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WPO202000017 Plan - Stormwater 2020-07-20
SHIMP ENGINEERING, P.C. Design Focused Engineering July 17, 2020 County of Albemarle Department of Community Development 401 McIntire Road Charlottesville, VA 22902 Regarding: Proffit Road Townhomes South Stormwater Management Plan Dear David, The purpose of this project is to build 40 single family attached units on the southern side of Proffit Road. The total area of disturbance is 3.34 acres. Water Quantity Runoff from the site in the predevelopment condition is analyzed at one point labeled POA. The post - development condition runoff is collected and piped to an underground detention system comprised of StormTech MC4500 chambers and an isolation row, which outlets to POA. The proposed storm sewer will outlet into an existing channel further downstream. Runoff from the site will be released at rates that comply with the energy balance equation set forth in 9VAC25-870-66-B(3). The calculations are summarized in the table below. Please note that a small portion of the drainage area to POA is from offsite. The flow from offsite was included in the energy balance equation. PROFFIT ROAD TOWNHOMES SOUTH 24 Hr 1 year Storm: Qermo I.F.'(Q�RV.~)/RveNmxe Dmin eA a: PQA Qw•ar~ - 1.14 Q'. 0.12 �r2ory.bm 0.M M.Q� ' = 0.2cfa RVor am.e - 0.400 JQ.= 0.42 ck Pro Development Post Develo went 10 r 7.20 7.02 Water Quality According to the VRRM spreadsheet included in this packet, the target phosphorus load reduction is 3.14 lb/yr. The StormTech chambers with the isolator row are rated for 40%D phosphorous removal, resulting in 1.77 Ib/yr phosphorous removal. The remaining phosphorous load 1.37 Ib/yr will be effectively reduced by the purchase of nutrient credits. 912 E. High Sr. Charlottesville, VA 22902 1434.227.5140 1 shimp-engineering.com Contents: Water Quantity Calculations: Pre -Development Drainage Area Map Pre -Development HydroCAD Report Post -Development Drainage Area Maps Post -Development Inlets Drainage Area Maps Post -Development HydroCAD Analysis Energy Balance Equations TOC Calculations Nomographs VDOT LD-204 VDOT LD-209 VDOT LD-347 Water Quality Calculations: Pre -Development VRRM Landuse Map Post -Development VRRM Landuse Map VRRM Redevelopment Spreadsheets Independent Reports: Excerpt from NRCS Soils Report NOAA Precipitation Report Water Quantity Calculations: Pre -Development Drainage Area Map Pre -Development HydroCAD Report Post -Development Drainage Area Maps Post -Development Inlets Drainage Area Maps Post -Development HydroCAD Analysis Energy Balance Equations TOC Calculations Nomographs VDOT LD-204 VDOT LD-209 VDOT LD-347 PRE -DEVELOPMENT DRAINAGE AREA MAP Brush TOTAL\\OFFSITE AREA= o —_0.52 AC —'aza, 5M se Trees IRO 0 0 0 FM m a \ \ \ GV 0 / 1 O� SWELL TBR `v v \ ll J� PRE DEV. IMPE AREA =0.24 O D\V. WOOD AREA =0,37 AC _----- OF CpNCENT v - - - o ---- 5z1 --- 18.0 MINU-1 � �J ® , 511 I / 1Dense_ — _---------_------------------------- j `IoN - — F I ON — — — — — — — �1111111"11' 11"n ���©TOTAL. I i ,- 01 1 1 1 401 1 1 118d I° C Scale: 1 "=40' 1S 2S PreDev Onsite PreDev Offsite 3L POA1 SubCat Reach on Link Drainage Diagram for PreDev Prepared by (enter your company name here}, Printed 7/17/2020 HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC POST DEV PreDev Type 1124-hr 1 yr, 24 hr Rainfall=2.97 Prepared by {enter your company name here} Printed 7/17/2020 HydroCAD09.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 2 Time span=0.00-36.00 hrs, dt=0.05 hrs, 721 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: PreDev Onsite Runoff Area=3.090 ac 7.77% Impervious Runoff Depth=0.46" Tc=18.0 min CN=64 Runoff=1.18 cfs 0.117 of Subcatchment 2S: PreDev Offsite Runoff Area=0.520 ac 0.00% Impervious Runoff Depth=0.35' Tc=18.0 min CN=61 Runoff=0.13 cfs 0.015 of Link 3L: POA1 Inflow=1.31 cfs 0.133 of Primary=1.31 cfs 0.133 of Total Runoff Area = 3.610 ac Runoff Volume = 0.133 of Average Runoff Depth = 0.44" 93.35% Pervious = 3.370 ac 6.65% Impervious = 0.240 ac POST DEV PreDev Type 1124-hr 1 yr, 24 hr Rainfall=2.97' Prepared by (enter your company name here) Printed 7/17/2020 HydroCAD09.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 3 Summary for Subcatchment 1 S: PreDev Onsite Runoff = 1.18 cfs @ 12.15 hrs, Volume= 0.117 af, Depth= 0.46" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-36.00 hrs, dt= 0.05 hrs Type II 24-hr 1 yr, 24 hr Rainfall=2.97" Area (ac) CN Description 0.370 58 Woods/grass comb., Good, HSG B 2.480 61 >75% Grass cover, Good, HSG B 0.240 98 Paved parking, HSG B 3.090 64 Weighted Average 2.850 92.23% Pervious Area 0.240 7.77% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 18.0 Direct Entry, POST DEV PreDev Type 1124-hr 1 yr, 24 hr Rainfall=2.97" Prepared by {enter your company name here) Printed 7/17/2020 HvdroCAD® 9.10 s/n 07054 02011 HvdroCAD Software Solutions LLC Paae 4 Summary for Subcatchment 2S: PreDev Offsite Runoff = 0.13 cfs @ 12.16 hrs, Volume= 0.015 af, Depth= 0.35" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-36.00 hrs, dt= 0.05 hrs Type II 24-hr 1 yr, 24 hr Rainfall=2.97" Area (ac) CN Description 0.520 61 >75% Grass cover. Good. HSG B 0.520 100.00% Pervious Area Tc Length Slope Velocity Capacity Description 18.0 Direct Entry, POST DEV PreDev Type 1124-hr 1 yr, 24 hr Rainfall=2.97" Prepared by {enter your company name here} Printed 7/17/2020 HvdroCAD® 9.10 s/n 07054 02011 HvdroCAD Software Solutions LLC Paae 5 Summary for Link X: POM Inflow Area = 3.610 ac, 6.65% Impervious, Inflow Depth = 0.44" for 1 yr, 24 hr event Inflow = 1.31 cfs @ 12.15 hrs, Volume= 0.133 of Primary = 1.31 cfs @ 12.15 hrs, Volume= 0.133 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-36.00 hrs, dt= 0.05 hrs POST DEV PreDev Type 1124-hr 10 yr, 24 hr Rainfall=5.43" Prepared by {enter your company name here} Printed 7/17/2020 HydroCAD09.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 6 Time span=0.00-36.00 hrs, dt=0.05 hrs, 721 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: PreDev Onsite Runoff Area=3.090 ac 7.77% Impervious Runoff Depth=1.87" Tc=18.0 min CN=64 Runoff=6.51 cfs 0.481 of Subcatchment 2S: PreDev Offsite Runoff Area=0.520 ac 0.00% Impervious Runoff Depth=1.63" Tc=18.0 min CN=61 Runoff=0.94 cfs 0.071 of Link 3L: POA1 Inflow=7.45 cfs 0.551 of Primary=7.45 cfs 0.551 of Total Runoff Area = 3.610 ac Runoff Volume = 0.551 of Average Runoff Depth = 1.83" 93.35% Pervious = 3.370 ac 6.65% Impervious = 0.240 ac POST DEV PreDev Type 1124-hr 10 yr, 24 hr Rainfall=5.43" Prepared by (enter your company name here) Printed 7/17/2020 HydroCAD09.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 7 Summary for Subcatchment 1 S: PreDev Onsite Runoff = 6.51 cfs @ 12.12 hrs, Volume= 0.481 af, Depth= 1.87" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-36.00 hrs, dt= 0.05 hrs Type II 24-hr 10 yr, 24 hr Rainfall=5.43" Area (ac) CN Description 0.370 58 Woods/grass comb., Good, HSG B 2.480 61 >75% Grass cover, Good, HSG B 0.240 98 Paved parking, HSG B 3.090 64 Weighted Average 2.850 92.23% Pervious Area 0.240 7.77% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 18.0 Direct Entry, POST DEV PreDev Type 11 24-hr 10 yr, 24 hr Rainfall=5.43" Prepared by {enter your company name here) Printed 7/17/2020 HvdroCAD® 9.10 s/n 07054 02011 HvdroCAD Software Solutions LLC Paae 8 Summary for Subcatchment 2S: PreDev Offsite Runoff = 0.94 cfs @ 12.12 hrs, Volume= 0.071 af, Depth= 1.63" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-36.00 hrs, dt= 0.05 hrs Type II 24-hr 10 yr, 24 hr Rainfall=5.43" Area (ac) CN Description 0.520 61 >75% Grass cover, Good, HSG B 0.520 100.00% Pervious Area Tc Length 18.0 Description Direct Entry, POST DEV PreDev Type ll 24-hr 10 yr, 24 hr Rainfall=5.43" Prepared by !enter vour comoanv name here} Printed 7/17/2020 Summary for Link 3L: POM Inflow Area = 3.610 ac, 6.65% Impervious, Inflow Depth = 1.83" for 10 yr, 24 hr event Inflow = 7.45 cfs @ 12.12 hrs, Volume= 0.551 of Primary = 7.45 cfs @ 12.12 hrs, Volume= 0.551 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-36.00 hrs, dt= 0.05 hrs POST -DEVELOPMENT DRAINAGE MAP v ��o TREATED FARIEA ao El POLE a� a� a�—a�V ,�� 0.3D A a� �—'a� — ��a� `� nL — , — — — �- --- --� -- - - — POLE \ / �` k 7 k. kkk k '\k �,k } kk kkk •k k, kM1:. g�\ /� /// 3b" k\ } O ..\ DI S N �... �. k3 k kk k k +l k"\ k k k k_ k k k'Y '� } k .•Y 1 2 F �k-k +�, STELI I ON SI I�\\ REATED X 53p k '� kl I 'szy AC 3�1 b@- / k} k k k , k k k \ } k k\ \. 28 k\ k }i k } k �f�'��cccc$6,� k k k\ k � •.,'. k I 1 � _ k •. '\" } k k k \} ' d } � k k k k \- 1 ,.N•''.. U) \ \I 8kDl AN \',k k% k �, szo- 1 3�' kk k 1 DIP3C W all }k"'\.X,. k'r• 36 N '�� ,k PE k y k k k kk/k h k k:. k kk k k\}} k} k kAYW \\ O \\ \\ k } '\" k k Ohl ^\ - '\ k k }\H- k ) p k kk k k k k k, k ` k\\ k }\ � k k\� k N• R el k k k kk �} } k O\ k\ k k k k\ k k �, r I I I 20' DR,AINAG \.�.,,�� C SE uo k / k k �, k k k k NS�fErCTI J / k k kk k k k k e k k} kk } '\ k k k k •_k kkry y! A PORT / k } ¢ N k k _ _ a, } k '� \, k �.s' k ..i' k k 'r k k "\ ,'fI k k } k.•., I k II k DRAINAGE EASEMENTxi k k k k k k 1 k k X_k k k L.k�.. �.'s—.k k.k k �. 11' k k yak/k k k k k•'h 1 !q LEGEND ® OFFSITE TO STORMTECH MC-4500 I I I I kkk g' SYSTEM TO BE TREATED /i I I I I I I _■ k k ONSITE TO STORMTECH MC-4500 SYSTEM TO BE TREATED e°' ONSITE TREATED Z — — '� AREA 2.74 AC \\ ®OFFSITE TO POA 1 NOT / _ OFFSITE O I TREATED -- �'b_NTfREATED 40 0 0 8 N 0 \\ {} ONSITE TO POA 1 NOT AREA 0.22 AC TREATED Scale: 1"=40' INLETS DRAINAGE AREA MAP I a — — — — — — — —55T-- u\ 1 � \ _ Dense Trees _\ 1 ushN <� -' IN%ETb�AUyAGE AREAS \�\ i �`r - - T' EL PED 0 \ 1 \ o \ POLE OL 1 -�\ - - - - r POLE �\ 1 1 -- sze \` �`\ \ 6 ION \\ Dense Trees N22'24'08"E 482.68' FOUND � 1J 581 I /� LOT 31 5za LOT 30 \ \ I o --FE-5a7` \\ `L9T 32 LOT 33 LOT 34 LT 35 LOT 3fi LOT 3 LOT 3 LT 3 LOT 4 j szz, x I ` \ I FFE�531. FFE 531. FE 533. FF 534. FFE 534. FFE 535. FFE 4. F�iS - _ - \ \ 2 F 32 o STE L / LOT 29 `\ \ \ \ / so 3LE VEI I -�\\ FFE 527.0 �\ • \\ \\ � / � - - 2\\ \ � \ FFEE 8D0 LOT 27 I V \ I \ \ \ ® \ 8" DI SAN zi 0 26 8\ DI SAN _ --4 II (• o 5 5 mFFE�535.5 $ �/ Sze J � DI 3B \ I -- iN 131 12' DI-3C W AI : '..:. - / 0� •)L 1� \l N LOT 22 f I--N \ � _,,•.-----.: . A7,. � `� LOT 5 \ FFE 526.5 m \ `\ \ 9 p v FFE 53 \ x LO7 i 6 \ FLo 9�1.5 A O FFE 28.0 -� LOT 23 \ \ ➢+ I LOT 5.5 3 0 1 I FFE 526.5 O LOT 0 1 FFE 53 FFOE 280 �..: \ LOT FFE 53stl ° - LOT 24 i /' FEE-52Z1` szz _ _ _ LO 111 43 LO 18 '.y. �� NSPECTI..FFE _ J FFEI528.0LOT 25 (V�e 81 PORT (N 'a I \ E FFE 527.0 / T �2 LO 19 I FFE / ---_ T 26 FFE �528.5 1 LOT 5 \ 1 sza - // / a FFE 5350 \\ I FOE 527.0 LOT 3 - \ �0 20 ' : • r FFE 5 5 I / I T 6 FF'E�548� / / // 1 FFE 534. I ry (. 1 III II II I q I Dense T+e LJF 21 FFOE IRO 26 ----FFEV 8.5 _ ;1 n �F 534.5 FOUND _ -N - _ _ _ _ TOT513.0 _ ____________.sze-____ Mp \ OT 38.0 / - - s i' n 2 4 z8 - _ a32 1 446 IR g /-S�26'08'59"W 169.50, 1w ij' i/ I I I Dense Trees —L_ - 530I,j Q — ' IRO i e FOUND 925 — SJ2 — \ / l�5 40 40 \ Scale: 1 "=40' 2S Onsite Treated iS 3S Offsite Treated Onsite ntreated 4S 5P Offsite Untreated StormTech 6L POA Subcat Reach on Link Drainage Diagram for PostDev2 Prepared by {enter your company name here}, Printed 7/16/2020 HydroCAD ) 9.10 s/n 07054 0 2011 HydroCAD Software Solutions LLC POST DEV PostDev2 Type 11 24-hr 1 yr, 24 hr Rainfall=2.97" Prepared by {enter your company name here} Printed 7/16/2020 HydroCAD09.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 2 Time span=0.00-48.00 hrs, dt=0.05 hrs, 961 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: Offsite Treated Runoff Area=0.300 ac 0.00% Impervious Runoff Depth=0.35" Tc=5.0 min CN=61 Runoff=0.14 cfs 0.009 of Subcatchment 2S: Onsite Treated Runoff Area=2.740 ac 67.88% Impervious Runoff Depth=1.64" Tc=5.0 min CN=86 Runoff=8.02 cfs 0.374 of Subcatchment 3S: Onsite Untreated Runoff Area=0.354 ac 1.13% Impervious Runoff Depth=0.35" Tc=5.0 min CN=61 Runoff=0.17 cfs 0.010 of Subcatchment 4S: Offsite Untreated Runoff Area=0.220 ac 0.00% Impervious Runoff Depth=0.35" Tc=5.0 min CN=61 Runoff=0.10 cfs 0.006 of Pond 5P: StormTech Peak Elev=521.10' Storage=10,235 cf Inflow=8.14 cfs 0.383 of Outflow=0.18 cfs 0.383 of Link 6L: POA Inflow=0.42 cfs 0.400 of Primary=0.42 cfs 0.400 of Total Runoff Area = 3.614 ac Runoff Volume = 0.400 of Average Runoff Depth = 1.33" 48.42% Pervious = 1.750 ac 51.58% Impervious = 1.864 ac POST DEV PostDev2 Type 1124-hr 1 yr, 24 hr Rainfall=2.97" Prepared by {enter your company name here) Printed 7/16/2020 HvdroCAD® 9.10 s/n 07054 02011 HvdroCAD Software Solutions LLC Paae 3 Summary for Subcatchment 1 S: Offsite Treated Runoff = 0.14 cfs @ 11.99 hrs, Volume= 0.009 af, Depth= 0.35" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 1 yr, 24 hr Rainfall=2.97" Area (ac) CN Description 0.300 61 >75% Grass cover, Good, HSG B 0.300 100.00% Pervious Area Tc Length Description Direct Entry, POST DEV PostDev2 Type 1124-hr 1 yr, 24 hr Rainfall=2.97' Prepared by {enter your company name here} Printed 7/16/2020 HydroCAD09.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 4 Summary for Subcatchment 2S: Onsite Treated Runoff = 8.02 cfs @ 11.96 hrs, Volume= 0.374 af, Depth= 1.64" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 1 yr, 24 hr Rainfall=2.97" Area (ac) CN Description 1.860 98 0.880 61 >75% Grass cover, Good, HSG B 2.740 86 Weighted Average 0.880 32.12% Pervious Area 1.860 67.88% Impervious Area Tc Length Slope Velocity Capacity Description 5.0 Direct Entry, POST DEV PostDev2 Type 1124-hr 1 yr, 24 hr Rainfall=2.97' Prepared by {enter your company name here} Printed 7/16/2020 HydroCAD09.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 5 Summary for Subcatchment 3S: Onsite Untreated Runoff = 0.17 cfs @ 11.99 hrs, Volume= 0.010 af, Depth= 0.35" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 1 yr, 24 hr Rainfall=2.97" Area (ac) CN Description 0.350 61 >75% Grass cover, Good, HSG B 0.004 98 Paved parking, HSG B 0.354 61 Weighted Average 0.350 98.87% Pervious Area 0.004 1.13% Impervious Area Tc Length Slope Velocity Capacity Description 5.0 Direct Entry, POST DEV PostDev2 Type 1124-hr 1 yr, 24 hr Rainfall=2.97' Prepared by (enter your company name here) Printed 7/16/2020 HydroCAD09.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 6 Summary for Subcatchment 4S: Offsite Untreated Runoff = 0.10 cfs @ 11.99 hrs, Volume= 0.006 af, Depth= 0.35" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 1 yr, 24 hr Rainfall=2.97" Area (ac) CN Description 0.220 61 >75% Grass cover. Good. HSG B 0.220 100.00% Pervious Area Tc Length Slope Velocity Capacity Description 5.0 Direct Entry, POST DEV PostDev2 Type 1124-hr 1 yr, 24 hr Rainfall=2.97' Prepared by (enter your company name here) Printed 7/16/2020 HydroCAD09.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 7 Summary for Pond 5P: StormTech Inflow Area = 3.040 ac, 61.18% Impervious, Inflow Depth = 1.51" for 1 yr, 24 hr event Inflow = 8.14 cfs @ 11.96 hrs, Volume= 0.383 of Outflow = 0.18 cfs @ 15.79 hrs, Volume= 0.383 af, Atten= 98%, Lag= 229.9 min Primary = 0.18 cfs @ 15.79 hrs, Volume= 0.383 of Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Peak Elev= 521.10' @ 15.79 hrs Surf.Area= 4,737 sf Storage= 10,235 cf Plug -Flow detention time= 667.4 min calculated for 0.382 of (100% of inflow) Center -of -Mass det. time= 667.9 min ( 1,492.0 - 824.1 ) Volume Invert Avail.Storage Storage Description #1 516.72' 919 cf 36.0" D x 130.01 Pipe Storage S= 0.0098 7' #2 517.50' 11,919 cf 47.46'W x 99.801 x 8.30'H STONE STORAGE 39,313 cf Overall - 9,515 cf Embedded = 29,798 cf x 40.0% Voids #3 519.50' 9,158 cf StormTech MC-4500 x 86 Inside #2 Effective Size= 90.4"W x 60.0"H => 26.46 sf x 4.031 = 106.5 cf Overall Size= 100.0"W x 60.0"H x 4.331 with 0.31' Overlap #4 519.50' 357 cf StormTech MC-4500 Cap x 10 Inside #2 Effective Size= 63.5"W x 59.0"H => 15.25 sf x 2.341 = 35.7 cf Overall Size= 90.2"W x 59.4"H x 2.92'L with 0.58' Overlap 22,353 cf Total Available Storage Device Routina Invert Outlet Devices #1 Primary 516.72' 24.0" Round Culvert L= 77.4' Ke= 0.600 Inlet / Outlet Invert= 516.72' / 516.10' S= 0.0080 '/' Cc= 0.900 n= 0.012 #2 Device 1 516.72' 1.8" Vert. Orifice/Grate-l-YR C= 0.600 #3 Device 1 521.40' 13.0" Vert. Orifice/Grate-10-YR C= 0.600 #4 Primary 523.40' Custom Weir/Orifice, Cv= 2.62 (C= 3.28) Head (feet) 0.00 2.00 Width (feet) 4.00 4.00 Primary OutFlow Max=0.18 cfs @ 15.79 hrs HW=521.10' (Free Discharge) 1- Culvert (Passes 0.18 cfs of 26.06 cfs potential flow) �2=Orifice/Grate-1-YR (Orifice Controls 0.18 cfs @ 9.99 fps) 3=Orifice/Grate-10-YR ( Controls 0.00 cfs) =Custom Weir/Orifice ( Controls 0.00 cfs) POST DEV PostDev2 Type 1124-hr 1 yr, 24 hr Rainfall=2.97" Prepared by {enter your company name here} Printed 7/16/2020 HvdroCAD® 9.10 s/n 07054 02011 HvdroCAD Software Solutions LLC Paae 8 Summary for Link 6L: POA Inflow Area = 3.614 ac, 51.58% Impervious, Inflow Depth = 1.33" for 1 yr, 24 hr event Inflow = 0.42 cfs @ 11.99 hrs, Volume= 0.400 of Primary = 0.42 cfs @ 11.99 hrs, Volume= 0.400 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs POST DEV PostDev2 Type 1124-hr 10 yr, 24 hr Rainfall=5.43" Prepared by {enter your company name here} Printed 7/16/2020 HydroCAD09.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 9 Time span=0.00-48.00 hrs, dt=0.05 hrs, 961 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: Offsite Treated Runoff Area=0.300 ac 0.00% Impervious Runoff Depth=1.63" Tc=5.0 min CN=61 Runoff=0.87 cfs 0.041 of Subcatchment 2S: Onsite Treated Runoff Area=2.740 ac 67.88% Impervious Runoff Depth=3.87" Tc=5.0 min CN=86 Runoff=18.25 cfs 0.884 of Subcatchment 3S: Onsite Untreated Runoff Area=0.354 ac 1.13% Impervious Runoff Depth=1.63" Tc=5.0 min CN=61 Runoff=1.02 cfs 0.048 of Subcatchment 4S: Offsite Untreated Runoff Area=0.220 ac 0.00% Impervious Runoff Depth=1.63" Tc=5.0 min CN=61 Runoff=0.63 cfs 0.030 of Pond 5P: StormTech Peak Elev=523.53' Storage=17,709 cf Inflow=19.11 cfs 0.925 of Outflow=6.36 cfs 0.925 of Link 6L: POA Inflow=7.02 cfs 1.003 of Primary=7.02 cfs 1.003 of Total Runoff Area = 3.614 ac Runoff Volume = 1.003 of Average Runoff Depth = 3.33" 48.42% Pervious = 1.750 ac 51.58% Impervious = 1.864 ac POST DEV PostDev2 Type 11 24-hr 10 yr, 24 hr Rainfall=5.43" Prepared by {enter your company name here) Printed 7/16/2020 HvdroCAD® 9.10 s/n 07054 02011 HvdroCAD Software Solutions LLC Paae 10 Summary for Subcatchment 1 S: Offsite Treated Runoff = 0.87 cfs @ 11.97 hrs, Volume= 0.041 af, Depth= 1.63" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 10 yr, 24 hr Rainfall=5.43" Area (ac) CN Description 0.300 61 >75% Grass cover, Good, HSG B 0.300 100.00% Pervious Area Tc Length Description Direct Entry, POST DEV PostDev2 Type 1124-hr 10 yr, 24 hr Rainfall=5.43" Prepared by {enter your company name here} Printed 7/16/2020 HydroCAD09.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 11 Summary for Subcatchment 2S: Onsite Treated Runoff = 18.25 cfs @ 11.95 hrs, Volume= 0.884 af, Depth= 3.87" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 10 yr, 24 hr Rainfall=5.43" Area (ac) CN Description 1.860 98 0.880 61 >75% Grass cover, Good, HSG B 2.740 86 Weighted Average 0.880 32.12% Pervious Area 1.860 67.88% Impervious Area Tc Length Slope Velocity Capacity Description 5.0 Direct Entry, POST DEV PostDev2 Type 1124-hr 10 yr, 24 hr Rainfall=5.43" Prepared by {enter your company name here} Printed 7/16/2020 HydroCAD09.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 12 Summary for Subcatchment 3S: Onsite Untreated Runoff = 1.02 cfs @ 11.97 hrs, Volume= 0.048 af, Depth= 1.63" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 10 yr, 24 hr Rainfall=5.43" Area (ac) CN Description 0.350 61 >75% Grass cover, Good, HSG B 0.004 98 Paved parking, HSG B 0.354 61 Weighted Average 0.350 98.87% Pervious Area 0.004 1.13% Impervious Area Tc Length Slope Velocity Capacity Description 5.0 Direct Entry, POST DEV PostDev2 Type 11 24-hr 10 yr, 24 hr Rainfall=5.43" Prepared by {enter your company name here) Printed 7/16/2020 HvdroCAD® 9.10 s/n 07054 02011 HvdroCAD Software Solutions LLC Paae 13 Summary for Subcatchment 4S: Offsite Untreated Runoff = 0.63 cfs @ 11.97 hrs, Volume= 0.030 af, Depth= 1.63" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 10 yr, 24 hr Rainfall=5.43" Area (ac) CN Description 0.220 61 >75% Grass cover, Good, HSG B 0.220 100.00% Pervious Area Tc Length Description Direct Entry, POST DEV PostDev2 Type 1124-hr 10 yr, 24 hr Rainfall=5.43" Prepared by (enter your company name here) Printed 7/16/2020 HydroCAD09.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 14 Summary for Pond 5P: StormTech Inflow Area = 3.040 ac, 61.18% Impervious, Inflow Depth = 3.65" for 10 yr, 24 hr event Inflow = 19.11 cfs @ 11.95 hrs, Volume= 0.925 of Outflow = 6.36 cfs @ 12.08 hrs, Volume= 0.925 af, Atten= 67%, Lag= 7.8 min Primary = 6.36 cfs @ 12.08 hrs, Volume= 0.925 of Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Peak Elev= 523.53' @ 12.08 hrs Surf.Area= 4,737 sf Storage= 17,709 cf Plug -Flow detention time= 396.5 min calculated for 0.924 of (100% of inflow) Center -of -Mass det. time= 397.6 min ( 1,197.7 - 800.2 ) Volume Invert Avail.Storage Storage Description #1 516.72' 919 cf 36.0" D x 130.01 Pipe Storage S= 0.0098 7' #2 517.50' 11,919 cf 47.46'W x 99.801 x 8.30'H STONE STORAGE 39,313 cf Overall - 9,515 cf Embedded = 29,798 cf x 40.0% Voids #3 519.50' 9,158 cf StormTech MC-4500 x 86 Inside #2 Effective Size= 90.4"W x 60.0"H => 26.46 sf x 4.031 = 106.5 cf Overall Size= 100.0"W x 60.0"H x 4.331 with 0.31' Overlap #4 519.50' 357 cf StormTech MC-4500 Cap x 10 Inside #2 Effective Size= 63.5"W x 59.0"H => 15.25 sf x 2.341 = 35.7 cf Overall Size= 90.2"W x 59.4"H x 2.92'L with 0.58' Overlap 22,353 cf Total Available Storage Device Routina Invert Outlet Devices #1 Primary 516.72' 24.0" Round Culvert L= 77.4' Ke= 0.600 Inlet / Outlet Invert= 516.72' / 516.10' S= 0.0080 '/' Cc= 0.900 n= 0.012 #2 Device 1 516.72' 1.8" Vert. Orifice/Grate-l-YR C= 0.600 #3 Device 1 521.40' 13.0" Vert. Orifice/Grate-10-YR C= 0.600 #4 Primary 523.40' Custom Weir/Orifice, Cv= 2.62 (C= 3.28) Head (feet) 0.00 2.00 Width (feet) 4.00 4.00 Primary OutFlow Max=6.25 cfs @ 12.08 hrs HW=523.51' (Free Discharge) 1- Culvert (Passes 5.78 cfs of 34.12 cfs potential flow) �2=Orifice/Grate-1-YR (Orifice Controls 0.22 cfs @ 12.48 fps) 3=Orifice/Grate-10-YR (Orifice Controls 5.56 cfs @ 6.03 fps) =Custom Weir/Orifice (Weir Controls 0.47 cfs @ 1.08 fps) POST DEV PostDev2 Type ll 24-hr 10 yr, 24 hr Rainfall=5.43" Prepared by !enter vour comoanv name here} Printed 7/16/2020 Summary for Link 6L: POA Inflow Area = 3.614 ac, 51.58% Impervious, Inflow Depth = 3.33" for 10 yr, 24 hr event Inflow = 7.02 cfs @ 12.06 hrs, Volume= 1.003 of Primary = 7.02 cfs @ 12.06 hrs, Volume= 1.003 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs POST DEV PostDev2 Type 1124-hr 100yr, 24 hr Rainfall=8.90" Prepared by {enter your company name here} Printed 7/16/2020 HydroCAD09.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 16 Time span=0.00-48.00 hrs, dt=0.05 hrs, 961 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: Offsite Treated Runoff Area=0.300 ac 0.00% Impervious Runoff Depth=4.14" Tc=5.0 min CN=61 Runoff=2.24 cfs 0.104 of Subcatchment 2S: Onsite Treated Runoff Area=2.740 ac 67.88% Impervious Runoff Depth=7.21" Tc=5.0 min CN=86 Runoff=32.68 cfs 1.645 of Subcatchment 3S: Onsite Untreated Runoff Area=0.354 ac 1.13% Impervious Runoff Depth=4.14" Tc=5.0 min CN=61 Runoff=2.64 cfs 0.122 of Subcatchment 4S: Offsite Untreated Runoff Area=0.220 ac 0.00% Impervious Runoff Depth=4.14" Tc=5.0 min CN=61 Runoff=1.64 cfs 0.076 of Pond 5P: StormTech Peak Elev=524.97' Storage=20,778 cf Inflow=34.91 cfs 1.749 of Outflow=33.58 cfs 1.748 of Link 6L: POA Inflow=37.81 cfs 1.946 of Primary=37.81 cfs 1.946 of Total Runoff Area = 3.614 ac Runoff Volume = 1.947 of Average Runoff Depth = 6.47" 48.42% Pervious = 1.750 ac 51.58% Impervious = 1.864 ac POST DEV PostDev2 Type 11 24-hr 100yr, 24 hr Rainfall=8.90" Prepared by {enter your company name here) Printed 7/16/2020 HvdroCAD® 9.10 s/n 07054 02011 HvdroCAD Software Solutions LLC Paae 17 Summary for Subcatchment 1 S: Offsite Treated Runoff = 2.24 cfs @ 11.96 hrs, Volume= 0.104 af, Depth= 4.14" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 100yr, 24 hr Rainfall=8.90" Area (ac) CN Description 0.300 61 >75% Grass cover, Good, HSG B 0.300 100.00% Pervious Area Tc Length Description Direct Entry, POST DEV PostDev2 Type 1124-hr 100yr, 24 hr Rainfall=8.90" Prepared by {enter your company name here} Printed 7/16/2020 HydroCAD09.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 18 Summary for Subcatchment 2S: Onsite Treated Runoff = 32.68 cfs @ 11.95 hrs, Volume= 1.645 af, Depth= 7.21" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 100yr, 24 hr Rainfall=8.90" Area (ac) CN Description 1.860 98 0.880 61 >75% Grass cover, Good, HSG B 2.740 86 Weighted Average 0.880 32.12% Pervious Area 1.860 67.88% Impervious Area Tc Length Slope Velocity Capacity Description 5.0 Direct Entry, POST DEV PostDev2 Type 1124-hr 100yr, 24 hr Rainfall=8.90" Prepared by {enter your company name here} Printed 7/16/2020 HydroCAD09.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 19 Summary for Subcatchment 3S: Onsite Untreated Runoff = 2.64 cfs @ 11.96 hrs, Volume= 0.122 af, Depth= 4.14" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 100yr, 24 hr Rainfall=8.90" Area (ac) CN Description 0.350 61 >75% Grass cover, Good, HSG B 0.004 98 Paved parking, HSG B 0.354 61 Weighted Average 0.350 98.87% Pervious Area 0.004 1.13% Impervious Area Tc Length Slope Velocity Capacity Description 5.0 Direct Entry, POST DEV PostDev2 Type 1124-hr 100yr, 24 hr Rainfall=8.90" Prepared by (enter your company name here) Printed 7/16/2020 HydroCAD09.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 20 Summary for Subcatchment 4S: Offsite Untreated Runoff = 1.64 cfs @ 11.96 hrs, Volume= 0.076 af, Depth= 4.14" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 100yr, 24 hr Rainfall=8.90" Area (ac) CN Description 0.220 61 >75% Grass cover. Good. HSG B 0.220 100.00% Pervious Area Tc Length Slope Velocity Capacity Description 5.0 Direct Entry, POST DEV PostDev2 Type 1124-hr 100yr, 24 hr Rainfall=8.90" Prepared by (enter your company name here) Printed 7/16/2020 HydroCAD09.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 21 Summary for Pond 5P: StormTech Inflow Area = 3.040 ac, 61.18% Impervious, Inflow Depth = 6.90" for 100yr, 24 hr event Inflow = 34.91 cfs @ 11.95 hrs, Volume= 1.749 of Outflow = 33.58 cfs @ 11.97 hrs, Volume= 1.748 af, Atten= 4%, Lag= 1.3 min Primary = 33.58 cfs @ 11.97 hrs, Volume= 1.748 of Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Peak Elev= 524.97' @ 11.97 hrs Surf.Area= 4,737 sf Storage= 20,778 cf Plug -Flow detention time= 230.8 min calculated for 1.748 of (100% of inflow) Center -of -Mass det. time= 230.4 min ( 1,013.7 - 783.3 ) Volume Invert Avail.Storage Storage Description #1 516.72' 919 cf 36.0" D x 130.01 Pipe Storage S= 0.0098 7' #2 517.50' 11,919 cf 47.46'W x 99.801 x 8.30'H STONE STORAGE 39,313 cf Overall - 9,515 cf Embedded = 29,798 cf x 40.0% Voids #3 519.50' 9,158 cf StormTech MC-4500 x 86 Inside #2 Effective Size= 90.4"W x 60.0"H => 26.46 sf x 4.031 = 106.5 cf Overall Size= 100.0"W x 60.0"H x 4.331 with 0.31' Overlap #4 519.50' 357 cf StormTech MC-4500 Cap x 10 Inside #2 Effective Size= 63.5"W x 59.0"H => 15.25 sf x 2.341 = 35.7 cf Overall Size= 90.2"W x 59.4"H x 2.92'L with 0.58' Overlap 22,353 cf Total Available Storage Device Routina Invert Outlet Devices #1 Primary 516.72' 24.0" Round Culvert L= 77.4' Ke= 0.600 Inlet / Outlet Invert= 516.72' / 516.10' S= 0.0080 '/' Cc= 0.900 n= 0.012 #2 Device 1 516.72' 1.8" Vert. Orifice/Grate-l-YR C= 0.600 #3 Device 1 521.40' 13.0" Vert. Orifice/Grate-10-YR C= 0.600 #4 Primary 523.40' Custom Weir/Orifice, Cv= 2.62 (C= 3.28) Head (feet) 0.00 2.00 Width (feet) 4.00 4.00 Primary OutFlow Max=32.23 cfs @ 11.97 hrs HW=524.91' (Free Discharge) 1- Culvert (Passes 7.89 cfs of 38.03 cfs potential flow) �2=Orifice/Grate-1-YR (Orifice Controls 0.24 cfs @ 13.72 fps) 3=Orifice/Grate-10-YR (Orifice Controls 7.65 cfs @ 8.30 fps) =Custom Weir/Orifice (Weir Controls 24.34 cfs @ 4.03 fps) POST DEV PostDev2 Type ll 24-hr 100yr, 24 hr Rainfall=8.90" Prepared by !enter vour comoanv name here} Printed 7/16/2020 Summary for Link 6L: POA Inflow Area = 3.614 ac, 51.58% Impervious, Inflow Depth > 6.46" for 100yr, 24 hr event Inflow = 37.81 cfs @ 11.97 hrs, Volume= 1.946 of Primary = 37.81 cfs @ 11.97 hrs, Volume= 1.946 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs PROFFIT ROAD TOWNHOMES SOUTH RVPre-Developed Developed 24 Hr 1 vear Storm: developed 1.F. `pre -developed RVPre-Developed Redeveloped developed Qforested RVforested Redeveloped 1.18 0.13 0.117 MaXOdeveloped = 0.42 Cfs 0.384 Qdeveloped = 0.42 Cfs Pre Development Post Development 10 yr 7.20 7.02 PROFFIT ROAD TOWNHOMES SOUTH Time of Concentration Calculations PRE DEVELOPMENT TOC 100 ft Overland Flow 4.10% slope 0.35 C-value 10.9 min Seelye Chart 484.0 ft S.C. Flow 2.25% slope 1.1 fps velocity 7.1 min. NEH Figure 15-4 0.0 ft Channel" 0.0 ft height 0.0 min. Kirpich Chart TOC= 18.0 min. " There is no Channel on site. All ToCs assumed to be 5 minutes. This assumption dictates very conservative design factors. 5.0 MINUTES .1 v Roved y 0 z o .e 300 I— 7 IcZ.7T��: w u_ 200 Soil Poor Grass \SurfaceLLJ Average Grass 6 w U-,5 a x =_ y U Z 90 9 \ a SO Dense 70 Grass z \ N 60 \ J 0 50 V -� 40 x 30 z w J 20 m 35 30 F1 20 w F z_ z z 0.5 w _ w IA o 15 j 2.0 0 / a z o 5.0 z �- 10cr i 20 w 0. w OVERLAND FLOW TIME (Seelye Chart) z 10 U 0 9�w J z 7 V Source: Data Book for Civil Engineers. E.E. Seelye Plate 5-1 1.00 0.90 0.80 0.70 0.60 0.40 0.30 0.20 0.09 0. 0.08 0.07 0 0.06 n 0.05 0.04 0.03 0.02 0.01 0.005 0 2 ci ca v �q 19�i-oo ao c� w v c ctimao d d d d d ddd.: Velocity (ft(s) Proffit Road Townhomes South LD-204 Stormwater Inlet Computations LD-204 Stormwater Inlet Computations Inlets on Grade Only Sag Inlets Only ai a) Q a m Q s c o a) °1 z U" U 0 °? U oa °1 0 r co d U '.' 0 U) N X t6 U U C U C N 9 H L w N U O� N N Z U UT 2 E 9 M Q d U U m m o o_ w m U_ -a x Q 65 z U U m U 0 0 0 (D a (D U) aUi ❑ a 0 0 U o 1 2 1 3 4 5 6 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 (ft) (ac) (in/hr) (cfs) (cfs) (cfs) ( ft/ ft) ( ft/ ft) ( ft/ ft) (ft) (ft) (cfs) (cfs) (ft) (ft) (ft) A10 DI-7 0.42 0.44 0.18 6.5 1.19 - 1.188 0.020 0.04 0.040 0.16 5.08 0.18 4.0 0.73 - 0.731 0.020 0.12 3.95 A8 D1-313 12 0.92 0.80 0.73 6.5 4.77 - 4.767 0.013 0.02 0.030 8.16 0.24 77% 3.69 1.08 0.73 4.0 2.93 - 2.934 0.013 6.81 0.20 91 % 2.68 0.26 A5 DI-313 12 0.94 0.61 0.58 6.5 3.75 1.08 4.822 0.013 0.02 0.020 0.080 0.26 0.50 0.52 7.09 0.58 4.0 2.31 0.26 2.562 0.013 0.080 0.17 0.50 0.34 2.59 A4 DI-3C 12 0.69 0.80 0.55 6.5 3.57 0.00 3.566 0.013 0.026 0.020 0.080 0.30 0.50 0.59 8.76 0.55 1 4.0 2.19 0.00 2.195 0.013 1 1 0.16 0.50 0.32 2.06 PROFFIT ROAD TOWNHOMES SOUTH LD-229 STORM DRAIN DESIGN COMPUTATIONS From To Catch. Runoff Inc Accum ToC 10-Yr 10-Yr Up Dn Pie Inv Pie Pie Velocity Flow time Point Point Area Coef AC AC Intensity Flow cfs invert Invert Length Sloe Diameter Capacity Inc ac min in/hr El El ft % in) (cfs) (ft/s min 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 A10 A9 0.42 0.44 0.18 0.18 5.00 7.10 1.30 529.00 526.50 53.04 4.71% 15 15 7.6 0.12 A9 A8 0.18 5.00 7.10 1 524.50 523.70 77.56 1.03% 1 15 7 1 4.4 0.29 A8 A7 1 0.92 1 0.80 1 0.73 1 0.92 5.00 7.10 6.51 1 523.50 522.50 29.6 1 3.38% 1 15 13 1 10.5 0.05 Note: Detention System Between A7 & A6 A6 A5* 517.30 517.21 34.92 0.26% 36 A5 A4* 517.11 516.87 94.38 0.25% 36 A4 A3 0.79 0.80 0.63 0.00 5.00 7.10 5.86 516.72 516.10 77.42 0.80% 24 6 5.8 0.22 A3 A2 0.00 0.00 5.00 7.10 5.86 515.90 514.00 267.25 0.71 % 24 6 5.7 0.78 A2 Al 0.00 0.00 5.00 7.10 5.86 513.45 511.11 97.26 2.41% 24 8 7.1 0.21 *Pipe Sizing not computed as pipe is used for storage PROFFIT ROAD TOWNHOMES SOUTH LD-347 Hydraulic Grade Line n= 0.012 Junction Loss Outlet Water Inlet Water Structure Surface Surface Number Elev.' Do 00 L0 S, % H, V, H, 0; V; O;V; H; Angle Ho H, 1.3-H, 0.51-1, Final H Elev. Rim. Elev K Height to (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19) (20) (21) (14.5) 0.70 0.66 0.61 0.56 0.5 0.43 0.35 0.3 0.25 0.19 0.13 0.06 Angle Check Rim 5.15 6.13 7.13 7.77 8.21 0.00 4.13 7.09 3.94 0.00 A2 512.71 2.00 5.86 97.3 0.06% 0.06 7.1 0.47 5.86 7.1 41.4 0.02 67 0.47 0.95 0.47 0.529 513.24 518.39 90 OK A3 515.60 2.00 5.86 267.3 0.06% 0.15 5.7 0.07 5.86 5.7 33.4 0.18 7 0.07 0.24 0.121 0.274 515.87 522.00 80 OK A4 518.50 2.00 5.86 77.4 0.06% 0.04 5.8 0.02 5.86 5.8 34.1 0.18 0 0.02 0.20 0.100 0.144 518.64 525.77 70 OK 519.27 3.00 5.86 94.4 0.01 % 0.01 5.8 0.18 5.86 5.8 34.0 0.18 30 0.18 0.37 0.48 0.238 0.244 519.5 60 OK 519.61 3.00 5.86 34.9 0.01 % 0.00 5.8 0.22 5.86 5.8 34.0 0.18 33 0.22 0.45 0.58 0.29 0.294 519.91 50 OK ' A5 AND A6 ARE NOT INCLUDED IN THE HYDRAULICE GRADE DRAWING BECAUSE THEY ARE INSIDE THE DETENTION SYSTEM 40 OK AS 523.50 1.25 6.51 29.6 0.86% 0.26 10.5 0.86 6.51 10.5 68.4 0.60 50 0.86 1.72 2.23 1116 1372 524.87 529.00 30 OK A9 524.70 1.25 1.30 77.6 0.03% 0.03 4.4 0.08 1.30 4.4 5.7 0.11 20 0.08 0.18 -0.24 -0.118 0.208 524.91 532.00 25 OK A10 527.50 1.25 1.30 53.0 0.03% 0.02 7.6 0.54 1.30 7.6 9.8 0.31 61 0.54 1.08 -1.41 0.54 0.560 528.06 532.00 20 OK 15 OK 'Outlet WSE is listed as the greater of either the calculated tailwater or the invert out. 10 5 0.03 0 Estimated to be the same as the outflow from Cl for this submittal. 2 Estimated to be the same as the outflow from D1 for this submittal. Water Quality Calculations: Pre -Development VRRM Landuse Map Post -Development VRRM Landuse Map VRRM Redevelopment Spreadsheets PRE -DEVELOPMENT VRRM LANDUSE MAP J � �� I[ ALL HSG B i I I I O O O❑ , . T I I i SFNITARY EASEIAENT W D 5XI PG J I D' 5PNITARY EASg1ENT -_B SJM PG 3=6 I_ SVy I T/� 2.72 AC TURF ---TIv1P-32-25R__�•• (NO HATCH) •�� ••�' ��., 0.37 AC 0.2E AC WOODS •�` � 1 IMPERVIOUS 7LIMITS OF DISTURBANCE `. • •� USED AS BOUNDARY FOR WATER QUALITY�i ••� IMPROVEMENTS AREA = 3.34 AC III 0111110111111 III 1 1 1 1 1 1 1 \ 1 1 Z i 60 0 60 120 SO Scale: 1 "=60' POST -DEVELOPMENT VRRM LANDUSE MAP Scale: 1 "=60' DEq Virginia Runoff Reduction Method Re -Development Compliance Spreadsheet - Version 3.0 112011 BMP Standards and Specifications 02013 Draft BMP Standards and Specifications �- Project Name: Proffit South ® datainput cells Date: 7/8/2020 constant values Linear Development Project? No calculation cells Site Information Post -Development Project (Treatment Volume and Loads) Enter Total Disturbed Area (acres) 3.34 Check. BMP Desi n Spec' fcatians List: 2013 Draft Stds & Specs Linearproject? No ® Land cover areas entered correctly? ✓ F ® Total disturbed area entered? ✓ Pre-ReDevelopment Land Cover (acres) A Soils BSoils7SoilsDTotals Forest/Open Space (acres) - undisturbetl forest/open space 0.370.37 Manned Tuff lacres)-disturbed, graded for 2J2 yards or other brim be mowed/managed 2.72 Impervious Caver(acres) 02S 0.25 3.34 Post -Development Land Cover (acres) A soils BSoils CSoils DSoils Totals Forest/Open Space (acres) -- undisturbed, 0.00 space protected forest/openreforested land Manned Tuff (acres) graded for 1'� yards or other turf t0 be mowed/mana ed 1.40 Impervious Caver(acres) 1.90 1.90 Area Check OK. OK. OK. OK. 3.34 Constants Runoff Coefficients Rv Annual Rainfall (inches) 43 ASoils BSoils CSoils DSoils Target Rainfall Ecent(inches) 1.00 Forest/Open Space 0.02 0.03 0.00 0.05 Total Phosphorus (TP) EMC(mg/L) 0.26 ManagelTurf OAS 0.20 0.22 0.25 Total Nitrogen (TN) EMC(mg/L) 1.86 Impervious Cower 0.95 0.95 0.95 0.95 Target TP Load(lb/acre/yr) OA1 Pj(unitless correction factor) 0.90 LAND COVER SUMMARY -- PRE-REDEVELOPMENTr COVER SUMMARY POST DEVELOPMENT Land Cower SummorePre Lord Cover Summary-Pbst(Finnl) Land Cover Summarynaost Lomf Cover Summary -Post Pre-ReDecelopment Listed Adjusted' Post Rebev.&New Impervious PortAeDecelapment Post -Development New Impervious Forest/Open Space COcer(acres( 0.37 0.00 Forest/Open Space Forest/Open 0.00 Forrst/Open Space 0.00 Cower (acres) Weighted Rv(foresu 0.03 0.00 Weighted Rv(finesq 0.00 Weighted RvOorest) 0.00 %Forest 11% 0% %Forest 0% %Forest 0% Managed Turf Cover (acres) 2.72 144 Managed Turf Cover 149 Manegetl TurfCover 144 (acres) (acres) Weighted Rv(turf) 0.20 0.20 Weighted Far (turf) 0.20 Weighted RV Joel) 0.20 %Managed Turf 81% 85% %Manned Turf 43% %Managed Tuff 85% Impervious tower (acres) 0.25 0.25 lmpe(ares� 1.90 ReDec 025 Newlm'crvio s Geer 1.65 cover (acres)us Rv(imperaceas) 0.95 0.95 Rv(imperviaus) 0.95 W(imperviousl 0.95 Rv(impervious) 0.95 %Impervious 7% 15% %Impervious 57% %Impervious 15% Total She Area (acres) 3.34 1.69 Final Site Area (so.) 3.34 Total ReOev. She Area 169 (acres) She RV 0.24 0.31 Final Post Dee She Re 0.63 ReDev She IN 031 Treatment Volume and Nutrient Load Treatment Volume and Nutrient Load Port -Development Final pme Post-ReDevelopment Pre-ReOewelopmeM Treatment Volume 0.0661 0.0438 Development O.1144 Treabnece Volume 0.0438 Trentment Volunw 0.1306 (acre-ft) TrealmentVoluna, larre-kl (acre-k) (acre -fit) Port -Development Final Pan- postReDeeelopment Pre-ReOewelopment Treatment Volume 2,87J 1,908 Development 7,598 Treabnad Volume 1,908 Treatment Volume (cubic 5,690 (cubic feet) TrentmentVolume (arbk feet) feet) (cubic feet) PostAelievelopment Post -Development TP Pre-ReDevelopment TP Load Final Post- 1.91 1.20 Development TP Load 4.77 Wad (TP' 3.58 (lb/yr) (Ib/yr) (lb/yr)a Wad(lb/yr) FmReOevelopmen[lPLoatl peracre Final Part-0evelopment TP Post-ReDevelopment 1P (pmerelP am 0J1 Load per acre 1.49 Lord pe,art. (lb/ave/yr) (lb/acre/yr) Baseline TP Loatl (lb/yr) Maa Reduction Required (OAl lbs/ave/yr applied to pmreaevelopment area excluding pervious 0.69 (Below Pre M% land Proposed for new impervious cover) ReDevelopment Load) 'Adjusted Land Cower Summary: TP Load Reduction TP Load Reduction Pre ReDevelopment land cover minus pervious land rover Oorest/open spare or Required for 0.24 , Required for New 2.90 staged far aneogl Pmpasetlfarnew impervious rover. Redeveloped Area Impervious Area (lb/yr) (hope Adjusted total acreage is consistent with Past-RagavelapmeM acreage(minus acreage of an. impervious rover). Column I shawl Toad reduction rer urfementfor new impervious cover (based on new development bad limit, 0.41 f&A ne/ysar). Post -Development TP load Reduction Required (Ib/yr) 3.14 Nitrogen Loads (Informational Purposes Only) Final Pon -Development TN Load Pre-ReDewslopment TN Wad(lb/yr) 12.93 (Post-ReDerelopmett&New 34.15 Impervious) (lb/yr) Drainage Area A Drainage Area A Land Cover (acres) Land Cover A Soils BSoils CSoils DSoils Totals Rv Forest/Open Space (acres) 0.00 0.00 Managed Turf(acres) 0.88 0.88 0.20 Impervious Cover (acres) 1.86 1.86 0.95 Total Phosphorus Available for Removal in D.A. A (lb/yr) 4.43 Total 2.74 Post Development Treatment Volume in D.A. A (ft')i 7,053 Stormwater Best Management Practices (RR= Runoff Reduction) Runoff Managed Turf Impervious Volume from Runoff Remaining Total BMP Phosphorus Phosphorus Untreated Phosphorus Remaining Practice Reduction Credit Area Cover Credit Upstream Reduction Runoff Treatment Removal Load from Phosphorus Removed By Phosphoro Credit (%) (acres) Area (acres) practice (kal (ft) Volume fts ( ) Volume ka ( 1 Efficiency W (%) Upstream Load to Practice (lb) s Load (lb) 14. Manufactured Treatment Practices (lb) Practice (lb) 14.a. Manufactured Treatment Device- 0 0.88 1.86 0 0 7,053 7,053 40 0.00 4.43 1.77 2.66 Hydrodynamic TOTAL IMPERVIOUS COVER TREATED(ac) 1.86 AREACHECK:OK. TOTAL MANAGED TURF AREA TREATED(ac) 0.88 AREACHECK:OK. TOTAL PHOSPHORUS REMOVAL REQUIRED ON SITE (lb/yr) 3.14 TOTAL PHOSPHORUS AVAILABLE FOR REMOVAL IN D.A. A (lb/yr) 4.43 TOTAL PHOSPHORUS REMOVED WITHOUT RUNOFF REDUCTION PRACTICES IN D.A. A (lb/yr) 1.77 TOTAL PHOSPHORUS REMOVED WITH RUNOFF REDUCTION PRACTICES IN D.A. A (lb/yr) 0.00 TOTAL PHOSPHORUS LOAD REDUCTION ACHIEVED IN D.A. A (lb/yr) 1.77 TOTAL PHOSPHORUS REMAINING AFTER APPLYING BMP LOAD REDUCTIONS IN D.A. A (lb/yr) 2.66 SEE WATER QUALITY COMPLIANCE TAB FOR SITE COMPLIANCE CALCULATIONS NITROGEN REMOVED WITH RUNOFF REDUCTION PRACTICES IN D.A. A (Ib/yr) 0.00 NITROGEN REMOVED WITHOUT RUNOFF REDUCTION PRACTICES IN D.A. A (Ib/yr) 0.00 TOTAL NITROGEN REMOVED IN D.A. A (Ib/yr) 0.00 Site Results (Water Quality Compliance) Area Checks D.A. A D.A. B D.A. C D.A. D D.A. E AREA CHECK FOREST/OPEN SPACE (ac) 0.00 0.00 0.00 OK. IMPERVIOUS COVER (ac) 1.86 0.00 0.00 0.00 OK. IMPERVIOUS COVER TREATED (ac) 1.86 0.00 E0.00 0.00 T MANAGED TURF AREA (ac) 0.88 0.00 0.00 MANAGED TURF AREA TREATED (ac) 0.88 0.00 0.00 0.00 OK. AREA CHECK Site Treatment Volume (ft3) 7,s96 Runoff Reduction Volume and TP By Drainage Area D.A. A D.A. B D.A. C D.A. D D.A. E TOTAL RUNOFF REDUCTION VOLUME ACHIEVED (ft) 0 1 0 0 0 0 TP LOAD AVAILABLE FOR REMOVAL (Ib/yr) 4.43 0.00 0.00 0.00 0.00 4.43 TP LOAD REDUCTION ACHIEVED (Ib/yr) 1.77 0.00 0.00 0.00 0.00 1.77 TP LOAD REMAINING (Ib/yr) 2.66 0.00 0.00 0.00 0.00 2.66 NITROGEN LOAD REDUCTION ACHIEVED (Ib/yr) D.00 0.00 0.00 0.00 0.00 0.00 Total Phosphorus FINAL POST-DEVELOPMENTTP LOAD(Ib/yr) 4.77 TP LOAD REDUCTION REQUIRED (Ib/yr) 3.14 TP LOAD REDUCTION ACHIEVED (Ib/yr) 1.77 TP LOAD REMAINING (Ib/yr): 3.00 REMAINING TP LOAD REDUCTION REQUIRED (Ib/yr): 1.37 Total Nitrogen (For Information Purposes) POST -DEVELOPMENT LOAD(Ib/yr) 1 34.15 NITROGEN LOAD REDUCTION ACHIEVED (Ib/yr) 0.00 REMAINING POST -DEVELOPMENT NITROGEN LOAD (Ib/yr) 34.15 Independent Reports: Excerpt from NRCS Soils Report NOAA Precipitation Report USDA United States Department of Agriculture MRCS Natural Resources Conservation Service A product of the National Cooperative Soil Survey, a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local participants Custom Soil Resource Report for Albemarle County, Virginia November 1 2019 Preface Soil surveys contain information that affects land use planning in survey areas. They highlight soil limitations that affect various land uses and provide information about the properties of the soils in the survey areas. Soil surveys are designed for many different users, including farmers, ranchers, foresters, agronomists, urban planners, community officials, engineers, developers, builders, and home buyers. Also, conservationists, teachers, students, and specialists in recreation, waste disposal, and pollution control can use the surveys to help them understand, protect, or enhance the environment. Various land use regulations of Federal, State, and local governments may impose special restrictions on land use or land treatment. Soil surveys identify soil properties that are used in making various land use or land treatment decisions. The information is intended to help the land users identify and reduce the effects of soil limitations on various land uses. The landowner or user is responsible for identifying and complying with existing laws and regulations. Although soil survey information can be used for general farm, local, and wider area planning, onsite investigation is needed to supplement this information in some cases. Examples include soil quality assessments (http://www.nrGs.usda.govtwps/ portal/nres/main/soils/healthn and certain conservation and engineering applications. For more detailed information, contact your local USDA Service Center (https:Hoffices.sc.egov.usda.gov/locator/app?agency=nres) or your NRCS State Soil Scientist (http://www.nrGs.usda.govtwps/portal/nres/detail/soils/contactus/? cid=nres 142p2_053951). Great differences in soil properties can occur within short distances. Some soils are seasonally wet or subject to flooding. Some are too unstable to be used as a foundation for buildings or roads. Clayey or wet soils are poorly suited to use as septic tank absorption fields. A high water table makes a soil poorly suited to basements or underground installations. The National Cooperative Soil Survey is a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local agencies. The Natural Resources Conservation Service (NRCS) has leadership for the Federal part of the National Cooperative Soil Survey. Information about soils is updated periodically. Updated information is available through the NRCS Web Soil Survey, the site for official soil survey information. The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or a part of an individual's income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write to USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410 or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provider and employer. 3 Contents Preface................................................................ SoilMap.............................................................. SoilMap........................................................... Legend............................................................. Map Unit Legend .............................................. Map Unit Descriptions ...................................... Albemarle County, Virginia ........................... 27B—Elioak loam, 2 to 7 percent slopes.. .2 .5 ..6 ..7 .8 .8 10 10 C! Soil Map The soil map section includes the soil map for the defined area of interest, a list of soil map units on the map and extent of each map unit, and cartographic symbols displayed on the map. Also presented are various metadata about data used to produce the map, and a description of each soil map unit. M' 7W N 3 TWN Custom Soil Resource Report N Soil Map N N fn T25010 7250G0 725= 72510D 7251M 72510D 725190 DI 3 3 q iF p Map Smie:1:1,270 rn5' Ded m A pDbat(8.x 1175bBt q N Meters 0 15 30 W 9D A0 50 700 Z00 3r Mapproedb:WebMammr Cmc rdnz�:WGSB4 Edgdrs:UTMZm17NWGS84 6 A n Y I I 3 7'WN MAPLEGEND Area of Interest (AOQ O Area of Interest (AOI) Solis Soil Map Unit Polygons N Soil Map Unit Lines Soil Map Unit Points Special Point Features V Blowout ® Borrow Pit Clay Spot O Closed Depression Gravel Pit Gravelly Spot O Landfill A. Lava Flow Marsh or swamp Mine or Quarry O Miscellaneous Water O Perennial Water y Rock Outcrop + Saline Spot Sandy Spot Severely Eroded Spot Q Sinkhole Slide or Slip J, Sodic Spot Custom Soil Resource Report MAP INFORMATION g Spoil Area The soil surveys that comprise your AOI were mapped at 1:15,800. o Stony Spot W Very Stony Spot Warning: Soil Map may not be valid at this scale. wet Spot Enlargement of maps beyond the scale of mapping can cause Other misunderstanding of the detail of mapping and accuracy of soil Special Line Features line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed Water Features scale. Streams and Canals Transportation Please rely on the bar scale on each map sheet for map �..ry Rails measurements. N Interstate Highways Source of Map: Natural Resources Conservation Service ti US Routes Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Major Roads Local Roads Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts Background distance and area. A projection that preserves area, such as the . Aerial Photography Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Albemarle County, Virginia Survey Area Data: Version 13, Sep 17, 2019 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: May 20, 2019—Aug 1, 2019 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. V1 Custom Soil Resource Report Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 27B Elioak loam, 2 to 7 percent slopes 4.0 100.0% Totals for Area of Interest 4.0 100.0% Map Unit Descriptions The map units delineated on the detailed soil maps in a soil survey represent the soils or miscellaneous areas in the survey area. The map unit descriptions, along with the maps, can be used to determine the composition and properties of a unit. A map unit delineation on a soil map represents an area dominated by one or more major kinds of soil or miscellaneous areas. A map unit is identified and named according to the taxonomic classification of the dominant soils. Within a taxonomic class there are precisely defined limits for the properties of the soils. On the landscape, however, the soils are natural phenomena, and they have the characteristic variability of all natural phenomena. Thus, the range of some observed properties may extend beyond the limits defined for a taxonomic Gass. Areas of soils of a single taxonomic class rarely, if ever, can be mapped without including areas of other taxonomic classes. Consequently, every map unit is made up of the soils or miscellaneous areas for which it is named and some minor components that belong to taxonomic classes other than those of the major soils. Most minor soils have properties similar to those of the dominant soil or soils in the map unit, and thus they do not affect use and management. These are called noncentrasting, or similar, components. They may or may not be mentioned in a particular map unit description. Other minor components, however, have properties and behavioral characteristics divergent enough to affect use or to require different management. These are called contrasting, or dissimilar, components. They generally are in small areas and could not be mapped separately because of the scale used. Some small areas of strongly contrasting soils or miscellaneous areas are identified by a special symbol on the maps. If included in the database for a given area, the contrasting minor components are identified in the map unit descriptions along with some characteristics of each. A few areas of minor components may not have been observed, and consequently they are not mentioned in the descriptions, especially where the pattern was so complex that it was impractical to make enough observations to identify all the soils and miscellaneous areas on the landscape. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The objective of mapping is not to delineate pure taxonomic classes but rather to separate the landscape into landforms or landform segments that have similar use and management requirements. The delineation of such segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, however, onsite investigation is needed to define and locate the soils and miscellaneous areas. R9 Custom Soil Resource Report An identifying symbol precedes the map unit name in the map unit descriptions. Each description includes general facts about the unit and gives important soil properties and qualities. Soils that have profiles that are almost alike make up a soil series. Except for differences in texture of the surface layer, all the soils of a series have major horizons that are similar in composition, thickness, and arrangement. Soils of one series can differ in texture of the surface layer, slope, stoniness, salinity, degree of erosion, and other characteristics that affect their use. On the basis of such differences, a soil series is divided into soil phases. Most of the areas shown on the detailed soil maps are phases of soil series. The name of a soil phase commonly indicates a feature that affects use or management. For example, Alpha silt loam, 0 to 2 percent slopes, is a phase of the Alpha series. Some map units are made up of two or more major soils or miscellaneous areas. These map units are complexes, associations, or undifferentiated groups. A complex consists of two or more soils or miscellaneous areas in such an intricate pattern or in such small areas that they cannot be shown separately on the maps. The pattern and proportion of the soils or miscellaneous areas are somewhat similar in all areas. Alpha -Beta complex, 0 to 6 percent slopes, is an example. An association is made up of two or more geographically associated soils or miscellaneous areas that are shown as one unit on the maps. Because of present or anticipated uses of the map units in the survey area, it was not considered practical or necessary to map the soils or miscellaneous areas separately. The pattern and relative proportion of the soils or miscellaneous areas are somewhat similar. Alpha -Beta association, 0 to 2 percent slopes, is an example. An undifferentiated group is made up of two or more soils or miscellaneous areas that could be mapped individually but are mapped as one unit because similar interpretations can be made for use and management. The pattern and proportion of the soils or miscellaneous areas in a mapped area are not uniform. An area can be made up of only one of the major soils or miscellaneous areas, or it can be made up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example. Some surveys include miscellaneous areas. Such areas have little or no soil material and support little or no vegetation. Rock outcrop is an example. W Custom Soil Resource Report Albemarle County, Virginia 2713—Elioak loam, 2 to 7 percent slopes Map Unit Setting National map unit symbol: kb8y 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 Elioak and similar soils: 80 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Elioak Setting Landform: Hillslopes Landform position (two-dimensional): Summit Landform position (three-dimensional): Interfluve Down -slope shape: Convex Across -slope shape: Convex Parent material: Residuum weathered from mica schist Typical profile H1 - 0 to 8 inches: loam H2 - 8 to 39 inches: silty clay H3 - 39 to 79 inches: silt loam 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 (0.20 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: Moderate (about 6.6 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 2e Hydrologic Soil Group: B Hydric soil rating: No 10 11/112019 Precipitation Frequency Data Server NOAA Atlas 14, Volume 2, Version 3 Location name: Charlottesville, Virginia, USA* E ,.. Latitude: 38.1309°, Longitude:-78.4283° FW�WI Elevation: 538.71 ft** " source: ESRI Maps "" source: USGS POINT PRECIPITATION FREQUENCY ESTIMATES G.M. Bonin, D. Martin, B. Lin, T. Parzybok, M.Yekta, and D. Riley NOAA, National Weather Service, Silver Spring, Maryland PF tabular I PF graphical I Maps & aerials PF tabular PDS-based point precipitation frequency estimates with 90% confidence intervals (in inches)1 Average recurrence interval (years) Duration 7 2 5 10 25 50 1 100 00 200 500 1000 0.349 F 0.416 F 0.489 F 0.551 F 0.621 F 0.677 F 0.729 F 0.778 F 0.839 F 0.889 5-min (0 315-0.386) (0.376-0.461) (0.441-0.541) (0.495-0.609) (0.556-0.685) (0.603-0.745) (0.645-0.802) (0.694-0.858) (0.730-0.928) (0.78-0.986) 10-min (g_503-0617) (0.602-0 38) (0.707-0866) (0.79-0.974) (0.886---11.09) (0.960-18.19) (1.03127) (1.09-21336) (1. 5-3L47) (1214.55) 0.697 0.837 0.991 1.11 1.25 1.36 1.46 1.56 1.67 1.76 15-min (0.629-0.772) (0.756-0.928) (0.894-1.10) 1 (1.00-1.23) 1 (1.12-1.38) 1 (1.22-1.50) 1 (1.30-1.61) 1 (1.37-1.72) 1 (1.45-1.85) 1 (1.51-1.95) 0.955 1.16 1.41 1.61 1.86 2.06 2.24 2.42 2.66 2.85 30-min (0.862-1.06) 1 (1.05-1.28) 1 (1.27-1.56) 1 (1.45-1.79) 1 (1.66-2.05) 1 (1.83-2.26) 1 (1.99-2.47) 1 (2.13-2.67) 1 (2.31-2.94) (2.45-3.16) 1.19 1.45 1.81 2.10 2.48 2.78 3.09 3.40 3.82 4.15 60-min (1.08-1.32) 1 (1.31-1.61) 1 (1.63-2.00) 1 (1.89-2.32) 1 (2.22-2.73) 1 (2.48-3.07) 1 (2.74-3.40) 1 (2.99-3.75) 1 (3.32-4.22) 1 (3.58-4.61) 1.43 1.74 2.18 2.56 3.06 3.47 3.90 4.35 4.99 5.52 2-hr (1.27-1.62) 1 (1.54-1.97) 1 (1.93-2.46) 1 (2.27-2.88) 1 (2.69-3.43) 1 (3.04-3.90) 1 (3.39-4.38) 1 (3.75-4.89) 1 (4.25-5.61) 1 (4.8-6.23) 1.57 1.90 2.38 2.79 3.33 3.79 4.27 4.77 5.47 6.07 3-hr (1.38-1.79) 1 (1.67-2.17) 1 (2.09-2.71) 1 (2.45-3.18) 1 (2.91-3.79) 1 (3.29-4.30) 1 (3.68-4.84) 1 (4.07-5.41) 1 (4.61-6.22) 1 (5.D6-6.91) 1.99 2.41 2.99 3.52 4.23 4.86 5.52 6.23 7.26 8.17 6-hr (1.77-2.26) 1 (2.13-2.74) 1 (2.64-3.39) (3.09-3.99) (3.69-4.80) (4.21-5.49) (4.73-6.24) (5.29-7.05) (6.07-8.22) (6.73-9.26) 2.49 3.01 3.75 4.44 5.40 6.26 7.20 8.23 9.76 11.1 12-hr (2.21-2.85) 1 (2.66-3.44) 1 (3.31-4.29) (3.90-5.06) (4.70-6.14) (5.40-7.11) (6.13-8.17) (6.91-9.33) (8.04-11.1) (9.02-12.7) 2997 3.60 4.60 5.43 6.67 7.73 8.90 10.2 12.1 13.8 24-hr (2.67-3.35) (3.23-4.05) (4.11-5.17) (4.84-6.10) (5.91-7.47) (6.80-8.64) (7.76-9.93) (8.79-11.3) (10.3-13.5) (11.5-15.3) 2-day (3. 6391) (3. 3-4.74) (4.85 6002) (5. 8--374.07) (6.86 8?57) (7. 3 9684) (8.86- 12) (9.97- 2.7) (115315.0) (12.t8-16.9) 3.73 4.52 5.74 6.74 8.20 9.41 10.7 12.2 14.2 16.0 3-day (3.39-4.14) 1 (4.10-5.01) 1 (5.20-6.36) 1 (6.09-7.46) 1 (7.36-9.06) 1 (8.40-10.4) 1 (9.50-11.9) 1 (10.7-13.4) 1 (12.4-15.8) 1 (13.7-17.8) 3.96 4.79 6.08 7.15 8.68 9.97 11.4 12.9 15.0 16.9 4-day (3.62-4.37) 1 (4.38-5.29) 1 (5.55-6.71) 1 (6.50-7.86) 1 (7.86-9.54) 1 (8.97-11.0) 1 (10.1-12.5) 1 (11.4-14.1) 1 (13.2-16.6) 1 (14.6-18.7) 4.60 5.54 6.92 8.06 9.69 11.0 12.5 14.1 16.3 18.2 7-day (4.21-5.05) 1 (5.07-6.07) 1 (6.33-7.59) 1 (7.35-8.83) 1 (8.79-10.6) 1 (9.97-12.1) 1 (11.2-13.7) 1 (12.5-15.4) 1 (14.3-17.9) 1 (15.8-20.0) 5.22 6.27 7.73 B.93 10.6 12.0 13.4 15.0 17.1 18.9 10day (4.80-5.68) (5.77-6.81) (7.11-8.40) (8.19-9.69) (9.69-11.5) (10.9-13.0) (12.1-14.6) (13.4-16.3) (15.2-18.7) (16.6-20.7) 6.86 8.19 9.89 11.2 13.0 14.5 15.9 17.4 19.4 21.0 20-0ay P� (6.41-7.38) (7.65-8.80) (9.22-10.6) (10.4-12.0) (12.1-14.0) (13.4-15.5) (14.7-17.1) (15.9-18.7) (17.7-20.9) (19.0-22.7) 8.42 9.98 11.8 13.2 15.0 16.4 17.7 19.0 20.8 22.1 30rlay (7.91-8.99) 1 (9.38-10.7) 1 (11.1-12.6) 1 (12.4-14.1) 1 (14.0-16.0) 1 (15.3-17.5) 1 (16.5-18.9) 1 (17.6-20.3) 1 (19.1-22.3) 1 (20.2-23.7) 22.4 IF 45tlay (9.91---11.2) (11.172--13.2) (13.14 5.4) (15..1---17.0) (17.10-19.2) (18.t4- 0.8) (196�2.3) (20.9- 3.8) (2244 5.8) (2325-27.2) 12.4 14.5 16.8 18.4 20.6 22.1 23.6 25.0 26.8 28.1 BOrlay (11.7-13.1) (13.7-15.4) (15.8-17.7) (17.4-19.5) (19.4-21.7) (20.8-23.4) (22.2-25.0) (23.5-26.5) (25.0-28.4) (26.1-29.9) 1 Precipitation frequency (PF) estimates in this table are based on frequency analysis of partial duration series (PDS). Numbers in parenthesis are PF estimates at lower and upper bounds of the 90% confidence interval. The probability that precipitation frequency estimates (for a given duration and average recurrence interval) will be greater than the upper bound (or less than the lower bound) is 5%. Estimates at upper bounds are not checked against probable maximum precipitation (PMP) estimates and may be higher than currently valid PMP values. Please refer to NOAA Atlas 14 document for more information. Back to Top hftps://hdsc.nws.noaa.gov/hdsolpfds/pfds_Printpage.html?lat=38.1309&Ion=-78.4283&data=depth&units=english&series=pds 1/4