Loading...
HomeMy WebLinkAboutWPO201500057 Calculations 2015-06-25 AVINITY II STORMWATER MANAGEMENT CALCULATIONS PACKET Date of Calculations June 25, 2015 PREPARED BY: COLLINS cNGINEERING 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 I&II SWM Conceptual Design Date: 10/14/14 data input cells calculation cells constant values 1. Post-Development Project&Land Cover Information Constants Annual Rainfall(inches) I . Target Rainfall Event(inches) 1.00 Phosphorus EMC(mg/L) 0.26 Nitrogen EMC(mg/L)J 1.11-.86 Target Phosphorus Target Load(Ib/acre/yr) 0.41 Pj 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 _ - . e= . . 1.89 • • 0.00 0.00 Managed Turf(acres)--disturbed,graded for yards or other turf to be mowed/managed 0.00 4 22 0.00 0.00 4.22 Impervious Cover(acres) 0 00 5.57 0 00 __t ,, 0.00 5.57 Total - 9.79 Rv Coefficients A soils B Soils C Soils D Soils Forest/Open Space 0.02 0.03 0.04 -mr 0.05 .4Pli Managed Turf In 0.15 0.20 0.22 0.25 Impervious Cover 0.95 0.95 0.95 0.95 I Land Cover SummaryJ Forest/Open Space Cover(acres) 0.00 Weighted Rv(forest) 0.00 %Forest 0% Managed Turf Cover(acres) 4.22 Weighted Rv(turf) 0.20 %Managed Turf 43% Impervious Cover(acres) 5.57 Rv(impervious) 0.95 %Impervious 57% Total Site Area(acres) 9 79 Site Rv 0.63 Post-Development Treatment Volume(acre-ft) 0.51 _ Post-Development Treatment Volume(cubic feet) 22,272 Post_Development Load(TP)(Ib/yr) 13.99 Post_Development Load(TN)(Ib/yr . 1 Total Load(TP)Reduction Required(Ib/yr) 9.98 Site Results D.A.A D.A.B D.A.C D.A.D D.A.E 1 AREA CHECK IMPERVIOUS COVER 3 15 2.42 0 00 0 00 0.00 0;,, IMPERVIOUS COVER TREATED 3 15 2 42 0.00 0 00 0.00 OK TURF AREA 1 79 2 43 0 00 0 00 0 00 OK. TURF AREA TREATED 1 79 2 43 0 00 0 00 0 00 OK AREA CHECK Or. Phosphorus 1 TOTAL TREATMENT VOLUME(cf) 22,272 TOTAL PHOSPHORUS LOAD REDUCTION REQUIRED(LB/YEAR 9.98 RUNOFF REDUCTION(cf) 14914 PHOSPHORUS LOAD REDUCTION ACHIEVED(LB/YRj 10.60 ADJUSTED POST-DEVELOPMENT PHOSPHORUS LOAD(TP)(Ib/yri 3.40 REMAINING PHOSPHORUS LOAD REDUCTION(LB/YR)NEEDED CONORATULATIONOII YOU EXCEEDED THE TARGET REDUCTION BY CO LI)YEARI Nitrogen(for information purposes) TOTAL TREATMENT VOLUME(cf) 22,272 RUNOFF REDUCTION(cf) 14914 NITROGEN LOAD REDUCTION ACHIEVED(LB/YR) 99.99 ADJUSTED POST-DEVELOPMENT NITROGEN LOAD(TN)(Ib/yrin 0.11 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 22 0 00 0 00 4.22 43 11 Impervious(acres) 0 00 5 57 0.00 0.00 5 57 56 89 9 79 100.00 Site Rv 0 63 Post Development Treatment Volume(ft3) 22272 Post Development TP Load(Ib/yr) 13 99 Post Development TN Load(Ib/yr) 100 11 Total TP Load Reduction Required(Ib/yr) 9.98 Total Runoff Volume Reduction(ft') 14914 Total TP Load Reduction Achieved(Ib/yr) 11 Total TN Load Reduction Achieved(Ib/yr) 99.99 Adjusted Post Development TP Load(Ib/yr) 3.40 Remaining Phosphorous Load Reduction(Lb/yr)Required 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 79 2 43 0 00 0.00 0 00 4.22 Impervious(acres) 3.15 2.42 0 00 0 00 0 00 5 57 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) 4.57 6.03 0.00 0 00 0 00 10.60 TN Load Red.(Ib/yr) 54.60 45 39 0 00 0 00 0 00 99.99 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 79 0 00 0.00 1 79 36.23 Impervious(acres) 0 00 3 15 0 00 0.00 3 15 63.77 4 94 t / BMP Selections Practice Downstream ' actice 5.a.Dry Swale#1(Spec#10) L 10112=3•111111111 S.b.Dry Swale#2(Spec#10) Impervious: Wir"5.a.Dry Swale #1 Turf(Pervious): 0.65 5.a.Dry Swale #1 Total Impervious Cover Treated(acres) 3 15 Total Turf Area Treated(acres) 1.79 Total TP Load Reduction Achieved in D.A.A(Ib/yr) 4 57 Total TN Load Reduction Achieved in D.A.A(Ib/yr) 54.60 � d...- e i Itn r e-,,_ __,--,-----A-t... tb , .. . ,.... ,.. \ (2=1 . ,yres-, U `'14'9'sji,,,,,)„D .., o\. ' ,,_.,s-. Ji) r' 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 2.43 0.00 0.00 2 43 50 10 Impervious(acres) 0.00 2.42 0.00 0 00 2 42 49 90 4 85 BMP Selections Practice Credit Area(acres) Downstream Practice 5.b.Dry Swale#2(Spec#10) Impervious: 0.04 6.b. Bioretention #2 Turf(Pervious): 0.05 6.b. Bioretention #2 6.b.Bioretention#2(Spec#9) Impervious: 2.38 9.c.Sheetflow to Vegetated Filter Strip Turf(Pervious): 2)8 9.c.Sheetflow to Vegetated — FjlterStrip 9.c.Sheetflow to Vegetated Filter Strip in A Soils or Compost Impervious: 0 Amended B/C/D Soils(Spec#2&#4) Turf(Pervious): 0 Total Impervious Cover Treated(acres) 2 42 `J Total Turf Area Treated(acres) 2.43 Total TP Load Reduction Achieved in D.A.A(Ib/yr) 6 03 Total TN Load Reduction Achieved In D.A.A(Ib/yr) 45 39 Summary Print Soils Mapping (Source: NRCS Web Soil Survey Online Database) Soil Map—Albemarle County,Virginia R (Avinity II Soil Survey) k 719500 719550 719600 719650 719700 719750 719800 /._. 4 . . . •, . ... ., ,...f a 411, r,14! �, ? ,; �b_s : 4 �. . . AP ikr.4"-:Aip "..."., ., o ,:4F#* 41‘4, - '.' ;` i' * �3 j '� 41111, 72D3 • �' _X ‘ ,a,,,,:o 0, . , rp )#.,,i.„2. ,, . . .. . - , r# A . . • ,. ,. ., . i I ,: • ` ,,, 4, • , , , • 1... ? h • • ns+ rjp Y.. • I '7 ♦♦♦��� �,�{ .,. 'v '{ •/fox r1yY get' y • p.;144 • ` I 4° +",.. r ;, F- ,.� .,Atf rr7'GC3 4. • ��' y..t ,. ••••;F: '' ' .„.t* y ,, f - -..',. 40,4 flit 7.., - • i „ ' 1 +' „ 1t f�fa .4101 ,, f • • ..."t r:.:• • ilia....+ , - • -- ' IP . Ili„ • . , :7 t Y P - .'''-" : •:;,... '• . r, .,..... • 1 4r r r I.> 4404 t'' i • I 1 t .b y t /( r 'A lri ...A. .. t, 37°942SN - - .a,i i i. 37'97 25'N 719500 719550 719600 719650 719/00 719800 3 ry k Map Scale:1:2,160 if prinked on A portrait(8.5"x 11")sheet. Meters N o 30 60 120 180 Feet A 1Map pn edkn:00 Web Mer44x200 Corner coordinates:WGS84400 Edge q6:IJTM Zone 17N WGS84600 USDA Natural Resources Web Soil Survey 1/30/2015 Iii 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(A01) 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 • Wet Spot misunderstanding of the detail of mapping and accuracy of soil line • • Soil Map Unit Lines placement.The maps do not snow the small areas of contrasting Other soils that could have been shown at a more detailed scale. • Soil Map Unit Points 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 0 Borrow Pit Source of Map: Natural Resources Conservation Service Transportation Web Soil Survey URL: http.//websoilsurvey.nres.usda.gov ( 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 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. Lava Flow Background This product is generated from the USDA-NRCS certified data as of the version date(s)listed below. (. Marsh or swamp alba, Aerial Photography min Soil Survey Area: Albemarle County,Virginia Mine or Quarry Survey Area Data. Version 10,Dec 11,2013 (g. Miscellaneous Water Soil map units are labeled(as space allows)for map scales 1.50,000 0 Perennial Water or larger. 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. 0 Sinkhole Slide or Slip Sodic Spot USDA Natural Resources Web Soil Survey 1/30/2015 Conservation Service National Cooperative Soil Survey Page 2 of 3 Soil Map—Albemarle County,Virginia Avinity II Soil Survey Map Unit Legend Albemarle County,Virginia(VA003) Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 71B 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 11.6 100.0% 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 II \ L-ENG-2 .A 1A Natural Resources Conservation Service �t 06/04 TR 55 Worksheet 2 Runoff Curve Number and Runoff —� Project: Proposed Amity II Designe• By: KKW,•- Date: 6/25/2015 Location: Located off Avon Street Extended,South of Avinity I Che ed By: KKW,P Date 6/25/2015 Check One Present X Developed 1.Runoff curve Number(CN) Soil name and Cover description Drainage Area CN(weighted)= g (Cover type,treatment,and hydrologic co.drtion; Area • oduct of CN Calculated hydrologic group CN total product/ Description percent impervious;unconnected/co ected (Acres) x Area 'S'Value (Appendix A) impervious area ratio) total area DA'A' Impervious Areas* 98 0 23 22.5 (Present) B Woods inGood Condition 55 0 55 30 3 62 6 13 Lawns in Good Condition 6:. 4.40 -68.4 DA'B' Impervious Areas 98 0 00 11.0 (Present) B Woods in Good Condition 55 0 00 I 0 61 6 39 Lawns in Good Condition 61 3 48 2 2 3 DA'C' Impervious Areas 98 0 00 I 0 (Present) 8 Woods in Good Condition 55 0 00 I 0 61 6 39 Lawns in Good Condition 61 1 13 .8 9 DA'A' Impervious Areas 98 3 15 :08 7 (Developed) B Woods in Good Condition 55 0 00 0.0 85 1 82 Lawns in Good Condition 6- 1 79 109.2 DA'B' Impervious Areas 2 42 237.2 (Developed) B Woods in Good Condition 0 00 0 0 79 2.58 Lawns in Good Condition 2 43 148.2 *The impervious areas for DA'A'(pre-development)conservatively assume the demolition o he residence for/the••nd 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 98 2.16 3 88 DA'A'(Developed) Runoff,Q-inches 1.60 1 76 3.37 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(Tr) 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,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) 100 100 100 100 100 4 Two-year 24-hour rainfall,Pa(in) 3 7 3 7 3 7 3 7 3 7 5 Land slope,s(ft/ft) 0 03 0.07 0 06 0 09 0.05 6 Compute T,_[0007(n•L(x[/Pz's s" 019 013 014 012 OSS Shallow Concentrated Flow. 7 Surface description(paved or unpaved) Unpaved Unpaved Unpaved Unpaved Unpaved 8 Flow Length,L(ft) 575 500 210 225 225 9 Watercourse slope,s(ft/ft) 0 08 0 13 0.09 0 09 0 04 10 Average velocity,V(Figure 3-1)(ft/s) 4 6 S 8 4 9 4 9 3 2 11 TT=L/3600'V 003 0.02 001 0.01 002 Channel Flow 12 Cross sectional flow area,a(ft) 9 III. ` o m o 13 Wetted perimeter,P„(ft) E c v- E 14 Hydraulic radius,r=a/P„(ft) c as c ° 1, °15 Channel Slope,s(ft/ft) g1-4. `m 0 °�°, 16 Manning's Roughness Coeff,n i5 ;< ' u m `o `o 17V=[149rs°.s]/n 2 o` n u 18 Flow length,L(ft) '^44 °1 0 19 T,=L/3600*V 0 02 0 03 20 Watershed or subarea T,or T, (Add T,in steps 6,11 and 19) 0.22 0.15 0.15 021 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 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 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' DAB DA'C' DA'A' DAB (Present) (Present) (Present) (Developed) (Developed) Drainage Area(Am)in miles= 0.0081 0.0054 0.0018 0.0077 0.0076 Runoff curve number CN= 620 61.0 61.0 846 795 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 3.5 3.7 56 35 37 5.6 35 37 5.6 3.5 37 5.6 35 37 56 4 Initial Abstraction,la-inches +-"a t22A_ L 724..,1 279 1 279 1279 1 279 1 279 1279 0 364 0.364 0 364 0.517 0 517 0 517 5 Compute la/P C.... -0.35 0.33 0 22 0. 35 0 23 0.37 0.35 0 23 0 10 010 0.07 0 15 014 0.09 6 Unit peak discharge,Qu-csm/in 610 650 725 710 50 850 710 750 850 900 900 1000 750 760 S00 7 Runoff,Q from Worksheet 2-inch 0 62 0 71 182 0.5 0.67 1 74 0 57 0.67 1 74 1 98 2 16 3.88 1 60 176 3 37 8 Pond and Swamp adjustment fact 1 + 1 1 1 1 1 1 1 1 1 1 1 1 9 Peak Discharge,Op-cfs Routed through SWM Routed through SWM where Qp=Qu Am Q Fp 3 3 74 10 69 2 21 2 71 8.06 0 72 0.88 2 62 Facility Facility Note Qu of 1000 csm/inch is the most conserva ive 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' 113 ac - Total= 9 79 ac. 9 79 ac Outflow Summary:(1-Y ar Storm Ewing Pre-Development P t-Develops ent DA'A' 3 04 cfs 0 87 c s DA'B' 2 21 ds 141c)s DA'C' 072 cfs - Total= 5.97 cfs 2.28 as Outflow Summary(2-Ye r Storm E rent) Pre-Development P t-Develop ent DA'A' 374cfs 091 DA'B' 271cfs 249 DA'C' 088 cfs - Total= 7.34 cfs 3.40 cf Outflow Summary:(10-Year torm Ev nt) Pre-Development Post- velopmeInt DA'A' 10 69 ds 7 82 cfs DA'B' 806 cfs 08cfs DA'C' 2 62 cfs - Total= 21 36 cfs 18 9 cfs Swale Sizing Calculations "DRY TREATMENT SWALE"'A'DESIGN&REQUIREMENTS: Treatment Volume(Per VRRM Calculations) 10,597 cf Minimum Treatment Volume Required 10,597 cf Minimum Surface Area Required(Tv/Storage Depth) 4,917 sf <-3'Mix at 25%porosity,3"pea gravel at 2%porosity, Surface Area Provided 5,317 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 3% NOTE•Per DEQ Spec.#10,"A Dry Treatment Swale is located to accept runoff as concentrated flow or sheet flow from non-linear drainage areas at one or more locations and,due to site constraints or other issues,is configured as a linear practice(as opposed to a bioretention configuration) A dry treatment swale can also be used to convey stormwater from the contributing drainage area to a discharge point.." STORMWATER MANAGEMENT FACILITY GRADING Area of Filter Cell Elevation Contours Volume (ft) (sf) (cf) 490 5,317 0 492 7,332 12,595 494 8,596 28,506 496 10,640 47,706 � S .4) BIORETENTION BASIN'B'DESIGN&REQUIREMENTS: Treatment Volume(Per VRRM Calculations) 10,005cf Minimum Treatment Volume Required / 11,006 Minimum Forebay Volume Required(15%of Tv) ` cf Forebay Volume Provided 1,996 cf Minimum Surface Area Required(Tv/Storage Depth) 3,788 sf / <-6'Mix at 25%porosity;3"pea gravel at 2%porosity, Surface Area Provided 3,792 sf 12"stone at 40%porosity&12"of ponding at 100% porosity STORMWATER MANAGEMENT FACILITY GRADING Area of Ar of Filte?\ Total Facility Elevation Forebay Cell Volume Elevation ell Contours Volume Elevation Contours, Volume (ft) Contours(sf) (cf) (ft) (sf) (cf) (ft) Total(sf) (cf) 492 5 37 0 492.5 3,792 0 492 5 3,829 0 494 138 123 494 4,371 6,117 494 4,509 6,247 496 452 683 49 5,656 16,117 496 6,108 16,823 498 885 1,996 49� 6,984 28,733 498 7,869 30,763 \\._ , II/5 DRY TREATMENT#1 SWALE DESIGN&REQUIREMENTS: Treatment Volume(Per VRRM Calculations) 1SS cf Minimum Treatment Volume Required 207 cf Minimum Surface Area Required(Tv/Storage Depth) 96 cf <-3'Mix at 25%porosity;3"pea gravel at 2%porosity, Surface Area Provided 436 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 D0 0% 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) 558 ,. 0 559 SDa 651 560 1,409 1,793 DRY TREATMENT SWALE#2 DESIGN&REQUIREMENTS: Treatment Volume(Per VRRM Calculations) 1.020 cf Minimum Treatment Volume Required 1,122 cf Minimum Surface Area Required(Tv/Storage Depth) 521 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 _ % 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 1,1;2 951 522 1,662 2,361 DRY TREATMENT SWALE#3 DESIGN&REQUIREMENTS: Treatment Volume(Per VRRM Calculations) 1.590 cf Minimum Treatment Volume Required 1,749 cf Minimum Surface Area Required(Tv/Storage Depth) 812 cf <-3'Mix at 25%porosity;3"pea gravel at 2%porosity, Surface Area Provided 842 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 ;% 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) 530 84? 0 531 1,636 1,217 532 2,487 3,264 Post-Development Routing Calculations Subarea A Routing Calculations-NEw-lyear BasinFlow printout INPUT: Basin: Subarea A Routing Calculations 4 Contour Areas Elevation(ft) Area(sf) Computed Vol . (cy) 490.00 5317.00 0.0 492.00 7332.00- 466.5 494.00 8596.00 1055.8 496.00 10640.00 1766.9 Start_Elevation(ft) 490.00 Vol . (cy) 0.00 r� l 2- 4 Outlet Structures Outlet structure 0 Orifice c& - may/ name: Orifice 2 " 1 area (sf) 0.049 diameter or depth (in) 3.000 width for rect. (in) 0.000 coefficient 0.500 invert (ft) 491.000 multiple 3 discharge into riser Outlet structure 1 wei r name: Riser diameter (in) 15.000 side angle 0.000 coefficient 3.300 invert (ft) 493.650 multiple 1 discharge into riser transition at (ft) 0.380 orifice coef. 0.500 orifice area (sf) 1.227 Outlet structure 2 Culvert name: Barrel multiple 1 discharge out of riser D (in) 15.000 h (in) 0.000 Length (ft) 64.000 Slope 0.005 Manning's n 0.013 Inlet coeff. Ke 0.500 Equation constant set 3 Invert (ft) 490.000 Outlet structure 3 Weir name: Emergency Spillway length (ft) 55.000 side angle 0.000 coefficient 3.000 invert (ft) 494.650 multiple 1 discharge through dam Page 1 Subarea A Routing Calculations-NEW-lyear 4 Inflow Hydrographs Hydrograph 0 SCS name: 1-yr 24-hr Peak SCS TR-55 Storm Event Area (acres) 4.940 CN 85.000 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) 11.598 peak time (hrs) 11.930 volume (cy) 1338.149 Hydrograph 1 SCS name: 2-yr 24-hr Peak SCS TR-55 Storm Event Area (acres) 4.940 CN 85.000 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) 12.606 peak time (hrs) 11.930 volume (cy) 1454.407 Hydrograph 2 SCS name: 10-yr 24-hr Peak SCS TR-55 Storm Event Area (acres) 4.940 CN 85.000 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) 22.585 peak time (hrs) 11.930 volume (cy) 2605.797 Hydrograph 3 SCS name: 100-yr 24-hr Peak SCS TR-55 Storm Event Area (acres) 4.940 CN 85.000 Type 2 rainfall , P (in) 9.100 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) 41.867 Page 2 Subarea A Routing Calculations-NEW-lyear peak time (hrs) 11.930 volume (cy) 4830.413 OUTPUT: Routing Method: storage-indication Hydrograph 0 Routing Summary of Peaks: 1-yr 24-hr Peak SCS TR-55 Storm Event inflow (cfs) 11.588 at 11.94 (hrs) discharge (cfs) 0.872 at 12.58 (hrs) water level (ft) 493.304 at 12.64 (hrs) storage (cy) 839.957 Hydrograph 1 Routing Summary of Peaks: 2-yr 24-hr Peak SCS TR-55 Storm Event inflow (cfs) 12.594 at 11.94 (hrs) discharge (cfs) 0.913 at 12.54 (hrs) water level (ft) 493.517 at 12.64 (hrs) storage (cy) 904.682 Hydrograph 2 Routing Summary of Peaks: 10-yr 24-hr Peak SCS TR-55 Storm Event inflow (cfs) 22.564 at 11.94 (hrs) discharge (cfs) 7.816 at 12.10 (hrs) water level (ft) 494.697 at 12.10 (hrs) storage (cy) 1286.407 Hydrograph 3 Routing Summary of Peaks: 100-yr 24-hr Peak SCS TR-55 Storm Event inflow (cfs) 41.828 at 11.94 (hrs) discharge (cfs) 40.672 at 11.96 (hrs) water level (ft) 494.998 at 11.96 (hrs) storage (cy) 1391.520 Thu Jun 25 09:40:28 EDT 2015 Page 3 Subarea B Routing Calculations-NEW-lyear BasinFlow printout INPUT: Basin: Subarea B Routing Calculations 4 Contour Areas Elevation(ft) Area(sf) Computed vol . (cy) 492.50 3829.00 0.0 494.00 4509.00 231.4 496.00 6108.00 623.1 498.00 7869.00 1139.4 Start_Elevation(ft) 492.50 Vol . (cy) 0.00 4 Outlet Structures Outlet structure 0 orifice name: Orifice area (sf) 0.196 diameter or depth (in) 6.000 width for rect. (in) 0.000 coefficient 0.500 invert (ft) 493.500 multiple 1 discharge into riser Outlet structure 1 Wei r name: Riser diameter (in) 24.000 side angle 0.000 coefficient 3.300 invert (ft) 495.700 multiple 1 discharge into riser transition at (ft) 0.608 orifice coef. 0.500 orifice area (sf) 3.142 Outlet structure 2 Culvert name: Barrel multiple 1 discharge out of riser D (in) 15.000 h (in) 0.000 Length (ft) 48.000 Slope 0.005 Manning's n 0.013 Inlet coeff. Ke 0.500 Equation constant set 3 Invert (ft) 492.500 Outlet structure 3 weir name: Emergency Spillway length (ft) 45.000 side angle 63.430 coefficient 3.000 invert (ft) 496.700 multiple 1 discharge through dam Page 1 Subarea B Routing Calculations-NEW-lyear 4 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 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: 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 Page 2 Subarea B Routing Calculations-NEw-lyear 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) 1.406 at 12.34 (hrs) water level (ft) 495.758 at 12.34 (hrs) storage (cy) 569.281 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) 2.492 at 12.22 (hrs) water level (ft) 495.862 at 12.22 (hrs) storage (cy) 592.095 Hydrograph 2 Routing Summary of Peaks: 10-yr 24-hr Peak SCS TR-55 Storm Event inflow (cfs) 17.273 at 11.98 (hrs) discharge (cfs) 11.079 at 12.10 (hrs) water level (ft) 496.605 at 12.10 (hrs) storage (cy) 765.625 Hydrograph 3 Routing Summary of Peaks: 100-yr 24-hr Peak SCS TR-55 Storm Event inflow (cfs) 33.975 at 11.98 (hrs) discharge (cfs) 33.377 at 12.00 (hrs) water level (ft) 496.992 at 12.00 (hrs) storage (cy) 862.969 Thu Jun 25 09:30:03 EDT 2015 Page 3 ,, 1 . ,i i14n. . ' - q.17 ) .q G• -----T1.1 t : . i , :N *7) :%° j 6)/0(10 41\f"f5 )i A elkil I ty(9 vitplAi!Mi_ii, n .' --------7 , , , All h V'SS'0 f 0j9 I 0-- 1 4 '11J + Sg 1 SS.q ,j 1 5b)(r;e* 0) 1. c., 4....e'7,.s-) .., _ is9fell -- --z - ‘. -_, c_ s• ci ._:_ 19161-m t.e •= 01-vlierc ,,..„._ Li ,--- s ,..... o , 1-, e, -f .Q- (7....., tci--3-7.---t, ) .- -.:›Nitivisjii . 1, 44 _:,,... / 3„) -.c ri -75). wc _s t. 1 (t)i I (-) 1 tlie) g x r Q j ' WC L il 1 - vNis fro If. ---)ii Ark-- J.,() ) i _-_-_-1414 _::) _4 • ....,.... / cl \ -.;, :, 1.3 c -_. -570 ./ (_) > 7: 4, ,' - 901-i1 4 4_ 1 i :.# 1 1(--% t q 4(1 00 , la i ,,'-, .' 16C " ' 110 c: C ___ 4.....•••••......moramme. 7 )1-/ 4.4 3 S t47.1 !,01 e) _.. •,i -. .,-) 192): fx... \ I 4 r-tewi ir t i -,.. .....„ _ : i , •-' • . .---.,:i't I • , --0-1./ , i ' ' 7r. • . ..)- (•-m- - k -_.. --)=7------------ ICI t1, ei s ..71‘.)-' I 3*Aci lirkkirrj - 4e) .17f1-)IN lilifYiT 11 'vIllu ' irA,