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HomeMy WebLinkAboutWPO202300019 Calculations 2023-03-21SHIMP ENGINEERING, P.C. Design Focused Engineering March 14, 2023 Engineering Review Albemarle County Department of Community Development 401 McIntire Road Charlottesville, VA 22902 Regarding: WP02022-00XXX 5" Street Self Storage Stormwatl Dear Reviewer, The purpose of this project is to construct a self-service storage facility. The total area of disturbance is 1.28 acres. This development is an amendment to the approved common plan of development, 5" Street Commercial Development - WP0201600082. The common plan of development includes an approved stormwater plan for the development of this site. This calculation packet also references SDP201900045 which is the site plan amendment for Phase 1 of this development. Water Quantity: Water quantity is addressed by meeting channel protection requirements in 9VAC25-870- 66.13.1.a and 134.a and flood protection requirements in 9VAC35-870-66.C.2.a and C.3.a. Per the approved stormwater management plan in WP0201600082, the proposed development outfalls into an existing channel that was armored as shown in the calculation packet approved on'9/l/17. The calculations show that the channel is nonerosive during the 2-yr design storm and that its banks are not overtopped during the 10-yr design storm. The adequate channel outfalls directly into Moore's Creek, where the site area is less than 1% of the contributing watershed. STORMWATER MANAGEMENT NARRATIVE: OVERVIEW: THE PROPOSED PLAN PROVIDES STORM WATERTREATMENT FOR THE FUTURE DEVELOPMENT OF THISPARCHI THE PROPOSED PLAN COMPLIES W rrl l PAlt'I' 11B REQUI RLMENTS. STO RM W ATER Q UANTII'Y: CHANNEL PROTECTION IS METTHROUGH9VAC25-870-66, SUBSECTIONS B. La AND BA.a. FLOOD PROTECTION IS MET THROUGH 9 VAC25-870-66, SU9SEJ_TIONS C.2.a AND C.3.a. THE PROPOSED DEVELOPMENTOUTFALJ-S INTO AN EXISTING CHANNEL THEPROPOSEDPIAN ARMORS THE EXLSTWGCHANNW- CALCULATIONS HAVE BEEN PROVIDED THAT SHOW THE CHANNEL IS NONEROSIVE DURING THE 2-YEAR DESIGN STORM AND D'S BANKS ARE NOT OVERTOPPED DURING'I'HE 10-YEAR DESIGN STORM. THE ADEQUATE CI IANNM ANALYZED OI.rrF'AILS DIRECTLY INTO MOORES CREEK, WHERE THE SITE % AREA IS LESS THAN I% OFTHE STREAM': CONI RIBUTRIIG WATERSHED. SEE THIS PLAN, ANDTH6 ACCOMPANYING STOPAIWATER MANAGEMENT CALL'LILA'IIONS PACKET, FOR DETAILS. Image 1: SII AI Narrative approved in IFP0201600082 This site is part of DA A & B as indicated in WPO201600082 which is 3.25 ac. Of this area, 2.41 ac is designated as impervious cover. Please reference the drainage area map and site cover calculations below. FROM APPR04ED PLAN j WPO 201600082 � r ,.y. .x c i •loll ' �y i.fw Vrt]�I qr ♦ i W ApuliM / giyym . .•Y. 1Mdtl .R Y6 II1W M. COVE' CN y Image 2: WP0201600082 Drainage area map and land cover calculations. x I v I omi / It The first phase of development, approved in SDP201900045, contributed 1.62 ac of impervious cover within DA A & B. Please reference the drainage area map and site cover calculations below. �mr,q.o run—meuwgpuwnwy.nnawwa u.a la[m)I V.W.. I. 1.b1..1. 1_. PU I. OW I 4{etNgn Cp.Fr CRlun i9 B RVMw p" (xmRreeea ) wi RVoe„pex(wmerzlud'r ) iolal4rca �acrcf�: 3.2$ xo�on xmon,o� volume h'' 0 Image 3: SDP201900045 Drainage area map and land cover calculations. This development, shown as Phase 2 in SDP201900045, proposes 0.89 ac of impervious area which exceeds the 0.79 ac remaining in DA A & B from the approved stormwater management plan (2.41 ac — 1.62 ac = 0.79 ac). The flow rate was recalculated considering the 0.10 ac increase in impervious area (0.89 ac proposed — 0.79 ac designed = 0.10 ac) and a 0.10 ac increase in total drainage area (3.25 ac + 0.10 ac = 3.35 ac). Please reference the drainage map below which compares the original drainage area in WP020160082 to the proposed area in this development. All new impervious area is directed to the original outfall point. . . _ POST. �{ r' YIYI•�A V1M� gfIX� �MR.YM4Y W Y Zi � � \\_ v INLRR09m YIM1lL[YMRj IUINIML[V6C! r - / - YPNPIY65 MID5�6.IIE%MMILLL .Iwmnar nx.rn,.rrNenwN.mouwon !/�� _ a! � -,>jr �L��; � �^' rye, �y .. +uoN.In.¢nS4'r - �ouunr.un..R Rlou.orNm.xRw. i y: .•' , ).rM45TnYRrv1Yw91T pRrllUflpN r�u.rn rwii .OLINViL.14OIW.V P MRMILQIOMIUNIVWPR�B W.M IM IY � / �yY� r ' � 4 p. RX MMLNff.IMM1�KWM NI•M t M•1[OM6'MPILCOVIVMl•FR TMYMII.N / 4 F I iyt /may 'V �'�x .�r�v� i PAYilb Vll.Q.NMI - • a8•Y l CI Ru. rql COWIIIICR V10.1� ,� ` 'rr AS- 'L 1 H VOURS CIRK• .•�oMC. I M �•LIWII \ JYIYlI tlf 9. 9W. 4 ................ � 1 •dr ,•REVISED DA A & B TOTAL AREA = 3.35 AC � .: o ff IMPERVIOUS AREA — 2.51 AC '_-�Oe, / - F'HOPUSED r - BUILDING LAVOUT r 44 "v """0""^• `R" - - _ ADDITIONAL IMPERVIOUS •m.. iad im.N enw mo. axur wi AREA=0.10AC awl 'aA 1. ra. uw Image 4: Proposed increase to Drainage Area A & B. WATERSHED SUMMARY Pr Development Post -Development 2yearFlow, 10.yearFlow, 2-year Flow, SO -year CN Area, at ds crs LN Area, ac. cfs Flow, ch DA W 66.5 2.11 2.84 6.79 DA'3' 56.2 L14 0.55 2.12 88.3 3.2-5 12.54 21.56 DA'C - - - - 57.7 O.D9 0.05 0.is DA'D' 792 4.11 9.15 18.10 Total - 21.75 39.94 Image 5: WPO201600082 Pre and Post -Development Watershed Summary. The 2-yr design storm flow rate was recalculated with the increase in impervious area and determined to be 13.16 cfs, 0.62 cfs higher than originally calculated for DA A & B (please reference the TR-55 calculations included in this packet). In order to determine if the increase in impervious area still meets channel protection requirements, the armored channel was modeled in hydraulic toolbox with the increased flow rate. The 2-yr storm velocity is 6.78 fps, which is 0.05 fps greater than previously calculated. Based on the riprap calculations in WP0201600082, the change in velocity is minor and the channel remains nonerosive, complying with 9VAC25- 870-66.B.1.a. The 10-yr design storm flow rate was recalculated to be 22.46 cfs, 0.96 cfs higher than originally calculated for DA A & B. The new 10-yr design storm depth is 1.31', 0.01' higher than the original 10-yr storm depth. Below is a cross section of the channel with the 10-yr storm water surface elevation, demonstrating that the channel contains the 10-yr storm which complies with 9VAC25-870-66.C2.a. 0 w Cross Section Stabon (R) Image 6., Hydraulic Toolbox cross section of armored channel with revised IO yr design storm flow rate. Water Quality: Water quality compliance was achieved through the dedication of open space and the purchase of nutrient credits as part of WPO201600082. STORMWATER QUALM. THE STORMWATER QUAUTYTREATMENTFORTHE FUTURE DEVELOPMENT IS PROVIDED VIA THE IMPLEMENTATION OF TWO BEST MANAGEMENT PRACTICES. THE BEST MANAGEMENT PRACTICE OF PROTECTING FOREST @ OPEN SPACES FROM DISTURBANCES IS UTIL2 ED. A PROPOSED S WM FOREST AND OPEN SPACE EASEMENT WIfLBERECORDED WITH THIS DEVELOPMENTS PLAT. AFTERTHE USE OF THIS BMP A FINAL PHOSPHOROUS REMO VALOF 2.49 Ibstyr. IS REQUIRED. PHOSPHOROUS REMOVAL CREDITS HAVE BEEN PURCHASED FORTHIS REMAINING BALANCE, ACHIEMG COMPLIANCE WITH PART KB WATER QUAUTYREQUIREMEMIS. PLEASE SEETHE ATTACHED STORMWATER MANAGEMENT CALCULATIONS PACKET FOR ADDITIONAL DETAILS. Image 7: SWMNarrative approved in WPO201600082 In order to offset the additional 0.10 ac of impervious area, 0.18 lbs/yr of phosphorous removal is required. This will be achieved with the purchase of nutrient credits. Please reference the VRRM spreadsheet included in this calculation packet. If you have any questions regarding the information included in this stormwater management calculation packet, please contact Shimp Engineering at 434-227-5140 or by email at chris(a)shimp-engineering com. Best Regards, Chris Marshall, EIT Shimp Engineering, P.0 Contents: Post -Development Stormwater Management Calculations: Post -Development TR-55 Calculation LD-204 Stormwater Inlet Computations LD-229 Storm Drain Design Computations Stormwater Quality Calculations: VRRM New Development Compliance Spreadsheet Independent Reports: Approved DA Map & Stormwater Calculation Packet — WPO201600082 Approved Phase 1 DA Map & Stormwater Calculations — SDP201900045 Post -Development Stormwater Management Calculations: Post -Development TR-55 Calculation LD-204 Stormwater Inlet Computations LD-229 Storm Drain Design Computations Project Location Worksheet 4: 5th Street Landing Self -Storage Albemarle County, VA Checkone: ❑ Present X❑ Developed 1. Data Peak Discharge method BY Shimp Engineering, PC Shimp Engineering, PC Date 01/30/23 Date 01/30/23 Drainage area .......................................... Am = 0.0052 mi2 (acres/640) Runoff curve number.................................CN = 89 (From worksheet 2) Time of concentration ................................. Tc = 0.10 hr (From worksheet 3) Rainfall distribution ....................................... = II (I, IA, II III) Pond and swamp areas sprea throughout watershed ................................... = 0 percent of Am ( 0 acres or mi2 covered) 2. Frequency ............. 3. Rainfall, P (24-hour) ...................... yr ...................... in Storm #1 Storm #2 Storm #3 2 10 3.69 5.57 4. Initial abstraction, I in 0.247 0.247 (Use CN with table 4-1) 5. Compute la/P.................................................................................. 0.067 0.044 6. Unit peak discharge, qu........................................................ csm/in 1,000 1,000 (Use Tc and la/ P with exhibit 4— ) 7. Runoff, Q..................................... (From worksheet 2) Figure 2-6 8. Pond and swamp adjustment factor, Fp ............. (Use percent pond and swamp area with table 4-2. Factor is 1.0 for zero percent pond ans swamp area.) 9. Peak discharge, qp............................................. ( Where qp = qu An, QFp ) in 2.53 4.32 .. 1.0 1.0 ......... ft3/s 13.16 22.46 D-4 (210-VI-TR-55, Second Ed., June 1956) 5th Street Self Storage LD-204 Stormwater Inlet Computations Inlets on Grade Only Sag Inlets Only uc y a o E > w m y n E _o m X x (� a g w m o i s E m - n '"-' v m U H > A u L' w m a V ? i a v t`n i 0 ci a rc 0 3 rn 1 2 3 4 1 5 6 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 (ft) (so(ac) (iNhr)('f) Cr) (It) 01) (cfs) (cfs) (ft) (It) (ft) A3 DI-36 6 6,881 0.16 0.90 0.14 5.2 0.74 0.74 0.015 0.02 0.03 0.01 0.104 0.5 0.208 5.197 6.2 0.88 0.88 0.015 0.117 0.5 0.234 5.834 Al DI-36 6 5,780 0.13 0.90 0.12 5.2 0.62 0.62 0.015 0.02 0.03 0.01 0.092 0.5 0.184 4.619 6.2 0.74 0.74 0.015 0.104 0.5 0.208 5.197 61 DI-313 6 3,240 0.07 0.90 0.07 5.2 0.35 0.35 0.015 0.02 0.06 0.01 0.063 0.5 0.126 3.155 6.2 0.41 0.41 0.015 0.07 0.5 0.14 3.506 LD-229 Storm Drain Design Computations From Sinxtuie To Simcture Catch. Area ac Runoff C., Increment AC Accum. AC Total TOC min 10-yr Inlemity in/hr 10-yr Flow cis Up Inve6 Elev. Down Imert Elev. pipe Length 0 Invert Slope % Pipe Diameter in) pipe Capacity (cfa) Velocity (Ns Flow lime Inuemenl min 1 A3 2 A2 3 0.15 9 0.90 5 0.14 6 0.14 7 5.00 8 681 9 0.92 10 386.06 11 384.60 12 97.00 13 1.50% 14 15 15 1.4 16 3.9 17 0.42 A2 Al 0.00 0.90 0.00 0.14 5.00 681 0.92 3MAO 38265 116.50 1.50% 15 1.4 3.9 650 At AO 0.]3 0.90 0.66 0.79 5.00 681 5.39 382.45 382.10 23.50 1.50% 15 6.3 6.2 0.06 B1 AO 00] 0.90 0.07 0.07 5.00 681 0.45 385.88 382.10 140.00 2.70% 15 0.9 3.9 660 AO Ex. Str. 000 0.90 0.00 0.86 5.00 681 5.85 381.90 37870 160.00 2.00% 15 7.6 7.1 638 Stormwater Quality Calculations: VRRM Re -Development Spreadsheet om MymragamHdedox/on Me dNmrtlevelopmeM(ampganmSpreodsM1eer- C2011gMPMaMaMaatl SppdNONme C')WUDo BWSs rEraa SWdfi=l m P Jo Name: Sth SVeM landing 5 (Storage Date: 1/3U/2033 BMYOesign Spe[ifiruriam Lisf: Ono dnta x,mrmiprcne:l as .wan...mrnn'ne:l a.m TM I m: REMC(, EMC nxs �mm+IEMCImW I is rgetm Wea 114/eve/yr� OA] rllerm�mnam.eem.l o.m 3.0 Site Results (Water Quality Compliance) Area Checks FOREST/OPEN SPACE (a[) D.A.A am D.A.B 0.00 D.A.0 0.00 DA.D 0.DO O.F.E O.W A.-CHEM OK. IMPERVIOUS COVER(a[) am 0.00 0.00 0.00 0.00 OK. IMPERV��GED TUEAAREA Ia[) 0.00 0.00 DOD 0.00 0.00 OK. MANAGED TURF AREA TREATED Ia[) 0.00 0.00 DOD 0.00 O.00 OK. AREA CHECK OK OK. OK. OK OK. Site Treatment Volume (ks) M5 Runoff Reduction Volume and TP By Drainage Area D.A. A D.A. B___j D.A. C D.A. D O.A. E TOTAL RUNOFF VOLUME ACHIEVED 0 0 0 0 0 LOADAUOION (lb/ TP LOADAVAINBLE FOR REMOVAL Qb/yrI 0.00 O.W 0.00 � 0.00 O.M 0.00 TPIDADREDUCnONACHIEVED)Ib/yrl 0.00 O.00 DOD 0.00 O.W 0.00 TP LOAD REMAINING IIb/yr) 0.00 O.W 0.00 0.00 O.W am MMOGEN LOAD REDUCTION ACHIEVED pb/yrl am 0.00 0.00 0.00 O.W 0.00 Total Phosphorus FINAL POST -DEVELOPMENT TP LOAD (lb/yr)) 0.22 TP LOAD REDUCTION REQUIRED pb/yrl 0.18 TP WAD REDUCTION AOIIFVED lb/yr) 0.00 W WAD REMAINING Qb/N): 0.22 REMAINING TP LOAD REDUCTION REQUIRED (IbIW):l 0.18 Total Nitrogen (For Information Purposes) POST -DEVELOPMENT LOAD IIb/yr) 1 1.55 NITROGEN LOAD REDUCTION ACHIEVED Pb/yrl am REMAINING POST -DEVELOPMENT NITRWEN LOAD Pb/yrl 1.55 WgMa Runoff RMumon ANIp! warolmin DEQ Virginia Runoff Reduction Metlgd New Development Compliane SpreadsM1eM - VeMlon 3.0 oMP Cei�pn Spxifirooans tis[: . She Summary Pon. Tine: Stir .. Landing self smm, ore: usso Talr Rainfall= 6 inches Site land Cover Summary Rmlls BSons CSrls Dire Totals "of'renal Farer/Open(acres) B.UB B.W 0no o.W 7no B Managed Turl(aarm) B.m B.m 0.N o.W 0.. B mpeMow Cuser(acrtx) oao o.loI o.11o o.00 0.10 lao 0.10 ao She Tv and land Cover Nutrient lords xe R 0.. TrealmeM Volume if,,30s Tl Lead(lb/yr) 0.22 IN Load (Ib/n) lss T 1 TP Load Redunion mooned(lb/yrl 0.18 Site Compliance Summary Total Runoff Volume Freudian(W) o Toorl TP Wad ReduNon PCMe¢ed pb/yr) 000 Toorl TR Wad Reduction ANleved(lb/,) 000 Remaining Pml Development TP Wad pbM ri 2 Remaining TP Wad Reduction (b/yr) 0.18 Requlree OAR DAB OA.0 DAD D.A.E Trr fareM/Open(acres) D.W o.N o.no D.DD D.W D.DD Managedld(morm) o.W 11 0.N 1o.00 oo0 0.00 0.00 Impervious Cover(acrm) 0.. 0.N o.00 oao n. oao TWI Arm(aarm) 0.00 O.w o.DO n00 o.0e Win Drainage Area Compliance Summam OA.A DAB OA.0 DA.D DAE Total TP Lead Reduced! Ib/ r o.N o.N o.00 I000 o.00 o.N TN Wad Beduced(Ityr) o.m o.m OR 1 0.m l,e rdorm 2,e rnarm I]o year storm Target Rainfall Evenl(in) 1 3.00 1 3eD 1s.W Drainage Ands RVBCN Dml ye AmmA DnlnageAmB malmge RreaC Dnl ye Area Drainage now RRh o a o 0 0 1-year Mum period!period! RV mna mr n) nCo 000 0.0] oM nCo mfe M r—Id nCo 000 0.00 oao one xaalunea o 0 0 0 0 2,mar Mum period!period! mIr t—n) naD ooD o.DD oar, a. RVW Mr—lnl nCa off r,.W off One Heented o u o r, r, lo-year Mum period Ir t—n) mMr—lnl nCa off r,.W oM nCa nCa off r,.W off nCa Haalvuea o u o r, r, Sumlery Nat Independent Reports: Approved DA Map & Stormwater Calculation Packet — 1AWIXINT1I1I1I:#d Approved Phase 1 DA Map & Stormwater Calculations — SDP201900045 WP0201600082 Drainage Area Maps & Stormwater Management Narrative 1. All dams and constructed fill to be within 95% of maximum dry density and 2% of optimum moisture content. All fill material to be approved by a geotechnical engineer. A geotechnical engineer is to be present during construction of dams. 2. Pipe and riser joints are to be watertight within Stormwater management facilities. 3. For temporary sediment traps or basins which are to be converted to permanent stormwater management facilities; conversion is not to take place until the site is stabilized, and permission has been obtained from the County erosion control inspector. Final Buildout Proposed Impervious Area Summary (For Final Buildout Water Quality Calculations) Phase A Building A 9,500 sf Concrete Sidewalk & Dumpster 4,525 sf Pervious Pavers 4,700 sf Parking Lot Asphalt & Curb 38,17S sf 56,900 sf Phase B Building B 9,500 sf Concrete Sidewalk 2,125 sf Parking Lot Asphalt & Curb 21,075 sfi 32,700 sf Phase C Building C 8,500 sf Concrete Sidewalk 1,250 sf Parking Lot Asphalt &Curb 7,975 sf 17.725 sf OVERVIEW: THE PROPOSED PLAN PROVIDES STORMWATERTREATMENT FOR THE FUTURE DEVELOPMENT OF THIS PARCEL THE PROPOSED PLAN COMPLIES WITH PART 1113 REQUIREMENTS. STORMWATERQUANTITY: CHANNELPROTECTION IS MET THROUGH9VAC25-870-66, SUBSECTIONS B. La AND BA.a. FLOOD PROTECTION IS MET THROUGH 9 VAC25-870-66, SUBSECTIONS C.2.a AND C.3.a. THE PROPOSED DEVELOPMEVTOUTFALLS INTO AN EXISTING CHANNEL THE PROPOSED PLAN ARMORS THE EXISTING CHANNEL CALCULATIONS HAVE BEEN PROVIDED THAT SHOW THE CHANNEL IS NONFROSIVE DURING THE 2-YEAR DESIGN STORM AND ITS BANKS ARE NOT OVERTOPPED DURING THE 10-YEAR DESIGN STORM. THE ADEQUATE CHANNEL ANALYZED OUTFALIS DIRECTLY INTO MOORES CREEK, WHERE THE SITE's AREA IS LESS THAN 1% OF THE STREAM's CONTRIBUTING WATERSHED. SEE THIS PLAN, AND THE ACCOMPANYING STORMWATER MANAGEMENT CALCULATIONS PACKET, FOR DETAILS. STORMWATERQUALII'Y: THESTORMWATERQUALITYTREATMENTFORTHEFUTURE DEVELOPMENT IS PROVIDED VIA THE IMPLEMENTATION OF TWO BEST MANAGEMENTPRACTICES. THE BEST MANAGEMENT PRACTICE OF PROTECTING FOREST & OPEN SPACES FROM DISTURBANCES IS UTII 1Z.ED. A PROPOSED SWM FOREST AND OPEN SPACE EASEMENT WIILBERECORDED WITH THIS DEVELOPMENTS PLAT. AFTERTHE USE OF THIS BNIP A FINAL PHOSPHOROUS REMO VAL OF 2.491bs/yr. IS REQUIRED. PHOSPHOROUS REMOVAL CREDIT'S HAVE BEEN PURCHASED FOR THIS REMAINING BALANCE, ACHIEVING COMPLIANCE WITH PART ILB WATER QUALITY REQUIREMENTS. PLEASE SEE THE ATTACHED STORMWATER MANAGEMENT CALCULATIONS PACKET FOR ADDITIONAL DETAILS. MITIGATION CALCULATIONS: SUMMARYOF AREAS: PROPOSED IMPACTED STREAM BUFFERAREAS: TOTAL 16,685 sf WATERSIDE: 3,035 sf LANDWARD SIDE: 13,650 sf REQUIRED MITIGATION: TOTAL 33,370 sf (AREA>0.25 ac.) WATERSIDE: 6,070 sf LANDWARD SIDE: 27,300 sf SUMMARYOF REQ UIRFIMENTS A PLANTING REQUIREMENT FOREVERY400 sf (OR20'x20' SBCTION) ON THE WATERSIDE BUFFER SHALLOONTAIN THE FOLLOWING: ONE (1) t}" - 2" CALIPERCANOPYTRF.E ORIARGEEVERGREEN AT AHEIGHT OF 6' TWO (2)1% 14" CALIPER UNDERSTORYTREPS OREVERGREEINS AT A HEIGHT OF4' OR ONE (1) UNDERSTORYTREE AND TWO(2)LARGE SHRUBS ATAHEKiI-TTOFT-4' THREE (3) SMAILSHRUBS OR WOODYGROUNDCOVER AT A HEIGHT OF 15"-18" AND B. PLANTING REQUIREMENT ON THE LANDWARD BUFFER SHALLCONTAIN THE FOLLOWING: BARE ROOT SEEDLINGS OR WHIPS AT L210 STEMS PER ACRE, APPROXIMATELY 6'x6' O.C. OR CONTAINER GROWN SEEDLING TUBES AT700. PER ACRE, APPROXIMATELY 8'x8' O.C. THE REQUIREMENTS ABOVE EQUATETO THE FOLLOWING MINIMUM MITIGATION PLANTINGS: A (WATERSIDE50') AT A HEIGHT OF 6' (IS)1}"-2"CAI.IPER CANOPY TREES OR LARGE EVERGREENS HT OF 4'OR YTREES OR EVERGREENS ATAHEIG 30 "_ 1 "CALIPER UNDERSTOR ( ) } IS UNDERSTOR YTRF.FQ AND 16 LARGE SHRUBS AT A IiE[GITTOF3'-4' (46) SMALL SHRUBS OR WOODY GROUNDCOVER AT AHEIGHT OF 15"-18" B. (LANDWARD50) 759 BARE ROOT SEEDLINGS OR WHIPS, APPROXIMATELY6 W O.C. OR 439 CONTAINERGROWN SEEDLING TUBES, APPROXLMATELY8'x8' O.0 GF'NFRALNOTES: L THERE IS AWPO STREAM BUFFER ON THIS SITE, AS SHOWN ON THE PLANS. THE 100' WPO BUFFER SHAI L BE 100' OFF THE EXISTING STREAM's BANKS OR 100' OFF THE LIMITS OF THE WETLANDS, WHICHEVER IS GREATER. 2. ALL PROPOSED DISTURBED AREAS WITHIN THE 100'WPO STREAM BUFFER SHALL PROVIDE TWICE AS MUCH AREA FOR MIT(iATTON. 3. -MITIGATED AREAS SHALL BE PROTECTED BYMAINTENANCE AGREEMENTS, TO BE EXECUTED BYTHE OWNER PRIOR TO PLANTINGS. 4. ALL MITIGATION PLANTINGS SHALL COMPLY WITH THE RIPARIAN BUFFERS GUIDANCE MANUAL BYCBLAD. 5. IXR's RIPARIAN BUFFERS MODIFLCAT10N &MITIGATION GUIDANCE MANUAL DEFINES ACANOPY TREE AS A TREE THAT REACHES 35' IN HEIGHT OR LARGER WHEN MATURE. THE MANUAL DEFINES AN UNDERSTORYTREE AS ATRRE THAT MATURES TO A MIGHT OF ITTO 35'. ALARGESHRUB IS DEFINED AS A SHRUB THAT REACHES 10' OF HEIGHT OR GREATER AT MATURITY, AND A SMALL SHRUB IS DEFINED AS A WOODY PLANT THAT CAN REACH UP TO 10' OF HFIGHr AT MATURITY. o' srR BUF / / // / , PRE -DEVELOPMENT: SCALE =50' OM 0 ES EEC/ J / _ 100 YEAR FLOODPLAIN, /j yy wps°.-� r-� -•�'7 - L PLACEMENT- / ` pl / / / ♦♦ 1 ® ° A�010. �' �.. MOORES CREEK .M1�dQN, Qj 9Q \ /1 / j / ♦ // ° ® a ° I ��® �. ; AS. AND APPRROVEO BY-. e "...Ati ..... E'.COU Ta'F OS: . /JC a.uac. o J /'\ / a�r�u�--yes - � � /�•�®® / / CN=66.5 //t%�,� /-d' Tc=o.11hrs. `'/ EXIST Ri,'�f / / t I I \ - / / Tc=0.11 hrs.j- T TE6G100' OF OLF w/ 4 ELEV.=14' ����• ....: \\80' OF CONC. FLOW' w/ A ELEV.=1_,! ��° t',..... r....... EXISTING SEDIMENT1( �� r...... TRAP APPROVED / //..' i /'sr V \\ /1 \ } } / I / ✓ / \\ UNDER WPO I {!. . At J1, i�_01 ..,, SWN ORM SEWERS m"•x'wl D 0&REDIRECTS �� ! ///� 6 \\'1 ////� 1� / •� /'� /L ......._........... wnr RUN LL(,.CO TINUETO nre ,............ .'....'.'.'.'.'.'.'.'.'.'.'. ` I UT N E ANTE\ :.. ..� .....'.:..'.:..'.:..'..'.. Cb I ' J7 AR \\ % / / r......... r..................... ..... 1 t ' .............................. DAB �I ° / , ......:...::.....'. HOLIDAY INN 1 ac. /^\ �.® o / ,....... /....................... wwar w (Is- CN=56.z Te-o.23 hrs. / <.....:.:.:.: .....'..... j..'.'.'.': .': ! / S ,....... �.../.................. / / 1 ........ 1 ....:/.'.'.'.:. .... \ �► / 1 / !oft AW�.:.'t..... # r...... _FOODWAYf.::::.::.:... y....... /..'.'.' x.':..'.'.'...........f: ®f tar♦d t [:':':':' ::':f::::':':'::':':':':':':':. ....J j.'.'. ...............'.' hrs. •, o�.9��$'�j e .. 'an ....i......................... 100' OF OLF w/ A ELEV.=21' ) _ ..... ✓/..'.'.'.. 185' OF CONC. FLOW w/ A ELEV.=1' w / .......... ...................:'.'.// .-...... o ® ® ® ® ® ® e .. :. ..'.'..'f/ // f Pre -Development DA A Impervious Area Summary _x ���/ r"""'""I ° ° o ° © o 0 0 0 � - \ , /'� J� JJ / (For Pre -Development Water lQuantityCalculations) / """' ems. // :. . Entrance &Holiday Inn Parking Lot 12,375 sf s g - .. 100' STREAM BUFFER FROM BISCUIT RU & ' 5thStreet Pavement _ 3?25 sf, PROPOSED GREEN WAY EASEMENT AREA 'NO Total = 15,500 sf y' \ pI$TURBANOE AREA, BASED ON SP 2007- 0063' // I / / OLIO INSTALLA RIPRAII NEB OUTFALL. - \\\ CHANNEL At�rQUAC Y PLANs : ate r^=aoo' / / FE'QUTLET PRO ON RIPRAP APRON/ CHANNEL f � r APy't' - -' �\� _ LOCATION OF ADEQUATE CHANNEL OUJFALL INTO } 1} \ \ �� -";✓` " DESIGN'NOTEVON SHEET 6, AND THE PROFILE. /,ram' r MOORES-CREEK. LOCATION REPRESENTS THE POINT ADDITIO AL CALCVL1 ATIONS. HAVE BEEN PROVIDED. / ,� �'.' l y. - WHERE THE STTE's CONTRIBMNG.SUBAREA IS \}}}} } /ir jj / /j / ///��- �� y// I a! - l .: ��•,. LLESS THAN 1% OF MOORES CREEK'S WATERSHED. .. 4� /ram- _ 4.) 5?A.- CREEK \ O� «-4 .O18has.: I � OX[MATELOCATION OF DR l(I AINAGE DMDE DEPICTININ G r /,%.� / // //////� , , \ Z \ / `�• ADDITIONAL SHEET FLOW ter✓ / L /' /// /jj/// j� O % //�lj i t i \, \ r /� 1 / . RUNOFF WITHIN THE 100 YEAR iN f /� /.✓/ f//////� J t t i!b�� /` -\ Cl r / _ FOMS DRAINING TO THE PR / J� / (/ // ///% //' ♦ I � % / J'(y' � � � c _ h .� THE PROPOSED OUTFALL_ ( 1 ) i \ I \ t_ WATERSHED SUMMARY Pre -Development 127.i30=iriii-aiti x 2-year Flow, 10-year 2-year Flow, 10-year CN Area, ac. CN Area, ac. cfs Flow, cfs cfs Row, cfs DATA' 66.5 2.11 2.84 6.79 88.3 3.25 12.54 21.56 DA-B' 56.2 1.14 0.55 2.12 DA'C' - - - - 57.7 0.09 0.05 0.19 DA'D' 1 79.2 4.11 9.15 18.10 Total= 21.75 39.84 / 1. SERTROPOSED OUTLErPROTECTION DETAIL TW..: { 1 ''/" ONTHLS SHEET. ?': , 2. SEE'PROPOSEDRIPRAPCHANNEu DETAILON -. '- THIS SHEET. t :..3. SEETHE'RORAP OUTLET SECTION AT MOORES ' -: CREFKDETAI.ONSHEET3. 0 4. SEETHE'OUTLET PROTECTION RIPRAP APRON/' CHANNELDESIGN' NOTES ON SHEET 6. rttvruonu vu iws Tau icw. ]wc� (AT OUTLET' OF STORM SEWER) 9.3' AWE X KIDE o� rr PIPE OOTLECPROTECTgN (OP)NOTES: 1. OP SHALL HAVE A 0 % SLOPE. 2. RIPRAP APRON SHALLEXIPNDTO TB RIPRAP DITCH. 3. RI'RAP SHALLBE VD OTCL Al STONE. 4. OP SDESLOPES TO BE 5. 3:1 WITH ADEPTH OF 2' PROPOSED SWM FOREST & OPEN SPACE / EASEMENT IS LOCATED OUTSIDE THE - LIMITS OF THE PROPOSED ADEQUATE CHANNEL. SUCH A DESIGN ALLOWS FOR THE SITE& ADEQUATE CHANNEL TO OUTFALLATAPOINTWHERETHESITE's CONTRIBUTING DRAINAGE AREA IS LESS THAN i%OF MOORES CREEK'S ,l WATERSHED. PROPOSED STREAM BUFFER IMPACTS TOTAL= 16,685 sf I - / ( _ WATERSIDE: 3,o35 sf _ y LANDWARD: 2165osf ` I` SWM FOREST & OPEN SPACE EASEMENT NOTES: 1. NUTRIENT CREDITS WILL BE REQUIRED TO BE PURCHASED FOR THIS DEVELOPMENT PRIORTO VSMP PLAN APPROVAL.'SWM' IS AN ACRONYM FOR STORMWATER MANAGEMENT. z. THE SWM FOREST AND OPEN SPACE EASEMENT IS SUBJECTTO THEGUIDANCE SET FORTH BY DEQ IN THE VIRGINIA STORMWATER MANAGEMENT PROGRAM . THE AREAS WILL REMAIN UNDISTURBED IN A NATURAL, VEGETATED STATE EXCEPT FOR ACTIVITIES AS APPROVED BY THE LOCAL PROGRAM AUTHORITY, SUCH AS FOREST MANAGEMENT, CONTROL OF INVASIVE SPECIES, REPLANTING AND REVEGETATING, PASSIVE RECREATION (e.g. TRAILS), AND LIMITED BUSH HOGGING TO MAINTAIN DESIRED VEGETATIVE COMMUNITY (BUT NO MORE THAN FOUR / TIMES A YEAR). MITIGATION NOTES: a. CONTRACTOR SHALL ENSURE INVASIVE SPECIES ARE REMOVED PRIOR TO ANY MITIGATION J PLANTINGS. CONTRACTOR SHALL NOT HOWEVER REMOVE ESTABLISHED VEGETATION ALONG STREAM BANKS, EVEN IF INVASIVE. PER US CORPS. OF ENGINEERS, THESE PLANTINGS ASSIST WITH THE STABILIZATIONOF THE STREAM. 2. THE MITIGATION PLAN SHOWN PROPOSES PLANTINGS WITHIN THE STREAM BUFFER AND IMMEDIATELY ADJACENT TO THE STREAM BUFFER. BECAUSE THE PROTECTED TECTED EXISTING STREAM BUFFER TO REMAIN UNDISTURBED IS HEAVILY VEGETATED, THERE IS LITTLE ROOM TO PROPOSE NEW PLANTINGS. 1 3. IN LIGHT OF MITIGATION NOTE #2 ABOVE, AND THE FACTTHE PROPOSED PLANTINGS ARE LESSTHAN THOSE REQUIRED IN THE CALCULATIONS SHOWN ON THIS SHEET, AN ARBORIST SHALL BE HIRED BYTHE DEVELOPER TO VISITTHE SITE. THE ARBORIST SHALL MEET WITH COUNTY OFFICIAL(s) AND EXAMINE THE STREAM BUFFER. DURING THEIR MEETING EFFORTS WILL BE MADE TO ENSURE THAT MINIMUM MITIGATION PLANTING REQUIREMENTS ARE MET, OR TO CONFIRM THE EXISTING STREAM BUFFER's LANDSCAPING IS SATISFACTORY. 4. THE ARBORIST SHALL LOCATE AREAS TOTALING 1o85 sf(6,o7o-3,o8S)OF SPECIES IN THE v PROPUSEDRB•RAPCTIANNFI. WATERSIDE 5o OF THE BUFFER THAT ARE INVASIVE, DISEASED OR DYING AND REPLAC- / Total Phosphorous Removal Required for the Full Buildout 4.61 Ibs/yr Phosphorous Removal Achieved from the BMP Practice of the SWM Forest & Open Space Easements 2.12 Ibs/'gr Remaining Phosphorous Removal Required to be Purchased 2.4S Ibs/'rr TH Lie. No. 02 Q J W t ®� /k A \i 922 H `u 7 Z b d N W u 0 Z J 0 V) O L ? W t (/4 LU in W FrIFIMENJ IA■■■E 9 L5 N U Z CL ° -- ILL C m 0 � 3 r A 1�yTy co ° N 1 � CC5) � > o C\I �• o N3 y d N LU z� d y 5 'c- /C� V C\II L 0ALM Li L 0 v LU o ® > LU LU _JJ Y • V o d o 2 3 Z IAI ..P c < J 0 0 I/"�\ �,,,/ LUd m ip LU R > 2 o 0 \/ Cz U) z tl a U�J LU c LU C a c t pS �„j � c a 0 }' i ] LLJ e U lT_ S (D CD Lu N LL ii (n ; JOB NO, 12 3 093 SCALE AS SHOWN SHEET NO. 7 WP0201600082 Stormwater Management Calculations Packet 5" STREET COMMERCIAL DEVELOPMENT STORMWATER MANAGEMENT CALCULATIONS PACKET Date of Calculations DECEMBER 12, 2016 Revised on FEBRUARY 9, 2017 Revised on APRIL 27, 2017 {Final revisions are limited to the adequate channel's Riprap Calculatrons)j PREPARED BY: C 0 L L I N S G1,4Gl iEffF- R, ING 200 GARRETT STREET, SUITE K CHARLOTTESVILLE, VA 22902 434.293.3719 PH 434.293.2813 FX www.collins-engineering.com APPROVED by the Albemarle County Community D v lopment Department Date File iarA 4o/Q 00,0W SCS TR-55 Calculations Soils Mapping (Source: NRCS Web Soil Survey Online Database) Soils Table (Source: NRCS Web Soil Survey Online Database) Map Map Unit Name Percent Unit of A02 Symbol 22C3 Culpeper clay loam, 7 to 15 1.5% percent slopes, severely eroded 39E Hazel loam, 25 to 45 percent 20.8% slopes 47C Louisburg sandy loam, 7 to 8.1% 15 percent slopes 47D Louisburg sandy loam, 15 to 3.4% 25 percent slopes 76 Riverview loam 53.0% 95 Wehadkee sift loam 13.2% Total for Area of Interest 100.0% Note: The soils' properties for this development are predominantly composed of hydrologic types A & B. rPr t00m Soofi POINT PRECIPITATION FREQUENCY (PF) ESTIMATES NTH 90 % CONFIDENCE INTERVALS AND SUPPLEMENTARY INFORMATION NOAA Arias 14. Volume 2, Version 3 PDS-based precipitation frequency estimates with 90 % confidence intervals (in inches)" Amag recurrence ml ni (yews) DUrAtbn ���� ID 25 50 IDO ( 200 500 1000 24 nr 3.64 R74-341) 3.68 (332-413) j 4.71 I f422528) 5.67 (498-622) S." (607-761) � � ) 9.15 (799-10t) 10.5 11 (906-116) 12.5 (106-136) 143 (119-157) U.S. Department of Agriculture Natual Reaoumea Conservadon Servke m 55 Workslreet 2: Runoff Curve Numberard Runoff FL-ENG-21A D6/04 Project: Sth Street Commerolel D.Ibp..m Designed By: FGM, PE Date: 2/9/2017 Leeatbm 5th Street Checked By: SRC, PE Date: 2/9/2017 Clwck One: Present X Developed X 1. Runoff curve Number(CN) DD.ripArea Soil name and Coverdescription Area Protl ON Chl wei = ( Calculaad'S' Deuriptbn hydrologicgwup (fovertype,treatmerK, and hydroioglc condition; pemaM impervious; ON (Acres) Ara. xArea total product/ .duo Value (Appendix A) uwonnetted/wnrotted imperviousane ratio) ronbrea MA Impervlous Aaas 9B 0.36 34.9 (Present) B Woods in Good C mdlltion 55 0.26 24.3 66.5 5.04 .awns In Good Condition 61 L49 911 DAB Impervlous Areas 9B MCD D.D (Pasend) B Woods In Good(rendition 55 0.92 5D.6 S&2 7.81 Law. In Good Condition 61 0M 13A DAA&B Impervlous Areas 98 2A1 235.9 (Developed) B Woods In Good Condition 55 0.05 23 883 132 .awns In Good Condition 61 0.79 48.4 Impervlous Areas 98 116 211.7 DAD B Woods in Good Condidon (For Channel Adequary Cal=Onty) 55 0.87 479 79.2 2.63 Wwns In Good AdRbn(For Channel Adequacy talcs Orel 61 1.001 0.9 ImpervlOusArear 96 0.00 0.0 DAC B Woods in Good Condition(For Channel Adequary Wke Only] 55 0.05 18 57.7 7.34 awns In Good nditlon(For Channel ASlaquary Calu Only) 61 DA4 2A 2. RunoN 1-Year Storm 2-Year Storm MYYearStotm Drainage Area Description Frxxwaars 1 2 1D Na Raln%14 P(24 haurl- Inches 3A4 3.0 537 n/a RuroN Q-Inches 0.58 0.95 2.17 DAA Pasant RunoN,Q-Inches 0.24 DAB 1.36 DA IS(present) RuroN Q-Irohas 1.88 2A7 4.3 DAA&B(Deveb d) Ruroff, Q-Inches Rurofi Q-Inches 1.23 1.73 3.32 DAD Ruroff, Q-Inchas 0.211 0.52 1.47 WE U.S. Department of Agriculture Natural Resources Conservation Service TR 55 Worksheet 3: Time of Concentration (T,) or Travel Time (T,) Project: Sth Street Commercial Development Location: Sth Street Check One: Present X Developed X Check One: T, X T, Segment Sheet Flow: (Applicable to T. only) Designed By: FGM, PE Checked By: SRC, PE Through subarea n/a FL-ENG-21A O6/D4 Date: 2/9/2017 Date: 2/9/2017 DAA DAB DAA&B D: (Present) I (Present) (Developed) DAD DA C 1 Surface description (Table 3-1) Dense Gress Dense Grass Dense Grass 2 Manning's roughness coeff., n (Table 3-1 0.24 0.24 0.24 3 Flow length, L (total L < 100) (ft) 1.00 100 100 4 Two-year 24-hour rainfall, P2(in.) 3.7 3.7 3.7 5 Land slope, s (ft/ft) 0.14 0.21 0.05 6 Compute T, = [0.007(n-L)OI / P,° S" 0.10 0.09 0.15 Shallow Concentrated Flow 7 Surface description(paved or unpaved) Unpaved Unpaved Unpaved 8 Flow Length, L (ft) 80 185 490 9 Watercourse slope, s (ft/ft) 0.013 0.005 0.061 10 Average velocity, V (Figure 3-11 (ft/s) 1.8 1.2 4.0 11 T,= L/ 3600'V 0.01 0.04 0.03 Channel Flow: 12 Crass sectional flow area, a (ft') 13 Wetted perimeter, P. (ft) 14 Hydraulic radius, r = a/Pw (ft) 15 Channel Slope, s (ft/ft) 16 Manning's Roughness Coeff, n 17V=[1.49r..S's)/n 18 Flow length, L (ft) 19 Tr= L / 3600-V 20 Watershed or subarea Tor Tt (Add T, in steps 6,11 and 19) 0.11 0.13 0.10 0.18 0.30 U.S. Department of Agdalture Natural Resources Conservation Service Project: 5th Street Commercial Development Location: Sth Street Check One: Present x Developed % TR 55 Worksheet 4: Graphical Peak Discharge Method Designed By: FGM, PE Checked Br. SRC, PE FL-ENG-23C 06/04 Date: 2/9/2017 Date: 2/9/2017 1. Data Drainage Area Description Drainage Area Description Drainage Area Description Drainage Area Description Drainage Area Description Drainage Area Description DAA (Present) DAB (Present) DAA&B (Developed) DAD DAC Drainage Area (Am) in miles2= D.D033 0.0018 0.0052 O.OD64 O.ODOS Runoff curve number CN= 66.5 56.2 B8.3 79.2 57.7 Time ufconcentration(Tc)= 0.11 0.13 0.10 0.18 0.10 Rainfall distribution type= II II II II II Pond and swamp areas spread throughout: the watershed= 0 0 0 0 0 2 Frequency -years 1 2 10 1 2 30 1 2 10 1 2 10 1 2 10 3. Rainfall, P (24 hour) -inches IN 3.69 5.57 3.D4 3.69 5.57 IN 3.69 5.57 3.04 3.69 5.57 IN 3.69 5.57 4. Inldal Abstraction, la -inches 1.02 1.01 LO1 1.56 2.56 2.56 0.26 0.26 0.26 0.53 0.53 0.53 1.47 1.47 3-47 S. Compute la/P 0.33 0.27 0.18 0.51 0.42 0.28 O.D9 0.07 0.05 0.17 0.14 0.09 0.48 0.40 0.26 6. Unit peak discharge, Qu- am/in 875 925 950 475 675 875 1000 1000 100D BOD. 825 850 500 750 900 7. Runoff Q from Worksheet 2-inches 0.53 0.93 2.17 0.24 0.45 1.36 1.88 2.47 US 1.23 1.73 3.32 0.29 0.52 1.47 B. Pond and Smmp adjustment factor, Fp 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 9. Peak Discharge, Qp- cfs where Qp=Qu Am QFp 1.59 2.84 6.79 0.20 0.55 2.12 9.54 12.54 21.56 6.31 9.15 18.10 0.02 0.05 0.19 WATERSHED SUMMARY Pre -Development Post-Develoomerd 2-year Flow, 10year Flow, 2-year Flow, 10-year CN Areau a' cfs crs CN Area ac. cfs Flow, cfs DA'A' 66.5 2.11 2.94 6.79 DA'B' 56.2 L14 0.55 2.12 88.3 3.25 12.54 2L56 DA'C' - - - - 57.7 0.09 0.05 0.19 DAD' 792 4.11 9.25 18.10 Total= ZL75 39,84 Adequate Channel Analysis to Moores Creek (The following 6 sheets are the only revisions made to the previously reviewed &accepted` _ _. SWM calculations packet.). 5th Street Adequate Channel Outfall- 2-year Complex Channnel- Trapezoidal Riprap Lined Adequate Channel (2-yr) Input: Slope Flow (given) Output: 0.010 21.500 line x y n 0 0.000 2.000 0.050 (first n value not used) 1 6.000 0.000 0.050 2 7.000 0.000 0.050 3 13.000 2.000 0.050 Depth 1.491 (y) ( 1.491) Channel bed segment output: line Q V 1 7.86 2.36 2 5.78 3.88 3 7.86 2.36 Wed Apr 26 10:20:18 EDT 2017 A P 3.33 4.71 1.49 1.00 3.33 4.71 Page 1 5th Street Adequate Channel Outfall- 10-year Complex Channnel- Trapezoidal Riprap Lined Adequate Channel (10-yr) Input: Slope Flow (given) line x y n 0 0.000 2.000 0.050 (first n value not used) 1 6.000 0.000 0.050 2 7.000 0.000 0.050 3 13.000 2.000 0.050 Output: Depth 1.923 (Y) ( 1.923) Channel bed segment output: line Q V A P 1 15.50 2.80 5.55 6.08 2 8.84 4.60 1.92 1.00 3 15.50 2.80 5.55 6.08 Wed Apr 26 10:19:55 EDT 2017 Page 1 S ke • CAPS. �r . 1��'PA'� ST�e S3��t•�6. /CER VES.ct-t :PQPC-.*�iT .S,i9 a� FGM �E htPiiaP St+AtL 6E 5 P ev ga[n 53r&s VF- 'TN,- rKIIWXL a Rx.opAD SHALL 6r %iF ciE O, K-' owXY l CHANNCLY i � lOflT( a'� 06�tM o� Hjo at., YtzeV3,e CKAIJPcc �`r1Y\AYMWI QE(r,H of FiaO ar,� t?zvii11 C.NRNNU-� �.� (150D ec0 GCSa'Gv CAL(t.Ll; �cV•� t3' • blv �^-nbrri k LA � �'�EF THE A1'rAtNEO Rur+s 3.tq- C raR P �' o�:4:Ft � cNAw.oCt ` p S� OEESNE;7 SY JO^/. >F •]Hti a"raaE'6S W6a 6t1'T WILL 13L' SMAu6A l',1Far. l"HL SOELI =3E`, j" OTAMF'eC'R. i,Av C:S,cR[,. 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CANC.?, t,foNa \nlaUKvQr- W-Ujw, &a-* BAVX5 � -3TOVS 1 of 1 VDOT Drainage Manual Storm Sewer Computations (The proposed plan simply redirects the existing storm sewer, however calculations have been provided for informational purposes showing it can handle the future development.) $ 'o F m �—' SIeNnB $INGiYre m m N Z O O O Ending Struaure y 4O C_ p e u g o � m D2inge area (acres) . renonel art. x merem.a ea � sum socumulaee � 8 c, Eme atone (min) I, reiaell InI.IG¢ a�mse Om lncr.(as) �s Irnatln (fl) ` II O w Im«oul(m lengN (M L n, manning% ccaR. II O O e o a mega a x mg m D. gemebft A A A A V. velowy (fps) Flow Time(min) RemeMs Design Year: 10 Hydraulic Grade Line Calculation Project: 5th St. Job M 132093 Prenared bv: FGM. PE INLET STATION OUTLET WATER SURFACE ELEV i, P. Q. ZW S., Hr FUNCTION LOSS ............. .... ...... .... ......�........... ...�....� .. .....................�..................._ __.�� ......................... V, H, Qp Vn Q•V, V,'/lg 34 ANGL6 ne H. 1.31y .5N, FMAL H M WATER SURFACE E: RIM ELEV 376.00 58.31 30 15.13 0.001 0.09 7.4 0.2 2 7.4 4.9 36.2 0.4 0.13 0 0 0.34 N/A N/A 0.42 376.42 390.33 379.02 97.66 30 7.37 0.000 0.03 4.9 0.1 4 6.9 4.8 33.4 0.4 0.13 180 0.25342 0.47 N/A 0.24 0.27 379.29 391.50 379.61 112.051 30 6.93 0.000 0.03 4.8 0.1 6 6.9 4.8 33.2 0.4 0.13 150 0.25342 0.47 N/A 0.24 0.27 379.88 391.50 380.27 64.43 30 6.87 0.000 0.02 4.8 0.1 8 6.9 4.9 33.4 0.4 0.13 180 0.25668 0.48 N/A 0.24 0.26 380.53 389.95 380.53 90.96 24 6.87 0.001 0.08 4.9 0.1 10 5.0 11.9 59.6 2.2 0.78 95 1=0.72 3.14 1.57 1.66 382.18 390.52 382.18 76.88 15 4.99 0.006 0.46 11.9 0.6 CULVERTI_ I 0.00 180 0.36 0.82 383.00 385.66 Hydraulic Grade Line Page 1 DEQ Virginia Runoff Reduction Method Water Quality Calculations (COMPLIANCE IS MET THROUGH THE BEST MANAGEMENT PRACTICE OF PROTECTING FOREST & OPEN SPACES AND THROUGH THE PURCHASING OF NUTRIENT CREDITS) _ - Drdi Vlrp(nfpRYmtrfjFeobmton MRthodNew ORvelopmeat Cvmptldnce Spraudsheyt •Vef5i0n 9A - ..'.' .. .. ... . (E2011 BNW SmatH.Mamt6peeMwtgiu 01D19 Dnk 0MV Smndards nd5peciRcedoni f Pm}m Name: ` SWStreet Commercial DewI ent• Full Bulldout I �( dalalnputmlb Dam: I31/2016 .dnstentvalues 8MP OeStp SMdpmfkm Mt. 1011 Stds & Spem mfwlatlpn mils Site Information i Post -Development Project (Treatment Volume and Loads) Land toner (acres] ASolls BSoDs CSolb I oSolb L romis FPrest)apen Spax (mrenl—undatubed, _ S.S. roreeed tares o Ed tend 0.55 5AB Managed Tudleces76 dlsrubed graded for �- 23Z Nsermhereudmbemo m m M 2B1 4nPervbusruaer(aonl 1.46 2A6 'FmNDpen SPare anmsmust lepmferre!(n ncmrdnnm wMr MieV4pMieRu nFelutllan MCMed M41 Constants Runoff CokMs Ry MnuOR Pnnlllmcney 43 ASolls 1 BSolb 1 [Sall. 1 Snll. ]Tager R.IWA Event lPuhes i LW Fwest/Opm Spe¢1 0.01 - DA3 O.ed 0.05 (total Phosphorus(TP)EMC(mg/L) 0.W Mena Turf 10.15 0.D0 0.01om Total Ni rogen D EMC (mg/L1 1.86 M m Corer1 D.95 095 I e95 1 0.95 Tmget TPlaad Ib/-1,) D41 P Unki. mnemion fattaq 0.90 FP.VOpen Spare fiver (acreal 5.64 Treat.ttVVp(lume O.MTO Tm ftneMVobme(cubirfeet) "Im TP mad(Ib/yrl 695 TN lea Yr,4qJ7 Weighted Rv(fpmst) DM %Fdrett 54% Mnnyetl Turtmver lames) 231`. Weighted Ra(tur0 030 %Managed Tort E% Impervbu. Corm(araes) 2A6 W(ImpeM.) 0.95 %ImpeMons M% 1 Ate Rv I om L — \ MANHOLE-Wp0201600082 Revised Outfall Analysis _ Top=3�9 APPROVED a \ )N T IN=371.74 •..'`j` j \\ j �INVE UT (8'" DlP)=371.69 by the Albemarle County Community Devel pment Departmen, Date fe 7 9' ^0 1P \ File wPU 2ol u ooat7l, _ Z\ 1360 \\ SEE APPROVED VSMP PLAN #1, SHEET 2's 'RIPRAP n \\\ OUTLET SECTION AT MOORES CREEK' DETAIL FOR \ \\\ -,DESIGN OF RIPRAP BETWEEN THE STREAM'S BED $ W - EDGE OF \ '-,TO A POINT 3' ABOVE THE STREAM's EDGE. E — %STREAM=365.0t NEL�' DIFlED PU S-WEST A Di 9PEN - \ \ __. -- --- -� �� - - ----- -- E PACE/ MENT (0.116 ac. — DB . 4, PG.. 732. (PLAT)- \ VA -- 4909, PG 508-517 3•j y `� (MAINTENANCE EASEMENT) MODIFIED DITCH's RIPRAP TO 8E UPGRADED TO CL. III RIPRAP. ! BEGINNING OF MODIFIED / CHANNEL (INV. 374.00)= OUTLET OF APPROVED PIPE- (INV. 374.00) IRPA \ \ OL_ 18. •� �� (PER VSMP #1 PLAN, SHEET 7) 1. RIPRAP SHALL BE STABLE ON BOTH i ' SIDES OF THE CHANNEL & BOTTOM. APIP�ROyLPO TR RIPRAP SHALL BE GRADED. \ RIPRAP i - 'NO SCALE a a //`TYP.)�` I U S 3 \ Q2 = 21.50 CFS e %RIPRAP-LINED OUTFALL NOTES: V2=6.73 FPS -1. CONTRACTOR SHALL NOT INSTALL THE 17' LONG LEVEL OUTLET PROTECTION AT THE PIPE's OUTFALL. CONTRACTOR SHALL INSTEAD BEGIN Q,o=39.84 CFS S THE MODIFIED RIPRAP LINED CHANNEL AT THE OUTLET OF THE PIPE AND EXTEND IT TO AN ELEVATION 3' ABOVE THE STREAM's EDGE. D,0=1.30 FT 2. MODIFIED RIPRAP LINED CHANNEL (V-SHAPED DITCH, 18• DEEP WITH 3:1 SIDE SLOPES) SHALL HAVE A NEW LENGTH OF 45' AND A NEW SLOPE=13.37.) E SLOPE OF 13.3X 3. RIPRAP LINED CHANNEL TO BE CUT IN WITH 3:1 SLOPES ABOVE THE CHANNEL's TOPS OF BANKS, AS SHOWN. 0 4. RIPRAP LINED CHANNEL TO BE UPGRADED TO CL. III RIPRAP. IN ACCORDANCE WITH THE APPROVED VSMP PLAN #1, RIPRAP SHALL BE PLACED IN A TOE TRENCH WITH AN EXTRA DEPTH AT THE TOE OF THE BANK. SMALLER STONES SHALL FILL THE VOIDS TO FURTHER REDUCE THE RISK OF MOVEMENT. RIPRAP PLACEMENT SHALL EXTEND INTO THE STREAM. PLACEMENT OF STONE WITHIN THE STREAM SHALL BE LIMITED TO THE EDGE OF THE STREAM, AND ONLY EXTEND INTO THE CHANNEL BOTTOM APPROXIMATELY 3'. STH STREET COMMERCIAL DEVELOPMENT SCALE COLLINS = N G I N E E R I N G 1- 20 RIPRAP LINED OUTFALL ANALYSIS 0 200 GARRETT STREET, SUITE K - CHARLOTTESVILLE, VA 22902 - 434.293.371 EXHIBIT 1 SHEET Iof1 -A!w>m....a w.�.,.a eoo.,,w,. w m. w " w Y o, w z o+ G ma mor .an. ,wroe.wa M "do or :..., -d dha .., e..w m any roo....n.,wew.. m. otw e., .., n.. m .w.il W. base.. mey......w.,w, dokn. Vm t u..m..w .m,w w.wm 0 c S uwar N& u N Ac; E q VCsCK SPEC- 3.ty N-C M-„ � Fox fro" wr TLCU: O Mrs. 1oyr 11, 1--M Pr MMMNe r="6TzwJ CwAW,r.l 9lAQE= \Z.339. pef- UTS 3k9--as, TKs ko Stzs CF *- uoot rL. IT- 149W tkhS %..- t,Oro Ws. ctim iEL SSnE "CS ARE ZA. -rKmcr a 'DcsxaN'PDCEaQE s.S CO"kv%xT faa CLOXCn �70WQ ' o, \z 5a 1.0 d'so x k3 = a,o x t.o = a.o' Cam,. altFALL 6N 113 NOCE--*7K5 TPrJQC,-)T FLOW '\ZOOP k)XSt6N CLL. -M '�+� P �p= ca.a 1 MC-CTS -ME RE9U31iE1�EN `S J Fcu TKE CLANEO FLU. A FINAL CL WPM 'tKW16toVc 'ME 0", tfAL. CWNI� MEGIS QESCN 3.19 SQYF=cArza�S Modified Channel with New Slope- 2 Year Complex Channnel- Modified Channel Outfall- 2 Yr. Design Storm Input: Slope 0.133 Flow (given) 21.500 line x y 0 0.000 1.500 1 4.500 0.000 2 9.000 1.500 Output: Depth 1.032 (y) ( 1.032) Channel bed segment output: line Q V 1 10.75 6.73 2 10.75 6.73 Mon Jun 04 15:17:28 EDT 2018 n 0.050 (first n value not used) 0.050 0.050 A P 1.60 3.26 1.60 3.26 Page 1 SDP201900045 Drainage Area Map & Stormwater Management Calculations POST -DEVELOPMENT NOTES: Je,.HUF � k`. l •� a. THE. GRADING S QW REPRESENTSTHc PROPOSED 4" ES ` r CONTOURS ASSOCIATED WITH THIS VSMP PLAN. FROM APPROVED PLAN n� x. THE PROPOSED DRAINAGE DIVIDES, BOTH IN LEVEL OF IMPERVIOUSNESS AND SIZE, REPRESENT THE FULL WPO 201600082 BUILDOUTOFTHISPROJECT. THE STORMWATERQUANTITY r ' AND QUALITY TREATMENT PROPOSED WITH THIS PLAN / y • h REFLECTTHISFULL Btl1iDQUT. 3. A FINAL SITE PLAN 15 REQUIRED FOR THE CONSTRUCTION OF THE PLAN CONCEK UALLY SHOWN BELOW, xrTHE TIME r. � r4 ,- J ✓ � f �= u 3 OFTHEFINAL SITE PLAN'SRkvwwTHEPLAN WILL BE VERIFIED FOR GENERAL COMPLIANCE WITH THIS MAPIPLAN. �" ,y ,,°�"r �i��„WfJ'�,. �;� .',,'. ,�c�n'g''. .:.•�,. �F•_'�;�`" �, � `�• \-/" }�14Si'r 1 � ,fi J�it � ` f 7 y.� c+.S' ;'�''- I a r urN. � f .t A� P � �� \A 4•� r .. _ L :. hf.Y" x c a RJ m ,� it t +. f oS#r r t /i ' f�fl In /. `-,.. �>ikK ` �•�, . / / � Post-Deve(aprnent DA A & B impervious Area Summary (For Final Buiklout Water C2uantityGaicidations) Buildings 27,500 sf f// Concrete Sidewalks & Dumpster pad 6,225 sf _ I Pervious Pavers 4,700 sf }r; Parking Lot Asphalt &Curb 66,410 sf I Total a 104,835 sf CN FOR WPO 201600082 Forest/Open Space -- undisturbed, protected forest/open space orreforested land ManagedTurf -- disturbed, graded for yards or other turf to be mowed/managed Impervious Cover 100' STREAM BUFFER FROM EIISCUIT RI PROPOSED GREENWAY EASEMENT AREA A Solis B Soils (acres) CN (acres) 39 �. 61 ...1, CN177 (acres) CN 98 98 " C Soils D Soils 70 77 7a =...'y�XI �Fs. r,e on '98 CN(D.A. C) 8$ *�k �'-�r'1 u SUMMARY OF IMPERVIOUS AREAS FOR SDP 201900045 Impervious Area Breakdown: Sidewalks & Dumpster Pad 6,212 SF Pervious Pavers 4,700 SF Parking Lot Asphalt&Curb 50,140 SF Building 9,500 SF Total 70,552 SF e r / - el ,G ! if c a,x9 � � •+.r , r r7 i1i+•'rh; � •>• .:lid 1BWILDINC A 0& (g.500 SF) C)C o.. r J• t / I maim / ( if Jr / 1 / 1 DRAINAGE AREAS FOR SDP 201900045 —50 SCALE: 1" = 50' •ii F , R�... �f PHASE 2 MANAGED TURF CN FOR SDP 201900045 C A Soils B Soils C Solis D Solis Forest/Open Space — undisturbed protected r Area (acres) .asJ i_ . vlp. ':.,,_. • ..,,$X 4 1aS \\ a.vi' Qn ae ((�(�� k gam1SrS." w '° CN forest/open space or reforested land 30 55 70 77 Managed Turf -- disturbed, graded for yards or other turf to be mowed/managed Area (acres) „ r 39 61 , 74 (�ay $0 CN Impervious Cover Area (acres) s..l, p' 9$ „ ; E2�¢i: .,,_.a 98 a.aQ s`'.s 98. K.`.�Q� 98; CN CN(9A. B). y 1-year storm 2-year storm 10-year storm RVDeveloped (watershed -inch) with no Runoff Reduction* RVgeveloped (watershed -inch) with Runoff Reduction* Adjusted CN* V r 1 1 I 1 I / I I I � Z O S N O 0 N _ cc 4 5 Q M m M ZO Q O O z m n 5 W W O � 0 W O 0 zI Ca Cq � N .'A �D> m Q� 14 DW�II z �0 f�-1 py a F-- W a ri � � O N II S ZW�W�w O z g z M o o 2 O En z 0 Z ~O N O U O p 0 U Q U > U zl�-- IN Ito I� ILO i E-+ w E4 H w 15! U 00 di 0 z 0 �� w�IW �o w w �CQ H N 00 Zi W H 0 LO I—V1 S 1v` , Zolu IL W SHEET NO. -504 SHEEP 19 of 19