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WPO201900025 Calculations WPO VSMP 2019-06-19
1 (441( )TERRA ENGINEERING AND 2374 STUARTS DRAFT HIGHWAY,STUARTS DRAFT,VA 24477 LAND SOLUTIONS, PCPH (540)337-_4591 FAX (540)337-5291 Innisfree Albemarle County, Virginia WPO/VSMP Drainage Computations and Stormwater Management Report using SCS, 24-hr TR-20 Methodology February 19, 2019 Rev. May 8, 2019 $ tTZ'A tfir iti J VEN L.DR 4 APPROVED de Uc.No 019933 li by the Albemarle County Community De inp ent Department File ajliiij -7 11---------- ilIQNALS14G _ _______ a e,--- RECEIVED MAY 0 9 2019 COMMUNITY DEVELOPMENT PLANNING+CIVIL ENGINEERING LAND SURVEYING WWW TERRAENGINEERING.NET TERRA ENGINEERING AND 2374 S'l'UAR1'S DRAFI HIGHWAY,S'1UAR'1'S DRAFT,VA 24477 1°743)LAND SOLUTIONS, PC P11 (540)337-4591 FAX (540)337-5291 Innisfree Albemarle County, Virginia Drainage Computations and Stormwater Management Report INDEX 19 February 2019 Rev 8 May 2019 1 . Design Point A Pre-Development 2-3 Design Point A Post-Development 4-7 ... Pre & Post-Development, Point A 2-yr Storm 8-11... . Pre &Post-Development, Point A 10-yr Storm 12 Design Point A Comparison Summary& MS-19 13 Kerby Overland Flow Computation(first 200 feet) 14-15 Drainage Area Maps, Pre & Post, Design Point A 16 Grass Channel (Std. No. 3) Time of Concentrations 17 Grass Channel (Std. No. 3) Ground Cover Areas 18-29 Grass Channels Three, 2-yr& 10-yr Storms 30 Grass Channel Summary 31 Drainage Area Map, Grass Channels APPENDIX A 24-hr Rainfall Depths, Runoff Curve Numbers, Hydrologic Soil Groups, Permissible Velocities, Soil Resource Map, Site Soils APPENDIX B Grass Channel (Std. No 3) Section 6: Design Criteria APPENDIX C VRRM Water Quality Worksheet APPENDIX D Kenmare Catch Basin/Roof Leader and Laurel Roof Leader Runoff Computations and Silt Fence Compliance Computations PLANNING+CIVIL ENGINEERING+LAND SURVEYING WWW TERRAENGINEERING.NET t - - - _ -- - - - - - ----7, -fq b ) Et`1 'Z (/o + a 6/ dQ) �� �•� ( Nmevl -I- dW (Sao otv1) S 1%/ e1 • ------ ------ - - - 0 ) i / Q , o- Zl 1 (71— 7-61iv b w) - ,v r 4 l7 +► Cx, V-ST ' 0 _5-17 eg c/JaEI (2c7- 2 -;_""rote .® ) j J-17Z - - - 3 i ) .�S £L 4)/ ( A �/ 17 .�s Cj Z DLO -. ..E '3) ' -i-2/10 GNnoff/ - dlv g2 - © = 5 .."o?/Cf - $/Z -Lx.VN PO' o _s "El 82•Z . 'o - s <= d oYC S' off' /lOO'7 Z _4 a'3 --- ----- --- 1. A 5�2' ' SL')O <-_- M 3 CZN r�7 i+rJ - s,�� cilaY 1 - -- - (5 / 002 142 15b = ! 7/vg'7 7 MI.0 - 1Od /1/ sga i , I ,DES(G,A1 Potivr A / /Al cpF CI,v ce,v-rgA-770,1t F2.0(Al Ro(47-E-7 — Te 1 /7:71)ST peLiEtzfrimeNT 10+60 ve PcE/viti0 _707,- 4- ‘.. vo-r-11 .-7.- qg 8 / Fi_g_ 7 zoo ' _0 VS-eL 1_,03/V FLOW (Gv000 s- ) II 1 14,-1-6347 /3 .51 DA° I /1/416, r 2 o 0 f US b. 5fmiL.E...o w COlve• r1_0(4/ (Pu-croDs) 1 //,,5 1kDro ------') c9 - 0575' i<f/zac'itH)_ 1 jvcx-7 z3 f its6 5 fteer FL.00/ (I : /, $6oe or: colANA/eL) io. 16 5 ' Dizota —?. 0. 1Z i alz_ens ci I iz_ivA/61.. C 2 i4 St-orvE.______„, re, — 1.-avel--- Sri'evi°eft. 1 — -=, 0, °z .. • i! iv ...)‹.7- 1 C4 f lf,cier4 C...4-A0Y3 1L42 5, 4 ' Agor N E--x7- Z/2:1: CA ea-A/AJgc...., (Ar4-rviem 4) (Pr- 5' Pg.°P ---:, To-TA-4 re k o atv 6 co varz (2,7(0 4c) 4 i '1 I m pc-le 2.Isi trleiS La - — I IT 3/52_ SF - --I , (74 0 :ir 1 7 r----1 o (iciloei7) _ _ 33_30 sr Ir..- 0, a , Ac Z4-4.c. L 8- 7 X) 1, C°%0 I ZO) C 10 0 4 06-/ Pa' 0 rovoom _dove.— t,_,/ 9_1 /v ni Pi `7 14% tea )" �i. .- e00!5 --)ib4Y ) --- iS La/ - f.Ncl Jt Z/l 7 S�fi�=JGv cr►tip . b S7 w ,d 2019-02-19, 2-YR TR-20 Pre, Point A Type II 24-hr Rainfall=4 00" Prepared by {enter your company name here} Printed 2/19/2019 HydroCAD® 10 00-20 s/n 03710 ©2017 HydroCAD Software Solutions LLC Subcatchment Al: Design Point A Area Hydrograph 0 Runoff l 1 31 cfs l Type II 24-hr I'i Rainfall=4.00" / 1_ Runoff Area=2.330 ac / Runoff Volume=5,972 cf - Runoff Depth>0.71" Tc=22.5 m i n , CN=59 0 o . f 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 4- 2019-02-19, 2-YR TR-20 Pre, Point A Type 11 24-hr Rainfall=4 00" Prepared by {enter your company name here} Printed 2/19/2019 HydroCAD® 10 00-20 s/n 03710 ©2017 HydroCAD Software Solutions LLC Summary for Subcatchment Al: Design Point A Area Runoff = 1 31 cfs @ 12 20 hrs, Volume= 5,972 cf, Depth> 0.71" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.01-24.01 hrs, dt= 0.04 hrs Type II 24-hr Rainfall=4.00" Area (ac) CN Description * 0 190 98 Impervious - Misc * 0.010 79 50-75% Grass cover, Fair, HSG B * 2 130 55 Woods, Good 2 330 59 Weighted Average 2.140 91 85% Pervious Area 0.190 8.15% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 22 5 Direct Entry, 5 2019-02-19, 2-YR TR-20 Post, Point A Type II 24-hr Rainfall=4.00" Prepared by {enter your company name here} Printed 2/19/2019 HydroCAD® 10 00-20 s/n 03710 ©2017 HydroCAD Software Solutions LLC Subcatchment Al: Design Point A Area Hydrograph 0 Runoff 12 lads Type II 24-h r 2 / Rainfall^4.00" _ Runoff Area=2.760 ac l Runoff Volume=8,591 cf Runoff Depth>0.86" lO / _ _ ....._ Tc=21 .3� min' 1- CN=62 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) 2019-02-19, 2-YR TR-20 Post, Point A Type II 24-hr Rainfall=4.00" Prepared by {enter your company name here} Printed 2/19/2019 HydroCAD® 10 00-20 s/n 03710 ©2017 HydroCAD Software Solutions LLC Summary for Subcatchment Al: Design Point A Area Runoff = 2 13 cfs @ 12.17 hrs, Volume= 8,591 cf, Depth> 0.86" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0 01-24 01 hrs, dt= 0 04 hrs Type II 24-hr Rainfall=4.00" Area (ac) CN Description * 0 240 98 Impervious-Roof * 0 010 98 Impervious- Misc * 0 610 69 50-75% Grass cover,Good, HSG B * 1 900 55 Woods (Good) 2 760 62 Weighted Average 2 510 90.94% Pervious Area 0 250 9 06% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 21 3 Direct Entry, 7 2019-02-19, 10-YR TR-20 Pre, Point A Type II 24-hr Rainfall=6.00" Prepared by {enter your company name here} Printed 2/19/2019 HydroCAD® 10 00-20 s/n 03710 ©2017 HydroCAD Software Solutions LLC Subcatchment Al: Design Point A Area Hydrograph Z 0 Runoff 414cfsJ 4- Type .11 24-hr / Rainfall=6.00" I Runoff Area 2.330 ac 3= Runoff Volume=15,437 cf Runoff Depth>1 .83" - Tc=22.5 min u 2— CN=59 ..err lily ii �iiii iii 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) S 2019-02-19, 10-YR TR-20 Pre, Point A Type II 24-hr Rainfall=6 00" Prepared by {enter your company name here} Printed 2/19/2019 HydroCAD® 10 00-20 s/n 03710 ©2017 HydroCAD Software Solutions LLC Summary for Subcatchment Al: Design Point A Area Runoff = 4 14 cfs @ 12.17 hrs, Volume= 15,437 cf, Depth> 1.83" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0 01-24 01 hrs, dt= 0 04 hrs Type II 24-hr Rainfall=6.00" Area (ac) CN Description * 0 190 98 Impervious- Misc * 0 010 69 50-75% Grass cover,Good, HSG B * 2 130 55 Woods (Good) 2.330 59 Weighted Average 2 140 91.85% Pervious Area 0 190 8.15% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 22 5 Direct Entry, 1 TypeII 24-hr R infall=6 00" 2019-02-19, 10 YR TR-20 Post, Point A a Prepared by {enter your company name here} Printed 2/19/2019 HydroCAD® 10.00-20 s/n 03710 ©2017 HydroCAD Software Solutions LLC Subcatchment Al: Design Point A Area Hydrograph Li Runoff 6- 572 cfs Type 1124-h r 5- Rainfall 6.00" Runoff Area=2.760 ac I Runoff Volume=20,799 cf Runoff Depth>2.08" 3- Tc=22.5 min LL CN=62 2 / H 2 4 6 8 10 12 14 16 18 20 22 24 Time (hours) Io 2019-02-19, 10-YR TR-20 Post, Point A Type II 24-hr Rainfall=6 00" Prepared by {enter your company name here} Printed 2/19/2019 HydroCAD® 10 00-20 s/n 03710 ©2017 HydroCAD Software Solutions LLC Summary for Subcatchment Al: Design Point A Area Runoff = 5 72 cfs @ 12.17 hrs, Volume= 20,799 cf, Depth> 2 08" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.01-24.01 hrs, dt= 0 04 hrs Type II 24-hr Rainfall=6 00" Area (ac) CN Description * 0 240 98 Impervious-Roof * 0 010 98 Impervious- Misc * 0 610 69 50-75% Grass cover,Good, HSG B * 1 900 55 Woods (Good) 2 760 62 Weighted Average 2 510 90.94% Pervious Area 0 250 9 06% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 22 5 Direct Entry, ( i D'ef /%-ii Po_e_Ae7. A (10 44 15 o A1 Stun/v 1,9R/ DESt ( c.) P R e po s-r 8, 7 p/h9. woo/35% , 4 X 'X roTil 4- ,! TOTAL A-g 64 2, 3 3 4 c 2,76 14c rc plirk 4,6441 9 5-( Tc o'Yl; 22. t€5 HyDRoc.00ff CieaceP CovEr2 Desc, /--R&. CA/ / e).S7- /i/ ( C 1M 93 q8 ,*L4 pi 7 9 M/It9ovs (Goot) ) Z. ,Vo/ IZVA10cF DeC/ZEI I I Ser tac. p_r a/LOSS C ifitvivE4.9 /44-)e/444exi 4- P E. Pc's r -z go,v0FF 0.88 cics / c-Fr c4iAlvCci L cA F. eeTH (MS 8 034' iv- 2,1 Ves n 0,04, 171 7:0,00 I 2_ , ' e-X a, L z 20 _ N D oG CpEciPliotes 65 T i''/ice cfrie& O - C6 « f "67 - - � -- - Z�-✓-- � - D.�Z S. _�ZDD �� .D 80, D, GCo7j -- - - ------- --- II 1 \•\'\''' : , ,�� \ ` - EXHIBIT SHOWING \ A\\!t�I � TERRA ENGINEERING ;;- NDRAINAGE AREAS FOR 1 �I\`���I� " '\ .,. AND / DESIGN POINT "A" -- - -� `�� ' LAND SOLUTIONS, PC / PRE DEVELOPMENT '�,�\� PLANNING /" / I I J \��\ LAND SURVEYING II o I I ' �t,l����� CIVIL ENGINEERING — / I ! 'J I/l� 2374 STUARTS DRAFT HIGHWAY '\'�0 / WOODS i 1 I 1 oI , I 1 {,l .�ll STUARTS DRAFT',VIRGINIA 24477 / , , 719/A/��iPH.540-337-4591 FAX 540-337-5291 _ e;• / ..'i:;z. T�PATH d;,,/ ���/8////I 111�//II71/' %/' I•i . i`• � 1 r l /1""' !! ' 0 Qa '` :'•i;: a:ANti:: I /lllllll iPOINT"A"! 12- �� l IMPERMEABLE MISC L *9 <:-. I J/ i,//411f/iffihifl ���11./!l; I N, • \\ . „l / 1 _ ; ; ,� ,# ::. 0.;; :::: : ( �f�/ / ///// !rl/ 111/ ,,. \ ���� V „ q5 , r. '/ ! , / , •/�r,. T . �\\�\� \\\� \\fi `/ TWO D \. / �� — r Toss ,�� \ \ � ,\ _� _ GRASS � ` N,DRAINAGE AREAS - - , ,, 4 ...,..,:Aa..: '� '.:>•s:, -.... IMPERMEABLE MISC\ \ � .� DESCRIPTION SIZE (AC.) `� = :': : ,.,,,,....1\\‘‘ .-'%\\\\‘ . IMPERMEABLE MISC 0.19 _ IMPERMEABLE-MISC t� t \\ / 8��.� eer' 1J'- / r� '� ��:.- �'~\ LAWN 0 01 r.. , J i„ , „go . L I►�s �y \ �� \ O��^ .mac "� ,.1, _LOII �' \ 2 OPEN SPACE 2 13 i'` -1_1 - \\ l J -�' �� ;* TOTAL 2 33 = �' - _ 4. 1 1C GRAPHIC SCALE �, 1065/ / / / I 100 0 50 100 200 ' ���' f In ,ir i ( IN FEET ) / =� 1 inch = 100 ft ,�55 f 6R/463 CHAAINEL. Tc_ iclogm ck/f/vAie-c_ — xeme_g_ic& "Tc = LS.Z3 CE DEvEc. - Fag- ecvAirig ) NH C144NNE L. — /LAtie& Fig _7- 27 I) PROP o_fic' 0 -0z2 v . /3 fk/E-xT /4 / ) _pizot° 0.14 NE--)er / '3 ', Dgop cot = 0. 05-3 17 N EY T /9 pgoe 2,5f vr7 0- /3 4 '(e-04 5 5 CHAVA/E0 • Z 2, 8 2 Z7 To-Of C FLoui 1...e4'ar771 6.1.56 5/141, / ) SOUTH C AtChiftt. - 4-4-41-ZCL lip FIRST 5311 DRDPO ,7 ° 2. 3 ° /3 A/6)a- /4/ DieOP :17 ) o • let a ?4, Aivx7 107 / DAVI' o, e6" Cep 0. 13 ___A/ T / o () t),eOf L' 0 . /6 _ bicZ izz (Gg,t1scHiaavNE-L) 2. 12 / TOTN-L FLaw z &A/aTH z.456. 5 ,v) Lf J.. oL V gz'o Sdoo✓til b o 1 ' a S / 1 sr ( 2' v J) 0 62 'O /00 ti_BLL b' 23 7—0- '7O0M -)d L a Q dS - cdie/ JSiw Dv 2-o0 - Js Zc-1 .-400 0 '0 = _SS loch yh y7 _ � 9/ 7V/1 fJ_1 u o rJ V moo '/ dQO4N4, frt $% - o w/ OS)le z 00'd = is o El r 1a+.3a►b' 13rti/Vt/J/D S sa> 2019-02-19, Kenmare, N Grass Channel 2-yr Storm Type II 24-hr Rarnfall=4.00" Prepared by {enter your company name here} Printed 2/19/2019 HydroCAD® 10 00-20 s/n 03710 ©2017 HydroCAD Software Solutions LLC Subcatchment 4: Grass Channel - Kenmare North Hydrograph . 0 Runoff 1.1_15cfs 'Type II 24-hr 1- • RainfaiI=4.00" Runoff Area=1 .062 ac Runoff Volume=3,965 cf Runoff Depth=1.03" LL I Tc=18.,2 min CN=65 • • 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 Time (hours) I5 2019-02-19, Kenmare, N Grass Channel 2-yr Storm Type 11 24-hr Rainfall=4 00" Prepared by {enter your company name here} Printed 2/19/2019 HydroCAD® 10 00-20 s/n 03710 ©2017 HydroCAD Software Solutions LLC Summary for Subcatchment 4: Grass Channel - Kenmare North Runoff = 1 15 cfs @ 12 12 hrs, Volume= 3,965 cf, Depth= 1 03" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0 01-48 00 hrs, dt= 0.01 hrs Type II 24-hr Rainfall=4 00" Area (ac) CN Description * 0.680 60 Woods, Fair * 0 310 69 50-75% Grass cover, Fair, HSG B * 0 070 98 Roof * 0 002 98 Mlsc Imp 1 062 65 Weighted Average 0.990 93.22% Pervious Area 0.072 6 78% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 18 2 Direct Entry, I 2019-02-19, Kenmare, N Grass Channel 10-yr Storm Type 1124-hr Rainfall=6.00" Prepared by {enter your company name here} Printed 2/19/2019 HydroCAD® 10 00-20 s/n 03710 ©2017 HydroCAD Software Solutions LLC Subcatchment 4: Grass Channel - Kenmare North Hydrograph I Runoff 3— l 287cfs•i j Type II 24-hr Rainfall=6.00" Runoff Area=1 .062 ac 2- Runoff Volume=9,064 cf w Runoff:Depth=2.35" �. LL Tc=18.2 min CNT65 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 Time (hours) 20 2019-02-19, Kenmare, N Grass Channel 10-yr Storm Type II 24-hr Rainfall=6 00" Prepared by {enter your company name here} Printed 2/19/2019 HydroCAD® 10 00-20 s/n 03710 ©2017 HydroCAD Software Solutions LLC Summary for Subcatchment 4: Grass Channel - Kenmare North Runoff = 2.87 cfs @ 12 11 hrs, Volume= 9,064 cf, Depth= 2 35" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0 01-48 00 hrs, dt= 0 01 hrs Type II 24-hr Rainfall=6 00" Area (ac) CN Description * 0 680 60 Woods, Fair * 0.310 69 50-75% Grass cover, Fair, HSG B * 0.070 98 Roof * 0 002 98 Mlsc Imp 1.062 65 Weighted Average 0.990 93 22% Pervious Area 0 072 6 78% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 18 2 Direct Entry, 2. 1 2019-02-19, Laurel, N Grass Channel 2-YR Strom Type II 24-hr Ra,nfall=4 00" Prepared by {enter your company name here} Printed 3/8/2019 HydroCAD® 10 00-20 s/n 03710 ©2017 HydroCAD Software Solutions LLC Subcatchment 4: Grass Channel - Laurel North Hydrograph 042^ U Runoff` 04- 10.38 cis,' 038_ 0 3 Type I-1 24-h r 034= RainfalI=4.00" 032= °3, Runoff Area=O.183 ac 028 026= Runoff Volume=759 cf 024', g °oz- Runoff Depth>1 .14" tr. 0 1 - Tc=5.0 min 0 16= 014? CN=67 012- 0 1i 0 006= 004 0 02i 0. �.... ..., ,., i.. .i,.. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) 2019-02-19, Laurel, N Grass Channel 2-YR Strom Type II 24-hr Rainfall=4 00" Prepared by {enter your company name here} Printed 3/8/2019 HydroCAD® 10.00-20 s/n 03710 ©2017 HydroCAD Software Solutions LLC Summary for Subcatchment 4: Grass Channel - Laurel North Runoff = 0.38 cfs @ 11.97 hrs, Volume= 759 cf, Depth> 1.14" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0 01-24 00 hrs, dt= 0.01 hrs Type II 24-hr Rainfall=4 00" Area (ac) CN Description * 0 090 69 50-75% Grass cover, Good, HSG B * 0 020 98 Roof * 0.003 98 Misc Imp * 0 070 55 Woods (Good) 0.183 67 Weighted Average 0.160 87 43% Pervious Area 0 023 12.57% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5 0 Direct Entry, 23 2019-02-19, Laurel, N Grass Channel 10-YR Strom Type II 24-hr Rainfall=6.00" Prepared by {enter your company name here} Printed 3/8/2019 HydroCAD® 10 00-20 s/n 03710 ©2017 HydroCAD Software Solutions LLC Subcatchment 4: Grass Channel - Laurel North Hydrograph 0 95� . . _ ❑Runoff 09� . - . - .1086cfs I 0 85= r✓ Type- 1124-hr 0075 ✓ --. Rainfall=6.00" Runoff Area=O:183 ac 0 65i 06= Runoff Volume=1 ,678 cf w 0 55,. ✓ 054, Runoff Depth>2.53" °45- Tc=5.0 m i n 04= 0 35= ✓-- CN=67 0 3= 0 25= 0 27 015= 01: 005= 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) 24 r ll=4 00" 2019 02 19, Laurel, S Grass Channel 2-yr Storm Type 11 24-h r Ra nfa Prepared by {enter your company name here} Printed 3/8/2019 I HydroCAD® 10 00-20 s/n 03710 ©2017 HydroCAD Software Solutions LLC Subcatchment 4: Grass Channel - Laurel North Hydrograph 0 6- ❑Runoff . : 1056a:I 0 55-. ; Type II 24-hr 05 - Rainfall-4.00." 045_ Runoff Area=0.288 ac 04- Runoff Volume=1 ,114 cf w 0 35- l Runoff:Depth>1 .08" 0 0 3- Tc=5.0 min 0 25- GN=66 0 2- 0 15- 01- 005- 0 .. .. i .. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) .6/ 2019-02-19, Laurel, S Grass Channel 2-yr Storm Type 11 24-hr Rainfall=4.00" Prepared by {enter your company name here} Printed 3/8/2019 HydroCAD® 10 00-20 s/n 03710 ©2017 HydroCAD Software Solutions LLC Summary for Subcatchment 4: Grass Channel - Laurel North Runoff = 0.56 cfs @ 11.97 hrs, Volume= 1,114 cf, Depth> 1 08" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.01-24.00 hrs, dt= 0.01 hrs Type II 24-hr Rainfall=4 00" Area (ac) CN Description * 0 160 69 50-75% Grass cover, Good, HSG B * 0 020 98 Roof * 0.003 98 Misc Imp * 0 100 55 Woods (Good) 0 283 66 Weighted Average 0 260 91.87% Pervious Area 0 023 8 13% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5 0 Direct Entry, 7 2019-02-19, Laurel, S Grass Channel 10-yr Storm Type Il 24-hr Rainfall=6.00" Prepared by {enter your company name here} Pnnted 3/8/2019 HydroCAD® 10 00-20 s/n 03710 ©2017 HydroCAD Software Solutions LLC Subcatchment 4: Grass Channel - Laurel North Hydrograph 0 Runoff l 1 29 cfs Type II 24-hr / Rainfall=6.00" 1 Runoff Area=0.283 ac Runoff Volume=2,603 cf N r Runoff;Depth>2.44" LL Tc=5.0 m i n CN=66 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) 28 1 2019-02-19, Laurel, S Grass Channel 10-yr Storm Type II 24-hr Rarnfall=6 00" Prepared by {enter your company name here} Printed 3/8/2019 HydroCAD® 10 00-20 s/n 03710 ©2017 HydroCAD Software Solutions LLC Summary for Subcatchment 4: Grass Channel - Laurel North Runoff = 1.29 cfs @ 11 96 hrs, Volume= 2,503 cf, Depth> 2.44" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0 01-24 00 hrs, dt= 0.01 hrs Type II 24-hr Rainfall=6.00" Area (ac) CN Description * 0 160 69 50-75% Grass cover, Good, HSG B * 0 020 98 Roof * 0 003 98 Misc Imp * 0.100 55 Woods (Good) 0 283 66 Weighted Average 0.260 91 87% Pervious Area 0 023 8.13% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5 0 Direct Entry, 29 - - -- 4-Lc- TH-g_tE 672. ss_ c'AligNNEcS 1L sc dp 07, - - - FLovi DERV/ of < 3 `r ro-re L N eD4- _AAA. 4 w 10 5 s o T, ki/ 4 : / 5/,A- 3 Flow vEL — Z Yn toYR 2 Yid to Y/2 / €f 7Ai /./5 c 'g .2, S7cF5 2.2i o,/Z 3./) o.20 4A-1.42EL, BLT f Q B cis a 86 Cb /. 5 0,off 2.1, 0,10 4.r4_YZ e-e- rN 0.5a c4 1. 21 cg• 1.7) o..ag 24, o, 13 7-74r3c.e 3.3) AL . CAVA NIN GS ca v ZE Caitip/z/5_c-q grit' 4",f vE ' T7i°. titre-i7 eic CEPT /< _a/L?H__ 01#(cpi fYfreG uM& ,14 fr7v2 E Ami .F=/LetslaOA Rt.;� K_C-Avii d, /-0"7 77f f o-5o = o • 70 L. mac- ,vo ,T7/ =? o , r0 -1 o •s0 o . t� s tau r-/ = / (3 + a.W = 0, 6.3 / FLO rw S -L(.S e/) 26,5 OeX/c 77/4 ✓= a.4g8 45 -�mr o.oz.ci; - KEN 1"LE No�.�r� => f` 3 __DuE 7-HE sm,eu. D, r_IL/4a c-_AeF 1.4-u z--- `�✓vr�Tt�' =� A / 'g,.,qt-i, Le__ Er /,++PE/2ce-PTA 6'45 ..� ,--.r/Lat— Svu rrf =7 /2 2 _±- wive cm, A/A,E- .s Atts 4155_p 72La T F! o 40 O iv_ 5 /.G i - - ---- .A- l I,RA/N_w/yG vo'4K__/ _ago vie - Tk'E y2G-'/PEwca-n,rle- fix U/,gm'2 _.$vA-L/T /S 41S17. \ \ \ \ — `y''�}` ;11'I' �' \TERRA ENGINEERING / DRAINAGE AREA MAP _ ��,4,�,�� 4 AND ,oi / _ ;��������� ),I/LAND SOLUTIONS, PC "'`��� PLANNING / ' �4, I �♦III ���Ph LAND SURVEYING CIVIL ENGINEERING � ..../..--. �� 1?) NN°� . - / woogs I i -• 2374 STUARTS DRAFT HIGHWAY / 5 } KENMARE STUARTS DRAFT,VIRGINIA 24477 1)1/ PH.540-337-4591 FAX 540-337-5291 h8 i / NORTH CHANNEL Tc PATH I (1 06 AC DRAINAGE AREA) J. J lII Jf ,,Q, \ ��t- �s5'`% v_` ; "��� 11 /li i j'-1 " �= 1 0 •, '�3'� 4ff4 // /� 1 i�'= \ \\ — - '%9' �r ��1l/ MISC �l OKIF.1 � I I � �` ' r `•.C - _ ,�?���d;:!< i►w���. '///r/•G IMPERMEABLE • 1 � ( �- \ \ �/ 4 0. _5 --IY/4 4 �� ,� �.,�/A p �l---. / / / tgiglik. ..*: -, - �'~� �`; `, .., .,.,e.s....tp.if '''* * \ '\\ .-. . s:. , --,, ,--•,- -:._:_____-_____--=,--T-_- _--_1-:,---,--- .. • . \ \\a O �20 AC +� � w.��/�I`� Tc PATH /� p. LAUREL ��`'� `\\ \ >� \� � .- i : `kill .". I s) i� NORTH CHANNEL :'. - �\� � A KENMARE W .�. (0 18 AC DRAINAGE AREA) ' .. `\`�.,. ` �.� 5 ROOF - ► �� ppp, ,ii''.. \.�'"vS �� ` � ' � � KENMARE - NORTH CHANNEL , �S , %.,f0-� \. \ \ "��\ �'90 ��' ��1� �� ' MISC \ DESCRIPTION SIZE (AC.) Tc PATH; r OS .��'/.'�q 0'� = �.•'"like '" IMPERMEABLE _--- 6* .1,k.- ri-GRASS 0 31 ss��'„ •,,,*'' '4.. _ ROOF 0 07 F ���•o� ,y�� • MISC IMPERMEABLE 0 002 � %��'R LAUREL o 1 \ \ N - .`ham .3< '.•��; f� ROOF - -. e WOODS 0.68 A' LAUREL �/ ����w�- f �" ter L�• SOUTH CHANNEL '� `lifer _, ---- 44 .r a - -- �/ I , TOTAL 1.06 (0 28 AC DRAINAGE AREA) - ¢�- - / I I - - , LAUREL- NORTH CHANNEL LAUREL - SOUTH CHANNEL f u` - - I I' DESCRIPTION SIZE (AC) DESCRIPTION SIZE AC " I I GRASS 0 09 GRASS 0 16 GRAPHIC SCALE ROOF 0 02 ROOF 0 02 100 0 50 100 200 MISC IMPERMEABLE 0 003 MISC IMPERMEABLE 0.003oiewm WOODS 0 07 WOODS 0 10 ( IN FEET) TOTAL 0.18 TOTAL 0.28 J 1 inch = 100 ft 3/ Appendix A HYDROLOGIC METHODS APPENDIX 4B 24 HOUR RAINFALL DEPTHS YEAR COUNTY 1 2 5 10 25 50 100 Accomack 3.0 3.7 4.9 6.0 6.8 7.5 8.5 Albemarle 3 3 4 0 5 0 6.0 7.0 8.0 8.5 Alleghany 2.5 3.0 4.0 5.0 5.5 6.0 7.0 Amelia 3.0 3.5 4.5 5.5 6.0 7.0 7.5 Amherst 3 3 4 0 5 0 6.0 7 0 8 0 8 5 Appomattox 3.0 4.0 4.7 5.8 6.2 7.0 8.0 Augusta 3 0 4 0 4.5 5 5 6.5 7.2 8.0 Bath 25 3.0 40 50 55 60 70 Bedford 3.3 4.0 5.0 5.8 6.8 7 5 8 2 Bland 24 29 39 46 50 58 60 Botetourt 3.0 3.5 4.5 5.0 6.0 7.0 7.8 Brunswick 3 0 3 5 4 6 5 6 6 2 7 0 8 0 Buchanan 2.4 2.9 3.7 4.3 4.8 5.5 6.2 Buckingham 3.0 3.5 4.7 5.8 6.3 7.0 8.0 Campbell 3.0 3.7 4.7 5.8 6.3 7.0 7.9 Caroline 2.7 35 45 55 60 68 77 Carroll 2.8 3.2 4.0 4.9 5.2 6.0 6.8 Charles City 30 35 45 5.5 62 70 79 Charlotte 3.0 35 4.5 55 60 70 77 Chesapeake 3 2 3 8 5 1 6 0 7.0 8 0 8.9 Chesterfield 30 39 45 55 60 70 76 Clarke 27 31 45 50 60 70 76 4B - 1 Table 2-2a.—Runoff curve numbers for urban areas' Curve numbers for Cover description hydrologic soil group— Average percent Cover type and hydrologic condition impervious area2 A B C D Fully developed urban areas (vegetation established) Open space (lawns, parks, golf courses, cemeteries, etc.)3: Poor condition (grass cover < 50%) 68 79 86 89 Fair condition (grass cover 50% to 75%) 49 69 79 84 Good condition (grass cover > 75%) 39 61 74 80 Impervious areas: Paved parking lots, roofs, driveways, etc. (excluding right-of-way) 98 98 98 98 Streets and roads: Paved; curbs and storm sewers (excluding right-of-way) 98 98 98 98 Paved; open ditches (including right-of-way) 83 89 92 93 Gravel (including right-of-way) 76 85 89 91 Dirt (including right-of-way) 72 82 87 89 Western desert urban areas: Natural desert landscaping (pervious areas only r... 63 77 85 88 Artificial desert landscaping (impervious weed barrier, desert shrub with 1- to 2-inch sand or gravel mulch and basin borders). 96 96 96 96 Urban districts: Commercial and business 85 89 92 94 95 Industrial 72 81 88 91 93 Residential districts by average lot size: 1/8 acre or less (town houses) fi5 77 85 90 92 1/4 acre 38 61 75 83 87 1/3 acre 30 57 72 81 86 1/2 acre 25 54 70 80 85 1 acre 20 5I 68 79 84 2 acres 12 46 65 77 82 Developing urban areas Newly graded areas (pervious areas only, no vegetations 77 86 91 94 Idle lands (CN's are determined using cover types similar to those in table 2-2c). AAverage runoff condition, and I, = 0.28 2The average percent impervious area shown was used to develop the composite CN's Other assumptions are as follows: impervious areas are directly connected to the drainage system,impervious areas have a CN of 98,and pervious areas are considered equivalent to open space in good hydrologic condition. CN's for other combinations of conditions may be computed using figure 2-3 or 2.4. 3CN's shown are equivalent to those of pasture. Composite CN's may be computed for other combinations of open space cover type. 4Composite CN's for natural desert landscaping should be computed using figures 2-3 or 2-4 based on the impervious area percentage(CN = 98)and the pervious area CN The pervious area CN's are assumed equip alent to desert shrub in poor hydrologic condition 'Composite CN's to use for the design of temporary measures during grading and construction should be computed using figure 2 3 or 2-0, based on the degree of development (impervious area percentage)and the CN's for the newly graded pervious areas. (210-VI-TR-55, Second Ed., June 1986) 2-5 Table 2-2b.—Runoff curve numbers for cultivated agricultural lands' Curve numbers for Cover description hydrologic soil group— Hydrologic Cover type Treatment2 condition3 A B C D Fallow Bare soil — 77 86 91 94 Crop residue cover (CR) Poor 76 85 90 93 Good 74 83 88 90 Row crops Straight row (SR) Poor 72 81 88 91 Good 67 78 85 89 SR + CR Poor 71 80 87 90 Good 64 75 82 85 Contoured (C) Poor 70 79 84 88 Good 65 75 82 86 C + CR Poor 69 78 83 87 Good 64 74 81 85 Contoured & terraced (C&T) Poor 66 74 80 82 Good 62 71 78 81 C&T + CR Poor 65 73 79 81 Good 61 70 77 80 Small grain SR Poor 65 76 84 88 Good 63 75 83 87 SR + CR Poor 64 75 83 86 Good 60 72 80 84 C Poor 63 74 82 85 Good 61 73 81 84 C + CR Poor 62 73 81 84 Good 60 72 80 83 C&T Poor 61 72 79 82 Good 59 70 78 81 C&T + CR Poor 60 71 78 81 Good 58 69 77 80 Close-seeded SR Poor 66 77 85 89 or broadcast Good 58 72 81 85 legumes or C Poor 64 75 83 85 rotation Good 55 69 78 83 meadow C&T Poor 63 73 80 83 Good 51 67 76 80 'A%erage runoff condition,and I;, = 02S 2Crnq, res,dsie corer applies only if residue is on at least 5eA of the surface throughout the year. 1Hvdrulogx cYn d ition is based on combination of factors that affect infiltration and runoff, including(a)density and canopy of vegetative areas,(b)amount of year-round cohei,(c)amount of grass or close-seeded legumes in rotations,(d)percent of residue cover on the land sue face(good > 2O'',),and(e)degree of surface roughness Poo): I•acturs impair infiltration and tend to increase runoff Good- Factor,encourage average and better than a%erage infiltration and tend to decrease runoff. 2-6 (210-VI-TR-55, Second Ed., June 1986) i I Table 2-2c.—Runoff curve numbers for other agricultural lands' Curve numbers for Cover description hydrologic soil group— Hydrologic Cover type condition A B C D Pasture, grassland, or range—continuous Poor 68 79 86 89 forage for grazing.2 Fair 49 69 79 84 Good 39 61 74 80 Meadow—continuous grass, protected from — 30 58 71 78 grazing and generally mowed for hay. Brush—brush-weed-grass mixture with brush Poor 48 67 77 83 the major element.' Fair 35 56 70 77 Good 430 48 65 73 Woods—grass combination (orchard Poor 57 73 82 86 or tree farm).5 Fair 43 65 76 82 Good 32 58 72 79 Woods.' Poor 45 66 77 83 Fair 36 60 73 79 Good 430 55 70 77 Farmsteads—buildings, lanes,-driveways, — 59 74 82 86 and surrounding lots. 1Average runoff condition,and L, = 0.2S. PPoor: <50% ground cover or heavily grazed with no mulch Fun•. 50 to 75% ground corer and not hea%ii grazed. Good >757/ ground cover and lightly or unl, occasionally grazed. 3Nuu, <50'k ground cover. Fa i r. 50 to 757r ground co\er Good >75% ground cover. 'Actual curve number is less than 30, use CN = 30 for runoff computations. a • * . - r4 xoods and 507� grass(pasture)cover Other combinations of conditions may be computed GA �shim n x ere computed fur areas x rth 50 from the CN's for goods and pasture. 61'uur• Forest litter, small trees, and brush are destroyed by heavy grazing or regular burning Fifer. Woods are grazed but not burned,and some forest litter covers the soil. Good• Woods are protected from grazing, and litter and brush adequately cover the soil. (210-VI-TR-55, Second Ed., June 1986) 2-7 Appendix A: Hydrologic soil groups Soils are classified into hydrologic soil groups In exhibit A-1, some of the listed soils have an added (HSG's) to indicate the minimum rate of infiltration modifier; for example, "Abrazo, gravelly." This obtained for bare soil after prolonged wetting. The refers to a gravelly phase of the Abrazo series that HSG's, which are A, B, C, and D, are one element is found in SCS soil map legends. used in determining runoff curve numbers (see chapter 2). For the convenience of TR-55 users, exhibit A-1 lists the HSG classification of United Disturbed soil profiles States soils. The infiltration rate is the rate at which water As a result of urbanization, the soil profile may be enters the soil at the soil surface. It is controlled by considerably altered and the listed group surface conditions. HSG also indicates the classification may no longer apply. In these transmission rate—the rate at which the water circumstances, use the following to determine HSG moves within the soil. This rate is controlled by the according to the texture of the new surface soil, soil profile. Approximate numerical ranges for provided that significant compaction has not occurred transmission rates shown in the HSG definitions (Brakensiek and Rawls 1983): were first published by Musgrave (USDA 1955). The four groups are defined by SCS soil scientists as HSG Soil textures follows: A Sand, loamy sand, or sandy loam Group A soils have low runoff potential and high B Silt loam or loam infiltration rate s even when thoroughly wetted. They C Sandy clay loam consist chiefly of deep, well to excessively drained D Clay loam, silty clay loam, sandy clay, silty sands or gravels and have a high rate of water clay, or clay transmission (greater than 0.30 in/hr). Group B soils have moderate infiltration rates when Drainage and group D soils thoroughly wetted and consist chiefly of moderately deep to deep, moderately well to well drained soils with moderately fine to moderately coarse textures. Some soils in the list are in group D because of a These soils have a moderate rate of water high water table that creates a drainage problem. transmission (0.15-0.30 in/hr). Once these soils are effectively drained, they are placed in a different group. For example, Ackerman Group C soils have low infiltration rates when soil is classified as A/D. This indicates that the thoroughly wetted and consist chiefly of soils with a drained Ackerman soil is in group A and the layer that impedes downward movement of water undrained soil is in group D. and soils with moderately fine to fine texture. These soils have a low rate of water transmission (0.05-0.15 in/hr). Group D soils have high runoff potential. They have very low infiltration rates when thoroughly wetted and consist chiefly of clay soils with a high swelling potential, soils with a permanent high water table, soils with a claypan or clay layer at or near the surface, and shallow soils over nearly impervious material. These soils have a very low rate of water transmission (0-0.05 in/hr). (210-VI-TR-55, Second Ed., June 1986) A-1 1992 TABLE 5-22 PERMISSIBLE VELOCITIES FOR UNLINED EARTHEN CHANNELS Permissible Velocity Soil Types (ft./sec.) Fine Sand (noncolloidal) 2.5 Sandy Loam (noncolloidal) 2.5 Silt Loam (noncolloidal) 3.0 Ordinary Firm Loam 3.5 Fine Gravel 5.0 Stiff Clay (very colloidal) 5.0 Graded, Loam to Cobbles (noncolloidal) 5.0 Graded, Silt to Cobbles (noncolloidal) 5.5 Alluvial Silts (noncolloidal) 3.5 Alluvial Silts (colloidal) 5.0 Coarse Gravel (noncolloidal) 6.0 Cobbles and Shingles 5.5 Shales and Hard Pans 6.0 Source: American Society of Civil Engineers V - 140 Custom Soil Resource Report Soil Map ..-: i., 1.. ..:,,, ... 701400 701500 ',MCC 701703 701800 76190C 702000 702100 702270 702300 702400 I I 1 38°11 90'N ..lir . .s '2 5C •••••, 90C ' ...._. __ , Ci 111111 2 8 6 'N.. . 45C\,..........______ . . 1 4..,r,"7••/(''' 1 ti. 6, —4.,•t..,,4 1...., '' iiii,4.p. --_-- . _ i. ill 1 . • ... •,-,c4";::,, ....4„. ' 44D, t•. 82ID, •, . • :•,i . • • -. . \ ,1• Iv••,,,,, ,.. -,-., . • \ ..... .1 . ., I ''', : .,..‘','• "c, li,t,', :e• . . . 4F . 'IV' \ .1 , „nit-- • i *qr.._ Aelkibt. 4E \ \ 1 , . . -. r. :, ,, ‘‘,,,, .. . -.. - ••,„ t.,.t, ,ti . , ,,.,, . 1. -,...itzi,I,No es . . . . ti. Oir-T" - 1.4•',1 . 1.-, •°- - er 1- 41,.. ., ;,k •A`'41k-11' .g4'.`t-+ a 4 t i , • • 90B ' • 1--3 •-- 'Ionise, . 4. ' • .. • ee.'' •-. 'al , :,r: "1\•'••'. ' •• -;• \ *• w. • ..• , •44.. ,`• .i, - 1 4.0. 4 A. 4 l`1 '7 1,, • ' - - ' , - ‘4 i:'4,,,,'" ° '(,,,•-,' 4' -*'• (4.14 °•(' . 4 ‘• ' • , 41/4 ,• ‘111,'lilt ' ,, i', fliliti•P• '41, , ''-^,-• Ni• Ili; • •0 , ' •..,7,t;:';'..'? •1' '( 4 -- . , .1* 0 N. 1, tIt . •4'91/4•Ns'ibt," -'t, — . t , . . •• ,p( !'i. , CC:3 CC:4C ' '71‘5,•••'4;40,1, "... ' , ,* , '•-• t•m ' 4 11‘r'' '' '%r - - •I • I ii C IF '' 'ii•'( I Cr ,i,,,,...,,, ,1().'t.v,tirvt.r,pp,r,,.., Ad ... ( . ' , I 38°11 18-N .. ' ''''1 • II 1 1 I 38.11 18.1,1 70140 701530 701803 701700 701800 701900 7020:0 70217 702330 702400 .?". .- In 0' Map Scale.1:4,950 if printed on A landscape(11"x 8.5')sheet Meters N 0 50 100 230 300 Feet A 0 Map prOjection"Web Men:ator4° Corner a:ordinates".WG584 5124'Ks L8MiZo2ae 17N 1016584 9 1 Custom Soil Resource Report Albemarle County, Virginia 4E—Ashe loam, 25 to 45 percent slopes ( D (6/J P0/Al T M ) Map Unit Setting National map unit symbol kbc2 Mean annual precipitation. 25 to 65 inches Mean annual air temperature. 54 to 59 degrees F Frost-free period: 195 to 231 days Farmland classification Not prime farmland Map Unit Composition Ashe and similar soils. 75 percent Estimates are based on observations, descriptions, and transects of the mapunrt. Description of Ashe Setting Landform: Mountain slopes Landform position (two-dimensional)• Summit Landform position (three-dimensional): lnterfluve Down-slope shape Convex Across-slope shape: Convex Parent material. Residuum weathered from granite and gneiss Typical profile H1 -O to 10 inches loam H2- 10 to 19 inches loam H3- 19 to 24 inches. sandy loam H4-24 to 79 inches bedrock Properties and qualities Slope. 25 to 45 percent Depth to restrictive feature. 20 to 40 inches to lithic bedrock Natural drainage class: Somewhat excessively drained Runoff class. Medium Capacity of the most limiting layer to transmit water(Ksat). Very low to high (0.00 to 5.95 in/hr) Depth to water table More than 80 inches Frequency of flooding None Frequency of ponding None Available water storage in profile Low(about 3.2 inches) Interpretive groups Land capability classification(irrigated) None specified Land capability classification(nonirrigated)• 7e Hydrologic Soil Group B Hydnc soil rating No 14 Custom Soil Resource Report 25B—Dyke silt loam, 2 to 7 percent slopes GrpP'P J5E5 i i L.L 517E 04 gEr Map Unit Setting ragBOTH PLANN�-D gr pQ5. National map unit symbol. kb8s Mean annual precipitation. 25 to 65 inches Mean annual air temperature 54 to 59 degrees F Frost-free period. 195 to 231 days Farmland classification All areas are prime farmland Map Unit Composition Dyke and similar soils: 85 percent Estimates are based on observations, descriptions, and transects of the mapunit Description of Dyke Setting Landform Fans Landform position (two-dimensional) Footslope Landform position (three-dimensional) Base slope Down-slope shape Concave Across-slope shape Convex Parent material Residuum weathered from greenstone Typical profile H9 -0 to 8 inches* silt loam H2-8 to 43 inches: clay H3-43 to 79 inches. gravelly clay Properties and qualities Slope' 2 to 7 percent Depth to restrictive feature More than 80 inches Natural drainage class Well drained Runoff class Medium Capacity of the most limiting layer to transmit water(Ksat) Moderately high to high (0 57 to 1 98 in/hr) Depth to water table: More than 80 inches Frequency of flooding None Frequency of ponding None Available water storage in profile. High (about 9.1 inches) Interpretive groups Land capability classification (irrigated) None specified Land capability classification(nonirrigated) 2e Hydrologic Soil Group: B Hydric soil rating. No 20 Appendix B VA DEQ STORMWATER DESIGN SPECIFICATION NO. 3 GRASS CHANNELS Longitudinal Slope. Grass channels are limited to longitudinal slopes of less than 4%. However, gg the limiting velocity requirements will typically require check dams to reduce the effective slope. Slopes steeper than 4% create rapid runoff velocities that can cause erosion and do not allow enough contact time for infiltration or filtering, unless check dams are used Longitudinal slopes of less than 2% are ideal and may eliminate the need for check dams However, channels designed with longitudinal slopes of less than 1% should be monitored carefully during construction to ensure a continuous grade, in order to avoid flat areas with pockets of standing water Soils. Grass channels can be used on sites with any type of soils. However, grass channels situated on Hydrologic Soil Group C and D soils will require compost amendments in order to improve performance, as noted in Table 3.1 (see Stormwater Design Specification No 4) Hydraulic Capacity. Grass channels are an on-line practice and must be designed with enough capacity to convey runoff from the 10-year design storm event within the channel banks and be non-erosive during both the 2-year and 10-year design storm events. This means that the much of the surface dimensions are dnven by the need to pass these larger storm events. Depth to Water Table. Designers should ensure that the bottom of the grass channel is at least 2 feet above the seasonally high water table to ensure groundwater does not intersect the filter bed, because this could lead to groundwater contamination or practice failure Utilities. Designers should consult local utility design guidance for the horizontal and vertical clearance between utilities and the channels Typically, utilities can cross grass channels if they are specially protected (e.g., double-casing) or are located below the channel invert Hotspot Land Uses. Grass channels are not recommended to treat stormwater hotspots, due to the potential for infiltration of hydrocarbons, trace metals and other toxic pollutants into groundwater. For a list of typical stormwater hotspots, see Stormwater Design Specification No 8 (Infiltration) Minimum Setbacks. Local ordinances and design criteria should be consulted to determine minimum setbacks from property lines, structures, utilities, and wells. As a general rule, grass channels should be set back at least 10 feet down-gradient from building foundations, 50 feet from septic system fields and 100 feet from private wells SECTION 6: DESIGN CRITERIA 6.1. Sizing of Grass Channels Unlike other stormwater practices, grass channels are designed based on a peak rate of flow. Designers must demonstrate channel conveyance and treatment capacity in accordance with the following guidelines: Version 1 8, April 13, 2010 Page 10 of 21 VA DEQ STORMWATER DESIGN SPECIFICATION NO. 3 GRASS CHANNELS • The longitudinal slope of the channel should ideally be between 1% and 2% in order to avoid scour and short-circuiting within the channel Longitudinal slopes up to 4% are acceptable; however, check dams will likely be required in order to meet the allowable maximum flow velocities • Hydraulic capacity should be verified using Manning's Equation or an accepted equivalent method, such as erodibility factors and vegetal retardance (NOVA 2007) o The Flow Depth for the peak treatment volume (1-inch rainfall) should be maintained at 3 inches or less. o Manning's "n" value for grass channels should be 0.2 for flow depths up to 4 inches, decreasing to 0.03 at a depth of 12 inches (which would apply to the 2-year and 10-year storms if an on-line application—NOVA, 2007; Haan et. al, 1994) o Peak Flow Rates for the 2-year and 10-year frequency storms must be non-erosive, in accordance with Table 3.3, or subject to a site-specific analysis of the channel lining material and vegetation; and the 10-year peak flow rate must be contained within the channel banks (with a minimum of 6 inches of freeboard) (NOTE: After the new Virginia Stormwater Management Regulation revisions take effect, the above requirement will be dnven by the SWM Regulations (4 VAC 50-60-66 A 1 and B 1), which will supersede the MS-19 cntena of the Virginia E&S Control Regulations.) • Calculations for peak flow depth and velocity should reflect any increase in flow along the length of the channel, as appropriate. If a single flow is used, the flow at the outlet should be used. • The hydraulic residence time (the time for runoff to travel the full length of the channel) should be a minimum of 9 minutes for the treatment volume (1-inch rainfall) design storm (Spyridakis, Mar, and Horner, 1982; Keblin, Walsh, Malma, and Charbeneau, 1998; Washington State Department of Ecology, 2005) If flow enters the swale at several locations, a 9 minute minimum hydraulic residence time should be demonstrated for each. entry point, using Equations 3.1 and 3.2 below(Equations 5-1 and 5-2,NOVA 2007). • The minimum length may be achieved with multiple swale segments connected by culverts with energy dissipaters The bottom width of the grass channel is therefore sized to maintain the appropriate flow geometry as follows: Equation 3.1: Manning's Equation Ft1,4-91,2ikril Where. V = flow velocity (ft./sec.) n = roughness coefficient(0.2, or as appropriate) D = flow depth (ft.) (NOTE: D approximates hydraulic radius for shallow flows) s = channel slope (ft./ft.) Version 1.8, April 13, 2010 Page 11 of 21 VA DEQ STORMWATER DESIGN SPECIFICATION NO. 3 GRASS CHANNELS Equation 3.2: Continuity Equation Q = V(WD) Where. Q= design Treatment Volume flow (cfs) V= design flow velocity(ft./sec.) W=channel width(ft) D=flow depth (ft.) (NOTE• channel width (W) x depth (D) approximates the cross sectional flow area for shallow flows.) Combining Equations 3.1 and 3 2, and re-writing them provides a solution for the minimum width: Equation 3.3:Minimum Width IV = (1441/ Solving Equation 3 2 for the corresponding velocity provides: Equation 3.4: Corresponding Velocity V= Q/ WD The resulting velocity should be less than 1 ft./sec The width, slope, or Manning's "n"value can be adjusted to provide an appropriate channel design for the site conditions. However, if a higher density of grass is used to increase the Manning's "n" value and decrease the resulting channel width, it is important to provide material specifications and construction oversight to ensure that the denser vegetation is actually established Equation 3 5 can then be used to ensure adequate hydraulic residence time. Equation 3.5: Grass Channel Length for Hydraulic Residence Time of 9 minutes (540 seconds) L = 540 V Where: L = minimum swale length(ft.) V= flow velocity (ft./sec.) Version 1.9, March 1, 2011 Page 12 of 21 VA DEQ STORMWATER DESIGN SPECIFICATION NO. 3 GRASS CHANNELS 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 23 Kentucky bluegrass Reed canarygrass > 10 3 2 3 Tall fescue Red fescue 0- 5 2 5 1 9 Sources Virginia E&S Control Handbook, 1992; Ree, 1949; Temple et al, 1987, NOVA, 2007 6.2. Geometry and Site Layout • Grass channels should generally be aligned adjacent to and the same length(minimum) as the contributmg drainage area identified for treatment • Grass channels should be designed with a trapezoidal or parabolic cross section A parabolic shape is preferred for aesthetic, maintenance and hydraulic reasons. • The bottom width of the channel should be between 4 to 8 feet wide. If a channel will be wider than 8 feet, the designer should incorporate benches, check dams, level spreaders or multi-level cross sections to prevent braiding and erosion along the channel bottom. • Grass channel side slopes should be no steeper than 4H:1 V for ease of mowing and routine maintenance Flatter slopes are encouraged, where adequate space is available, to aid in pre- treatment of sheet flows entering the channel Under no circumstances are side slopes to exceed 3H:1V. 6.3. Pretreatment Pretreatment is recommended for grass channels to dissipate energy, trap sediments and slow down the runoff velocity. The selection of a pre-treatment method depends on whether the channel will experience sheet flow or concentrated flow. Several reliable options are as follows: • Check dams (channel flow) The most common form of pre-treatment is the use of wooden or stone check dams (see Section 6 7) • Tree Check dams (channel flow): These are street tree mounds that are placed within the bottom of grass channels up to an elevation of 9 to 12 inches above the channel invert One side has a gravel or river stone bypass to allow runoff to percolate through (Cappiella et al, 2006). • Grass Filter Strip (sheet flow)• Grass filter strips extend from the edge of the pavement to the bottom of the grass channel at a slope of 5:1 or less. Alternatively, provide a combined 5 Version 1 9, March 1, 2011 Page 13 of 21 VA DEQ STORMWATER DESIGN SPECIFICATION NO. 3 GRASS CHANNELS feet of grass filter strip at a maximum 5% (20.1) cross slope and 3.1 or flatter side slopes on the grass channel • Gravel or Stone Diaphragm (sheet flow): The gravel diaphragm is located at the edge of the pavement or the edge of the roadway shoulder and extends the length of the channel to pre- treat lateral runoff This requires a 2 to 4 inch elevation drop from a hard-edged surface into a gravel or stone diaphragm. • Gravel or Stone Flow Spreaders (concentrated flow) The gravel flow spreader is located at curb cuts, downspouts, or other concentrated inflow points, and should have a 2 to 4 inch elevation drop from a hard-edged surface into a gravel or stone diaphragm The gravel should extend the entire width of the opening and create a level stone weir at the bottom or treatment elevation of the channel. 6.4. Check dams Check dams may be used for pre-treatment, to break up slopes, and to increase the hydraulic residence time in the channel. Design requirements for check dams are as follows • Check dams should be spaced based on the channel slope, as needed to increase residence time, provide Tv storage volume, or any additional volume attenuation requirements The ponded water at a downhill check dam should not touch the toe of the upstream checkdam • The maximum desired check dam height is 12 inches (for maintenance purposes) However, for challenging sites, a maximum of 18 inches can be allowed, with additional design elements to ensure the stability of the check dam and the adjacent and underlying soils The average ponding depth throughout the channel should be 12 inches. • Soil plugs serve to help minimize the potential for blow-out of the soil media underneath the check dams, due to hydrostatic pressure from the upstream ponding. Soil plugs are appropnate for Grass Channels (1) on slopes of 4% or greater, or (2) with check dams equal to or greater than 12-inches in height • Armoring may be needed at the downstream toe of the check dam to prevent erosion. • Check dams must be firmly anchored into the side-slopes to prevent outflanking; check dams must also be anchored into the channel bottom so as to prevent hydrostatic head from pushing out the underlying soils. • Check dams must be designed with a center weir sized to pass the channel design storm peak flow(10-year storm event for man-made channels) • The check dam should be designed so that it facilitates easy mowing. • Each check dam should have a weep hole or similar drainage feature so it can dewater after storms. • Check dams should be composed of wood, concrete, stone, or other non-erodible material, or be should configured with elevated driveway culverts • Individual channel segments formed by check dams or driveways should generally be at least 25 to 40 feet in length. 6.5. Compost Soil Amendments Soil compost amendments serve to increase the runoff reduction capability of a grass channel The following design criteria apply when compost amendments are used: Version 1 8, April 13, 2010 Page 14 of 21 Appendix C DEQ Virginia Runoff Reduction Method Re-Development Compliance Spreadsheet - Version 3.0 0 2011 BMP Standards and Specifications ®2013 Draft BMP Standards and Specifications Project Name Innisfree Village data cells CLEAR ALL Date. 3/28/2019 constant values Linear Development Project? No _ calculation cells Site Information _ I final results Post-Development Project (Treatment Volume and Loads) Enter Total Disturbed Area(acres) -) 3.04 ( Check: I I II BMP Design Specifications List. 2013 Draft Stds&Specs Maximum reduction required: 20% Linear project? No The site's net increase in impervious cover(acres)is: 0 Land cover areas entered correctly? ve Post-Development TP Load Reduction for Site fib/yr): 0.08 j Total disturbed area entered? 1,/ Pre-ReDevelopment Land Cover (acres) A Soils B Soils C Soils D Soils Totals Forest/Open Space(acres)-undisturbed 1.95 forest/open space 1.95 I Managed Turf(acres)--disturbed,graded for 0.43 yards or other turf to be mowed/managed 0.43 Impervious Cover(acres) 0.66 0.66 3.04 Post-Development Land Cover (acres) A Soils B Soils C Soils D Soils Totals Forest/Open Space(acres)-undisturbed, ? protected forest/open space or reforested land 1.32 1.32 Managed Turf(acres)-disturbed,graded for ' yards or other turf to be mowed/managed 1.36 1.36 Impervious Cover(acres) 0.36 0.36 Area Check OK. OK. OK. OK. 3.04 `Forest/Open Space areas must be protected in accordance with the Virginia Runoff Reduction Method Constants Runoff Coefficients(Rv) Annual Rainfall(inches) 43 A Soils B Soils C Soils D Soils Target Rainfall Event(Inches) 100 Forest/Open Space 0.02 0.03 0.04 0.05 Total Phosphorus(TP)EMC(mg/L) 0 26 Managed Turf 0 15 0 20 0.22 0.25 r Total Nitrogen(TN)EMC(mg/L) 1.86 Impervious Cover 0.95 0.95 0 95 0.95 Target TP Load(Ib/acre/yr) 0.41 Pj(unitless correction factor) 0.90 i LAND COVER SUMMARY-- PRE-REDEVELOPMENT LAND COVER SUMMARY--POST DEVELOPMENT Land Cover Summary-Pre t Land Cover Summary-Post(Final) Land Cover Summary-Post Land Cover Summ ary-Post 1 Pre-ReDevelopment listed Adjusted' Post ReDev &New Impervious Post-ReDevelopment Post-Development New Impervious Forest/Open Space I Forest/Open Space Forest/Open Space Cover(acres) 1.95 1.95 Cover(acres) 1.32 Cover(acres) 1.32 Weighted Rv(forest) 0.03 0.03 Weighted Rv(forest) 0.03 Weighted Rv(forest) 0.03 %Forest 64% 64% %Forest 43% %Forest 43% Managed Turf Cover(acres) 0.43 0.43 Managed Turf Cover 1.36 Managed Turf Cover 1.36 (acres) - I (acres) Weighted Rv(turf) 0.20 0.20 Weighted Rv(turf) 0.20 Weighted Rv(turf) 0.20 %Managed Turf 14% 14% %Managed Turf 45% %Managed Turf 45% • Impervious Cover(acres) 0 66 0.66 Impervious Cover(acres) 0.36 ReDev Impervious 0 36 New Impervious Cover 0.00 Cover(acres) (acres) Rv(impervious) 0.95 0.95 Rv(impervious) 0.95 Rv(impervious) 0.95 Rv(impervious) -- %Impervious 22% 22% %Impervious 12% %Impervious 12% Total Site Area(acres) 3.04 3.04 Final Site Area(acres) 3.04 Total ReDev Site Area 3.04 (acres) Site Rv 0.25 0.25 Final Post Dev Site Rv 0.22 ReDev Site Rv 0.22 • • •'': r . • r3da cKtt. _ Treatment Volume and Nutrient Load Treatment Volume and Nutrient Load Pre-ReDevelopment Treatment Volume Final Post-Development Post-ReDevelopment Post-Development 0 0643 0.0643 Treatment Volume 0.0545 Treatment Volume 0.0545 Treatment Volume(acre-ft) - (acre-ft) (acre-ft► ! (acre-ft) Final Post-Development Post-ReDevelopment Post-Development Pre-ReDevelopment Treatment Volume 2 g01 2,801 P (cubic feet) Treatment Volume 2,373 Treatment Volume 2,373 Treatment Volume(cubic - (cubic feet) (cubic feet) feet) Final Post- Post-ReDevelopment Pre-ReDevelopment TP Load Post-Development TP (Ib/yr) 1.76 1.76 Development TP Load 1.49 Load(TP) 1.49 Load(Ib/yr) (Ib/yr) (lb/yr)` Final Post-Development TP Post ReDevelopment TP TP load per acre 0.58 0.58 Load per acre 0.49 Load per acre Pre ReDevelopment 0.49 (b/acre/v) (Ib/acre/yrl (Ib/acre/yr) Baseline TP Load(Ib/yr) Max Reduction Required (0.41 lbs/acre/yr applied to pre redevelopment area excluding pervious 1.25 (Below Pre- 20% land proposed for new impervious cover) ReDevelopment Load) 'Adjusted Land Cover Summary TP Load Reduction Pre ReDevelopment land cover minus pervious land cover(forest/open space or Required for TP Load Reduction managed to acreage proposedfor new impervious cover 0.08 Required for New 0 9 turf) 9 p p P Redeveloped Area Impervious Area(Ib/yr) (Ib/yr) Adjusted total acreage is consistent with Post-ReDevelopment acreage(minus acreage of new impervious cover) Column I shows load reduction requriement for new impervious cover(based on new development load limit,0.41 lbs/acre/year). Post-Development Requirement for Site Area TP Load Reduction Required(Ib/yr) 0.08 Nitrogen Loads(Informational Purposes Only) Final Post-Development TN Load Pre-ReDevelopment TN Load(Ib/yr) 12 59 (Post-ReDevelopment&New Impervious) 10 66 (Ib/yr) I I I I Drainage Area A 1838_VRRM_ReDev_Compliance Spreadaheet_v3_082017 xlsm Drainage Area A Land Cover(acres) D.A A A Soils B Soils C Soils D Soils Totals Land Cover Rv Forest/Open Space(acres) 0.68 0.68 0.03 Managed Turf(acres) 0.31 0.31 0.20 Impervious Cover(acres) 0.07 0.07 0.95 Total Phosphorus Available for Remov Total 1 06 Post Development Treatment Vol, Stormwater Best Management Practices(RR=Runoff Reduction) Runoff Managed Impervious Volume from Runoff Remaining Total BMP Phosphorus Phosphorus Load Untreated Practice Reduction Turf Credit Cover Credit Upstream s Runoff Volume Treatment Removal from Upstream Phosphorus Load Credit(%) Area(acres) Area(acres) Practice(ft3) Reduction(ft) (ft') Volume(ft') Efficiency(%) Practices(Ib) to Practice(Ib) 1.Vegetated Roof(RR) 1.a Vegetated Roof#1(Spec#5) 45 •:+•.6 ••.•.••••••:•.ms., 0 0 0 0 •:•i•:•::•:•i•:•:•:•:••• 0.00 Pr••.:4•••ry - :••❖•:•:iiiP•:• •••••••••• 1.6.Vegetated Roof#2(Spec#5) 60 ♦••••••••• 0 0 0 0 0.00 .Rooftop Disconnection(RR) 2.a Simple Disconnection to A/B Soils ♦•••••••••+ 50 •O:i+Vi• ..•i+4 0 0 0 0 0 0.00 0.00 (Spec#1) ._•,:•:•:.+ 2.b.Simple Disconnection to C/D Soils i+i i i i•+•p i•Oi•Oi �••+25 •pp•+••••+ 0 0 0 0 0.00 0.00 (Spec#1) Astol• •.4.:Qi:+ 2.c.To Soil Amended Filter Path as r $$$$$•❖�+' Pe SO }•••••••••• �•i•O.O❖i•OP••• 0 0 0 0 0 0.00 0.00 specifications(existing C/D soils)(Spec#4) •tit•••••!•!•!•!•••!• 2.d To DryWell or French Drain#1, WO".�:•:❖:• 50 •*•�•�+��•�•�•�•••�• 0 0 0 0 25 0.00 0.00 Micro-Infilration#1(Spec#8) 0.49.•.e4es • 2.e.To Dry Well or French Drain#2, '•i❖::..a i• 90 :�% i%%i•i+ii 0 0 0 0 25 0.00 0.00 Micro-Infiltration#2(Spec#8) ••,••••••••••�••• 2.f To Rain Garden#1, •�.:•.;•:;....:�.i. 40 ••••••• 0 0 0 0 25 0.00 0.00 Micro-8ioretentbn#1(Spec#9) �•�•�••�;•;.;•i;�• 2.g.To Rain Garden#2, 4b4•:.•i.ti0•i 80 •i••••.•�•.•i••O 0 0 0 0 50 0.00 0.00 Micro-Bioretention#2(Spec#9) •••:••�•� .i•%%i J%i•i Oi+ - 2.h To Rainwater Harvesting(Spec#6) 0 •:•:.•.:•••+ 0 0 0 0 0 0.00 0.00 2.1 To Stormwater Planter, ••••••••••••••••+ 40 ?••++i•❖�•i••�•�+ 0 0 0 0 25 0.00 0.00 _ Urban Bioretention(Spec#9,Appendix A) ••+•'••••s.••+ .Permeable Pavement (RR) 3.a Permeable Pavement#1(Spec#7) 45 ..:e:..��•i:�����1 0 0 0 0 25 0.00 0.00 'rih•2❖•••OOD �••��•+�D4'N' ••••••••D.• ••.•••••••• ♦•••••••••• •��••••••••♦ •4.••••��••• 3.b.Permeable Pavement#2(Spec#7) 75 ••i00.OPihO❖: •p p.*:.:.•••• 0 0 0 25 ••••••:••❖•••••••••: 0.00 .Grass Channel(RR) 4.a Grass Channel A/B Soils(Spec#3) 20 0.31 0.07 0 95 379 473 15 0.00 0.30 4.b Grass Channel C/D Soils(Spec#3) 10 0 0 0 15 0.00 0.00 0 4.c Grass Channel with Compost Amended Soils as per specs(see Spec#4) 20 0 0 0 0 15 0.00 0.00 .Dry Swale(RR) 5.a Dry Swale#1(Spec#10) 40 0 0 0 0 20 0.00 0.00 5.b.Dry Swale#2(Spec#10) 60 0 0 0 0 40 0.00 0.00 _.Bioretention(RR) •.a Bioretention#1 or Micro-Bioretention#1 or 40 0 0 0 0 25 0.00 0.00 Urban Bioretention(Spec#9) 6.b.Bioretention#2 or Micro-Bioretention#2 80 0 0 0 0 SO 0.00 0.00 (Spec#9) .Infiltration(RR) 7 a Infiltration#1(Spec#8) 50 0 0 0 0 25 0.00 0.00 7 b.Infiltration#2(Spec#8) 90 0 0 0 0 25 0.00 0.00 .Extended Detention Pond(RR) 8.a ED#1(Spec#15) 0 0 0 0 0 15 0.00 0.00 • 8.b.ED#2(Spec#15) 15 0 0 0 0 15 0.00 0.00 Sheetflow to filter/Open Space(RR) 3.a Sheetflow to Conservation Area,A/B Soils 75 0 0 0 0 0 0.00 0.00 (Spec#2) 3.b.Sheetflow to Conservation Area,C/D Soils 50 0 0 0 0 0 0.00 0.00 (Spec#2) c Sheetflow to Vegetated Filter Strip,A Soils or Compost Amended B/C/D Soils 50 0 0 0 0 0 0.00 0.00 (Spec#2) 1 or 4 I 1 312372019 TOTAL IMPERVIOUS COVER TREATED(ac) 0 07 AREA CHECK OK. 11 33 AM TOTAL MANAGED TURF AREA TREATED(ac) 0.31 AREA CHECK OK. 1838_VRR M_ReDev_Compliance_Spreadeheet_v3_082017.xiem D.A.-A TOTAL RUNOFF REDUCTION IN D A A(ft') 95 TOTAL PHOSPHORUS AVAILABLE FOR REMOVAL IN D A A(Ib/yr) 0.30 TOTAL PHOSPHORUS REMOVED WITH RUNOFF REDUCTION PRACTICES IN 0 A A(Ib/yr) 0.10 TOTAL PHOSPHORUS REMAINING AFTER APPLYING RUNOFF REDUCTION PRACTICES IN D A.A(Ib/yr) 0.20 SEE WATER QUALITY COMPLIANCE TAB FOR SITE COMPLIANCE CALCULATIONS 0.Wet Swale(no RR) 10.a Wet Swale#1(Spec#11) 0 0 0 0 0 20 0.00 0.00 10.b Wet Swale#2(Spec#11) 0 0 0 0 0 40 0.00 0.00 1. Filtering Practices(no RR) 11.a.Filtering Practice#1(Spec#12) 0 0 0 0 0 60 0.00 0.00 11.b.Filtering Practice#2(Spec#12) 0 0 0 0 0 65 0.00 0.00 2.Constructed Wetland(no RR) 12.a.Constructed Wetland#1(Spec#13) 0 0 0 0 0 50 0.00 0.00 12.b Constructed Wetland#2(Spec#13) 0 0 0 0 0 75 0.00 0.00 S.Wet Ponds(no RR) 13.a Wet Pond#1(Spec#14) 0 0 0 0 0 50 0.00 0.00 13.b Wet Pond#1(Coastal Plain)(Spec#14) 0 0 0 0 0 45 0.00 0.00 13.c Wet Pond#2(Spec#14) 0 0 0 0 0 75 0.00 0.00 13.d Wet Pond#2(Coastal Plain)(Spec#14) 0 0 0 0 0 65 0.00 0.00 -',Manufactured Treatment Devices(no RR) 14.a Manufactured Treatment Device- 0 0 0 0 0 20 0.00 0.00 Hydrodynamic .4.b Manufactured Treatment Device-Filtering 0 0 0 0 0 20 0.00 0.00 L4.c Manufactured Treatment Device-Generic 0 0 0 0 0 20 0.00 0.00 TOTAL IMPERVIOUS COVER TREATED(ac) 0.07 AREA CHECK OK. TOTAL MANAGED TURF AREA TREATED(ac) 0.31 AREA CHECK OK TOTAL PHOSPHORUS REMOVAL REQUIRED ON SITE(Ib/yr)I 0.08 TOTAL PHOSPHORUS AVAILABLE FOR REMOVAL IN D.A.A(Ib/yr) 0.30 TOTAL PHOSPHORUS REMOVED WITHOUT RUNOFF REDUCTION PRACTICES IN D.A.A(Ib/yr) 0.00 TOTAL PHOSPHORUS REMOVED WITH RUNOFF REDUCTION PRACTICES IN D A.A(Ib/yr) 0.10 TOTAL PHOSPHORUS LOAD REDUCTION ACHIEVED IN D A A(Ib/yr) 0.10 TOTAL PHOSPHORUS REMAINING AFTER APPLYING BMP LOAD REDUCTIONS IN D.A A(Ib/yr) 0.20 SEE WATER QUALITY COMPLIANCE TAB FOR SITE COMPLIANCE CALCULATIONS NITROGEN REMOVED WITH RUNOFF REDUCTION PRACTICES IN D A A(Ib/yr) 0.77 NITROGEN REMOVED WITHOUT RUNOFF REDUCTION PRACTICES IN D A A(Ib/yr) 0.00 TOTAL NITROGEN REMOVED IN D A A(lb/yr) 0.77 3/282019 2 of 4 1133 AM 1838_VRRM ReDev_Compsance_Spreadsheet_y3_082017.dem D.A A -1 in D.A.A(Ib/yr) 0.30 me in D.A.A(ft3) 473 --Select from dropdown lists- Phosphorus Remaining Downstream Practice to be Nitrogen Nitrogen Load Untreated Nitrogen Remaining Removed By Phosphorus Load Employed Removal from Upstream Nitrogen Load to Removed By Nitrogen Load Practice(lb) (lb) Efficiency(%) Practices(Ibs) Practice(Ibs) Practice(Ibs) (Ibs) 1.Vegetated Roof(FIR) i:i.N.N.A.V..N.W.. 0.00 0.00 0 ❖�•:•:��•::•:•:�:; 0.00 0.00 0.00 0.00 0.00 ::••;•, 0 ••• . 0.00 0.00 0.00 - 11.11.1111 2.Rooftop Disconnection(RR) 0.00 0.00 0 0.00 0.00 0.00 0.00 0.00 0.00 0 0.00 0.00 0.00 0.00 0.00 0.00 0 0.00 0.00 0.00 0.00 0.00 0.00 15 0.00 0.00 0.00 0.00 0.00 0.00 15 0.00 0.00 0.00 0.00 0.00 0.00 40 0.00 0.00 0.00 0.00 0.00 0.00 60 0.00 0.00 0.00 0.00 0.00 0.00 0 0.00 0.00 0.00 0.00 0.00 0.00 40 0.00 0.00 0.00 0.00 3.Permeable Pavement (RR) 0.00 0.00 25 0.00 0.00 0.00 0.00 'D'i•P•.'iii.�• 4h.....•••.•.•:.0.00 0.00 25 .=...t.:•:•:•:•:•:••.:•:.: 0.00 0.00 0.00 4.Grass Channel(RR) 0.10 0.20 20 0.00 2.13 0.77 1.36 0.00 0.00 20 0.00 0.00 0.00 0.00 0.00 0.00 20 0.00 0.00 0.00 0.00 S.Dry Swale(RR) 0.00 0.00 25 0.00 0.00 0.00 0.00 0.00 0.00 35 0.00 0.00 0.00 0.00 6.Rioretention(RR) 0.00 0.00 40 0.00 0.00 0.00 0.00 0.00 0.00 60 0.00 0.00 0.00 0.00 7.Infiltration(RR) 0.00 0.00 15 0.00 0.00 0.00 0.00 0.00 0.00 15 0.00 0.00 0.00 0.00 8.Extended Detention Pond(RR) 0.00 0.00 10 0.00 0.00 0.00 0.00 0.00 0.00 10 0.00 0.00 0.00 0.00 9.Sheetflow to Filter/Open Space(RR) 0.00 0.00 0 0.00 0.00 0.00 0.00 0.00 0.00 0 0.00 0.00 0,00 0.00 0.00 0.00 0 0.00 0.00 0.00 0.00 3 of 4 3/28/2019 11:33 AM 1838_VRRM ReDev_Compliance_Speadsheet_v3_082017.dam D.A.A TOTAL RUNOFF REDUCTION IN D A.A(f1) 95 NITROGEN REMOVED WITH RUNOFF REDUCTION PRACTICES IN D.A.A(Ib/yr) 0.77 SEE WATER QUALITY COMPLIANCE TAB FOR SITE CALCULATIONS(Information Only) I 10.Wet Swale(Coastal Plain)(no RR) 0.00 0.00 25 0.00 0.00 0.00 0.00 0.00 0.00 35 0.00 0.00 0.00 0.00 11. Filtering Practices(no RR) 0.00 0.00 30 0.00 0.00 0.00 0.00 0.00 0.00 45 0.00 0.00 0.00 0.00 12.Constructed Wetland(no RR) 0.00 0.00 25 0.00 0.00 0.00 0.00 0.00 0.00 55 0.00 0.00 0.00 0.00 13.Wet Ponds(no RR) 0.00 0.00 30 0.00 0.00 0.00 0.00 0.00 0.00 20 0.00 0.00 0.00 0.00 0.00 0.00 40 0.00 0.00 0.00 0.00 0.00 0.00 30 0.00 0.00 0.00 0.00 0.00 0.00 0 0.00 0.00 0.00 0.00 0.00 0.00 0 0.00 0.00 0.00 0.00 0.00 0.00 0 0.00 0.00 0.00 0.00 4 of 4 3/28/2019 11:33 AM 1838_VRRM_ReDev_Compiance Spieadsheet_v3_002017.dsm DAB Drainage Area B Drainage Area A Land Cover(acres) A Soils B Soils C Soils D Soils Totals Land Cover Rv Forest/Open Space(acres) 0.07 0.07 0.03 Managed Turf(acres) 0.09 0.09 0.20 Impervious Cover(acres) 0.02 0.02 0.95 Total Phosphorus Available for Removal Ir Total 0.18 Pout Development Treatment Volume Stormwater Best Management Practices(RR=Runoff Reduction) Runoff Managed Turf Impervious Volume front Runoff Remaining Total BMP Phosphorus Phosphorus Untreated Practice Reduction Credit Area Cover Credit Upstream Reduction Runoff Treatment Removal Load from Phosphorus Upstream Load to Credit 06) (acres) Area(acres) Practice(ft) (fe) Volume(fe) Volume(ft) Efficiency(%) Practices(lb) Practice lib) 1.Vegetated Roof(RR) lea Vegetated Roof#1(Spec#5 45 ••••••••••••• •.'•'.• •'•.•:.• 0 0 0 0 Veti' e•••••• 0.00 egIP I •.•••••.• ;.O•••••• 0.00 i.b Vegetated Roof#2(Spec#5) 60 • ••••••••• "�'•••'••••••• 0 0 0 0 �•�.4•ii'i•Ti•. ♦•••••••♦ .•.e.v.•.w.•. ••:•Dole): 2.Rooftop Disconnection(RR) 2.a.Simple Disconnection to A/B Soils i is i i i•4•i i SO O i•O�:•J•:•: 0 0 0 0 0 0.00 0.00 (Spec#1) 4..6M+Mat••_et• 2.b.Simple Disconnection to C/D Soils )•••.•••�i:••Oi #1 25 •Je•O••O•• 0 0 0 0 0 0.00 0.00 (Spec I 0:•ei'dA•J•• 2.c.To Soil Amended Filter Path as per :•••••••• specifications(existing C/D soils)(Spec#4) 50 •%Vets;•;•;•;•;. 0 0 0 0 0 o.Do o.Do s••r••-S•••=••• 2.d To Dry Wdlor French Drain el, ••;•;�•O;9;4�P 50 •••••••••• 0 0 0 0 25 0.00 0.00 Micro-lnfilration ill(Spec#8) ••••••••• 2.e.To Dry Well or French Drain 112, •�•••••••••••e���•� 90 ••••••••♦ 0 0 0 0 25 0.00 0.00 Micro-Infiltration#2(Spec#8) .0*•• **: 2.f.To Rain Garden#1, •�»1•'��•� �••:•••�� 0 0 0 0 25 0.00 0.00 Micro-Bioretention#1(Spec 09) 40 .%•.A%i%.i 2.g.To Rain Garden#2, 4•i•J4•i 4 i•i 4•4 •0•JPiO•P•0O 0 0 0 0 50 0.00 0.00 Micro-Bioretention#2(Spec#9) ••••+!•••!••••4 ❖40. 2.h To Rainwater Harvesting(Spec#6) 0 4••••e4•••••.:44. 0 0 0 0 0 0.00 0.00 2.i.To Stormwater Planter •ie ese••c••••e •�••�•••• 0 0 0 0 25 0.00 0,00 Urban Bioretention(Spec#9,Appendix40 .••4••••�••••••••• I P A) ♦•••••••• 3.Permeable Pavement (RR) y4.N.4 i:•i• 3.a Permeable Pavement#1 ••••••••••(Spec#71 65 �i i•OSO:444 0 0 0 0 25 0.00 0.00 3.b Permeable Pavement#2(Spec#7) KAiiOi•O 75 %•e•.•••••• ••_.•......... 0 0 0 25 .....• ••Wt. e% 0.00 4.Grove Channel(RR) 4.a Grass Channel A/B Soils(Spec#3) 20 0.09 0.02 0 29 116 145 15 0.00 0.09 4.b Grass Channel C/D Soils(Spec#3) 10 0 0 0 0 15 0.00 0.00 4.c Grass Channel with Compost Amended Soils as per specs(see Spec#4) 20 0 0 0 0 15 0.00 0.00 5.Dry Swale(RR) 5.a Dry Swale#1(Spec#10) 40 0 0 0 0 20 0.00 0.00 5.b Dry Swale#2(Spec#10) 60 0 0 0 0 40 0.00 0.00 6.8loretention(RR) 6.a.Bioretention#1 or Micro-Bioretention#1 or 40 0 0 0 0 25 0.00 0.00 Urban Bioretention(Spec#9) 6.b Bioretention#2 or Micro-Bioretention#2 80 0 0 0 0 50 0.00 0.00 (Spec#9) 7.Infiltration(RR) 7 a Infiltration#1(Spec#8) 50 0 0 0 0 25 0.00 0.00 7 b Infiltration#2(Spec#8) 90 0 0 25 0.00 0.00 0 0 8.latended Detention Pond(RR) 8.a ED#3(Spec#15) 0 0 0 0 0 15 0.00 0.00 8.b.EO#2(Spec#15) 15 0 0 0 0 15 0.00 0.00 9.Sheetflow to Filter/Open Space(RR) 9.a Sheetflow to Conservation Area,A/B Soils 75 0 0 0 0 0 0.00 0.00 (Spec#2) 1 of 4 3282019 11.33 AM 1038_VRRM ReDev_ComWanca_Spreadaheet_v3 082017.40m DAB 9.b.Sheetfow to Conservation Area,C/D Soils 50 0 0 0 0 0 0.00 0.00 (spec#2) 9.c.Sheetflow to Vegetated Filter Strip,A Soils or Compost Amended B/C/D Soils 50 0 0 0 0 0 0.00 0.00 (Spec#2) TOTAL IMPERVIOUS COVER TREATED(ac) 0.02 AREA CHECK.OK. TOTAL TURF AREA TREATED(ac) 0.09 AREA CHECK OK. TOTAL RUNOFF REDUCTION IN D A 8 lit') 29 TOTAL PHOSPHORUS AVAILABLE FOR REMOVAL IN D.A.B(lb/yr) 0.09 TOTAL PHOSPHORUS REMOVED WITH RUNOFF REDUCTION PRACTICES IN O.A.B(lb/yr) 0.03 TOTAL PHOSPHORUS REMAINING AFTER APPLYING RUNOFF REDUCTION PRACTICES IN D.A.8(Ib/yr) 0.06 SEE WATER QUALITY COMPLIANCE TAB FOR SITE COMPLIANCE CALCULATIONS 10.Wet Swale(no RR) 10.a.Wet Swale#1(Spec#11) 0 0 0 0 0 20 0.00 0.00 10.b Wet Swale#2(Spec#11) 0 0 0 0 0 40 0.00 0.00 11. Filtering Practices(no RR) 11.a.Filtenng Practice#1(Spec#12) 0 0 0 0 0 60 0.00 0.00 118.Fihenng Practice#2(Spec#12) 0 0 0 0 0 65 0.00 0.00 12.Constructed Wetland(no RR) 12.a.Constructed Wetland#1(Spec#13) 0 0 0 0 0 SO 0.00 0.00 12.6.Constructed Wetland#2(Spec#13) 0 0 0 0 0 75 0.00 0.00 13.Wet Ponds(nu RR) 13.a.Wet Pond#1(Spec#14) 0 0 0 0 0 50 0.00 0.00 13.b Wet Pond#1(Coastal Plain)(Spec#14) 0 0 0 0 0 45 0.00 0.00 13.c.Wet Pond#2(Spec#14) 0 0 0 0 0 75 0.00 0.00 13.d.Wet Pond#2(Coastal Plain)(Spec#14) 0 0 0 0 0 65 0.00 0.00 14.Manufactured Ireatment Devices(no RR) 14.a.Manufactured Treatment Device- 0 0 0 0 0 20 0.00 0.00 Hydrodynamic 14.b Manufactured Treatment Device-Filtering 0 0 0 0 0 20 0.00 0.00 14.c Manufactured Treatment Device-Generic 0 0 0 0 0 20 0.00 0.00 TOTAL IMPERVIOUS COVER TREATED(ac) 0.02 AREA CHECK.OK. TOTAL MANAGED TURF AREA TREATED(ac) 0.09 AREA CHECK OK. TOTAL PHOSPHORUS REMOVAL REQUIRED ON SITE(Ib/yr)l_ 0.08 i TOTAL PHOSPHORUS AVAILABLE FOR REMOVAL IN D A.B(lb/yr) 0.09 TOTAL PHOSPHORUS REMOVED WITHOUT RUNOFF REDUCTION PRACTICES IN D.A.8(Ib/yr) 0.00 TOTAL PHOSPHORUS REMOVED WITH RUNOFF REDUCTION PRACTICES IN O.A.8(Ib/yr) 0.03 TOTAL PHOSPHORUS LOAD REDUCTION ACHIEVED IN 0 A.B(Ib/yr) 0.03 TOTAL PHOSPHORUS REMAINING AFTER APPLYING BMP LOAD REDUCTIONS IN O.A.B(lb/yr) 0.06 SEE WATER QUALITY COMPLIANCE TAB FOR SITE COMPLIANCE CALCULATIONS NITROGEN REMOVED WITH RUNOFF REDUCTION PRACTICES IN D A.B(Ib/yr) 0.23 NITROGEN REMOVED WITHOUT RUNOFF REDUCTION PRACTICES IN D.A.B(Ib/yr) 0.00 TOTAL NITROGEN REMOVED IN D.A.8(lb/yr) 0.23 2 of 4 3f282019 1133AM 1838 VRRM_ReDev_Comgiance Spreadsheet v3_08201745n1 DAB I D.A.B(Ib/yr) 0.09 tInD.A.B(ft3) 145 --Select from dropdown lists-- Phosphorus Remaining Nitrogen Nitrogen Load Untreated Nitrogen Remaining Removed ByDownstream Practice to be Phosphorus Employed Removal from Upstream Nitrogen Load to Removed fly Nitrogen Practice(Ib) Load(Ib) Efficiency(%) Practices(Ibs) Practice(Ibs) Practice(Ibs) Load(Ibs) 1.Vegetated Roof(RR) 0.00 000 0 :+:•::i'i O:•:S 0.00 000 0.00 '•ti eoti6DJ•'P••• 0.00 0.00 0 ::i i4•i• •fiVi•:•:a i 0.00 0.00 0.00 2.Rooftop Disconnection(RR) 0.00 0.00 0 0.00 0.00 0.00 0.00 0.00 0.00 0 0,00 0.00 0.00 0.00 0.00 0.00 0 0.00 0.00 0.00 0.00 i 0.00 0.00 15 0.00 0.00 0.00 0.00 0.00 0.00 15 0.00 0.00 0.00 0.00 0.00 0.00 40 0.00 0.00 0.00 0.00 0.00 0.00 60 0.00 0.00 0,00 0.00 0.00 0.00 0 0.00 0.00 0.00 0.00 0.00 0.00 40 0.00 0.00 0.00 0.00 3.Permeable Pavement(RR) 0.00 0.00 25 0 00 0.00 0.00 0.00 yvvrvr.;i5VA r 0.00 0.00 25 •••••••••••• 0.00 0.00 0.00 0.03 0.06 20 0.00 0.65 0.23 0.42 0.00 0.00 20 0.00 0.00 0.00 0.00 0.00 0.00 20 0.00 0.00 0.00 0.00 5.Dry Swale(RR) 0.00 0.00 25 0.00 0.00 0.00 0.00 0.00 0.00 35 000 0.00 0.00 0.00 6.Bioretention(RR) 0.00 0.00 40 0.00 0.00 0.00 0.00 0.00 0.00 60 0.00 0.00 0.00 0.00 7.Infiltration(RR) 0.00 0.00 15 0.00 0.00 0.00 0.00 0.00 0.00 15 0.00 0.00 0.00 0.00 8.Extended Detention Pond(RR) 0.00 0.00 10 0.00 0.00 0.00 0.00 0.00 0.00 10 0.00 0.00 0.00 0.00 9.Sheetflow to Filter/Open Space(RR) 0.00 0.00 0 0.00 0.00 0.00 0.00 3 of 4 3282015 11'33 AM 1838_VRRM ReDev_Compliance_Spreadsheet_v3_082017 Own D.A.B 0.00 0.00 0 0.00 0.00 0.00 0.00 0.00 0.00 0 0.00 0.00 0.00 0.00 TOTAL RUNOFF REDUCTION IN D.A.B(ft') 29 NITROGEN REMOVED WITH RUNOFF REDUCTION PRACTICES IN D.A B(Ib/yr) 0.23 SEE WATER QUALITY COMPLIANCE TAB FOR SITE CALCULATIONS(Information Only) 10.Wet Swale(Coastal Plain)(no RR) 0.00 0.00 25 0.00 0.00 0.00 0.00 0.00 0.00 35 0.00 0.00 0.00 0.00 11. Filtering Practices(no RR) 0.00 0.00 30 0.00 0.00 0.00 0.00 0.00 0.00 45 0.00 0.00 0.00 0.00 12.Constructed Wetland(no RR) 0.00 0.00 25 0.00 0.00 0.00 0.00 0.00 0.00 55 0.00 0.00 0.00 0.00 1111111.1111111 13.Wet Ponds(no RR) 0.00 0.00 30 0.00 0.00 0.00 0.00 0.00 0.00 20 0.00 0.00 0.00 0.00 0.00 0.00 40 0.00 0.00 0.00 0.00 0.00 0.00 30 0.00 0.00 0.00 0.00 14.Manufactured BMP(no RR) 0.00 0.00 0 0.00 0.00 0.00 0.00 • 0.00 0.00 0 0.00 0.00 0.00 0.00 0.00 0,00 0 0.00 0.00 0.00 0.00 4 of4 3282019 11:33 AM 1838_VRRY R.Dev_Compliance_Spreadsheet_v3_082017.xlem D.A.C Drainage Area C CLEAR BMP AREAS Drainage Area A Land Cover(acres) A Soils B Soils C Soils D Soils Totals Land Cover Rv Forest/Open Space(acres) 0.10 0.10 0,03 ' Managed Turf(acres) 0.16 0.16 0.20 Impervious Cover(acres) 0.02 0.02 0.95 Total Phosphorus Available for Removal it Total 0.28 Post Development Treatment Volumr Stormwater Best Management Practices(RR=Runoff Reduction) Runoff Managed impervious Volume from Runoff Remaining Total BMP Phosphorus Phosphorus Untreated Practice Reduction Turf Credit Cover Credit Upstream Reduction Runoff Treatment Removal Load from Phosphorus Credit(%) Area(acres) Area(acres) Practice(fa) (fts) Volume(ft3) Volume(ft') Efficiency(%) Upstream Lo to Practices(Ib) Practicead to 1.Vegetated Roof(RR) 1.a.V Vegetated Roof ••••••••• 0 0 0 0 •••Ab 4.O 0•� ea I p ) 45 OPOa 4.0.40 iS........PPP *VOW.' •. •t1.....••••••PPP Lb.Vegetated Roof#2(Spec 45) 60 ••PPP•••0•�4 ♦•PPPP 0 •••••••%!•••i••••0 0 0 �.4.A..4444 O0.••0•.•i•P• .•i•i•r4•i•••.4• 0.00 7.Roof top Disconnection 1RR) 2.a.Simple Disconnection to A/B Soils ;'•'.••;:'.•i i; (Spec#1) •so .���4 "i i 0 0 0 0 0 0.00 0.00 2.b Simple Disconnection to C/D Sills 25 44 i 44 i• (Spec 41 •0.4•••P.•.':•j 0 0 0 0 0 0.00 0.00 2.c.To Soil Amended Filter Path as per ••4•••i••❖ii •�❖44444 0 0 0 0 0 0,00 0.00 specifications(misting C/D soils)Spec#4) 50 •.•f•.•!•.•••.•.•• 2.d To Dry Well or French Drain#1, i.:4:4••.4••• 50 •4Q••Q••• 0 0 0 0 25 0.00 0.00 Micro-Infilration#1(Spec 48) .�•ill••••••• 2.e.To Dry Well or French Drain#2, �:74:4.*°i 90 •..•..•.. 0 0 0 0 25 0,00 0.00 Micro-lnfihradon#2(Spec#8) 4.te,,•,•:•:•.1• 2.f To Rain Garden#1, •••iiii•i• Micro-Bioretention ill S .•�•0••i•0i44 0 0 0 0 25 0.00 0.00 (pec#91 •titiyl•.V 2.g.To Rain Garden#2, i••.•Pei.:.• 80 :Wei.) 0 0 0 0 50 0.00 0.00 Mlcro-Bloreteotton#2(Spec 49) ♦��6••••• PPPPtiiSo """••• 0 0 0 0 0 0.00 0.00 2.h To Rainwater Harvesting(Spec#6) 0 �••.����•����•�• •4•• :44 2.I.To Stormwater Planter, v�4v ••• Urban Bioretention(Spec#9,Appendix A) i 40 000........e.o•• 0 0 0 0 0 25 0.00 0.00 3.Permeable Pavement(RR) 3.a.Permeable Pavement#1(Spec N7 45 •••••••••••••••••' 0 0 0 0 25 0.00 0.00 3.h Permeable pavement X2(Spec#7) 75 ♦•.•••4 . ••••••.•.•••s 0 0 0 25 0.i•it.���•�.•••••.! 0.00 4.Grass Channel(RR) 4.a.Grass Channel A/B Soils(Spec e3) 20 0.16 0.02 0 39 156 195 15 0.00 0.12 4.b Grass Channel C/D Soils(Spec#3) 10 0 0 0 0 15 0.00 0.00 4.c.Grass Channel with Compost Amended Soils as per specs(see Spec#4) 20 0 0 0 0 15 0.00 0,00 S.Dry Swale(RR) 5.a.Dry Swale#1(Spec#10) 40 0 0 0 0 20 0.00 0.00 S.b Dry Swale N2(Spec#101 60 0 0 0 0 40 0.00 0.00 6.aloretentiorl(RR) 6.a Bioretention#1 or Micro-Bioretention#1 or 40 0 0 0 0 25 0.00 0.00 Urban Bioretention(Spec#9) 6.b Bioretentlon#2 or Micro-Bioretentlon#2 80 0 0 0 0 50 0.00 0.00 (Spec#9) 7.Infiltration(RR) 7.a.Infiltration#1(Spec#8) 50 0 0 0 0 25 0.00 0.00 7 b Infiltration#2(Spec#8) 90 0 0 0 0 25 0.00 0.00 8.Eltended Detention Pond(RR) 8.a.ED#1(Spec#15) 0 0 0 0 0 15 000 0.00 8.b ED#2(Spec#15) 15 0 0 0 0 15 0.00 0.00 9.Shcetflow to Filter/Open Space(RN) 9.a.Sheetfiow to Conservation Area,A/B Soils 75 (Spec#1) 0 0 0 0 0 0.00 0.00 9.b.Sheetfiow to Conservation Area,CID Sills 50 0 0 0 0 0 0.00 0.00 (Spec#2) 1 of 4 3r2B2019 11:33 AM 1838_VRRM_ReDev_Compsance_Spraadahaot v3 082017.Atm SAC 9.c.Sheetfow to Vegetated Fitter Strip,A Soils or Compost Amended 8/C/D Soils 50 0 0 0 0 0 0.00 0.00 (Spec#2) TOTAL IMPERVIOUS COVER TREATED lac) 0.02 AREA CHECK OK. TOTAL MANAGED TURF AREA TREATED lac) 0.16 AREA CHECK OK TOTAL RUNOFF REDUCTION IN D A.C(fel 39 TOTAL PHOSPHORUS AVAILABLE FOR REMOVAL IN D.A.C(lb/yr) 0 12 TOTAL PHOSPHORUS REMOVED WITH RUNOFF REDUCTION PRACTICES IN D.A.C(Ib/yr) 0.04 TOTAL PHOSPHORUS REMAINING AFTER APPLYING RUNOFF REDUCTION PRACTICES IN D.A.C(Ib/yr) 0.08 SEE WATER QUALITY COMPLIANCE TAB FOR SITE COMPLIANCE CALCULATIONS 10.Wet Swale(no RR) 10.a Wet Swale e1(Spec#11) 0 0 0 0 0 20 0.00 0.00 10.6 Wet Swale g2(Spec all) 0 0 0 0 0 40 0.00 0.00 11. I illering Practices(no RR) , 11.a.Filtering Practice e1(Spec N12) 0 0 0 0 0 60 0.00 0.00 11.b Filtering Practice#2(Spec g12) 0 0 0 0 0 65 0.00 0.00 12.Constructed Wetland(no RR) 12.a.Constructed Wetland#1(Spec a13) 0 0 0 0 0 50 0.00 0.00 12.b Constructed Wetland a2(Spec N13) 0 0 0 0 0 75 0.00 0.00 13.Wet Ponds(no RRI 13.a.Wet Pond#1(Spec#14) 0 0 0 0 0 50 0.00 0.00 13.b Wet Pond#1(Coastal Plain)(Spec#14) 0 0 0 0 0 45 0.00 0.00 13.c.Wet Pond g2(Spec 614) 0 0 0 0 0 75 0.00 0.00 13.d Wet Pond#2(Coastal Plain)(Spec#14) 0 0 0 0 0 65 0.00 0.00 14.Manufactured Treatment Devices!no OR) 14.a.Manufactured Treatment Device- 0 0 0 0 0 20 0.00 0.00 Hydrodynamic 14.b Manufactured Treatment Device-Filtering 0 0 0 0 0 20 0.00 0.00 14.c.Manufactured Treatment Device-Generic 0 0 0 0 0 20 0.00 0.00 TOTAL IMPERVIOUS COVER TREATED lac! 0.02 AREA CHECK•OK. TOTAL MANAGED TURF AREA TREATED(at' 0.16 AREA CHECK OK, TOTAL PHOSPHORUS REMOVAL REQUIRED ON SITE)Ib/yrjI 0.08 TOTAL PHOSPHORUS AVAILABLE FOR REMOVAL IN D.A.C(Ib/yr) 0.12 TOTAL PHOSPHORUS REMOVED WITHOUT RUNOFF REDUCTION PRACTICES IN D.A.C(lb/yr) 0.00 TOTAL PHOSPHORUS REMOVED WITH RUNOFF REDUCTION PRACTICES IN O.A.C(Ib/yr) 0.04 TOTAL PHOSPHORUS LOAD REDUCTION ACHIEVED IN D.A.C(Ib/yr) 0.04 TOTAL PHOSPHORUS REMAINING AFTER APPLYING BMP LOAD REDUCTIONS IN D.A C(lb/yr) 0.08 SEE WATER QUALITY COMPLIANCE TAB FOR SITE COMPLIANCE CALCULATIONS NITROGEN REMOVED WITH RUNOFF REDUCTION PRACTICES IN D.A C(lb/yr) 0.32 NITROGEN REMOVED WITHOUT RUNOFF REDUCTION PRACTICES IN D.A.C(Ib/yr) 0.00 TOTAL NITROGEN REMOVED IN D.A C(lb/yr) 0.32 2 0l4 328/2019 11.33AM wvse'u 6 L07JBLL >��I 00'0 00'0 00'0 00'0 0 00'0 00'0 00'0 00'0 00 0 00 0 0 00'0 00 0 (VW a,ed5 uadppalii 01 M0Ipaa4S'6 00'0 00'0 00'0 00'0 01 00'0 00'0 00'0 00'0 00'0 00'0 OS 00'0 00'0 (HH)Puod 001103100 pap00193'9 00'0 00'0 00'0 00'0 St 00 0 00 0 00'0 00'0 00'0 00'0 ST 00'O 00 0 Om)uopcapu 'L 00'0 00'0 00.0 00'0 09 00'0 00'0 00.0 00'0 000 00.0 OP 00'0 00'0 (HH)uollualaJ0l0•9 00'0 00'0 000 00'0 SO 00'0 00'0 00'0 000 00'0 00.0 si 00'0 00'0 (IRO alcmS 9.0 5 00'0 000. 00'0 00'0 0Z 00'0 00'0 00 0 00 0 00'0 00'0 00 00 0 00'0 9S'0 LE 0 s9'0 00'0 0Z 90'0 90'0 Om)lauuryls.e,a t. 00 o ao'o 00 0 'AN;•...:••S•. 00 0 00'0 00'0 00'0 00'0 00'0 5L 00'0 00'0 (HH)luaWJned al00aiumd'g 00 0 00.0 00'0 00'0 0e 00 0 00'0 000 00'0 00'0 000 0 00.0 00.0 00'0 00'0 00'0 00'0 09 00'0 00'0 00.0 00'0 00'0 00'0 OP 00.0 00'0 00'0 00'0 00'0 00'0 Sl 00•0 00 0 00'0 00'0 00'0 00'0 50 00 0 00 0 ao'o ao'a 00 0 00 0 0 00'0 CO 00'0 CO oo'o ao'a 0 000 000 00'0 00.0 00'0 00'0 0 00.0 00•0 (so)u011)ouu0-si0 d01)001f•Z IIMIIIIIMMIIIIIMI VA i.•.'•••.••• 00'0 000 00'0 0 00'0 00'0 000 00'0 00'0 • 0..•.. 00'0 00'0 •1HH)i00H P23ela9an'I (sql)pool (sql)a9l90eld (sql)aolhe1d (sql)sa3lpeld (%)A uaP913 (41)Peel NI)ao!Peld paAold w3 uaBallN AEI panowaH 01 pe01 uagoolN weal'sd(l wmi !ono wad Smo4dsogd Ag pano wad aq 01 a)liaeLd weaLlsumo0 8wulewad ua8o�llN Paleailun pool uaBoglN uaBayN lululewad snu o4 dso 4d _ -slsll umopdolp woii laala5-- S6T (04)3V0 ula ZT 0 (lA/ql)3 V'a I 0 v0 -L107.e0-6n H.vw..xls-mu.9dwa0-n•0•e wadn ee9l 1838_VRRM mo ReDev_Conpie_SpreeMh..t y3_082017a1oo DA C 0.00 0.00 0 0.00 0.00 0.0D 0.00 TOTAL RUNOFF REDUCTION IN D.A.C(fte) 39 NITROGEN REMOVED WITH RUNOFF REDUCTION PRACTICES IN D.A.C(Ib/yr) 0.32 SEE WATER QUALITY COMPLIANCE TAB FOR SITE CALCULATIONS(Information Only) 10.Wet Swale(Coastal Plain)(no RR) 0.00 0.00 25 0.00 0.00 0.00 0.00 0.00 0.00 35 0.00 0.00 0.00 0.00 11. Filtering Practiceti(no RR) 0.00 0.00 30 0.00 0.00 0.00 0.00 0.00 0.00 45 0.00 0.00 0.00 0.00 12.Constructed Wetland(no RR) 0.00 0.00 25 0.00 0.00 0.00 0.00 0.00 0.00 55 0.00 0.00 0.00 0.00 13.Wet Ponds(n0 RR) 0.00 0.00 30 0.00 0.00 0.00 0.00 0.00 0.00 20 0.00 0.00 0.00 0,00 0.00 0.00 40 0.00 0.00 0.00 0.00 0.00 0.00 30 0.00 0.00 0.00 0.00 14.Manufactured BMP(no RR) 0.00 0.00 0 0.00 0.00 0.00 0.00 0.00 0.00 0 0.00 0.00 0.00 0,00 0.00 0.00 0 0.00 0.00 0.00 0.00 4 of 328/2019 11.33 AM Site Results (Water Quality Compliance) . Area Checks 1 D.A.A D.A.B D.A.C D.A.D D.A.E AREA CHECK FOREST/OPEN SPACE(ac) 0.68 0.07 0.10 0.00 0.00 OK. IMPERVIOUS COVER(ac) 0.07 0.02 0.02 0.00 0.00 OK. IMPERVIOUS COVER TREATED(ac) 0.07 0.02 0.02 0.00 0.00 I OK. I MANAGED TURF AREA(ac). 0.31 0.09 0.16 0.00 0.00 OK. MANAGED TURF AREA TREATED(ac) 0.31 0.09 0.16 0.00 L 0.00 OK. AREA CHECK OK. OK. OK. OK. I OK. Site Treatment Volume(ft3) 2,373 Runoff Reduction Volume and TP By Drainage Area P- D.A.A I D.A.B D.A.C D.A.D D.A.E TOTAL j -- - RUNOFF REDUCTION VOLUME ACHIEVED(ft3) 95 29 39 0 0 163 TP LOAD AVAILABLE FOR REMOVAL(Ib/yr) 0.30 0.09 0.12 0.00 0.00 0.51 TP LOAD REDUCTION ACHIEVED(Ib/yr) 0.10 C.03 0.04 1 0.00 0.00 0.16 TP LOAD REMAINING (Ib/yr) 0.20 0.06 I 0.08 I 0.00 I 0.00 I 0.35 NITROGEN LOAD REDUCTION ACHIEVED(Ib/yr) 0.77 r 0.23 I 0.32 I 0.00 j 0.00 1.31 Total Phosphorus FINAL POST-DEVELOPMENT TP LOAD(Ib/yr) 1.49 TP LOAD REDUCTION REQUIRED(Ib/yr) 0.08 TP LOAD REDUCTION ACHIEVED (Ib/yr) 0.16 TP LOAD REMAINING(Ib/yr): 1.33 REMAINING TP LOAD REDUCTION REQUIRED(Ib/yr): 0.00 I** **TARGET TP REDUCTION EXCEEDED BY 0 08 LB/YEAR** Total Nitrogen(For Information Purposes) POST-DEVELOPMENT LOAD(Ib/yr) 10.66 NITROGEN LOAD REDUCTION ACHIEVED (Ib/yr) 1.31 REMAINING POST-DEVELOPMENT NITROGEN LOAD(Ib/yr) 9.35 vvginia Humph Reduction Methoa Worksheet DEQ Virginia Runoff Reduction Method Re-Development Compliance Spreadsheet -Version 3.0 BMP Design Specifications List 2013 Draft Stds&Specs Site Summary Project Title Innisfree Village Date 43552 Total Rainfall(in) 43 Total Disturbed Acreage 3.04 Site Land Cover Summary Pre-ReDevelopment Land Cover (acres) A soils B Soils C Soils D Soils Totals %of Total Forest/Open(acres) 0 00 1 95 0.00 0 00 1 95 64 Managed Turf(acres) 0.00 0.43 0.00 0 00 0.43 14 Impervious Cover(acres) 0.00 0 66 0.00 0 00 0 66 22 3 04 100 Post-ReDevelopment Land Cover (acres) A soils B Soils C Soils D Soils Totals %of Total Forest/Open(acres) 0 00 1 32 0.00 0.00 132 43 * Managed Turf(acres) 0 00 136 0 00 0 00 136 45 Impervious Cover(acres) 0.00 0.36 0 00 0 00 0 36 12 *Forest/Open Space areas must be protected in accordance with the Virginia Runoff Reduction Method 3 04 100 Site Tv and Land Cover Nutrient Loads Final Post-Development Post- Pre- Final Post-Development Post-ReDevelopment TP Post- Development Adjusted Pre- ReDevelopment (Post-ReDevelopment TP Load per acre Load per acre Impervious) ReDevelopment ReDevelopment TP Load per acre &New Im Pe ) (New Impervious) (Ib/acre/yr) (Ib/acre/yr) (Ib/acre/yr) Site Rv 0 22 0 22 -- 0 25 0.58 0.49 0.49 Treatment Volume(ft3) 2,373 2,373 -- 2,801 TP Load(Ib/yr) 1.49 1.49 -- 1 76 Total TP Load Reduction Required(Ib/yr) 0.08 0.08 0 Final Post-Development Load Pre- (Post-ReDevelopment&New Impervious) ReDevelopment TN Load(lb/yr) 10 66 12 59 Summary Print Virginia Runoff Reduction Method Worksheet Site Compliance Summary Maximum%Reduction Required Below 20% Pre-ReDevelopment Load Total Runoff Volume Reduction(ft3) 163 Total TP Load Reduction Achieved(lb/yr) 0 16 Total TN Load Reduction Achieved(Ib/yr) 1 31 Remaining Post Development TP Load (Ib/yr) 1.33 Remaining TP Load Reduction(Ib/yr) 0.00 **TARGET TP REDUCTION EXCEEDED BY 0.08 LB/YEAR** Required Summary Print Virginia Runoff Reduction Method Worksheet Drainage Area Summary D.A.A D.A.B D.A.C D.A.D D.A.E Total Forest/Open(acres) 0.68 0.07 0 10 0.00 0 00 0.85 Managed Turf(acres) 0 31 0.09 0.16 0 00 0 00 0 56 Impervious Cover(acres) 0.07 0 02 0.02 0.00 0.00 0 12 Total Area(acres) 1 06 0 18 0.28 0.00 0 00 1 53 Drainage Area Compliance Summary D.A.A D.A.B D.A.C D.A.D D.A.E Total TP Load Reduced(Ib/yr) 0 10 0.03 0.04 0 00 0 00 0 16 TN Load Reduced(Ib/yr) 0 77 0.23 0.32 0.00 0.00 1 31 Summary Print Virginia Runoff Reduction Method Worksheet Runoff Volume and CN Calculations 1-year storm 2-year storm 10-year storm Target Rainfall Event(in) 0.00 0 00 0.00 Drainage Areas RV&CN Drainage Area A Drainage Area B Drainage Area C Drainage Area D Drainage Area E CN 60 63 62 0 0 RR(ft3) 95 29 39 0 0 RV wo RR(ws-In) 0.00 0.00 0.00 0 00 0.00 1-year return period RV w RR(ws-in) 0 00 0.00 0.00 0.00 0.00 CN adjusted 100 100 100 0 0 RV wo RR(ws-In) 0.00 0.00 0 00 0.00 0.00 2-year return period RV w RR(ws-In) 0.00 0.00 0 00 0.00 0.00 CN adjusted 100 100 100 0 0 RV wo RR(ws-In) 0 00 0.00 0.00 0.00 0.00 10-year return period RV w RR(ws-In) 0.00 0.00 0.00 0.00 0.00 CN adjusted 100 100 100 0 0 Summary Print Appendix D Roof Leader Computations and Silt Fence Computations 05-08-19, Kenmare, Catch Basin and Front Roof Leader 10 yr Type II 24-hr Rainfall=6 00" Prepared by {enter your company name here} Printed 5/8/2019 HydroCAD® 10 00-20 s/n 03710 © 2017 HydroCAD Software Solutions LLC Subcatchment 4: Kenmare Catch Basin/Roof Drain Pipe Hydrograph 0 8 / ■Runoff 01 0 750111111111111111.11.... —I o 75 cfs I 1 a. - i . � 065 f- II 6.! 1 06 111111111111 ii R no i 3 , 5 � 055 z It 05 / a n .,ff a I, ,,g , . 0 45 i Li • . :P h 5. 8 3 04 01 C 5. 1 i u' 035 / 03 / d • N 9‘ 0 2 0 015 / 01 0 005 0 0 , .. , ..... .......... .. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) 05-08-19, Kenmare, Catch Basin and Front Roof Leader 10 yr Type 11 24-hr Rainfall=6.00" Prepared by {enter your company name here} Printed 5/8/2019 HydroCAD® 10 00-20 s/n 03710 ©2017 HydroCAD Software Solutions LLC Summary for Subcatchment 4: Kenmare Catch Basin/Roof Drain Pipe Runoff = 0 75 cfs @ 11.96 hrs, Volume= 1,665 cf, Depth> 5 18" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0 01-24 00 hrs, dt= 0.01 hrs Type II 24-hr Rainfall=6.00" Area (sf) CN Description 706 69 50-75% Grass cover, Fair, HSG B 3,152 98 Roof 3,858 93 Weighted Average 706 18 30% Pervious Area 3,152 81.70% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5 0 Direct Entry, 05-08-19, Laurel, Front Roof Leader 10 yr Rainfall Type II 24-hr Rainfall=6 00" Prepared by {enter your company name here} Panted 5/8/2019 HydroCAD® 10 00-20 s/n 03710 ©2017 HydroCAD Software Solutions LLC Subcatchment 4: Laurel Roof Drain Pipe Hydrograph lit , 0 481 — ■Runoff J ( ( ° �� Type II 24-hr 042. 038� Rainfall=6.00" ° / R • ff Area=2,190 sf 17° 3,/0 . Run I ff Vol -=1,051 cf w 028 ozs r7 • • •�' 3 0 24.. / LL 022t Tc=5.0 min 02 0 18, - CN=98 016 0 14- 012 01✓ 0081 / 0 06-r 004 - - 0 02- J 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) 05-08-19, Laurel, Front Roof Leader 10 yr Rainfall Type II 24-hr Rainfall=6 00" Prepared by {enter your company name here} Printed 5/8/2019 HydroCAD® 10.00-20 s/n 03710 ©2017 HydroCAD Software Solutions LLC Summary for Subcatchment 4: Laurel Roof Drain Pipe Runoff = 0 44 cfs @ 11 96 hrs, Volume= 1,051 cf, Depth> 5 76" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0 01-24 00 hrs, dt= 0.01 hrs Type II 24-hr Rainfall=6.00" Area (sf) CN Description * 2,190 98 Roof 2,190 100 00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5 0 Direct Entry, l / / / "i.PI ;� v� via tJr«sHn►t t / 7 • f �• PROP TRANSF( 7---- / ,' — _ _ (FURNISHED Al 11,'' /- — �'`� BY DOMINION E < ._ _ PRO 401 � ��i -- � . (KEN i BID ITEM#5 $' j / ets PROP WATERLINE i R 2,005 LF / T' WELL FRD-4A moo!� \ TS MU PS ` / (OPT B) �`' / e. O `� -1 o!• ../ t f / ,ti ) fr'N..," PROP 1500 GAL ' FE' 0,--- SF z. SEPTIC TANK 0 / / w / ' ' j , '� '' o t,. 0 PARKING/ w TP•• ��o /� / !7 \y STAGING 4 5 E s. i t /.------ illi O 0 PARKINGI DC / .� i C •• ,,, %°�� -10 +/�;� \ STAGING O — •\ . / • ` e - , . ......_ PROP 500 GAL e f i' -1 / TOPSOIL ,./ p i PROPANE TANK "i •t I TP STOCKPILE i y FOR KENMARE I '� / ' '.- PS 1 / TS �, .) • / \- 1 r �_ / / I _) ��� SILT FENCE COMPLIANCE COMPUTATIONS r � V 1 1 - . � SF �_ Note: The silt fence was checked in the most critical area. BASE BID O ,•G / PROP WATERLINE ' l Requirement: '/4 acre drainage area per 100 LF of silt fence. / WELL#5-OAKWOOD TENAX FENCE 1 :`' . (OPT A) ' ' t Kenmare: \ ' LIMITS OF� �\' _< DISTURBANCE SF =� 270 LF of Silt Fence,therefore 2.70 x 0.25 acre=0.68 acre I` x Since actual area 0.43 acre<0.68 acre therefore OK tr 2 ( \PARKING! _� , \ \ //� \ STAGING \ / 4 E �, EX WELL#4 -LAUREL , / t� 2 5 B ,�• ..c .• \ - \ �F `allik PARKING/ /i DC `\ PROP WATERLINE - TP STAGING O _ � a ' \1 �s -EX PROPANE (2) EX PROPANENo TANK DEDICATED TANKS DEDICATED — _ i I ~'� • FOR LAUREL FOR GENERATOR TOPSOIL# 2 o/ 1► Q\ • _ —EX GENERATOR STOCKPI i B2 � � -����� � _• _ �• TO BE x / is cy/Q-LY/ \� ��� +\` c •- — . RELOCATED . t - B1 . c c . — \ ��.� , ` / �,v (%mac . ,- ' Ntilli `��� _ =� � EX TRANSFORMER / / r "o ., ,0. sue_.9-- -- -.J� PROP POWER FEED 00)j Ve (LAUREL) � )A ' — , /// ..� - --074- -',r, IC � � SF ETANKTC „, . ..„--, _0.1--.. EX CO A. 1 I • -7 _,. 10 -- 0 , : ofigAmi.70,,,,ii,i, .......z.c,,, -4.1.7., . 1 i 2. .:;--,,.....____,„.......-- „.:-.--i 0 „........)( / - . \)------. ..,:;Z'i • __ ,, + LIMITS OF DISTURBANCE / \ \ ��.• ;s.,,: f ` SF \� `� • SANITARY CO, TYP EX DBE-��\ • X SEPTIC - 7 TA : TENAX / • SETTLING AREA - FE' "'- 1' DEEP WITH GRAVEL OUTLET C FOR PAVED CONSTRUCTION •� _ EX SEPTIC - SILT FENCE COMPLIANCE COMPUTATIONS • ENTRANCE - USE VDOT#3 STONE TANK (A) ,� Note: The silt fence was checked in the most critical area. ` • • Requirement: V.acre drainage area per 100 LF of silt fence. ADDITIONAL EX DB 1 %LT. RESERVE Laurel: DRAINFIELD EX YARD HYD �-EX SB 90' x 100' (FOR GARDEN) 115 LF of Silt Fence, therefore 1.15 x 0.25 acre=0.29 acre _ EX DB =UTURE OPTION r EX DIST BOX �/� Since actual area 0.27 acre<0.29 acre therefore OK InT INCI IJDFD IN