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HomeMy WebLinkAboutWPO201800077 Plan - VSMP 2022-06-153 0 m 0 0 0 0 OLD TRAIL VILLAGE -BLOCK 32 VIRGINIA STORMWATER MANAGEMENT (WPO) PLAN AMENDMENT 3 SITE DATA: TAX MAP PARCEL: 055E0-01-00-000A2 MARCH MOUNTAIN PROPERTIES LLC PARCEL AREA: 23.27 AC LIMITS OF DISTURBANCE: N/A - WITHIN APPROVED LIMITS OF WP0201800077 ZONING: NEIGHBORHOOD MODEL DISTRICT (NMD) OVERLAY DISTRICT: N/A MAGISTERIAL DISTRICT: WHITE HALL SOURCE OF BOUNDARY AND TOPOGRAPHY: BACKGROUND INFORMATION AND EXISTING CALCULATIONS SHOWN HEREIN WERE TAKEN FROM WP0201800077 AND SUB201800164 PLANS BY ROUDABUSH, GALE & ASSOCIATES, INC. AND APPROVED BY ALBEMARLE COUNTY ON 05/23/2019 AND 08/13/2019 RESPECTIVELY. TOPOGRAPHY WAS PROVIDED FROM ROUDABUSH AS -BUILT SURVEY FROM 2020. COUNTY OF ALBEMARLE 6 j Department of Community Development Construction Record Drawings (As -built) for VSMP The following is a list of information required on construction record drawings for stormwater facilities (reference Water Protection Ordinance 17-422). It is preferable that the construction record drawing be prepared by someone other than the designer. Please do not provide design drawings as construction record drawings. A. A signed and dated professional seal of the preparing engineer or surveyor. B. The name and address of the firm and individual preparing the drawings on the title sheet. C. The constructed location of all items associated with each facility, and the inspection records to verify proper dimensions, materials and installation. The items include, but are not limited to the following: 1. Inspection Records and photographs for pipe trenches and bedding, including underdrains. 2. Video Pipe Inspection for any pipes which are not accessible or viewable. 3. Updated Location with geo-coordinates of all facilities. 4. Verified Drainage Area maps for the drainage area treated, and for drainage to the facilities. 5. Current physical and topographic survey for all earthen structures. Ponds should include a survey of the pond bottom. Surveys should verify pond volumes are per design. Corrections may be required for alterations from the design. 6. Plants, location and type. 7. Plans and profiles for all culverts, Pipes, Risers, Weirs and Drainage Structures - Display the installed type of drainage structures, culvert/pipe size, weirs, materials, inlets or end treatment(s), inlet and outlet protection, alignment and invert elevations compared to design. 8. Computations: For significant deviations from design, provide sealed computations verifying that the as -built condition is equivalent or better than design. 9. Ditch Lines - Display the constructed location of all ditch lines and channels, including typical sections and linings. 10. Easements - Show all platted easements with dead book references labeled. Facilities and drainage must be within platted easements. Provide copies of recorded documents. 11. Guardrail, fences or other safety provisions - Display the constructed location of all safety provisions; fences, guardrail, including the type, length and applied end treatments, compared to design. 12. Material layers - biofilter media, stone layers, sand layers, keyways and cores must be verified as to material types and depths. Include inspection reports, boring or test pit reports and materials certifications. Biofilter media must be an approved state mix. 13. Access roads - show location of access roads, surface treatment, drainage, etc, as applicable. 14. Compaction reports are required to verify fill compaction in dams. 15. Manufacturers certifications for proprietary BMP's certifying proper installation and functioning. WP0201800077 COUNTY OF ALBEMARLE, VIRGINIA 04/05/2022 LAUREL HILLS ' C R O Z E T Crozet Elementary CROSSING School0 ORCHARD ACRES GRAYROCK s WAVLA e GRANTT a WAYLAND PARK Musictoday u WyG PRtl t BA RGAMIN PARK ° Crozet® Sturt Hill Sre � Jermana CaO Ra HVIa:'d 9ucp a. s REA PAR KSIOE a°a VILLAGE Claudius Crozet ParkQ enrRy Crozet Park o AF ards & Pool _- PARK VIEW e �� The'LTddgeat Old Trall9 �w -., BROOKWOOD d OldTnilG:, rime r� OLD TRAIi \ - a`a W ;,'WHITE OAKS , SITE The SummitQ N T A I N LOCATION Apartment Homes � ' Q i T FARMS � 0rarrck Crozet -Meadows �/ CO 0 Piedmont Baptist Church .eS Rrownsvllle kPsh OaVTomplke= �_- MOUNTAIN Fxron- F°c r & Oak igrap� 9 Pro Re Nat Grewr r 9- ®bp VIEW BROWNSVILLE = Willow EqulneQ// Albemarle HEIGHTS O Western RA Yancey Lumber High School '. Corporalion Go le Ins] FOREST GLEN EMERALD FOREST VICINITY MAP 111=10001 DEVELOPER: MARCH MOUNTAIN PROPERTIES LLC 1005 HEATHERCROFT CIRCLE SUITE 100 CROZET, VA 22932 CONTACT: DAVE BROCKMAN TELEPHONE: (702) 985-9088 EMAIL: DAVE@OLDTRAILVILLAGE.COM ENGINEER OF RECORD: TIMMONS GROUP 608 PRESTON AVENUE, SUITE 200 CHARLOTTESVILLE, VA 22903 CONTACT: JEREMY FOX, P.E. TELEPHONE: (434) 327-5382 EMAIL: JEREMY.FOX@TIMMONS.COM Sheet List Table Sheet Number Sheet Title C0.0 COVER C1.1 APPROVED BMP CONVERSION NOTES C1.2 APPROVED BMP CONVERSION PROFILE C2.0 STORMWATER MANAGEMENT NOTES & DETAILS C2.1 STORMWATER MANAGEMENT PLAN & CALCULATIONS NUMBER OF SHEETS = 5 AMENDMENT #3 NARRATIVE: PER APPROVED PLAN, WP0201800077 DATED 05/23/2019, A BIORETENTION FACILITY IN CONJUNCTION WITH AN EXTENDED DETENTION FACILITY WAS UTILIZED TO SATISFY WATER QUALITY AND WATER QUANTITY. IN THIS AMENDMENT, A GRASS CHANNEL WILL BE ADDED BETWEEN THE CURRENT PIPE OUTFALL AND PROPOSED BIORETENTION FACILITY. THE IMPLEMENTATION OF A GRASS CHANNEL PROVIDES ADDITIONAL TREATMENT AS WELL AS RUNOFF REDUCTION TO THE DOWNSTREAM BIOFILTER AND EXTENDED DETENTION. SUBSEQUENTLY, THE BIORETENTION FACILITY HAS DECREASED IN SIZE FROM THE ORIGINAL APPROVED PLAN WITH THIS DESIGN. THE 2-YEAR AND 10-YEAR STORMS HAVE BEEN ROUTED VIA THE NEW FACILITIES AND REMAIN IN COMPLIANCE WITH THE APPROVED PLAN. SEQUENCE OF CONSTRUCTION AND NOTES FOR PROPOSED AMENDMENT 1. CONTRACTOR SHALL VERIFY EXISTING SILT FENCE IS INTACT AND FULLY FUNCTIONAL PRIOR TO ANY SWM CONVERSION OPERATIONS. 2. CONTRACTOR SHALL INSTALL NEW SILT FENCE AS NEEDED TO ACHIEVE PROPER DOWNGRADIENT PROTECTION FROM SEDIMENT RUNOFF. 3. EXISTING RIP -RAP OUTLET PROTECTION AT THE PIPE OUTFALL UPSTREAM OF THE PROPOSED GRASS CHANNEL SHALL BE SALVAGED AND REUSED TO ACCOMMODATE THE NEWLY SHAPED OUTLET INTO THE GRASS CHANNEL. 4. GRASS CHANNEL SHOULD BE GRADED IN FROM THE EXISTING PIPE OUTFALL TO THE BIOFILTER FACILITY BASED ON DESIGN SECTION SHOWN HEREIN. 5. EXISTING AREA FOR THE BIOFILTER LOCATION SHALL BE EXCAVATED AND RESHAPED TO DESIGN GRADES SHOWN HEREON. 6. ALL ELEVATIONS AND INVERTS SHALL ADHERE TO THE PROPOSED DESIGN HEREIN TO ENSURE WATER QUALITY CALCULATIONS ARE MET. 7. UPON COMPLETION OF SWM CONVERSION, THE SITE AREAS SHOULD BE SEEDED AND FULLY STABILIZED WITH GROUND COVER NOTED HEREON. SIGNATURE PANEL: APPROVAL DATE DEPARTMENT OF COMMUNITY DEVELOPMENT: ENGINEERING vpN"I r, 0 Gr IEREMY L. FOX y Lie. No. 60786 06/ W 22 jt% ram N Z 0 f LM Z Z w O H O a U CY- Ln o O Z U O w a- LU LU tlJ Cr_' DATE 04/05/2022 DRAWN BY J. FOX DESIGNED BY J. FOX CHECKED BY C. SHIFFLETT SCALE N.A. LU 0 z LU Q 0 � a Z c� N > W M J > 0 U LU Om J Q J w co O � z LU U r n U V Q J J H� J LL H 0 J r•1 JOB NO. 47010 SHEET NO. C0.0 rn L NOTE: THIS SHEET IS FOR INFORMATIONAL S-1 EXISTING RETENTION FACILITY :- � I. .. VA OCR SWPP L. .._._. ._... -. I ..... VA DCR SWPP ' VADCRanceBasedWaterquautycalculatlonProcadui• i srnArorcz .. ; . l.... .. 1 ... .. !.. .. i _. . _ , . ; .. ... { � � i FF-(RR=hy.,.,)xWO (lqumitioni� _ - - DATED 5 21 PURPOSES �M 2019 a7 a o Performance Based Water 4ualitlr Calculation Procedure � i i GPI nn eb riY,rora,tom(P(etripK:e«} _ .. ' ..._ , _ _..,_ ._..._.. a� - '! . �: �aatar,arkpo. 2M r� BY ROUDABU GA�E & A� OC.PLANINC •� ..... .. .. .... i (._..-_-__. ._.. ' ..... .... _ atx sx ; -��I where. � ed. I v e&'iciem -a.._ F , 'Projlact_pTV�leeh 311 WPD26tfij10Gtt}(BltihapPBE,xtegiQaQi�kantfun)..� Loci AlbaniaCa,"'.. -• ::.' ., -'' .. Date: y22/20te&33 �: �, t' ` '` �' + �. l 1 _ _,____.., ..� _., -.,.__ .RR..__ _;�11WerRram[Wal rsrna,ra+Pat(ponods P.=r.Y=�)_. .. ..-_.:�.. __' _ __._ ._ _. _...._ I I i � - ! laiivepn-developntetrt6aralplwsphorottsloadCstetigrtS21(1WtaN9s ) i a • � � IPusl � ,irC I � I3uemn[YofSdmda,2 ariaXia: tnnncaladaGou lxattdwu STBP ralln�.s#. WnrkslXwt l: i lhhe � sWks slaax. www. .nai.:. . ,,. r, a r h �'"a OM ., ..� ... Worksheet No. t � �,. I . , .. ... - .. � i .... ... .. � . , .. i ... .. FrF - t.eo ! 606 xtl)Q= 3z% ! h='•J. �tx ", r I I I in,:,rxi tsv. a[i1 roan a A" sae• Jaar �t,• 1 y g W a De4!imine tfie, awble- and the post -developed im - wwver . _. :_ . __.I_ I ,. __•pp _ .., ..-hertrlo r .__IN!?s_tl..._... ._ ___ 1 _ _ __ _ - 7.86CI tttcres 1 -_ ._.-. -___.. -_____ _ .. _ .. ... _ ..- ;_ I- -- - _ I_.... ' ..._. _ _ - .._ -. _ ._. I :...,_ ._._.. _ ..._ ..., i i FA. _.. h ..- ..._ ... ._ :. ..., - .. 1_ ._. Ie4iaun¢"_ ink IsJr96 arm - _ ... 1 ' I _._.. V_Se(lCtHMPSs)ff0111'l'ehk S-l4 and locate on 91ke. __. _;.. .. _. .. ..._ ._._ __.. _ ... _ .. .. 1 CURRENTLY IN a_ I- PLACE? NO Drainage Itrrper ioua r i i ( I ! '. �+• �- - •!•- ' stirs- aWw .ww' seat- �aYRx. area +�iW� x. a. ,.r x Z_ �[� (� 2 f6 V O EO . Prrat-deveMpment impervmoa cover: ... - .. i.... . ...... :.................. .. . .. ..:. ' . .. ... ,. .... 3 (.. " •sinNalaGs _ ,.. '�� : ' 41578.E af. m 0.955 !acres _ .... .. ........ I _ _ ' :..... .. _ .. ... _ .. ,- .. .. .. ...1. ' ..parlav,�_lot= .. "'��: { ' af. m ' 0.000 acres .. ... ! .,.. ._ _. 1_. ... .. ....._._..,.. � .... _. ..1 I .,. .. .... .' T i fdf ' 'Area (at) ;Area (af.)ir .. .....I .. .. .. .i . .. .... i � I. , I• Detcrndae [tr [eletivc p,eaea•cwpmm Imw (lt„ ). 1 BMP]; .,`RakitOdn � : )•6!) � � :)'3:a23t)1 � -. gBt36: '. BMPA i ., .... ... �� _ _ .. i ! �alpe .._ ( ...-.. .. ._. ... .. - ___..._ aaxdan,Ez I rXoye Cowl. - .__.. ....... .,_ _._ � _.. ._. _. I _... _ _. .... ( i Il,p,n,ma.et'tOOS +(Q(x39x 4vnrjlxAx22a (EgwrloaSLel`.. ; I �-iSOQDSC._�.'�„( � i -Nara a[llgi +ttWa •iwi► 7 r ... '. to 7' .s1a yl - � I.. w � ''ww Q J .��' 0.ti55 !acres - i ._.-....;.. .._-.,._ _.._<.._ ..a_-..._., 1. _._,_ _ 3. Dabor�Rethe I1tAantload the d s ; .. .. .( ..i t i . .. .. _.....,. .ip �.�I. }. _ ... ..,. ,- ..i.. ... -., ..... ... 1. , .i _.,r 'vo ;f - iN:l(F A wRli' �� .'�: VJ J J ti �i - - ..., driyewpys & swlk= tt�,, %- 7_ __ r. « Q. acres 7..- :. .. .... 1 ' . na ybva brat om (uxd mde _..... wEn 4-w ,,il m[ PM LGww aBnap> x (w P ram) J .... �. �.. J,.. �_ Ilm+asicmpo uq.=:-dw,nYnL nu:hni , 'r }, r., iI4 .Ja. '::..'.� V.. i' •(t .Jti. ft �, LLU :C ODa re :. .... sf. m 0. rats ... .... :.... .. ... .. ' , � ... _D 000 re3. .. .. .. _ .. ..... }� _... _ ...__ .. _ . .... _ _ .... ... .. _ _ .. .. ........ . - (( 09 x 4jq J x Riir x 2.28 gaatina 5-23) - - - - - - - ..... ... ..... .e. _..._ ... ......_ _ .. .... _. _. _. .. ... ..I ... .... A = irytlieahlamm (acrae}�.. ILgtp 0.05+(0.0 ) (E is r <e e• ?yen•... 4j\ r JNN• '...-`,wra. W • ... ._.... ..'__.. _. _.1_..'-___.. _.. I_.. ... _..._.. ........ ... :. ....._......!. _.- ...__. ....._.E ...... .. _ - L.. _... = i - .0i+0oWx ... .096 : » X -..10.ae"%2�•i_. :where: 1dmr lrelativeposadevelnpmerttntalphoapMroraloadert[iringpropasedHMP_(Roudstrer.}?eat)._... fi* IN. �I.... ... .. _ •,:,„ - .uL tee. •:: .J� - OO G ................. ... .. Total = ; .. .... ti676&g642 s.F.m 2039 scree �- ... _. .._ ..,... . !..._._., _ _� . - �. ..... ... � , - � ..._._._... _ - .-.._. -,..... -. ..._ .._.......____._ .._._ .._.._....______....-,--- -,- _,__ ,.Iw.. __ __..___ "I' _ .. _.. ..._ .. _ --.. ........ .._.. .t*..tt mpttviouscoverloproposedBMP ( rocMexprcasedinwiwlertvnliers} t ....- IEr .-.-...__. ....1...._, .. ._.. ... -- -- -- ..._ _ .(_!. f.ta veer I IusiP - Post-devclopmcMpereent t __ . _ y t v !drainage area. to proposed (_ �.z a+et: (oas+(o.uos.),,.,,,.,�]xAxz.a (&PwannL16) i � ! A i . , ....3�91aLL' T � i� 1 , � - - ... -. .. --- ..._ ..,.. ..... .. ._ .. ... .----. ._, .- -� - - - --.....f.. ,a . rr1a. ...� -i xr.. "' yyy, � Y .ah -` ..: .vl: -- Q 4Z M C\I 1•+•i Z0 =04 _IEe[1=(tomlpost-developmetditrparvtomcwtt+A)x1W= � _.. _i.. ... .. ... ... F .. . I i - ... - .. � I 04 ' .._ _..._..._._-____._.;... _....--._..._.. _.._.__. ._._ _..,..,.,,..._.._.... _.._:-_-.. _.1.._._... ... ..__..._._.-i__.._.. ._j._.. „:__.. „...._..._..i.,-__. _-._...� . _ ....._..._...-- - . .._ i (r,•+ralas) - ffi8 impe,vb•t wren ! Ste :AtMrm6re tlw average land pvarc•ndfaon er.the szte.._..._.___._. D•ad!�'- ...-._ '._.___._. : ..._....._. ..-'- _... _ - ..- .. ..._.__. .. _. -- - ... .... wltae am:.m([attdve rare axal rcxa toed( unrkt( ) : " upmzn pJbspao .Jw . l>wrYa•'. I . I � t•uxr, :a 0,05 + 0.009 x 26% i)1.. x _ 7.88 x 2.26 ' I !...... .. ; - . lam . _. .......... .... .. ...... ... ..... . .� . ... (..... _ 1_ ......... ,,... ._. { ....... .. . ..... . .... �s:,a��a.X«r..rl.a>u„Ibs.u.rl,..w.lmrwm�r=N.-nxwe.:.:•.•v:�-nd:.ea,,.-,e.v I' .. ._...- in+.XrMI. ,....... ... _ .., .. _. ... ... .[.... _4 ... ....,,. ... ... .,; � -Pow,ds _ r `+i'• � N£'«+JEQ �(�RF:?'FtJTIP.N �,.tiN � r., "a" ..Id 4 .a., `�,,,� y' Q d` M Qom, ...' .. . _. I _I -_ I 5.06,.. .. ; . .... .. ... ..... .. _ _. ._ - ..... _ ....., - - .. i .... I ..._. A 'al7aicahk area (ecnw) I I 1 -a.eaGc W:ti Av man laud nvrrcortdifionR.._ _.._l: I I ' ! if locality has determined lard cover Gondihrna for irdl vid,al watersheds within its J t_.....__. -... .h .., ._ „ ._.. .,.. _.... .... .... ....... ... .... ......! . ..}.. ._ .. r .... _ ..... : .. � I ..... � 1. .i ... i } -. ;4. Calculate the pollraari load,remo�rcd-by.t}e-proposed f3M1?(s):. .�. .. ... _ _ ... ! ..._ _ . -t ..-. _ .-.. Lp.e+:.o�`La05+(o.lxJNx lave » % : to.se ! .zm ! J ..... r '... '.' I i = tea pwW{,peryear ! s �. . - � I , i)Lif+iGfhit-HATEQ TURF CO'ttEfl Q1LL \ �� � JU[ladi4"LI011, the the Watershed Specific value determined by the locality as wwatershed. I I �. _ . .. , ... ' .. .. .. .... - .. .. . I - tt+3FLi3tN : (A } rwaali�a 4 W LO Iwnpsied �/a :. i ... .. '.. .. I I �. i .. ... .. ... n ..I I ()@wrynise, llv_Chesepeake 13ay defeulk ' �A• [... I .. -. f . ( _ _._ .... I-remnaE__.+f41UP x LUNY _ ,�F.f�Y8k10n ll2i) .___ _ ._ .. .... .. .. ..._ ._.._.. .(_. .. _.__-__I _ .OebOtl(0¢t1YC.RadNC peat-aCY010PmeN [AllntaN bai (1�as�. .. .. .. h-' I Iff : I .... '.. I' ' PflEMF-A.TMENT 4 FU`NG`Itdfar ASflEGIJIRF.A � Q r^ CO ( O R value:... uge .. _. , . _ .... � ...... .,,. ... .. .. .. ..: .....I .. I laa[eaiae !16°/a ! ! i -, . ,... _ ._ .. ._ _. _ ... 1_ _ _ _...__.__.. ._.. , _... _._ -._ _. _ii .. ...... .. .... .. ... - � i .. ..lwy - (a.rJs-Ct.atvx li,.a) x a xzzx (EiluMie•s•R).. .... I ' . _ ... .. .. ixhrn:l.®„.,,,,{x?st-deyelnpmerttnmlpFewpinrnuslnadre_naivedtrypro,(rosedH�IP(Lxnuldslxt}=) .- i .. i _ . , .i. .. _ .. i i .I. .. •(llumdsper , M � Z r � O n ;_ .. _..._.:._,...... .. . ........ ... ....._, l._ - Ih:ea rerimval effinel ofHMP mtleCl ... .. .. .i� .. H M 1Cy (mgxesud .form} i u. ,�. ly,- _.. navepwl-tMel veer)j �tr,IP - i� - - � !bW PhItglMmxLv Toad. .. -... ... .. .. &'vfP, E (. ) f ( st,� 1 , .... � 'Lr � W b- Ix a Glad- 16% I i - � ._._...... .,. _,_.... _..___._....-._,..--�. ._.._.-- -- .............._....___....__._....-_ ! Lratr = relative t-dovel PoYat s ais load scd o115.23 s ... rA Inpav[ous eaves svaJ mwaWc rnaaxre _ .. --.�_,..__._._...._,_....,-_-..:._.I�_.,.__�_P�.,...----...ru�'"fs.��..._...__.._m�.._,_._ P� l�.x�'.._..... _ ;:........ _ ..... ' �Y,.= .}P�:�. fry. ) � t pt .�. r. I ;.. d.. ..:,� Ii A- rppicwLle xreu (pad 3.30 Pounds year removed I E ... .. .. ... i. t ... �. .. .. 0 X I . a.. , �Lrm,.d,aaavmi _._ .. � ,. ,..... .. ...... ... ... _.. ..... ... .. i.,... ,... .... =}nos+Qoo9x ssx � �))��% j +a3B : %2za 1 r� V Detenrdile the etdffii i erviolu eovtt ofitte level meet site if .tRrlt. .. ._.. ... I ! ..-._...._......._J._... '.. .... ..._ _ .. -.,. .og '!Jp .. .. ... . ...... -oP `I ........pro .._ . .. .... .. ._ . .. ., ..t . .... t... , _- :..._.__..:. _ . .._. _.._... .......... _..__..._ _r. __ __ ,i. _,._..._._._. . . _. _...-.... _.._ ..._._,._ _.._- 'iPre•deveb )m rviommver. pment _ pe L..-._ .. (... ... .. , !.. ,..I ... .... .>.-.:-...af. or O.OW acres i ; .. ...._. .. .- _.. _ ._. .... .. 1 ......_L..-_....._-'...._....•.__i.._._....._......__,._�_.._...--_I__....._... ..__......._.........._ ......_tz.ey IS --- - - ' - - - i I -- - .. .i._. �' _ -. I - -. .... L ... _ .... _. .. --_...._,. .;_._._-. ..pfl _ _h3:_._ � �`.. ! .__ .. _. __!_..._. _ _�' Deteminetaemlrtk'apolMNaorremo!drcgla,euem(RA}. '.J... J } Calculate the tote( llu ant load re,novp4 the 6M a -- I ._.. _ j ...._...., ......................... ..... .... . . .. ... .__..- . ._. .. ........... .. ..... . _.�.... .- ..1. ._ ..... _....... t_ ..._..._ ..... _.............. ... .....__. .. .. ..._ ... .... .. .... . .. .... .. .. _... t it-,r�l•e'[Ilal, = Lraa..r.'auP1 i[.:,,.,aanun+L,a,xl,w:w.tri+...(Etlrti0a S23} 1... .(0.9x { j..._. AD6tTIDFtl?tL ADDITIONAL PJNDINfa _ ... _. 1?C161EJlN�i AFiF•A AREA C1 III EL EL .. .. ._ strut ... _..... ..... .... ... .. .....}._......._. .... .. ._. .. ... ... .',. ._..... ki lof ::..::': ;:. ri:.'..':' : :' i •:: af. m .. L- D;000 .. iaeres. __.. ._..._. .... _... ..__ ... _.-_ _. ... . __... _.__...,-P ...nS ..__ .__ ..,.... _... _,....,,. ,.,,.... ..;._ _. .. _ � ..... ...-er- ,..w ._ ..ti_�_ .... .. ._ .I....... ... .. ... .. ... .._. ._..._ _... .. ... ..,. _.._......,._ ........... .... _. ......... ...._.. ... .... ..-.. .. .. ..._... .. ..._....`tr+....._.!x.._.._.n.._.....-...... ..�. ..... ..„ .. .. ... _.. ..... _ ... ....... ......_. _,......_ - I ..---- _-._._. ._.. __..- _ _ _ _-- 1. _ ._.. _ _ - _-_� __ _ �''- ..._kma'to[al ._. ..__,. ... .. fl.ao 'ponats.PeLL00r_ p.... '. - cQLv�r=falt'�1'�D rSN_:'Rt7E1VF1fZN HECi SU E. EFa INFL OW AND '� $FAG 'AR s.f.m I roadwa = ::,':....:.�. .. '.•.. -: _.. __..:... 0.000_ -,acres ... .... .......... .... .. ... .._... � tltantlliad realoved by PnYpoaed lJMPs (Pa1°!laP�. ..._ ...... ...... .._....) where: ) ...... ........ _a•' .. .. ., ,_. .... .... .__.. ...._ .,.... ._..__....._.. _ PRETREATMENT VISIONS other. >.... _ s.r. m 0.000 !acres i 1 , , . . ... .. _... .. :.• , , . .'. s.f. m ! 0.000 �aces ! � • ; RR ' I _. .. ... .. _ ...... _ . }rollWmu load removed bYlxopoaed HMP No. I, Et)Isttiw 5-24 � _.� 1 RY= 12S ' ry M1Li1-CHLAYF3i 6Taaa ncr': 1hfLON1 ' jj ..._... _ `_.. ' I• 0.000 acres ..... -_ .- . __.4.. .. ., �_._. .,_. _ J _,. . �, - ... ... .._ .. _ ................ .. _ .i .... _ .,... .. , .p ' ._.. .. ._.._ 1yXaavada,d= .polls.dent load removedb�.ProPasedHMPNo.2,EtI1}ation3-..a - -- ---.._..,RR. ' I(I (�' PRETREATMENT COUNTY COMMENTS , ! i..---.. _ __._ •_ ._._._...�.- � ---. _ ... -- --- - --'-'-I"-..--'L- _.-.i-" _.__-.-- ...... ... } .. . � . . _. 1Law,ea„p,ry-. Pollutant load removed by proposed HMO No. 3, Fg1aAm5-24 µj. i ! .. l ......_ .. .... ._._,Use ma rp val[x�i, i_ .t ..:.� _ ._ ... .. _. .... .. LiEATAJLC-QRL'}RTIt:Wui SURFACE Feb 15, 2019 0149 Total ..,..._. �. ---- - -Oaf. or 0.000 •- _i!...... - - ----- -- j--._..._! ._._ _ ...... .__ . _ .-.. 3 . .... - ... . _ _ , "Vr .-.. i .... I_-i.. .. ... .... ... ... _. _ ... ... -.. _ .__. .. _ I }. ... t><aaPray..auy1 Pfxads Per year removed t - - .. ELEV4?Tfpta �m COUNTY Ap 'ir I COMMENTS 2019NTS I"tea°s=(total crosfiiig torperviaa cover+A}x 100 =._........_....... ._._ .__'. _., ..__..-.1 .. ! __-i. , - . J 1 ' I 1 I ... _ _ .... _ . ..... ... ..... - ... L .. _.. - .(... _. -J "-'I „i.ix[ciar dlcf[r_glarca PalLmemrcomaL dCrma)cy femur son.; .I _ _ - -. .. .. ! ... ... .. I ._ _ .. _... � . ... } . ......... - . , .. . }.. ._ ...., . i............ 1 . .. .. I IG. Vaulty l.0>11phallCe: itaruwsa'aNlzxrt. I ItPF=(RR+f.•„)%100' tEglafim 5-22) i ! i. _ I - .::R (rE_---- _ c. , �y ,' .� s l-°( ,. �r .'•.•.-:,,.` ., a,' -� e4.e d r FOR APPROVAL el• : Ilia area slaiutd be the same u teal in STEP 1. r...... _........ ....... -:-. _ . .....! .. .... _ _....... .... . Determine the appnoprlate deyelupmeat sitaatma i I � .,.,._ _.._._ .... _ .. ._._ .. ._.- - , -_--- - --.� - -- -. _ . ,_ _ _ -._.._._ . , . I . . i r� - -; •- _ oral 1.,' I 1 3.30 Ta61 Founds r rem I fi=!'yea ! ... _._... _I - 1 Req'd Hk 1.60 Told Pound• per year removed: �._ ... .... ] ........ wtixrr..,Isayirul p,talX+•t nmpatd tl0u_isuy ' - � - - .. I : -` r o l . , ti-lUA,RkE . _ - 61. ,x.. ;:_.& '7-� ,'�A� ' LEVEL t MNN, Lir�_r I " 'J � May 21, 2019 ., _ _. .. _ . - _,. _ .... -_ ...._,.. _ .._.. ._ .. _ . t . _ . _. (.. ; ' ' ...... � : .. The site inforgmtion detcrmiilCd in STEP I land STEP 2pronde Crl[>I•j}ImfatrwNon W,determine Ole aPPCeP!'Jato .._ ! _ _ . ... ..... _ . . _ .... _ - ] .�_ ... .. '� M`lllum!_smnvxtZegnv�e,u (putavlsperr'�)'. .�.. ' lD 17emoval Irate Exceeded 1 'J iret •.e ,a�.t:-va c,i r: al,s-n rw�+ -a r � - .. ,. ..l a, i opnclrtto pl 'apinnna kad, 1'QR ) J�( 'eaa' _ i_ _ ?.� �[uEL :I Mlevj --•j .r�} 1 � development siltation older which the pafornnrree entrna wLtl appl ry, ('hock (.)the approQrlatc devd[�mern situNhoa as fotlovra:�_-, _._ :.. ,... ._..,, _._,..,._ .__ I t YEF zaa r 1an .,so- ! . _.... ... .. .. ... .. .; ... .. .... _ _ -., � 6 .. ,�.. I tIP �� ....L _. ......... _„__._. __-, - -. ,--- ._._.._.._ _.+.. ._.. _ .....� Sitaatioal: iTkawG�tstsoftaodtievet -� •tvhrrethe-- _�• pervert' i[xacovtt(baml)isltxssthen.ot ' 2. SdwtJ3MP(xt LamTahle 3-I; �ilur:atc uo lLoslo 5-13 BIOFILTER 8tEXTENDED DETENTION FACILTY _ �� - 3 .._4LEVEL_`, ,.-,. '= � - I I � � � . i � to rite ay _ .land cover_Gmdlien (Iwskorehed�} emu the proposad,.iniprm�trnta w,ll create _a. total per - ...... .. ... .. IP9!'� .. . , .. : ._.!�ernouscwer¢post},wlechislessibsn,arequalWdvc •,laud eover.eondih�(I-watershed-}. ...._.. _, _....... .. ..... _ } ,.__. _ - • False Ipunt 26% SI,,,,,,•}„ar ,6% ; 1 I .. ._..... ..... _- r., _ ,. ,, rip• r l%> ( )_.. I IVA DCR SWPP.. . ' ..__... _ .- .. -- '- • •-- - -- - - - --- -._ , _._.. _..... ., amp r `el lu. ;; va "s r n,z IIiPR .. . I ... I ..... , .--�--._.. .--�--._._._ ___. .. ..._..____...._ _._ }. ..i_ - - 1 'i ;PertO/R1311Ce Based Water Qualli)/ CaICUIatIOn Procedure, .. .! I I =2 0 2s` �'.. � :2.rzeo egpa � _ ' ...I _.. edW :. .... __.... _... ., .... ..... -. _--. . ; .... , , .. amra: ' ' ahv,c i 1 L . . ...: � � ... ...... .. .. .. is .i. tion6a,piori) � i T - ! �� I i= •�' `I^-i ! �-... �! (_ "' ••`: :�. � . AlllltJ.OL,MVBTt?BE STONE SUMP t7AYLIGHTE'L+ (QPEN OPL4DED) ... .. .. .. .....�.._........._..- .. .. _........ .. .. _.-._..... __.. ' _... ! .. frees't0(@llityCrlcul _ ] 1 - - BMPA -._ _ry._ � -.. q••. .. .--_• _ I 1. ........ y amps. � - � _ aePE •� � I � 1 , � � .. Yss Situation 2; j-This crosists of land ticvelopnielit where 91e existing percent impervious cover (f;y,te„z) Is Sss than a eay61 yes � ' ttvtlxaveragelaudGuvercolxlittun(Iwateiyhed)�o�ltlx.prupctseeiiit$rovemermwill[,zeateatuTal_penent.._....... :Loceely:.. �Aaterrnite ¢qt.:. .: ' .' :. „< ; • I -2(22I201e:@:2,6'� :,: r '� ���� ... ! t ..._ I. ! II Imo'. ., � � 3.°N�'°°.ale�Ltlm�.LF.a�wrwa�J?<oPaa:dl�mfsx � .i _ ; .. .. � .. .. ... , �� } , CONTOURS .... __ .. .. Warkah }w _ _-.. _ i _ _.. ..,.....!...__._�, ' ,Jmpem�covor,(Lpost}wiachis catcrdnnti�larrleoverco_!drpon(Iwsdershcdl �-, ! True 151^!g+�^_ 1� ___.___I .� ..... ... , r . _..- - t L. LaXr - tons+roan X (aa•)1 xA� .x z. a cEgn6X,5 zA j .I i and thepost-developedmpervrou•eover(lpwt). I I I I_.._.. Figure 9.5. Typical Detail of Bioretention with Additions! Surface Ponding 2 FOOT ... _..._.._ 1..... ...'Stan„_Joeternlnetheappiwblgmm y_..._.. ' I- _ _. �'!ralaiw 1 ! lard , .--' �_._.-_.°'..___...... .,. __....-._. ._.._i.___`. ...._....-.__....__ __..... __.... .. ._- ._- ......._ 16% - _. ;-.PP ( )....I_. mint load Bb1P )i w,Pm�opniUMP tprn:enesr_sad is whulc,a,mbe[sl �.._ 'A livable arcs A = 452t52-8 sf Gr 103� !acres .-�... wl>y,c: Jn, � True l t 28% >1„,py '_ _ _.-:..__ .i -_--- -_,. � : r t � � :........... .... .. .. i .. .. i. .,... .. .. .. .. .. ... .. ........ . .. . . .. _ .. . .. ..__....---..._..__..„_.._'.7....!r1'.-.1-`�aPmm..imperi+wswver a - � � � IAp,rmn• - Idreva>c rce u fxopoacd BMP (eorr:Y) I- i _:Post-deveMpme tinipervioaec(rver. j ... .. .... .. .... _ .. ...... .. i. .. .. .... ._ i.. ... DATE _ _ ....'_. ..... ._.-.......___. ...._..------t ..._.... - ! alrl,ltdaes - T:.n;. y:;.%::''..'..:'-s:.:C�.v:": 0.1100 'acres I ..i1n 'l Pb °SituatbR3: Thiacaaistsoflanddevdgpmtxdwlaaa81c0�dscngperccrai ouscovm la: )ts ._...__._....__..__.....___.._.,__,...._._._."'._.._..._-.-...(-_.""_4..._. _._. .-__..... .. .The av lard cover..mm-}mnn Lwatersf[ed?_..... .._ __ _ I I _._.-.,._. .._..._... _- _.. .. _,. _._..elate.. ..____. .___-___.-_...-._. ....__ N`sisc i t„Iws� > 4wnra 16% J ..._. _. .. .. .. .. ... .... .... .. L_ _ .:.. .. .- .)...,.. ...._ .....-...�.....: ...::.::_.. ,.._.....' - ._ .7 .._....._. _......,.,----... .......;.c..:.. ,,.. ._... _... ..... .. .. _ _ set - -0.05. 0.009 %,, TO% !)J % :z27a :parlonglo[ ...': .:> aL a .. 5;500.. .scree . .. _ ... .. .... .. a ,x..L. .err ! r __ ...� _ _._ � ._ . ... -.:. ;` ..L. ..i _ .. .. ... ..$ h_ t�[_,.. ._ .. .... ..... 0.000 'Roes I I 1 ..i . .icy nos-(0.909x ! a 1�11 % I an x2� �._. l .. l .. � pi � ! i' t :roadway I _ .. .._ .. ._ -. _ ` .. r + CaHAii[3EU 'a.. ! IHt f R1=A1 ilrltN i L ! _..,.._,.._..... .._..._...,..__... _. _ .1_.___«._... _._..__.._ ..-. ._._-+.,..... - __.` 4 1 tltte etnsh cam i vious raver 1 is sened an ..�. a ft w the r,•m Sitwdm Tinscoratstso ttnddeve .n$I�r ( liY _.........__.._. _ .... _ ._.... _... -- - i , af.q ° _ --_ - ---- - - --1.. _- - - - -- t- -- - I. - - - - - - - .. - I I •- i_ ..I -1208 'pomlaperynxc I- i . <...,... .. ....,, ._.i._._...__F._ .; ._. i ... ! I _-...--.----- `• -- _ ----__.,._........: ...... �.�.,.,r�: 'I L... .... __.....-- . - , .. ;�, :;.::-:''�; , y af. m 0.000 ,acres i .. ,.-........_ . ::.. � FILTER STPUP SCALE Icxlsti. tRormvvatcrtliatagcrrw'riBM, s)dlataddrepscswaterq!alrtg:.. __. i.........! .. _. _...: .. .._ ._ .l. __. ".H ._._._ ...__..__ ... .... .� - ; ,.... .. �-.. ... ..... .. .. .. .. .. _ .... .. O.W X 220 i 1 .1 i _ ... ....;I•IrsPt.-Loos...(o...-.. ,. _ I..... ; ..... ..... i.. .. .'.{ ���' �.... ... _I.• _ .. .... I ... .. .. .. ... .i � � I r!- i scree ..<L� ._,....--_-.._.._......_ � ,.......:... 29B5a0.aLm 5.500 _ ,! I i. .!,, .,-U.0s-...W9x .!.. ..-,... i :. 'Iota -- ' .... ... ................ ...I ..... .._ .......... .. ... .. .! ... _ .. ... .. I . ... ... ., ... ...... ... ..... . ,....... _ , _ , ...... .. . 1 :9Littl FLUW ati � itrria for levels 3numion l :if the scd leY0I0 meets The Cl .�_ ..... .. __..... .. ... _...,_.._.__.. ......_....,__.._. _____.._-_-_..... _.._ :__....-....__._propo -i • - considered to he the HMP and tt[i Ntsam removal Is r red ' thanihelnademl level tnentls_ .. 1fO._,..._.___ ._.__._. e9u!_..,..-_.__...,_,.�,.. .........___.-.__._._.._ :............_..�.............._..___.iY..___oJL.. . _ ._.._.._..�.. __._._.,..__.._._. _. _. _ .. ---. t Thecacul Procedure _......,_gPgTerd....__._._...__ ..:.._ _.. . l 8nOr1 OCel1Ae LOT $11O8tI0n l e tare. Ifdie scd leYet trleetl lure Cr1tCn8 for (leYO,lO,p.(11errl .. _ �(.. _... ....-- .. _....... .. I ) : X.. 0.0) : x220 •.. } 0a } ...... J. ... ...... .....� ... .!- ..... ... .. .. 1..__- ...._.... _.,. .. . I ..-.....---- i...__. ._......._...._.. ._.. _ I ..... .. .: .. .. - ...._ � - .... ... I .. .i . ' i . 1 -' ! lira' petals p� eat '� .. tl =(total t cover+A x 1W= 63% I t I ! --- 1 � i _...,.,..._ _.... ,.,. _.__. _.__ ..-,__ ,_. , :__.-.. _..:.. L'!•.L.__-._.'dC1,'-E1WfiCI1�1(17pk9y?oiB ._..__--.). .. .-__..........�. t. _. _. _.._..-r_. ..... ...._.y I t : ' I I , � _. -. . ...... ...... J ..... = nos- 0.tal9x Ois x aro . Xzm I L.... .... !.. _ , ..:.......-....... .:._ .. _... ... ....: ........ _ ... jlOn I ( I II- r ) HI-LF(FAI MI -MI _.y _ 1•I 7 tXii-7VUEU FtLTRATt9N -;;,,,- ..ti e;( .-.... _ �.-�► , 't.�rf DETENTION S7 b �, .n. STORt\GE J .i '. F I4yT $ Q. D TRP 4 Gn Iliad• wmkahee6 .311uahmis2 3 Gr4 Ilan ._.__?ps........ .......FPF..Pp7.___......... ____........ ._.... .....,.._._. I .... ---.-__..._...,.,.. ..... .._..77�� _ _. _. _. .....: ......1._......_...... ........ ._!. -. ! 1 - � .._ ...._ ... I :Determine the average lard coverwntrrtt•n (I,,, 9.0 It existing ilupervimrs coverl4aal .. - � _ 1 .. ......... ... .... ....... _... .. .-. trnbal) .... ... _ ..... - ��.�. ._ .. .i O.W ipaadap¢yea � ' l 1 __ i .. __... . ' ., .. i... .. .. .. _ _,... _..x...._....... ._.... .,.-,..........i.................:.......__ ...._..... .... 1. __ _ , ...a t7-... IilOFitkENIION CELL d _...,,._�.. O Gy r VA DCR SWPP 1 PSI d cover enraLnrm li 1. I I i ... .. .......... p_... .., .............I inuF!•u1 Ht!1PC .. .....''.. - :. . j O ✓ ``I .' Performance Based Water qual Calculation Procedure ancn'noni . _......_ - _ _._ . hY .. ......... . _ _. .. .. , ox s:>_„ _ r,x. ,•x ... . . .. ! ....... ...;�ll7ti'. -.-. ...... ...... ..a-c?'.?^�*e-r ....... -.. ....., .. ..., :.. ...., _ ... ....! . .I' .. .. ! I ocalrty has tietar®ilaci land cover txmdthoir! for individual watorshcds widdri its iS.l _ i . I i ;q'!d:!®_ ,) � I, .. i] U J_ 1_. : 9 - erpgce _.orvtwur oiwenssJtaptopttarrrsE;a4aaaa,n•aaalinj -. --._.-- ..---)--�-- m? _.,._ �iaaeir nl(aroiYde :.,: ... ,. -. r•r• a1x >[..=Nd tai. -, trisdictitso rule watershed else value latxanned lot nL as Iwahershad: I l ,. .. .. l ... ... -.. .1.. �.. .%1>r ,_,. by h'- - .. .i.. .. .... _-. , .. .... ) ' Iw�Jer,wt �tP/o ; a. I ..,. cmr«i�..e ,pa,t.s,<�einpmm,na kmlPu.l�laa.l�„Jyai�rol,aavtnrrnml�Jrnm(IXa.�,IP•�y'1, ! : ,. Jim gent � •..' .' - .. .� , 5 eBa,u,ey nffF3Afh (aprcaaal Jodcdalal Pu[m2 14 ic. No. tic. fFrei~La ..'.. _... ., .. .y. .�' i ....... 1.... ..! ....... ..: .. saaemwalYrlw + I i J � i ....... ......F lroliWao[_!mwvil ,.., _.. use Chesapeake 13.ay,dl;faidI value.. .. t .. RtrlP,EguuonX-23 r teal A 22841 No. s. e _.. smanuas t:775Ptthm�,wuddirx[1: la, sx > t•x ..,Othtxwisa, _ - .. t 1,Inr - wlativx tclopnxa wtal(,hoYl,horma aac[ngtpropoavl (pinnde ltMyer) I IxalmGed-1169'i ' .. .... .�� . _. .. .. .. i . f .. .-!. .. r -_� _.... _._�_ .. __'.._.. ._.. ........ .., f t .... _....._. i � C:ONCFNTRATFD WW 05-21-19 �S'QZONAL suanan of SiaeaunZanwnr'fnXnwlLutanon pmoa4rc Nair' i 1 'r' - �eozPoulin ear rear renwsa� FLOW Writs FI�REOAY alMo ¢e_ '. ..,. __..._.1 ....._.. .._. _ _.T. ._�wlmwa_.. ._.. ... 16D6._ -_.. .. .. -..... _. �..._.. ---'i--_ .�- -', .. ... 'L.....ami 3m Pnitnis per gee rampsa. L%q LAX tall - _. ... } } ells YIN jwvw3�ioLq coverI_ �aswPaunea Pa Y, IPLAN MEW .. .._ ._.. .._. _ ....._ L - _-i_. _ Iq _. i .. .. _.. _ _ _ i J _ merasrio ) � I , 1]etenrtoe the eNisl og ts�ervt oia - � - -........._ .. .. _ .! .� � Iitsaa+R•t1=-ZPoundepmYwremoutl i coven of the develop if (ues(at.�-!r ueum• a Oe reYave pman •Pnm p•w•, ma Pr), . .. ... , .. 1 ' ; I d i. - - , .. rr deveb nt un rvmus coven I �---} , .. �i t , ... _. I?aie. _ ...Lx' _ ....�. _ _ , .. .. _ I- - if ._.-:,�1�PoI,IIda PrYaK � : 1 11'e'+!+.e:Xr.=10.05+(O.00Yxra,•„)j><_Ax228 (?M?,aen&t67 .. ' ..,... I. } . ! ! =,rdeare fretdevdorae,swat )ta,epMnna land (pamhper,ym,)'.� .. ,!. _ ! ...... .. ... - ; I , y ...... I . ; �smicaires - arm 0.000 .acre• .... ( I � .... _ .... I j tot - .. of. G[ i Caieulaw the mai IlPtak load 1h s ' ' !.� .. . park'"&- •--.-.._..._ . - ..._ ... .. _ - _s ... ..... _ . �y �•+pL,a ! ,. r I , _ I .... .. .. .. ... ,.. ... .. _.. - ... .. 1 r08dWay. +.- of a � 0.000 'sores .. .,. ) .. - _ ..,L. . L _ -. .. r � - .aT SLQPE F'RO'-FE OR EQUf(L /1 V ]� a PaNNe••NRn6m e,I:a.fPrml a4,u�nfi:=:r•a•aad, _.. i' ... ) ... J. ) .. .� I ! i•�._. 1h,,eeWas - J,unedlea•,11(a_e+.d,�IDLEII�„yrap) ... (EQIAtld13.2� i i "' °09FY61' .. .. -.-_ arm .• Q000 ^,eclat. i f'•J I q ._ r/.�,,��ti E :. I .... .. .. -- _..__ s. __ ... _,.. ' _ .. .. _. .. ... , .. .. _, -.. �}'H err. m ...... .. ... .. _ .. .. i ... ,.... .. wlarc: ' G,.n....•toblpoamaut_loedreuu.ed by praFwYdHMI'sfl��l;��) T 0% z Tea x22_e l ' � . ! � i ; ! �� I i .- 9f M .._.... QODD .... .a0rea _ .l _ ' -. i. ._,.. . - ,. ..� ...__... _ _ .. ..4. __ , _. L _ - ..._ ....... _ I. _.. ...., .-. ..-. I - - _ -_. . ,_. -_ - ! I V fr''[,p `�° Z Ci ICI 'l u It>!�!• .Per .- .-. .. ... . ....... m a6 .I _._..... _ __ ._ ..._ ...... '._ .._.... .. .- _ __ __... �., .i_, ... _l. _.. ,_ ..} ... . .. . ....... _. _ ., _. _ .-.._ _.. L.�.:_..,.,n- leontloedl!nt»Fed BMPIJo. LE oao-2) _ ...- .. 1 _) _. IDoO. .. bS'.�FP�d.._ 9!�.. 1. I. I .... fl- !Total 0 a.f m O.00D.-�,tiCrBB � .. � ., i l.o,....,ea,- PGlldmnluadrinawadla pnNl,rd l?MI'No. 2•Fylnlnw S23 i �-� 1 MAX • (V - _.. ....... . T ; .. .. IY..+_.!4 .... .. .._...... _.. .. ... .,_..... ... _, ..a ... ...... .!.... .. .. .. .. ... l . _ _ ... .... _ ... ... ... ....... I ........... ---....-�- - - - -= --- - - , .•... .. ..... -L. i i-Ln•,.wnaa=....-.OaR load rmwiadbv ^d 13t�Iga 3.Equeam,5-2A.. .. ! i i...._I _ ._._... .per _ .... _..P�•..._...,.... , _.�.... '-.. ... 6 �t �i FULL EXTENDED 'L W fl ".' in ._.._._..._.__.._...._..._.._.....,.-_........................----......__._.......__.._...,.....,._.._____........_,__.._..._...__._...___.:.._.._._.... �pJ.,aN.a�ea.dir=,I.,�n�.wn.).�.... i - s aPi'adw,='asefoCr'+spcea,waw•,a¢baP�•ceMyWv Ary a,IXJlwlnala%W.�I�mel:xNh,X.DmI .I .. , .... .... i ............. _ =(mtalelustiggimparviouscover+A)x100= � .. I .... ,i ... .... � ... ... .. '...... aoa Irmltal.,ae: I.I,aX.d I _. .. I _. ....9. .... _ - ., .. .. .. .. .. . 1 I I �' r _ _. .•.I - -�Tael tip � - DLTCMTIONSTORAGC � fit `�i (oo[ci/, I . ... ( .... _.. .. _... ;.... ..j l.._ ... ! _ .. .... ...._1_ -_ i +iTlte ara8 $hold lie fhE SBrrre 88 I15ed ttl STEP I. _ , _ . .. G. v coaPllamc: Lr..:ri:w> R_ R i I .. ..J-.. ' � I i 'f,�,:.nw,w- 1. ' ! FV Fl t aR � a,._ JCO[YfROLLED i ceX. a » % ran %zze ;_.._ ...-I-•---.. __- -. __.-...__� _ :__. _. __ ____ _. _. .._.., - a+e rx;rr""• -... .. _. � ...... eon _ .. - - - - -01 _ ._._- Pa,mp.ryaenarmta: _. - _,__._.._ .. .. - ... _. t.._ .. ._ � I. _. _ ._. .,_ . ... ..... . :.. .. 1` YR,R 7.86 ToYlrbuvkpvymr-,amvd?._ - --- --- - .._ _.. i . r- -- - - - - - - --- - - - _stun. _ "i� -�]'Relate teri•me y i !P._.__...._t1re�pPrupriatrc.devebpne�taitua.._..... .... _. ..... .... _.� ....... ......... i • _ . L6VEL i? _ LOW OVERFLOW 'I i CQ C � ..... _ .... _. _:.....'..........'..._.... ..... ... ........ .. .... ... ..�8"r?•� _ .. ... ,C .J ,.... .., .. ,.... _..._....... ........ 1. _.. _.. _ ... ..,. , r .., .. ..... ... _. ' : 4 -•'1� :.... _... ... , U � e 1letenafee r aareaa p•d-IbveY rt rIu,YYs.i baA (itd. ,. at e! .P.".•.......__ ._.. _......... ........._,.. ... _� .... ............ _f......... ..... . ... ... ... . .. .... . .. , . , ..} - r- The site ir,fomiatirmtlatermirrA inSTEO 1 and STEP 2 ide iid'W70at1ontotletermlrCthB 'ate _...--.._...........L>rov_... °ro»d?_....___._...-----.._...-_...ePluotri _......... ............ �, ,? •, aF -� � J - O O = ulu+(u 1Nlx rnxz77 .521 I 1E91o°i. - ��?te!.oP!arts;tuationwder_whichtheperfornmacecritKiawiiiapQ)y._Check(-.�theeppropriaadev_eiolMxlentsitvmonasfollows!-. „ ._..., EXTENDED DETENTION W O < W �- i) .. .., ..i .. ,. I . .. ... i .i+)I.. .. 1 i f ' SEGTI9N VIGW� Q ��•'(r�� Jm CC Zi .. wlare. � 'vopoatdvselopacEtaml pinpina[s load (eouodapwpcu)I i - „ ... .: J„ra It,Cat-dmaIcq==mmMp ialaCC6Q(poeomea%Cemdm*1WO [Ib.) I No ;Situation t: .7bis oomists of land da�•elopmem where the c? isl;ng percent imperious cover.(?, ,u�s).is less then or _ a..........._. - • MEASURE SEDIMENT ACCUMULATION LEVELS IN FOREBAY. ._ .,. ; ; _ �egtmltotheavera�l> 1�1aQR1=:TE�"lTI.ON IN SHELF OF EXTENDED DETENTION POND � � r p A - IJpp11CLIrIC aRY (aWCE) -- >. - , ... i ,cover condition,lwatarsted)a�dthl:praposedlmprev_emeras,wdlcreareaaomlperce!u. • MONITOR THE GROWTH OF WETLANDS TREES AND SHRUBS PLANTED. l - t'� I Laid ❑ � __ I_ .! - �.. ..._. _ __- -_.-� -} ._. ...___...,"____..I _._ -- ! Lra,=(o.os+io.009x zsx `pJ x 7ps xz31 � _ ( . __ ..!mperviotscoyer.(tpnst)whichisl�sdymoregiml.tothe coverpondegonfiwatarshed). .... PEC AND THEIR APPROXIMATE COVERAGE,AN'DNOTE Nalsc [Post 5d% 5 16% THE PRESENCE OF ANY INVASIVE � Q m J 0.� . _ ; i ; .� wvia Pp ) _ _ . - __ ._ - OF STORMW ATERINLETST O THE POND FOR ItXimWlreredlBeXsa.:8re8rll Q .rp•(. _ } .. } I _ ..• --•-t'lln9G016rSLtOfta[ddevel ...... _. . _ • INSPECT THE CONDITION z ... ... .. _I. .� ... .. .. .._ .I _ ;.. ,. .. ., - .. aces uBtaml.a�eR�r,r..,ml,[Xs..,_..a•R��...---...._.....__...._...__..__.---,._-----._.__.........,_..__.__......_...._....__..,-.__.....:.._� , Y•9 •,WHOa2: f i ]One COVET lgilb )ISM-esL�r=1, .. ERIALDAMA E ER I RUNDERCUTTING . __...._,....; ,_ consists _....,._.. ...._ 4 MAT OS ONO : t .. __.._._.........._................._...._._,._...�........._...,...-•---_....._.��.,__....'"�*"__......_.......(...__�_..,__.....,__.._�..._.. G> die r f Fiure9.6.T TealDetailofaBioretentionl3asinwith-ntheU erShelfoanEGlPond 9 YP PP � � . i RR= rro.--(o.HxtP,N,•.gp i d.co ev comiitiwwher tend dc,proposad improvcmcma will tt t1,mi accu . • INSPECT THE BANKS OF UPSTREAM ANDNDE DOWNSTREAM CHANNELS FOR 10-�.. care a e min aR = sa , ,-,; (- as ( .,__.._ ......._�._,.. .,. - .- ,. _ _.... - _ ,imperviola.coign(Lpost)whic_h_is�terthanlhcaym land cgve{cagdifim.(iwatersied): -. I .. EVIDENCE OF SLOUGHING, ANIMAL BURROWS, BOGGY AREAS, WOODY �Tnte ��y�� r6% I ' 0 p., i tree=: a.zr )X,ud.*ps!+crer _.. .. _.e _._ , . _ .. .� - -.... I . _..-_ _! _ _ } • -- I i - �a���, ._.... _. _ ...__..... GROWTH, OR GULLY EROSION THAT MAY UNDERMINE QvIBANKMENT ..._ ___... _ _ - >. - - - ANNUAL BMP as ( I J I and I I � IIVTEGRITY. � iw ! i i' I ( True. r.. _�,.. �> h'^• 16% I r .. _ �....... _. • INSPECT POND OUTFALL CHANNEL FOR EROSION, UNDERCUTTING, �..:_ LLI RR - s. L1�r :. ?.? - ... rap', ,.� paodsPo[}c•r i � ' J '. .. I =.. _.. _ ., »_.. --., RIP RAP DISPLACE WOODY GROWTH, ETC - �_ _ ... .-_..'_._.,. - ---. __... _ _, .., ...L_ . _ _ I _ ........_-.L- - DISPLACEMENT, H, ! BIORETENTION 06 . .... _. i........ .j..... ..... .. ....... ;....� ..-.....'...... .......1.._..... ...........i t.w it.I No iSitnafioa3:'This cmisishufland rloveloprnelawherathnexisti, percmtirripervieuscwm(ba•ene)isgaetCriban ! • INSPECT CONDITION OF PRINCIPAL SPILLWAY AND RISER FOR ! Paarr rei.) i .&teo7- 'tdemiyheatmwaaelmeatp[aline (BNPJ Tor tee sae. , 1 } toyer cGn iition Iwatcrsl cd), ., .. I ..... j ._ EVIDENCE OF SPALLING, JOINT FAILURE, LEAKAGE, CORROSION, ETC. � � tg% • INSPECT CONDITION OF ALL TRASH RACKS REVERSE SLOPED PIPES OR Fa6e lAarhp 1wi,eerlyd i• j( • MOWING OF GRASS FILTER STRIPS AND BIORETENTION TURF COVER AT LEAST 4 TIMES A YEAR • SPOT WEEDING, EROSION REP TRASH REMOVAL, AND MULCH RAKING TWICE DURING GROWING SEASON u -_ ,ka,udvtlx_ ,bmremaial _.:.'.. 6rllx ak., RT@wI I J .. _ _ I . ........ i - i FLASHBOARD RISERS FOR EVIDENCE OF CLOGGING, LEAKAGE, DEBRIS i . Sitaatina a: tThis consists of land dcvroloprixr t wlwre iF c cdst ng pence t imp xvima cover (Im#,ns) is served by an I ACCUMULATION ETC. ' ' "-- - - - -t • ADD REINFORCEMENT PLANTING TO MAINTAIN DESIRED THE VEGETATION DENSITY AS NEEDED • REMOVE INVASIVE PLANTS USING RECOMMENDED CONTROL METHODS AS NEEDED FILE NUMBER EAT - ( NR +_{..:,.) x less (Eql elmns•zn . ,....-. j . ,--,.; . J.. .. .... ..:... .. ..... ! • INSPECT MAINTENANCE ACCESS TO ENSURE IT IS FREE OF WOODY -exlStal�T alOrmiVaier IIIDOB((eEleOt BMI�a) d7dt fldf1CC WaIQ�I Bali'... ... 1 ...._. . • STABILIZE THE CONTRIBUTING DRAINAGE AREA TO PREVENT EROSION AS NEEDED _;I -: ,_ F . ........... .... _ _. _� .._ . - .�,_ _ •- - .__ ._----...__.., _.. . _.. __:........ .... _ ._ -- __ .. _ VEGETATION, AND CHECK TO SEE WHETHER VALVES, MANHOLES AND • SPRING INSPECTION AND CLEANUP 8053 I - Luc = irattuaeun cav,t my mo xm (pounds pxrytaq ! _' --_.-- r ` LOCKS CAN BE OPENED AND OPERATED. If rile promised developn�ritnee(s the criteria for devel iee Situauon,I,... . '; , t I • SUPPLEMENT MULCH TO MAINTAIN A 3 INCH LAYER _ 1.Ga(.Indx,zla.•erxlblv.:da a}aad,hw•um,s2lpoad%J� ..1. !.., i... ._ ;ganthelowdeeit dayel scorls,deredtobe.lheHMPmidtro Ilutamreno.alis lare;l., ( 1. • INSPECT INTERNAL AND EXTERNAL SIDE SLOPES OF THE POND FOR - Jn • PRUNE AND N PRE-TREATMENT SEDIMENT SHEET ! ' tbecritertaf EVIDENCE OF SPARSE VEGETATIVE COVER, EROSION, OR SLUMPING, �-calcnlah[m -adore fvr $rtuation) stops tine,-Ifthe proptugx) d lopmertmee•ts , ', devel<!palmd 'Tip pr[x IES • REMOVE CELLS AND INFLOW POINTSONCE EVERY 2 TO 3 YEARS Sitlm(ian 2, 3, or 4, thcmpnn and to STEP 4 on tho mwopriate workvlmcx. I ( i AND MAKE NEEDED REPAIRS IMMEDIATELY. • REPLACE THE MULCH LAYER EVERY 3 YEARS � C1.1 L ►.1_ POST BMP CONVERSION STAGE -STORAGE Elev(Ft) Storage(CF) Storage(CY) Storage(Acre-Ft) Area(SF) Area(Acre) 642.000 0.000 0.000 0.000 195.840 0.004 644 000 831 004 30.778 0.019 661.054 0.015 646.000 2823.802 104.585 0.065 1361.270 0.031 648.000 6453.083 239.003 0.148 2296.149 0.053 650.000 12157.308 450.271 0.279 3436.624 0-079670 652.000 20376.829 754.697 0.468 4818.813 0.111 654.000 31584.229 1169.786 0.725 6426.504 0.148 656.000 46234.511 1712.389 1.061 8261.695 0.190 BASIN STORAGE PROVIDED = 1441 CY @ 655.00 (TOP OF DAM) 665 STORM EVENTS FOR BIORETENTION FACILTY EVENT INFLOW (CFS) ROUTED (CFS) 2-YR 10.95 6.60 10-YR 20.62 8.87 660 100-YR 39.86 40.63 STORM EVENTS FOR EXTENDED DETENTION FACILITY EVENT INFLOW (CFS) ROUTED (CFS) ELEVATION (FT) STORAGE (CF) 2-YR 14.02 8.83 650.25 13,172 655 10-YR 26.08 19.49 651.27 17.380 100-YR 89.43 90.60 652.32 22,180 DAM CONSTRUCTION NOTES: 1. GEOTECHNICAL CONSULTANT TO SPECIFY DAM EMBANKMENT MATERIAL, SEEPAGE CONTROL DEVICES, CUT-OFF TRENCH DESIGN, CULVERT BEDDING REQUIREMENTS, AND OTHER APPROPRIATE GEOTECHNICAL 650 DESIGN REQUIREMENTS. 2. IMPERVIOUS CORE SHALL EXTEND TO THE 10-YR WATER SURFACE ELEVATION UNLESS OTHERWISE NOTED. 3. FOUNDATION AND ABUTMENT AREA EXTENDING 10' BEYOND DAM FOOTPRINT SHALL BE CLEARED, GRUBBED AND STRIPPED OF ALL VEGETATION TOPSOIL AND/OR ORGANIC SOIL AND OTHER UNSUITABLE MATERIALS. 4. AFTER CLEARING, GRUBBING, STRIPPING, AND REMOVING ANY OTHER UNSUITABLE MATERIALS, THE SUBGRADE SHALL BE PROOF -ROLLED WITH COMPACTION EQUIPMENT UNDER THE OBSERVATION OF A 645 QUALIFIED ENGINEER. THE COMPACTION EQUIPMENT SHALL CONSIST OF THE HEAVIEST POSSIBLE EQUIPMENT THAT WILL NOT CAUSE DISTURBANCE OF SUITABLE SUBGRADE SOILS. EXCESSIVELY SOFT OR UNSUITABLE MATERIALS SHALL BE REMOVED AND REPLACED WITH COMPACTED FILL. WHERE ROCK IS EXPOSED AFTER STRIPPING OR UNDERCUTTING, ALL LOOSE ROCK MATERIAL SHALL BE REMOVED PRIOR TO PLACING COMPACTED FILL. ROCK SUBGRADES SHALL BE INSPECTED AND APPROVED BY INSPECTOR OR ENGINEER PRIOR TO PLACEMENT OF FILL. 5. COMPACTED FILL SHALL NOT BE PLACED PRIOR TO PERFORMING THE REQUIRED FOUNDATION AND 640 ABUTMENT PREPARATION, OR ON ANY FROZEN SURFACE. COMPACTED FILL SHALL EXTEND TO THE FILL LIMIT LINES AND GRADES INDICATED ON THE APPROVED CONSTRUCTION PLAN. COMPACTED FILL MATERIAL SHALL BE OF THE TYPE CLASSIFICATION SYMBOL SPECIFIED BY THE GEOTECHNICAL CONSULTANT, OR OF A BETTER QUALITY MATERIAL AS DEFINED BY THE UNIFIED SOIL CLASSIFICATION SYSTEM (USCS). RESTRICTIONS ON LIQUID LIMIT AND PLASTICITY INDEX OF MATERIAL MAY BE INCLUDED WHERE APPLICABLE. COMPACTED FILL SHALL CONSIST OF MATERIAL FREE OF ORGANIC MATTER, RUBBISH, FROZEN SOIL, SNOW, ICE, AND PARTICLES WITH SIZES LARGER THAN 3" OR ANY OTHER DELETERIOUS MATERIAL. 635 6. COMPACTED FILL SHALL BE PLACED IN HORIZONTAL LAYER of 10"-12" IN LOOSE THICKNESS. ACTUAL LIFT THICKNESS SHALL BE SPECIFIED BY THE GEOTECHNICAL CONSULTANT. THE MOISTURE CONTENT SHALL BE CONTROLLED SUCH THAT COMPACTION IS ACHIEVED WITHOUT YEILDING OF THE SURFACE. EACH LAYER SHALL BE UNIFORMLY COMPACTED WITH SUITABLE COMPACTION EQUIPMENT TO AT LEAST 95% OF STANDARD PROCTOR MAXIMUM DENSITY IN ACCORDANCE WITH ASTM D-698, AASHTO T-99, OR VDOT SPECIFICATIONS. ANY LAYER OF FINE GRAINED FILL WHICH BECOMES SMOOTH SHALL BE SACRIFICED TO A DEPTH OF 2" TO ALLOW ADEQUATE BONDING BETWEEN LAYERS. 7. COMPACTED FILL WITH A MOISTURE CONTENT WHICH WILL NOT PERMIT COMPACTION TO THE SPECIFIES 630 DENSITY STANDARD SHALL BE SACRIFICED, DRIED, OR WETTED AS NECESSARY TO PERMIT PROPER COMPACTION. to GENERAL BIORETENTION NOTES: ccn co 1. ALL DRAINAGE AREAS TO A BIORETENTION FACILITY ARE TO BE STABILIZED PRIOR TO INSTALLATION OF AMENDED SOILS, MULCH OR PLANTINGS. 10 2. AMENDED SOIL WILL ONLY BE PERMITTED WITH A VALID SOIL ANALYSIS REPORT. NO AMENDED SOIL SHALL BE ALLOWED ON THE SIDE SLOPES. 3. UNDERDRAIN PIPE SHOULD BE MIN. 6" PERFORATED SCHEDULE 40 PVC (PER AASHTO M278) OR DOUBLE WALL HDPE (PER AASHTO M252). PERFORATIONS SHOULD BE 3/8" SPACED 6" ON CENTER ALONG 4 LONGITUDINAL ROWS SPACED 90' APART. 4. UNDERDRAIN CLEANOUTS SHOULD EXTEND A MIN. OF 6" ABOVE MAXIMUM PONDING ELEVATION. ONE CLEANOUT MAY BE FLUSH WITH TOP OF SURFACE TO ALLOW DRAWDOWN. 5. ONLY SMALL MATURING TREES ARE ALLOWED TO BE PLANTED IN THE AMENDED SOILS. 6. A PERMANENT MAINTENANCE ACCESS EASEMENT MUST BE PROVIDED AROUND THE PERIMETER OF ALL @MPS TO ALLOW FOR ADEQUATE MAINTENANCE AND REPAIR. 7. AMENDED SOIL WILL ONLY BE PERMITTED WITH A VALID SOIL ANALYSIS REPORT. 8. INSTALL WIRE SCREENING AS NECESSARY AROUND ALL OUTLET OPENINGS TO PREVENT LOSS OF MULCH. BIORETENTION WITH EXTENDED DETENTION NOTE: THIS SHEET IS FOR INFORMATIONAL PURPOSES FROM APPROVED PLAN DATED 5-21-2019 ------ - -- -- ------ -- ----- - ----------....---_.---- .._ ___ -' -- ---'----------- -'---- - _ __...---'- --- _. BY ROUDABUSH GALE & ASSOC. INC. - PROPOSEI I GRADE EX GRADE 24 HPD P E -__ OUTLET ROTECTIO ---- - --- _� _- - ---" - --_- _ _ -'-- --' --------- TOP OF BIOFILTER MEDIA EL: 655.' 3" SHREDDED HARDWOOD MULCH LA R - STONE WIER & SLOPE PROTECTION - - - - - --- - CiA S 5 '' PRETREATMENT CELL 16'x243' RIPRAP _ EX TOP OF DAM 655.00 --- ---- - _ - _ ---- - --+ 1 } - ---...._---'-- '-------•..-.-....._-._._._ --'- .. - -_---- __. .._ - --- ---- --- -- EL: 656-- - --- _ - - -� ----- --'--- - _ - _ ._ _'.__-_ EX. 25' EMERGENCY -7) SPILLWAY=653A0 _ ..__-__-•--_-----_-- � EXISTING----".-___. 60 " RCP RISER 6" MAX PONDING . , �,� -c-�s-p C-c -v,- -,i a- -R^- x d �`.* { 'Y' ���ggq�1'< .t ,. � rL � , � � Y. ,�,>` ti�'"'"`• r� ok'�%"'''k� i __-__..___._--•__ •_-.._._. ._ -.. __ - - a• u• '1 .�� X.S �J�('�'bq _ __ _ _ X, �k � q�^�I X,Y EXISTING x. .,:r, � _ _- a-x� ^4-��z-g^ a 7 > -�-.w ' � 'v Y v.�'♦XJR y " {'� ,[ .C' S� .. ,q�, t N!•' F � .X' � Y_'�+•�-Ah= C � > ' A � is<'� ,",�: xu. '�r�*.�'"��i,. ���. ,. t t` t"" -- --_---._-----_.-_ „ .'k'SXi-�`" 4-DEWATERING �.,[, . rr ' ?'i�7r"n," FA1�ay"�"„ � 0-RIFICE 64950 t ,. .a� ,.' �''4, ,. '�". r A. �i�'��`.�, y � ,,N � x��r1� 4 ;y x'} ✓ ;x x� h?l +�� - F xY •< K�>f i1'' X� �^. .., K� r ___-_----------- - ------------------------- _ __ __-.---�...--___-- --. _ __. _____ .........___... _---'___-- - - STONE DIAPHRAGMS w/ 48" OF CLEAN WASHED _._._..__--_-_-•---------_-.__. ? _.._._.___._.____,____- - - __.___._...--._. ._.. _.-_-_ __ ____.-_--_.__.._______ _ _._. _-._-- _ ____.-------.__-_- .-_- .-_.__..--_______--- #57 GRAVEL TO INCLUDE UNDERLYING FILTER FABRIC. --- ___ .---_-__--------_.-_-- r- BOTTOM EL: 653 -----'-----_-- -. 36" BIORETENTION SOIL MEDIA _ ------------------------1_.____.__..--------------.- ..__..__ BOTTOM EL: 652.5 MIN PEA LAYER - TOP EL 656 __.'3 EL 652.45E ____ _._ ..._-__ .-.__._ SC OR 12 MIN #57 GRAVEL SUMP LAYER EQUIVALENT CORRUGATED HOPE SLOPE TO INCLUDE UNDERLYING FILTER _ .5 .. _- _._. FABRIC BETWEEN PVC AND CHOKER STONE .S s • . '. r f EX BOTTOM OF EXTENDED DETENTION FACILITY = 642.00 (2) NEW B"ORIFI=642.25 REFER TO SHEETS C2.0 & C2.1 FOR ----- - - -------__.-.-._.-.--_---------.__�_____-__-------------__.__ _.---'---_------__---_� - _. __.... EXISTING EXTENDED DETENTION __.-__..------..-___ _ ---_------__- ___�_______. AMENDED CHANNEL AND BIOFILTER - ------- _.__.. -----_-------__--- -.._..__--__ _.___. FACILITY AND OUTFALL TO REMAIN. - - - ---- -- ---_- -- ' --- ---- ---- _ -__-- ' DESIGN. _ --- - - EX OUTLET PROTECTION EX 105' OF 36" RCP BARREL - -- ---- '-- - --- -� -- __ INV IN=642.00--- - --- -- --- -- - -- - - __ _.. - ------ --- - ____._----------__._-.--.-_-- -•___-_ INV OUT=640.25 SLOPE=1.67% ____._.___.__.-_ _._-- --- _ _- --- - _ ._-_. --.- ----- -------.._". - -- ----__.-. __..,. __� -_------------- ---- ---_ -- ----------- -- .. cO r. R oLO on 0M CD 00o 0) LOa CD cy� C0 of n coo r too tow mm cactoo mi� m� 06 ctOoCO cc; +00 11+00 12+00 13+00 14+00 UnD17AKITAl rnAI C. 1" On' \TDTn AI C!`AI C• 1" • F' MAXIMUM Q2YR FLOW. REFER TO SHEET C2.1 FOR AMENDED QUANTITY CALCULATION SUMMARY. b. Adequacy of all channels and pipes shall be verif' in the PROPOSED V/W SWM following manner: EAS ME 23'51"e BIOFILTER: 6,465 SF E NT \\ (2) (a) Natural channels shall be analyzed the use of a 216.2T 2 PROVIDED AT ELEVATION two-year storm to verify that stormwater ill not overtop channel PRETREATMENT CELL: _'- 656. FILTER MEDIA 36".{' banks nor cause erosion of channel b or banks. 16'x24'x3' STONE STORAGE TANK BIOFILTER S63'2T24 57 Q2YR PRE -DEVELOPMENT = 9.2B CFS UNDERDRAIN. CLEANOUTS - BIOFILTER ;, �,, i i ,-\. X),d�` 20' ON CENTER •��r■ OUTFALL w, . Q2YR Pos-r-DEVELOPMENT - 8.83 CFS �^rw ..+y �. • ! -4.10 Q2YR POST -DEVELOPMENT = 8.83 CFS 5 Q2YR PRE -DEVELOPMENT = 9.28 CFS '�,, `' �� -'M1 n f \. \. �• ) �. 9VAC25-870-98 FLOODING. A. Downstream properties and waterways shall be protected from damages from localized flooding due to changes in runoff rate of flow and hydrologic characteristics, including, but not limited to, changes in volume, velocity, frequency, duration, and peak flow rate of stormwater runoff in accordance with the minimum design standards set out in this section. B. The 10-year postdeveloped peak rate of site shall not exceed the 10-year predeveloped peak rate of runoff. QI DYR PRE -DEVELOPMENT = 27.38 CFS MAXIMUM Q10yR FLOW, REFER TO Q10YR POST -DEVELOPMENT = 19.49 CFS 5 Q1OYR PRE -DEVELOPMENT = 27.36 CFS SHEET C2.1 FOR AMENDED QUANTITY CALCULATION SUMMARY. STREAM CHANNEL EROSION 8c FLOODING ANALYSIS A portion of the exisitng creek that will receive site runoff was visually inspected by Roudabush, Gale & Assoc. in order to obtain design information to evaluate existing conditions, as well as post -development conditions. The following observations/evaluations were made: 1. The creek appeared to be a rectangular channel with moderate to steep side slope banks. The banks varied in height but showed consistency of 2 feet or more. Water was present in the channel with a gentle flowing depth of 3-3.5 inches. The width of the creek channel varied between 4-5 feet. The creek appeared in good health and lined with natural earthen cover with some tall grass and weeds present. Soils appeared to be clay loam with natural erosion. 2. Calculations were run using the pre -development and post development conditions for the two and ten year storm events and were evaluated as such. 3. The bmp measures put forth for the proposed development provide a reduction in the runoff velocity exiting the site for both the two and ten year storm events. Projected values for the flow depth in the channel were obtained by forecasted linear trend methods and appear to show no threat of overtopping the banks of the existing channel. By reducing the velocity exiting the site, the measures will be providing additional relief of natural erosion of the exisiting channel banks, thus satisfying 9VAC25-870-97. 4. While the volume of flow will increase naturallty due to the project development, the rounoff from the site will be routed through multiple, complex design measures that will react to the increased volume and account for the peak intensity the hydrograph produces from the two and ten year storm events. No localized flooding is visually present at this time in the existing channel. The bmp measures will decrease the rate of flow that is exiting the site, reduce the velocity, and spread the peak intensity over a longer duration during a storm event, thus decreasing localized flooding satisfying 9VAC25-870-98. �� " � :..f%� ...Y y ,,... ....Y r +: p% y^'r 1,,r y. . r «.,., d y, ,, '., -.., •, ,".'�, ;";.., .I ... _...,+ r a .. .�..y y r r '« a y « r y • f' rr'i ~,a y • y d '' ,�� },'� :".w." � � r �� �_. A >'f Il"" � � .r. , a a i, a Y y_. .,. y... ri'• y '. r r � �, . y .: 'r.'a x y x a � � .�! ,_ /'/, .' .., ;. .., d y � y \« r dry f• F r «/ •, r a a � �.. \, ,p ..y.. r ..%'. « ',. a G �a''J ^' « ! !+ S 'r a u - s-. i!"..�..3 .,�., e ...a .. \ 1 - f•/ r .� , ,-�, -��. '" � . ' y � � " Y d " i1 x a d • � `� i• ��__ }'''' t.'j x MM(30 .. ---- r 1: • PROPOSED CLEANOUTS J PRE-TREATMENT CELL •� xr , � x ,, ''; STONE DIAcap i • "'';,> .r,+ 1� I '� �F r`,,\, , \ PHRAGM, , CLASS 1 RIPRAP 1 i� VEGETATIVE BUFFER ZONE FOR EXTENDED DETENTION BIORETENTION AND EXTENDED DETENTION PLAN VIEW y } ri 40' 30 0 30 60 90 SCALE: 1"=30' w151) z� r' Z � o >r @) V O a °' , o yy�� vJ Q w LU Z J Jou C _ ex rq¢ W a -J2 i0 x O oa Im" 2 (6 ON y� ❑v Wq 4.2 O� ¢X W j CtIt Ou to 4W Mt fawo 1�+ Z ' n ©� w w z CA ,- 2 mZ w Z w a- O�II % REVISIONS COUNTY COMMENTS Feb 15, 2019 COUNTY COMMENTS April 15, 2019 FOR APPROVAL May 21, 2019 CONTOURS 2 FOOT DATE October 22, 2018 SCALE AS SHOWN ,AyTH aF D o c i JiMIT gart .o C. No. a 05-21-19 w� �Ss10NAL ili rs 0 O o w Z0 O w 0 LLI wad a Zks 4;k --a CZZJ`r) an/ i Z wpp<(OW F w co ���mg ©_J m a 0Z0 (n U U) 0 U.1 06 FILE NUMBER 8053 SHEET C1.2 L BMP: SWM A Grass Channel Proposed Condition forTR-55 HSG RCN Area(ac) % RCNxArea I (Impervious) 98 2.52 70% 246.96 B (Managed Turf) 61 1.09 30% 66.49 B (Forest) 55 0.00 0% 0 TOTALS 3.61 87 RCN = 87 Site Rv (Rv Coefficients x Land Cover %) Managed Turf B Soils, Rv = 0.06 Forest B Soils, Rv = 0.00 Impervious, Rv = 0.66 Rv = 0.72 Other Design Requirements Meets Requirement? Comments Yes Channel sideslopes 3HAVor flatter Yes 3H:1V Maximum drainage area <5 acres Yes 3.61 Longtitudinal slope<4% Yes 4.00% 10-yea r storm conta i tied withi n cha nnel Yes 0.3 feet freeboard for 10-year storm I Yes 10.43 feet provided A AAA y���j;�. • • r Table 3.3: Maximum Permissible Velocities for Grass Channels Erosion Easily Eroded Cover Type Slope (%) Resistant Soils Soils (ft./sec.) ft./sec. Bermudagrass 0-5 6 4.5 Kentucky bluegrass Reed Canarygrass 0-5 5 3.8 Tall fescue Bermudagrass 5-10 5 3.8 Kentucky bluegrass Reed Canarygrass 5-10 4 3 Tall fescue Grass -legume mixture 0-5 4 3 5-10 3 2.3 Kentucky bluegrass Reed Canarygrass > 10 3 2.3 Tall fescue Red fescue 0-5 2.5 1.9 DRAINAGE AREA = 3.61 AC CN= 87 TC= 14.5 MIN. n=0.20 (SHORT GRASS) Q(1) = 5.41 CFS Q(2) = 7.03 CFS Q(10) = 12.27 CFS MAX. FLOW VELOCITY (1YR.) = 0.97 FT/S MAX. FLOW DEPTH (1YR.) = 0.69' MAX. FLOW VELOCITY (2YR.) = 1.05 FT/S MAX. FLOW DEPTH (2YR.) = 0.80' MAX. FLOW VELOCITY ('I OYR.) = 1.25 FT/S MAX. FLOW DEPTH (1 OYR.) = 1.07' DESIGN DEPTH =1.50' LENGTH = 110' WIDTH = 6' MIN. SLOPE = 4.0% Sources: Virginia E&S Control Handbook, 1992; Ree, 1949; Temple at at, 1967; NOVA, 2007 Table 3.5. Suggested Spring Maintenance Inspections/Cleanups for Grass Channels Activity Add reinforcement planting to maintain 90%turf cover. Reseed any salt -killed vegetation. Remove any accumulated sand or sediment deposits behind check dams. Inspect upstream and downstream of check dams for evidence of undercutting or erosion, and remove and trash or blockages at weep holes. Examine channel bottom for evidence of erosion, braiding, excessive ponding or dead grass. Check inflow points for clogging and remove any sediment. Inspect side slopes and grass filter strips for evidence of any rill or gully erosion and repair - Look for any bare soil or sediment sources in the contributing drainage area and stabilize immediately. Channel Report Hydra flm Express Extension to AuWEeek®AUNCADa Civil 3131l by Autodesk, Inc. GRASS CHANNEL (2-1 Trapezoidal Bottom Width (ft) = 6.00 Side Slopes (z:1) = 3.00, 3.00 Total Depth (ft) = 1.50 Invert Elev (ft) = 659.00 Slope (%) = 4.00 N-Value = 0.200 Calculations Compute by: Known Q Known Q (cfs) = 7.03 Elev (ft) 661.00 660.50 660.00 659.50 659.00 Section Friday, Apr 12022 Highlighted Depth (ft) = 0.80 Q lots) = 7.030 Area (sgft) = 6.72 Velocity (ft/s) = 1.05 Wetted Perim (ft) = 11.06 Crit Depth, Yc (ft) = 0.33 Top Width (ft) = 10.80 EGL (ft) = 0.82 Channel Report Hydrai Express Extension for Anodesi Masi CMI 3M by Aulodesk, Inc. GRASS CHANNEL (10-YR) Trapezoidal Bottom Width (ft) = 6.00 Side Slopes (z:1) = 3.00, 3.00 Total Depth (ft) = 1.50 Invert Elev (ft) = 659.00 Slope (%) = 4.00 N-Value = 0.200 Calculations Compute by: Known Q Known Q (cfs) = 12.27 Depth (ft) Elev (ft) 2.00 661.00 1.50 660.50 1.00 660.00 0.50 659.50 0.00 659.00 658.50 -0.50 0 2 4 6 8 10 12 14 16 18 20 Reach (ft) Section BMP: SWM B Biofilter - LEVEL 2 Runoff Coefficients (Rv) A Soils B Soils C Soils D Soils Forest/Open Space 0.02 0.03 0.04 0.05 Managed Turf 0.15 0.20 0.22 0.25 Impervious Cover 0.95 0.95 0.95 0.95 Proposed Condition for TR-55 HSG RCN Area(ac) % RCNxArea 1 (Impervious) 98 2.52 70% 246.96 B (Managed Turf) 61 1.09 30% 66.49 B (Forest) 55 0.00 0% 0 TOTALS 3.61 87 RCN = 87 Site Rv (Rv Coefficients x Land Cover %) Managed Turf BSoils,Rv= 0.06 Forest B Soi Is, Rv = 0.00 Impervious, Rv 0.66 Rv = 0.72 Treatment Volume, Tv (Spec. No. 9, Table 9.4) Tv = [1(1.25 in) x (Rv) x (A)) _ 121 - volume reduced by upstream BMP DrainageArea,A= 157,252 sf Upstream Vol ume Treated = 7,585 cu ft *per RRM 3.0 Column E Treatment Volume, Tv = 4,267 cu ft Required Treatment Volume - Storage Depth Storage Depth (ft) Void Ratios Ponding Depth= 0.50 1.00 Depth of Media Filter= 3.50 0.25 Stone Sump Depths: 1.25 0.40 Treatment Volume, TV = 1.88 ft Provided Treatment Volume - Surface Area Minimum Required Surface Area= 2,275.71 sf Surface Area Provided= 2,280.00 sf Forebay Volume Required Forebay Volume= 640 cf Volume Provided= 645 cf WATER TABLE NOTE: THE LOCATION OF THE GRASS CHANNEL AND BIOFILTER DESIGN CONTAINS SOIL CLASSIFICATION 4E ASHE LOAM AND HAS A MINIMUM DEPTH TO THE WATER TABLE OF MORE THAN 80" OR 6.67' BELOW GRADE. THE MOST RESTRICTIVE DESIGN FOR THE SWM FACILITIES WOULD BE THE EXCAVATED MATERIAL TO THE BIOFILER BOTTOM. THIS DESIGN PROVIDES MORE THAN THE RECOMMENDED 2' OF SEPARATION BETWEEN THE MEDIA BED AND WATER TABLE AND POSSES NO FORESEEABLE CONCERN WITH GROUNDWATER CONTAMINATION WITHIN THE FILTER MEDIA. Frker, Apr 1=2 Highlighted Depth (ft) = 1.07 Q tots) = 12.27 Area (sqft) = 9.85 Velocity (ft/s) = 1.25 Wetted Perim (ft) = 12.77 Crit Depth, Yc (ft) = 0.47 Top Width (ft) = 12.42 EGL (ft) = 1.09 Depth (ft) 2.00 1.50 1.00 0.50 0.00 658.50 -0.50 0 2 4 6 8 10 12 14 16 18 20 Reach (ft) 6"CLEANOUT 3" HARDWOOD BARK MULCH BOTTOM ELEV 654.75 42" BIOFILTER MIX BOTTOM ELEV 65125 3" NO. 8 STONE TOP ELEV 651.00 15" NO. 57 STONE ELEV. 649.75 PVC UNDERDRAIN FABRIC OR EQUIVALENT. TO BE 2' WIDE CENTERED ON UNDERDRAIN NOTES 1. 42" BIOFILTER MEDIA DEPTH SHALL BE THE MINIMUM DEPTH AFTER A SETTLING PERIOD OF THREE DAYS. 2. FILTER MEDIA MUST BE SUPPLIED BY AN APPROVED VENDOR SWM-B - LEVEL 2 BIORETENTION ALONG UNDERDRAIN Kin Cral F VA DCR STORMWATER DESIGN SPECIFICATION NO. 9 Table 9.7. Bioretention Material Specifications BIORETENTION Material Specification Notes Filter Media Filter Media to contain: • 80% - 90% sand The volume of filter media based on 110% Composition • 10%-20% soil fines of the plan volume, to account for settling • 3%-5% organic matter or compaction. Available P between L+ and M per Filter Media Di 2005 Nutrient Management The media should be certified by the Testing Criteria. supplier. Mulch Layer Use aged, shredded hardwood bark Lay a 2 to 3 inch layer on the surface of the mulch or stable coarse compost. filter bed. Alternative Use river stone or pea gravel, coir and Lay a 2 to 3 inch layer of to suppress weed Surface Cover jute matting, or turf cover. growth. Loamy sand or sandy loam texture, Top Soil with less than 5% clay content, pH 3 inch surface depth. For Turf Cover corrected to between 6 and 7, and an organic matter content of at least 2%. Use anon -woven geotextile fabric with Apply only to the sides and directly above Geotextile/Liner a flow rate of > 110 gal./min./sq. ft. the underdrain. For hotspots and certain (e.g., Geotex 351 or equivalent) karst sites only, use an appropriate liner on bottom. Choking Layer Lay a 2 to 4 inch layer of sand over a 2 inch layer of choker stone (typically #8 or #89 washed gravel), which is laid over the underdrain stone. Stone Jacket for Underdrain 1 inch stone should be double -washed 12 inches for the underdrain; and/or Storage and clean and free of all fines (e.g., 12 to 18 inches for the stone storage layer, Layer VDOT #57 stone). if needed Use 6 inch rigid schedule 40 PVC pipe Lay the perforated pipe under the length of Underdrains, (or equivalent corrugated HDPE for the bioretention cell, and install non- Cleanouts, and micro-bioretention), with 3/8-inch perforated pipe as needed to connect with Observation perforations at 6 inches on center; the storm drain system. Install T's and Y's Wells position each underdrain on a 1% or as needed, depending on the underdrain 2% slope located nor more than 20 feet configuration. Extend cleanout pipes to the from the next pipe. surface with vented caps at the Ts and Ys. Plant one tree per 250 square feet (15 Establish plant materials as specified in the feet on -center, minimum 1 inch landscaping plan and the recommended caliper). plant list. Shrubs a minimum of 30 inches high In general, plant spacing must be sufficient planted a minimum of 10 feet on- to ensure the plant material achieves 80% Plant Materials center. cover in the proposed planting areas within Plant ground cover plugs at 12 to 18 a 3-year period. If seed mixes are used, they should be from inches on -center; Plant container- a qualified supplier, should be appropriate grown plants at 18 to 24 inches on- for stormwater basin applications, and center, depending on the initial plant should consist of native species (unless the size and how large it will grow. seeding is to establish maintained turf).- 0 General Filter Media Physical Composition. The mineral soil texture of the bioretention soil mix should be loamy coarse sand with no more than 10% clay, no more than 20% silt + clay and at least 75% of the sand fraction should be coarse or very coarse sand. • To allow for appropriate Cation Exchange Capacity (CEC) and nutrient removal, the fnix should contain at least 10% soil fines (silt + clay) while meeting the overall texture specification above. The particle size analysis must be conducted on the mineral fraction only or following appropriate treatments to remove organic matter before particle size analysis. The Filter Media should contain 3% to 5% organic matter by conventional Walkley-Black soil organic matter determination method or similar analysis. Soil organic matter is expressed on a dry weight basis and does not include coarse particulate (visible) components Table 9-8. Suaaested Annual Maintenance Activities for Bioretention Maintenance Tasks Frequency • Mowing of grass filter strips and bioretention turf cover At least 4 times a year • Sot weeding, erosion repair, trash removal, and mulch raking Twice during growing season • Add reinforcement planting to maintain desired the vegetation density • Remove invasive plants using recommended control methods As needed • Stabilize the contributing drainage area to prevent erosion Spring inspection and cleanup p 9 P P • Supplement mulch to maintain a 3 inch layer Annually • Prune trees and shrubs • Remove sediment in re -treatment cells and inflow points Once every 2 to 3 years • Replace the mulch layer Every 3 years BMP PRACTICE DOCUMENTATION NOTE: CONTRACTOR SHALL NOTIFY TIMMONS GROUP FOR PRIOR TO COMMENCEMENT OF CONSTRUCTION OF BMP PRACTICES. A PRECONSTRUCTION MEETING BETWEEN THE DEVELOPER, CONTRACTOR, ENGINEER, INSPECTOR, AND MANUFACTURER IS HIGHLY RECOMMENDED PRIOR TO INSTALLATION OF THESE SMW PRACTICES TO ENSURE THESE PRACTICES ARE NOT ONLY INSTALLED CORRECTLY, BUT ALSO PROPERLY DOCUMENTED THROUGHOUT CONSTRUCTION. IT IS THE CONTRACTORS SOLE RESPONSIBILITY TO DOCUMENT THE INSTALLATION OF THESE PRACTICES. IF THEY PROCEED WITHOUT DOING SO, IT IS DONE AT THEIR OWN RISK. CONTRACTOR SHALL TAKE NOTES, PICTURES, AND MEASUREMENTS OF ALL SUB STRATA LAYERS WITHIN THE BIORETENTION FACILITY DURING CONSTRUCTION THAT CANNOT BE SURVEYED OR VERIFIED POST CONSTRUCTION. IT IS HIGHLY RECOMMENDED TO USE THIS LEVEL OF DETAIL FOR ALL SWM MEASURES BEING INSTALLED IN ADDITION TO THIRD PARTY INSPECTIONS/REPORTS. WITHOUT DOCUMENTING TO THIS LEVEL OF DETAIL, THE CONTRACTOR RUNS THE RISK OF DIGGING THE FACILITIES UP POST CONSTRUCTION TO PROVE THE CORRECT SECTIONS AND SPECIFICATIONS WERE INSTALLED. TOP OF BIORETENTION BASIN 655.00 T HARDWOOD BARK MULCH BOTTOM ELEV 654.75 42" BIOFILTER MIX BOTTOM ELEV 651.25 3" NO. 8 STONE TOP ELEV 651.00 15" NO. 57 STONE SCHEDULE40 PVC UNDERDRAIN ELEV. 649.75 MIRAFI 140N FILTER FABRIC OR EQUIVALENT. TO BE 2' WIDE CENTERED ON UNDERDRAIN GEOTEXTILE TO MEET TABLE 9.6 OF THE BIORETENTION MATERIAL SPECIFICATIONS FOR GEOTEXTILE/LINERS SWM-B- LEVEL 2 BIORETENTION CROSS SECTION FLOW FROM FOREBAY PRETREATMENT CELL " #57 STONE 1:1 SIDE MARAFI140N SLOPE FILTER FABRIC OR EQUIVALENT PRETREATMENT II - DISSIPATER CELL DETAIL FOR LEVEL 2 BIOFILTER REQUIREMENT No Scale Pre -Construction Meeting ❑ Pre -construction meeting with the contractor designated to install the bioretention practice has been conducted. ❑ Identify the tentative schedule for construction and verify the requirements and schedule for interim inspections and sign -off. ❑ Subsurface investigation and soils report supports the placement of an bioretention practice in the proposed location. ❑ Impervious cover has been constructed/installed and area is free of construction equipment, vehicles, material storage, etc. ❑ All pervious areas of the contributing drainage areas have been adequately stabilized with a thick layer of vegetation and erosion control measures have been removed. ❑ Area of bioretention practice has not been impacted during construction. ❑ Stormwater has been diverted around the area of the bioretention practice and perimeter erosion control measures to protect the facility during construction have been installed. . Excavation ❑ Compare the bioretention surface and invert design elevations with the actual constructed elevations of the inflow and outlet inverts and adjust design elevations as needed. ❑ Area of bioretention excavation is marked and the size and location conforms to plan. ❑ If the excavation area has been used as a sediment trap: verify that the bottom elevation of the proposed stone reservoir is lower than the bottom elevation of the existing trap. ❑ For Level 2 bioretention, ensure the bottom of the excavation is scarified prior to placement of stone. ❑ Subgrade surface is free of rocks and roots, and large voids. Any voids should be refilled with the base aggregate to create a level surface for the placement of aggregates and underdrain (if required). ❑ No groundwater seepage or standing water is present. Any standing water is dewatered to an acceptable dewatering device. ❑ Excavation of the bioretention practice has achieved proper grades and the required geometry and elevations without compacting the bottom of the excavation. ❑ Certification of Excavation Inspection: Inspector certifies the successful completion of the excavation steps listed above. Filter Layer, Underdrain, and Stone Reservoir Placement ❑ All aggregates, including, as required, the filter layer (choker stone & sand), the stone reservoir layer or infiltration sump conform to specifications as certified by quarry. ❑ Underdrain size and perforations meet the specifications. ❑ For Level 2 installations: placement of filter layer and initial lift of stone reservoir layer aggregates with underdrain or infiltration sump, spread (not dumped) to avoid aggregate segregation; or ❑ Impermeable liner, when required, meets project specifications and is placed in accordance with manufacturers specifications. ❑ Sides of excavation covered with geotextile, when required, prior to placing stone reservoir aggregate; no tears or holes, or excessive wrinkles are present. ❑ Placement of underdrain, observation wells, and underdrain fittings (45 degree wyes, cap at the upstream end, etc.) are in accordance with the approved plans. ❑ Elevations of underdrain and outlet structure are in accordance with approved plans, or as adjusted to meet field conditions. ❑ Placement of remaining lift of stone reservoir layer as needed to achieve the required reservoir depth. ❑ Certification of Filter Layer and Underdrain Placement Inspection: Inspector certifies the successful completion of the filter layer and underdrain placement steps listed above. Bioretention Soil Media Placement ❑ Soil media is certified by supplier or contractor as meeting the project specifications. ❑ Soil media is placed in 12-inch lifts to the design top elevation of the bioretention area. Elevation has been verified after settlement (2 to 4 days after initial placement). ❑ Side slopes of ponding area are feathered back at the required slope (no steeper than 3H: l V). ❑ Certification of Soil Media Placement Inspection: Inspector certifies the successful completion of the soil media steps listed above. Pretreatment and Plant Installation ❑ Placement of energy dissipators and pretreatment practices (forebays, gravel diaphragms, etc.) are installed in accordance with the approved plans. ❑ Riser, overflow weir, or other outflow structure is set to the proper elevation and functional; or. ❑ External bypass structure is built in accordance with the approved plans. ❑ Appropriate number and spacing of plants are installed in accordance with the approved plans. ❑ All erosion and sediment control practices have been removed. ❑ Follow-up inspection and as -built survey/certification has been scheduled. ❑ GPS coordinates have been documented for all bioretention practice installations on the parcel. ''EALTH OP L7 IEREMYL. FOX Lic. No. 60786 06/14/22 M E O 0 rn � N UI N C > E w o E � w w 3 ¢ a o 3 0 I.L.- w 0 `6 c� W L M d J U o7 wISE J -� aiON to N R U W N � 30 )X J LL � N Ln _ N = U >UD ~ C 0 0 N co � M a� QD Ln M O x c� 0 H 0 w wei 2 U z O 0 r N Z 0 z z w O I-_ U N Z O z U O of w to o. of N > w uJ DATE 0410512022 DRAWN BY J. FOX DESIGNED BY J. FOX CHECKED BY C. SHIFFLETT SCALE M LU M _J z � UJ Lu Q O Ln LU �j z O � z N > 1— MuJ J z < W U 2:w w co O(rj Q _ j w W O C �..QC 1 � G J IY LU Q J H� O Q Li M O JOB NO. 47010 SHEET NO. C2.0 0 d 0 3 a 0 o n0 EN 00 a2 0 c F- m E o no c p, a c a0 Oc t7 3 Z z„ OB � a 02 5 �E0 2 'N CIE dm 7 y X 0.0 L j m o 12 `o d� 0 a c Ma 10 a 0 N 0 ra c c m id id 0 c 0 n o 00 o N d 01 L PLAN VIEW OF PROPOSED GRASS CHANNEL IIC STORMWATER MANAGEMENT & BIORETENTION FACILITIES SCALE: 1" = 20' ` ✓ \ ARRANGE AS -BUILT \ \ OUTFALL RIPRAP AS TMPNECCESSARY TO U/WSWMEASEMENT\`\ UNTAIN55E-PROPE \ \ \ ACHIEVE OUTLET MARCH MOUNTAIN PROPERTIES LLC PROTECTION AT DB 5108 PG 304 \ CHANNEL INLET \ 100' WPO BUFFER \ \ 668 \ \ \ SWM A - 110' LONG 6' WIDE \ 75' STREAM BUFFER LOT ENCROACHMENT \ WETLANDS TRAPEZOIDAL GRASS VARIATION APPROVAL (0310612019) \ CHANNEL @ 4.0% \ SEE DETAIL SHEET C2.0 APPROVED LIMITS OF DISTURBANCE FORWP020180007�\ ENSURE SILT FENCE IS STILL INTACT AND \ \\ \ OPERATIONAL FROM ORIGINAL PLAN. REPLACE OR \ \ \ REPAIR AS NEEDED DOWNSTREAM PRIOR TO BIOFILTER INSTALLATION. \ PROPOSED j FENCE G\ �� TIE TO EXISTING GROUND @ 2:1 SLOPE AS \ \ INDICATED ON APPROVED WPQ. STABILIZE WITH LOW MAINTENANCE VEGETATIVE COVER \ ry W I rr4' h W 8 6S 648 �\\ \ OTHER THAN GRASS. (I.E. SEASONAL NURSE 0 \\ CROP PER VESCH SPEC 3.32 TABLE 3.32-D) / \ TMP 55E-01-32-89 / PRE-TREATMENT FOREBAY W W W W W W66 \\ \ 24" NYLOPLAST BASIN / CRAIG ENTERPRISES INC CLASS Al RIP -RAP W W W W S WITH DOME GRATE TOP @ 655.50 & DB 5625 PG 57 / VOLUME = 645 CF \ " r W W \\� 12" SCH 40 PVC OUTLET TO ED POND /jam v r W SEE DETAIL SHEET C2.0 PRE-TREATMENT#57STONE \ W \` STONE OVERFLOW \ DIAPHRAGM @ 655.50 �� W W W W W WEIR INTO EXISTING \ SEE DETAIL SHEET C2.0 �� \6S6 6S W W W \\ BASIN @ 655.50 \ SWIM B - LEVEL II P W 6" DIAMETER COBBLE @ 1' DEEP BIORETENTION FACILITY W W ro L= 8' TMP 55E-01-32-90 SURFACE AREA = 2,280 SF W= TAPER U TO 10' CRAIG ENTERPRISES INC \ DTOP DE MULCH = T C2.0 B 5613 PG 457 6 SEE DETAIL SHEET C2.0 \ \ � 6" SCH 40 PERFORATED UNDERDRAIN-- ``, SYSTEM WITH CLEANOUTS 20' ON CENTER \ \ SEE DETAIL SHEET C2.0 TMP 55E-01-32-91 CRAIG ENTERPRISES INC \ \ \ \ DB 5566 PG 156 TMP 55E-01-32-92 ,Q \ ORCHARD CORP. DB 5612 PG 294 \ I � TMP 55E-01-32 A MARCH MOUNTAIN PROPERTIES LLC \ \ DB 5208 PG 362 \ \ \ EXISTING TOPOGRAPHY REPRESENTS 2020 FIELD SURVEY BY ROUDABUSH, GALE & ASSOCIATES, INC. // t------------------------- / - / / - -_; l B/SHOPGATE LANE ' / ; ; = / / o SCALE 1"=20' 0 20' 40' LANDSCAPE PLAN PLANT LIST BOTANICAL DESIGNATION QUANTITY COMMON NAME SIZE SPACING NAME BN 2 BETULA NIGRA HERITAGE RIVER 6' HT. 25' O.C. "HERITAGE" BIRCH CO 8 CEPHALANTHUS BUTTONBUSH 18-24" HT. 10' O.C. OCCIDENTALIS CS 7 COMUS SERICEA BAILEY RED TWIG 18-24" HT. 8' O.C. "BAILEYI" DOGWOOD HV 15 HAMAMELIS COMMON 24-36" HT. 15' O.C. VIRGINIANA WITCHHAZEL HIM 15 HIBISCUS CRIMSON -EYED 1 GALLON 3' O.C. MOSCHEUTOS ROSE -MALLOW CONTAINER LLEX RED SPRITE RSW 19 VERTICILLATA 18-24" HT. T O.C. "RED SPRITE" WINTERBERRY LLEX JIM DANDY JDW 6 VERTICILLATA "JIM WINTERBERRY 18-24" HT. 5' O.C. DANDY" VD 10 VIBURNUM ARROWWOOD I 24-36" HT. 10, O.C. DENTATUM VIBURNUM ERNST CONSERVATION SEEDS, INC. ERNMX-180-2 MIX 1 0.5 LBS SOUTHEAST RAIN GARDEN MIX OR EQUAL WATER QUALITY CALCULATIONS VA DCR SWPP Performance Based Water Quality Calculation Procedure Project: ON -Block 32 Locality: Albemarle Co. Date: 4/1/2022 13:45 Step 1 Determine the applicable area (A) and the post -developed impervious cover 1post). Applicable area (A) = I 452152.8 s.f. or 10.380 acres Post -development impervious cover: structures = parking lot = roadway = impervious = or 0.000 acres or 0.000 acres or 0.000 acres or 5.500 acres or 0.000 acres or 0.000 acres Total = 239580 s.f. or 5.500 acres IPOST = (total post- development impervious cover - A) x 100 F 53% Step 2 Determine the average land cover condition (Iwatershed) or the existing impervious cover (lealsting)- Average land cover condition (Iwatashed): Ifthe locality has determined land cover conditions for individual watersheds within its jurisdiction, use the watershed specific value determined by the locality as Iwatershed. O IR2t C[ShL'd /O Otherwise, use the Chesapeake Bay default value: O watershed ° Iwcazersherl= 16% Existing impervious cover (I, ,,t up): Deternurs: the existing impervious cover of the development site ifpresent. Pre -development impervious cover: structures = parking lot = roadway = other Concrete or 0.000 acres or 0.000 acres or 0.000 acres or 0.000 acres or 0.000 acres or 0.000 acres Total = 0 s.f. or 0.000 acres Imisting = (total existing impervious cover - A) x 100 = 0% * The area should be the same as used in STEP 1. Step 3 Determine the appropriate development situation, The site information detemined in STEP 1 and STEP 2 provide enough mfortnstion to deterlmime the appropriate development situation under which the performance criteria will apply. Check U the appropriate development situation as follows: No Situation 1: This consists of ]and development where the existing percent impervious cover (Iesi,iag) is less than or equal to the average land cover condition (Iwatersbed) and the proposed improvements will create a total percent impervious cover (Ipost) which is less than or equal to the average land cover condition ([watershed). False Ipost 53% S Iaatenhea 16% Yes Situation 2: This consists of land development where the existing percent impervious cover (Iehi,ia) is less than or equal to the average land cover condition (Iwatershed) and the proposed improvements will create a total percent impervious cover (Ipost) which i5 greater than the average land cover condition (Iwatersied). True IexbmigF--0% Jig loxterdked F 16% and True Ipow 53% > Io.o,olhee 16% No Situation 3: This consists of land development where the existimg percent unpervious cover (Iexinrud is Weather than the average land cover condition (Iwatershed). False i<rrsung� > Iuatetshea 16% No Situation 4: This consists of laud development where the existing percent impervious cover (Iexrstrad is served by an existing stombvater management BMP(s) that addresses water quality. Ift]e proposed development meets the criteria for development Situation 1, than the low density development is considered to be the BMP and no pollutant removal is required The calculation procedure for Situation 1 stops here. Ifthe proposed development meets the criteria for development Situations 2, 3, or 4, then proceed to STEP 4 on the appropriate worksheet. VA DCR SWPP Performance Based Water Quality Calculation Procedure SITUAnoN2 Time Iermma 0% Si,, ... rrhd 16% Pmlect. OWEIock 32 and Locality. Albemarle Co. Time I oar 53% Ieuenh,E 16% Date: 01Apr.22 SulATmx 3 Summary ofskuation 2 crieria: from calculation procedu m STEP 1 Win STEP 3. Worksheet r: False Iexlum e% � 4.,..hea I18% Area= 70 36 ac. post-- 53% I wa[emhed= 16% l existing- 0% SIItiATI014 False Ieaunae BMP CURRENTLYIN i PLACE? NO Step 4 Determine the relative pre -development pollutant load (Lpe). Base! on Existing Impervious Caen I Lpre(e:n.a"r) _ [0.05 + (0.009 x l��e)] x A x 2.28 (Equation 516) where: L -am = relative pre -development total phosphorous load (pounds per year) levstieg - F'alaq sne®p avid":cwa(PB®t apracdmwholemmbm) A = applicable area (acres) Lpreoxisa"a)=[0.05+(0.009x 0% )l x lom x228 potrudsperyear 2 Lpre(.e,enhed) _ [0.05 + (0.009 x l,,,,, )] x A x 2.28 (Equation 5-16) i where: Lpre(,a,,xd) =relative pre-devebpment totalphosphorms load (pounds per year) 'W... = avaW last avamndrtim for spm8nwnashd orloaq ortheOaa, ate Bay ddmh viueof16%(pacmt Wroxal a wtolenumxo) A = applicable area (acres) L,00ruenhea)= [0.05 + (0.009 x 16% )I x 10.38 x 2.28 pounds per year Step 5 Determine the relative past development potintant load tea.. LP"., _ [0.05 + (0.009 x Ip"m)] x A x 2.28 (Fyuafion 5-21) where: Lpvm = mlative post -development totalpWsphomm load (pounds per year) ;p ,t = post -development impervious; cover (percent expressed mwhole umbers) A = applicable area (acres) Lpo,r = [0.05 + (0.009 x 53% )] x 10.38 x 2.28 = 1247 pounds per year step Determine the relative pollutant removal requirement (RR). RR = Lppn - (0.9 x LPu(minrng) RR = 12.5 - 1.1 RR= 11.40 pounds per year or RR = L'.u-Lp,x(wum:bea) RR = 12.5 - 4.6 RR= 7.88 pounds per you Use RR= 7.88 (lesservnhue) Step 7 Identify best management practice (BMP) for the site. 1. Determine the required po0rram removal efficiency for the site: EFF = (RR : L,n ) x 100 (Equation 5-22) where: EFF = required pollutant removal efficiency RR = poatant nernoval requirenuem (pounds per year) LPon = relative post -development total plosphorom load. Equation 5-21 (pounds per year) 2. select BMP(s) @Table 5-14 and locate on the site Drainage hnpervious Type Efficiency Area(sf) Arce(sf)Descriphon: BMP1: BM1`2: BMP3: BMP4: BMP5: Step 4 Determine the relative pre -development pollutant load (Lpe). Base! on Existing Impervious Caen I Lpre(e:n.a"r) _ [0.05 + (0.009 x l��e)] x A x 2.28 (Equation 516) where: L -am = relative pre -development total phosphorous load (pounds per year) levstieg - F'alaq sne®p avid":cwa(PB®t apracdmwholemmbm) A = applicable area (acres) Lpreoxisa"a)=[0.05+(0.009x 0% )l x lom x228 potrudsperyear 2 Lpre(.e,enhed) _ [0.05 + (0.009 x l,,,,, )] x A x 2.28 (Equation 5-16) i where: Lpre(,a,,xd) =relative pre-devebpment totalphosphorms load (pounds per year) 'W... = avaW last avamndrtim for spm8nwnashd orloaq ortheOaa, ate Bay ddmh viueof16%(pacmt Wroxal a wtolenumxo) A = applicable area (acres) L,00ruenhea)= [0.05 + (0.009 x 16% )I x 10.38 x 2.28 pounds per year Step 5 Determine the relative past development potintant load tea.. LP"., _ [0.05 + (0.009 x Ip"m)] x A x 2.28 (Fyuafion 5-21) where: Lpvm = mlative post -development totalpWsphomm load (pounds per year) ;p ,t = post -development impervious; cover (percent expressed mwhole umbers) A = applicable area (acres) Lpo,r = [0.05 + (0.009 x 53% )] x 10.38 x 2.28 = 1247 pounds per year step Determine the relative pollutant removal requirement (RR). RR = Lppn - (0.9 x LPu(minrng) RR = 12.5 - 1.1 RR= 11.40 pounds per year or RR = L'.u-Lp,x(wum:bea) RR = 12.5 - 4.6 RR= 7.88 pounds per you Use RR= 7.88 (lesservnhue) Step 7 Identify best management practice (BMP) for the site. 1. Determine the required po0rram removal efficiency for the site: EFF = (RR : L,n ) x 100 (Equation 5-22) where: EFF = required pollutant removal efficiency RR = poatant nernoval requirenuem (pounds per year) LPon = relative post -development total plosphorom load. Equation 5-21 (pounds per year) 2. select BMP(s) @Table 5-14 and locate on the site Drainage hnpervious Type Efficiency Area(sf) Arce(sf)Descriphon: BMP1: BM1`2: BMP3: BMP4: BMP5: Grass Swale 1 32 1572516 JIM7712IBMPA BMPB BMPC BMPD BMPE Befliter 90 1572516 IM7712 Extende!D 25 2949012 239580 3. Determine the pollutant load entering the proposed BMP(s): Last = [0.05 + (0.009 x Imp)] x Ap,epana, x 2.28 (Equation 523) where: Lunn, = relative post-dew)Dp7 t totalphosphorous bad entering proposed BMP (pounds per year) Ilo1p = post -development percent mperviom cover ro proposed BMP (percent expressed n lvbob m®bms) AprppaMp = drainage area to proposed BMP (acres) Lgvs, = [0.05 + (0.009 x 70% )1 x 3.61 x 2.28 = 5,58 pounds per year Lmrp, = [0.05 + (0.009 x 70% )1 x 3.61 x 2.28 5,58 pounds per year Loon, =[0.05+(0.o09x 81% )1 x 6.77 x2.28 12.06 pounds per year Luoul = [0.05 + (0.009 x 0% )1 x o60 x 2.28 0.00 pounds per year Lamp,=[0.05+(0.009x 0% )1 x 0.00 x2.28 4. Calculate the pol Mart bad removed by the proposed BMP(s): Lremevea = EffaMp x L,l (Equation 5-24) where: L.­, = post -development totalphosphorom bad removed by proposed BMP (pounds per year) E%w = poatautremovaleffcbocyofBMP(expressed sdecinalfium) Law= relative post-devebpmentnalphosphor s bad entering proposed BMP, Equation 5-23(porndsper year) LrempvedBalPl 7.79 Pounds per year remuvatl Lremo wrBan+ 5.02 Pounds per year amoned I'remo.eaBa1P3 3.07 Pounds per year removed Lremuaea/BaIPI 0.00 Pounds per year removed Lfeme,.,�B381 0.00 Pounds per year annexed 5. Ca culate the total po@tznt bad removed by the BMP(s): Lr... -utetd = L,®ovdd ,+Lr_.vd .W2+Lr__v , .m3+...(Fgmfim5-25) where: i.®,mow = total poarrant bad removed by proposed BMPs (pounds per year) L,®av"paMp, = pollutant bad removed by proposed BMP No. 1, Equation 5-24 L,"aev�2 = pollutant bad removed by proposed BMP No. 2. Equation 5-24 L,m„ev�, = po0ntant bad removed by proposed BMP No. 3, Equation 5-24 Lrema..anma 9.83 Tonal Pounds per year removed 6. Verity compliance: Demo emmt.l >-RR Lrecovdnoul= 9.83 Tdd Pounds par year mooed Req'd Remoel= 7.88 Tdal Pounds per year removed OK, Removal Rate Exceeded IIC STORMWATER MANAGEMENT VV/11 Cr[ 1. ili I I I T I IVIVJ 9VAC25-870-97 STREAM CHANNEL EROSION: Q2YR PRE-DEV = 9.28 CFS (WPO-2018-00077) Q2YR POST-DEV = 7.05 CFS OK Q2YR POST-DEV < Q2YR PRE-DEV 9VAC25-870-89 FLOODING: Q10YR PRE-DEV = 27.36 CFS (WPO-2018-00077) QIOYR POST-DEV = 9.50 CFS OK POST -DEVELOPED Q10 <_ PRE -DEVELOPED Q10 `7 NLTH OP [EREMYL. FOX Lic. No. 60786 06/14/22 'A� M E O T O N UI N C > E w ° E Lu Q U"1 3 oU. o wO to^ rYui LM Q JUto W J -'n d� Or`r Lu N U W w � z~'x 0 LL X v ti _ N = U >to F c '^ O ON N Nco M a� uo H H Z Z W O E a_ of W Z) 0 O Z U O w In c- LU � N w of DATE 0410512022 DRAWN BY J. FOX DESIGNED BY J. FOX CHECKED BY C. SHIFFLETT SCALE AS SHOWN z UJ (1) O L W Q Q a O U Q Z �z (� Q N > M LL CL CL CL az U 2:W w Om� J LL LLI J o C° a z W o Q (D Lu H� Q OrI^) V 1 M J O JOB NO. 47010 SHEET NO. C2.1 0 SCALE 1"=20' 00 0 20' 40' L AM