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HomeMy WebLinkAboutWPO201400022 Calculations Stormwater Management Plan 2014-03-06 STORMWATER MANAGEMENT AND BEST MANAGEMENT PRACTICES AT&T SITE NUMBER CV327B ALBEMARLE COUNTY, VIRGINIA March 6, 2014 Prepared for: architectsC engineers BC Architects Christopher D. Morin, PE 5661 Columbia Pike, Suite 200 Falls Church, VA 22041 Tel: 703-671-6000 Prepared by: Painter-Lewis, P.L.C. Consulting Engineers 817 Cedar Creek Grade, Suite 120 Winchester, VA 22601 Tel: 540-662-5792 Fax: 540-662-5793 Email:office@painterlewis.com -- • JOHN V C i k _ l s ALBEMARLE COUNTY CV327B SWM/BMP Table of Contents SITE AND PROJECT DESCRIPTION Page 3 SITE SOILS Page 3 FLOOD PLAIN INFORMATION Page 3 ACCESC ROAD CULVERTS Page 3 WATER QUALITY Page 4 EXHIBITS Page 5 page 2 ALBEMARLE COUNTY CV327B SWM/BMP SITE AND PROJECT DESCRIPTION The proposed development for this site includes the construction of a 31 foot by 50 foot cell tower pad site and a gravel access drive to the pad site for a 92' monopole. The site is located on a 43 acre parcel under the ownership of Verulam Farm Limited Partnership and is currently vacant. The parcel is partially wooded with active culti- vated areas. Access to the site will come from Dick Woods Road. The site of the ac- cess road and tower pad slopes moderately from north to south. Drainage from the site flows in natural channels under Dick Woods Road and into Ivy Creek. Ivy Creek is a tributary of the South Fork Rivanna River and as such the site lays within the Wa- ter Supply Protection Area. The limits of disturbance required for this construction consist of an area of approxi- mately 33,800 sf(0.78 acres)with 20,700 sf(0.48 acres) of proposed gravel surfaces. The road generally follows an existing farm road. Effort will be made to conduct the construction using low impact methods, including limiting the amount of disturbed area, preserving existing trees, and locating the access road to disrupt the existing runoff character of the site as little as practicable, that is, to maintain the existing run- off flow patterns. The access road crosses three drainage swales. There is an existing culvert at the entrance to the site plus two crossings along the proposed access road alignment. Each of these three crossings have been analyzed for the 10 year-24 hour storm event and the performance of the existing culvert and the two proposed culverts. SITE SOILS The predominant soil types within the in the watersheds which contribute runoff to the access road crossings are Ashe loam, Braddock loam, Chester loam, Cullen loam, Dyke silt loam, Hayesville loam, Meadowville loam, Parker very stony loam, River- view-Chewacla complex, and Toccoa fine loam. With the exception of Cullen loarns, these soils are in Hydrologic Soils Group B in accordance with the USDA soil textural classification. The soils map and information is contained in Exhibit 1. FLOOD PLAIN INFORMATION The FEMA Flood Insurance Rate Map #51003CO265D shows that the unnamed tribu- tary to Ivy Creek at the Culvert#3 crossing likely within Zone A. The remainder of the site is not within a designated Special Flood Hazard Area. A facsimile of the FIRM is contained in Exhibit 2. ACCESS ROAD CULVERTS The access road will be located generally along the alignment of an existing farm road. The selected location of the road will maintain current drainage patterns. The access road will have minimal effect on the concentration of storm water as it passes through the parcel. There are currently, well defined drainage swales where the pro- posed culverts will be located. The peak flow to each culvert crossing was calculated page 3 ALBEMARLE COUNTY CV327B SWM/BMP by the SCS 10 year-24 hour storm method and each culvert was sized accordingly. The exit velocity of the storm water from the culverts will be dissipated by the place- ment of rip rap at the outlets to achieve non-erosive velocities. Exhibit 3 contains a drainage area map showing the contributing drainage area for each of the three crossings. Rainfall depths for the 2 year (3.68"), 10 year (5.56"), and 100 year (9.1") storms were taken from the NOAA Atlas 14, Volume 2, Version 3 for Charlottesville, VA, Exhibit 4 contains the results of the SCS Unit Hydrograph Model and peak dis- charge rates for each of the three contributing watersheds. Using the peak discharge rates, the appropriate culvert(s) size was determined. Exhibit 5 contains the analyses of the performance of each culvert during the 10 year-24 hour storm followed by an analysis of the exit velocity of the exit rip rap. Refer to Exhibit 6 for a typical rip rap outfall detail and associated sizing nomograph. The results are summarized in the fol- lowing table. DESCRIPTION Q10 CULVERT RIP RAP EXIT NO. (cfs) VELOCITY (fps) VELOCITY(fps) 1 24'-24" dia. CMP @1.67% 13.4 6.1 2.76 2 42'-24" dia. CMP @1.19% 21.2 7.65 3.26 3 (2)36'-36" dia. CMP @1.39% 94.9 6.95 4.71 Water Quality In accordance with the Virginia Department of Environmental Quality, Performance- Based Water Quality Computations, there is no requirement for water quality devices for this site. Please refer to the worksheet contained in Exhibit 7. page 4 [ 1 ALBEMARLE COUNTY CV327B SWM/BMP EXHIBITS: EXHIBIT 1 SOILS INFORMATION EXHIBIT 2 FEMA FIRMETTE EXHIBIT 3 DRAINAGE AREA MAP EXHIBIT 4 PEAK FLOW DATA EXHIBIT 5 CULVERT PERFORMANCE DATA EXHIBIT 6 OUTLET CONTROL DESIGN AND RIP RAP NOMOGRAPH EXHIBIT 7 PERFORMANCE-BASED WATER QUALITY COMPUTATIONS page 5 , ALBEMARLE COUNTY CV327B SWM/BMP EXHIBIT 1 SOILS INFORMATION page 6 3 Soil Map—Albemarle County,Virginia R k k* 709000 709200 709400 709600 709800 710000 710200 38°2'47N irr, q 38'2'47N a N a g 14C 4D 14C / 36B �t 4D C * 37D3 �',- a 56B 37C 3 �v- 4`1 I :- 360 ) /--/4D .Al _.----- 3 7 0 3 --/ � r' ` , 66E 140 " m *;1♦�!�ny� 1 �.f� / p w...l' `� • ,I....' ' , . 37B3'7 '19B 14 { `56B ti` v 'B fir. \,2C ., 37G3 3703 =-- r ay. a soF3 64 i H F i � .. T. "3703 3703 f Ter f 6--tit,,,,,, 7 3703/ - , it 1 n ,, `W-.,, ,.r • • st r,. r V # 703 �� �. 37,G ' , .'j r is - ' NP r4711 I _1 1 3r 2.47'N 709000 709200 709400 709600 709800 710000 710200 3 0 3 ill M Map Sole:1:8,990 it printed on A portrait(8.5"x 11")sheet Meters k N o 100 200 400 6 0 A 0 400 800 Feet 1600 2400 Map Pr01e<bon:Web Merotnr Comer coordarates:WGS84 Edge tis:U1M Zone 17N WGS84 Mi& Natural Resources Web Soil Survey 3/6/2014 Conservation Service National Cooperative Soil Survey Page 1 of 3 l f Soil Map—Albemarle County,Virginia MAP LEGEND MAP INFORMATION Area of Interest IAO/) Spot Area The soil surveys that comprise your AO1 were mapped at 1:15,800. El Area of Interest(AOl) Q Stony Spot Please rely on the bar scale on each map sheet for map Seib measurements. eb Vary Stony Spot Sol Map Unit Polygons Source of Map: Natural Resources Conservation Service ...r Sod Map Una es YYst Spot LinWeb Soil Survey URL httpi/websoilsurv.y.nres.usda.gov Other Coordinate System: Web Mercator(EPSG:3857) Soil Map Una Points Special Point Features Special Line Features Maps from the Web Soil Survey are based on the Web Mercator Water Features projection,which preserves direction and shape but distorts V Blowoutdistance and area.A projection that preserves area,such as the Streams and Canals Abets• al-area conic El Bonar Ps projection,er should be used if more accurate Transportation calculationsarea of distance or area are required. X Clay Spa ~* Rads This product is generated from the USDA-MRCS certified data as of Closed Depression ry Interstate Highways the version date(s)listed below. v Gravel Pit US Routes Soil Survey Area: Alamarle County,Virginia Gravelly Spot Survey Area Data: Version 10,Dec 11.2013 Major Roads lands Sod map units are labeled(as space allows)formap scales 1:50,000 Local Roads or larger. Lava Flow Background Date(s)aerial images were photographed. May 10,2010—Jun 4. Marsh or swamp Aerial Photography 2011 Mina or Quarry The orthophoto or other base map on which the soil lines were Miscellaneous Water compiled and digitized probably differs from the background Perennial Water imagery displayed on these maps.As a result,some minor shiling of map unit boundaries may be evident Rock Outcrop + Seine Spot Sandy Spot Severely Eroded Spot ,: Sinkhole Side or Sep Sodk Spot UiSD.t Natural Resources Web Soil Survey 3/8/2014 Il Conservation Service National Cooperative Soil Survey Page 2 of 3 Soil Map-Albemarle County,Virginia Map Unit Legend Albemarle County,Virginia(VA003) Map Unit Symbol Map Unit Name Acres In AOI Percent of AOI 4D Ashe loam,15 to 25 percent 34.2 9.5% a slopes 4E Ashe loam,25 to 45 percent 5.5 1.5% slopes 78 ! Braddock loam,2 to 7 percent 30.3 8.4% slopes 7C Braddodc loam,7 to 15 percent 9.0 2.5% slopes 14C 12 Chester loam,7 to 15 percent 3.3 0.9% slopes Y 19B ,- Cullen loam,2 to 7 percent 5.5 1.5% slopes 19C Cullen loam,7 to 15 percent 8.3 2.3% slopes 20C3 Cullen clay loam,7 to 15 6.0 1.7% percent slopes,severely eroded 25B 11 Dyke silt loam,2 to 7 percent 15.04.2% slopes 36B \--4 Hayesville loam,2 to 7 percent 40.7 11.3% slopes ~ 36C Hayesville loam,7 to 15 percent 28.2 7.8% slopes J 37B3 Hayesville clay loam,2 to 7 4.1 1.1% percent slopes,severely eroded 37C3 Hayesville clay loam,7 to 15 77.0 21.4% percent slopes,severely eroded 3703 Hayesville clay loam,15 to 25 48.9 13.6% percent slopes,severely eroded 56B ¶` Meadowville loam,2 to 7 16.5 4.6% percent slopes 66E U Parker very stony loam,25 to 45 1.6 0.4% percent slopes 77 k3 Riverview-Chewaca complex 21.3 5.9% 83 3 Toccoa fine sandy loam 4.2 1.2% Totals for Area of Interest 359.4 100.0% USDA Natural Resources Web Soil Survey 3/6/2014 2111. Conservation Service National Cooperative Soil Survey Page 3 of 3 1 1 ALBEMARLE COUNTY CV327B SWM/BMP EXHIBIT 2 FEMA FIRMETTE page 7 d§, CI vo�d [ ! co7. E0'c c W 4 tZ�� D d o lit M� W= t • gLLi W I^ gco, 0 E I CO N N `o a I— 2 W C7 3 J 2%1 =v W� d oz.. L.., — N E., W Li 1 i s b z f., ?� u 12 o $a sC " 4 w zz o"o E.- S u g$a N' u, W ° cli .a a se 3E0 W= u !smog o z � Edd' a5 LL B 00 W L" "° OG4a7 W 1 EELL NC e g� d� W U O $' % `o_cgzw g co� A 7 ' C Ce 0 ih 1111 w le v 2 8u.E \v�r J _ o E Q aWcy; C.) t�Eam I • �t$ 2 ` Y a Ill A...0) y/' v_ / W 3 Q ,.f 4 N ";444c, ' / 2 . ov, SFPP w itO ft g / 2 We s = 3 ,, I EV . _ . 4747 Z o o ` 11 011 , cc 2 . ' 1-r, l. . z z4 0 O -_ CC 1Z Aom` oa Yuj IN Y JG\ N gx -ht + QO to Ks.caz 14( , i 19\ , 0 1 1 r o z a Ni Nlddld a cc O on g\\,) , O J /1 \ Y7 F ALBEMARLE COUNTY CV327B SWM/BMP EXHIBIT 3 DRAINAGE AREA MAP page 8 '''•••••—'V rd'Wegirfr:i IN0rrr- /).14 711,9 •;. 7.80 fT9Z ,//•t�=$ % ....________/,}\:_r:..i fir ,atia $�6. ` �, i*,=,54)- -;S:t\ . c c c c c , ) ' r•-„ .4: r: --6‘1,- .-41. :07.._,Ams"i'r... 0...\ ,,\',,L, , ,6:_,,,,, F, ,, ), • •111"- rNmet44141%\IMATi N.? 13. 680.4 ;i1;:if ,t ipl'cii4(t , .‘ */) c-- 4 bt°‘ - '-.76/61t a �� � ---� :.. ►" •��- �:��-•---,/ 668 ft _...- ft.____,..-/60' 0....,. .._...,,iW-7%,,s/411 % J _ ,-1, . , `/ m,tO 6 4 N '1 ,i• Ski: •21-- d, 620 ft : ., n t 68 tit \ ib t� •� AP.V.:; l io fD . ``. 60 ill s;?1,1t 6_4.0. • � '600, Kr rel 4 �-� co <° sct 6271 8 tl` <648 ;, ((/t M. 592+tt _ teltEWA. 4 / tZ.... 6°4, / 624th 32 ft 0.24 ft .�64.10 r:r/'�� ;62. tt;'� 640_ft •20 ft 636 . �r <62ft1,,`�` �6a0:n'6a�'� �7�/�628itt, J<<`L 3f3 sg6Qtn' .,� 649 f1 656 ft 1 'ick - 624 it AlL17,„eatillii,)*---: .„,,,,,.. -"---- ___ til --vommommollp, / e""--"ea %'", , AV... ..,4411.104N -- 1 Nitrario a .�.or -.4.4592111L....---...k\\\' - ‘,c. 0, s� • \., % i �:1 S�Alit` : •r S_.: 87 8�rt � �J/! ,' 600=ft ate:`. �L ____ �1v W6�lu«'1 �. DRAINAGE AREA 13 DRAINAGE AREA #2 DRAINAGE AREA #1 104 ACRES 23 ACRES 10.6 ACRES Tc LENGTH-3.454' Tc LENGTH.2,120' Tc LENGTH•1.060' Q10.194.9 CFS Q10.21.2 CFS Q10-13.4 CFS 500 0 500 PROJECT: SURVEY: C : MI DRAINAGE AREA MAP 'SCO 4'ii ' SITE NUMBER CV327B SCALE: DATE: ALBEMARLE COUNTY, VIRGINIA SHOWN 3/5/14 Scale in Feet SHEET: DAM t t ALBEMARLE COUNTY CV327B SWM/BMP EXHIBIT 4 PEAK FLOW DATA page 9 Type. . . . Master Network Summary Page 1.01 Name. . . . Watershed File. . . . C:\John Lewis\PEAK RUNOFF RATES DAI.PPW MASTER DESIGN STORM SUMMARY Network Storm Collection: Charlottsville V Total Depth Rainfall Return Event in Type RNF ID 2 3.6800 Synthetic Curve TypeII 24hr 10 5.5600 Synthetic Curve Typell 24hr 100 9.1000 Synthetic Curve TypeII 24hr MASTER NETWORK SUMMARY SCS Unit Hydrograph Method (*Node=Outfall; +Node=Diversion;) (True= HYG Truncation: Blank=None; L=Left; R=Rt; LR=Left&Rt) Max Return HYG Vol Qpeak Qpeak Max WSEL Pond Storage Node ID Type Event ac-ft Trun hrs cfs ft ac-ft DA 1 AREA 2 .540 12.2500 3.95 DA 1 AREA 10 1.449 12.2000 13.43 DA 1 AREA 100 3.692 12.2000 37.01 *OUT 10 JCT 2 .540 12.2500 3.95 *OUT 10 JCT 10 1.449 12.2000 13.43 *OUT 10 JCT 100 3.692 12.2000 37.01 S/N: 021701607007 Painter-Lewis PondPack Ver. 09.00.077.00 Time: 9:58 AM Date: 3/7/2014 • Type. . . . Tc Calcs Page 2.01 Name. . . . DA 1 File. . . . C:\John Lewis\PEAK RUNOFF RATES DAI.PPW TIME OF CONCENTRATION CALCULATOR Segment #1: Tc: TR-55 Sheet Mannings n .4000 Hydraulic Length 300.00 ft 2yr, 24hr P 3.6800 in Slope .093000 ft/ft Avg.Velocity .19 ft/sec Segment #1 Time: .4346 hrs Segment #2: Tc: TR-55 Shallow Hydraulic Length 450.00 ft Slope .088000 ft/ft Unpaved Avg.Velocity 4.79 ft/sec Segment #2 Time: .0261 hrs Segment #3: Tc: TR-55 Channel Flow Area 1.3000 sq.ft Wetted Perimeter 5.10 ft Hydraulic Radius .25 ft Slope .035000 ft/ft Mannings n .0450 Hydraulic Length 310.00 ft Avg.Velocity 2.49 ft/sec Segment #3 Time: .0346 hrs Total Tc: .4953 hrs S/N: 021701607007 Painter-Lewis PondPack Ver. 09.00.077.00 Time: 9:58 AM Date: 3/7/2014 t i Type. . . . Tc Caics Page 2.02 Name. . . . DA 1 File. . . . C:\John Lewis\PEAK RUNOFF RATES DAI.PPW Tc Equations used. . . ___= SCS TR-55 Sheet Flow Tc = (.007 * ( (n * Lf)**0.8) ) / ( (P**.5) * (Sf**.4)) Where: Tc = Time of concentration, hrs n = Mannings n Lf = Flow length, ft P = 2yr, 24hr Rain depth, inches Sf = Slope, SCS TR-55 Shallow Concentrated Flow Unpaved surface: V = 16.1345 * (Sf**0.5) Paved surface: V = 20.3282 * (Sf**0.5) Tc = (Lf / V) / (3600sec/hr) Where: V = Velocity, ft/sec Sf = Slope, ft/ft Tc = Time of concentration, hrs Lf = Flow length, ft S/N: 021701607007 Painter-Lewis PondPack Ver. 09.00.077.00 Time: 9:58 AM Date: 3/7/2014 Type. . . . Tc Calcs Page 2.03 Name. . . . DA 1 File. . . . C:\John Lewis\PEAK RUNOFF RATES DAI.PPW ___= SCS Channel Flow R = Aq / Wp V = (1.49 * (R**(2/3)) * (Sf**-0.5) ) / n Tc = (Lf / V) / (3600sec/hr) Where: R = Hydraulic radius Aq = Flow area, sq.ft. Wp = Wetted perimeter, ft V = Velocity, ft/sec Sf = Slope, ft/ft n = Mannings n Tc = Time of concentration, hrs Lf = Flow length, ft • S/N: 021701607007 Painter-Lewis PondPack Ver. 09.00.077.00 Time: 9:58 AM Date: 3/7/2014 Type. . . . Runoff CN-Area Page 3.01 Name. . . . DA 1 File. . . . C:\John Lewis\PEAK RUNOFF RATES DAI.PPW RUNOFF CURVE NUMBER DATA Impervious Area Adjustment Adjusted Soil/Surface Description CN acres %C %UC CN Woods - good 55 2.000 55.00 Impervious Areas - Gravel (w/ right 85 .100 85.00 Impervious Areas - Paved parking l0 98 .500 98.00 Meadow - cont. grass (non grazed) - 58 8.000 58.00 COMPOSITE AREA & WEIGHTED CN ---> 10.600 59.58 (60) S/N: 021701607007 Painter-Lewis PondPack Ver. 09.00.077.00 Time: 9:58 AM Date: 3/7/2014 . • Type. . . . Master Network Summary Page 1.01 Name. . . . Watershed File. . . . C:\John Lewis\PEAK RUNOFF RATES DA2.PPW MASTER DESIGN STORM SUMMARY Network Storm Collection: Charlottsville V Total Depth Rainfall Return Event in Type RNF ID 2 3.6800 Synthetic Curve Typell 24hr 10 5.5600 Synthetic Curve TypeII 24hr 100 9.1000 Synthetic Curve TypeII 24hr MASTER NETWORK SUMMARY SCS Unit Hydrograph Method (*Node=Outfall; +Node=Diversion;) (Trun= HYG Truncation: Blank=None; L=Left; R=Rt; LR=Left&Rt) Max Return HYG Vol Qpeak Qpeak Max WSEL Pond Storage Node ID Type Event ac-ft Trun hrs cfs ft ac-ft DA 2 AREA 2 1.088 12.4500 5.93 DA 2 AREA 10 2.999 12.3500 21.21 DA 2 AREA 100 7.775 12.3500 60.68 *OUT 10 JCT 2 1.088 12.4500 5.93 *OUT 10 JCT 10 2.999 12.3500 21.21 *OUT 10 JCT 100 7.775 12.3500 60.68 S/N: 021701607007 Painter-Lewis PondPack Ver. 09.00.077.00 Time: 10:04 AM Date: 3/7/2014 Type. . . . Tc Calcs Page 2.01 Name. . . . DA 2 File. . . . C:\John Lewis\PEAK RUNOFF RATES DA2.PPW TIME OF CONCENTRATION CALCULATOR Segment #1: Tc: TR-55 Sheet Mannings n .4000 Hydraulic Length 300.00 ft 2yr, 24hr P 3.6800 in Slope .040000 ft/ft Avg.Velocity .14 ft/sec Segment #1 Time: .6091 hrs Segment #2: Tc: TR-55 Shallow Hydraulic Length 800.00 ft Slope .060000 ft/ft Unpaved Avg.Velocity 3.95 ft/sec Segment #2 Time: .0562 hrs Segment #3: Tc: TR-55 Channel Flow Area 6.0000 sq.ft Wetted Perimeter 13.00 ft Hydraulic Radius .46 ft Slope .060000 ft/ft Mannings n .0450 Hydraulic Length 1020.00 ft Avg.Velocity 4.84 ft/sec Segment #3 Time: .0585 hrs Total Tc: .7238 hrs S/N: 021701607007 Painter-Lewis PondPack Ver. 09.00.077.00 Time: 10:04 AM Date: 3/7/2014 Type. . . . Tc Calcs Page 2.02 Name. . . . DA 2 File. . . . C:\John Lewis\PEAK RUNOFF RATES DA2.PPW Tc Equations used. . . ___= SCS TR-55 Sheet Flow Tc = (.007 * ( (n * Lf)**0.8) ) / ( (P**.5) * (Sf**.4) ) Where: Tc = Time of concentration, hrs n = Mannings n Lf = Flow length, ft P = 2yr, 24hr Rain depth, inches Sf = Slope, % ___= SCS TR-55 Shallow Concentrated Flow Unpaved surface: V = 16.1345 * (Sf**0.5) Paved surface: V = 20.3282 * (Sf**0.5) Tc = (Lf / V) / (3600sec/hr) Where: V = Velocity, ft/sec Sf = Slope, ft/ft Tc = Time of concentration, hrs Lf = Flow length, ft S/N: 021701607007 Painter-Lewis PondPack Ver. 09.00.077.00 Time: 10:04 AM Date: 3/7/2014 Type. . . . Tc Calcs Page 2.03 Name. . . . DA 2 File. . . . C:\John Lewis\PEAK RUNOFF RATES DA2.PPW ___= SCS Channel Flow -- R = Aq / Wp V = (1.49 * (R**(2/3)) * (Sf**-0.5) ) / n Tc = (Lf / V) / (3600sec/hr) Where: R = Hydraulic radius Aq = Flow area, sq.ft. Wp = Wetted perimeter, ft V = Velocity, ft/sec Sf = Slope, ft/ft n = Mannings n Tc = Time of concentration, hrs Lf = Flow length, ft S/N: 021701607007 Painter-Lewis PondPack Ver. 09.00.077.00 Time: 10:04 AM Date: 3/7/2014 Type. . . . Runoff CN-Area Page 3.01 Name. . . . DA 2 File. . . . C:\John Lewis\PEAK RUNOFF RATES DA2.PPW RUNOFF CURVE NUMBER DATA Impervious Area Adjustment Adjusted Soil/Surface Description CN acres %C %UC CN Woods - good 55 7.000 55.00 Impervious Areas - Gravel (w/ right 85 .500 85.00 Impervious Areas - Paved parking lo 98 .700 98.00 Meadow - cont. grass ;non grazed) - 58 14.800 58.00 COMPOSITE AREA & WEIGHTED CN ---> 23.000 58.89 (59) S/N: 021701607007 Painter-Lewis PondPack Ver. 09.00.077.00 Time: 10:04 AM Date: 3/7/2014 it Type. . . . Master Network Summary Page 1.01 Name. . . . Watershed File. . . . C:\John Lewis\CV237B Abemarle County\PEAK RUNOFF RATES DA3.PPW MASTER DESIGN STORM SUMMARY Network Storm Collection: Charlottsville V Total Depth Rainfall Return Event in Type RNF ID 2 3.6800 Synthetic Curve Typell 24hr 10 5.5600 Synthetic Curve Typell 24hr 100 9.1000 Synthetic Curve Typell 24hr MASTER NETWORK SUMMARY SCS Unit Hydrograph Method (*Node=Outfall; +Node=Diversion;) (Trun= HYG Truncation: Blank=None; L=Left; R=Rt; LR=Left&Rt) Max Return HYG Vol Qpeak Qpeak Max WSEL Pond Storage Node ID Type Event ac-ft Trun hrs cfs ft ac-ft DA 3 AREA 2 4.556 12.4000 24.75 DA 3 AREA 10 12.905 12.3500 94.90 DA 3 AREA 100 34.069 12.3000 278.39 *OUT 10 JCT 2 4.556 12.4000 24.75 *OUT 10 JCT 10 12.905 12.3500 94.90 *OUT 10 JCT 100 34.069 12.3000 278.39 S/N: 021701607007 Painter-Lewis PondPack Ver. 09.00.077.00 Time: 10:52 AM Date: 3/7/2014 i r Type. . . . Tc Calcs Page 2.01 Name. . . . DA 3 File. . . . C:\John Lewis\CV237B Abemarle County\PEAK RUNOFF RATES DA3.PPW TIME OF CONCENTRATION CALCULATOR Segment #1: Tc: TR-55 Sheet Mannings n .4000 Hydraulic Length 120.00 ft 2yr, 24hr P 3.6800 in Slope .020000 ft/ft Avg.Velocity .09 ft/sec Segment #1 Time: .3861 hrs Segment #2: Tc: TR-55 Sheet Mannings n .0400 Hydraulic Length 200.00 ft 2yr, 24hr P 3.6800 in Slope .080000 ft/ft Avg.Velocity 1.05 ft/sec Segment #2 Time: .0529 hrs Segment #3: Tc: TR-55 Shallow Hydraulic Length 800.00 ft Slope .120000 ft/ft Unpaved Avg.Velocity 5.59 ft/sec Segment #3 Time: .0398 hrs S/N: 021701607007 Painter-Lewis PondPack Ver. 09.00.077.00 Time: 10:52 AM Date: 3/7/2014 r Type. . . . Tc Calcs Page 2.02 Name. . . . DA 3 File. . . . C:\John Lewis\CV237B Abemarle County\PEAK RUNOFF RATES DA3.PPW Segment #4: Tc: TR-55 Channel Flow Area 1.5000 sq.ft Wetted Perimeter 6.00 ft Hydraulic Radius .25 ft Slope .060000 ft/ft Mannings n .0450 Hydraulic Length 1400.00 ft Avg.Velocity 3.22 ft/sec Segment #4 Time: .1208 hrs Segment #5: Tc: TR-55 Channel Flow Area 22.5000 sq.ft Wetted Perimeter 30.00 ft Hydraulic Radius .75 ft Slope .021000 ft/ft Mannings n .0450 Hydraulic Length 1025.00 ft Avg.Velocity 3.96 ft/sec Segment #5 Time: .0719 hrs Total Tc: .6715 hrs S/N: 021701607007 Painter-Lewis PondPack Ver. 09.00.077.00 Time: 10:52 AM Date: 3/7/2014 Type. . . . Tc Calcs Page 2.03 Name. . . . DA 3 File. . . . C:\John Lewis\CV237B Abemarle County\PEAK RUNOFF RATES DA3.PPW Tc Equations used. . . ___= SCS TR-55 Sheet Flow Tc = (.007 * ( (n * Lf)**0.8) ) / ( (P**.5) * (Sf**.4) ) Where: Tc = Time of concentration, hrs n = Mannings n Lf = Flow length, ft P = 2yr, 24hr Rain depth, inches Sf = Slope, __-= SCS TR-55 Shallow Concentrated Flow Unpaved surface: V = 16.1345 * (Sf**0.5) Paved surface: V = 20.3282 * (Sf**0.5) Tc = (Lf / V) / (3600sec/hr) Where: V = Velocity, ft/sec Sf = Slope, ft/ft Tc = Time of concentration, hrs Lf = Flow length, ft S/N: 021701607007 Painter-Lewis PondPack Ver. 09.00.077.00 Time: 10:52 AM Date: 3/7/2014 Type. . . . Tc Calcs Page 2.04 Name. . . . DA 3 File. . . . C:\John Lewis\CV237B Abemarle County\PEAK RUNOFF RATES DA3.PPW ___= SCS Charnel Flow R = Aq / Wp V = (1.49 * (R** (2/3) ) * (Sf**-0.5) ) / n Tc = (Lf / V) / (3600sec/hr) Where: R = Hydraulic radius Aq = Flow area, sq.ft. Wp = Wetted perimeter, ft V = Velocity, ft/sec Sf = Slope, ft/ft n = Mannings n Tc = Time of concentration, hrs Lf = Flow length, ft S/N: 021701607007 Painter-Lewis PondPack Ver. 09.00.077.00 Time: 10:52 AM Date: 3/7/2014 Y ALBEMARLE COUNTY CV327B SWM/BMP EXHIBIT 5 CULVERT PERFORMANCE DATA page 10 r Culvert Designer/Analyzer Report Culvert#1 Analysis Component Storm Event Design Discharge 13.40 cfs Peak Discharge Method:User-Specified Design Discharge 13.40 cfs Check Discharge 37.01 cfs Tailwater properties:Irregular Channel Roughness Segments Start End Mannings Station Station Coefficient 0+00 0+08 0.040 0+08 0+16 0.060 0+16 0+20 0.040 Natural Channel Points Station Elevation (ft) (ft) 0+00 566.00 0+08 565.00 0+14 564.50 0+16 565.00 0+18 566.00 0+20 567.00 Tailwater conditions for Design Storm. Discharge 13.40 cfs Actual Depth 0.80 ft Velocity 2.76 ft/s Name Description Discharge HW Elev. Velocity Culvert-1 1-24 inch Circular 13.40 cfs 567.27 ft 6.10 ft/s Weir Not Considered N/A N/A N/A Project Engineer:JOHN LEWIS s:\...\cv327b.cvm PAINTER-LEWIS,PLC CulvertMaster v3.0[3.0004] 03/07/14 11:04:48 AM ©Haestad Methods,Inc. 37 Brookside Road Waterbury,CT 06708 USA +1-203-755-1666 Page 1 of 2 Culvert Designer/Analyzer Report Culvert#1 Component:Culvert-1 Culvert Summary Computed Headwater Elevw 567.27 ft Discharge 13.40 cfs Inlet Control HW Elev. 567.16 ft Tailwater Elevation 565.30 ft Outlet Control HW Elev. 567.27 ft Control Type Outlet Control Headwater Depth/Height 1.18 Grades Upstream Invert 564.92 ft Downstream Invert 564.52 ft Length 24.00 ft Constructed Slope 0.016667 ft/ft Hydraulic Profile Profile M2 Depth,Downstream 1.32 ft Slope Type Mild Normal Depth 1.41 ft Flow Regime Subcritical Critical Depth 1.32 ft Velocity Downstream 6.10 ft/s Critical Slope 0.020102 ft/ft Section Section Shape Circular Mannings Coefficient 0.024 Section Material CMP Span 2.00 ft Section Size 24 inch Rise 2.00 ft Number Sections 1 Outlet Control Properties Outlet Control HW Elev. 567.27 ft Upstream Velocity Head 0.50 ft Ke 0.90 Entrance Loss 0.45 ft Inlet Control Properties Inlet Control HW Elev. 567.16 ft Flow Control Unsubmerged Inlet Type Projecting Area Full 3.1 ft2 K 0.03400 HDS 5 Chart 2 M 1.50000 HDS 5 Scale 3 C 0.05530 Equation Form 1 Y 0.54000 Project Engineer:JOHN LEWIS s:\...\cv327b.cvm PAINTER-LEWIS,PLC CulvertMaster v3.0[3.0004] 03/07/14 11:04:48 AM 0 Haestad Methods,Inc. 37 Brookside Road Waterbury,CT 06708 USA +1-203-755-1666 Page 2 of 2 Culvert Designer/Analyzer Report Culvert#2 Analysis Component Storm Event Design Discharge 21.20 cfs Peak Discharge Method:User-Specified Design Discharge 21.20 cfs Check Discharge 30.70 cfs Tailwater properties:Irregular Channel Roughness Segments Start End Mannings Station Station Coefficient 0+00 0+07 0.040 0+07 0+16 0.060 0+16 0+20 0.040 Natural Channel Points Station Elevation (ft) (ft) 0+00 575.00 0+07 574.00 0+12 573.00 0+16 574.00 0+18 574.50 0+20 575.00 Tailwater conditions for Design Storm. Discharge 21.20 cfs Actual Depth 1.20 ft Velocity 3.26 ft/s Name Description Discharge HW Elev. Velocity Culvert-1 1-24 inch Circular 21.20 cfs 577.42 ft 7.65 ft/s Weir Not Considered N/A N/A N/A Project Engineer:JOHN LEWIS s:1...1cv327b.cvm PAINTER-LEWIS,PLC CulvertMaster v3.0[3.0004] 03/07/14 11:18:23 AM m Haestad Methods,Inc. 37 Brookside Road Waterbury,CT 06708 USA +1-203-755-1666 Page 1 of 2 f y Culvert Designer/Analyzer Report Culvert#2 Component:Culvert-1 Culvert Summary Computed Headwater Elev 577.42 ft Discharge 21.20 cfs Inlet Control HW Elev. 577.09 ft Tailwater Elevation 574.20 ft Outlet Control HW Elev. 577.42 ft Control Type Outlet Control Headwater Depth/Height 1.96 Grades Upstream Invert 573.50 ft Downstream Invert 573.00 ft Length 42.00 ft Constructed Slope 0.011905 ft/ft Hydraulic Profile Profile CompositeM2PressureProfile Depth,Downstream 1.65 ft Slope Type Mild Normal Depth N/A ft Flow Regime Subcritical Critical Depth 1.65 ft Velocity Downstream 7.65 ft/s Critical Slope 0.029630 ft/ft Section Section Shape Circular Mannings Coefficient 0.024 Section Material CMP Span 2.00 ft Section Size 24 inch Rise 2.00 ft Number Sections 1 Outlet Control Properties Outlet Control HW Elev. 577.42 ft Upstream Velocity Head 0.71 ft Ke 0.90 Entrance Loss 0.64 ft Inlet Control Properties Inlet Control HW Elev. 577.09 ft Flow Control Submerged Inlet Type Projecting Area Full 3.1 ft2 K 0.03400 HDS 5 Chart 2 M 1.50000 HDS 5 Scale 3 C 0.05530 Equation Form 1 Y 0.54000 Project Engineer:JOHN LEWIS s:\...\cv327b.cvm PAINTER-LEWIS,PLC CulvertMaster v3.0(3.0004] 03/07/14 11:18:23 AM ©Haestad Methods,Inc. 37 Brookside Road Waterbury,CT 06708 USA +1-203-755-1666 Page 2 of 2 Culvert Designer/Analyzer Report Culvert#3 Analysis Component Storm Event Design Discharge 94.90 cfs Peak Discharge Method:User-Specified Design Discharge 94.90 cfs Check Discharge 278.00 cfs Tailwater properties:Irregular Channel Roughness Segments Start End Mannings Station Station Coefficient 0+00 0+07 0.040 0+07 0+16 0.060 0+16 0+20 0.040 Natural Channel Points Station Elevation (ft) (ft) 0+00 575.00 0+07 574.00 0+12 571.80 0+16 574.00 0+18 574.50 0+20 575.00 Tailwater conditions for Design Storm. Discharge 94.90 cfs Actual Depth 2.97 ft Velocity 4.71 ftls Name Description Discharge HW Elev. Velocity Culvert-1 2-36 inch Circular 94.90 cfs 576.72 ft 6.95 fUs Weir Not Considered N/A N/A N/A Project Engineer:JOHN LEWIS s:\...\cv327b.cvm PAINTER-LEWIS,PLC CulvertMaster v3.0[3.0004] 03/07/14 11:32:53 AM ©Haestad Methods,Inc. 37 Brookside Road Waterbury,CT 06708 USA +1-203-755-1666 Page 1 of 2 1 iI Culvert Designer/Analyzer Report Culvert#3 Component:Culvert-1 Culvert Summary Computed Headwater Elevr 576.72 ft Discharge 94.90 cfs Inlet Control HW Elev. 576.63 ft Tailwater Elevation 574.77 ft Outlet Control HW Elev. 576.72 ft Control Type Outlet Control Headwater Depth/Height 1.41 Grades Upstream Invert 572.50 ft Downstream Invert 572.00 ft Length 36.00 ft Constructed Slope 0.013889 ft/ft Hydraulic Profile Profile M2 Depth,Downstream 2.77 ft Slope Type Mild Normal Depth N/A ft Flow Regime Subcritical Critical Depth 2.24 ft Velocity Downstream 6.95 f/s Critical Slope 0.020883 ft/ft Section Section Shape Circular Mannings Coefficient 0.024 Section Material CMP Span 3.00 ft Section Size 36 inch Rise 3.00 ft Number Sections 2 Outlet Control Properties Outlet Control HW Elev. 576.72 ft Upstream Velocity Head 0.73 ft Ke 0.90 Entrance Loss 0.66 ft Inlet Control Properties Inlet Control HW Elev. 576.63 ft Flow Control Transition Inlet Type Projecting Area Full 14.1 ftz K 0.03400 HDS 5 Chart 2 M 1.50000 HOS 5 Scale 3 C 0.05530 Equation Form 1 Y 0.54000 Project Engineer:JOHN LEWIS s:\...\cv327b.cvm PAINTER-LEWIS,PLC CulvertMaster v3.0[3.0004] 03/07/14 11:32:53 AM ©Haestad Methods,Inc. 37 Brookside Road Waterbury,CT 06708 USA +1-203-755-1666 Page 2 of 2 ALBEMARLE COUNTY CV327B SWM/BMP EXHIBIT 6 OUTLET CONTROL DESIGN AND RIP RAP NOMOGRAPH page 11 ' +w CULVERT STONE APRON 2+- -1 1 FLOW SLOPE=0.00% 1119 III aenali erne I-I--.111=111_ STONE d50(MSD)=6" FILTER FABRIC CULVERT OUTLET PROTECTION DETAIL NOT TO SCALE CULVERT ID. L W D STONE d50(MSD) 1 10' 12' 12" 0.5' 2 10' 12" 12" 0.5' 3 20' 26' 16" 0.67' PROJECT SURVEY: CULVERT OUTLET PROTECTION NA NA SITE NUMBER CV327B SCALE: DATE: ALBEMARLE COUNTY, VIRGINIA SHOWN 3/5/14 SHEET: COP 411`• ' ,Pr 1992 3.18 laai 'azs de.Adpi OS p cr rev C•J .... CI CD 1-------.• „._%.. ,-. - -. A- -,•-.-z-e.--5--sEE: E:- .., -..-- 4-'-.._-'-:21.4 .... = A * ;i:-4}.:blij.• 71101 i•:7-f-h-IMP:*.. ---=- tt=,.....77,-:'4414; . -967-7-4- , ;':14ii.-. 1%. ,..•• *• -ej-17iimingk..,. ,-- ..,7,.-- .....__=---.-.--*.e., .,.*.....zr-„... .-;:- - • Atk, .‘tli!hikf.**- -. °:_ELINKrim%tit ,614,--14N.1.-;- ;:. • : N..."746,4, ,#e -Birgliffignitili6:7514DAMIIII c, .-L.._-- illiN.:" z.. .c'e 7772.1.NO11%.? ---- =:--7 -- "--7414,-,..*,O:--. MR . 0 ___:ILVIL -__ „... - ::Nrillk1171.r 1111ffab:.*il CV —0 , • CO I, . . o 0 MWRIBM=t`-- ... .--_::-.....-- \ , -<-2'''...- Z. 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C.) li 0 g IX 13 Source: USDA-SCS Plate 3.18-3 III - 164 vow ALBEMARLE COUNTY CV327B SWM/BMP EXHIBIT 7 PERFORMANCE-BASED WATER QUALITY COMPUTATIONS PERFORMANCE-BASED WATER QUALITY COUNTY/CITY:Albemarle County COMPUTATIONS DESCRIPTION:CV327B Worksheet 1- STEP 1- Determine the applicable area(A)and the post-developed impervious cover(I ) Applicable area(A)= 43.09 acres (Total property area) Post-development impervious cover: Structures= 0.00 acres Parking Lot= 0.00 acres Roadways= 0.48 acres other: Walkways= 0.00 acres Total Impervious Cover= 0.48 acres Imst=(total post-developmet impervious cover/A)x 100= olq STEP 2-Determine the average land cover condition(Iwatershed)or the existing impervious cover(Iexisting) Average land cover condition(Iwatershed): If the locality has determined land cover conditions for individual watersheds within its jurisdiction use the watershed specific value determined by the locality as Iwatsshed. Otherwise,use the Chesapeake Bay default value: 'watershed= 16 % f.xistina impervious cover(Iexisting): Determine the existing impervious cover of the development site if present. STEP 3-Determine the appropriate development situation The site information determined in Step 1 and Step 2 provide enough information to determine the appropriate development situation under which the performance criteria will apply. X Situation 1: I, .< 'watershed 1.1 < 16 Situation 2: "post > Iwatershed 1.1 > 16 Situation 3: Imo; > 'watershed 0.0 > 16 Situation 4: is served by an existing BMP. If the proposed development meets the criteria for the development Situation 1,than the low density development is considered to be the BMP and no pollutant removal is required. The calculation procedure for Situation 1 stops here. page 12