.65 4,395 11,279 391.10 2,632 2,605 393.70 4,442 11,500 391.15 2,658 2,737 393.75 4,489 11,724 391.20 2,684 2,870 393.80 4,535 11,949 391.25 2,709 3,005 393.85 4,582 12,177 391.30 2,735 3,141 393.90 4,629 12,407 391.35 2,761 3,279 393.95 4,676 12,640 391.40 2,786 3,417 394.00 4,723 12,875 391.45 2,812 3,557 394.05 4,736 13,111 391.50 2,838 3,699 394.10 4,749 13,349 391.55 2,863 3,841 394.15 4,761 13,586 391.60 2,889 3,985 394.20 4,774 13,825 391.65 2,914 4,130 394.25 4,787 14,064 391.70 2,940 4,276 394.30 4,800 14,303 391.75 2,966 4,424 391.80 2,991 4,573 391.85 3,017 4,723 391.90 3,043 4,875 391.95 3,068 5,027 392.00 3,094 5,182 392.05 3,129 5,337 392.10 3,163 5,494 392.15 3,198 5,653 392.20 3,232 5,814 392.25 3,267 5,977 392.30 3,301 6,141 392.35 3,336 6,307 392.40 3,370 6,474 392.45 3,405 6,644 392.50 3,440 6,815 392.55 3,474 6,988 I I I I Project Name: Scottsville Elementary Addtion CLEAR ALL data input cells Date: 3/30/2018 (Ctrl+Shlft+R) constant values Linear Development Project? No I calculation cells Site Information I I final results Post-Development Project(Treatment Volume and Loads) Enter Total Disturbed Area(acres) -4 0.61 Check: 1 BMP Design Specifications List: 2013 Draft Stds&Specs Maximum reduction required: 10% Linear project? No The site's net increase in impervious cover(acres)is: 0.12 Land cover areas entered correctly? ve Post-Development TP Load Reduction for Site(Ib/yr): 0.26 Total disturbed area entered? ye Pre-ReDevelopment Land Cover (acres) A Soils B Soils C Soils D Soils Totals Forest/Open Space(acres)--undisturbed, protected forest/open space or reforested land, 0.00 Managed Turf(acres)--disturbed,graded for yards or other turf to be mowed/managed 0.46 0.46 Impervious Cover(acres) 0.15 0.15 0.61 I Post-Development Land Cover (acres) A Soils B Soils C Soils D Soils Totals Forest/Open Space(acres)--undisturbed, 0.00 protected forest/open space or reforested land Managed Turf(acres)--disturbed,graded for yards or other turf to be mowed/managed 0.34 0.34 Impervious Cover(acres) 0.27 0.27 Area Check OK. OK. OK. OK. 0.61 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 LAND COVER SUMMARY-- PRE-REDEVELOPMENT LAND COVER SUMMARY--POST DEVELOPMENT Land Cover Summary-Pre Land Cover Summary-Post(Final) Land Cover Summary-Post Land Cover Summary-Post Pre-ReDevelopment Listed Adjusted' Post ReDev.&New Impervious Post-ReDevelopment Post-Development New Impervious Forest/Open Space Cover(acres) 0.00 0.00 Forest/Open Space 0.00 Forest/Open Space 0.00 Cover(acres) Cover(acres) Weighted Rv(forest) 0.00 0.00 Weighted Rv(forest) 0.00 Weighted Rv(forest) 0.00 %Forest 0% 0% %Forest 0% %Forest 0% Managed Turf Cover(acres) 0.46 0.34 Managed Turf Cover 0.34 Managed Turf Cover 0.34 (acres) (acres) Weighted Rv(turf) 0.22 0.22 Weighted Rv(turf) 0.22 Weighted Rv(turf) 0.22 %Managed Turf 75% 69% %Managed Turf 56% %Managed Turf 69% Impervious Cover ReDev.Impervious New Impervious Cover Impervious Cover(acres) 0.15 0.15 0.27 0.15 0.12 (acres) Cover(acres) (acres) Rv(impervious) 0.95 0.95 Rv(impervious) 0.95 Rv(impervious) 0.95 Rv(impervious) 0.95 %Impervious 25% 31% %Impervious 44% %Impervious 31% Total Site Area(acres) 0.61 0.49 Final Site Area(acres) 0.61 Total ReDev.Site Area 0.49 • (acres) Site Rv 0.40 0.44 Final Post Dev Site Rv 0.54 ReDev Site Rv 0.44 Treatment Volume and Nutrient Load Treatment Volume and Nutrient Load Final Post- Post-ReDevelopment Post-Development Pre-ReDevelopment Treatment Volume Development (acre-ft) 0.0203 0.0181 Treatment Volume 0.0276 Treatment Volume 0.0181 Treatment Volume 0.0095 (acre-ft) (acre-ft) (acre-ft) Final Post- Pee-ReDevelopment Treatment Volume Development Post-ReDevelopment Post-Development (cubic feet) 885 789 Treatment Volume 1,203 Treatment Volume 789 Treatment Volume(cubic 414 (cubic feet) (cubic feet) feet) •Pre-ReDevelopment TP Load Final Post- Post-ReDevelopment 0.56 0.50 Development TP Load 0.76 Load(TP) 0.50 Post-Development TP 0.26 (Ib/yr) Load(lb/yr) (lb/yr) (Ib/yr)" rest-Developmen'iI' 1,n,t R„D,•v,•i„r.mr•ni IP Pre-ReDevelopment TP Load per acre (Ib/acre/yr) 0.91 1.01 Load per acre 1.24 I„ad p,".1,, 1.01 (lb/acre/yd (lb/acre/yr) Baseline TP Load Ilb/yr) • Mar.Reduction Required (0.41 lbs/acre/yr applied to pre-redevelopment area excluding pervious 0.20 (Below Pre- 10% land proposed for new impervious cover) ' ReDevelopment Load) I II IT Load Reduction Adjusted Land Cover Summary: TP Load Reduction Pre ReDevelopment land cover minus pervious land cover(forest/open space or Required for managed turf)acreage proposed for new impervious cover. Redeveloped Area 0.05 Required for New 0.21 (Ib/yr) Impervious Area(Ib/yr) 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 loud limit.0.41 lbs/Here/yeorI. Post-Development Requirement for Site Area TP Load Reduction Required(Ib/yr) 0.26 RECEI\; COMMUNI1 Y DEVELOPMENT