Loading...
HomeMy WebLinkAboutSDP200000130 Calculations Stormwater Management Plan 2001-04-21 t_ Stormwater&BMP Analysis Millstone of Ivy March 26, 2001 Revised: April 21, 2001 Susan A. Riddle,P.E. Millstone of Ivy Proposed BMP: Water Quality Swale as shown on the plans. All roof drains are to be piped to the Water Quality Swale ponding area. All new impervious areas will be picked up by the Water Quality Swale EXCEPT for a small section of the entrance drive and the Sidewalk at the rear of the proposed building. BMP Computation attached. Required Water Quality Swale Surface Area: 397.55 sq. Ft. Provided Water Quality Swale Surface Area: 504 sq. Ft. Proposed Stormwater Management: Stormwater has been routed through the BMP for detention. —SEE attached calculations. According to the routing calculations,there is minimal, if any, outflow from the BMP up to and including the 100-year storm. Stormwater&BMP Analysis Albemarle County Water Protection Ordinance: Modified Simple Method Millstone of Ivy April 21. 2001 Plan: Millstone of Ivy Preschool Water Resources Area Rivanna Reservoir&Ivy Creek Preparer: Susan A.Riddle,P.E. Date: 11-Mar-01 REVISED: APRIL 21,2001 Revised to include IMP 58-37C in Project Drainage Area Project Drainage Area Designation DA T.M-P.58-37C L storm pollutant export in pounds, L=[P(Pj)Rv/12][C(A)2.72] Rv mean runoff coefficient, Rv=0.05+0.009(1) Pj small storm correction factor,0.9 I percent imperviousness P annual precipitation,43"in Albemarle __ _ A project area in acres in subject drainage area, A= L� -2:59 :Acres 112646 SQ.FT. C pollutant concentration,mg/I or ppm target phosphorus f factor applied to RR ✓ required treatment volume in cy,0.5"over imperv.area= A(I)43560(0.5/12)27 RR required removal, L(post)-f x L(pre) %RR removal efficiency, RR100/L(post) Impervious Cover Computation(values in feet&square feet) µ_ Item -..__.__.___._._-.._._..._______...__.-,__.w__.....____. _1 pre7develontent_ -___-_-----•- . _ t�evebpmeM-______._.____._____..�._.___. _ I Roads LengthWidth subtotal I �� - Le -_ _ ' _ n�Ui_`Width subtotal , EX.LOBBAN PLACE; 0: 0.: 1200< < EXISTING. 01 01 1200 ! I i L !?tV_ _ _ 0 Qj Q, 0 --0 -- 0: _ Driveways ,Lengtfi_ Width no. subtotal I Length__.. Width no. subtotal I , and walks .____....__.__.Oi______..__._OI._..______PL.________P 0` 0' __0: 7211 j ,_._.._.._..._._.___. _... 0' 0 01 - - t •Parking Lots 1 2 3 4. j� _ 1 2 3 41 ___ < OI 3900? 0 Gravel areas _ Area __ t IArea4 I Ix 0.70= _.j_ 0( f._..-_ ix 0.70■ I 0 Structures Area no. subtotal 1 -1.- Area no. subtotal _• ;._._______..0�____._6 . 0 I { 3038: 1! 3036s 0_ 0 0 [ 0' 0; 0: 0' of 0; 0 L.._.. _..1.... _ _O ._.. Actively-grazed pasture& Area 1 Area ; yards and cultivated turf -lilt 0.08= i 0 j 0 x 0.08= 0' 2 5 Acre Residences Area k Area I V--- .i rn Woodlands ; 111446 x 0.05= �...._____._.. 5572.308; .__ i 103495x 00`� ._-. 5174.758 'Other Impervious Areas . 1 ; --_. .__-1 s 0: , 0 Impervious Cover _ " "' 6% _ 13Xt l(Pre) l(post) Rv(posq'y__V._^' 0.16 i _.. 22.1 New Development(For Development Areas,existing impervious cover<=20%) C f I(pre)' Rv(pre) L(pre) L(Post) RR I %RR ' Area Type _._. ___. 0.70 1.00 20%' 0.23 3 65 2.61 -1.04 f -40% Development Area 0.10 • 0.83 1.31 0.48 37% Drinking Water Watersheds 0.40 1.00 1% 0.10 : 0.94 : 1.49 0.55 37%:Other Rural Land •min.values TOTAL IMPERVIOUS AREA TO Water Quality Swale (SQ.FT.) 7951 REQ'D REMOVAL RATE:37%:WQ SWALE PROPOSED: REQUIRED SURFACE AREA=5°, 0.05 (SQ.FT.) 397.55 Stormwater&BMP Analysis Millstone of Ivy March 26, 2001 Susan A. Riddle,P.E. =at Tonal Formula ,0 p04.9.P05C-O rYl p Area Number )_ Area (ar ) CA 1 0. 900 0. 007 °• C"--)6 S,t o ALS 17 , 2 0. 900 0. 106 0. 095 3 0.900 O. 070 0. 063 - 'w1 113 4 0. 350 0. 107 C). 037 leighted Totals: 0. 697 0. 290 0. 202 Time of concentrat ion= 5 min Period od Intensity Peak Flow ow (years) C in/hr ) (c fs) ' 5. 40 1. 09 5 6. 35 1 . 28 10 7. 10 1 . 44 25 8. 00 1 . 62 50 8. 90 1 . 80 1C)0 9. 60 1 . 94 iydr�igraph --re) l3ry lP Time of concentration = 5.0 min 3tarm duration = 5. 0 min Time 02 05 010 025 050 0100 min:) (c fs) (r fs) (c fs) Cc fs) (c fs) (c fs) 0. 0 0. 00 0. 00 0. 00 0. 00 0. 00 C).00 1 . 0 0. 22 0. 26 0. 29 0. 32 0. 36 0. 39 . 0 0. 44 C). 51 0. 57 0. 65 C). 72 0. 78 3. C) 0. 65 0. 77 0. 86 C). 97 1 . 08 1 . 16 4. 0 0. 87 1 . 03 1 . 15 1 . 29 1 . 44 1 . 55 5. 0 1 . 09 1 .28 1 . 44 1. 62 1 . 80 1 .94 6. 0 0. 96 1 . 13 1 . 26 1 . 42 1 . 58 1 .71 7. 0 0. 83 0. 98 1. 09 1 . 23 1 . 37 1 . 48 8. 0 0. 70 0. 82 0. 92 1 . 04 1 . 15 1 .24 9. C) 0. 57 C). 67 0. 75 C). 84 C). 94 1 . 01 1C).0 0. 44 0. 51 0. 58 C). 65 0. 72 C).78 11 .0 0. 31 0. 36 0. 40 0. 46 0. 51 0. 55 12. 0 0. 18 0. 21 0. 23 0. 26 0. 29 0. 31 13. 0 0. 05 0. 05 0. 06 0. 07 0. 08 0. 08 Stormwater& BMP Analysis Millstone of Ivy March 26, 2001 Susan A. Riddle,P.E. *******-**x.***.*..*.*.**:*.*******************************************-************** * ROUT VERSION 5. 4 ** PROJECT: MILLSTONE BMP 2-YEAR ** DATE: 3/23/2001* .*.*-***************-*******************************-****************************** ::Types: 1 : Weir ; 2: Pipe; 3: Riser ) Structure 1 Structure 2 Structure 3 1 : Type 3: Riser 3: Riser 3: Riser •Jeir : 2: Elevation ( ft) 0. 00 0. 00 0. 00 3: Length ( ft ) 0. 00 0. 00 0. 00 4: Coefficient 0. 00 0. 00 0.00 Riser : 5: Elevation ( ft ) 683. 10 683. 10 683. 10 6: Diameter (in) 6. 00 6. 00 6.00 7: Orifice Elevation ( ft ) 0. 00 0. 00 0. 00 8: Orifice Diameter ( in) 0. 00 0. 00 0.00 9: Orifice Elevation ( ft) 0. 00 0. 00 0. 00 10: Orifice Diameter ( in) 0. 00 0. 00 0. 00 11 : Orifice Elevation ( ft ) 0. 00 0. 00 0. 00 12: Orifice Diameter ( in) 0. 00 0. 00 0.00 Pipe: 13: Invert Elevation ( ft ) 678. 60 678. 60 678. 60 14: Diameter (in) 6. 00 6. 00 6. 00 15: Orifice Diameter ( in) 6. 00 6. 00 6. 00 16: Length ( ft) 24. 00 24. 00 24. 00 17: Manning's n 0. 010 C). 010 C). 010 18: Slope ( ft/ft) 0. 010 0. 010 0. 010 19: Entrance Lass Coefficient 0. 5 0. 5 0. 5 Surface: 20: Initial Elevation ( ft) 682. 05 Storage Pond Characteristics: Section Elevation Area (ft ) (sq ft ) 1 681 . 99 0. 00 2 682. 00 504.00 3 683. 00 1380.00 Control : RW = Riser acting as a weir RO = Riser acting as an orifice PI = Horizontal pipe in inlet control PO = Horizontal pipe in cutlet control Time Inflow Riser Riser Riser Total Elev Storage (min) (cfs) (cfs) (cfs) (cfs) (cfs) ( ft) (cu ft) 0. 0 0. 00 0. 0 0. 0 0. 0 0. 00 682. 05 25. 16 1 . 0 0. '22 0. 0 0. 0 0. 0 0. 00 682.06 28.81 2.C) C). 44 0. 0 0. 0 0. 0 0. 00 682. 09 48. 94 . 0 0. 65 0. 0 0. 0 0. 0 0. 00 682. 14 82. 35 4. 0 0. 87 0. 0 0. 0 0. 0 0. 00 682.20 128. 88 5. 0 1 . 09 0. 0 0. 0 0. 0 0. 00 682. 28 188. 47 6. 0 0. 96 0. 0 0. 0 0. 0 0. 00 682. 35 250. 50 7. 0 0. 83 0. 0 0. 0 0. 0 0. 00 682. 41 304. 49 8.0 0. 70 0. 0 0. 0 0. 0 0. 00 682. 46 350. 53 9. 0 0. 57 0. 0 0. 0 0. 0 0. 00 682. 49 380. 85 10.C) 0. 44 0. 0 C). 0 0. C) C). 00 682. 51 4,05. 05 11 . 0 0. 31 0. 0 0. 0 0. 0 0. 00 682. 53 423. 02 12. 0 0. 18 0. 0 0. 0 0. 0 0. 00 682.54 434. 70 13. 0 0. 05 0. 0 0. 0 0_ n r r,r, c o J CC i .i Stormwater& BMP Analysis Millstone of Ivy March 26, 2001 Susan A. Riddle,P.E. ****.*****•*******•*• ****•*.-*********•*•*•****•**** **•*****•***•****•****************•**** * ROUT VERSION 5. 4 ** PROJECT: MILLSTONE BMP 10-YE: ** DATE: 3/23/2001* ***************************************-*************************************** (Types: 1 : Weir ; 2: Pipe; 3: Riser ) Structure 1 Structure 2 Structure 3 1: Type 3: Riser 3: Riser 3: Riser Weir : Elevation ( ft ) 0. 00 0. 00 . 0), 00 3: Length ( ft) 0. 00 0. 00 0. 00 4: Coefficient 0. 00 0. 00 0. 00 Riser : 5: Elevation ( ft ) 683. 10 683. 10 683. 10 6: Diameter (in) 6. 00 6. 00 6. 00 7: Orifice Elevation ( ft ) 0. 00 0. 00 0. 00 8: Orifice Diameter ( in) 0. 00 0. 00 0. 00 9: Orifice Elevation ( ft ) 0. 00 0. 00 0. 00 10: Orifice Diameter (in) 0. 00 0. 00 0. 00 1 1 : Orifice Elevation ( ft ) 0. 00 0. 00 0. 00 12: Orifice Diameter ( in) 0.00 0. 00 0.00 Pipe: 13: Invert Elevation ( ft ) 678. 60 678. 60 678. 60 14: Diameter ( in) 6.00 6. 00 6.00 15: Orifice Diameter ( in) 6. 00 6. 00 6. 00 16: Length ( ft) 24. 00 24. 00 24. 00 17: Manning's n C). 010 0.010 0. 010 18: Slope ( ft/ft) 0.010 0. 010 0. 010 19: Entrance Loss Coefficient 0. 5 0. 5 0. 5 Surface: 20: Initial Elevation ( ft ) 682. 05 Storage Pend Characteristics: Section Elevation Area ( ft) (sq ft) 1 681 .99 0.00 2 682.00 504.00 683.00 1380.00 Control :: RW = Riser acting as a weir RO = Riser acting as an orifice PI = Horizontal pipe in inlet control PO = Horizontal pipe in outlet control Time Inflow Riser Riser Riser Total Elev Storage (min) (cfs) (cfs) (cfs) (cfs) (cfs) (ft ) (cu ft) 0. 0 0. 00 0. 0 0. 0 0. 0 0. 00 682. 05 25. 16 1 .0 0. 29 0. 0 0. 0 0. 0 0. 00 682. 06 29. 98 2.0 0. 57 0. 0 0. C) 0. C) 0. 00 682. 10 56. 55 3. ci 0. 86 0. 0 0. 0 0. 0 0. 00 682. 17 100.52 4.0 1 . 15 0. 0 0. 0 0. 0 0. 00 682.25 161 . 67 5.0 1 . 44 0. 0 0. 0 0. 0 0. 00 682. 34 239. 99 . ' 6. 0 1 . 26 0. 0 0. 0 0. 0 0. 00 682. 43 321 . 52 7. 0 1 . 09 0. 0 0. 0 0. 0 0. 00 6$2. 50 392. 47 8.0 0. 92 0. 0 0. 0 0, C) 0. 005-681. J6 4J.�. r�9 9. 0 0. 75 0. 0 0. 0 0. 0 0. 00 682. 60 493. 77 10. 0 0. 58 0. 0 0. 0 0. 0 Q0. 00 682. 63 526. 28 11 .0 0. 40 0. 0 0. 0 0. 0 0. 00 682.65 550.42 12. 0 0. ' 3 0. 0 0. 0 0. 0 0. 00 682.67 566. 11 Stormwater&BMP Analysis Millstone of Ivy March 26, 2001 Susan A. Riddle,P.E. #******************x.*..*.={*******-?.a?s. #. c_cx-?E*#-3E#-7F*?F iF#*** * -****:•*** **** t-**** •*#** •* ROUT VERSION 5. 4 ** PROJECT: MILLSTONE BMP 100-YR ** DATE: 3/23/2001* *****-*****.******************************************************************** (Types: 1 : Weir ; 2: Pipe; 3: Riser ) Structure 1 Structure 2 Structure 3 1 : Type 3: Riser 3: Riser 3: Riser Weir : 2: Elevation ( ft ) 0. 00 0. 00 0. 00 3: Length ( ft ) 0. 00 . 0. 00 0. 00 4: Coefficient 0. 00 0. 00 0. 00 Riser : 5: Elevation ( ft ) 683. 10 683. 10 683. 10 6: Diameter (in) 6. 00 6. 00 6. 00 7: Orifice Elevation ( ft) 0. 00 0. 00 0. 00 8: Orifice Diameter ( in) 0. 00 0. 00 0. 00 9: Orifice Elevation ( ft) 0. 00 0. 00 0.00 10: Orifice Diameter (in) 0. 00 0. 00 0. 00 11 : Orifice Elevation ( ft ) 0. 00 0. 00 0.00 12: Orifice Diameter (in) 0. 00 0. 00 0. 00 Pipe: 13: Invert Elevation ( ft ) 678. 60 678. 60 678.60 14: Diameter (in) 6. 00 6. 00 6. 00 15: Orifice Diameter ( in) 6. 00 6. 00 6. 00 16: Length (ft) 24. 00 24. 00 24. 00 17: Manning' s n 0. 010 0. 010 0. 010 18: Slope ( ft/ft ) 0. 010 0. 010 0. 010 19: Entrance Lass Coefficient 0. 5 0. 5 0. 5 Surface: 20: Initial Elevation (ft ) 682. 05 Storage Pond Characteristics: Sect ion Elevation Area ( ft) (sq ft ) 1 681 . 99 0. 00 .2 682. 00 504. 00 3 683. 00 1380. 00 Control : RW = Riser acting as a weir RO = Riser acting as an orifice P'I = Horizontal izc ontal pipe in inlet control PO = Horizontal pipe in outlet control Time Inflow Riser Riser Riser Total Elev Storage (min) (cfs) (cfs) (etc) (cfs) (cfs) ( ft ) (cu ft) 0. 0 0. 00 0. 0 ci. 0 0. 0 0. 00 682.05 25. 16 1 . 0 0. 39 0. 0 0. 0 ci, i0 0. 00 682. 06 31 . 73 2.0 0. 78 0. 0 0. 0 0. 0 0. 00 682. 12 67. 80 3.0 1 . 16 0. 0 0. 0 0. 0 0. 00 682. 20 127. 26 4. 0 1 . 55 0. 0 0. 0 0. 0 0. 00 682. 30 209. 89 5. 0 1 . 94 0. 0 0 0. 0 0 0. 0 0 0. 00 i 682. 42 315.72 6. 0 1 . 71 0. 0 0. 0 0. 0 0. 00 682. 53 425. 88 7.0 1 . 48 0. 0 0. 0 0. 0 0. 00 682. 63 521 . 79 8. 0 1 . 24 0. 0 0 0. 0 0. 0 0. 00 682. 70 603. 59 9. 0 1 . 01 0. 0 0. 0 0. 0 0. 00 682. 76 -671 . 36 10. 0 0. 78 0. 0 0. 0 0. 0 0. 00 682. 80 716. 31 11 . 0 0. 55 55 0. 0 0. 0 0. 0 0. 00 682. 83 749. 66 12. 0 0. 31 0. 0 0. 0 0. 0 n_ nn g-s:1 sus -7-71