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HomeMy WebLinkAboutDrainage Reports - 07/17/2017' City Of'Fi., GOWN Pins Approved By. ; - ' Date 7- TAIT 61u.0 101., <o.u.0 6163 E. Co my Rood 16, 1o.01ond, CO 80537 ot970161311447 ...,voit.c*m May 11, 2017 ' City of Fort Collins Engineering Division 281 N College Fort Collins, CO 80524 Drainage Letter for the Proposed Site Development located at 2610E Harmony Road, Fort Collins, CO 80528 Lots 8, Front Range Village and Lot 9, Front Range Village First Replat Dear Rick Richter, This drainage letter is to convey the proposed site development conforms to the overall development's ' report, which is titled Final Drainage and Erosion Control Study for Front Range Village, Fort Collins, Colorado prepared by Stantec Consulting Inc. (February, 2007), and will hereafter be referred to as the Master Report. The subject site is currently comprised of two undeveloped lots. Lot 8 is 35,018 square feet (0.80 acre) and Lot 9 is 63,457 square foot (1.456 acre). The site is located in the southeast quarter of Section 32, Township 7 North, Range 68 West of the 6th Principal Meridian, City of Fort Collins, County of Larimer, ' State of Colorado, on the northwest corner of Harmony Road and Corbett Drive. The site lies on Lots 8 & 9 of the Front Range Village Subdivision. It is bound to the south by the Harmony Corporate Center, to the east by a detention pond that serves a portion of the subdivision, and to the north and west by Council Tree Avenue. Proposed improvements to the site include a building to be constructed on the southeast edge of the site with a total footprint of about 13,264 square feet. The site will have 140 parking spaces, internal ' sidewalks, utility services and landscaping. The site consists of Type C Soils, Nunn clay loams, and existing fill from previous development rough grading. This site is located in flood Zone X, "Areas determined to be outside the 0.2% annual chance floodplain." ' Existing drainage patterns convey all flows to drainage pond F bordering the site along the east property line. The Master Report was calculated using an overall imperviousness of 85-percent for this basin. The proposed lot is accounted for in the Final Drainage Report as a portion of Basin 500, which has a total area of 3.08 acres. Basin 500 has a Clo of 0.84, C1oo of 0.84, Tcio of 9.4 minutes, Tctoo of t 5.0 minutes, and flows of Qio=9.88 cfs and Q1oo=30.06 cfs. Lot 8 and 9 have an area of 2.26 acres, so the weighted averages of the flows for pre -developed Lot 8 and 9 are Qto = 7.25 cfs and Qtoo=22.06 cfs. The post developed site will discharge at rates less than or equal to these flows in the 10 and 100 year ' storm events. Per previous design documents, the property to the south of this development has a flow path directed through the site. The overflow enters the site through the SW corner and is currently conveyed through the lot within a swale at the southern property line. There is an existing drainage easement along the south side of the property that provides a path for these flows. This swale will be eliminated with the proposed development. In order to accommodate the existing drainage conditions, there will be a proposed area inlet to convey it through the onsite storm drain system. The pipes have been sized to convey the entire 10 year flow contributing to the existing upstream basin. In the event that the proposed inlet is clogged, flows will spill into the parking lot of the adjacent basin and follow proposed drainage patterns as described within this report. Post -development drainage will be conveyed via sheet flow to two 4' curb inlets and four area inlets. These facilities will be connected by 6", 12" and 18" HDPE and 24" RCP pipes which will convey runoff to the existing drainage detention pond F located to the east of the property site. From this pond within the Front Range Village system, the runoff from the site will ultimately discharge into the Cache la Poudre. Pipe sizing calculations are attached to this letter for reference. Post -development conditions consist of a proposed building consisting of a fitness center that includes associated parking lot and landscaped areas. The post development property consists of ten on -site sub -basins and two off -site sub -basins. See the Post Development Drainage Plan for additional information. Post -development Sub -basin D1 consists of 0.49 acres of parking lot, paved walkway and landscaping on the south portion of the property and is 74% impervious. Runoff from this basin drains into a proposed CDOT type 13 area inlet, located in the middle of the parking area. Flows that enter this inlet are conveyed to the existing detention pond. Sub -basin D1 discharges at a rate of 1.45 cfs in the 10- year storm event and 4.09 cfs in the 100-year storm event. Post -development Sub -basin D2 consists of 0.35 acres of parking lot and landscaped area on the northwest property line and is 88% impervious. Runoff from this basin drains into a proposed 4' curb inlet with vertical opening, located on a landscaping island, and proposed 18" storm drain. The storm drain discharges into the existing drainage pond F located east of the property. Sub -basin D2 discharges at a rate of 1.12 cfs in the 10-year storm event and 3.05 cfs in the 100-year storm event. Post -development Sub -basin D3 consists of 0.35 acres of parking lot, paved walkway and landscaped area on the north portion of the property and is 79% impervious. Runoff from this basin drains into a proposed 4' curb inlet with vertical opening, located on the east side of the parking lot, and proposed 24" storm drain. The storm drain discharges into the existing drainage pond F located east of the property. Sub -basin D3 discharges at a rate of 1.24 cfs in the 10-year storm event and 3.43 cfs in the 100-year storm event. ' Post -development Sub -basin D4 consists of 0.32 acres of proposed building rooftop and is 90% impervious. Runoff from this basin drains via sheet flow to roof drains and discharges to Sub -basin D5 and ultimately discharges to drainage pond F to the east of the property. Sub -basin D4 discharges at a rate of 1.09 cfs in the 10-year storm event and 2.90 cfs in the 100-year storm event. Post -development Sub -basin D5 consists of 0.08 acres of landscaping on the south and east side of the t proposed building and is 2% impervious. Discharge from this area drains into a proposed are inlet and into existing drainage pond F to the east. Sub -basin D5 discharges at a rate of 0.07 cfs in the 10-year storm event and 0.41 cfs in the 100-year storm event. ' Post -development Sub -basin D6 consists of 0.03 acres of landscaping in the northeast corner of the property and is 2% impervious. Runoff from this basin flows offsite to the existing drainage pond F to the east of the property and then follows the same drainage patterns. Sub -basin D6 discharges at a rate of 0.02 cfs in the 10-year storm event and 0.13 cfs in the 100-year storm event. Post -development Sub -basin D7 consists of 0.04 acres of landscaping in the northeast corner of the property and is 2% impervious. Runoff from this basin flows onto Council Tree Avenue and then to an ' existing curb inlet that conveys flows to the pond. Sub -basin D7 discharges at a rate of 0.04 cfs in the 10-year storm event and 0.23 cfs in the 100-year storm event. Post -development Sub -basin D8 consists of 0.07 acres of landscaping and driveway along the north ' side of the property and is 37% impervious. Runoff from this basin flows onto existing Pond F to the 1 I ' east of the property and then follows existing drainage patterns. Sub -basin D8 discharges at a rate of 0.16 cfs in the 10-year storm event and 0.50 cfs in the 100-year storm event. ' Post -development Sub -basin D9 consists of 0,35 acres of paved parking areas and landscaping along the south side of the property and is 82% impervious. Runoff from this basin flows onto a proposed area inlet near the south side of the property and then to the detention pond. Sub -basin D9 discharges at a rate of 1.12 cfs in the 10-year storm event and 3.05 cfs in the 100-year storm event. ' Post -development Sub -basin D10 consists of 0.12 acres of landscaping along the south side of the property and is 2% impervious. Runoff from this basin flows onto a proposed area inlet and then to the detention pond. Sub -basin D10 discharges at a rate of 0.10 cfs in the 10-year storm event and 0.62 cfs ' in the 100-year storm event. Post -development Sub -basin OFF1 consists of 0.05 acres of landscaping and driveway along the north ' side of the property and is 2% impervious. Runoff from this basin flows onto existing Pond F to the east of the property and then follows existing drainage patterns. Sub -basin OFF1 discharges at a rate of 0.04 cfs in the 10-year storm event and 0.25 cfs in the 100-year storm event. ' Post -development Sub -basin OFF2 consists of 0.08 acres of landscaping along the south side of the property and is 2% impervious. Runoff from this basin flows into curb and area inlets and to Pond F. Sub -basin OFF1 discharges at a rate of 0.07 cfs in the 10-year storm event and 0.41 cfs in the 100-year storm event. The master drainage report delineated a 0.18 acre basin 10 that discharges at 1.16 cfs in the 100 year storm. Flows from this basin currently sheet flow into the existing detention pond. Site improvements include removing the existing driveway that acts as the flow path for this basin and replacing it with sidewalk, curb and gutter, and landscaping. There will be a sidewalk chase through this region to continue to convey flows in their same path. These flows will enter the propsed area inlet shown on the drainage plan before flowing into the pond. The overall post -development site imperviousness is 66%, compared to the 85% imperviousness that was assumed with the master drainage report. After improvements, the site will discharge at a total rate of 6.38 cfs in the 10 year storm event, generating a decrease of 0.87 cfs flow than anticipated conditions which was 7.25 cfs. In the 100-year event, the total site discharge rate will be 18.36 cfs, compared to 22.06 cfs from the original development build -out, generating 3.70 cfs less than anticipated conditions. The drainage from the adjacent property will spill into the proposed area inlet on the west side of the property and flow through the proposed storm drain system into the detention pond. These pipes facilities were sized to safely convey the 10 year storm flows. Pipes larger than called for in design were installed. In the event of the 100 year storm, flows in this swale spill over the curb into basin D9 and to the curb inlet on the south side of the parking lot. In this situation, there will be 0.91' of ponding at the inlet. Required detention for this site has been accommodated with the overall design for this subdivision via the detention pond adjacent to the property. The overall imperviousness of the site will be decreased from the anticipated conditions assumed in the original drainage report for the subdivision. Overall the site will see a decrease of 19% imperviousness from the assumed value in the master report, and a total runoff in the 100-year storm event of 13.57 cfs, which is 8.49 cfs less than the anticipated 22.06 cfs. Water quality will be provided via detention ponds that were constructed with the ' overall development. Overflow from the adjacent property has been passed through the proposed site to maintain the intent of thtpL=ipus design. Sincerely, UCH, ' Alex(lo Director RUNOFF COEFFICIENT CALCULATIONS Project Name: C01303D - Front Range Village - Lot 8 & 9 Calculated By: KV Check By: AH Date: 5/11 /2017 RECOMMENDED RUNOFF COEFFICIENT AND PERCENT IMPERVIOUS LAND USE % IMPERVIOUS Runoff Coefficients, C-value 10 YEAR 100 YEAR LANDSCAPE 2 0.22 0.52 DRIVES AND WALKS 90 0.87 0.91 ROOFS 90 0.87 0.91 POST -DEVELOPMENT CONDITIONS: AREA DESIGN A(LAND.) AC A(D&W) AC A(ROOFS) AC A(TOTAL) AC C10 C100 % IMPERVIOUS D1 0.09 0.4 .0 .49 0.75 0.84 4 D2 0.03 0.32 0.00 0.35 0.81 0.88 82 D3 0.05 0.35 0.00 0.40 0.79 0.86 79 D4 0.00 0.00 0.32 0.32 0.87 0.91 90 D5 0.08 0.00 0.00 0.08 0.22 0.52 2 D6 0.03 0.00 0.00 0.03 0.22 0.52 2 D7 0.04 0.00 0.00 0.04 0.22 0.52 2 D8 0.04 0.03 0.00 0.07 0.48 0.68 37 D9 0.03 0.32 0.00 0.35 0.81 0.88 82 D10 0.12 0.00 0.00 0.12 0.22 0.52 2 OFF1 0.05 0.00 0.00 0.05 0.22 0.52 2 OFF2 TOTAL: 2.38 WEIGHTED: 0.79 66 1 Runoff coefficients and percent impervious per Urban Drainage and Flood Control District, Volume 1 - Dated January 2016 `CONTRIBUTING OFFSITE AREAS DRAINING INTO DETENTION BASIN BUT OUTSIDE OF PROPOSED PROPERTY. 10-YEAR INDIVIDUAL BASIN FLOWS Project Name: C01303D - Front Range Village - Lot 8 & 9 Calculated By: KV ' Check By: AH Date: 5/11 /2017 POST -DEVELOPMENT CONDITIONS: SUB -BASIN DATA DIRECT RUNOFF CONTRIBUTING BASINS BASIN AREA acre C10 EFFECTIVE AREA acre I in/hr SUB BASIN Q cfs D1 0.49 0.75 0.37 3.93 1.45 D2 0.35 0.81 0.29 3.93 1.12 D3 0.40 0.79 0.32 3.93 1.24 D4 0.32 0.87 0.28 3.93 1.09 D5 0.08 0.22 0.02 3.93 0.07 D6 0.03 0.22 0.01 3.93 0.02 D7 0.04 0.22 0.01 3.93 0.04 D8 0.07 0.48 0.03 3.93 0.13 D9 0.35 0.81 0.29 3.93 1.12 D 10 0.12 0.22 0.03 3.93 0.10 OFF1 0.05 0.22 0.01 3.93 0.04 OFF2 0.08 0.22 0.02 3.93 0.07 TOTAL: 6.49 TOTAL ONSITE: 6.38 ' Q10= C*I*A Intensity values taken from City of Fort Collins Municipal Code Stormwater Criteria Manual Volume 1 Table RA-7 for a Tc of 9 min. ' 100-YEAR INDIVIDUAL BASIN FLOWS Project Name: C01303D - Front Range Village - Lot 8 & 9 Calculated By: KV ' Check By: AH Date: 5/11 /2017 POST -DEVELOPMENT CONDITIONS: SUB -BASIN DATA DIRECT RUNOFF CONTRIBUTING BASINS BASIN AREA acre C100 EFFECTIVE AREA acre I in/hr SUB BASIN Q cfs D1 0.49 0.84 0.41 9.95 4.09 D2 0.35 0.88 0.31 9.95 3.05 D3 0.40 0.86 0.34 9.95 3.43 D4 0.32 0.91 0.29 9.95 2.90 D5 0.08 0.52 0.04 9.95 0.41 D6 0.03 0.52 0.01 9.95 0.13 D7 0.04 0.52 0.02 9.95 0.23 D8 0.07 0.68 0.05 9.95 0.45 D9 0.35 0.88 0.31 9.95 3.05 D10 0.12 0.52 0.06 9.95 0.62 OFF1 0.05 0.52 0.03 9.95 0.26 OFF2 0.08 0.52 0.04 9.95 0.41 TOTAL: 19.04 TOTAL ONSITE: 18.36 Q100= C*I*A Intensity values taken from City of Fort Collins Municipal Code Stormwater Criteria Manual Volume 1 Table RA-7 for a Tc of 5min. I Inlet Report Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3De by Autodesk. Inc. South Curb Inlet Monday, May 8 2017 Curb Inlet Calculations Location = Sag Compute by: Known Q Curb Length (ft) = 4.00 Q (cfs) = 8.58 Throat Height (in) = 8.00 Grate Area (sqft) _ .0. Highlighted Grate Width (ft) _ .0. Q Total (cfs) = 8.58 Grate Length (ft) _ .0. Q Capt (cfs) = 8.58 Q Bypass (cfs) _ -0- Gutter Depth at Inlet (in) = 10.94 Slope. Sw (ft/ft) = 0.050 Efficiency (%) = 100 Slope. Sx (ft/ft) = 0.050 Gutter Spread (ft) = 11.57 Local Depr (in) = 2.00 Gutter Vel (ft/s) _ .0. Gutter Width (ft) = 1.00 Bypass Spread (ft) _ .0. Gutter Slope (%) _ .0. Bypass Depth (in) _ .0. Gutter n-value = .0- 2 091 t 0 0 57 Inlet Report Hydraf low Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc West Area Inlet in 100 year storm<Name> Drop Grate Inlet Location Curb Length (ft) Throat Height (in) Grate Area (sqft) Grate Width (ft) Grate Length (ft) Gutter Slope, Sw (ft/ft) Slope. Sx (ft/ft) Local Depr (in) Gutter Width (ft) Gutter Slope (%) Gutter n-value rn Cs, ors r!K J a = Sag _ -0- _ -0- 1.73 = 1.88 = 3.27 = 0.050 = 0.050 = 2.00 1.00 _ .0- _ .0- Calculations Compute by: Q (cfs) Highlighted Q Total (cfs) Q Capt (cfs) Q Bypass (cfs) Depth at Inlet (in) Efficiency (%) Gutter Spread (ft) Gutter Vel (ft/s) Bypass Spread (ft) Bypass Depth (in) Monday. May 8 2017 Known Q = 8.52 = 8.52 = 8.52 _ -0- = 10.08 100 = 35.48 _ -0- _ -0- _ .0. 1 11 LI J —1 L dVW MS" 30VNiVbO 43SOdOLd mct�u n 30•lllll 3JNVr 1lD11s �/ i 1 n • ON 93Y„ 73dOrd r3AVO � � � • f t a f, Y I © I 1 1 I 1 1 uj> OLis our Id . i � � p _ � Z : _ " ' ' _ _ _ = R A _ � _ s X X C X' t ° : : 9 : i . s _ R. • � i R - X R 3 . _ _ ... . _ _ ... M1 « .. -... .. .. _ 1 11VIL =.^..^ BZSOG JO SNMOi _dC i CVOH d3l931ZONv 3nN3AV 33d- '+'00 NOSN3HS630-00VNb 101 3WIU 3ONvb 140b3 ONv Y 10l 30vnIA 3ONvb 1 3J VNI VM01N3 WdOl3A30.1SOd $s� dd�dgodo oti � d c d d d_ o yy_ yga8ac2222irl. u d d d G d 0 0 0 0 0 g a kt d 6 dd d 0 d o a o 0$ 8 �ssaasessso5n i e ii e e I e e IDLF E 2 Fir I I I1 I HYDROLOGIC SUMMARY TABLE Design Point Basins Are& (ecm) C0m90aft C" • I Ge I cfe CIM cM1 100 100 383 0B5 5.24 38.14 101 1D1 0.18 083 On 1.79 102 IG2 057 0]B •203 S39 103 103 241 084 917 236E 104 104 045 095 207 4.46 106 105 091 084 1361 9M 108 106 151 0 86 14 83 1216 1W iW 037 089 1.51 368 108 108 040 095 1.07. 4.02 to 109 167 am 6.78 1 16.57 110 110 062 070 2.16 EI 111 Ill IM 1 087 437 1023 112 112 083 O.BB i306 7.A 113 113 100 09D L4 41 9,99 114 114 100 090 4.SO 9.0 116 115 127 0911 559 12M 116 116 070 095 326 6% 117 117 1.69 089 29 16J9 tie 118 1.03 B2 1027 119 lt9 0.91 52 8] 120 120 059 r7-092 2.64' 588. 121 11 042 081 16 420 122 in 086 071 261 630 1" 123 124 060 L2B3+ 7.57 124 124 0.11 005 In 1.14 126 125 D31 080 .181 310 120 126 0.67 _ 095 3.03 Sn 130 130 JOB 0.0 98 1072 131 131 0.01 0.87 .Bit 675 437. 132 023 00 1.05 2.26 133 In 0.14 095 AS 14D 134 134 082 0% 79 8AS 130 135 D39 070 31 3.38 136 136 On 095 65 3.55 137 137 047 0.95 .19 4.71 130 138 1.84 0.91 .19 IEEI 138 139 1.70 ON ,93 10.63 140 140 on O.M 0.15 BAD 141 141 3.28 095 ISM 32.43 IQ 142 1.23 00 .61 1227 In 143 490 076 18M 48.13 In 150 3.36 065 10 23N lei 151 1.40 _ 062 84 -it DO too leg 163 065 ILES 1623 161 181 0.97 081 .77 962 162 162 0.T7 O.BO 338 768 163 163 065 0.95 2.99. 644 -164 lea 1.50 0 .Q,pT_ 19:87_ 108 166 O55 0.91 24b 541 2N 200 2.74 0.85 :104' 27.24 201 201 1.36 "ON ]0� 1355 202 202 032 0.95 49 $ 203 203 0.10 0.84 0.40, Oet? 204 204 024 0.95 1.t1 2.30 206 205 037 0,95 470' 3.55 208 206 032 092 142 3.16 2p7 207 122 0.78 023' 1191 208 208 0.29 0.94 34, 2.91 2D9 208 0,16 083 T1' 1.50 2f0 210 0.39 0.91 1.73 3.91 211 211 On 0.90 448 382 212 212 0.44 0.95 2.04' 4.39 111 213 1.71 ON 682 1701 214 214 1.12 0.89 4,89 11.19 215 215 in 0.51 53 10.15 218 216 016 0.95 0.75 let 217 217 141 0.95 650. 13.99 218 218 0.23 0.95 1.08 232 219 219 040 095 167 4.01 220 220 TOT 091 43 19.05 221 221 LOW 072 .36 9.31 300 300 1 0.55 0W 1,19 3,50 301 301 1.38 087 0,45 1372 302 302 021 095 097 209 303 BOB 0.30 OM 0_95 2.50 304 306 304 3 5 0.28 031 O95 095 _-� p.20 143 _•. 2.78 3' 000 DOS 0,69 0.90 11.02 6.86 307 307 0.81 060 16 610 400 400 on 0,95 21, 2% at 401 030 095 138 2.86 402 402 204 087 8281 2029 403 AM on 0OF 13V 324 401 404 1.75 OW 331 1745 406 1 406 1.16 on 6,041 11.52 4061 405 I'll ON4A7 1109 407 1 407 1 D.9D OM 5 e._99- "a 408 1l2 O.BB 30 1714 409 ROD 1.Be ON .BB 1961 410 410 038 On 71 374 411 A11 028 OM 1.20 279 412 412 434 095 0 43,19 413 413 0.37 OA .38 3.56 414 414 1.12 062 7 77 500 6M 3M 08A 3006 B01 501 085 0.65 28 682 602 502 1.13 125 087 03. 076 32870 503 51 074 21 8.75 504 5G4 O6] 731 606 51 0.91 822 1912. POND SUMMARY TABLE FOODS Towl Vol. Roal. Vol. Provided IN-Yr WBEL aai (aon) - (6 A TOM a 48 4927 SO 9 2.23 3.09 4M 79 C 137 r 196 493S39 0 I9776 t 2312 426.16 E F 092 69_ 1 99 1.93 4825. 12 I927.Ofi Pen on 505 544 4921 EGEND I4 RILM-CFWAr PROPOSED FL4 E EVENING CONTOURS ! NEW STI ORAN WITH M"N EXISTING STCIM ORAN --I PROPOSED SMIF PROPOSED AVERAGE STREET SLOPE DIRECTION OF FLOW DESIGN PANT 0 Is alleffies DRAINAGE BARK 9WHOARV 30 NOBASIN NUMKR AC. - BASIN AREA (IN AGREES) z w W a (7 ABC W J z FOR DRAINAGE REVIEW ONLY IS. DID ❑ NOT FOR CONSTRUCTION �O z DO Q: DO LEI 01 Oi City of Fort Collins, Colorado m UTILITY PLAN APPROVAL City Engineer Nis PMniH5ea1 CHECKED BT: Water 6 Wmte.ater Utility Dote CHECKED BY: Stormeater Utility Dole CHECKED BY: 100% PLANS PaM3 & Recreation Gate CHECKED BY: NOT FOR CONSTRUNTIM Traffic En9imer Dale JoI=7 CHECKED BY: Date THESE PLAINS HAVE BEEN RENEWED BY THE LOLL ENTITY FOR CONCERT ONLY. THE REVIEW ODES NOT IMPLY RESPONSIBILITY BY THE RENEWING DEPMTIIEM, ME LOCAL ENTTY ENGINEER, OR THE LOCAL ENIF Y FOR ACCURACY AND CORRECTNESS OF n wn xunWe.. TIE CALCULMONS. FURTHERMORE. THE RENEW DOES Fe, NI C-151 Ma NOT IMPLY FIAT QUANTITIES OF ITEMS ON THE PLAINS ME THE FINAL QWMITIES REQUIRED. THE REVIEW - ---- - SHAIL NOT BE CONSTRUED IN MY REASON AS �Ya- •� '= A.CCEPTMCE OF FINMCOL RESPONSIBIIM W THE )YAMDO LOCAL EMM FOR ADDITIONAL QUANTTES OF ITEMS Drayint o. C-151 SHOWN "I MY BE REQUIRED DURING THE Revlston &kw CONSTRUCTION PHASE. () 23 Of 139 GENERAL NOTES LEGEND pNENNONS ARE ERCY OMTF FLOW M TO RLM LINE ESS OW NDTED/SHCWi. CCNNACTOR TO "I" ALL HMZMTAL DINENSIMS WA ARCRHECM& SD PROPOSED STORM DRAIN PLANS AND NOTE MY )MIEPANCIES PRIM RI CONS JUCI. PROPERtt LINE SEE ARCHITECTURAL SITE PLW FOR ALL BUILDING AND STMICTURE DETAILS PEW DEVELOPMENT MANAGE BARN SEE INUIODUAL FOUNDATKNI RAN FOR ALL PRECISE BUIWNC CIMENSM& ALL SGNS TO MATCH SME 6 EMSRNC 9GNS ON SITE. A = BASIN DESIGNATION B C B AREA IN ACRES C = X IMPERVIOUSNESS STORMWATER RUNOFF NOTES TOTAL LOT AREA: 2.26 ACRE TOTAL DISTURBED AREA: 2.42 ACRE S PRE -DEVELOPMENT X IMPERVIOUS: 2% POST -DEVELOPMENT % IMPERVIOUS: 66% gFg s� POST -DEVELOPMENT ONSITE 10-YR STORM RUNOFF: 6.38 CFS a POST -DEVELOPMENT ONSITE 100-YR STORM RUNOFF: 18.36 CFS SUMMARY RUNOFF TABLE BASIN ID CONTRIBUTING AREA ACRES C VALUE 100YR PEAK j0 (CFS AK 100YR (CFS) 01 0.49 0.84 1.45 4.09 D2 0.35 0.88 1.12 3.05 D3 0.40 0.86 1.24 3.43 D4 0.32 0.91 1.09 2.90 D5 0.08 0.52 0.07 0.41 D6 0.03 0.52 1 0.02 0.13 D7 0.04 0.52 0.04 0.23 D8 0.07 0.68 0.13 0.45 D9 0.35 0.88 1.12 3.05 D10 0.12 0.52 0.10 0.62 OFF1 0.05 0.52 0.04 0.26 OFFS 1 0.08 0.52 0.07 0.41 C N K LL N W O ~ O J Q W K Zg w IY J >ZW o z a 3w< W 8 N C �CL wo 29w O LL au< LU > �2w ILL 0 F�� � F J 0 c0 z 5 is Q. 0 0 i Z D 9W w PREPARED UNDER THE SUPERMSION D< TAIT A ASSOCIATES INC. LL BCILE: 1'. ]II' IY f ptt FIXIi CLANS COlptA00 'Ys L UTILITY PLAN APPROVAL3p ENpNEEH DALECHECKED BY: MALWATER & W.6 AVER UnuTY DATE CHECKED BY: SIpNWATER U1MItt DATE mm„ ; E "Im D R N am LX a •