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HomeMy WebLinkAboutSDP200500136 Calculations 2006-08-181Aq John Mc Nair and-A Con.whmg bigmteers L B R B. Building Waynesboro, Vir; 229511 540 -942 -1161 • FAX: 540 -942 -1163 • G -MAIL: jnnvubruchcum.com DETENTION and STORM DRAIN CALCULATIONS for Westfield 10 -25 -05 Revised 8 -18 -06 (Add Seal, Revise Pipe Sizes) DAVID L COLLIN N®. 030387 Z �; ALS! David L. Collins, P.E., L.S. D L. B. & B. Building, Waynesboro Virginia 22980 _ 540 -942 -1161 • FAX: 540 -942 -1163 • E -MAIL: jma(abrucheum.com Johl -- svociates , Consulting Engineers Stormwater Treatment: Based on the Albemarle County Ordinance: 17- 314 -F -4 it was determined that the site is exempt from stormwater detention. Requirements for stormwater quality are met using Filterra® Stormwater Bioretention Filtration System. The stormwater runoff that will be going through the biofilters will then be discharged from the site at structure A -5. All off -site runoff from the Northeast bypasses the site via existing concrete curbing on the adjoining parcel and along Westfield Road. All off -site runoff from the Northwest drains onto the site and is collected in structure A -6 to allow it to pass through the site. All off -site runoff to the Southeast and Southwest is down slope from the site and do not contribute any runoff to the site. We have included the 2, 10, 25, and 100 year storm calculations for the pipe system. The site was initially designed with detention; we have included and retained this design information at the end of this report under the "Preliminary Detention Calculations" heading. Short Version BMP Computations For Worksheets 2 - 6 Albemarle County Water Protection Ordinance: Modified Simple Method Plan: Westfield Road Site Water Resources Area: Development Area Preparer: NV Date: 23- Sep -05 Project Drainage Area Designation DA #1 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) Pi small storm correction factor, 0.9 1 percent imperviousness P annual precipitation, 43" in Albemarle A project area in acres in subject drainage area, A = 0.55 C pollutant concentration, mg /I or ppm target phosphorus f factor applied to RR V required treatment volume in cy, 0.5" over imperv. area = A(1)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) Item pre - development Area post - development Area Roads Length Width subtotal Length Width subtotal 0 0 0 0 0 0 0 0 0 0 Driveways Length Width no. subtotal Length Width no. subtotal and walks 0 0 0 0 0 0 0 0 Parking Lots Area 1 Area 2 Area 3 Area 4 Area 1 Area 2 Area 3 Area 4 0 12783.54 12783.54 Gravel areas Area 1 Area 2 subtotal Area 1 Area 2 subtotal 0 x0.70= 0 0 x0.70= 0 Structures Area no. subtotal Area no. subtotal 0 3731.02 1 3731.02 0 0 0 0 0 3731.02 Actively - grazed pasture & Area Area yards and cultivated turf 23868.66 x 0.08 = 1909.493 7354.1 x 0.08 = 588.328 Active crop land Area Area x0.25= 0 x0.25= 0 Other Impervious Areas Area 1 Area 2 Area 3 Area 1 Area 2 Area 3 0 0 0 Impervious Cover 8% 72% I(pre) I(post) Rv(post) V 0.69 26.4 New Development (For Development Areas, existing impervious cover <= 20 %) C f I (pre) * Rv(pre) L(pre) L(post) RR % RR Area Type 0.70 1.00 20% 0.23 0.77 2.34 1.56 67% Development Area 0.35 1.00 0% 0.12 0.21 1.17 0.96 82% Drinking Water Watersheds 0.40 1.00 1% 0.12 0.23 1.34 1.10 82% Other Rural Land * min. values Redevelopment (For Development Areas, existing impervious cover > 20 %) C f I (pre) * Rv(pre) L(pre) L(post) RR % RR Area Type 0.70 0.90 20% 0.23 0.77 2.34 1.64 70% Development Area 0.35 0.85 0% 0.12 0.21 1.17 0.99 85% Drinking Water Watersheds 0.40 0.85 1% 0.12 0.23 1.34 1.14 85% Other Rural Land rev. 30 May 2002 JMK David L. Collins, P.E., L.S. John McNair & Assoc. 109 South Wayne Avenue Waynesboro, Virginia 22980 (540) 94 -1161 (540) - 94 2-116 3 FAX November 22, 2005 Plan Review of Filterra Westfield Project, Albemarle County Dear Sirs Thank you for submitting the partial plans for our review of the Westfield project. Filterra' structures A3(8'x4') and A4(6'x6') were studied for; • Planned Filterra® box size • Filterra® contributing drainage area meeting project's regional sizing specification • Spot elevations (TC) for Filterra® and bypass relief • Filterra® invert elevations are 3.5' below TC • The bypass is lower than the Filterra® elevation (spot elevations) • The grading pattern encourages cross linear flow and not head -on flow • The Filterra® outlet drain pipe is sized correctly and exits perpendicular to the wall • For any conflicting structures such as storm drain pipes below Filterra® • For most efficient placement of Filterra® units • 4 -6" opening throat detail and standard notes on plans The plan review concluded that the Filterra` structures listed above were sited and sized appropriately to treat stormwater to our published specifications. Operational consistency with these specifications is contingent upon the stormwater units being installed correctly and according to the plans, as well as regular maintenance being performed. Installation Help documents will be forwarded to the Buyer at time of order. The Filterra Installation, Operation and Maintenance Manual will be forwarded to the Owner when the units are activated by Americast. Yours sincerely Dean Baddorf Filterra® Stormwater Bioretention Filtration System Manufactured by Americast T: (804) 798 -6068 ICI /�1CJ ERI�n [ff 11352 Virginia Precast Road F: (804) 752 -6838 Ashland, VA 23005 E: designLfilterra.com xvww.filterraxom 2--m John MtAaix-ajut- 4ssociatcs ('cut Engbiecrs L. B. c , B. Bui 'A' bororgrnia 2298 x411 -942 -1 11 1 • FAX: X40 -942 -1 103 • F- MAIL: jma Ir bruchrum.cum Miscellaneous Calculations Pha view 21 1 . - lot ,_Di M� page 1 Storm Sewer Tabulation Ruoff re Up Pipe Invert Elev Vel Len Drng Area Area x C Tc Rain Total Cap (1) flow full Dn Station coeff Size Slope Incr Total Incr Total Inlet Syst (ft) (ft) Line To (min) (min) (inthr) (cfs) (cfs) (fUs} (in) ( %) Line (C) HGL Elev Grnd I Rim Elev Up Dn Up Dn {ft) (ft) (ft) (ft) Line ID (ft) (ac) lac) 00 0.00 1.27 0.0 5.4 5.1 6.43 11.10 5.33 18 1.12 439.70 439.50 440.67 440.47 0.00 1 96.3 0.97 0.97 0.90 0.87 4.52 7.09 4.44 15 1.20 441.11 439.95 441.96 441.11 0.00 1 End 17.9 0.00 1.41 0. 0.87 5.0 5 0 52 2 5.2 2,05 6.52 315 15 1.02 440.51 440.34 441.09 441.11 0.00 1 3 1 16.7 0.44 0.44 0.90 0.40 0.40 5.0 5.0 Number of lines: 3 Project File: 205186- STORM.st Inlet time + 10.50) ^ 0 2; Return period = 2 Yrs. NOTES: Intensity = 49.02 ! 0.00 0.00 0.00 Run Date: 08 -19 -2006 HydraROw Storm Sewers 2003 page i Inlet Report Line inlet 10 No 1 2 3 Gutter Q Junc Curb Inlet Grate Inlet So W Sw Sx W wft} (eft) Q = Q Q b type area t (ft) CIA carry capt Yp Nt (ft Rift ( ) ) (sgft) (ft) (ft) BYp inlet line Dep No spread depth spread (in) n depth I (ft) (ft) (ft) (in) 0.0 (cis) (cfs) (cfs) (cfs) 0,000 0.000 0.00 Sag 0.00 0.000 0.00 0.00 0.00 11.211 2.35 MH 0.0 0.00 1.20 0.140 0.100 000 0.0 0.000 0.00 .0 3.50 Sag 0.00 0.00 1.98 3.00 0,020 0.000 0.30 8.96 Grate 0.0 2 00 0.080 4.52 0.00 4.52 0.00 p.00 0.00 0.00 Sag 2.05 D.00 2.05 0.00 Curb 3.5 8,00 0.00 0.00 0.00 Off 0.8 2 2.35 0.00 Off 0.35 8.96 2.00 Off Run Date: 08- 19-2006 I_p -F File: Albemarle -IDF HDA 05 03.IDF Project Flle; 205186 STORM.stm Inlet time + 10.50) 0.8 Return period = 2 Yrs. ; 49.021 ( NOTES: Inlet NValues = 0.016 ; Intensity = - - Number of lines: 3 Known 0 added ers 20C HYdraflow Storm Sew Hydraulic Grade Line Computations Page 1 Line Size Q Downstream Len Upstream Check JL Minor coeff loss Invert HGL Depth Area Vel Vel EGL Sf Invert HGL Depth Area Vel EGL S Ave Enrgy elev elev head elev elev elev TV head elev S loss (in) (cfs) (ft) (ft) (ft) (sgft) (ft/s) (ft) (ft) M (ft) (ft) (ft) (ft) (sgft (ft) (ft) M (ft) (K) (ft) 1 18 6.43 439.50 440.47 0.97 1.21 5.33 0.44 440.91 0.669 17.9 439.70 440.67 0.97" 1.21 5.33 0.44 441.11 0.669 0.669 n/a 1.00 0.44 2 15 4.52 439.95 441.11 1.16 1.19 3.81 0.23 441.33 0.424 96.3 441.11 441.96 0.85" 0.89 5.08 0.40 442.36 0.753 0.589 n/a 1.00 0.40 3 15 2.05 440.34 441.11 0.77 0.79 2.59 0.10 441.21 0.207 16.7 440.51 441.09 0.58 0.55 3.71 0.21 441.30 0.534 0.370 0.062 1.00 I 1 0.21 Project File: 205186- STORM.stm Number of lines: 3 Run Date: 08 -19 -2006 j NOTES: ` Normal depth assumed., " Critical depth assumed. Hydraflow Storm Sewers 2003 -qfnrm Rp-wp-r Profile Proj. file: 205186-STC)RM-stm Elev. (ft) 452.00 �— - r - -� - -- -- 449.00 Ln: 446.00 t 18 (in) 443.00 440.00 437.00 0 10 20 30 40 50 60 70 80 90 100 110 120 Reach (ft) Hydratlow Storm Sewers zuu.5 Hydraflow Plan View 2 3 1 OutfaN Project file: 205186- STORM.stm No. Line�3 Hydra low Storm Sewers 2003 Stor Sewe Su mmary Report Lit Nc Proi NO Page 1 if Line ID Flow Line Line Invert Invert Line HGL HGL Minor Dns rate size length EL Dn EL Up slope down up loss line (cfs) (in) (ft) (ft) (ft) (ft) (ft) No. 8.33 18 c 17.9 439.50 439.70 1.117 440.60 440.80 0.56 End 5.82 15 c 96.3 439.95 441.11 1.205 441.36 442.08 0.51 1 2.64 15 c 16.7 440.34 440.51 1.020 441.36 441.35 0.14 1 ect File: 205186- STORM.stm Number of lines: 3 Run Date: 08 -18 -2006 'ES: c = circular; e = elhptical; b = bo>< Return period = 10 Y - Indicates surcharge condition. Hydraflow Storm Sewers 2003 Page 1 Storm Sewer Tabulation Rnoff re Size Slope Vel Pipe Invert Elev Area x C Tc Rain Total Cap Len Drng Area (1) flow full U Dn Station coeff Incr Total Incr Total Inlet Syst N (ft) (ft) Line Line To cfs) (cfs) (ftls) (� fn ) HGL Elev Grnd I Rim Elev Up Dn UP Dn (ft) (ft) (ft) (ft) Line ID (ft) (ac) (ac) (C) (min) (min) (in/hr) .00 0.00 1.27 0.0 5.3 6.6 8.33 11.10 5.99 18 1.12 439.70 439.50 440.80 440.60 0.00 6.7 5.82 7.09 5.22 15 1.20 441.11 439.95 442.08 441.36 0.00 1 End 17.9 0.00 1.41 0 1 2 1 96.3 0.97 0.97 0.90 0.87 0.87 5.0 5.0 6.7 2.64 6.52 2.74 15 1.02 440.51 440.34 441.35 441.36 0.00 3 1 16.7 0.44 0.44 0.90 0.40 0.40 5.0 5.0 Number of lines. 3 Protect File: 205186- STORM .st NOTES: Intensity = 46.95 / (Inlet time 9.50) " 0.73; t Return period = 10 Yrs. 0.00 0.00 0.00 Run Date: 08 -18 -2006 Hydraflow Storm Sewers 2003 Inlet Report Page 1 Line No Inlet ID Q = CIA (cfs) Q carry (cfs) Q capt (cfs) Q byp (cfs) Junc type Curb Inlet Grate Inlet Gutter Inlet Byp line No Ht (in) L (ft) area (sqft) L (ft) W (ft) So ( ft/ft) W (ft) SW (ft/ft) Sx (ft/ft) n depth (ft) spread (ft) depth (ft) spread (ft) Dep (in) 1 0.00 0.00 0.00 0.00 M 0.0 0.00 0.00 0.00 0.00 Sag 0.00 0.000 0.000 0.000 0.00 0.00 0.00 0.00 0.00 Off 2 5.82 0.00 5.82 0.00 Grate 0.0 0.00 1.98 3.00 3.50 Sag 1.20 0.140 0.100 0.000 0.33 2.87 0.33 2.87 0.00 Off 3 2.64 0.00 2.64 0.00 Curb 3.5 8.00 0.00 0.00 0.00 Sag 2.00 0.080 0.020 0.000 0.33 10.61 0.38 10.61 2.00 Off Project File: 205186- STORM.stm I -D -F File: Albemarle- IDF- HDA- 05- 03.IDF Number of lines: 3 Run Date: 08 -18 -2006 NOTES: Inlet N- Values = 0.016 ; Intensity = 46.95 / (Inlet time + 9.50) ^ 0.7 . Return =Yr, Known Q added Hydraflow Storm Sewers 2003 Page 1 Grade Line Computations Hydraulic Gra Len Downstream Sf Q Ve head l Vei EGL Line Size HGL Depth Area elev ( °! °} (ft) (ft) InveR ele ft} le (ft} (sgft) (Ells) (ft v (in) (cfs) 41 16 0.795 17. 0 97 1.02 5.71 6 0 218 0.036 1 442.58 0.56 4 442.08 0.26 1 5.99 441.11 4 14 441.49 444.60 110 0.812 96.3 0.88 3.01 8.33 439.50 0.35 441.71 441.35 0.84 1 18 1.25 1.23 4.74 16.7 440.51 439.95 441.36 441,45 3 15 2.64 440.34 441.36 0.169 2 15 5.82 1.07 2.46 0.09 1.0 Run Date! 08 -18 -2006 Number of lines: 3 NydraAOw Storm Sewefs zu Proje is F le'. 205186 STORM.stm depth assumed., "Critical depth assumed. NOTES ' Normal i `J JL M Minor Check Hoeft l loss Upstream A Sf Ave EnrgY th ( Area V Vel e Vet S EGL S Si E (K} (ft) invert e H D (sgft} ( (ft�s} ( ft (ft) (°J A le l (ft) ( n1a 1 40 0 0.56 0.56 1 441.36 p p 795 0 n 1.00 0 0.51 440.80 1 1.10 0 1.39 5 5.99 0 0.909 0 0. 0 g 439.74 0 0.5 1 1.00 0.14 0.56 4 442.08 0.26 1 5.99 441.11 4 14 441.49 444.60 110 0.812 96.3 0.88 3.01 8.33 439.50 0.35 441.71 441.35 0.84 1 18 1.25 1.23 4.74 16.7 440.51 439.95 441.36 441,45 3 15 2.64 440.34 441.36 0.169 2 15 5.82 1.07 2.46 0.09 1.0 Run Date! 08 -18 -2006 Number of lines: 3 NydraAOw Storm Sewefs zu Proje is F le'. 205186 STORM.stm depth assumed., "Critical depth assumed. NOTES ' Normal i `J Storm Sewer Profile Proj. file: 205186-STORM.stm Elev. (ft) 452.00 449.00 Ln: 2 446.00 15 Ln: 1 18 (in) 443.00 440.00 437.00 0 10 20 30 40 50 60 70 80 90 100 110 120 Reach (ft) Hydraflow Storm Sewers 2003 Storm Sewer Profile Proi. file: 205186-STORM.stm Elev. (ft) 452.00 449.00 446.00 ' (in) 443.00 440.00 437.00 0 10 20 30 40 50 60 70 80 90 100 Reach (ft) 1 (in) Hydraflow Storm Sewers 2003 Stor Se wer Summary Report Page 1 HydraFlOw Storm Sewers 2003 L ine Line ID Flow Line Line Invert Invert Line HGL HGL Minor Dns No. rate size length EL Dn EL Up slope down up loss line (cfs) (in) (ft) (ft) (ft) N (ft) (ft) (ft) No. 1 9.34 18 c 17.9 439.50 439.70 1.117 440.67 440.87 0.62 End 2 6.53 15 c 96.3 439.95 441.11 1.205 441.49' 442.47' 0.44 1 3 2.96 15 c 16.7 440.34 440.51 1.020 441.49 441.50 0.13 1 Project File: 205186- STORM.stm Number of lines: 3 Run Date: 08 -18 -2006 NOTES: c = circular; e = elliptical; b = box; Return period = 25 Yrs.; ' Indicates surcharge condition. HydraFlOw Storm Sewers 2003 Storm Sewer Tabulation Page 1 Station Len Drng Area Rnoff Area x C Tc Rain Total Cap Vel Pipe Invert Elev HGL Elev Grnd / Rim Elev Line ID coeff (I) flow full Line To Incr Total Incr Total Inlet Syst Size Slope Up Dn Up Dn Up Dn Line (ft) (ac) (ac) (C) (min) (min) (in /hr) (cfs) (cfs) (ft/s) (in) ( %) (ft) (ft) (ft) (ft) (ft) (ft) 1 End 17.9 0.00 1.41 0.00 0.00 1.27 0.0 5.3 7.4 9.34 11.10 6.33 18 1.12 439.70 439.50 440.87 440.67 0.00 0.00 2 1 96.3 0.97 0.97 0.90 0.87 0.87 5.0 5.0 7.5 6.53 7.09 5.32 15 1.20 441.11 439.95 442.47 441.49 0.00 0.00 3 1 16.7 0.44 0.44 0.90 0.40 0.40 5.0 5.0 7.5 2.96 6.52 2.68 15 1.02 440.51 440.34 441.50 441.49 0.00 0.00 Project File: 205186- STORM.stm Number of lines: 3 Run Date: 08 -18 -2006 NOTES: Intensity = 40.11 / (Inlet time + 7.75) ^ 0.6�, Return period = 25 Yrs. Hydraflow Storm Sewers 2003 Hydraulic Grade Line Computations Page 1 Line Size Q Downstream Len Upstream Check JL Minor coeff loss Invert HGL Depth Area Vel Vel EGL Sf Invert HGL Depth Area Vel Vel EGL Sf Ave Enrgy elev elev head elev elev elev head elev Sf loss (in) (cfs) (ft) (ft) (ft) (sgft) (f /s) (ft) (ft) (%) (ft) (ft) (ft) (ft) (sgft) (ft/s) (ft) (ft) (%) ( %) (ft) (K) (ft) 1 18 9.34 439.50 440.67 1.17 1.47 6.33 0.62 441.29 0.877 17.9 439.70 440.87 1.17 1.48 6.32 0.62 441.49 0.872 0.875 0.157 1.00 0.62 2 15 6.53 439.95 441.49 1.25 1.23 5.32 0.44 441.93 1.022 96.3 441.11 442.47 1.25 1.23 5.32 0.44 442.91 1.021 1.022 0.984 1.00 0.44 3 15 2.96 440.34 441.49 1.15 1.18 2.51 0.10 441.59 0.182 16.7 440.51 441.50 0.99 1.04 2.85 0.13 441.62 0.226 0.204 0.034 1.00 0.13 Project File: 205186- STORM.stm Number of lines: 3 Run Date: 08 -18 -2006 NOTES: ' Normal depth assumed., " Critical depth assumed. HydraFlow Storm Sewers 2003 Storm Sewer Profile Proj. file: 205186-STORM.stm Elev. (ft) 452.00 449.00 � i i � 446 Ln: 2 M Ln: 1 18 (in) 443.00 440.00 437.00 --- 0 10 20 30 40 50 60 70 80 90 100 110 120 Reach (ft) Hydraflow Storm Sewers 2003 Storm Sewer Profile Proj. file: 205186- STORM.stm Elev. (ft) 452.00 449.00 446.00 443.00 440.00 437.00 J 0 10 20 30 40 50 60 70 80 90 100 Reach (ft) i I , Hydraflow Storm Sewers 2003 1 ( (in) I I Hydraflow Storm Sewers 2003 Hydraflow Plan View 2 1 + Outfall Project fil e: 205186- STORM.stm No. Lines: 3 108 -18 -2006 Hydrafiow SlOrm Sewers X003 Page 1 Storm Sewer Tabulation Invert Elev Area x C Tc Rain Total Cap Vel Pipe Incr Total Rnoff (I) flow full Up Dn Station Len Drng Area coeff Size Slope Incr Total Inlet Syst Line (min) (min) (in/hr) (cfs) (cfs) (ftis) (in) N (ft) ( ft ) Line (C) HGL Elev Grnd ( Rim Elev Up Dn Up On (ft) (ft) (ft) (ft) Line ID (ft) (ac) (ac) 5.3 8.6 10.97 11.10 6.89 18 1.12 439.70 439.50 440.97 440.76 0.00 1 End 17.9 0.00 1.41 0.00 0.00 1.27 0.0 8.8 7.65 7.09 6.23 15 1 441.11 439.95 443.06 441.70 0.00 1 2 1 96.3 0.97 0.97 0.90 0.87 0.87 5.0 5-0 3.47 6.52 2.83 15 1.02 440.51 440.34 441.75 441.70 0.00 3 1 16.7 0.44 0.44 0.90 0.40 0.40 5.0 5.0 8.8 Number of lines: 3 Project File: 205186- STORM.st NOTES Intensity = 31 A9 / (1niet ti + 5.00) ^ 0.5 Return period = 100 Yrs. i' 0.00 0.00 0.00 Run Date 08 -19 -2006 Hydraflc- Storm Sewers 2003 Inlet Report Page 1 Line Inlet ID Q = Q Q Q Junc Curb Inlet Grate Inlet Gutter Inlet Byp No CIA carry capt byp type line Ht L area L W So W SW S n depth spread depth spread Dep No (cfs) (cfs) (cfs) (cfs) (in) (ft) (sqft) (ft) (ft) ( ft/ft) (ft) (ft/ft) (ft/ft) (ft) (ft) (ft) (ft) (in) 1 0.00 0.00 0.00 0.00 M 0.0 0.00 0.00 0.00 0.00 Sag 0.00 0.000 0.000 0.000 0.00 0.00 0.00 0.00 0.00 Off 2 7.65 0.00 7.65 0.00 Grate 0.0 0.00 1.98 3.00 3.50 Sag 1.20 0.140 0.100 0.000 0.52 4.69 0.52 4.69 0.00 Off 3 3.47 0.00 3.47 0.00 Curb 3.5 8.00 0.00 0.00 0.00 Sag 2.00 0.080 0.020 0.000 0.37 12.75 0.42 12.75 I 2.00 Off � Project File: 205186- STORM.stm I -D -F File: Albemarle- IDF7HDA- 05- 03.iDF - Number of lines: 3 Run Date: 08 -19 -2006 NOTES: Inlet N- Values = 0.016 ;Intensity = 31.09 / (Inlet time + 5.00) ^ f55; mourn period = 100 Y�a Known Q added I Hydraflow Storm Sewers 2003 JL minor Check coeft toss AVe EnrgY uta ti o ns Upstream EGL sf s f loss (K) (ft) Lin mp h ead ( ( (a) (ft) Gra Lin Co Len HGL Depth Area Vel cftid eft} Hydrau Invert elev ( (ms s) 0.74 1.00 �,i Downstream EGL Sf elev (ft) (ft) 1.039 0.186 Vet Vet (ft) (ft) 4.70 1.03 p.60 ea elev ( °la) 0 74 41 1.352 1.00 Q size Depth head (ft) 6.8 1.4 Line "GL � (ft} 1.27 i.59 443.66 1,40 p,12 invert elev ( ( 440.9 Q.60 0.046 1.00 elev (ft) (ft) 17.9 439.70 1.23 6.23 p.268 0279 in) cfs) (ft) 441.50 1.041 443.06 1.25 p.12 441.87 ( ( 6.90 0 74 96 3 441.11 1.23 2.83 1.26 1.59 1.40 441,75 1.24 440.7 0.60 442.31 44051 10.97 439.50 1.23 6.23 0.289 16.7 1 18 441.70 1,25 441.83 439.9 2,8 15 3.47 440.34 3 0.12 2 15 7.65 1,25 123 3 441.70 �- Run 0310'. 08- 19-,2006 Aiumber of l' e5 3 �ydrallow Storm Sewer J - 186�'T�RM stm th assumed• project Five, 205 Critical dep rieDth assumed., '� 7 - + � � � ^ � .. CA Evi � m w osDGn OF OUTLET PROTECTION FROM X ROUND PIPE FLOWING FULL mzwlMuM TAlLwATER CONDITION (T,-< 0.5 DIAMETER) Outlet u ~ D + L piv, Diameter, D --- | �op~ —L _—�� `�� n�5D �y` ' ailwater " ./. 20 lO 0 Recommended Muo' 4 a CD Lo O moo �a 00 3 s m 20 so � lno zmJ sno oisc»^roc. +t/`°". r PrOF0 � t' p K Ac Trapezoidal Ditch- 3:1 ,1'BOTTOM, RIPRAP Worksheet for Trapezoidal Channel Project Description Project File t: \jma projects \205186 - westfield rd \storm drainage \westfiel.fm2 Worksheet westfield Flow Element Trapezoidal Channel Method Manning's Formula Solve For Channel Depth Input Data Mannings Coefficient 0.040 Channel Slope 0.054000 ft/ft Left Side Slope 3.000000 H: V Right Side Slope 3.000000 H : V Bottom Width 1.00 ft Discharge 8.33 cfs --. Results Depth 0.64 ft . ---- -- Flow Area 1.87 ft Wetted Perimeter 5.05 ft Top Width 4.84 ft Critical Depth 0.72 ft Critical Slope 0.032829 ft/ft Velocity 4.45 ft/s Velocity Head 0.31 ft Specific Energy 0.95 ft Froude Number 1.26 Flow is supercritical. i X 50 c,? s e ('�O 08/19/06 Academic Edition FlowMaster v5.17 10:45 32 AM Haestad Methods. Inc. 37 Brookside Road Waterbury, CT 06708 (203) 755 -1666 Page 1 of 1 John- AkNair -uL d_Associaies Coll.enllin'> Ellgi ,ccr L. B. fi B BLIiIdln WGVnCCbo r1 % it -ini 22980 ;40 -942 -1161 • FAX: 340 -1)42 -1163 • E-MAIL: jnu,<< bruchcum.a,m Drainage Maps - IVA PL443.W 15 440 AS 4 SIAL-35 FVC CUTLET ME DILAMAGEAREA • 010 AC. (M 810FILTER A3 — DETAIL Q -11 SCALE 1'=4* 17 4 0 ! zx _j TCP-"3 90 L-.- rmvjN-PIo 11 40 1 oil INLET A2 — DETAIL X, BENCHMARK 42731 TOP OF FIRE HYDRAN7 NE CORNER OF WESTFIELD AND GREENBRIER TAKEN FROM HUFFMAN SITE PLAN. A V) Z V) > L.j X 'KI =GAq as LITE IPVG- a". �5600 cj h� 0� p AfN 7 FILTILI HIS (SEEDE R SPECURI EI-m FILTFRRA01110FILTER (su DETAILS& SPECUqICATIONS) Ls. ,4 Y-4 u L MAX w a QWTEK F WPARr% r 7mr 61-2$5 CV M DAVOCKMINERI TMr 6, -2a 5A Y, A CVAM DAVOCKMIkEMO-11 -w- Tmr 61 w-2-D-5n IM' M—T USE Mm CAL Cr ce THIS TOPOGRAPHIC SURVEY IS BASED UPON FIELD WORK PERFORMED ON JUNE 5, 1996 AND UPDATED ON AUGUST 15, 2005. 0, 20' 40 ISO CONTOUR INI VAL=I' Z ce UJ m uj < > O 1 u Z z o m < w 0 m u ce -j wj W -i LLI 1- ce Ln aW 0 Lei PROIJECT MO. 208186 DWG. DATE: 05-12-06 DESIGN BY: w DRAWN BY. w APPRMD. DLC SCALE: AS .070 SHEET NUMBER C3 OF 7 SHEETS N SA 4 WH 7 OP - 45. 4 9 u C, 'A c < rn LLS ra z -po wl qj U 4 4 0 LCII SPACE CAM TH op cl 44 DW L Mm -C.Lq - LE 'KI =GAq as LITE IPVG- a". �5600 cj h� 0� p AfN 7 FILTILI HIS (SEEDE R SPECURI EI-m FILTFRRA01110FILTER (su DETAILS& SPECUqICATIONS) Ls. ,4 Y-4 u L MAX w a QWTEK F WPARr% r 7mr 61-2$5 CV M DAVOCKMINERI TMr 6, -2a 5A Y, A CVAM DAVOCKMIkEMO-11 -w- Tmr 61 w-2-D-5n IM' M—T USE Mm CAL Cr ce THIS TOPOGRAPHIC SURVEY IS BASED UPON FIELD WORK PERFORMED ON JUNE 5, 1996 AND UPDATED ON AUGUST 15, 2005. 0, 20' 40 ISO CONTOUR INI VAL=I' Z ce UJ m uj < > O 1 u Z z o m < w 0 m u ce -j wj W -i LLI 1- ce Ln aW 0 Lei PROIJECT MO. 208186 DWG. DATE: 05-12-06 DESIGN BY: w DRAWN BY. w APPRMD. DLC SCALE: AS .070 SHEET NUMBER C3 OF 7 SHEETS �- Johi - -- �- CUZ1es ' Consulting Engineers I L. B & B. Building Waynesboro, Virginia 22980 540 -942 -1161 • FAX: 540 -942 -1163 • E -MAIL: jma(abruchcum.com Preliminary Detention Calculations t u❑ L B. & B. Building, Waynesboro Virginia 22980 -L 540 - 942 -1161 FAX: 540-942-1163 E-MAIL jma(ubrucheum.coin l_- __ -Jolu McNair and AccnciatPS_ -]/ I Consulting Engineers Detention: Detention for this site was analyzed as follows. All off -site runoff from the Northeast and Northwest is bypasses the site via existing concrete curbing on the adjoining parcel and along Westfield Road. All off -site runoff to the Southeast and Southwest is down slope from the site and do not contribute any runoff to the site. Requirements for stormwater quantity and quality are met using a network of 4 — 24" 0 underground storage pipes and a Filterra® Stormwater Bioretention Filtration System. The stormwater runoff that will be going through the biofilters and the underground storm water storage pipes includes all of the on -site impervious areas and the majority of the on -site pervious areas. am Johi"rNair- uul.Associates Cuu.cultiu,� E gmeers L. B. & B. Building, Wayncsburo. Virginia 22980 540- 942 -1101 • tAX:540- 942 -1103 • E -MAIL: jma!uhruchcum. cum Pre - Developed Conditions t� John � dates Consulting Enginecrc Pre - Developed Conditions: Area = 0.548 Acres L. B. & B. Building, Waynesboro, Virginia 22980 540 -942 -1161 • FAX: 540-942-1163 • E -MAIL: jimila brucheum.com C = 0.30 (Unimproved Area w /steep slopes) T = Overland Flow (T + Shallow Concentrated Flow (T Tc1 = 100' Overland Flow (grass) average slope = (455.7- 452.8)/100 = 0.029 = 2.9% Tc1 = 12.8 min. (from the Seelye chart - Plate 5 -1 VAESC Handbook) TC2 = 108' Shallow Concentrated Flow (unpaved) average slope = (452.8- 439.6)/108 = 0.122 = 12.2% Using Plate 5 -2 VAESC Handbook Velocity = 5.7 fps T _ (108/5.7) x (1 /60) = 0.32 min. Tc = TC1 + T = 12.8 + 0.32 = 13.12 min. Q2 = C i A = (0.3)(3.68 in/hr)(0.548) = 0.61 02 = 0.61 cfs Q10 = C i A = (0.3)(4.84 in/hr)(0.548) = 0.79 Qio = 0.79 cfs Q1oo = C i A = (0.3)(6.34 in/hr)(0.548) = 1.04 Q190 = 1.04 cfs LEGEND DRAINAGE BOUNDARY Tc PATH 1 1 l \r � �I -� (ARE/ I ? � I ! I { I 3 N47 °30'21 "E 199.90 = 0.548 ACRES ,4°30'21"W 200.00 PRE DEVELOPED CONDITION SCALE: 1 " =20' !ll � l j c -� m vD Im John McNair.aullllssociatcs C on.cultmg Engmecrc L B & B Building, Wayncsboro, Virginia 22 980 540-942-1161 • FAX: 540-942-1163 • E -MAIL: imam bruchcum.ann Post - Developed Conditions John McNair and Assnciates_ -- Consulting Engineers Post - Developed Condition: Area = 0.548 L. B. & B. Building, Waynesboro, Virginia 22980 540-942-1161 • FAX: 540-942-1163 • E -MAIL: jma!a bruchcum.com T, = 5 min. (assumed based on site imperviousness and slopes) Impervious area = 0.38 Acres Grass area = 0.17 Acres C = [0.38(0.9) + 0.17(0.4)] / 0.548 = (0.342 +0.068)/0.548 = 0.75 C = 0.75 Detention: An underground detention area (storage pipe) was sized using the Rational Method. Post- Developed flows for both the 2 -year and 10 -year storms were limited to the Pre - Developed flow rates. Q = C i A = (0.75)(5.18 in/hr)(0.548) = 2.13 Q = 2.13 cfs Q = C i A = (0.75)(6.67 in/hr)(0.548) = 2.74 Q = 2.74 cfs Q10o = C i A = (0.75)(8.76 in/hr)(0.548) = 3.60 Q 1 p0 = 3.60 cfs LEGEND .�. .� DRAINAGE BOUNDARY Tc PATH .,-cl �T Na O o� N N co �J i BIOFILTER #2 -F= e N47 °30'21 "E 199.90 BIOFILTER #1 f I I r i t f r r l I f { ,4°30'21 "W 200.00 POST DEVELOPED CONDITION SCALE: 1 " =20' F s r r � i l F s a JoluzMclYair audAssociates Consulting Engineers Outlet Structure: L. B. & B. Building, Wavncshoro V irginia 22 9,1) 540-942-1101 • FAX: 540-942-1163 • E -MAIL: jma(a brucheum.com Hydroflow was used to help size the outlet structure. Hydroflow was also used to create Stage /storage and stage /discharge graphs. The outlet structure consists of an 18" Riser (weir) with a 5"0 low -flow orifice and an 18'" outlet barrel. The 5"0 low -flow orifice was set at Elev. = 440.00 The top of the 18 Riser is set at Elev. = 442.00, which will also serve as the emergency overflow. See Stormwater Outlet Structure detail on sheet C- Hydrograph Summary Report Hyd. No. Hydrograph type (origin) Peak flow (cfs) Time interval (min) Time to peak (min) Volume (cuft) Inflow hyd(s) Maximum elevation (ft) Maximum storage (cult) Hydrograph description 1 Rational 2.13 1 5 846 - - -- - - - - -- - - - - -- POST 2 Reservoir 0.63 1 11 830 1 441.26 512 ROUTED FLOW 3 Rational 0.61 1 13 626 - - -- - - - - -- - - - - -- PRE 205186 - detention.gpw Return Period: 2 Year Tuesday, Oct 25 2005, 11:23 AM Hydraflow Hydrographs by Intelisolve Hydrograph Plot Hydraflow Hydrographs by Intelisolve Tuesday, Oct 25 2005, 11:23 AM Hyd. No. 2 ROUTED FLOW Hydrograph type = Reservoir Peak discharge = 0.63 cfs Storm frequency = 2 yrs Time interval = 1 min Inflow hyd. No. = 1 Max. Elevation = 441.26 ft Reservoir name = Detention -1 Max. Storage = 512 cuft Storage Indication method used. Q (cfs) 3.00 2.00 1.00 - 1 11 1 1, Hydrograph Volume = 830 cult ROUTED FLOW Hyd. No. 2 -- 2 Yr Q (cfs) 3.00 0.1 0.2 0.3 Hyd No. 2 Hyd No. 1 0.3 0.4 0.5 0.6 i I - 2.00 1.00 0.00 0.7 Time (hrs) Hydrograph Plot Hydraflow Hydrographs by Intelisolve Friday, Oct 21 2005, 1:22 PM Hyd. No. 3 PRE Hydrograph type = Rational Peak discharge = 0.61 cfs Storm frequency = 2 yrs Time interval = 1 min Drainage area = 0.548 ac Runoff coeff. = 0.3 Intensity = 3.682 in/hr Tc by User = 13.00 min I DF Curve = Albemarle-IDF-HDA-05-03.IDF Asc/Rec limb fact = 1/1.65 Hydrograph Volume = 626 cult Q (Cfs) 1.00 0.90 0.80 0.70 0.60 0.50 0.40 0.30 0.20 0.10 A rn) n PRE Hyd. No. 3 -- 2 Yr Q (Cfs) 1.00 0.90 0.80 0.70 0.60 0.50 0.40 0.30 0.20 0.10 0 5 10 — Hyd No. 3 0.00 15 20 25 30 35 Time (min) L 0 5 10 — Hyd No. 3 0.00 15 20 25 30 35 Time (min) Hydrograph Plot Hydraflow Hydrographs by Intelisolve Hyd. No. 1 POST Hydrograph type = Rational Storm frequency = 2 yrs Drainage area = 0.548 ac Intensity = 5.180 in /hr IDF Curve = Albemarle - IDF- HDA- 05- 03.IDF Friday, Oct 21 2005, 1:27 PM Peak discharge = 2.13 cfs Time interval = 1 min Runoff coeff. = 0.75 Tc by User = 5.00 min Asc /Rec limb fact = 1/1.65 Hydrograph Volume = 846 cuft Q (cfs) Cwt 2.00 1.00 1 11 w Hyd No. 1 5 POST Hyd. No. 1 -- 2 Yr 10 Q (cfs) 3.00 2.00 1.00 0.00 15 Time (min) Hydrograph Plot Hydraflow Hydrographs by Intelisolve Hyd. No. 2 ROUTED FLOW Hydrograph type = Reservoir Storm frequency = 2 yrs Inflow hyd. No. = 1 Reservoir name = Detention -1 Monday, Oct 24 2005, 4:47 PM Peak discharge = 0.63 cfs Time interval = 1 min Max. Elevation = 441.26 ft Max. Storage = 512 cuft Storage Indication method used. Q (cfs) 3.00 2.00 1.00 0.00 0 5 Hyd No. 2 ROUTED FLOW Hyd. No. 2 -- 2 Yr 10 15 20 25 30 Hyd No. 1 Req. Stor = 512 cuft Hydrograph Volume = 830 cuft Q (cfs) 3.00 2.00 35 r 1.00 V III 0.00 40 Time (min) Hydrograph Summary Report Hyd. No. Hydrograph type (origin) Peak flow (cfs) Time interval (min) Time to peak (min) Volume (cuft) Inflow hyd(s) Maximum elevation (ft) Maximum storage (cuft) Hydrograph description 1 Rational 2.74 1 5 1,089 - - -- - - - -- - - - - -- POST 2 Reservoir 0.73 1 11 1,068 1 441.59 703 ROUTED FLOW 3 Rational 0.79 1 13 822 - - -- - - - - -- - - - - -- PRE i I i 205186 - detention.gpw Return Period: 10 Year Tuesday, Oct 25 2005, 11:23 AM Hydraflow Hydrographs by Intelisolve Hydrograph Plot Hydraflow Hydrographs by Intelisolve Tuesday, Oct 25 2005, 11:23 AM Hyd. No. 2 ROUTED FLOW Hydrograph type = Reservoir Peak discharge = 0.73 cfs Storm frequency = 10 yrs Time interval = 1 min Inflow hyd. No. = 1 Max. Elevation = 441.59 ft Reservoir name = Detention -1 Max. Storage = 703 cuft Storage Indication method used. Hydrograph Volume = 1,068 cuft ROUTED FLOW Q cfs Q (cfs) ( ) Hyd. No. 2 -- 10 Yr - 3.00 2.00 1.00 1 11 1 1, 0.1 0.2 0.3 Hyd No. 2 Hyd No. 1 0.3 0.4 0.5 0.6 2.00 1.00 0.00 0.7 Time (hrs) Hydrograph Plot Hydraflow Hydrographs by Intelisolve Friday, Oct 21 2005, 1:22 PM Hyd. No. 3 PRE Hydrograph type = Rational Peak discharge = 0.79 cfs Storm frequency = 10 yrs Time interval = 1 min Drainage area = 0.548 ac Runoff coeff. = 0.3 Intensity = 4.837 in /hr Tc by User = 13.00 min OF Curve = Albemarle - IDF- HDA- 05- 03.IDF Asc /Rec limb fact = 1/1.65 Hydrograph Volume = 822 cuft Q (cfs) 1.00 0.90 0.80 0.70 0.60 0.50 0.40 0.30 0.20 0.10 0.00 0 PRE Hyd. No. 3 -- 10 Yr Q (cfs) — 1.00 0.90 0.80 0.70 0.60 0.50 0.40 0.30 0.20 0.10 0.00 35 Time (min) 5 10 15 20 25 30 Hyd No. 3 Hydrograph Plot Hydraflow Hydrographs by Intelisolve Hyd. No. 1 POST Hydrograph type = Rational Storm frequency = 10 yrs Drainage area = 0.548 ac Intensity = 6.666 in /hr IDF Curve = Albemarle - IDF- HDA- 05- 03.IDF Friday, Oct 21 2005,1:24 PM Peak discharge = 2.74 cfs Time interval = 1 min Runoff coeff. = 0.75 Tc by User = 5.00 min Asc /Rec limb fact = 1/1.65 Hydrograph Volume = 1,089 cult Q (cfs) i 11 r 11 1.00 - 1 11 1 5 POST Hyd. No. 1 -- 10 Yr 10 Q (cfs) 11 2.00 1.00 0.00 15 Time (min) Hyd No. 1 Hydrograph Plot Hydraflow Hydrographs by Intelisolve Hyd. No. 2 Time interval ROUTED FLOW Max. Elevation Hydrograph type = Reservoir Storm frequency = 10 yrs Inflow hyd. No. = 1 Reservoir name = Detention -1 Monday, Oct 24 2005, 4:48 PM Peak discharge = 0.73 cfs Time interval = 1 min Max. Elevation = 441.59 ft Max. Storage = 703 cuft Storage Indication method used. Q (cfs) 3.00 2.00 - 1.00 - 0.00 0 5 10 15 Hyd No. 2 Hyd No. 1 Hydrograph Volume = 1,068 cuft ROUTED FLOW Hyd. No. 2 -- 10 Yr 20 25 30 35 Req. Stor = 703 cuft Q (cfs) 3.00 - 2.00 - 1.00 0.00 40 Time (min) Hydrograph Summary Report Hyd. No. Hydrograph type (origin) Peak flow (cfs) Time interval (min) Time to peak (min) Volume (cuft) Inflow hyd(s) Maximum elevation (ft) Maximum storage (cuft) Hydrograph description 1 Rational 3.60 1 5 1,431 - - -- - - - -- - - - - -- POST 2 Reservoir 1.53 1 10 1,404 1 442.13 928 ROUTED FLOW 3 Rational 1.04 1 13 1,077 - - -- - - - - -- - - - - -- PRE 205186 - detention.gpw Return Period: 100 Year Tuesday, Oct 25 2005, 11:23 AM Hydraflow Hydrographs by Intelisolve Hydrograph Plot Hydraflow Hydrographs by Intelisolve Hyd. No. 2 ROUTED FLOW Hydrograph type = Reservoir Storm frequency = 100 yrs Inflow hyd. No. = 1 Reservoir name = Detention -1 Tuesday, Oct 25 2005, 11:23 AM Peak discharge = 1.53 cfs Time interval = 1 min Max. Elevation = 442.13 ft Max. Storage = 928 cuft Storage Indication method used. ROUTED FLOW Q (cfs) Hyd. No. 2 -- 100 Yr 4.00 - - 3.00 2.00 1.00 1 11 $ 1 Hydrograph Volume = 1,404 cuft Q (cfs) 1 4.00 0.1 0.2 0.3 0.3 0.4 0.5 0.6 0.7 Hyd No. 2 Hyd No. 1 3.00 2.00 1.00 0.00 0.8 Time (hrs) Hydrograph Plot Hydraflow Hydrographs by Intelisolve Hyd. No. 3 PRE Hydrograph type = Rational Storm frequency = 100 yrs Drainage area = 0.548 ac Intensity = 6.342 in /hr IDF Curve = Albemarle - IDF- HDA- 05- 03.IDF Friday, Oct 21 2005,1:23 PM Peak discharge = 1.04 cfs Time interval = 1 min Runoff coeff. = 0.3 Tc by User = 13.00 min Asc /Rec limb fact = 1/1.65 Hydrograph Volume = 1,077 cult Q (cfs) 2.00 1.00 5 10 Hyd No. 3 PRE Hyd. No. 3 -- 100 Yr 15 20 25 30 Q (cfs) 2.00 - 1.00 0.00 35 Time (min) Hydrograph Plot Hydraflow Hydrographs by Intelisolve Hyd. No. 1 POST Hydrograph type = Rational Storm frequency = 100 yrs Drainage area = 0.548 ac Intensity = 8.762 in /hr IDF Curve = Albemarle - IDF- HDA- 05- 03.IDF Friday, Oct 21 2005, 1:23 PM Peak discharge = 3.60 cfs Time interval = 1 min Runoff coeff. = 0.75 Tc by User = 5.00 min Asc /Rec limb fact = 1/1.65 Hydrograph Volume = 1,431 cuft Q (cfs) 4.00 3.00 2.00 1.00 WE N Hyd No. 1 5 POST Hyd. No. 1 -- 100 Yr 10 Q (cfs) 4.00 3.00 2.00 1.00 0.00 15 Time (min) Hydrograph Plot Hydraflow Hydrographs by Intelisolve Hyd. No. 2 ROUTED FLOW Hydrograph type = Reservoir Storm frequency = 100 yrs Inflow hyd. No. = 1 Reservoir name = Detention -1 Monday, Oct 24 2005, 4:48 PM Peak discharge = 1.53 cfs Time interval = 1 min Max. Elevation = 442.13 ft Max. Storage = 928 cuft Storage Indication method used. Q (cfs) 4.00 3.00 N W 1.00 0.00 0 ROUTED FLOW Hyd. No. 2 -- 100 Yr 5 10 15 20 25 30 35 Hyd No. 2 Hyd No. 1 Req. Stor = 928 cuft Hydrograph Volume = 1,404 cuft 40 Q (cfs) - 4.00 3.00 2.00 1.00 0.00 45 Time (min) Top of underground ctorage. El". 442.10 3.00 4 barrels @ 2.00 ft di:)., 0.25% clope 2.00 1.00 0.00 Fro nt Vi ew NTS - Looking upotre:�m 18.0 LF of 18.0 in Cu l YA - InV. 440.1 (100 yr) (10 yr) (2 yr) Schematic only. Not for construction. Detention -1 4.70 ft Ri:er W e1rA - Elcv. 442.00 1.00 I Hydraflow Hydrographs Pond Draw I Project: 205186 - detention.gpw I Monday, Oct 24 2005, 4:49 PM I p -i d b e t5.�0 u as 2.0 ft Ilia @ 0.25% slaps a dutltt ,r•rv��• o0o YO plan V, VATS Schematic only Not for const Monday, Oct 24 2 005, 4'.49 QM project: 20518 de tention.gp`N � RraW 2 STORMWATER OUTLET STRUCTURE SCALE WT TO SCALE lg d 'A I MANHOLE I OPENING ABOVE / 24" HDPE FROM UNDERGROUND / 18" HDPE BARREL STORAGE AREA �- i @1 00 K 13" END CAI' W S' OKIFICE INV -44000 a N -12 PKOLINK W I MANIFOLD .e C I EE IS I KA P DOWN IO .. t101 OF S IRUCIUKE 10 64 A PKEVf_NI FLOAIING) p A 24" HDPE FROM UNDERGROUND P LAN STORAGE AREA N.T.S. V1)0 1 S I ANDAKD PKECAS 1 MANHOLE IOP -FLAI SLAB Z - WIDE IOPUNII MANHOLE OPENING ION ELEV = 144.10 a ld A z_� C N $O V LLFV- 34'_00 d ZZZ : + \� F FROM UNDERGROUND FROM UNDERGROUND J1 STORAGE PIPES STORAGE PIPES 1 \' 18" END CAP ` INV - 440 10 � 7 WHORE BARREL INV = x-1010 \,\ I^ OK 34 l ' Q 7 C Q ON1F0l.0 IIF[- P ROFILE IS KAP DOWN BOI "IOM OF SI KUCIUKE 10 N.T.S. PKLVFN I FLOA I ING) 2 STORMWATER OUTLET STRUCTURE SCALE WT TO SCALE Erosion and Sediment Control Plan Narrative for Westfield Road Center Albemarle County, Virginia Prepared by John McNair & Associates Consulting Engineers Waynesboro, Virginia April 24, 2006 Project Description: Westfield Road Center is an Office Infill site. Area disturbed is 0.55 ac.; total site area is 0.55 ac. Existing Site Conditions: The site is presently vacant. It has been previously graded. There are 30+ year old trees on the site that will be saved, in addition to brushy and tree covered areas that will be cleared and regraded for building and parking lot construction. Adjacent Property: The site is bounded on the East by FMW Partnership, a medical office, on the South by Modab, LLC, a warehouse, on the West side by Albemarle First Bank, and on the North by Westfield Road. Off -Site Areas: Site work will require export of cut material, which will be transported from this site to a site with an approved erosion and sediment control plan. The owner or contractor will provide the location of the waste site for the extra material. Critical Erosion Area: The Albemarle First Bank collects storm water and releases it to the southwest corner of this site to an existing drainswale which crosses to the southeast corner of this site. This collected water then enters an existing open ended culvert on the Modab, LLC property. The existing storm water from this site drains to this Swale and releases to the same point. We are providing a temporary sediment trap on the adjoining Modab property prior to stormwater entering the existing, off -site storm system. Soils: This site is in Elioak loam soils based on the Soil Survey Map #11 of Albemarle County. It is listed as deep, gently sloping, and well drained. The hazard of erosion is moderate for these soils. As mentioned earlier, this site has been previously graded and may contain additional soil types. Erosion and Sediment Control Measures: Unless otherwise indicated, all vegetative and structural erosion and sediment control measures shall be constructed and maintained according to the minimum standards and specifications of the Virginia Erosion And Sediment Control Handbook (VESCH). The minimum standards of the VESCH shall be adhered to unless waived or approved by a variance. Changing site conditions may require adjustment, relocation, or installation of additional measures. The Albemarle County Engineer may require modifications as necessary. Page ] of 5 Structural Practices: Construction Entrance: (CE) 3.02 The construction entrance will be located off of Westfield Road at the Northeast corner of the site. Minimum area of the construction entrance will be 24 feet x 70 feet as shown on the Erosion & Sediment Control Plan details. During periods of rain, when vehicles have mud on their wheels or tracks, drivers shall be required to remove mud by brushing, washing, or other means. All soil tracked onto the existing roadway will be removed every four (4) hours or as required by the conditions or the Inspector. Silt Fence: (SF) 3.05 Silt fence shall be constructed as indicated. The silt fence will be installed as detailed, and will be checked on a daily basis. The silt fence shall filter sediment -laden runoff before leaving the site. Construction Road Stabilization: (CRS) 3.03. Temporary stabilization with stone of access roads or parking areas immediately after reaching subgrade to reduce erosion and prevent regrading before final surfacing of site. Inlet Protection_ (IP) 3.07. Sediment filter to be provided around storm drain inlets to prevent sediment from entering the storm drain system. Outlet Protection_ (OP) 3.18. Installation of riprap section as a Stilling Basin below storm drain outlet to reduce erosion and undercutting from scour and to reduce velocities before stormwater enters receiving channel. RipRap_ (RR) 3.19. Permanent, erosion resistant ground cover of large, loose, angular stone installed where soil condition, water turbulence and velocity are such that soil may erode under design conditions. Dust Control_ (DC) 3.59 Dust Control shall be used as needed in order to prevent visible airborne dust transgressing to neighboring property, to prevent surface and air movement of dust from exposed soil surfaces and to reduce the presence of airborne substances which may be harmful or injurious to human health, welfare, or safety, or to animals or plants. Temporary Sediment Trap: (ST) — 3.13 — Sediment trap to be provided near southeast corner of the site on adjacent property to prevent sediment from entering the downstream storm system. Tree Preservation and Protection_ (TP) 3.39. Protecting existing trees from mechanical and other injury during land disturbing and construction activity. Page 2 of 5 Vegetative Practices: In general, all areas that are not impervious, will be landscaped, therefore, we are recommending mulch as temporary stabilization. In the event that construction is delayed, temporary and permanent seeding instructions and materials are included as follows: Temporary Seeding: (TS) - 3.31- All areas to be rough - graded during the initial phase of construction and the topsoil stockpiles shall be seeded with fast germinating, temporary vegetation immediately following grading, within 7 days. All non - paved, denuded areas which will be left dormant for extended periods shall be seeded as specified on the plan. See seeding specification for types. Seed and associated mixes shall be applied following the grading operation. Seed: Selection of the appropriate seed mixture will depend upon the time of the year it is to be applied (Table 3.31 -B): Sept. 1 - Feb. 15: use a 50150 mix of Cereal (Winter) Rye (Secale cereale) and Annual Ryegrass (Lolium multiflorum), at 50 to 100 lb. per acre.; Feb. 16 - April 30: use Annual Ryegrass (Lolium Multi - Florum) at the rate of 60 to 100 lb. per acre. May 1 - Aug. 31: use German Millet (Setaria italica) at 50 lb. per acre. Seedbed Preparation shall include: Lime: applied at 2 tons per acre, uniformly to the surface and incorporated into the top 2 -4 inches of soil as recommended in Table 3.31 -C or, based upon soil pH, as recommended in Table 3.31 -A. Fertilizer: applied at 600 lb. per acre of 10 -20 -10 or equivalent and incorporated into the top 2 -4 inches of soil. Surface Roughening: Surface shall be loosened by discing, raking, harrowing, or other acceptable means. Roughening won't be required if the area has been recently loosened. Mulching: is required in fall for winter cover and at other times of the year when areas are on slopes in excess of 4:1, or adverse soil conditions or excessively dry or hot weather. Hay or straw mulch should come from wheat or oats and may be spread by hand or machine. Straw can be windblown and must be anchored down by an acceptable method, see Std. & Spec. 3.35. Mulch: (MU) 3.35: Wood mulch is to be used to cover exposed topsoil areas while waiting for landscaping. In the event that construction is delayed and the site is stabilized with grass seeding, straw or hay mulch shall be spread at the rate of 1.5 to 2 tons per acre (minimum 2 tons per acre for winter cover). Mulch shall be free from weeds and course matter, must be anchored, and may be hand or machine spread. Mulch shall be applied as soon as possible after seeding. In no case shall mulching be delayed more than 48 hours. Page 3 of 5 Permanent Stabilization: (PS) 3.32: All areas disturbed by construction will be stabilized by establishing a good stand of grass or other landscaping in all areas not covered by building or pavement. All disturbed areas shall be fertilized, seeded, and mulched within 7 days after the completion of grading, according to the following: Lime 3.32: Amount to be determined by Soil Test and in accordance with Table 3.32 -F, or 2 tons per acre of pulverized agricultural limestone, uniformly applied to surface to be seeded during seedbed preparation and incorporated into the top 4 -6 inches of soil. Fertilizer 3.32: 1000 pounds per acre of 5 -20 -10 or equivalent, uniformly applied to the surface to be seeded during seedbed preparation and incorporated into the top 4 -6 inches of soil. Seed 3.32: One hundred eight (108) pounds per acre of Tall Fescue variety KY -31, 2 pounds per acre of Red Top Grass, 20 pounds per acre of Seasonal Nurse Crop, and 20 pounds per acre of Crown vetch. Seasonal Nurse Crop shall be as follows: Feb. 16 through April use Annual Rye; May 1 through Aug. 15 use Foxtail Millet; Aug. 16 through October use Annual Rye, November through February 15 use Winter Rye. Seed shall be of the latest seed crop available and shall have been tested within six months of the date of seeding and meet the requirements of the Virginia Field Seed Law Maintenance: In general, all erosion and sediment control measures will be checked daily, any off -site tracking of soils must be cleaned up every four (4) hours and after each significant rainfall; the objective is there will be no tracking or spillage in city streets or on neighboring properties. All sediment removed during maintenance shall be blended with topsoil, seeded, and stabilized, buried in an approved location, or handled in another method approved by the County of Albemarle. The seeded areas shall be checked regularly to ensure that a good stand is maintained. Areas should be fertilized and re- seeded as needed. Stormwater Runoff Considerations: Construction operations should be sequenced so that grading operations can begin and end as quickly as possible. The job superintendent shall be responsible for the installation and maintenance of all erosion and sediment measures. The sediment trap will be located below the site. Silt fence and inlet protection at the lower end of the site may be removed after the site has been stabilized. The entire site must be stabilized prior to final implementation of the Filterra bio- filters. Stormwater Detention Stormwater detention will not be required based on Albemarle County Ordinance: 17-314-F-4 Page 4 of 5 The applicable Minimum Standards are copied from the Virginia Erosion and Sediment Control Handbook: Minimum Standards 4(1): Permanent or temporary soil stabilization must be applied to denuded areas within 7 days after final grade is reached on anv portion of the site. Temporary soil stabilization shall be applied within 7 days to denuded areas which may not be at final grade but will remain dormant (undisturbed) for longer than 30 days. Permanent stabilization shall be applied to areas that are to be left dormant for more than one year. Soil stabilization refers to measures which protect soil from the erosive forces of raindrop impact and flowing water. Applicable practices include vegetative establishment, mulching and the early application ofgravel base on areas to be paved. Soil stabilization measures should be selected to be appropriate for the time of year, site conditions and estimated duration of use. Minimum Standards 4(2): During construction of the project, soil stock piles shall be stabilized or protected with sediment trapping measures. The applicant is responsible for the temporary protection and permanent stabilization of all soil stockpiles on site as well as soil intentionally transported from the project area. Minimum Standards 4(3): A permanent vegetative cover shall be established on denuded areas not otherwise permanently stabilized. Permanent vegetation shall not be considered established until a ground cover is achieved that, in the opinion of the local program administrator or his designated agent, is uniform, mature enough to survive and will inhibit erosion. Minimum Standards 4(4): Sediment basins and traps, perimeter dikes, sediment barriers and other measures intended to trap sediment shall be constructed as a first step in any land disturbing activity and shall be made functional before up slope land disturbance takes place. Minimum Standards 4(5): Stabilization measures shall be applied to earthen structures such as dams, dikes, and diversions immediately after installation. Minimum Standards 4(7): Cut and fill slopes shall be designed and constructed in a manner that will minimize erosion. Slopes that are found to be eroding excessively within one year of permanent stabilization shall be provided with additional slope stabilizing measures until the problem is corrected. Minimum Standards 4(17): Where construction vehicle access routes intersect paved public roads, provisions shall be made to minimize the transport of sediment by vehicular tracking onto the paved surface. Where sediment is transported onto a public road surface, the road shall be cleaned thoroughly at least every four hours. Sediment shall be removed from the roads by shoveling or sweeping and transported to a sediment control disposal area. Street washing shall be allowed only after sediment is removed in this manner. This provision shall apply to individual subdivision lots as well as to larger land - disturbing activities. Minimum Standards 4(18): All temporary erosion and sediment control measures shall be removed within 30 days after final site stabilization or after the temporary measures are no longer needed, unless otherwise authorized by the local program administrator. The disturbed soil areas resulting from the disposition of temporary measures shall be permanently stabilized to prevent further erosion and sedimentation. Page 5 of 5 I JoAnMcNair audAssnc Wes _ - - -' I Consulting Engineer i L. B. & B. Building, Waynesboro, Virp_inia 22980 540 -942 -1161 • FAX: 540 -942 -1163 • E -MAIL: jma(abrucheum.com DETENTION of STORM DRAIN CALCULATIONS for Westfield 10 -25 -05 David L. Collins, P.E., L.S. f , I a - - -_- - -- — - - -- __— ohn M _ _ --- ciate. II � Consulting Engineers Stormwater Treatment: L. B. & B. Building, Waynesboro Virginia 22980 540- 942 -1161 • FAX:540- 942 -1163 • E- MAIL:jmaLbrucheum.com Based on the Albemarle County Ordinance: 17- 314 -F -4 it was determined that the site is exempt from stormwater detention. Requirements for stormwater quality are met using Filterra® Stormwater Bioretention Filtration System. The stormwater runoff that will be going through the biofilters will then be discharged from the site at structure A -5. All off -site runoff from the Northeast bypasses the site via existing concrete curbing on the adjoining parcel and along Westfield Road. All off -site runoff from the Northwest drains onto the site and is collected in structure A -6 to allow it to pass through the site. All off -site runoff to the Southeast and Southwest is down slope from the site and do not contribute any runoff to the site. David L. Collins, P.E., L.S. John McNair & Assoc. 109 South Wayne Avenue Waynesboro, Virginia 22980 (540) 942 -1 16 1 (540) - 942 - 1163 FAX November 22, 2005 Plan Review of Filterra Westfield Project, Albemarle County Dear Sirs Thank you for submitting the partial plans for our review of the Westfield project. Filterra structures A3(8'x4') and A4(6'x6') were studied for; • Planned Filterra® box size • Filterra® contributing drainage area meeting project's regional sizing specification • Spot elevations (TC) for Filterra® and bypass relief • Filterra® invert elevations are 3.5' below TC • The bypass is lower than the Filterra® elevation (spot elevations) • The grading pattern encourages cross linear flow and not head -on flow • The Filterra® outlet drain pipe is sized correctly and exits perpendicular to the wall • For any conflicting structures such as storm drain pipes below Filterra® • For most efficient placement of Filterra® units • 4 -6" opening throat detail and standard notes on plans The plan review concluded that the Filterra structures listed above were sited and sized appropriately to treat stormwater to our published specifications. Operational consistency with these specifications is contingent upon the stormwater units being installed correctly and according to the plans, as well as regular maintenance being performed. Installation Help documents will be forwarded to the Buyer at time of order. The Filterra`' Installation, Operation and Maintenance Manual will be forwarded to the Owner when the units are activated by Americast. Yours sincerely Dean Baddorf Filterra® Stormwater Bioretention Filtration System Manufactured by Americast T: (804) 798 -6068 MER /�/� =�J�� 1 1352 Virginia Precast Road F: (804) 752 -6838 - Ashland, VA 23005 E: designCfilterra.com www.filterra.com l ❑ _ Joh Mr Nair and Acca les- i j Consulting Engineers L. B. & B. Building, Waynesboro, Virginia 22980 540-942-1101 • FAX: 540-942-1163 • E -MAIL: jmaw bruchcum.com Pre - Developed Conditions r aa /u Consulting Engineers J Pre - Developed Conditions: Area = 0.548 Acres L B & B Building, Waynesboro Virginia 229210 540-942-1161 • FAX: 540-942-1163 • E -MAIL: jma(60rucheum.com C = 0.30 ( Unimproved Area w /steep slopes) T = Overland Flow (T + Shallow Concentrated Flow (T TC = 100' Overland Flow (grass) average slope = (455.7 - 452.8)/100 = 0.029 = 2.9% T = 12.8 min. (from the Seelye chart - Plate 5 -1 VAESC Handbook) TC2 = 108' Shallow Concentrated Flow (unpaved) average slope = (452.8- 439.6)/108 = 0.122 = 12.2% Using Plate 5 -2 VAESC Handbook Velocity = 5.7 fps TC2 _ (108/5.7) x (1 /60) = 0.32 min. T = TC, + T = 12.8 + 0.32 = 13.12 min. Q = C i A = (0.3)(3.68 in/hr)(0.548) = 0.61 Q = 0.61 cfs Q10 = C i A = (0.3)(4.84 in/hr)(0.548) = 0.79 Q, = 0.79 cfs Q „ = C i A = (0.3)(6.34 in/hr)(0.548) = 1.04 Qloo = 1.04 cfs II- Johl McNair and Ass ciates i Consulting Enginecrs L. B. &, B. Building, Waynesboro, Virginia 22980 540- 942 -1161 • FAX: 540-942-1163 • E -MAIL: jma(a Post - Developed Conditions I / I ,l - Joh McNair an d Assnciate._j ' Consniting Engineers Post - Developed Condition: Area = 0.548 L. B. & B. Building, Waynesboro, Virginia 22980 540- 942 -1161 • FAX: 540 -942 -1163 • F- MAIL:jma(a- bruchcum.com T, = 5 min. (assumed based on site imperviousness and slopes) Impervious area = 0.38 Acres Grass area = 0.17 Acres C = [0.38(0.9) + 0.17(0.4)] / 0.548 = (0.342 +0.068)/0.548 = 0.75 C = 0.75 Detention: An underground detention area (storage pipe) was sized using the Rational Method. Post- Developed flows for both the 2 -year and 10 -year storms were limited to the Pre - Developed flow rates. Q = C i A = (0.75)(5.18 in/hr)(0.548) = 2.13 Q2 = 2.13 cfs Q10 = C i A = (0.75)(6.67 in/hr)(0.548) = 2.74 O i n = 2.74 cfs Q = C i A = (0.75)(8.76 in/hr)(0.548) = 3.60 Qroo = 3.60 cfs i ,_Joh MrNn; raudAssociates Consulting Engineers � L B & B. Building Waynesboro, Virginia 22980 540 -942 -1161 • FAX: 540 -942 -1163 • F -MAIL: jrna(,tbruchcum.com Miscellaneous Calculations --- Jw--- John McNair and Asso c i ates L P 3 V,19,— 22560 Designed By IyV Checked By Date Date / U -- Project Project No. ZC Sheet of i V, 1- C' 44 it `F� f t) n = ©. ©15 0 0 1.67 qC-7 - v , b C5 T I VI C t " I L. , I --) r r -p- cA ( � ) = ( Z- ) ( 2-;7 — s . —� � Chapter 9 — Storm Drains Appendix 9C -7 Flow in Composite Gutter Sections Source: HEC No. 12, FHWA t� N 1 of 1 VDOT Drainage Manual 9 f 9 �r 0 -- -- --- - -- r 2O ° f W o ° o ° o '* 1 1 N m O Y M N Op O 0 0 O O O O O O O 0 0 O O O O O O O U0 o N , h � M H m b 4 f' W - O O 31, N 3 i z M/1 Source: HEC No. 12, FHWA t� N 1 of 1 VDOT Drainage Manual ✓ Designed By Checked By Date I & Date John - McNair and Associates C e ( L + , Project i� Project No. ?L Sheet of L t i, i V\/ I � -,-� L -fir � ( � -�a� 2 � L�r•`t� (� \ '_ Q , � (,� o e,� -7-7 I- -, d­? C f-f 't- r C5 C, A = ��- 5 ���,�7�(� �-z � _ x.41 L +V eA V\- L t i, i V\/ I � -,-� L -fir � ( � -�a� 2 � L�r•`t� (� \ '_ Q , � (,� o e,� -7-7 100 Yr Flow Worksheet for Circular Channel Input Data Mannings Coefficient 0.013 Channel Slope 0.002500 ft/ft Diameter 24.00 in Discharge 10.24 cfs Results _Project Description Depth Project File c: \haestad \academic \fmw \project2.fm2 Worksheet WESTFIELD Flow Element Circular Channel Method Manning's Formula Solve For Channel Depth Input Data Mannings Coefficient 0.013 Channel Slope 0.002500 ft/ft Diameter 24.00 in Discharge 10.24 cfs Results Depth 1.49 ft Flow Area 2.51 ft 2 Wetted Perimeter 4.17 ft Top Width 1.74 ft Critical Depth 1.15 ft Percent Full 74.54 Critical Slope 0.005242 ft/ft Velocity 4.08 ft/s Velocity Head 0.26 ft Specific Energy 1.75 ft Froude Number 0.60 Maximum Discharge 12.17 cfs Full Flow Capacity 11.31 cfs Full Flow Slope 0.002049 ft/ft Flow is subcritical. 11/22/05 FlowMaster v5.17 04:05:50 PM Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 (203) 755 -1666 Page 1 of 1 1992 3.18 JaOj `OILS dL),AdLd 09 p CD CD CD GI C) - 0 Q CD co C) LLJ LLJ 7 + -- ag — gggg7q� JaOj `OILS dL),AdLd 09 p CD CD CD Source: USDA-SCS 111- 164 Plate 3.18-3 GI 0 Q CD C) LLJ LLJ C, C iT o v v C. 3: s- 4J 7= CD CD Source: USDA-SCS 111- 164 Plate 3.18-3 CD C) LLJ LLJ C, C iT o v v C. 3: s- 4J 7= CD CD Uj O fu Z= N C:. C) 0- 0 t 0 C3 `� ~ 3 O O O U- F-- 41 41 0' .+, E 41 CL Ln 0 Source: USDA-SCS 111- 164 Plate 3.18-3 Short Version BMP Computations For Worksheets 2 - 6 Albemarle County Water Protection Ordinance: Modified Simple Method Plan: Westfield Road Site Water Resources Area: Development Area Preparers NV Date: 23- Sep -05 Project Drainage Area Designation DA #1 L storm pollutant export in pounds, L = [P(Pj)Rv /12 ] [ C(A)2.72 ] f I (pre) * Rv mean runoff coefficient, Rv = 0.05 + 0.009(1) L(pre) L(post) Pj small storm correction factor, 0.9 % RR Area Type 0.70 I percent imperviousness 20% 0.23 P annual precipitation, 43" in Albemarle 2.34 1.56 A project area in acres in subject drainage area, A = 0.55 1.00 C pollutant concentration, mg /I or ppm target phosphorus 0.12 0.21 f factor applied to RR 0.96 82% Drinking Water Watersheds V required treatment volume in cy, 0.5" over imperv. area = A(1)43560(0.5/12)/27 1.00 RR required removal , L(post) - f x L(pre) 0.12 0.23 %RR removal efficiency, RR100 /L(post) 1.10 82% Other Rural Land Impervious Cover Computation (values in feet & square feet) 1.14 85% Item pre - development Area post - development Roads Length Width subtotal Length Width subtotal 0 0 0 0 0 0 0 0 0 Driveways Length Width no. subtotal Length Width no. subtotal and walks 0 0 0 0 0 0 0 Parking Lots Area 1 Area 2 Area 3 Area 4 Area 1 Area 2 Area 3 Area 4 0 12783.54 Gravel areas Area 1 Area 2 subtotal Area 1 Area 2 subtotal 0 x0.70= 0 0 x0.70= Structures Area no. subtotal Area no. subtotal 0 3731.02 1 3731.02 0 0 0 0 0 Actively - grazed pasture & Area Area yards and cultivated turf 23868.66 x 0.08 = 1909.493 7354.1 x 0.08 = Active crop land Area Area x0.25= 0 x0.25= Other Impervious Areas Area 1 Area 2 Area 3 Area 1 Area 2 Area 3 0 0 Impervious Cover 8% I(pre) Rv(post) V 0.69 26.4 New Development (For Development Areas, existing impervious cover - 20% C f I (pre) * Rv(pre) L(pre) L(post) RR % RR Area Type 0.70 1.00 20% 0.23 0.77 2.34 1.56 67% Development Area 0.35 1.00 0% 0.12 0.21 1.17 0.96 82% Drinking Water Watersheds 0.40 1.00 1 % 0.12 0.23 1.34 1.10 82% Other Rural Land * min. values 1.14 85% Other Rural Land Redevelopment (For Development Areas, existing impervious cover > 20 %) C f I (pre) * Rv(pre) L(pre) L(post) RR % RR Area Type 0.70 0.90 20% 0.23 0.77 2.34 1.64 70% Development Area 0.35 0.85 0% 0.12 0.21 1.17 0.99 85% Drinking Water Watersheds 0.40 0.85 1% 0.12 0.23 1.34 1.14 85% Other Rural Land Area 0 12783.54 0 3731.02 588.328 0 0 72% I(post) rev. 30 May 2002 JMK 'I I Johm-UxAvir- Consulting Engineers I J- L B & B. Building, Waynesboro, Virginia 22980 540- 942 -1161 • FAa:540- 942 -1163 • E- MAIL:jma(a- brucheum.com Preliminary Detention Calculations C -Joh it - — WIV a — --- c iates Consni(ing Engineers Detention: L B. & B Building Waynesboro Virginia 22930 540-942-1161 • FAX: 540-942-1163 • E -MAIL: jma(d�brucheum.com Detention for this site was analyzed as follows. All off -site runoff from the Northeast and Northwest is bypasses the site via existing concrete curbing on the adjoining parcel and along Westfield Road. All off -site runoff to the Southeast and Southwest is down slope from the site and do not contribute any runoff to the site. Requirements for stormwater quantity and quality are met using a network of 4 — 24" 0 underground storage pipes and a Filterra® Stormwater Bioretention Filtration System. The stormwater runoff that will be going through the biofilters and the underground storm water storage pipes includes all of the on -site impervious areas and the majority of the on -site pervious areas. ii ❑ i �_ -- Joh WNair Accnc ' Consulting Engineers Outlet Structure: L B & B Building Waynesboro Virginia 22980 540 -942 -1161 • FAX: 540 -942 -1163 • E -MAIL: jma(a Hydroflow was used to help size the outlet structure. Hydroflow was also used to create Stage /storage and stage /discharge graphs. The outlet structure consists of an 18" Riser (weir) with a 5 "0 low -flow orifice and an 18" outlet barrel. The 5 "0 low -flow orifice was set at Elev. = 440.00 The top of the 18" Riser is set at Elev. = 442.00, which will also serve as the emergency overflow. See Stormwater Outlet Structure detail on sheet C- Hydrograph Summary Report Hyd. No. Hydrograph type (origin) Peak flow (cfs) Time interval (min) Time to peak (min) Volume (cult) Inflow hyd(s) Maximum elevation (ft) Maximum storage (cuft) Hydrograph description 1 Rational 2.13 1 5 846 - - -- - - - -- - - - - -- POST 2 Reservoir 0.63 1 11 830 1 441.26 512 ROUTED FLOW 3 Rational 0.61 1 13 626 - -- -- - - -- - - - - -- PRE 205186 - detention.gpw Return Period: 2 Year Tuesday, Oct 25 2005, 11:23 AM Hydraflow Hydrographs by Intelisolve Hydrograph Plot Hydraflow Hydrographs by Intelisolve Tuesday, Oct 25 2005,11:23 AM Hyd. No. 2 ROUTED FLOW Hydrograph type = Reservoir Peak discharge = 0.63 cfs Storm frequency = 2 yrs Time interval = 1 min Inflow hyd. No. = 1 Max. Elevation = 441.26 ft Reservoir name = Detention -1 Max. Storage = 512 cuft Storage Indication method used. Q (cfs) 3.00 _1 - - - -- - I i I i I i 2.00 1- - -- 1.00 i - 0.00 - - 0.0 0.1 Hyd No. 2 0.2 0.3 0.3 0.4 Hyd No. 1 Hydrograph Volume = 830 cult Q (cfs) - - 3.00 I - - -- - -- - -- rt 2.00 - -- -- -- 1.00 � I � I ,.. _ 0.00 0.5 0.6 0.7 Time (hrs) ROUTED FLOW Hyd. No. 2 -- 2 Yr Hydrograph Plot Hydraflow Hydrographs by Intelisolve Hyd. No. 3 PRE Hydrograph type = Rational Storm frequency = 2 yrs; Drainage area = 0.548 ac Intensity = 3.682 in/hr OF Curve = Albemarle-IDF-HDA-05-03.IDF Friday, Oct 21 2005, 1:22 PM Peak discharge = 0.61 cfs Time interval = 1 min Runoff coeff. = 0.3 Tc by User = 13.00 min Asc/Rec limb fact = 1/1.65 Hydrograph Volume = 626 cuft 0 (Cfs) 1.00 0.90 0.80 0.70 0.60 0.50 0.40 0.30 0.20 0.10 PRE Hyd. No. 3 -- 2 Yr Q (Cfs) 1.00 0.90 0.80 0.70 0.60 0.50 0.40 0.30 0.20 0.10 n nn 0.00 -- 0 5 10 — Hyd No. 3 15 20 25 30 35 Time (min) x 7 " 4- 0.00 -- 0 5 10 — Hyd No. 3 15 20 25 30 35 Time (min) Hydrograph Plot Hydraflow Hydrographs by Intelisolve Hyd. No. 1 Runoff coeff. POST Tc by User Hydrograph type = Rational Storm frequency = 2 yrs. Drainage area = 0.548 ac Intensity = 5.180 in /hr IDF Curve = Albemarle - IDF- HDA- 05- 03.IDF Friday, Oct 21 2005, 1:27 PM Peak discharge = 2.13 cfs Time interval = 1 min Runoff coeff. = 0.75 Tc by User = 5.00 min Asc /Rec limb fact = 1/1.65 Hydrograph Volume = 846 cuft POST Q (cfs) Hyd. No. 1 -- 2 Yr 3.00 2.00 1.00 1 1H Q (cfs) 3.00 2.00 1.00 0.00 15 Time (min) Hyd No. 1 0 5 10 Hydrograph Plot Hydraflow Hydrographs by Intelisolve Hyd. No. 2 Time interval ROUTED FLOW Max. Elevation Hydrograph type = Reservoir Storm frequency = 2 yrs Inflow hyd. No. = 1 Reservoir name = Detention -1 Storage Indication method used. Q (cfs) 3.00 2.00 1.00 1 11 1 Monday, Oct 24 2005, 4:47 PM Peak discharge = 0.63 cfs Time interval = 1 min Max. Elevation = 441.26 ft Max. Storage = 512 cuft ROUTED FLOW Hyd. No. 2 -- 2 Yr 5 10 15 Hyd No. 2 Hyd No. 1 Hydrograph Volume = 830 cuft 20 25 30 35 Req. Stor = 512 cuft Q (cfs) - 3.00 I 1 1 - 1.00 0.00 40 Time (min) Hydrograph Summary Report Hyd. No. Hydrograph type (origin) Peak flow (cfs) Time interval (min) Time to peak (min) Volume (cuft) Inflow hyd(s) Maximum elevation (ft) Maximum storage (cuft) Hydrograph description 1 Rational 2.74 1 5 1,089 - - -- - - - - -- - - - - -- POST 2 Reservoir 0.73 1 11 1,068 1 441.59 703 ROUTED FLOW 3 Rational 0.79 1 13 822 - - -- - - - - -- - - - - -- PRE 205186 - detention.gpw Return Period: 10 Year Tuesday, Oct 25 2005, 11:23 AM Hydraflow Hydrographs by Intelisolve Hydrograph Plot Hydraflow Hydrographs by Intelisolve Hyd. No. 2 Time interval ROUTED FLOW Max. Elevation Hydrograph type = Reservoir Storm frequency = 10 yrs Inflow hyd. No. = 1 Reservoir name = Detention -1 Tuesday, Oct 25 2005, 11:23 AM Peak discharge = 0.73 cfs Time interval = 1 min Max. Elevation = 441.59 ft Max. Storage = 703 cuft Storage Indication method used. Q (cfs) 3.00 2.00 - 1.00 0.00 0.0 Hydrograph Volume = 1,068 cult ROUTED FLOW Hyd. No. 2 -- 10 Yr 0.1 0.2 0.3 Hyd No. 2 Hyd No. 1 0.3 0.4 0.5 0.6 Q (cfs) - 3.00 - 2.00 - 1.00 0.00 0.7 Time (hrs) Hydrograph Plot Hydraflow Hydrographs by Intelisolve Hyd. No. 3 PRE Hydrograph type = Rational Storm frequency = 10 yrs Drainage area = 0.548 ac Intensity = 4.837 in /hr IDF Curve = Albemarle - IDF- HDA- 05- 03.IDF Hydrograph Volume = 822 cuft Q (cfs) 1.00 0.90 0.80 0.70 0.60 0.50 0.40 0.30 0.20 0.10 0.00 0 PRE Hyd. No. 3 -- 10 Yr Q (cfs) 1.00 0.90 0.80 0.70 0.60 0.50 0.40 0.30 0.20 0.10 0.00 35 Time (min) Friday, Oct 21 2005, 1:22 PM Peak discharge = 0.79 cfs Time interval = 1 min Runoff coeff. = 0.3 Tc by User = 13.00 min Asc /Rec limb fact = 1/1.65 5 10 15 20 25 30 Hyd No. 3 Hydrograph Plot Hydraflow Hydrographs by Intelisolve Hyd. No. 1 Runoff coeff. POST Tc by User Hydrograph type = Rational Storm frequency = 10 yrs Drainage area = 0.548 ac Intensity = 6.666 in /hr IDF Curve = Albemarle - IDF- HDA- 05- 03.IDF Friday, Oct 21 2005, 1:24 PM Peak discharge = 2.74 cfs Time interval = 1 min Runoff coeff. = 0.75 Tc by User = 5.00 min Asc /Rec limb fact = 1/1.65 Hydrograph Volume = 1,089 cult Q (cfs) 3.00 2.00 1.00 1 11 Hyd No. 1 5 POST Hyd. No. 1 -- 10 Yr 10 Q (cfs) - 3.00 2.00 1.00 0.00 15 Time (min) Hydrograph Plot Hydraflow Hydrographs by Intelisolve Hyd. No. 2 Time interval ROUTED FLOW Max. Elevation Hydrograph type = Reservoir Storm frequency = 10 yrs Inflow hyd. No. = 1 Reservoir name = Detention -1 Storage Indication method used. Q (cfs) 3.00 2.00 - 1.00 - 0.00 0 Monday, Oct 24 2005, 4:48 PM Peak discharge = 0.73 cfs Time interval = 1 min Max. Elevation = 441.59 ft Max. Storage = 703 cuft ROUTED FLOW Hyd. No. 2 -- 10 Yr 5 10 15 Hyd No. 2 Hyd No. 1 20 25 30 Req. Stor = 703 cult Hydrograph Volume = 1,068 cult 35 Q (cfs) 3.00 2.00 1.00 0.00 40 Time (min) Hydrograph Summary Report Hyd. No. Hydrograph type (origin) Peak flow (cfs) Time interval (min) Time to peak (min) Volume (cult) Inflow hyd(s) Maximum elevation (ft) Maximum storage (cuft) Hydrograph description 1 Rational 3.60 1 5 1,431 - - -- - - - - -- - - - - -- POST 2 Reservoir 1.53 1 10 1,404 1 442.13 928 ROUTED FLOW 3 Rational 1.04 1 13 1,077 - - -- - - - - -- - - - - -- PRE 205186 - detention.gpw Return Period: 100 Year Tuesday, Oct 25 2005, 11:23 AM Hydraflow Hydrographs by Intelisolve Hydrograph Plot Hydraflow Hydrographs by Intelisolve Tuesday, Oct 25 2005, 11:23 AM Hyd. No. 2 ROUTED FLOW Hydrograph type = Reservoir Peak discharge = 1.53 cfs Storm frequency = 100 yrs Time interval = 1 min Inflow hyd. No. = 1 Max. Elevation = 442.13 ft Reservoir name = Detention -1 Max. Storage = 928 cuft Storage Indication method used. Hydrograph Volume = 1,404 cult Q (cfs) 4.00 - 3.00 - 2.00 - 1.00 - 1 1/ 11 ROUTED FLOW Hyd. No. 2 -- 100 Yr 0.1 0.2 0.3 0.3 0.4 0.5 0.6 0.7 Hyd No. 2 Hyd No. 1 Q (cfs) 4.00 3.00 W6 1.00 0.00 0.8 Time (hrs) Hydrograph Plot Hydraflow Hydrographs by Intelisolve Hyd. No. 3 PRE Hydrograph type = Rational Storm frequency = 100 yrs Drainage area = 0.548 ac Intensity = 6.342 in /hr IDF Curve = Albemarle - IDF- HDA- 05- 03.IDF Friday, Oct 21 2005, 1:23 PM Peak discharge = 1.04 cfs Time interval = 1 min Runoff coeff. = 0.3 Tc by User = 13.00 min Asc /Rec limb fact = 1/1.65 Hydrograph Volume = 1,077 cuft Q (cfs) 2.00 - - -- - - - - - - 1.00 - 1 11 5 10 Hyd No. 3 PRE Hyd. No. 3 -- 100 Yr 15 20 25 30 Q (cfs) 2.00 1.00 0.00 35 Time (min) Hydrograph Plot Hydraflow Hydrographs by Intelisolve Hyd. No. 1 Runoff coeff. POST Tc by User Hydrograph type = Rational Storm frequency = 100 yrs Drainage area = 0.548 ac Intensity = 8.762 in /hr IDF Curve = Albemarle - IDF- HDA- 05- 03.IDF Friday, Oct 21 2005, 1:23 PM Peak discharge = 3.60 cfs Time interval = 1 min Runoff coeff. = 0.75 Tc by User = 5.00 min Asc /Rec limb fact = 1/1.65 Hydrograph Volume = 1,431 cuft Q (cfs) 4.00 3.00 2.00 1.00 1 11 1 5 POST Hyd. No. 1 -- 100 Yr 10 Q (cfs) 4.00 Mw rll 1.00 0.00 15 Time (min) Hyd No. 1 Hydrograph Plot Hydraflow Hydrographs by Intelisolve Monday, Oct 24 2005, 4:48 PM Hyd. No. 2 ROUTED FLOW Hydrograph type = Reservoir Peak discharge = 1.53 cfs Storm frequency = 100 yrs Time interval = 1 min Inflow hyd. No. = 1 Max. Elevation = 442.13 ft Reservoir name = Detention -1 Max. Storage = 928 cult Storage Indication method used. Hydrograph Volume = 1,404 cult Q (cfs) 4,00 3.00 2.00 1.00 1 11 1 ROUTED FLOW Hyd. No. 2 -- 100 Yr 5 10 15 20 25 30 35 Hyd No. 2 Hyd No. 1 Req. Stor = 928 cuft 40 Q (cfs) - 4.00 3.00 2.00 1.00 0.00 45 Time (min) r Ir I 4 {y +� SJ } 0 � 4Y ui x +J � x A 1Y � x 7 ti a C � 4 a � a g r� V lY W c ti d u a L 4 +� } � C LL- J a } 0 a ai 0 a a a Q E u C � qt Y t J alo u`. 5- C I O V i N C O U O O Z T C O U E N L U U) aI C L CD O N N 9 T (6 C O �o i dI C O C co LO 0 N U . R. AM P- M i C 0 Q.. � r Y ^�-Y lV L O TT ^ O y ... C13 in IM c 0 U 0 c 0 0 0 Z T c 0 U 0 .c U cn CL LO 0 0 N d N r U T G O G G t"' i r_ pr :P C t3? r fi CL G O G Q�7 'O c0 r N U O O d Cd 1 , IM c 0 U 0 c 0 0 0 Z T c 0 U 0 .c U cn CL LO 0 0 N d N r U T G O G G t"' i r_ pr :P C t3? r fi CL G O G Q�7 'O c0 r N U O O d 2 STORMWATER OUTLET STRUCTURE SCA LL NOT sCAU C d ' MANHOLE ' OPENING ABOVE ` 24" HDPE FROM UNDERGROUND O 1-1 18" HDPE BARREL STORAGE AREA f @ 1 00 K 18" END CAP w� S" ORIFICE INV =440 00 4 S" 5' -0" 6" N -1'_ PRO-LINK W 1 MANIFOLD d Q I LE IS IRAP DOWN 10 BO FI OM OF S7 KUC'I LIRE 10 Q4 d :p PREVENI ELOAHN'G) . 24" -FROM UNDERGROUND PLAN STORAGE AREA N.T.S. V DO I S 1 ANDARD PRECASI MANHOLE "1 OP - f L.A I SLAB 2' - WIDE IOPUNI1 MANHOLE OPENING lop ELLV­ _w ID 0 4 . . d A . zPj V p ELEV -44200 d « \ \ - z2t 7 77 '71111171,-17; FROM UNDERGROUND 1 FROM UNDE 1 STORAGE PIPES l \l 18" END CAP \ INV =440 IO 18" HDPE BARREL INV =440 10 \ \ F 5" OR @ 1.00% \ 44 INV =44000 �✓ a e PROFILE "'f °`° IEL(S"R`NDO� o N.T.S. BO 1 OM Of S I RUCIUR6 10 YREVENI FLOA IING) 2 STORMWATER OUTLET STRUCTURE SCA LL NOT sCAU 1 JohnMcNi i�au-d-Assnciates i Consulting Engineers l 1 L. B. & B. Building, Waynesboro, Vireinia 27980 540- 942 -1161 • FAX: 540- 942 -1163 • E -MAIL: jmala Drainage Maps LEGEND DRAINAGE B Tc PATH OUNDARY � I � \ \ j l I co \ � I N -Q I � I m I� v� f I � 1 � a I D CONDITION N47 °3021 "E 199.90 I ( AREA = 0.548 ACRES No j Z 0 N t \ I I 4�30'21 "W 200.00 f I � PRE DEVELOPE SCALE: 1 " =20' � I � \ \ j l I co \ � I N -Q I � I m I� v� f I � 1 � a I D CONDITION LEGEND DRAINAGE BOUNDARY ex , rn N N v co v BIOFILTER #2 -}-� i l.p Tc PATH N47 0 30'21 T 199.90 S4� 30'21 "W 200.00 BIOFILTER #1 j y � 1 � � E + ' f � t POST DEVELOPE SCALE: 1"=20' D CONDITION �z S ~` _ e t �z S ~` _ e o h conk. ' 2 482 �. J .2942.8 SD 439 conk. 3629.9 5Q • � f oG L 1J�� Pond Report Hydraflow Hydrographs by Intelisolve Friday, Oct 20 2006, 2:15 PM Pond No. 3 - Sediment Trap 1 Pond Data Pond storage is based on known contour areas. Average end area method used. Stage / Storage Table Stage (ft) Elevation (ft) Contour area (sqft) Incr. Storage (cuft) Total storage (cuft) 0.00 437.00 2,050 0 0 1.00 438.00 2,482 2,266 2,266 2.00 439.00 2,943 2,713 4,979 3.00 440.00 3,630 3,287 8,265 Culvert / Orifice Structures Weir Structures [Al [B] [C] [D] [A] [Bl [C] [D] Rise (in) = 0.00 0.00 0.00 0.00 Crest Len (ft) = 9.00 0.00 0.00 0.00 Span (in) = 0.00 0.00 0.00 0.00 Crest El. (ft) = 439.00 0.00 0.00 0.00 No. Barrels = 0 0 0 0 Weir Coeff. = 3.33 0.00 0.00 0.00 Invert El. (ft) = 0.00 0.00 0.00 0.00 Weir Type = Ciplti - - -- Length (ft) = 0.00 0.00 0.00 0.00 Multi -Stage = No No No No Slope ( %) = 0.00 0.00 0.00 0.00 N -Value = .000 .000 .000 .000 Orif. Coeff. = 0.00 0.00 0.00 0.00 Multi -Stage = n/a No No No Exfiltration = 0.000 in /hr (Contour) Tailwater Elev. = 0.00 It Note: Culvert/Orifice outflows have been analyzed under inlet and pullet control. c Stage (ft) 3.00 Stage / Storage Stage (ft) 3.00 0.1 2.00 A 0.00 Z�co 5319 NOR 1.00 0.00 0 ge (cuft) Elevation IN Surface Area ft 2 Average Surface Area ft Difference in Elevation [ft] Incremental Storage ft Sum Storage ft 3 Sum Storage [ac -ft] 437.00 2,050.00 2,071.60 0.10 207.16 437.10 2,093.20 207.16 0.005 2,114.80 0.10 211.48 437.20 2,136.40 418.64 0.010 2,158.00 0.10 215.80 437.30 2,179.60 634.44 0.015 2,201.20 0.10 220.12 437.40 2,222.80 854.56 0.020 2,244.40 0.10 224.44 437.50 2,266.00 1,079.00 0.025 2,287.60 0.10 228.76 437.60 2,309.20 1,307.76 0.030 2,330.80 0.10 233.08 437.70 2,352.40 1,540.84 0.035 2,374.00 0.10 237.40 437.80 2,395.60 1,778.24 0.041 2,417.20 0.10 241.72 437.90 2,438.80 2,019.96 0.046 2,460.40 0.10 246.04 438.00 2,482.00 2,266.00 0.052 2,505.05 0.10 250.51 438.10 2,528.10 2,516.51 0.058 2 ,551.15 0.10 255.11 438.20 2,574.20 2,771.62 0.064 2,597.25 0.10 259.72 438.30 2,620.30 3,031.34 0.070 2,643.35 0.10 264.34 438.40 2,666.40 3,295.68 0.076 2,689.45 0.10 268.95 438.50 2,712.50 3,564.63 0.082 2,735.55 0.10 273.56 438.60 2,758.60 3,838.18 0.088 2,781.65 0.10 278.17 438.70 2,804.70 4,116.35 0.094 2,827.751 0.10 282.77 C: \My Documents \SWM Design Pack 1 10/20/2006 438.80 2,850.80 4,399.12 0.101 438.90 2,896.90 2,873.85 0.10 287.38 4,686.50 0.108 2,919.95 0.10 292.00 439.00 2,943.00 4,978.50 0.114 2,977.35 0.10 297.74 439.10 3,011.70 5,276.24 0.121 439.20 3,080.40 3,046.05 0.10 304.60 5,580.84 0.128 3,114.75 0.10 311.47 439.30 3,149.10 5,892.31 0.135 3,183.45 0.10 318.35 439.40 3,217.80 6,210.66 0.143 3,252.15 0.10 325.22 0.150 439.50 3,286.50 6,535.88 3,320.85 0.10 332 .09 439.60 3,355.20 6,867.96 0.158 3,389.55 0.10 338.96 439.70 3,423.90 7,206.92 0.165 3,458.25 0.10 345.82 439.80 3,492.60 7,552.74 0.173 3,526.95 0.10 352.69 439.90 3,561.30 7,905.43 0.181 3,595.65 0.10 359.57 440.00 3,630. 00 8,265.00 0.190 CAMy Documents\SWM Design Pack 1 10/20/2006