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HomeMy WebLinkAboutWPO201400072 Calculations 2014-12-04 IN CHICK-FIL-A RICHMOND ROAD ALBEMARLE COUNTY, VIRGINIA DRAINAGE CALCULATION PACKAGE ,..tetwx,,Nko 0-47:01.7c:f 1.1"4 , or • LT:— DECEMBER 04, 2014 :150 )4.004"1•01 jvb IN 4)64144,tivTAL!,c,'' . WO #22100 Prepared by: HORTON & DODD, P.C. 300 George Washington Hwy N. Chesapeake, VA 23323 -by 4.• Table of Contents 1.0 General Site Narrative 2.0 Erosion and Sediment Control 2.1 Erosion and Sediment Control Narrative 2.2 Temporary Sediment Trap Calculations 3.0 Stormwater Quality 3.1 Stormwater Quality Narrative 3.2 Performance Based Water Quality Calculations 4.0 Stormwater Quantity 4.1 Stormwater Quantity Narrative 4.1.1 Composite CN and Weighted C Determinations 4.1.2 SCS Runoff Hydrographs 4.2 Reservoir (Routing) Hydrographs 4.3 Storm Sewer Design Calculations 4.3.1 Post-Developed Tc Calculations 4.3.2 Storm Sewer Tabulation Reports 4.3.3 Design Velocity Calculations INSERTS: A. Geotech Report 1.0 General Site Narrative The site, located at 1626 Richmond road, currently encompasses a land area of approximately 1.40 acres. The site was previously an Aunt Sara's Pancake House. The existing facility (now vacant) is ••• proposed to be demolished along with the existing parking lot, sidewalks, curb and gutter to provide the necessary space to construct a new Chick-fil-A restaurant with drive-thru. A boundary line adjustment plat, prepared concurrent to these site development plans, proposes expanding the 1.40 acre parcel to encompass a land area of approximately 1.84 acres. A special use permit (SP-2013-20) specific to the drive-thru was sought and obtained. Conditions associated with the special use permit are illustrated on the Civil Cover Sheet (Sht. C-1.0) of the plans. The subject parcel is situated in the HC (Highway Commercial) zoning district. The site is also contained in the County's Entrance Corridor Overlay area. Site improvements to support the proposed 4,835 square foot restaurant include parking & drive aisles, sidewalks, curb & gutter, a refuse pad & enclosure, retaining walls and a stormwater collection /conveyance/detention system. Additionally offsite improvements are proposed which include closing a portion of North Pantops Drive (existing private road) to eliminate the intersection of N. Pantops and Richmond Road. Access to adjacent properties served by N. Pantops drive will be maintained. Existing Luxor Road (also a private road) is proposed to be extended to the south and south west to intersect Richmond Road across from State Farm Boulevard. Two new traffic signal poles are proposed to be constructed at the new intersection. A segmented block retaining wall is proposed to facilitate the Luxor Road extension. A second retaining wall is proposed on-site just southwest of the drive-thru lane. In conjunction with the Luxor road extension, the developer proposes extending the existing 8" waterline that currently terminates at a blow-off just east of the intersection of north Pantops Drive and Luxor Road (near the existing pump station). The waterline extension is proposed to terminate at a new public fire hydrant. Domestic and irrigation services to support the proposed restaurant will connect to the new 8" line. Sanitary sewer will be collected and conveyed through a 4" lateral to an existing cleanout along Richmond Road. Currently, the site is accessed off North Pantops Drive via one of two entrances. Both existing entrances will be demolished. Two new entrances are proposed off of the proposed Luxor Road Extension. 2.0 Erosion and Sediment Control 2.1 Erosion and Sediment Control Narrative CHICK-FIL-A RESTAURANT; 1626 RICHMOND ROAD, ALBEMARLE COUNTY, VA. PROJECT DESCRIPTION: THE SITE, LOCATED AT 1626 RICHMOND ROAD, CURRENTLY ENCOMPASSES A LAND AREA OF APPROXIMATELY 1.40 ACRES. THE SITE WAS PREVIOUSLY AN AUNT SARA'S PANCAKE HOUSE. THE EXISTING FACILITY (NOW VACANT) IS PROPOSED TO BE DEMOLISHED ALONG WITH THE EXISTING PARKING LOT, SIDEWALKS, CURB AND GUTTER TO PROVIDE THE NECESSARY SPACE TO CONSTRUCT A NEW CHICK-FIL-A RESTAURANT WITH DRIVE-THRU. A BOUNDARY LINE ADJUSTMENT PLAT, PREPARED CONCURRENT TO THESE SITE DEVELOPMENT PLANS, PROPOSES EXPANDING THE 1.40 ACRE PARCEL TO ENCOMPASS A LAND AREA OF APPROXIMATELY 1.84 ACRES. SITE IMPROVEMENTS TO SUPPORT THE PROPOSED 4,835 SQUARE FOOT RESTAURANT INCLUDE CLOSING A PORTION OF NORTH PANTOPS DRIVE (EXISTING PRIVATE ROAD) TO ELIMINATE THE INTERSECTION OF N. PANTOPS AND RICHMOND ROAD. ACCESS TO ADJACENT PROPERTIES SERVED BY N. PANTOPS DRIVE WILL BE MAINTAINED. EXISTING LUXOR ROAD (ALSO A PRIVATE ROAD) IS PROPOSED TO BE EXTENDED TO THE SOUTH AND SOUTH WEST TO INTERSECT RICHMOND ROAD ACROSS FROM STATE FARM BOULEVARD. TWO NEW TRAFFIC SIGNAL POLES WILL BE ERRECTED AT THE NEW INTERSECTION. A SEGMENTED BLOCK RETAINING WALL IS PROPOSED TO FACILITATE THE LUXOR ROAD EXTENSION. A SECOND RETAINING WALL IS PROPOSED ON-SITE JUST SOUTHWEST OF THE DRIVE- THRU LANE. IN CONJUNCTION WITH THE LUXOR ROAD EXTENSION, THE DEVELOPER PROPOSES EXTENDING THE EXISTING 8" WATERLINE THAT CURRENTLY TERMINATES AT A BLOW-OFF JUST EAST OF THE INTERSECTION OF NORTH PANTOPS DRIVE AND LUXOR ROAD (NEAR THE EXISTING PUMP STATION). THE WATERLINE EXTENSION IS PROPOSED TO TERMINATE AT A NEW PUBLIC FIRE HYDRANT. DOMESTIC AND IRRIGATION SERVICES TO SUPPORT THE PROPOSED RESTAURANT WILL CONNECT TO THE NEW 8" LINE. SANITARY SEWER WILL BE COLLECTED AND CONVEYED THROUGH A 4" LATERAL TO AN EXISTING CLEANOUT ALONG RICHMOND ROAD. CURRENTLY, THE SITE IS ACCESSED OFF NORTH PANTOPS DRIVE VIA ONE OF TWO ENTRANCES. BOTH EXISTING ENTRANCES WILL BE DEMOLISHED. TWO NEW ENTRANCES ARE PROPOSED OFF OF LUXOR ROAD EXTENSION. OTHER SITE IMPROVEMENTS INCLUDE PARKING, SIDEWALKS, CURB & GUTTER, A REFUSE PAD & ENCLOSURE, AND A STORMWATER COLLECTION /CONVEYANCE/ DETENTION SYSTEM (DISCUSSED BELOW). .. EXISTING SITE CONDITIONS: THE EXISTING SITE CONSISTS OF AN ASPHALT PARKING LOT AND AN ABANDONED BUILDING. STORM WATER RUNOFF FROM THE SITE FLOWS EITHER TO THE SOUTH/SOUTHWEST (TO AN EXISTING u,,, ROADSIDE DITCH ALONG RICHMOND ROAD) OR TO THE NORTHWEST WHERE IT IS CAPTURED BY EXISTING CURB INLETS IN NORTH PANTOPS DRIVE. THE PROPERTY LIES IN FLOOD ZONE "X"(AREAS DETERMINED TO BE OUTSIDE THE 0.2%ANNUAL CHANCE FLOODPLAIN), AS SHOWN ON THE FLOOD .. INSURANCE RATE MAP (FIRM), MAP NUMBER 51003CO289D, EFFECTIVE DATE: FEBRUARY 4, 2005. ADJACENT AREAS: THE SITE IS BOUND TO THE NORTHWEST BY NORTH PANTOPS DRIVE, TO THE NORTHEAST AND SOUTH BY THE MARTHA JEFFERSON EAST MEDICAL OFFICE PARK, AND TO THE WEST/SOUTHWEST BY "`• RICHMOND ROAD. MEDICAL BUILDINGS BORDER THE PROPERTY TO THE EAST AND SOUTH. THE WESTERN PROPERTY LINE IS ADJACENT TO THE RICHMOND ROAD RIGHT-OF-WAY. .. OFF-SITE AREAS: .. OFFSITE AREAS TO BE DISTURBED INCLUDE AREAS WITH EXISTING UTILITY EASEMENTS (TO FACILITATE THE PROPOSED PUBLIC WATERLINE EXPANSION), PORTIONS OF THE MARTHA JEFFERSON EAST OFFICE PARK SITE TO FACILITATE THE LUXOR ROAD EXTENSION, PORTIONS OF THE NORTH PANTOPS DRIVE PRIVATE INGRESS/ EGRESS EASEMENT (AS NECESSARY TO CONSTRUCT IMPROVEMENTS IN N. PANTOPS DRIVE), AND WORK IN AND ALONG THE EASTERN SHOULDER OF RICHMOND ROAD TO FACILITATE CLOSING PORTIONS OF PANTOPS DRIVE, DITCH REGRADING / ® SHOULDER IMPROVEMENTS, THE NEW TRAFFIC SIGNAL POLE INSTALLATIONS, AND THE NEW INTERSECTION ACROSS FROM STATE FARM BOULEVARD. SOILS: �„ THE SUBJECT SITE IS LOCATED WITHIN THE PIEDMONT PHYSIOGRAPHIC PROVINCE OF VIRGINIA. THE SOILS IN THE PIEDMONT PROVINCE ARE HIGHLY VARIABLE ALTHOUGH COMMONLY FOUND TO BE SHALLOW WITH CLAYEY SUBSOILS. PIEDMONT SOILS ARE LOW IN PHOSPHORUS. SOME AREAS WITHIN THE PIEDMONT CONTAIN SOILS DERIVED FROM MICA SCHIST WHICH ARE HIGHLY ERODIBLE. CRITICAL AREAS: CRITICAL AREAS CONSIST OF DEEP EXCAVATIONS, AND AREAS REQUIRING FILL OF 2' OR MORE. THE ENTIRE SITE (GIVE OR TAKE) FALLS WITHIN ONE OF THESE DESCRIBED CRITICAL AREAS AS MOST OF THE SITE WILL BE FILLED. FILL DEPTHS ARE EXPECTED TO EXCEED 5' IN CERTAIN AREAS. EROSION AND SEDIMENT CONTROLS WILL BE INSTALLED AND MAINTAINED TO ENSURE DOWN-GRADE PROPERTIES AND RECEIVING STORM SEWER SYSTEMS WILL NOT BE OVERTAXED WITH CONSTRUCTION LADEN SEDIMENT. WHENEVER SEDIMENT-LADEN WATER IS REMOVED FROM A CONSTRUCTION SITE BY MEANS OF PUMPING, A TEMPORARY SETTLING & FILTERING DEVICE SHALL BE USED TO FILTER THE .• SEDIMENT-LADEN WATER PRIOR TO THE WATER BEING DISCHARGED OFF-SITE. STEEP SLOPES (AT NO UN PROPOSED LUXOR ROAD EXTENSION, AND AT THE PROPOSED DRIVE THRU - PRIOR TO RETAINING WALL CONSTRUCTION) SHALL BE PROTECTED AS NECESSARY. MANAGEMENT STRATEGIES: A PORTION OF THE POST-DEVELOPED RUNOFF WILL BE CAPTURED BY A FILTERRA BIORETENTION STRUCTURE (ONE 6x12 FILTERRA UNIT) WHICH WILL EFFECTIVELY PROVIDE THE NECESSARY POLLUTANT REMOVAL EFFICIENCIES NECESSARY TO ENSURE POST-DEVELOPED POLLUTANT LOADS LEAVING THE SITE WILL NOT EXCEED THE ESTIMATED PRE-DEVELOPED POLLUTANT LOADS). FOR WATER QUANTITY, THE MAJORITY OF POST-DEVELOPED RUNOFF WILL BE CAPTURED AND CONVEYED TO AN UNDERGROUND DETENTION SYSTEM CONSISTING OF OVERSIZED PIPES. AN OUTLET CONTROL STRUCTURE FEATURING A WEIR WALL WITH A CIRCULAR ORIFICE AND A RECTANGULAR ORIFICE ACTS TO ENSURE CAPTURED RUNOFF IS RELEASED AT OR BELOW THE DETERMINED PRE-DEVELOPED FLOW RATES. ALL PROPOSED STORM INLETS AND APPLICABLE EXISTING STORM INLETS WILL BE PROTECTED BY EROSION AND SEDIMENT CONTROL MEASURES AT ALL TIMES THROUGHOUT CONSTRUCTION. EROSION AND SEDIMENT CONTROL MEASURES: 3.02 CONSTRUCTION ENTRANCE A CONSTRUCTION ENTRANCE WILL BE LOCATED AT AN EXISTING ENTRANCE TO THE SITE OFF PANTOPS DRIVE. 3.05 SILT FENCE SILT FENCE WILL BE PLACED SUCH THAT THE TOTAL CONTRIBUTING DRAIN AREA WILL NOT EXCEED 1/4 AC. PER 100 LF. THE SILT FENCE IS TO BE INSTALLED BEFORE ANY AREA IS DISTURBED AND REMOVED AFTER PERMANENT STABILIZATION IS ACHIEVED. 3.07 INLET PROTECTION INLET PROTECTION SHALL BE INSTALLED TO PREVENT SEDIMENT FROM ENTERING STORM DRAIN r STRUCTURES PRIOR TO PERMANENT STABILIZATION OF THE DISTURBED AREA. 3.09 TEMPORARY DIVERSION DIKES DIVERSION DIKES SHALL BE INCORPORATED TO ENSURE SHEET FLOW IS CONVEYED TO A TEMPORARY SLOPE DRAIN TO ENSURE UNSTABILIZED SLOPES ARE NOT OVER BURDENED DURING CONSTRUCTION OPERATIONS. 3.13 TEMPORARY SEDIMENT TRAPS TEMPORARY SEDIMENT TRAPS WILL BE CONSTRUCTED TO ENSURE ADJACENT PROPERTIES ARE ADEQUATELY PROTECTED. 3.31 AND 3.32 TEMPORARY AND PERMANENT STABILIZATION AREAS NOT OTHERWISE STABILIZED BY IMPERVIOUS GROUNDCOVER, LANDSCAPING, OR MULCH WILL BE PERMANENTLY SEEDED. DURING CONSTRUCTION, TEMPORARY SEEDING WILL BE APPLIED TO DENUDED AREAS AS NECESSARY. TEMPORARY AND PERMANENT SEEDING SHALL BE APPLIED AS SPECIFIED IN TABLES 3.31-B AND 3.32-D FOUND IN DCR'S ESC TECHNICAL BULLETIN #4 AND IN ACCORDANCE TO ALBEMARLE COUNTY STANDARDS. 3.35 MULCHING MULCHING WILL BE USED TO PROTECT THE SOIL SURFACE FROM RAINDROP IMPACT AND REDUCING THE VELOCITY OF OVERLAND FLOW. MULCH WILL ALSO FOSTER GROWTH OF THE VEGETATION BY INCREASING AVAILABLE MOISTURE AND PROVIDING INSULATION AGAINST EXTREME HEAT AND COLD. THE CHOICE OF MULCHING MATERIAL WILL BE BASED ON THE TYPE OF SOIL TO BE PROTECTED, SITE CONDITIONS, SEASON, ECONOMICS AND THE OWNER PREFERENCE MAINTENANCE: SILT FENCE MAINTENANCE: SILT FENCES SHALL BE INSPECTED IMMEDIATELY AFTER EACH RAINFALL AND AT LEAST DAILY. DURING PROLONGED RAINFALL ANY REQUIRED REPAIRS SHALL BE MADE IMMEDIATELY. CLOSE ATTENTION SHALL BE PAID TO THE REPAIR OF DAMAGED SILT FENCE RESULTING FROM END RUNS AND UNDER CUTTING. SHOULD THE FABRIC ON A SILT FENCE DECOMPOSE OR BECOME INEFFECTIVE PRIOR TO THE END OF THE EXPECTED USABLE LIFE AND THE BARRIER STILL BE NECESSARY, THE FABRIC SHALL BE REPLACED PROMPTLY. SEDIMENT DEPOSITS SHOULD BE REMOVED AFTER EACH STORM EVENT. SEDIMENT MUST BE REMOVED WHEN DEPOSITS REACH APPROXIMATELY ONE-HALF THE HEIGHT OF THE BARRIER. ANY SEDIMENT DEPOSITS REMAINING IN PLACE AFTER THE SILT FENCE IS NO LONGER REQUIRED SHALL BE DRESSED TO CONFORM TO THE EXISTING GRADE, PREPARED AND SEEDED. GENERAL MAINTENANCE: ALL OTHER TEMPORARY AND PERMANENT EROSION & SEDIMENT CONTROLS SHALL BE MAINTAINED IN ACCORDANCE TO MIN. STANDARDS AND SPECIFICATIONS OUTLINED IN THE VIRGINIA EROSION AND SEDIMENT CONTROL HANDBOOK. 2.2 Temporary Sediment Trap Calculations - NORTON & DODD, P.C. PROJECT: CHICK FIL A SURVEYORS.ENGINEERS&PLANNERS COUNTY: ALBEMARLE CO.,VIRGINIA (757)487-4535 JOB NUMBER: 22100 300 George Washington Highway North DATE: 10.31.2014 +8• CHESAPEAKE VIRGINIA ' PREPARED BY: MAD SILT TRAP GEOMETERY SUMMARY TABLE: rr SEDIMENT DRAIN REQ'D VOL VOL.PROVIDED C Ho H L W TRAP AREA "WET"&"DRY" "WET" "DRY" ID (AC) (CY) (CY) (CY) (FT) (FT) (FT) (FT) (FT) 1 0.91 60.97 74.37 68.81 3 1.5 2.5 5.5 2.5 "` VOLUME ESTIMATES: METHOD: CONIC FORMULA: V=d((Al+[sq rt(Al*A2)]+A2)/3) V=Incremental Volume,A1=Area @1,A2=Area @2,d=change in elevation btwn 1&2. •• WET STORAGE ELEVATION H 1 CONTOUR AREA INCREMENTAL VOLUME TOTAL VOLUME TOTAL VOLUME [STAGE] moo (FT) (FT) (SF) (CF) (CF) (CY) 524.00 0.00 360.00 0.00 1 0.00 0.00 524.50 0.50 446.00 201.12 201.12 7.45 _ 525.00 _ 1.00 544.00 247.09 448.21 16.60 'a. 526.00 2.00 781.00 658.94 1107.15 41.01 527.00 3.00 1026.00 900.72 2007.87 74.37 TOTAL WET STORAGE= 2007.87 74.37 REQUIRED WET STORAGE.' 60.97 ( WET STORAGE PROVIDED=I 74.37 10K .r DRY STORAGE ELEVATION H CONTOUR AREA INCREMENTAL VOLUME TOTAL VOLUME TOTAL VOLUME [STAGE] or (FT) (FT) (SF) (CF) (CF) (CY) 527.00 0.00 1031.00 0.00 0.00 0.00 527.50 0.50 1168.00 549.39 549.39 20.35 ®r 528.00 1.00 1309.00 618.92 1168.31 43.27 52.8.5.0 1.50 1450.00 689.45 1857.76 68.81 TOTAL WET STORAGE 1857.76 68.81 REQUIRED DRY STORAGE=I 60.97 DRY STORAGE PROVIDED= 68.81 OK NMI r•A Ai Div kSkSh D Kf LENGTH(IN FEET) :`r.. f S x DRAIN AREA(IN AC.) wo .----CLASS I RIYRAP PLAN VIEW j`- ' �`_--�__ -" - l.«i• ,Pa...-,':I. may- r TABLE COARSE AGGRC0ATE '} _ _ (VDOT 43,4357 OR 115) ' -- ------- •I-f` ;Ho: w. __ 15 0.5 2.0 ___EXCAVATED 'FIL.TE3 CLOTr1 _ ---• NM 3.0 1.0 2.0 ARE A 2.5 1.S 2.5 3.0 2.0 2.5 OU[LEI (PERSPEC I IVE VIEW) 3.S 2.S 3.0 4.0 3.0 3.0 ■• 4.S 3.', 40 .0 4.0 4,5 Lhr' i 1~I rt.,l DRY 51.7kA:i: + y s., Y i ., 1--, OriICINA- ',B.' - ,-,:-W �17 jb G/CJ.YD.rACkE ,,-r, -� - I OR.GINAL C;12C1i;N() - / GROUND 4b'E1 SIOHA(2t CLASSI A, 6/C.J.Y_.1%ACIi_ '.0 j RIP SI ,EXCAVATED; h A;_G-EGAI t \ =:LTCR CLOT'- MIN CROSS SECTION A-A (THROUGH OUTLET) - PROJECT: CHICK-FIL-A NORTON GI DODD, P.C. COUNTY: ALBEMARLE CO.,VIRGINIA SURVEYORS.ENGINEERS&PLANNERS (757)487.4535 JOB NUMBER: 22100 300 George Washington Highway North DATE: 10.31.2014 +M CHESAPEAKE VIRGINIA I PREPARED BY: JMD SILT TRAP GEOMETERY SUMMARY TABLE: SEDIMENT DRAIN REQ'D VOL VOL.PROVIDED *.• C Ho H L W TRAP AREA "WET"&"DRY" "WET" "DRY" ID (AC) (CY) (CY) (CY) (FT) (FT) (FT) (FT) (FT) 2 1.35 90.45 114.56 92.19 3.5 1.5 2.5 8.1 2.5 "" VOLUME ESTIMATES: METHOD: CONIC FORMULA: V=d((Al+[sq rt(Al*A2)]+A2)/3) V=Incremental Volume,A1=Area @1,A2=Area @2,d=change in elevation btwn 1&2. %.. WET STORAGE ELEVATION H CONTOUR AREA INCREMENTAL VOLUME TOTAL VOLUME TOTAL VOLUME [STAGE] ' (FT) (FT) (SF) (CF) (CF) ' (CY) - 527.50 1 0.00 415.00 0.00 0.00 0.00 528.00 0.50 520,00 233.26 233.26 8.64 529.00 1.50 785.00 647.97 881.23 32.64 MO 530.00 2.50 1110.00 942.82 1824.05 67.56 5.31.00 3.50 1435.00 1269.03 3093.07 114.56 I TOTAL WET STORAGE= 3093.07 114.56 REQUIRED WET STORAGE=I 90.45 I WET STORAGE PROVIDED=I 114.56 10K ON DRY STORAGE ELEVATION H CONTOUR AREA INCREMENTAL VOLUME TOTAL VOLUME TOTAL VOLUME [STAGE] "" (FT) (FT) (SF) (CF) (CF) (CY) 531.00 0.00 1435.00 0.00 0.00 0.00 531.50 0.50 1605.00 759.60 759.60 28.13 .rte 532.00 1.00 1710.00 828.61 1588.21 58.82 _ 532.50 1.50 1895.00 900.85 2489.07 92.19 TOTAL WET STORAGE 2489.07 92.19 REQUIRED DRY STORAGE.' 90.45 DRY STORAGE PROVIDED=I 92.19 OK wr TA I A T � DIV'RYON I)Kf `LENGTH (IN FEET] - �� /A.__._ t S x DHAiN AR=A(IN AC.) CLASS I RIPgAP PLAN VIEW --,4{�,,y'.y : =;, -�"_--- (ABLE COARSE AGGRE rATE'--- -''. - -- (VDOT 03,'i357 OR Its) -- - f ,: "Ho; ;l^d; •1.5 0.5 2.0 -- EXCAVATED FILTE3 CLOTH ___�_ "" 2.0 1.0 2.0 A■iI A 2.5 I.0 z.5 2 3.0 2.0 OU I LEI (PERSPEC I IA VIEW) 3.5 2.5 3.0 4.0 3.0 3.0 rr 4.5 3.5 4.0 IV'/: 5 0 4.0 u.5 r 11 :;+iv SIORAL; f y.s:,-.:;4t',. 1-7 '.f . 'O%iIGINA_ B' _ - "at' '' I-' Ii (tla; ORIGINAL RC)IIND :qi,:;;f;ii"cr;1- ',- - T GROUND L E _V. r ELEV. ----,_1� :. b1•'E I SI ORAL`-E CLASS I A• 6/CJ.YJ./ACR'_ '.C 7 ;t CL RIP RAP (EXCAVATED) .. - COA-Si -4- A:=C-�:EGAIE ' - . . LTER CLOTF .r CROSS SECTION A-A (THROUGH OUTLET) ,r. 3.0 Stormwater Quality 3.1 Stormwater Quality Narrative Performance Based Water Quality Calculations were performed in accordance to the Virginia Division of Conservation and Recreation's Stormwater Management Handbook. Calculations conclude that the relative pollutant removal requirement for the site is 0.25 pounds per year. A Filterra Biroretention Structure has been specified to meet this requirement. ,r. WO ASO MOP Ail MI Wr 3.2 Performance Based Water Quality Calculations ^IN VIRGINIA DEPARTMENT OF CONSERVATION AND RECREATION PERFORMANCE-BASED WATER QUALITY CALCULATIONS STEP 1-Determine the applicable area(A)and the post-developed impervious cover(Ipo„). Applicable area(A)*= 2.56 ac 111,450|sf Post-developed impervious cover: ALL= 1.46 ac | 63'400sf TOTAL= 1.46 ac e3,400 |post~(total post-developed impervious cover/A)xzO0~ 571% 4111111 *The area subject to the criteria may vary from locality tn locality.Themfone,consultthebco|ityforpmper determination of this value. STEP z-Determine the average land cover condition<�m,�^�)o,�heexis�inaimponjous�ove,(�**�>. Average land cover condition(Iwatershed): tem If the locality has determined land cover for individual watersheds within its jurisdiction,use the watershed specific value determined by the locality as|=w°mm• terw |=m��= 161% (Otherwise,usethe[hesapeakeeaydefaubva|vp��m,°heu=16%j Existing impervious cover(|�m'�>- Determine the existing impervious cover of the development site if pres m. WINO Existing impervious cover: ALL= 1.50 ac | 65,289|sf TOTAL= 1.50 ac 65,289 =" 'existing |ex|g1nQimpem�uscover/A^*>xlOO~ 59i% **This area should be the same as used in STEP 1. • = = AIM STEP 3-Determine the appropriate development situation. The site information determined in STEP 1 and STEP 2 provide enough information to determine the °r` appropriate development situation under which the performance criteria will apply. Situation 1: This consists of land development where the existing percent impervious cover(lesisting)is less than or equal to 4.• the average land cover condition(Iwatershed)and the proposed improvements will create a total percent impervious cover ('post)which is less than or equal to the average land cover condition(Iwatershed)• AM 'post I 571 <_ 'watershed 1 16; FALSE Situation 2: This consists of land development where the existing percent impervious cover(lexisdng)is less than or equal to "` the average land cover condition(Iwatershed)and the proposed improvements will create a total percent impervious cover ('post)which is greater than the average land cover condition(Iwatershed)• AM 1 I 1 ' 161 FALSE FALSE 'existing 591 <_ 'watershed I J 'post 1 57 > 'watershed i 16; TRUE WY Situation 3: This consists of land development where the existing percent impervious cover(Iexisting)is greater than the average land cover condition(Iwatershed)• MO 'existing i 59j > 'watershed s 16; TRUE Situation 4: This consists of land development where the existing percent impervious cover('existing)is served by an existing .i, stormwater management BMP(s)that adresses water. If the proposed development meets the criteria for development Situation 1,than the low density development is considered to be the BMP ..0 and no pollutant removal is required.The calculation procedure for Situation 1 stops here.If the proposed development meets the criteria for development Sitatuations 2,3,or 4,then proceed to STEP 4 on the appropriate worksheet. "O SITUATION 3 STEP 4-Determine the relative pre-development pollutant load(Lpfe). um 1-pre(existing)= relative pre-development total phosphorous load(pounds per year) 'existing= existing site impervious cover(percent expressed in whole numbers) MIS A= applicable area(acres) 1-pre(existing)= [0.05+(0.009 X lexistwng))X A X 2.28 f 1 41110 Lpre(existing)= i L r 3.371pounds per year 1-pre(watershed)= relative pre-development total phosphorous load considering average landcover condition for watershed (pounds per year) 'watershed= average land cover condition for specific watershed or locality or the Chesapeake Bay default value of 16% (percent expressed in whole numbers) vr. A= applicable area(acres) 1-pre(watershed)= [0.05+(0.009 X'watershed)]X A x 2.28 Lpre(watershed)= 1 1.13: pounds pounds per year MIN MIN r.. STEP 5-Determine the relative post-development pollutant load IL Lpo5t1 Lpost= relative post-development total phosphorous load(pounds per year) !post= post-developed percent impervious cover(percent expressed in whole numbers) Lpost= [0.05+(0.009 x Ipost)]X A x 2.28 I MEI 1 3.28i pounds per year STEP 6-Determine the relative pollutant removal requirement(RR). RR= Lpost-(0.9 X Lpre(existing)) RR= l. 0.25i pounds per year WO Lpost-Lpre(watershed) RR= 2.15ipounds per year IMO The pollutant removal requirement(RR)for Situation 3 is the lesser of the two values calculated above: RR= I 0.251pounds per year r STEP 7-Identify best management practice(BMP)for the site. 1.Determine the required pollutant removal efficiency for the site: IMO EFF= (RR/Lpost)x 100 EFF= I 81% r. 2.Select BMP(s)from Table 5-15 and locate on the site: BMP1 FILTERRA BIORETENTION(STR.Fl) MEI BMP2 BMP3 YIN 3.Determine the pollutant load entering the proposed BMP(s): LBMp= relative post-development total phosphorous load entering the proposed BMP(pounds per year) Oa IBMp= post-development percent impervious cover of BMP drainage area(percent expressed in whole numbers) A= drainage area of proposed BMP(acres) I BMP1= I 501% impervious area= 10,8601SF ABMP1= i 0.50;acres I 21,617;SF IMO IBMP2= 01% impervious area= O;SF ABMP2= I 0.00;acres 1 OISF <rr (BMP3= I 01% impervious area= I O;SF . r ABMP3= 0.00:acres O:SF — LBMP= [0.05+(0.009 x IBMP)]x A x 2.28 LBMps= I 0.57;pounds per year ""` LBMP2= 1 0.00;pounds per year LBMP3= I 0.00;pounds per year r • a 411` 4.Calculate the pollutant loan removed by the proposed BMP(s): Lremoved= post-development pollutant load removed by proposed BMP(pounds per year) EFFBMP= pollutant removal efficiency of BMP(expressed in decimal form) EFFBMPI= 1 65%1 r � +r/ E FBMP2= i i EFFBmp3 i Lremoved= EFFBMP X Lemp r i Lremoved(BMP1)= ( 0.371 pounds per year Lremoved(8MP2)= 0.00I pounds per year r � Lremoved(BMP3)= 0.00Ipounds per year +YUi 5.Calculate the total pollutant load removed by the BMP(S): removed/total= 1 0.37;pounds per year 6.Verify compliance: +r removed/total>=RR 0.36931 >= 0.2477; TRUE +rr .r. AIM AIM IMO 0110 4.0 Stormwater Quantity .. 4.1 Stormwater Quantity Narrative In order to meet Albemarle County's Stormwater Management Standards specific to Stormwater Quantity, the stormwater management facility (SWMF) is designed to meet, at a minimum, the 0. following criteria: a. The 1, 2, 5 and 10-year post-developed peak discharges from the site shall not exceed the 1, 2, 5 and 10-year pre-developed peak discharges. "` b. The proposed conveyance systems shall capacitate the 10-year storm. Computer applications developed specifically for Urban Hydrosystems Engineering were used to .. expedite the design of the proposed stormwater management facility. Hydraflow Hydrographs Extension for AutoCAD Civil 3D Rel. 2008 by Autodesk, Inc. (v6.052) was used to develop detailed . models of detention systems and analysis of individual drainage basins. Hydraflow Storm Sewers Extension for AutoCAD Civil 3D Rel. 2008 by Autodesk, Inc. (v6.052) was used for hydrologic and hydraulic analysis of storm sewer conveyance networks. The Soil Conservation Service (SCS) now known as The National Resources Conservation Service (NRCS), hydrologic methods was used for the analysis of individual watersheds. The SCS method is OW used to determine peak discharge at various storm frequencies. Hydraflow Hydrographs Extension computes SCS Method runoff hydrographs by convoluting a rainfall hyetograph —in this case, the 24 hour type II design storm -through a unit hydrograph. Convolution is known as linear superpositioning, and means that each ordinate of the rainfall hyetograph is multiplied by each ordinate of the unit hydrograph, thus creating a series of smaller hydrographs. These hydrographs are then summed to N, form the final runoff hydrograph. The rational method was also incorporated in development of the storm sewer conveyance system models. As stated previously, the storm water management facility must be designed to ensure that the 1, 2, 5, and 10-year post-developed peak discharges from the area of interest shall not exceed the 1, 2, 5 and 10-year pre-developed peak discharges (Criterion 'a'). The area of interest (AOI) was determined '"' considering the limits of disturbance and proposed area of the parcel once a Boundary Line Adjustment Plat has been finalized. The pre-developed unit hydrograph was constructed considering the following watershed characteristics and geologic factors: . Area (Area of Interest—AOI) = 2.56 Acres. Composite Curve Number (Composite CN) = 82 Time of Concentration Tc = 10 minutes. The Composite Curve Number computations can be found in section 4.1.1 of this report. - Hydrograph No. 1, which is the final SCS runoff hydrograph representing the area of interest pre- developed, can be found in section 4.1.2 of this report. The drainage area maps are part of the WPO plans submitted to the County. Initial analyses of pre- vs. post- developed conditions indicate that a detention facility would have to be incorporated into the design. A piped detention system is proposed. To ensure adequacy of the proposed detention facility, and knowing that only portions of the area of interest would be conveyed to the detention facility, allowable peak discharge rates for the 1, 2, 5, and 10-year events were . developed. The allowable peak discharge rate is simply the pre-developed discharge less any bypass runoff(runoff generated by areas within the AOI not captured by the BMP) plus any runoff created from areas outside the AOI captured by the detention facility. The post-developed drainage area map .. delineates these areas. Note, only a small area beyond the area of interest is captured by the detention facility. The resulting runoff is considered negligible, so no credit was considered in development of the allowable peak discharge rates. i The final SCS runoff hydrograph representing the bypass watershed is Hydrograph No. 2 (section 4.1.2) results from the various runoff hydrographs and the resulting post-developed runoff allowed to . discharge from the proposed detention facility are further explained and summarized on the worksheet entitled "ALLOWABLE PEAK DEVELOPED RUNOFF DETERMINATION" which is included at the . end of this narrative. Hydrograph 3, which was developed to determine peak runoff for the area captured by the BMP, .. can be found in section 4.1.2 as well. Hydrograph 3 is routed through the proposed detention facility. The reports summarizing characteristics of the detention facility and results of the routing results are reported in Section 4.2. The aforementioned worksheet (ALLOWABLE PEAK DEVELOPED RUNOFF "' DETERMINATION") summarizes this information and includes an adequacy check of the proposed system proving that the proposed detention facility adequately meets (exceeds) criterion a. Criterion 'b', the proposed conveyance system shall capacitate the 10-year storm. As indicated on the associated storm sewer tabulation reports (Section 4.3), criteria b is fulfilled. The receiving system is further analyzed to ensure adequacy. A storm sewer conveyance . system model was developed representing the pipe network that receives runoff from the site. The representative report is also included in section 4.3. .. HORTON & DODD, RC. PROJECT: CHICK-FIL-A SURVEYORS, ENGINEERS&PLANNERS COUNTY: ALBEMARLE CO.,VIRGINIA ter (757)487-4535 JOB NUMBER: 22100 300 George Washington Highway North DATE: 11.03.2014 .__T______ CHESAPEAKE VIRGINIA PREPARED BY: JMD ALLOWABLE PEAK DEVELOPED RUNOFF DETERMINATION two 1. DETERMINE MAXIMUM PEAK DEVELOPED RUNOFF ALLOWED. QMAX.DEV=QPRE Where QMAX.DEV= MAXIMUM POST-DEVELOPED PEAK RUNOFF ALLOWED FOR ENTIRE AREA OF INTEREST(AOI) QPRE=PEAK PRE-DEVELOPED RUNOFF FOR ENTIRE AOI "' 2. DETERMINE PEAK RUNOFF ALLOWED TO DISCHARGE FROM SWMF. QSWMF.ALLOW=QMAX.DEV-QBYPASS+QCREDIT — Where QSWMF.ALLOW=PEAK RUNOFF ALLOWED TO DISCHARGED FROM SWMF. QBYPASS=POST-DEV.RUNOFF FROM AREA WITHIN AOI THAT BYPASSES THE SWMF "" QCREDIT= POST-DEV. RUNOFF FROM AREAS BEYOND AOI CAPTURED BY SWMF QPRE QMAX.DEV QBYPASS QCREDIT QSWMF.ALLOW= or A.R.I. (CFS) (CFS) (CFS) (CFS) (CFS) 1 5.537 5.537 2.134 0.000 3.403 2 7.557 7.557 3.062 0.000 4.495 "' 5 10.530 10.530 4.500 0.000 6.030 10 13.560 13.560 5.999 0.000 7.561 ®" 3. VERIFY COMPLIANCE. IF QSWMF.ACTUAL<1=QSWMF.ALLOW THEN SWMF IS ADEQUATE. ow Where QSWMF.ACTUAL= PEAK RUNOFF DISCHARGED FROM SWMF(SEE HYDROGRAPH 4 REPORTS). WA QSWMF.ALLOW= QSWMF.ACTUAL= ADEQUACY A.R.I. (CFS) (CFS) CHECK 1 3.403 1.910 OK ..,. 2 4.495 2.796 OK 5 6.030 3.719 OK 10 7.561 7.265 OK ow oar moo raw 4.1.1 Composite CN and Weighted C Determinations _-_---_- HORTON & DODD, P.C. � PROJECT: CHICK-FIL-A SURVEYORS, ENGINEERS&PLANNERS COUNTY: ALBEMARLE CO.,VIRGINIA (757)4874535 JOB NUMBER: 22100 '- IFICI 300 George Washington Highway North DATE: 11.03.2014 CHESAPEAKE VIRGINIA PREPARED BY: JMD me COMPOSITE CURVE NUMBER AND WEIGHTED GROUNDCOVER COEFFICIENT DETERMINATIONS PRE-DEVELOPED CwTp AND CNwTD: ... (S.F.) (Acres) HSG CN C CONSERVED OPEN SPACE 5,855 0.13 B 55.00 0.20 MANAGED TURF: 40,306 0.93 B 61.00 0.35 ...• IMPERVIOUS: 65,289 1.50 B 98.00 0.90 Total Area: 111,450 2.56 ow CNwTD: 82 Cwro: 0.66 moo POST DEVELOPED CWTD AND CND(FOR ENTIRE AREA OF INTEREST): (S.F.) (Acres) HSG CN C CONSERVED OPEN SPACE 5,855 0.13 B 55.00 0.20 MANAGED TURF: 42,195 0.97 B 61.00 0.35 IMPERVIOUS: 63,400 1.46 B 98.00 0.90 ... Total Area: 111,450 2.56 CNw1O: 82 ow CwTp: 0.65 POST DEVELOPED CwTD AND CNwTO(FOR AREA CAPTURED BY SWMF): (S.F.) (Acres) HSG CN C CONSERVED OPEN SPACE 4,743 0.11 B 55.00 0.20 ""' MANAGED TURF: 13,133 0.30 B 61.00 0.35 IMPERVIOUS: 42,191 0.97 B 98.00 0.90 Total Area: 60,067 1.38 CNwrD: 87 CwTp: 0.72 POST DEVELOPED Cm-D AND CNwTD(FOR AREA BYPASSING SWMF): "4" (S.F.) (Acres) HSG CN C CONSERVED OPEN SPACE 1,112 0.03 B 55.00 0.20 MANAGED TURF: 29,062 0.67 B 61.00 0.35 .r IMPERVIOUS: 21,209 0.49 B 98.00 0.90 Total Area: 51,383 1.18 ... CNwrp: 76 CwTp: 0.57 Am t.. 4.1.2 SCS Runoff Hydrographs 1 Hydrograph Report Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2008 by Autodesk, Inc.v6.052 Wednesday,Dec 3,2014 - Hyd. No. 1 PRE-DEV.SITE Hydrograph type = SCS Runoff Peak discharge = 5.537 cfs Storm frequency = 1 yrs Time to peak = 720 min Time interval = 3 min Hyd. volume = 15,044 cuft - Drainage area = 2.560 ac Curve number = 82 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = USER Time of conc. (Tc) = 10.00 min - Total precip. = 3.30 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 PRE-DEV.SITE - Q (cfs) Q (cfs) Hyd. No. 1 -- 1 Year 6.00 6.00 mug, 5.00 5.00 4.00 4.00 3.00 - 3.00 "" 2.00 — 2.00 - 1.00 - — 1.00 0.00 - ---- 0.00 0 180 360 540 720 900 1080 1260 1440 1620 Time (min) Hyd No. 1 2 Hydrograph Report Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2008 by Autodesk, Inc.v6.052 Wednesday, Dec 3,2014 Hyd. No. 1 PRE-DEV.SITE Hydrograph type = SCS Runoff Peak discharge = 7.557 cfs Storm frequency = 2 yrs Time to peak = 720 min Time interval = 3 min Hyd. volume = 20,472 cuft Drainage area = 2.560 ac Curve number = 82 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = USER Time of conc. (Tc) = 10.00 min Total precip. = 4.00 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 PRE-DEV.SITE Q (cfs) Hyd. No. 1 --2 Year Q (cfs) 8.00 8.00 6.00 - - - 6.00 N. tow • 4.00 - - - - - 4.00 - 2.00 - - - - 2.00 _.. , .......,, 0 180 360 540 720 900 1080 1260 1440 1620 Hyd No. 1 Time (min) 3 Hydrograph Report Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2008 by Autodesk, Inc.v6.052 Wednesday, Dec 3,2014 • Hyd. No. 1 PRE-DEV.SITE Hydrograph type = SCS Runoff Peak discharge = 10.53 cfs Storm frequency = 5 yrs Time to peak = 720 min Time interval = 3 min Hyd. volume = 28,613 cuft Drainage area = 2.560 ac Curve number = 82 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = USER Time of conc. (Tc) = 10.00 min Total precip. = 5.00 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 PRE-DEV.SITE • Q (cfs) Q (cfs) Hyd. No. 1 -- 5 Year 12.00 12.00 - 10.00 - •- 10.00 I zi 8.00 - — 8.00 6.00 - - 6.00 4.00 - - - — 4.00 2.00 - - - - - 2.00 0.00 Ls r......a........,_.. ,. 0.00 Aro 0 180 360 540 720 900 1080 1260 1440 1620 Hyd No. 1 Time (min) 4 Hydrograph Report Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2008 by Autodesk, Inc.v6.052 Wednesday,Dec 3,2014 - Hyd. No. 1 PRE-DEV.SITE - Hydrograph type = SCS Runoff Peak discharge = 13.56 cfs Storm frequency = 10 yrs Time to peak = 720 min Time interval = 3 min Hyd. volume = 37,051 cuft - Drainage area = 2.560 ac Curve number = 82 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = USER Time of conc. (Tc) = 10.00 min - Total precip. = 6.00 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 PRE-DEV.SITE Q (cfs) Q (cfs) Hyd. No. 1 -- 10 Year 14.00 I 14.00 • 12.00 - - - - 12.00 �. 10.00 - - - - - - - 10.00 '�. 8.00 " — 8.00 • 6.00 - - - - 6.00 4.00 - 4.00 2.00 - - - - - - - 2.00 0.00 0 180 360 540 720 900 1080 1260 1440 1620 Hyd No. 1 Time (min) 1 Hydrograph Report Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2008 by Autodesk, Inc.v6.052 Wednesday, Dec 3,2014 - Hyd. No. 2 POST-DEV.BYPASS - Hydrograph type = SCS Runoff Peak discharge = 2.134 cfs Storm frequency = 1 yrs Time to peak = 722 min Time interval = 2 min Hyd. volume = 5,627 cuft Drainage area = 1.230 ac Curve number = 76 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = USER Time of conc. (Tc) = 10.00 min - Total precip. = 3.30 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 POST-DEV.BYPASS - Q (cfs) Q (cfs) Hyd. No. 2 -- 1 Year 3.00 3.00 2.00 2.00 *" 1.00 1.00 a a 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 Time (min) Hyd No. 2 a 2 Hydrograph Report Hydraflow Hydrographs Extension for AutoCADO Civil 3D®2008 by Autodesk, Inc.v6.052 Wednesday,Dec 3,2014 Hyd. No. 2 POST-DEV.BYPASS Hydrograph type = SCS Runoff Peak discharge = 3.062 cfs Storm frequency = 2 yrs Time to peak = 720 min Time interval = 2 min Hyd. volume = 8,005 cuft Drainage area = 1.230 ac Curve number = 76 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = USER Time of conc. (Tc) = 10.00 min Total precip. = 4.00 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 POST-DEV.BYPASS 4.1 Q (cfs) Q (cfs) Hyd. No. 2 --2 Year 4.00 4.00 3.00 , 3.00 40. • 2.00 • 2.00 1.00 1.00 , ... 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 Time(min) - - — Hyd No. 2 3 Hydrograph Report Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2008 by Autodesk, Inc.v6.052 Wednesday,Dec 3,2014 Hyd. No. 2 POST-DEV.BYPASS Hydrograph type = SCS Runoff Peak discharge = 4.500 cfs Storm frequency = 5 yrs Time to peak = 720 min Time interval = 2 min Hyd. volume = 11,675 cuft Drainage area = 1.230 ac Curve number = 76 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = USER Time of conc. (Tc) = 10.00 min Total precip. = 5.00 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 POST-DEV.BYPASS Q (cfs) Q (cfs) Hyd. No. 2 --5 Year 5.00 5.00 w.• ww. 4.00 4.00 -;! 3.00 3.00 bow 2.00 , 2.00 1.00 1.00 — - 1 - 0.00 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 Time (min) Hyd No. 2 4 Hydrograph Report Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2008 by Autodesk, Inc.v6.052 Wednesday,Dec 3,2014 41g Hyd. No. 2 POST-DEV.BYPASS Hydrograph type = SCS Runoff Peak discharge = 5.999 cfs Storm frequency = 10 yrs Time to peak = 720 min Time interval = 2 min Hyd. volume = 15,563 cuft Drainage area = 1.230 ac Curve number = 76 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = USER Time of conc. (Tc) = 10.00 min Total precip. = 6.00 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 POST-DEV.BYPASS Q (cfs) Q (cfs) Hyd. No. 2 -- 10 Year 6.00 6.00 5.00 5.00 4.00 4.00 3.00 3.00 a 2.00 2.00 a 1.00 1.00 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 Time (min) Hyd No. 2 1 Hydrograph Report Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2008 by Autodesk, Inc.v6.052 Wednesday, Dec 3,2014 saw Hyd. No. 3 POST-DEV.TO SWMF Hydrograph type = SCS Runoff Peak discharge = 4.390 cfs Storm frequency = 1 yrs Time to peak = 719 min Time interval = 1 min Hyd. volume = 10,037 cuft Drainage area = 1.380 ac Curve number = 87 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = USER Time of conc. (Tc) = 10.00 min Total precip. = 3.30 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 POST-DEV.TO SWMF Q (cfs) Hyd. No. 3 -- 1 Year Q (cfs) 5.00 5.00 .. 4.00 4.00 • .. 3.00 3.00 2.00 2.00 1.00 1.00 .. 0.00 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 Hyd No. 3 Time (min) 2 Hydrograph Report Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2008 by Autodesk, Inc.v6.052 Wednesday,Dec 3,2014 - Hyd. No. 3 POST-DEV.TO SWMF Hydrograph type = SCS Runoff Peak discharge = 5.717 cfs Storm frequency = 2 yrs Time to peak = 719 min Time interval = 1 min Hyd. volume = 13,208 cuft Drainage area = 1.380 ac Curve number = 87 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = USER Time of conc. (Tc) = 10.00 min Total precip. = 4.00 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 POST-DEV.TO SWMF - Q (cfs) Q (cfs) Hyd. No. 3 --2 Year 6.00 6.00 °Ill 5.00 5.00 4.00 - - 4.00 4.0 3.00 3.00 - 2.00 2.00 1.00 - - 1.00 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 Time (min) Hyd No. 3 3 Hydrograph Report Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2008 by Autodesk, Inc.v6.052 Wednesday, Dec 3,2014 - Hyd. No. 3 POST-DEV.TO SWMF Hydrograph type = SCS Runoff Peak discharge = 7.623 cfs Storm frequency = 5 yrs Time to peak = 719 min Time interval = 1 min Hyd. volume = 17,870 cult - Drainage area = 1.380 ac Curve number = 87 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = USER Time of conc. (Tc) = 10.00 min " Total precip. = 5.00 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 POST-DEV.TO SWMF a•• Q (cfs) Hyd. No. 3 -- 5 Year Q (cfs) 8.00 8.00 • 6.00 . — 6.00 4.00 - - 4.00 2.00 - 2.00 0.00 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 Hyd No. 3 Time (min) a 4 Hydrograph Report Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2008 by Autodesk, Inc.v6.052 Wednesday,Dec 3,2014 Hyd. No. 3 POST-DEV.TO SWMF Hydrograph type = SCS Runoff Peak discharge = 9.527 cfs Storm frequency = 10 yrs Time to peak = 719 min Time interval = 1 min Hyd. volume = 22,629 cuft Drainage area = 1.380 ac Curve number = 87 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = USER Time of conc. (Tc) = 10.00 min Total precip. = 6.00 in Distribution = Type II Storm duration = 24 his Shape factor = 484 POST-DEV.TO SWMF Q (cfs) Q (cfs) Hyd. No. 3 -- 10 Year 10.00 10.00 8.00 - 8.00 6.00 6.00 4.00 - 4.00 2.00 - 2.00 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 Time (min) - Hyd No. 3 5 Hydrograph Report Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2008 by Autodesk, Inc.v6.052 Wednesday,Dec 3,2014 " Hyd. No. 3 POST-DEV.TO SWMF - Hydrograph type = SCS Runoff Peak discharge = 11 .42 cfs Storm frequency = 25 yrs Time to peak = 719 min Time interval = 1 min Hyd. volume = 27,448 cuft - Drainage area = 1.380 ac Curve number = 87 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = USER Time of conc. (Tc) = 10.00 min - Total precip. = 7.00 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 POST-DEV.TO SWMF - Q (cfs) Hyd. No. 3 --25 Year Q (cfs) 12.00 12.00 a 10.00 - - Yi - 10.00 • 8.00 - - - - 8.00 6.00 - - - - - 6.00 a"" 4.00 - - - - 4.00 ..r 2.00 - - — - — 2.00 a 0 120 240 360 480 600 720 840 960 1080 1200 1320 Hyd No. 3 Time (min) 6 Hydrograph Report Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2008 by Autodesk, Inc.v6.052 Wednesday,Dec 3,2014 - Hyd. No. 3 POST-DEV.TO SWMF - Hydrograph type = SCS Runoff Peak discharge = 13.31 cfs Storm frequency = 50 yrs Time to peak = 719 min Time interval = 1 min Hyd. volume = 32,309 cuft - Drainage area = 1.380 ac Curve number = 87 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = USER Time of conc. (Tc) = 10.00 min Total precip. = 8.00 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 POST-DEV.TO SWMF - Q (cfs) Q (cfs) Hyd. No. 3 -- 50 Year 14.00 14.00 12.00 12.00 10.00 10.00 8.00 8.00 6.00 H 6.00 4.00 4.00 2.00 2.00 0.00 0 120 240 360 480 600 720 840 960 1080 1200 1320 Time (min) • Hyd No. 3 7 Hydrograph Report Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2008 by Autodesk, Inc.v6.052 Wednesday,Dec 3,2014 Hyd. No. 3 POST-DEV.TO SWMF - Hydrograph type = SCS Runoff Peak discharge = 14.25 cfs Storm frequency = 100 yrs Time to peak = 719 min Time interval = 1 min Hyd. volume = 34,751 cuft - Drainage area = 1.380 ac Curve number = 87 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = USER Time of conc. (Tc) = 10.00 min - Total precip. = 8.50 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 POST-DEV.TO SWMF -M. Q (cfs) Hyd. No. 3-- 100 Year Q (cfs) 15.00 I 15.00 12.00 - - - 12.00 r4 9.00 - - 9.00 6.00 - - 6.00 - 3.00 - - - — - - 3.00 o.00 0 120 240 360 480 600 720 840 960 1080 1200 1320 Hyd No. 3 Time (min) 4.2 Reservoir (Routing) Hydrographs Pond Report Hydraflow Hydrographs Extension for AutoCADO Civil 3D®2008 by Autodesk, Inc.v6.052 Wednesday,Dec 3,2014 Pond No. 1 - SWMF_pipe storage ® Pond Data UG Chambers-Invert elev.=533.30 ft, Rise x Span=4.00 x 4.00 ft, Barrel Len=218.00 ft, No. Barrels=2, Slope=0.25%, Headers=Yes Stage/Storage Table . Stage(ft) Elevation(ft) Contour area(sqft) Incr.Storage(cuft) Total storage(cuft) 0.00 533.30 n/a 0 0 .., 0.45 533.75 n/a 125 125 0.91 534.21 n/a 475 599 1.36 534.66 n/a 673 1,273 1.82 535.12 n/a 775 2,048 2.27 535.57 n/a 819 2,867 "" 2.73 536.03 n/a 819 3,686 3.18 536.48 n/a 774 4,460 3.64 536.94 n/a 674 5,133 4.09 537.39 n/a 474 5,607 two 4.55 537.85 n/a 124 5,731 Culvert/Orifice Structures Weir Structures r. [A] [B] [C] [PrfRsr] [A] [B] [C] [D] Rise(in) = 18.00 6.00 5.00 0.00 Crest Len(ft) = 20.00 5.00 0.00 0.00 Span(in) = 18.00 6.00 12.00 0.00 Crest El.(ft) = 541.95 536.75 0.00 0.00 ,., No.Barrels = 1 1 1 0 Weir Coeff. = 3.33 3.33 3.33 3.33 Invert El.(ft) = 533.20 533.25 535.10 0.00 Weir Type = Riser Rect --- --- Length(ft) = 148.00 0.00 0.00 0.00 Multi-Stage = Yes Yes No No Slope(%) = 0.88 0.00 0.00 n/a °rr N-Value = .013 .012 .013 n/a Orifice Coeff. = 0.60 0.60 0.60 0.60 Exfil.(in/hr) = 0.000(by Wet area) Multi-Stage = n/a Yes Yes No TW Elev.(ft) = 0.00 NM Note Culvert/Orifice outflows are analyzed under inlet(lc)and outlet(oc)control Weir risers checked for orifice conditions pc)and submergence(s) vita Stage(ft) Stage/Storage Elev(ft) 5.00 538.30 ,.• 1 4.00 , rp, 537.30 „r 'I Me 3.00 536.30 2.00 535.30 srr m 1.00 1.; 534.30 0.00 533.30 •® 0 600 1,200 1,800 2,400 3,000 3,600 4,200 4,800 5,400 6,000 Storage Storage(cuft) w. Pond Report Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2008 by Autodesk, Inc.v6.052 Wednesday,Dec 3,2014 Pond No. 1 - SWMF_pipe storage IMO Pond Data UG Chambers-Invert elev.=533.30 ft, Rise x Span=4.00 x 4.00 ft, Barrel Len=218.00 ft, No. Barrels=2, Slope=0.25%, Headers=Yes NMI Stage/Storage Table Stage(ft) Elevation(ft) Contour area(sqft) Incr.Storage(cuft) Total storage(cuft) 0.00 533.30 n/a 0 0 ,,,r, 0.45 533.75 n/a 125 125 0.91 534.21 n/a 475 599 1.36 534.66 n/a 673 1,273 1.82 535.12 n/a 775 2,048 2.27 535.57 n/a 819 2,867 *1110 2.73 536.03 n/a 819 3,686 3.18 536.48 n/a 774 4,460 3.64 536.94 n/a 674 5,133 4.09 537.39 n/a 474 5,607 ..r 4.55 537.85 n/a 124 5,731 Culvert/Orifice Structures Weir Structures ,®, [A] [B] [C] [PrfRsr] [A] [B] [C] [D] Rise(in) = 18.00 6.00 5.00 0.00 Crest Len(ft) = 20.00 5.00 0.00 0.00 Span(in) = 18.00 6.00 12.00 0.00 Crest El.(ft) = 541.95 536.75 0.00 0.00 No.Barrels = 1 1 1 0 Weir Coeff. = 3.33 3.33 3.33 3.33 Invert El.(ft) = 533.20 533.25 535.10 0.00 Weir Type = Riser Rect --- --- Length(ft) = 148.00 0.00 0.00 0.00 Multi-Stage = Yes Yes No No Slope(%) = 0.88 0.00 0.00 n/a mop N-Value = .013 .012 .013 n/a Orifice Coeff. = 0.60 0.60 0.60 0.60 Exfil.(in/hr) = 0.000(by Wet area) Multi-Stage = n/a Yes Yes No TW Elev.(ft) = 0.00 MO Note CulverUOrifice outflows are analyzed under inlet(lc)and outlet(oc)control Weir risers checked for orifice conditions(lc)and submergence(s) aa. Stage(ft) Stage/Discharge Elev(ft) 5.00 538.30 4.00 537.30 AIN - 3.00 536.30 2.00 535.30 we 1.00 534.30 ... 0.00 533.30 gm 0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 Total Q Discharge(cfs) Pond Report a. Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2008 by Autodesk, Inc.v6.052 Wednesday, Dec 3,2014 Pond No. 1 - SWMF_pipe storage - Pond Data UG Chambers-Invert elev. =533.30 ft, Rise x Span=4.00 x 4.00 ft, Barrel Len=218.00 ft, No. Barrels=2, Slope=0.25%, Headers=Yes .. Stage/Storage Table Stage(ft) Elevation(ft) Contour area(sqft) Incr.Storage(cuft) Total storage(cuft) 0.00 533.30 n/a 0 0 ..r 0.45 533.75 n/a 125 125 0.91 534.21 n/a 475 599 1.36 534.66 n/a 673 1,273 1.82 535.12 n/a 775 2,048 2.27 535.57 n/a 819 2,867 e111' 2.73 536.03 n/a 819 3,686 3.18 536.48 n/a 774 4,460 3.64 536.94 n/a 674 5,133 4.09 537.39 n/a 474 5,607 .,. 4.55 537.85 n/a 124 5,731 Culvert/Orifice Structures Weir Structures [A] [B] [C] [PrfRsr] [A] [B] [C] [D] Rise(in) = 18.00 6.00 5.00 0.00 Crest Len(ft) = 20.00 5.00 0.00 0.00 Span(in) = 18.00 6.00 12.00 0.00 Crest El.(ft) = 541.95 536.75 0.00 0.00 a.. No.Barrels = 1 1 1 0 Weir Coeff. = 3.33 3.33 3.33 3.33 Invert El.(ft) = 533.20 533.25 535.10 0.00 Weir Type = Riser Rect --- --- Length(ft) = 148.00 0.00 0.00 0.00 Multi-Stage = Yes Yes No No Slope(%) = 0.88 0.00 0.00 n/a `-' N-Value = .013 .012 .013 n/a Orifice Coeff. = 0.60 0.60 0.60 0.60 Exfil.(in/hr) = 0.000(by Wet area) Multi-Stage = n/a Yes Yes No TW Elev.(ft) = 0.00 ®r Note'Culvert/Orifice outflows are analyzed under inlet(ic)and outlet(oc)control Weir risers checked for orifice conditions(ic)and submergence(s). Stage/Storage/Discharge Table Stage Storage Elevation Clv A Clv B Clv C PrfRsr Wr A Wr B Wr C Wr D Exfil User Total ,w ft cuft ft cfs cfs cfs cfs cfs cfs cfs cfs cfs cfs cfs 0.00 0 533.30 0.00 0.00 0.00 --- 0.00 0.00 --- --- --- --- 0.000 0.45 125 533.75 0.49 ic 0.48 is 0.00 --- 0.00 0.00 --- --- --- --- 0.477 0.91 599 534.21 0.76 is 0.75 is 0.00 --- 0.00 0.00 --- --- --- --- 0.751 ... 1.36 1,273 534.66 0.97 ic 0.96 ic 0.00 --- 0.00 0.00 --- --- --- --- 0.961 1.82 2,048 535.12 1.16 ic 1.14 ic 0.01 ic --- 0.00 0.00 --- --- --- --- 1.144 2.27 2,867 535.57 2.30 is 1.23 is 1.03 is --- 0.00 0.00 --- --- --- --- 2.257 2.73 3,686 536.03 3.04 ic 1.34 ic 1.70 ic --- 0.00 0.00 --- --- --- --- 3.041 3.18 4,460 536.48 3.64 ic 1.46 is 2.17 is --- 0.00 0.00 --- --- --- --- 3.631 ..• 3.64 5,133 536.94 5.43 is 1.52 is 2.56 ic --- 0.00 1.34 --- --- --- --- 5.412 4.09 5,607 537.39 11.70 oc 1.01 is 2.15 is --- 0.00 8.53 --- --- --- --- 11.70 4.55 5,731 537.85 14.19 oc 0.49 is 1.04 is --- 0.00 12.66 s --- --- --- --- 14.19 .r Allit MO MO a.r ... Hydrograph Report 1 Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2008 by Autodesk, Inc.v6.052 Wednesday,Dec 3,2014 Hyd. No. 4 SWMF ROUTING Hydrograph type = Reservoir Peak discharge = 1.910 cfs Storm frequency = 1 yrs Time to peak = 727 min Time interval = 1 min Hyd. volume = 10,036 cuft Inflow hyd. No. = 3 - POST-DEV.TO SWMF Max. Elevation = 535.45 ft Reservoir name = SWMF_pipe storage Max. Storage = 2,646 cuft tes Storage Indication method used. air SWMF ROUTING Q (cfs) Q (cfs) Hyd. No. 4 1 Year 5.00 5.00 4.00 4.00 . 3.00 3.00 2.00 2.00 1.00 1.00 0.00 i.. - 1- 1. 0.00 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 Time (min) Hyd No. 4 -- Hyd No. 3 Total storage used = 2,646 cuft 2 Hydrograph Report Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2008 by Autodesk, Inc.v6.052 Wednesday,Dec 3,2014 Hyd. No. 4 SWMF ROUTING Hydrograph type = Reservoir Peak discharge = 2.796 cfs Storm frequency = 2 yrs Time to peak = 726 min Time interval = 1 min Hyd. volume = 13,208 cuft Inflow hyd. No. = 3 - POST-DEV.TO SWMF Max. Elevation = 535.87 ft Reservoir name = SWMF_pipe storage Max. Storage = 3,395 cuft Storage Indication method used. 40. SWMF ROUTING 1M. Q (cfs) Q (cfs) Hyd. No. 4--2 Year 6.00 6.00 gen 5.00 5.00 4.00 4.00 3.00 3.00 2.00 2.00 1.00 1.00 — a 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 Time (min) Hyd No. 4 Hyd No. 3 Total storage used = 3,395 cuft a 3 - Hydrograph Report Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2008 by Autodesk, Inc.v6.052 Wednesday,Dec 3,2014 - Hyd. No. 4 SWMF ROUTING Hydrograph type = Reservoir Peak discharge = 3.719 cfs Storm frequency = 5 yrs Time to peak = 726 min Time interval = 1 min Hyd. volume = 17,870 cuft Inflow hyd. No. = 3 - POST-DEV.TO SWMF Max. Elevation = 536.56 ft Reservoir name = SWMF_pipe storage Max. Storage = 4,573 cuft Storage Indication method used. ,.r SWMF ROUTING 4" Q (cfs) Hyd. No. 4 --5 Year Q (cfs) 8.00 8.00 6.00 6.00 4.00 4.00 2.00 2.00 - 0.00 i -�..,.,, .. 0.00 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 Time (min) -- Hyd No. 4 Hyd No. 3 Total storage used = 4,573 cuft - Hydrograph Report 4 Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2008 by Autodesk, Inc.v6.052 Wednesday,Dec 3,2014 - Hyd. No. 4 SWMF ROUTING Hydrograph type = Reservoir Peak discharge = 7.265 cfs Storm frequency = 10 yrs Time to peak = 723 min Time interval = 1 min Hyd. volume = 22,628 cuft Inflow hyd. No. = 3 - POST-DEV.TO SWMF Max. Elevation = 537.08 ft Reservoir name = SWMF_pipe storage Max. Storage = 5,281 cuft Storage Indication method used. wr SWMF ROUTING Q (cfs) Q (cfs) Hyd. No. 4 -- 10 Year 10.00 10.00 8.00 8.00 - 6.00 6.00 4.00 4.00 2.00 2.00 0.00 ... �., 0.00 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 Time (min) Hyd No. 4 Hyd No. 3 Total storage used = 5,281 cuft 5 Hydrograph Report Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2008 by Autodesk, Inc.v6.052 Wednesday,Dec 3,2014 - Hyd. No. 4 SWMF ROUTING Hydrograph type = Reservoir Peak discharge = 10.44 cfs Storm frequency = 25 yrs Time to peak = 721 min Time interval = 1 min Hyd. volume = 27,448 cuft Inflow hyd. No. = 3 - POST-DEV.TO SWMF Max. Elevation = 537.30 ft Reservoir name = SWMF_pipe storage Max. Storage = 5,505 cuft Storage Indication method used. ,rr +rr SWMF ROUTING - Q (cfs) Hyd. No. 4 --25 Year Q (cfs) 12.00 12.00 �• 10.00 10.00 8.00 8.00 6.00 6.00 - 4.00 4.00 2.00 - 2.00 0.00 . ...... _. -. .. .,..-.._: _ .._.,... ..-.. . 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 Time (min) - Hyd No. 4 Hyd No. 3 Total storage used = 5,505 cuft 6 Hydrograph Report Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2008 by Autodesk, Inc.v6.052 Wednesday,Dec 3,2014 - Hyd. No. 4 SWMF ROUTING Hydrograph type = Reservoir Peak discharge = 13.14 cfs Storm frequency = 50 yrs Time to peak = 720 min Time interval = 1 min Hyd. volume = 32,309 cuft Inflow hyd. No. = 3 - POST-DEV.TO SWMF Max. Elevation = 537.55 ft Reservoir name = SWMF_pipe storage Max. Storage = 5,648 cuft Storage Indication method used. SWMF ROUTING - Q (cfs) Q (cfs) Hyd. No. 4 -- 50 Year 14.00 14.00 12.00 12.00 - 10.00 10.00 - 8.00 8.00 6.00 6.00 4.00 4.00 2.00 2.00 „_ - 0.00 0 120 240 360 480 600 720 840 960 1080 1200 1320 Time (min) - Hyd No. 4 Hyd No. 3 Total storage used = 5,648 cuft de, 7 Hydrograph Report Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2008 by Autodesk, Inc.v6.052 Wednesday, Dec 3,2014 Hyd. No. 4 SWMF ROUTING Hydrograph type = Reservoir Peak discharge = 13.92 cfs Storm frequency = 100 yrs Time to peak = 720 min Time interval = 1 min Hyd. volume = 34,751 cuft Inflow hyd. No. = 3 - POST-DEV.TO SWMF Max. Elevation = 537.76 ft Reservoir name = SWMF_pipe storage Max. Storage = 5,705 cuft Storage Indication method used. SWMF ROUTING Q (cfs) Hyd. No. 4 -- 100 Year Q (cfs) 15.00 15.00 12.00 12.00 9.00 9.00 6.00 6.00 • 3.00 - 3.00 0.00 — .._, — 0.00 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 Time (min) Hyd No. 4 Hyd No. 3 Total storage used = 5,705 cuft 4.3 Storm Sewer Design Calculations o.. 4.3.1 Post Developed Tc Calculations r- _ NORTON & DODD, P.C. SURVEYORS.ENGINEERS&PLANNERS PROJECT: CHICK-FIL-A Fiihl (757)487-4535 COUNTY: ALBEMARLE CO., VIRGINIA 300 George Washington Highway North JOB NUMBER: 22100 CHESAPEAKE VIRGINIA DATE: 11.29.2014 PREPARED BY: JMD . POST-DEVELOPED TIME OF CONCENTRATION CALCULATIONS: TO STRUCTURE D7: m• Tc-Overland Flow(Seelye) Tc-Channel Flow(Kirpich) Tc-TOTAL L S C Tc H L Tc Tc- Tc- TOTAL (length (slope in rational TIME OF (height in ' (length in TIME OF CONCENTRATION Overland Channel(in: (in min.) in ft) ft/ft) runoff CONCENTRATION ft) ft) =0.00948*H^(- `"" ) ) ) )=0.225*E^(0.42)*SA(- 0.38)*LA(1.13) (in min.) min.) coef. I .19)*C^(-1) 50 0.022 0.35 6.86 15 655 5.16 6.86 5.16 12 a.. 1 0 0.00 1 0: 0.00 1 0 0.00 .• 'TOTAL= r 6.86 TOTAL= 5.16 TO STRUCTURE D5 am Tc-Overland Flow(Seelye) Tc-Channel Flow(Kirpich) Tc-TOTAL L S C Tc H L Tc Tc- Tc- TOTAL (length (slope in I rational TIME OF (height in (length in TIME OF CONCENTRATION Overland Channel(in (in min.) ,.. in ft) ft/ft) runoff CONCENTRATION ft) ft) =0.00948*HA(- (in min.) min.) coef. =0.225*L^(0.42)*S^(- 0.38)*L^(1.13) .19)*c^(4) .io 126 0.0476' 0.351 8.74 1 0 0.00 27.38 0.00 27 54 0.037 0.35 6.42 1 0 0.00 521 0.0192 0.35 7.16 1 0 0.00 32 0.041 0.35 5.06 1 0 0.00 1 0 0.00 TOTAL= 27.38 TOTAL= 0.00 " TO STRUCTURE 010 =SYSTEM FLOW TIME(FROM STORM SEWER TABULATION RPT. FOR D5-D1)=27.2 MIN. 4111111 4.3.2 Storm Sewer Tabulation Reports rn o m o 0 a) in C N J m w N ‘— N AMP Q o m N CO 0 O. _ C O `o W o •— 3 to o N m +rr E2 m co 0 _ "a c 4 c E a o U) cK ..... co W co -J itrr I C c(0 a V N CO L0 0 ii AND > n$ ui c co W in — o t N to CI — M co Z O o NI- OM a. 'a ' N C W . in ar _ M N M N X 0 a_ N. II A. 16 y W v-, _o n_ TD 00 4..c• i . . II H w N• C_ U 16 r.--. U ce C N c Y N o ` Ws u) — o V ~ y C o II .r C _ o N o. U 11 -a- E al ci 15 cC AM O d Q 0 v r- co "FJ C ci o co MID= 0 ai U c j:2 ce U o + CU 4) Ti v C E ci a)W Z c A3+ 0 = C 0 co U cfl Am r W W d• J co .II CO F M Q CC � �O C c W m J L c Igo L o J W a Cn O . ,^ 4mto N c u.. 0 tu �♦ J 0 Z UM Hydrograph Report Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2008 by Autodesk, Inc.v6.052 Thursday, Dec 4,2014 Hyd. No. 5 TO STR. Fl Hydrograph type = Rational Peak discharge = 2.305 cfs Storm frequency = 10 yrs Time to peak = 10 min Time interval = 1 min Hyd. volume = 1,452 cuft Drainage area = 0.500 ac Runoff coeff. = 0.76 Intensity = 6.066 in/hr Tc by User = 7.00 min IDF Curve = VA_Albemarle.IDF Asc/Rec limb fact = 1.5/1.5 TO STR. Fl Q (cfs) Q (cfs) Hyd. No. 5 -- 10 Year 3.00 3.00 2.00 - - - 2.00 1.00 - - - - 1.00 0.00 - _- - 0.00 0 2 4 6 8 10 12 14 16 18 20 22 Hyd No. 5 Time (min) CD N 0) 0 CO ow° O c 0 N c C J CO w N N V a`) a O a3 vim ) N co > O O E o a.lJ =. N V E Lo o err ii ii. co Co 0 x _ c p a (� L..4-c) rY MN cD Q N = M W co J WO 0 2 C _ (0 a N- M LO 0 was ' a O ., N of — M - C W 'n t o N- a v M 7 LC) Z a) a O _, o 0 0 +^ a CD _N C W <.,Z V) O. .t, d W 0)) ... > O X O -_2 II N L ._y t O '\0w. v a N oO `-. N- .,. I I v a) C U _ II CL v C a0 il.� 0 LL7 Ane co I CO C ° l°r 0 C c o U co o o co co of .ii + _ a) o N N Q >- L 0) H a c N 0 co ° 0 co ++O 0 c w v I I CO J M it▪ >' • C E O2 _ m c irL CHJ o W J a u)O `}^� C la1 O C ♦ J <— U Z um Hydrograph Report Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2008 by Autodesk, Inc.v6.052 Thursday, Dec 4,2014 " Hyd. No. 6 ROOF DRAINAGE Hydrograph type = Rational Peak discharge = 0.660 cfs Storm frequency = 10 yrs Time to peak = 8 min Time interval = 1 min Hyd. volume = 297 cuft Drainage area = 0.110 ac Runoff coeff. = 0.9 Intensity = 6.666 in/hr Tc by User = 5.00 min IDF Curve = VA_Albemarle.IDF Asc/Rec limb fact = 1.5/1.5 ROOF DRAINAGE ANN Q (cfs) Hyd. No. 6 -- 10 Year Q (cfs) 1.00 1.00 0.90 0.90 0.80 0.80 ®" 0.70 0.70 0.60 0.60 0.50 0.50 0.40 0.40 0.30 0.30 0.20 0.20 0.10 0.10 0.00 - 0.00 '"` 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Hyd No. 6 Time (min) 41 N cv a) R 0 a > +.. 0 _ O C C _ N J 0 0 w N M �} m MIS V O N N CO a>i a r` 0 O E uJ m ° to E to a NMI E2 -o _ o to 0 = 1` c p co a 0 t7 to co tt WM M a 1- N w LO to J aY•/ I C co (co 0 - Co M M co tO to ^ N AY Q. O N to N M M C (JJ to to O t > co V co CO O to to Z CD _ C.Q c CMO CCO O . 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PROJECT: CFA-PANTOPS SURVEYORS. ENGINEERS Si PLANNERS COUNTY: CHARLOTTESVILLE,VA (757)487-4535 300 George Washington Highway North JOB NUMBER: 22100 CHESAPEAKE VIRGINIA DATE: 12.01.2014 PREPARED BY: JMD VINO n= 0.013 *CAPACITY OBTAINED FROM STORM SEWER TABULATION REPORTS ..r FROM POINT TO POINT SLOPE DIA *CAPACITY CROSS SECTIONAL DESIGN VELOCITY AREA OF PIPE (ft/ft) (in) (cfs) (ft2) (ft/5) .Nr Al B1 0.0043 18 6.87 1.77 3.89 A2 B4 0.01 18 10.50 1.77 5.94 C3 C2 0.0088 18 9.83 1.77 5.56 — C2 Cl 0.0088 18 9.86 1.77 5.58 MID MIN era ONNr eNN err IMP INSERT A. VOW g MINIP WOO *NO ONO 1111011 VIM NEP 41/110 MIN AIM AIM 411111