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HomeMy WebLinkAboutWPO201500057 Calculations 2016-07-11 AVINITY II STORMWATER MANAGEMENT CALCULATIONS PACKET Date of Calculations June 25, 2015 Revised: December 7, 2015 Revised: July 11, 2016 PREPARED BY: COLLINS ENGINEERING 200 GARRETT STREET, SUITE K CHARLOTTESVILLE, VA 22902 434.293.3719 PH 434.293.2813 FX www.collins-engineering.com DEQ Virginia Runoff Reduction Method Water Quality Calculations Virginia Runoff Reduction Method New Development Worksheet -v2.8 -June 2014 To be used w/2011 BMP Standards and Specifications Site Data Project Name:Avinity II SWM Date: 7/11/16 data input cells 1111111111111111M111.11011111111011calculation cells constant values 1. Post-Development Project& Land Cover Information Constants Annual Rainfall(inches) 43 _ Target Rainfall Event(inches) 1.00 _ Phosphorus EMC(mg/L) 0 26 Nitrogen EMC(mg/L) 1.86 Target Phosphorus Target Load(Ib/acre/yr) 0.41 J__ 0.90 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 0.00 0.00 0.00 0.00 Managed Turf(acres)-disturbed,graded for yards or other turf to be mowed/managed 0.00 4 43 0.00 0 00 4.43 Impervious Cover(acres) 0.00 5.36 0.00 0 00 5.36 Total 9.79 Rv Coefficients A soils B Soils C Soils D Soils Forest/Open Space 0.02 0.03 0.04 0.05 _ Managed Turf 0.15 0.20 0.22 0 25 Impervious Cover 0.95 0.95 0.95 0.95 Land Cover Summary Forest/Open Space Cover(acres) 0.00 Weighted Rv(forest) 0.00 Forest 0% Managed Turf Cover(acres) 4.43 Weighted Rv(turf) 0.20 %Managed Turf 45% Impervious Cover(acres) 5.36 Rv(impervious) 0.95 %Impervious 55% Total Site Area(acres) 9.79 Site Rv 0.61 Post-Development Treatment Volume(acre-ft 0.50 Post-Development Treatment Volume(cubic feet) 21,700 Post Development Load(TP)(Ib/yr) 13.63 Post_Development Load(TN)(Ib/yri 97.54 Total Load(TP)Reduction Required(Ib/yr) 9.62 Site Results 1 ! 1 D.A.A D.A.B D.A.C D.A. D D.A.E AREA CHECK IMPERVIOUS COVER 2 95 2 41 0 00 0 00 - 0 00 OK. IMPERVIOUS COVER TREATED 2 95 2 41 0 00 0 00 0 00 OK. TURF AREA 1 99 2 44 0 00 0 00 0 00 OK. TURF AREA TREATED 1 99 2 44 0.00 0 00 0 00 OK. AREA CHECK OK ov C)I( nk Phosphorus I 1 TOTAL TREATMENT VOLUME(cf)_ 21,700 + TOTAL PHOSPHORUS LOAD REDUCTION REQUIRED(LB/YEAR 9.62 RUNOFF REDUCTION(cf) 13060 PHOSPHORUS LOAD REDUCTION ACHIEVED(LB/YR 9.91 ADJUSTED POST-DEVELOPMENT PHOSPHORUS LOAD(TP)(Ib/yr 3.73 REMAINING PHOSPHORUS LOAD REDUCTION(LB/YR)NEEDEC CONGRATULATIONS!!YOU EXCEEDED THE TARGET REDUCTION BY 0 3 LB/YEAR! Nitrogen(for information purposes) _ TOTAL TREATMENT VOLUME(cf) RUNOFF REDUCTION(cf) NITROGEN LOAD REDUCTION ACHIEVED(LB/YR) ADJUSTED POST-DEVELOPMENT NITROGEN LOAD(TN)(Ib/yr). Virginia Runoff Reduction Method Worksheet Virginia Runoff Reduction Method New Development Worksheet-v2 8-June 2014 Site Data Summary Total Rainfall= 43 inches Site Land Cover Summary A Soils B Soils C Soils D Soils Total %of Total Forest(acres) 0 00 0 00 0 00 0 00 0 00 0 00 Turf(acres) 0 00 4 43 0 00 0 00 4 43 45 25 Impervious(acres) 0 00 5 36 0 00 0 00 5 36 54 75 9 79 100 00 Site Rv 0 61 Post Development Treatment Volume(ft3) 21700 Post Development TP Load(Ib/yr) 13 63 Post Development TN Load(lb/yr) _ 97 54 Total TP Load Reduction Required(lb/yr) 9 62 Total Runoff Volume Reduction(ft') 13060 Total TP Load Reduction Achieved(Ib/yr) 10 Total TN Load Reduction Achieved(Ib/yr) - 97 43 Adjusted Post Development TP Load(Ib/yr) 3.73 Remaining Phosphorous Load Reduction(Lb/yr)Required 0 00 Drainage Area Summary D.A.A D.A.B D.A.C D.A.D D.A.E Total Forest(acres) 0.00: 0.00 0.00 0.00 0.00 0 00 Turf(acres) 1 99 2.44 0.00 0.00' 0.00 4 43 Impervious(acres) 2 95 2 41' 0 00 0.00r 0.00_ 5 36 9 79 Drainage Area Compliance Summary D.A.A D.A.B D.A.C D.A.D D.A.E Total TP Load Red.(Ib/yr) 4 21' 5.70 0.00 0.00 0.00 9.91 TN Load Red.(lb/yr) 52 16 45 27 0 00 0 00. 0.00 97.43 Summary Print Virginia Runoff Reduction Method Worksheet Drainage Area A Summary Land Cover Summary A Soils B Soils C Soils D Soils Total %of Total Forest(acres) 0.00 0.00 0.00 0.00 0.00 0 00 Turf(acres) 0.00 1.99 0.00 0.00 1.99 40.28 Impervious(acres) 0.00 2.95 0.00 0.00 2.95 59.72 4.94 BMP Selections Practice Credit Area(acres) Downstream Practice 5.b.Dry Swale#2(Spec#10) Impervious: 0.18 6.a. Bioretention #1 Turf(Pervious): 0.4 6.a. Bioretention #1 6.a.Bioretention#1 or Urban Bioretention(Spec#9) Impervious: 2.77 Turf(Pervious): 1.59 Total Impervious Cover Treated(acres) 2 95 Total Turf Area Treated(acres) 1 99 Total TP Load Reduction Achieved in D.A.A(Ib/yr) 4.21 Total TN Load Reduction Achieved in D.A.A(Ib/yr) 52.16 Summary Print Virginia Runoff Reduction Method Worksheet Drainage Area B Summary Land Cover Summary A Soils B Soils C Soils D Soils Total %of Total Forest(acres) 0.00 0.00 0.00 0.00 0 00 0 00 Turf(acres) 0.00 2.44 0 00 0 00 2 44 50 31 Impervious(acres) 0 00 2 41 0 00 0 00 2 41 49.69 4 85 BMP Selections Practice Credit Area(acres) Downstream Practice 5.b.Dry Swale#2(Spec#10) Impervious: 0.03 6.b. Bioretention #2 Turf(Pervious): 0.08 6.b. Bioretention #2 6.b.Bioretention#2(Spec#9) Impervious: _ 2.38 None Turf(Pervious): 2.36 None Total Impervious Cover Treated(acres) 2 41 Total Turf Area Treated(acres) 2 44 Total TP Load Reduction Achieved in D.A.A(Ib/yr) 5 70 Total TN Load Reduction Achieved in D.A.A(Ib/yr) 45.27 Summary Print Virginia Runoff Reduction Method Worksheet Channel and Flood Protection Weighted CN 1-year 2-year storm 10-year storm Adjusted CN storm Adjusted Adjusted CN CN Target Rainfall Event(in) 0.00 0 00 0 00 D.A A CN 83 #N/A #N/A #N/A D A B CN 79 #N/A #N/A #N/A D A C CN 0 100 100 100 D A D CN 0 100 100 100 D A E CN 0 100 100 100 Summary Print Soils Mapping (Source: NRCS Web Soil Survey Online Database) Soil Map Albemarle County,Virginia (Amity II Soil Survey) R 719550 719600 719650 719700 719750 719800 y 37°59'40'N ' < • - _ , ;,y' ,,} x ,, . is, • 4 \ I i e4 ' • i 'ill .....1.. if 'f44, s': ' 41i, I AO F. r •••*. /i4} ",. .. 4 ' 72D r w pM a', i ,. .J.„ . 1 • ..t.• r s ..,,,If;....: .%1_: .11:. , , , it p*' 172C3- � ; - v- , .„ .0 .. i vC.3 - ,'' 4 106 IP .1, .., ',:: '41',., it / ;t 4/ w ... � r41,0 `F 3 r 'T 1. ' ' ,*.',.. 0 : t• et' :... , 41 ,,f,,,..„ , L} 1 j/ , „ !'�' c{#" 6 n lam"` �4I ,�' 44, 1 / it; tit Z` .,� i `� 'O ' ' 7r2D3 r 04 !% ,1 ,* '111. *, '''''Y.4, . „it ir ti^ t 1i 7 4*4 Or ,.• .1. ,• f f' I a 37°59'25'N •. r'. _._ - 37°59 25'N 71950 719550 719600 719650 719700 719750 719600 3 3 R Map Scale:1.2,160 iFprinted on A portrait(8.5"x 11")sheet Melmrs N 0 30 60 120 180 k Feet 0 100 200 400 600 AP P%legion:Web Me�r Corner o�ordir :WGS84 Edge tics:UTM Zone 17N WGS84 USDA Natural Resources Web Soil Survey 1/30/2015 Conservation Service National Cooperative Soil Survey Page 1 of 3 Soil Map—Albemarle County,Virginia (Avinity II Soil Survey) MAP LEGEND MAP INFORMATION Area of Interest(AOl) g Spoil Area The soil surveys that comprise your AOI were mapped at 1:15,800 Area of Interest(AOI) Stony Spot Warning:Soil Map may not be valid at this scale. Soils Very Stony Spot Soil Map Unit Polygons Enlargement of maps beyond the scale of mapping can cause ti Wet Spot misunderstanding of the detail of mapping and accuracy of soil line Soil Map Unit Lines placement.The maps do not show the small areas of contrasting Other soils that could have been shown at a more detailed scale. ® Soil Map Unit Points •r• Special Line Features Special Point Features Please rely on the bar scale on each map sheet for map to) Blowout Water Features measurements. Streams and Canals k;,t Borrow Pit Source of Map: Natural Resources Conservation Service Transportation Web Soil Survey URL: http://websoilsurvey.nrcs.usda.gov X Clay Spot Rails Coordinate System: Web Mercator(EPSG 3857) Closed Depression Interstate Highways Maps from the Web Soil Survey are based on the Web Mercator X Gravel Pit US Routes projection,which preserves direction and shape but distorts distance and area.A projection that preserves area,such as the Gravelly Spot Major Roads Albers equal-area conic projection,should be used if more accurate 0 Landfill Local Roads calculations of distance or area are required. A. Lava Flow Back round This product is generated from the USDA-NRCS certified data as of 9 the version date(s)listed below. 413 Marsh or swamp . Aerial Photography Soil Survey Area: Albemarle County,Virginia it% Mine or Quarry Survey Area Data: Version 10, Dec 11,2013 Miscellaneous Water Soil map units are labeled(as space allows)for map scales 1 50,000 0 Perennial Water or larger. $g Rock Outcrop Date(s)aerial images were photographed: May 10,2010—Jul 4, 2010 + Saline Spot The orthophoto or other base map on which the soil lines were •'••> Sandy Spot compiled and digitized probably differs from the background Severely Eroded Spot imagery displayed on these maps.As a result,some minor shifting of map unit boundaries may be evident. 40. Sinkhole 15 Slide or Slip oa Sodic Spot USDA Natural Resources Web Soil Survey 1/30/2015 '11 Conservation Service National Cooperative Soil Survey Page 2 of 3 Soil Map—Albemarle County,Virginia Amity II Soil Survey Map Unit Legend Albemarle County,Virginia(VA003) Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 71 B Rabun clay loam,2 to 7 percent 4.0 34.5% slopes 72C3 Rabun clay,7 to 15 percent 6.7 58.1% slopes,severely eroded 72D3 Rabun clay, 15 to 25 percent 0.8 7.3% slopes,severely eroded Totals for Area of Interest 106 100.0% USDA Natural Resources Web Soil Survey 1/30/2015 Conservation Service National Cooperative Soil Survey Page 3 of 3 SCS TR-55 Calculations U.S Department of Agriculture FL-ENG-21A Natural Resources Conservation Service 06/04 TR 55 Worksheet 2•Runoff Curve Number and Runoff Project• Proposed Avinity II Designed By KKW,PE Date 7/11/2016 Location. Located off Avon Street Extended,South of Amity I Checked By. KKW,PE Date: 7/11/2016 Check One Present X Developed 1.Runoff curve Number(CN) Cover description Soil name and CN(weighted)= Drainage Area (Cover type,treatment,and hydrologic condition; Area Product of CN Calculated Description hydrologic group percent impervious,unconnected connected CN total product/ p (Appendix A) p / (Acres) x Area total area S'Value impervious area ratio) Impervious Areas* 98 0 23 22.5 DA'A' B Woods in Good Condition 55 0 55 30 3 62 6 13 (Present) Lawns in Good Condition 61 4 40 268 4 DA'B' Impervious Areas 98 0 00 0 0 B Woods in Good Condition 55 0 00 0.0 61 6 39 (Present) Lawns in Good Condition 61 3 48 212 3 DA'C' Impervious Areas 98 0 00 0.0 B Woods in Good Condition 55 0 00 0.0 61 6.39 (Present) Lawns in Good Condition 61 1 13 68.9 DA'A' Impervious Areas 98 2 95 289 1 B Woods in Good Condition 55 0 00 0.0 83 2.03 (Developed) Lawns in Good Condition 61 1 99 121 4 DA'B' Impervious Areas 98 2.41 236.2 (Developed) B Woods in Good Condition 55 0 00 0 0 79 2 60 Lawns in Good Condition 61 2 44 148 8 *The impervious areas for DA'A'(pre-development)conservatively assume the demolition of the residence for the pond construction has already occurred 2.Runoff 1-Year Storm 2-Year Storm 10-Year Storm_Drainage Area Description Frequency-years 1 2 10 n/a Rainfall,P(24 hour)-inches 3.5 3.7 5.6 n/a Runoff,Q-inches 0.62 0 71 1 82 DA'A'(Present) Runoff,Q-inches 0 57 0 67 1 74 DA'B'(Present) Runoff,Q-inches 0.57 0 67 1 74 DA'C' (Present) Runoff,Q-inches 1 87 2 04 3 73 DA'A'(Developed) Runoff,Q-inches 1.59 1.75 3.36 DA'B'(Developed) U S Department of Agriculture FL-ENG-21A Natural Resources Conservation Service 06/04 TR 55 Worksheet 3 Time of Concentration(T,)or Travel Time(T,) Project Proposed Avinity II Designed By KKW,PE Date 6/25/2015 Location Located off Avon Street Extended,South of Avinity I Checked By KKW,PE Date 6/25/2015 Check One Present X Developed X Check One T, X T, Through subarea n/a DA'A' DA'B' DA'C' DA'A' DA'B' Segment ID (Present) (Present) (Present) (Developed) (Developed) Sheet Flow(Applicable to T,only) 1 Surface description(Table 3-1) Dense Grass Dense Grass Dense Grass Dense Grass Dense Grass 2 Manning's roughness coeff,n(Table 3-1 0 24 0 24 0 24 0 24 0 24 3 Flow length,L(total L<100)(ft) 100 100 100 62 100 4 Two-year 24-hour rainfall,P2(in) 3 7 3 7 3 7 3 7 3 7 5 Land slope,s(ft/ft) 0.03 0 07 0 06 0 03 0 05 6 Compute T,_[0 007(n•L)so)/P2 3 s°A 0 19 013 0 14 0 12 0 15 Shallow Concentrated Flow 7 Surface description(paved or unpaved) Unpaved Unpaved Unpaved Unpaved Unpaved 8 Flow Length,L(ft) 575 500 210 0 225 9 Watercourse slope,s(ft/ft) 0 08 0 13 0 09 0 00 0 04 10 Average velocity,V(Figure 3-1)(ft/s) 4 6 5 8 4 9 0 3 2 11 7,=L/3600•V 0.03 002 001 000 002 Channel Flow 12 Cross sectional flow area,a(ft2) c A c 3 n o N 3 m 3 13 Wetted perimeter,P„(ft) ',4.'a ° E 14 Hydraulic radius,r=a/Pw(ft) c 09, c :§ ,4 15 Channel Slope,s(ft/ft) .o ; .0ri.o °a °.° 16 Manning's Roughness Coeff,n `o ' I' d 17 V=[149r2ts°'s]/n $ 8n > 18 Flow length,L(ft) O1 %+ xi a 19 T,=L/3600N I I I I 0 03 I 0 03 20 Watershed or subarea T,or T, (Add T,in steps 6,11 and 19) 0.22 0.15 0.15 0.15 0.21 U S.Department of Agriculture FL-ENG-21C Natural Resources Conservation Service 06/04 TR 55 Worksheet 4 Graphical Peak Discharge Method Project. Proposed Avinity II Designed By. KKW,PE Date. 7/11/2016 Location* Located off Avon Street Extended,South of Avinity I Checked By KKW,PE Date* 7/11/2016 Check One Present X Developed X Drainage Area Drainage Area Drainage Area Drainage Area Drainage Area Drainage Area 1 Data Description Description Drainage Area Description Description Description Description Description DA'A' DA'B' DA'C' DA'A' DA'B' (Present) (Present) (Present) (Developed) (Developed) _ Drainage Area(Am)in miles'= 0 0081 0 0054 0 0018 0 0077 0.0076 Runoff curve number CN= 62 0 610 61 0 83 1 79.4 Time of concentration(Tc)= 0.22 0.15 0.15 0.15 0.21 Rainfall distribution type= II II II II II Pond and swamp areas spread throughout the watershed= 0 0 0 0 2.Frequency-years 1 2 10 1 2 10 1 2 10 1 2 10 1 2 10 3.Rainfall,P(24 hour)-inches 35 37 56 35 37 56 35 37 56 35 37 56 , 35 37 5.6 4.Initial Abstraction,la-inches 1 226 1 226 1 226 1 279 1 279 1 279 1 279 1 279 1 279 0.407 0.407 0 407 0.519 0.519 0.519 5 Compute la/P 0.35 0.33 0.22 0.37 0.35 0.23 0.37 0.35 0.23 0.12 0.11 0 07 0 15 0 14 0 09 6 Unit peak discharge,Qu-csm/in 610 650 725 710 750 850 710 750 850 900 900 1000 750 760 800 7 Runoff,Q from Worksheet 2-inches 0.62 0.71 1.82 0.57 0.67 1.74 0.57 0.67 1.74 1.87 2.04 3 73 _ 1 59 1 75 3 36 8 Pond and Swamp adjustment factor,Fp 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 9 Peak Discharge,Qp-cfs Routed through SWM Routed through SWM where Qp=Qu Am Q Fp 3 04 374 1069 2 21 271 8 06 072 088 262 Facility Facility Note Qu of 1000 csm/inch is the most conservative SCS TR-55 Qu Watershed Summary Pre-Development Post-Development DA 'A' 5.18 ac. 4.94 ac. DA 'B' 3.48 ac. 4.85 ac. DA'C' 1.13 ac. - Total= 9.79 ac. 9.79 ac. Outflow Summary: (1-Year Storm Event) Pre-Development Post-Development DA 'A' 3.04 cfs 1.25 cfs DA'B' 2.21 cfs 1.11 cfs DA'C' 0.72 cfs - Total= 5.97 cfs 2.36 cfs Outflow Summary: (2-Year Storm Event) Pre-Development Post-Development DA 'A' 3.74 cfs 2.62 cfs DA 'B' 2.71 cfs 1.52 cfs DA'C' 0.88 cfs - • Total= 7.34 cfs 4.14 cfs Outflow Summary: (10-Year Storm Event) Pre-Development Post-Development DA 'A' 10.69 cfs 14.89 cfs DA 'B' 8.06 cfs 6.35 cfs 2.62 cfs - DA'C' Total= 21.36 cfs 21.24 cfs Bioretention & Swale Sizing Calculations BIORETENTION BASIN'A'(LEVEL I)DESIGN&REQUIREMENTS: Treatment Volume(Per VRRM Calculations) 11,070 cf Minimum Treatment Volume Required 11,070 cf Minimum Surface Area Required(Tv/Storage Depth) 3,811 sf <-6'Mix at 25%porosity;3"pea gravel at 2%porosity, Surface Area Provided 1,820 sf 12"stone at 40%porosity&12"of ponding at 100% porosity STORMWATER MANAGEMENT FACILITY GRADING Area of Filter Elevation Cell Contours Volume (ft) (sf) (cf) 494.25 1,820 0 495.25 2,631 2,213 497.25 4,611 9,363 *A minimum surface area of 3,811 sf is required for this drainage area. A total of 1,820 sf filter floor surface area has been provided. Water quality credits shall be purchased for the remaining 1,991 sf surface area shortage,equivalent to 1.68 lbs/year of phosphorus. BIORETENTION BASIN'B'(LEVEL II)DESIGN&REQUIREMENTS: Treatment Volume(Per VRRM Calculations) 10,040 cf Minimum Treatment Volume Requirec 12,550 cf Minimum Forebay Volume Required(15%of Tv) 1,883 cf Forebay Volume Provided 1,935 cf Minimum Surface Area Required(Tv/Storage Depth 4,320 sf <-6'Mix at 25%porosity;3"pea gravel at 2%porosity, Surface Area Provided 4,320 sf 12"stone at 40%porosity&12"of ponding at 100% porosity STORMWATER MANAGEMENT FACILITY GRADING Area of Area of Filter Elevation Forebay Cell Volume Elevation Cell Contours Volume (ft) Contours(sf) (cf) (ft) (sf) (cf) 496 222 0 496 4,320 0 497 484 345 497 4,823 4,569 498 793 977 498 5,325 9,641 499 1,133 1,935 499 5,827 15,215 Area of Elevation Detention Cell Volume (ft) Contours(sf) (cf) 486 488 0 488 894 1,362 490 1,418 3,654 492 2,062 7,114 494 2,828 11,983 495 3,258 15,024 496 3,719 18,510 497 4,139 22,437 498 4,710 26,858 499 5,314 31,867 DRY TREATMENT#1 SWALE DESIGN&REQUIREMENTS: Treatment Volume(Per VRRM Calculations) 175 cf Minimum Treatment Volume Required 193 cf Minimum Surface Area Required(Tv/Storage Depth) 89 sf <-3'Mix at 25%porosity;3"pea gravel at 2%porosity, Surface Area Provided 188 sf 12"stone at 40%porosity&12"of ponding at 100% Minimum'Approximate'Surface Area 3%-10%of CDA porosity Surface Area Provided Relative to CDA 4 3% NOTE.Gutters shall outfall onto a concrete downspout splash block,where it shall flow to the dry swale via the rear yard's grassy lawn upland of the facility STORMWATER MANAGEMENT FACILITY GRADING Dry Swale Elevation Contours Volume (ft) (sf) (cf) 560 188 0 561 471 319 562 810 952 Notes. 1 Dry swale is approximately between 3%and 10%of the CDA. 2 Side slopes shall not exceed 3H:1V. 3 Where swale widths exceed 8',berms,check dams,level spreaders or multi-level cross sections are provided. 4 The maximum longitudial slope of Level 1 Dry Swales is 2%,and it's 1%for Level 2 designs.Slopes may be increased to 4%if check dams are provided DRY TREATMENT SWALE#2 DESIGN&REQUIREMENTS: Treatment Volume(Per VRRM Calculations) 910 cf Minimum Treatment Volume Required 1,001 cf Minimum Surface Area Required(Tv/Storage Depth) 465 cf <-3'Mix at 25%porosity;3"pea gravel at 2%porosity, Surface Area Provided 746 cf 12"stone at 40%porosity&12"of ponding at 100% Minimum'Approximate'Surface Area 3%-10%of CDA porosity Surface Area Provided Relative to CDA 3 0% NOTE•Gutters shall outfall onto a concrete downspout splash block,where runoff shall then flow into the grass channel pretreatment upland of to the dry swale STORMWATER MANAGEMENT FACILITY GRADING Dry Swale Elevation Contours Volume (ft) (sf) (cf) 520 746 0 521 1,172 951 522 1,662 2,361 Notes: 1 Dry swale is approximately between 3%and 10%of the CDA 2 Side slopes shall not exceed 3H•1V 3 Where swale widths exceed 8',berms,check dams,level spreaders or multi-level cross sections are provided. 4 The maximum longitudial slope of Level 1 Dry Swales is 2%,and it's 1%for Level 2 designs.Slopes may be increased to 4%if check dams are provided. DYO D S TM 1�� Access AI ��TC'AVr Riser B.r els Design Your Own Detention System ��E `` ii �� — Header ,qr CMP DETENTION SYSTEMS ,�/ ��- i` ---''"/,-v. - / //7i , /i/ A. l%UTCAU6 For design assistance, drawings, r�/!f �ir j/ o�4,401� E �� and pricing send completed worksheet to. ,-- --- // CONSTRUCTION PRODUCTS INC. dyods@contech-cpi.com ��// �. Band � �� � Project Summary ""„ ( Date. 6/8/2016 Project Name Avinity Estates City/County: Albemarle County Finished Grade State Virginia Pavement--\ Elevation Designed By' -- i Company: Collins Engineering Enter Information in Backfill to Grade N Telephone 434-293-3719 Blue Cells ¢ "^ Corrugated Metal Pipe Calculator Storage Volume Required (cf) 11,070 Limiting Width (ft). 30.000 ! Invert Depth Below Asphalt(ft) 14.00 Solid or Perforated Pipe: Solid Spacing Diameter__ Spacing Shape Or Diameter(in): 120 78 54 ft` Pipe Area LL, Number Of Headers. 0 Spacing between Barrels (ft). 3.00 Stone Width Around Perimeter of System (ft): 0 Depth A: Porous Stone Above Pipe(in) 0 Depth C Porous Stone Below Pipe(in). 0 _ Stone Porosity (0 to 40%)• 0 "-- . _ _�..._ System Sizing ' Pipe Storage. 11,153 cf System Layout Porous Stone Storage 0 cf Total Storage Provided: 11,153 cf 100.7% Of Required Storage Barrel 12 m Number of Barrels. 2 barrels Barrel 11 e Length per Barrel: 71.0 ft Barrel 10 0 Length Per Header. 0.0 ft Barrel 9 ,i Rectangular Footprint (W x L). 23 ft x 71 ft Barrel 8 ,i CONTECH Materials Barrel 7 ,t Total CMP Footage 142 ft Barrel 6 ,t Approximate Total Pieces: 8 pcs Barrel 5 ,t Approximate Coupling Bands. 6 bands Barrel 4 ,t Approximate Truckloads 4 trucks Barrel 3 it Construction Quantities** Barrel 2 - ' Total Excavation: 847 cy Barrel 1 ? 1 - Porous Stone Backfill For Storage: 0 cy stone Barrel Footage(w/o headers) Backfill to Grade Excluding Stone: 434 cy fill **Construction quantities are approximate and should be verified upon final design Post-Development Routing Calculations Subarea A Routing Calculations UGD BasinFlow printout INPUT: Basin: Subarea 'A' Routing - Detention Only 0 Contour Areas Elevation(ft) Area(sf) Computed Vol . (cy) 2 Storage Pipes Storage pipe 0 name: underground Detention diameter (in) 120.000 length (ft) 140.000 invert (ft) 498.290 angle 0.287 volume (cy) 407.243 Storage pipe 1 name: underground Detention diameter (in) 120.000 length (ft) 140.000 invert (ft) 498.290 angle 0.287 volume (cy) 407.243 Start_Elevation(ft) 498.29 Vol . (cy) 0.00 4 Outlet Structures Outlet structure 0 Orifice name: Low-Flow Orifice area (sf) 0.108 diameter or depth (in) 4.450 width for rect. (in) 0.000 coefficient 0.600 invert (ft) 498.290 multiple 1 discharge into riser Outlet structure 1 Orifice name: Mid-Flow Orifice area (sf) 0. 349 diameter or depth (in) 8.000 width for rect. (in) 0.000 coefficient 0.600 invert (ft) 504.290 multiple 6 discharge into riser Outlet structure 2 Culvert name: Barrel multiple 1 discharge out of riser D (in) 24.000 h (in) 0.000 Length (ft) 84.000 Slope 0.005 Manning's n 0.013 Inlet coeff. Ke 0. 500 Equation constant set 3 Page 1 Subarea A Routing Calculations UGD Invert (ft) 498.290 Outlet structure 3 orifice name: Emergency Spillway Simulation area (sf) 7.386 diameter or depth (in) 36.800 width for rect. (in) 0.000 coefficient 0.600 invert (ft) 506.790 multiple 1 discharge into riser 3 Inflow Hydrographs Hydrograph 0 SCS name: 1- Yr. Storm- SCS Method Area (acres) 4.940 CN 83.000 Type 2 rainfall , P (in) 3. 500 time of conc. (hrs) 0.1500 time increment (hrs) 0.0200 time limit (hrs) 30.000 fudge factor 1.00 routed true peak flow (cfs) 10.691 peak time (hrs) 11.930 volume (cy) 1233.423 Hydrograph 1 SCS name: 2- Yr. Storm- SCS Method Area (acres) 4.940 CN 83.000 Type 2 rainfall , P (in) 3.700 time of conc. (hrs) 0.1500 time increment (hrs) 0.0200 time limit (hrs) 30.000 fudge factor 1.00 routed true peak flow (cfs) 11.665 peak time (hrs) 11.930 volume (cy) 1345.848 Hydrograph 2 SCS name: 10- Yr. Storm- SCS Method Area (acres) 4.940 CN 83.000 Type 2 rainfall , P (in) 5.600 time of conc. (hrs) 0.1500 time increment (hrs) 0.0200 time limit (hrs) 30.000 fudge factor 1.00 routed true peak flow (cfs) 21.408 peak time (hrs) 11.930 volume (cy) 2469.903 OUTPUT: Page 2 Subarea A Routing Calculations UGD Routing Method: storage-indication Hydrograph 0 Routing Summary of Peaks: 1- Yr. Storm- SCS Method inflow (cfs) 10.681 at 11.94 (hrs) discharge (cfs) 1.250 at 12.32 (hrs) water level (ft) 504.254 at 12.34 (hrs) storage (cy) 470.608 Hydrograph 1 Routing Summary of Peaks: 2- Yr. storm- SCS Method inflow (cfs) 11.654 at 11.94 (hrs) discharge (cfs) 2.621 at 12.18 (hrs) water level (ft) 504.529 at 12.18 (hrs) storage (cy) 498.718 Hydrograph 2 Routing Summary of Peaks: 10- Yr. Storm- SCS Method inflow (cfs) 21.388 at 11.94 (hrs) discharge (cfs) 14.890 at 12.06 (hrs) water level (ft) 506.398 at 12.06 (hrs) storage (cy) 677.604 wed Jun 29 21:43:05 EDT 2016 Page 3 Subarea B Routing Calculations-Bioretention Cell BasinFlow printout INPUT: Basin: Subarea B Routing Calculations - Bioretention Cell 4 Contour Areas Elevation(ft) Area(sf) Computed vol . (cy) 496.00 4320.00 0.0 497.00 4823.00 169.2 498.00 5325.00 357.1 499.00 5827.00 563. 5 Start_Elevation(ft) 496.00 Vol . (cy) 0.00 1 outlet Structures outlet structure 0 Weir name: Bioretention Cell Spillway length (ft) 55.000 side angle 26.770 coefficient 3.000 invert (ft) 497.000 multiple 1 discharge through dam 5 Inflow Hydrographs Hydrograph 0 SCS name: 1-yr 24-hr Peak SCS TR-55 Storm Event Area (acres) 4.850 CN 79.000 Type 2 rainfall , P (in) 3. 500 time of conc. (hrs) 0.2100 time increment (hrs) 0.0200 time limit (hrs) 30.000 fudge factor 1.00 routed true peak flow (cfs) 8.142 peak time (hrs) 11.982 volume (cy) 1020.145 Hydrograph 1 SCS name: 2-yr 24-hr Peak SCS TR-55 Storm Event Area (acres) 4.850 CN 79.000 Type 2 rainfall , P (in) 3.700 time of conc. (hrs) 0.2100 time increment (hrs) 0.0200 time limit (hrs) 30.000 fudge factor 1.00 routed true peak flow (cfs) 8.957 peak time (hrs) 11.982 volume (cy) 1122. 347 Hydrograph 2 SCS name: 10-yr 24-hr Peak SCS TR-55 Storm Event Area (acres) 4.850 Page 1 Subarea B Routing Calculations-Bioretention Cell CN 79.000 Type 2 rainfall , P (in) 5.600 time of conc. (hrs) 0.2100 time increment (hrs) 0.0200 time limit (hrs) 30.000 fudge factor 1.00 routed true peak flow (cfs) 17.285 peak time (hrs) 11.982 volume (cy) 2165.824 Hydrograph 3 SCS name: 25-yr 24-hr Peak SCS TR-55 Storm Event Area (acres) 4.850 CN 79.000 Type 2 rainfall , P (in) 7.000 time of conc. (hrs) 0.2100 time increment (hrs) 0.0200 time limit (hrs) 30.000 fudge factor 1.00 routed true peak flow (cfs) 23.835 peak time (hrs) 11.982 volume (cy) 2986.459 Hydrograph 4 SCS name: 100-yr 24-hr Peak SCS TR-55 Storm Event Area (acres) 4.850 CN 79.000 Type 2 rainfall , P (in) 9.100 time of conc. (hrs) 0.2100 time increment (hrs) 0.0200 time limit (hrs) 30.000 fudge factor 1.00 routed true peak flow (cfs) 34.000 peak time (hrs) 11.982 volume (cy) 4260.150 OUTPUT: Routing Method: storage-indication Hydrograph 0 Routing Summary of Peaks: 1-yr 24-hr Peak SCS TR-55 Storm Event inflow (cfs) 8.136 at 11.98 (hrs) discharge (cfs) 7.688 at 12.00 (hrs) water level (ft) 497.129 at 12.00 (hrs) storage (cy) 192.497 Hydrograph 1 Routing Summary of Peaks: 2-yr 24-hr Peak SCS TR-55 Storm Event inflow (cfs) 8.951 at 11.98 (hrs) discharge (cfs) 8.631 at 12.00 (hrs) water level (ft) 497.140 at 12.00 (hrs) storage (cy) 194.374 Hydrograph 2 Page 2 Subarea B Routing Calculations-Bioretention Cell Routing Summary of Peaks: 10-yr 24-hr Peak SCS TR-55 Storm Event inflow (cfs) 17.273 at 11.98 (hrs) discharge (cfs) 16.819 at 11.98 (hrs) water level (ft) 497.218 at 11.98 (hrs) storage (cy) 208. 599 Hydrograph 3 Routing Summary of Peaks: 25-yr 24-hr Peak SCS TR-55 Storm Event inflow (cfs) 23.817 at 11.98 (hrs) discharge (cfs) 23.449 at 11.98 (hrs) water level (ft) 497.272 at 11.98 (hrs) storage (cy) 218.485 Hydrograph 4 Routing Summary of Peaks: 100-yr 24-hr Peak SCS TR-55 Storm Event inflow (cfs) 33.975 at 11.98 (hrs) discharge (cfs) 33.663 at 11.98 (hrs) water level (ft) 497.346 at 11.98 (hrs) storage (cy) 232.123 Fri Oct 16 14: 51: 53 EDT 2015 Page 3 Subarea B Routing Calculations-Detention Cell BasinFlow printout INPUT: Basin: Subarea B Routing Calculations 10 Contour Areas Elevation(ft) Area(sf) Computed vol . (cy) 486.00 488.00 0.0 488.00 894.00 50.4 490.00 1418.00 135.3 492.00 2062.00 263. 5 494.00 2828.00 443.8 495.00 3258.00 556.4 496.00 3719.00 685.6 497.00 4139.00 831.0 498.00 4710.00 994.8 499.00 5314.00 1180. 3 Start_Elevation(ft) 486.00 Vol . (cy) 0.00 5 Outlet Structures Outlet structure 0 Orifice name: Orifice area (sf) 0.110 diameter or depth (in) 4. 500 width for rect. (in) 0.000 coefficient 0. 500 invert (ft) 486.000 multiple 1 discharge into riser Outlet structure 1 Orifice name: Mid-flow Orifice area (sf) 0.196 diameter or depth (in) 6.000 width for rect. (in) 0.000 coefficient 0. 500 invert (ft) 492.670 multiple 4 discharge into riser Outlet structure 2 Weir name: Riser diameter (in) 30.000 side angle 0.000 coefficient 3. 300 invert (ft) 496.670 multiple 1 discharge into riser transition at (ft) 0.760 orifice coef. 0. 500 orifice area (sf) 4.909 Outlet structure 3 Culvert name: Barrel multiple 1 discharge out of riser D (in) 15.000 Page 1 Subarea B Routing Calculations-Detention Cell h (in) 0.000 Length (ft) 80.000 Slope 0.005 Manning's n 0.013 Inlet coeff. Ke 0. 500 Equation constant set 3 Invert (ft) 486.000 Outlet structure 4 weir name: Emergency Spillway length (ft) 45.000 side angle 63.430 coefficient 3.000 invert (ft) 497.750 multiple 1 discharge through dam 5 Inflow Hydrographs Hydrograph 0 Curve name: ROUTED OUTFLOW 1-yr 24-hr Peak SCS TR-55 Storm Event time incr (minIhrs) 0.02 time limit (minIhrs) 30.00 file: 1 YEAR-0.02 hr intervals.txt volume (cy) 500.93 routed true time in hours true Hydrograph 1 Curve name: ROUTED OUTFLOW 2-yr 24-hr Peak SCS TR-55 Storm Event time incr (minIhrs) 0.02 time limit (minIhrs) 30.00 file: 2 YEAR-0.02 hr intervals.txt volume (cy) 572.95 routed true time in hours true Hydrograph 2 Curve name: ROUTED OUTFLOW 10-yr 24-hr Peak SCS TR-55 Storm Event time incr (minIhrs) 0.02 time limit (minIhrs) 30.00 file: 10 YEAR-0.02 hr intervals.txt volume (cy) 1339.02 routed true time in hours true Hydrograph 3 Curve name: ROUTED OUTFLOW 25-yr 24-hr Peak SCS TR-55 Storm Event time incr (minIhrs) 0.02 time limit (minIhrs) 30.00 file: 25 YEAR-0.02 hr intervals.txt volume (cy) 1982.64 routed true time in hours true Hydrograph 4 SCS name: 100-yr 24-hr Peak SCS TR-55 Storm Event Area (acres) 4.850 Page 2