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HomeMy WebLinkAboutWPO202200013 Calculations 2022-03-24TJACH PREMIER CIRCLE - WPO MASTER PLAN ALBEMARLE COUNTY, VIRGINIA DESIGN CALCULATIONS & NARRATIVE WPO 2022-XXXX MARCH 21, 2022 s TIMMONS GROUP YOUR VISION ACHIEVED THROUGH OURS. Prepared by: Jonathan Showalter, PE Timmons Group 608 Preston Avenue, Suite 200 Charlottesville, VA 22903 434.327.1681 Table of Contents Section Title Project Narrative 2.1 Overall Stormwater Management Master Plan Routing Calculations 2.2 Phase 1 Stormwater Management Master Plan Routing Calculations 2.3 LD-204 Inlet Calculations — Phase 1 2.4 LD-229 Pipe Calculations — Phase 1 3.1 Virginia Runoff Reduction Method Worksheet Summary — Overall Stormwater Management Master Plan 3.2 Virginia Runoff Reduction Method Worksheet Summary — Phase 1 Plan Project Narrative: This project included the removal of existing hotel buildings and associated hardscapes and utilities in order to construct two buildings developed by Virginia Supportive Housing (VSH) (Phase 1) and Piedmont Housing Alliance (PHA) (Phase 2), and a commercial building to be developed by another developer (Phase 3). This work will be completed in three phases. The first phase will remove one of the existing hotels and include the construction of the PHA building located in the middle of the parcel. Phase 2 will include the removal of the northern hotel building and include the construction of the VSH building. Phase 3 will include the removal of the southern hotel building and include the construction of the commercial building. This narrative includes stormwater calculations for the overall master plan of the site as well as phase 1. Phase 2 and 3 will have their own VMSP/ WPO submitted for review and approval before construction. The overall anticipated limit of disturbance is 3.68 acres and the limits of disturbance for phase 1 is 1.75 acres. Water Ouality: The current site has four buildings with associated parking. For the master plan, 3.68 acres of disturbance was analyzed for water quality and will require 1.14 lb./year to be treated. This requirement is anticipated to be met through the purchase of offsite nutrient credits from a DEQ approved credit bank. For Phase 1, 1.75 acres of disturbance was analyzed for water quality. Due to the decrease in impervious area in phase 1, no credits will be required. Water Ouantity The existing site is mostly impervious with buildings and parking lots. The Master Plan proposed development will have similar impervious cover. The majority of the site's runoff in the existing conditions is captured in an existing storm sewer system and conveyed to an existing stormwater facility located on the northeast comer of the site. In the final condition of the master plan, the existing stormwater facility will be removed. To satisfy the 9VAC-970-66.B stormwater requirement for channel protection, the energy balance equation was used. Due the decrease in impervious area, phase three will not require any detention, therefore energy balance for the overall site will be satisfied by an underground detention pipe that captures runoff from phase 1 and 2 and will be installed during phase 2. To satisfy 9VAC-970-66.0 stormwater requirement for flood protection, the post developed 10-year storm was detained to be less than pre -developed 10-year storm. In the final phase 1 condition, the existing stormwater facility will remain and all runoff from the site will be directed to the facility. To satisfy the 9VAC-970-66.B stormwater requirement for channel protection, the energy balance equation was applied to the limits of disturbance for phase 1. Based on the equation, no detention is required. To satisfy the 9VAC-970-66.0 stormwater requirement for flood protection, the post developed 10-year flow is less than the pre -developed 10-year flow for phase 1. 8S Preto P nd 9S A Pr Bypass Ex. Pon\ 24L AP Pre Subcat Reach Aon Llnk 15S 13S O UGD BYPASS OST .2 �UGD 21L AP post OVERALL STORMWATER MANAGEMENT MASTER PLAN ROUTING CALCULATIONS Prepared by Timmons Group Printed 3/21/2022 Project Notes Rainfall events imported from "NRCS-Rain.txt" for 8701 VA Albemarle Zone-1 Rainfall events imported from "NRCS-Rain.txt" for 8701 VA Albemarle Zone-1 OVERALL STORMWATER MANAGEMENT MASTER PLAN ROUTING CALCULATIONS Prepared by Timmons Group Printed 3/21/2022 Area Listing (all nodes) Area CN Description (acres) (subcatchment-numbers) 4.790 98 (8S, 9S, 13S, 15S) 2.560 61 >75% Grass cover, Good, HSG B (8S, 9S, 13S, 15S) 7.350 85 TOTAL AREA OVERALL STORMWATER MANAGEMENT MASTER PLAN ROUTING CALCULATIONS Prepared by Timmons Group Printed 3/21/2022 Soil Listing (all nodes) Area Soil Subcatchment (acres) Group Numbers 0.000 HSG A 2.560 HSG B 8S, 9S, 13S, 15S 0.000 HSG C 0.000 HSG D 4.790 Other 8S, 9S, 13S, 15S 7.350 TOTAL AREA OVERALL STORMWATER MANAGEMENT MASTER PLAN ROUTING CALCULATIONS Prepared by Timmons Group Printed 3/21/2022 Ground Covers (all nodes) HSG-A HSG-B HSG-C HSG-D Other Total Ground Subcatchment (acres) (acres) (acres) (acres) (acres) (acres) Cover Numbers 0.000 0.000 0.000 0.000 4.790 4.790 8S, 9S, 13S, 15S 0.000 2.560 0.000 0.000 0.000 2.560 >75% Grass cover, Good 8S, 9S, 13S, 15S 0.000 2.560 0.000 0.000 4.790 7.350 TOTAL AREA OVERALL STORMWATER MANAGEMENT MASTER PLAN ROUTING CALCULATIONS Prepared by Timmons Group Printed 3/21/2022 Pipe Listing (all nodes) Line# Node In -Invert Out -Invert Length Slope n Width Diam/Height Inside -Fill Number (feet) (feet) (feet) (ft/ft) (inches) (inches) (inches) 1 7P 468.36 467.66 5.0 0.1400 0.020 0.0 18.0 0.0 2 20P 100.00 98.00 25.0 0.0800 0.012 0.0 18.0 0.0 OVERALL STORMWATER MANAGEMENT MASTERVOAA 24-hrD 100-Year Rainfall=9.14" Prepared by Timmons Group Printed 3/21/2022 HydroCAD® 10.10-7a s/n 08663 © 2021 HydroCAD Software Solutions LLC Page 7 Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment8S: Pre to Pond Runoff Area=3.340 ac 71.56% Impervious Runoff Depth>7.03" Tc=6.0 min CN=87 Runoff=26.55 cfs 1.957 of Subcatchment9S: Pre Bypass Runoff Area=0.330 ac 3.03% Impervious Runoff Depth>4.07" Tc=6.0 min CN=62 Runoff=1.68 cfs 0.112 of Subcatchment13S: BY PASS POST Runoff Area=1.420 ac 54.93% Impervious Runoff Depth>6.35" Tc=6.0 min CN=81 Runoff=10.54 cfs 0.752 of Subcatchment15S: TO UGD Runoff Area=2.260 ac 71.24% Impervious Runoff Depth>7.03" Tc=6.0 min CN=87 Runoff=17.96 cfs 1.324 of Pond 7P: Ex. Pond Peak Elev=471.41' Storage=2,658 cf Inflow=26.55 cfs 1.957 of Outflow=21.90 cfs 1.957 of Pond 20P: UGD Peak Elev=105.55' Storage=0.065 of Inflow=17.96 cfs 1.324 of Outflow=18.67 cfs 1.323 of Link 21 L: AP post Inflow=28.98 cfs 2.074 of Primary=28.98 cfs 2.074 of Link 24L: AP Pre Inflow=23.41 cfs 2.069 of Primary=23.41 cfs 2.069 of Total Runoff Area = 7.350 ac Runoff Volume = 4.145 of Average Runoff Depth = 6.77" 34.83% Pervious = 2.560 ac 65.17% Impervious = 4.790 ac OVERALL STORMWATER MANAGEMENT MASTERVOAA 24-hrD 100-Year Rainfall=9.14" Prepared by Timmons Group Printed 3/21/2022 Summary for Subcatchment 8S: Pre to Pond Runoff = 26.55 cfs @ 12.13 hrs, Volume= 1.957 af, Depth> 7.03" Routed to Pond 7P : Ex. Pond Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hrD 100-Year Rainfall=9.14" Area (ac) CN Description 2.390 98 0.950 61 >75% Grass cover, Good, HSG B 3.340 87 Weighted Average 0.950 28.44% Pervious Area 2.390 71.56% Impervious Area Tc Length Capacity Description 6.0 Direct Entry, Subcatchment 8S: Pre to Pond Hydrograph I---_----f--------+---- 28 2555 cfa 26 ---' -- O A 2'4-hr D - - 24 -- 400 Year Rairifallr9.44"-- 22 --- RunbfFArrea=3.-340 ac- 20 18 Runoff Volume=1.957'aT- V 16 Runoff D"th;�,7.0_ 4 -- j--- --- T,c=6'60-MIM- L -~ 12 i___ __ 10 f N=,67 a 6 4 2 0. 5 6 10 Time (hours) 15 16 17 18 19 20 G Runoff OVERALL STORMWATER MANAGEMENT MASTERVOAA 24-hrD 100-Year Rainfall=9.14" Prepared by Timmons Group Printed 3/21/2022 LJ...1—. AM4 n 4 n �. .. /.. nOnnO /l nnn LJ...1...!` G Il C..p........ C..I. d:...... I !` n--- Summary for Subcatchment 9S: Pre Bypass Runoff = 1.68 cfs @ 12.13 hrs, Volume= 0.112 af, Depth> 4.07" Routed to Link 24L : AP Pre Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hrD 100-Year Rainfall=9.14" Area (ac) CN Description 0.320 61 >75% Grass cover, Good, HSG B n n,n n. 0.330 62 Weighted Average 0.320 96.97% Pervious Area 0.010 3.03% Impervious Area Tc Length Slope Velocity Capacity Description lmin) lfPPfi /ff/ff1 !ff/carl /rfcl 6.0 Direct Entry, Subcatchment 9S: Pre Bypass Hydrograph ❑ Runoff NOAA 24-hr D 100-Year Rainfall=9.14" Runoff Area=0.330 ac Runoff Volume=0.112 of Runoff Depth>4.07" Tc=6.0 min CN=62 0 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) OVERALL STORMWATER MANAGEMENT MASTERVOAA 24-hrD 100-Year Rainfall=9.14" Prepared by Timmons Group Printed 3/21/2022 Summary for Subcatchment 13S: BY PASS POST Runoff = 10.54 cfs @ 12.13 hrs, Volume= 0.752 af, Depth> 6.35" Routed to Link 21 L : AP post Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hrD 100-Year Rainfall=9.14" Area (ac) CN Description 0.780 98 0.640 61 >75% Grass cover, Good, HSG B 1.420 81 Weighted Average 0.640 45.07% Pervious Area 0.780 54.93% Impervious Area Tc Length Capacity Description Direct Entry, Subcatchment 13S: BY PASS POST Hydrograph ❑ Runoff NOAA 24-hr D 100-Year Rainfall=9.14rr Runoff Area=1.420 ac Runoff Volume=0.752 of --- -Runoff Depth>6.35" Tc=6.0 min - C N--81- - -;----r------7---- 0 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) OVERALL STORMWATER MANAGEMENT MASTERVOAA 24-hrD 100-Year Rainfall=9.14" Prepared by Timmons Group Printed 3/21/2022 Summary for Subcatchment 15S: TO UGD Runoff = 17.96 cfs @ 12.13 hrs, Volume= 1.324 af, Depth> 7.03" Routed to Pond 20P : UGD Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hrD 100-Year Rainfall=9.14" Area (ac) CN Description * 1.610 98 0.650 61 >75% Grass cover, Good, HSG B 2.260 87 Weighted Average 0.650 28.76% Pervious Area 1.610 71.24% Impervious Area Tc Length Capacity Description 6.0 Direct Entry, Subcatchment 15S: TO UGD Hydrograph 20 ' 19 ' 13 -----------------7----',---;--- --;----;----',--- Ip__,dK,o�-24-1hr-_D- 17 _, _T _ I _7 _r _ I : _I -T -r -, -, T '400-Year-Rainfalir-9-A4"-- 16 ---,----T----i--- T---- r---, -- -: i- 15 ' ____ L___ J__ Run6ffAreei=2.260'ac 14 -----------------1____��--__J_-. 13 - ------- T------------ - - ---- -- Y1 - �,32t, of -Auffl ' o'Voum' 1: 12 Runoff Depth?7.03" 3 10 -----------------1----L---J-- __�1____1____��_. __- -' - --- _9 Tc= 8 ------------ --- - -- ---- --- - - ---- --- �+ 'p 7 YN='O% 6 i 5 -------T--------*----r----- ------+----r _.--r--------*____ 4 i z 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) G Runoff OVERALL STORMWATER MANAGEMENT MASTERVOAA 24-hrD 100-Year Rainfall=9.14" Prepared by Timmons Group Printed 3/21/2022 Summary for Pond 7P: Ex. Pond [821 Warning: Early inflow requires earlier time span [441 Hint: Outlet device #1 is below defined storage [441 Hint: Outlet device #2 is below defined storage [921 Warning: Device #5 is above defined storage Inflow Area = 3.340 ac, 71.56% Impervious, Inflow Depth > 7.03" for 100-Year event Inflow = 26.55 cfs @ 12.13 hrs, Volume= 1.957 of Outflow = 21.90 cfs @ 12.17 hrs, Volume= 1.957 af, Atten= 18%, Lag= 2.9 min Primary = 21.90 cfs @ 12.17 hrs, Volume= 1.957 of Routed to Link 24L : AP Pre Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 471.41' @ 12.17 hrs Surf.Area= 2,094 sf Storage= 2,658 cf Plug -Flow detention time= (not calculated: outflow precedes inflow) Center -of -Mass det. time= 0.4 min ( 753.4 - 753.0 ) Volume Invert Avail.Storage Storage Description #1 469.00' 14,632 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 469.00 76 0 0 470.00 905 491 491 471.00 1,824 1,365 1,855 472.00 2,483 2,154 4,009 473.00 3,159 2,821 6,830 474.00 3,885 3,522 10,352 475.00 4,676 4,281 14,632 Device Routing Invert Outlet Devices #1 Primary 468.36' 18.0" Round Culvert L= 5.0' Ke= 0.100 Inlet / Outlet Invert= 468.36' / 467.66' S= 0.1400 '/' Cc= 0.900 n= 0.020 Corrugated PE, corrugated interior, Flow Area= 1.77 sf #2 Primary 468.36' 10.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Primary 470.83' 1.0" W x 0.8" H Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #4 Primary 472.96' 2.0" x 2.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads #5 Primary 475.00' Custom Weir/Orifice, Cv= 2.62 (C= 3.28) Head (feet) 0.00 1.00 Width (feet) 30.00 50.00 rimary OutFlow Max=21.59 cfs @ 12.17 hrs HW=471.35' (Free Discharge) 1=Culvert (Inlet Controls 17.36 cfs @ 9.82 fps) 2=Orif ice/G rate (Orifice Controls 4.21 cfs @ 7.72 fps) 3=Orif ice/G rate (Orifice Controls 0.02 cfs @ 3.35 fps) =Orif ice/G rate ( Controls 0.00 cfs) S=Custom Weir/Orifice ( Controls 0.00 cfs) OVERALL STORMWATER MANAGEMENT MASTER'VOAA 24-hrD 100-Year Rainfall=9.14" Prepared by Timmons Group Printed 3/21/2022 Pond 7P: Ex. Pond Hydrograph _-- _-------t--------*-------r--- 0Primary 2 ____________i--------r---y____r ---nf�wArea=�34Qbc- 26 I I 2 -I -- #3eclk ;lev"474.4-It - i i Zo I III-Storage=2s58_pf ---- _ 18 ___y____I____�____I____r___y_-__+_-------+--------r___y____r___ I I I I I I I I I ,u 1e / 1___J____L___J __J_ ____11 ___i_---i ___ i____i____ I I II i i I I I I p 14 , I I I I I I I 12 ' ____I____I ____I __ ____I____ ____I____I I I I I I I I I I I I I I 10 , I I I I I I I I a ___ I____I ______ I I II I I II I I I , I I I I I I I I I I I a 1 12 13 Time (horns) OVERALL STORMWATER MANAGEMENT MASTERVOAA 24-hrD 100-Year Rainfall=9.14" Prepared by Timmons Group Printed 3/21/2022 Summary for Pond 20P: UGD [821 Warning: Early inflow requires earlier time span [931 Warning: Storage range exceeded by 0.55' [881 Warning: Qout>Qin may require smaller dt or Finer Routing Inflow Area = 2.260 ac, 71.24% Impervious, Inflow Depth > 7.03" for 100-Year event Inflow = 17.96 cfs @ 12.13 hrs, Volume= 1.324 of Outflow = 18.67 cfs @ 12.11 hrs, Volume= 1.323 af, Atten= 0%, Lag= 0.0 min Primary = 18.67 cfs @ 12.11 hrs, Volume= 1.323 of Routed to Link 21 L : AP post Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 105.55' @ 12.11 hrs Storage= 0.065 of Plug -Flow detention time= 5.4 min calculated for 1.318 of (100% of inflow) Center -of -Mass det. time= 4.7 min ( 757.7 - 753.0 ) Volume Invert Avail.Storage Storage Description #1 100.00, 0.065 of 60.0" Round Pipe Storage L= 145.0' Device Routing Invert Outlet Devices #1 Primary 100.00' 18.0" Round Culvert L= 25.0' Ke= 0.100 Inlet / Outlet Invert= 100.00' / 98.00' S= 0.0800 '/' Cc= 0.900 n= 0.012 Corrugated PP, smooth interior, Flow Area= 1.77 sf #2 Device 1 100.00' 8.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Device 1 102.72' 16.0" W x 8.0" H Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #4 Device 1 104.62' weir, Cv= 2.62 (C= 3.28) Head (feet) 0.00 1.00 Width (feet) 1.00 6.00 Primary OutFlow Max=17.77 cfs @ 12.11 hrs HW=105.49' (Free Discharge) t1=Culvert (Passes 17.77 cfs of 25.26 cfs potential flow) 2=Orifice/Grate (Orifice Controls 3.82 cfs @ 10.93 fps) 3=Orifice/Grate (Orifice Controls 6.68 cfs @ 7.51 fps) =weir (Weir Controls 7.27 cfs @ 2.64 fps) OVERALL STORMWATER MANAGEMENT MASTER'VOAA 24-hrD 100-Year Rainfall=9.14" Prepared by Timmons Group Printed 3/21/2022 Pond 20P: UGD Hydrograph J____I____1___I____L___J____ L___ L ■ Inflow I ■Primary 20 /', y =�2� 1-nioWT rea a 19 + r c- 118 --_J _A_1 __l_ _a_-Q5__ _ ,7 ',, ev_�::_I ---I-------- -_-_-_ Pe_ k ._-5-I-5-'- ;- 16---'----I---- ---'I --a--�II---=y____I____7____I____ -5--`r-i- --�-_I6- _/ ____I_StbF =;4 �----I- 1 ________ ___1_______ I __ ____I______________ ---- --- 13 ,Z / ,� / / / ___J____I____1 _I _L _J _I _1 _I _L _J _L V 11 c 10 / '' I ___ ___ LL g a 8 ,' I 4 /' ___ '___J____1___J____L___J____L___ / / I I I I 1 12 13 Time (horns) OVERALL STORMWATER MANAGEMENT MASTERVOAA 24-hrD 100-Year Rainfall=9.14" Prepared by Timmons Group Printed 3/21/2022 Summary for Link 21 L: AP post Inflow Area = 3.680 ac, 64.95% Impervious, Inflow Depth > 6.76" for 100-Year event Inflow = 28.98 cfs @ 12.12 hrs, Volume= 2.074 of Primary = 28.98 cfs @ 12.12 hrs, Volume= 2.074 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Link 21L: AP post Hydrograph FE ]—I n—fl.—. ❑ Primary Time (hours) OVERALL STORMWATER MANAGEMENT MASTERVOAA 24-hrD 100-Year Rainfall=9.14" Prepared by Timmons Group Printed 3/21/2022 LJ...1—. AM4 n 4 n 1� ..1. nOGGO /l Ol1O � LJ...1—. AM C..p........ C..I. d:...... I !` n--- 41 Summary for Link 24L: AP Pre Inflow Area = 3.670 ac, 65.40% Impervious, Inflow Depth > 6.77" for 100-Year event Inflow = 23.41 cfs @ 12.17 hrs, Volume= 2.069 of Primary = 23.41 cfs @ 12.17 hrs, Volume= 2.069 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Link 24L: AP Pre Hydrograph 1 E I 12391 ah ;_ -- 2341cfs Inflow Area=3.670 ac- ' I 1 I I I I I I I 1 1 1 1 1 1 1 _11 _I _L _J _L 1 1 I I 1 1 1 1 1 1 I I 1 1 I I 1 1 I I I 1 1 I I I I I I I I I I I I I 1 I I I 1 1 I I I -------------------------- I 1 1 I I 1 1 I 1 1 I I I -------------------------------- 1 1 1 12 13 14 15 16 Time (hours) ❑ Inflow ❑ Primary OVERALL STORMWATER MANAGEMENT MASTER PLAN ROUTING Cable of Contents Prepared by Timmons Group Printed 3/21/2022 TABLE OF CONTENTS Project Reports 1 Routing Diagram 2 Project Notes 3 Area Listing (all nodes) 4 Soil Listing (all nodes) 5 Ground Covers (all nodes) 6 Pipe Listing (all nodes) Current Event 7 Node Listing 8 Subcat 8S: Pre to Pond 9 Subcat 9S: Pre Bypass 10 Subcat 13S: BY PASS POST 11 Subcat 15S: TO UGD 12 Pond 7P: Ex. Pond 14 Pond 20P: UGD 16 Link 21 L: AP post 17 Link 24L: AP Pre 8S Preto P nd 9S A Pr Bypass Ex. Pon\ 24L AP Pre Subcat Reach Aon Llnk /15S To EPond Post 13S 7P BY PASS P T x. Pond 21L AP post PHASE 1 STORMWATER MANAGEMENT MASTER PLAN ROUTING CALCULATIONS Prepared by Timmons Group Printed 3/21/2022 Project Notes Rainfall events imported from "NRCS-Rain.txt" for 8701 VA Albemarle Zone-1 Rainfall events imported from "NRCS-Rain.txt" for 8701 VA Albemarle Zone-1 PHASE 1 STORMWATER MANAGEMENT MASTER PLAN ROUTING CALCULATIONS Prepared by Timmons Group Printed 3/21/2022 Area Listing (all nodes) Area CN Description (acres) (subcatchment-numbers) 4.130 98 (8S, 9S, 13S, 15S) 3.000 61 >75% Grass cover, Good, HSG B (8S, 9S, 13S, 15S) VA 1101CA W_1N=F_1 PHASE 1 STORMWATER MANAGEMENT MASTER PLAN ROUTING CALCULATIONS Prepared by Timmons Group Printed 3/21/2022 Soil Listing (all nodes) Area Soil Subcatchment (acres) Group Numbers 0.000 HSG A 3.000 HSG B 8S, 9S, 13S, 15S 0.000 HSG C 0.000 HSG D 4.130 Other 8S, 9S, 13S, 15S 7.130 TOTAL AREA PHASE 1 STORMWATER MANAGEMENT MASTER PLAN ROUTING CALCULATIONS Prepared by Timmons Group Printed 3/21/2022 Ground Covers (all nodes) HSG-A HSG-B HSG-C HSG-D Other Total Ground Subcatchment (acres) (acres) (acres) (acres) (acres) (acres) Cover Numbers 0.000 0.000 0.000 0.000 4.130 4.130 8S, 9S, 13S, 15S 0.000 3.000 0.000 0.000 0.000 3.000 >75% Grass cover, Good 8S, 9S, 13S, 15S 0.000 3.000 0.000 0.000 4.130 7.130 TOTAL AREA PHASE 1 STORMWATER MANAGEMENT MASTER PLAN ROUTING CALCULATIONS Prepared by Timmons Group Printed 3/21/2022 Pipe Listing (all nodes) Line# Node In -Invert Out -Invert Length Slope n Width Diam/Height Inside -Fill Number (feet) (feet) (feet) (ft/ft) (inches) (inches) (inches) 1 7P 468.36 467.66 5.0 0.1400 0.020 0.0 18.0 0.0 2 27P 468.36 467.66 5.0 0.1400 0.020 0.0 18.0 0.0 PHASE 1 STORMWATER MANAGEMENT MASTER JW0AA 24-hrD 100-Year Rainfall=9.14" Prepared by Timmons Group Printed 3/21/2022 HydroCAD® 10.10-7a s/n 08663 © 2021 HydroCAD Software Solutions LLC Page 7 Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment8S: Pre to Pond Runoff Area=3.340 ac 71.56% Impervious Runoff Depth>7.03" Tc=6.0 min CN=87 Runoff=26.55 cfs 1.957 of Subcatchment9S: Pre Bypass Runoff Area=0.170 ac 5.88% Impervious Runoff Depth>4.19" Tc=6.0 min CN=63 Runoff=0.89 cfs 0.059 of Subcatchment13S: BY PASS POST Runoff Area=0.170 ac 5.88% Impervious Runoff Depth>4.19" Tc=6.0 min CN=63 Runoff=0.89 cfs 0.059 of Subcatchment15S: To Ex. Pond Post Runoff Area=3.450 ac 49.86% Impervious Runoff Depth >6.11" Tc=6.0 min CN=79 Runoff=24.91 cfs 1.758 of Pond 7P: Ex. Pond Peak Elev=471.41' Storage=2,658 cf Inflow=26.55 cfs 1.957 of Outflow=21.90 cfs 1.957 of Pond 27P: Ex. Pond Peak Elev=471.20' Storage=2,232 cf Inflow=24.91 cfs 1.758 of Outflow=20.89 cfs 1.758 of Link 21 L: AP post Inflow=21.69 cfs 1.817 of Primary=21.69 cfs 1.817 of Link 24L: AP Pre Inflow=22.69 cfs 2.017 of Primary=22.69 cfs 2.017 of Total Runoff Area = 7.130 ac Runoff Volume = 3.834 of Average Runoff Depth = 6.45" 42.08% Pervious = 3.000 ac 57.92% Impervious = 4.130 ac PHASE 1 STORMWATER MANAGEMENT MASTER JWOAA 24-hrD 100-Year Rainfall=9.14" Prepared by Timmons Group Printed 3/21/2022 Summary for Subcatchment 8S: Pre to Pond Runoff = 26.55 cfs @ 12.13 hrs, Volume= 1.957 af, Depth> 7.03" Routed to Pond 7P : Ex. Pond Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hrD 100-Year Rainfall=9.14" Area (ac) CN Description 2.390 98 0.950 61 >75% Grass cover, Good, HSG B 3.340 87 Weighted Average 0.950 28.44% Pervious Area 2.390 71.56% Impervious Area Tc Length Capacity Description 6.0 Direct Entry, Subcatchment 8S: Pre to Pond Hydrograph I---_ - - - - f------- - + - - -- 28 2555 cfa 26 ---'--�IO�A 24_hr D - - 24 -- 400 Year Rairifallr9.44"-- 22 --- RunbfFArrea=3.-340 ac- 20 18 Runoff Volume=1.957'aT- V 16 Runoff D"th;�,7.0_ 4 -- j--- --- T,c=6'60-MIM- L -~ 12 i___ __ 10 f N=,67 a 6 4 2 0. 5 6 10 Time (hours) 15 16 17 18 19 20 G Runoff PHASE 1 STORMWATER MANAGEMENT MASTER JWOAA 24-hrD 100-Year Rainfall=9.14" Prepared by Timmons Group Printed 3/21/2022 Summary for Subcatchment 9S: Pre Bypass Runoff = 0.89 cfs @ 12.13 hrs, Volume= 0.059 af, Depth> 4.19" Routed to Link 24L : AP Pre Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hrD 100-Year Rainfall=9.14" a (ac) CN Description 0.160 61 >75% Grass cover. Good. HSG B 0.170 63 Weighted Average 0.160 94.12% Pervious Area 0.010 5.88% Impervious Area Tc Length Capacity Description 6.0 Direct Entry, Subcatchment 9S: Pre Bypass Hydrograph 0.95 T � F 089 cfs T i i os NOAA 24-hr-U 0.8L - -- ; -----;100-Yeiar RainfaU--;9A4'-'- 0.75---J-------J----L---J----L-- --- L--_r----i--_r----i--__I----i--- 0.7 J -- ------ Runoff -Area--O.Mac- 006 ft0off-�oC,OMQ .p�9;a-- 0.55 ---; --- 'Aunoff Depth>4.1a 0.5- ----------------------4-- - ---- --__`---- ---- y. 045 c=6.0 min 04 0.35 7____r___r____r___r____r_ __r___ 'i____r___ 'i____r___rr-N-,6$_ 0.25 02 0.15 -- - - - -- - -- ---- 0.1 10 11 12 13 14 15 16 17 18 19 20 Time (hours) ■ Runoff PHASE 1 STORMWATER MANAGEMENT MASTER 19'OAA 24-hrD 100-Year Rainfall=9.14" Prepared by Timmons Group Printed 3/21/2022 Summary for Subcatchment 13S: BY PASS POST Runoff = 0.89 cfs @ 12.13 hrs, Volume= 0.059 af, Depth> 4.19" Routed to Link 21 L : AP post Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hrD 100-Year Rainfall=9.14" Area (ac) CN Description ' 0.010 98 0.160 61 >75% Grass cover, Good, HSG B 0.170 63 Weighted Average 0.160 94.12% Pervious Area 0.010 5.88% Impervious Area Tc Length Capacity Description 6.0 Direct Entry, Subcatchment 13S: BY PASS POST Hydrograph 0.95 __________ ------------------ ---- 089 cfs os NOAA 21,4-hr: -U 0.8 L-1!! -- ---; 00-Year Rainfal�T�1t4'-'- 0.75---L----L---L----L--- ---L--------L--------L----I----L--- 0.7---J----'�--- ---- --- ------Runoff-Area--O.Mac- 006 RuRoff- oCumQ' .0--9-af0.55 -------�---�------- ---;--- '�I-Runof�-Depth>4.1a0.5 ___�----------------- -----__�--__`-------- 045 i Tc=6.0 min040.35 _ __r___'i____r___'i____r___���_0.2502 0.15 - --- ---- 0.1--------------r_______ - _____ r____r___r___ 10 11 12 13 14 15 16 17 18 19 20 Time (hours) ■ Runoff PHASE 1 STORMWATER MANAGEMENT MASTER JWOAA 24-hrD 100-Year Rainfall=9.14" Prepared by Timmons Group Printed 3/21/2022 Summary for Subcatchment 15S: To Ex. Pond Post Runoff = 24.91 cfs @ 12.13 hrs, Volume= 1.758 af, Depth> 6.11" Routed to Pond 27P : Ex. Pond Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hrD 100-Year Rainfall=9.14" Area (ac) CN Description 1.720 98 1.730 61 >75% Grass cover, Good, HSG B 3.450 79 Weighted Average 1.730 50.14% Pervious Area 1.720 49.86% Impervious Area Tc Length Capacity Description 6.0 Direct Entry, Subcatchment 15S: To Ex. Pond Post Hydrograph 26 24 22 20 I I 18 16 y 14 I I 3 LL 12 10 I I I 8 I I I I I I 6 I I I I I I I I I I I I 4 -I Y 2 I 0 F�f 5 6 10 i____ L___ J____ L___i____ i____ -DAfi'D- 00-Year Ralnfall9.14" ___Runbf_AreA3A5-acL _ ,71;af- - -Runof Dpth;>� ---T=8I-0r ---N1 9 y _ I _} Y T Time (hours) 17 18 19 20 ■ Runoff PHASE 1 STORMWATER MANAGEMENT MASTER JWOAA 24-hrD 100-Year Rainfall=9.14" Prepared by Timmons Group Printed 3/21/2022 Summary for Pond 7P: Ex. Pond [821 Warning: Early inflow requires earlier time span [441 Hint: Outlet device #1 is below defined storage [441 Hint: Outlet device #2 is below defined storage [921 Warning: Device #5 is above defined storage Inflow Area = 3.340 ac, 71.56% Impervious, Inflow Depth > 7.03" for 100-Year event Inflow = 26.55 cfs @ 12.13 hrs, Volume= 1.957 of Outflow = 21.90 cfs @ 12.17 hrs, Volume= 1.957 af, Atten= 18%, Lag= 2.9 min Primary = 21.90 cfs @ 12.17 hrs, Volume= 1.957 of Routed to Link 24L : AP Pre Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 471.41' @ 12.17 hrs Surf.Area= 2,094 sf Storage= 2,658 cf Plug -Flow detention time= (not calculated: outflow precedes inflow) Center -of -Mass det. time= 0.4 min ( 753.4 - 753.0 ) Volume Invert Avail.Storage Storage Description #1 469.00' 14,632 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 469.00 76 0 0 470.00 905 491 491 471.00 1,824 1,365 1,855 472.00 2,483 2,154 4,009 473.00 3,159 2,821 6,830 474.00 3,885 3,522 10,352 475.00 4,676 4,281 14,632 Device Routing Invert Outlet Devices #1 Primary 468.36' 18.0" Round Culvert L= 5.0' Ke= 0.100 Inlet / Outlet Invert= 468.36' / 467.66' S= 0.1400 '/' Cc= 0.900 n= 0.020 Corrugated PE, corrugated interior, Flow Area= 1.77 sf #2 Primary 468.36' 10.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Primary 470.83' 1.0" W x 0.8" H Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #4 Primary 472.96' 2.0" x 2.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads #5 Primary 475.00' Custom Weir/Orifice, Cv= 2.62 (C= 3.28) Head (feet) 0.00 1.00 Width (feet) 30.00 50.00 rimary OutFlow Max=21.59 cfs @ 12.17 hrs HW=471.35' (Free Discharge) 1=Culvert (Inlet Controls 17.36 cfs @ 9.82 fps) 2=Orif ice/G rate (Orifice Controls 4.21 cfs @ 7.72 fps) 3=Orif ice/G rate (Orifice Controls 0.02 cfs @ 3.35 fps) =Orif ice/G rate ( Controls 0.00 cfs) S=Custom Weir/Orifice ( Controls 0.00 cfs) PHASE 7 STORMWATER MANAGEMENT MASTER ROAA 24-hrD 100-Year Rainfall=9.14" Prepared by Timmons Group Printed 3/21/2022 Pond 7P: Ex. Pond Hydrograph _-- _-------t--------*-------r--- 0Primary 2 ____________i--------r---y____r ---nf�wArea=�34Qbc- 26 I I 2 -I -- #3eclk ;lev"474.4-It - i i Zo I III-Storage=2s58_pf ---- _ 18 ___y____I____�____I____r___y_-__+_-------+--------r___y____r___ I I I I I I I I I ,u 18 / 1___J____L___J __J_ ____11 ___i_---i ___ i____i____ II II i i I I I I p 14 , I I I I I I I 12 ' ____I____I ____I __ ____I____ ____I____I I I I I I I I I I I I I I 10 , I I I I I I I I a ___ I____I ______ I I II I I II I I I , I I I I I I I I I I I a 1 12 13 Time (horns) PHASE 1 STORMWATER MANAGEMENT MASTER JWOAA 24-hrD 100-Year Rainfall=9.14" Prepared by Timmons Group Printed 3/21/2022 Summary for Pond 27P: Ex. Pond [821 Warning: Early inflow requires earlier time span [441 Hint: Outlet device #1 is below defined storage [441 Hint: Outlet device #2 is below defined storage [921 Warning: Device #5 is above defined storage Inflow Area = 3.450 ac, 49.86% Impervious, Inflow Depth > 6.11" for 100-Year event Inflow = 24.91 cfs @ 12.13 hrs, Volume= 1.758 of Outflow = 20.89 cfs @ 12.17 hrs, Volume= 1.758 af, Atten= 16%, Lag= 2.7 min Primary = 20.89 cfs @ 12.17 hrs, Volume= 1.758 of Routed to Link 21 L : AP post Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 471.20' @ 12.17 hrs Surf.Area= 1,955 sf Storage= 2,232 cf Plug -Flow detention time= (not calculated: outflow precedes inflow) Center -of -Mass det. time= 0.3 min ( 769.0 - 768.6 ) Volume Invert Avail.Storage Storage Description #1 469.00' 14,632 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 469.00 76 0 0 470.00 905 491 491 471.00 1,824 1,365 1,855 472.00 2,483 2,154 4,009 473.00 3,159 2,821 6,830 474.00 3,885 3,522 10,352 475.00 4,676 4,281 14,632 Device Routing Invert Outlet Devices #1 Primary 468.36' 18.0" Round Culvert L= 5.0' Ke= 0.100 Inlet / Outlet Invert= 468.36' / 467.66' S= 0.1400 '/' Cc= 0.900 n= 0.020 Corrugated PE, corrugated interior, Flow Area= 1.77 sf #2 Primary 468.36' 10.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Primary 470.83' 1.0" W x 0.8" H Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #4 Primary 472.96' 2.0" x 2.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads #5 Primary 475.00' Custom Weir/Orifice, Cv= 2.62 (C= 3.28) Head (feet) 0.00 1.00 Width (feet) 30.00 50.00 rimary OutFlow Max=20.58 cfs @ 12.17 hrs HW=471.14' (Free Discharge) 1=Culvert (Inlet Controls 16.53 cfs @ 9.35 fps) 2=Orif ice/G rate (Orifice Controls 4.04 cfs @ 7.40 fps) 3=Orif ice/G rate (Orifice Controls 0.01 cfs @ 2.53 fps) =Orif ice/G rate ( Controls 0.00 cfs) S=Custom Weir/Orifice ( Controls 0.00 cfs) PHASE 7 STORMWATER MANAGEMENT MASTER ROAA 24-hrD 100-Year Rainfall=9.14" Prepared by Timmons Group Printed 3/21/2022 Pond 27P: Ex. Pond Hydrograph I I I I I I I I I I I I I I I I I I I I a�.e+as I I I I I I I ■ Primary 26 --- +I nilllowiAr aO.- SO ac 24 1 1 I I I I - I -----------i---=----L ------ PeAkf lev�47r —ZO' — 22 I I 1 20 89 cfs 20 ' I 1 1 1 1 1 1 - --_ 11 I I I I t�rage 7,23Z - 18- I I I I I I I 1 16 I -I---- L--- J---- L--- � i u I I I I I 3 c I I I 10 i i i _I _+ —I —t —- _I —+ —I I I I I I I I I I 1 1 1 1 1 1 I I I 4-1 - -----I- ________ __-------------i 1 12 13 Time (horns) PHASE 1 STORMWATER MANAGEMENT MASTER i9'OAA 24-hrD 100-Year Rainfall=9.14" Prepared by Timmons Group Printed 3/21/2022 Summary for Link 21 L: AP post Inflow Area = 3.620 ac, 47.79% Impervious, Inflow Depth > 6.02" for 100-Year event Inflow = 21.69 cfs @ 12.17 hrs, Volume= 1.817 of Primary = 21.69 cfs @ 12.17 hrs, Volume= 1.817 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Link 21L: AP post Hydrograph , - ---------- --- ---- -- r____I____r___r____r_ ❑Inflow 4 2111111 ,�''� ❑Primary 2 In flow Area=3.620 --------22 ac- 21 , ---,----I----T---- - 27832 •'.'', .,.� r---1- TT1* -r------------- TL___JII 1 _L J1y -�T -T --r -lI - _II ___ J____ Lrrr 8 _T_________I____r___ _____I____T____I____ 7 L_ -_ L___JL___ 6 ___ y____I____ 7____I____r ___ y____ 4 ------------ ------ *------- - - - - -- 1 12 13 14 Time (hours) PHASE 1 STORMWATER MANAGEMENT MASTER JWOAA 24-hrD 100-Year Rainfall=9.14" Prepared by Timmons Group Printed 3/21/2022 Summary for Link 24L: AP Pre Inflow Area = 3.510 ac, 68.38% Impervious, Inflow Depth > 6.89" for 100-Year event Inflow = 22.69 cfs @ 12.17 hrs, Volume= 2.017 of Primary = 22.69 cfs @ 12.17 hrs, Volume= 2.017 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Link 24L: AP Pre Hydrograph 2 221 24 ___T__ ________ ___ 3 ' 222 - - I 22 fi9 ci I I I 21 _--_____'____I____�___� ' I I I I I 12 LL 11 ,____T____I____r___r Qi - 8 7 8 5 —__l____I_ _- Inflow Area=3.510 ac I -------- II I I I I I I I I I I I I I I I I 1 12 13 14 Time (hours) I _—_J____ L___ J____ L___ I ---- ---- L--- J____ L___ ------------------- _ _I---- L--- J _L T____ _— FE ]-I n-fl.-w ❑ Primary PHASE 1 STORMWATER MANAGEMENT MASTER PLAN ROUTING CAbb/e of Contents Prepared by Timmons Group Printed 3/21/2022 TABLE OF CONTENTS Project Reports 1 Routing Diagram 2 Project Notes 3 Area Listing (all nodes) 4 Soil Listing (all nodes) 5 Ground Covers (all nodes) 6 Pipe Listing (all nodes) Current Event 7 Node Listing 8 Subcat 8S: Pre to Pond 9 Subcat 9S: Pre Bypass 10 Subcat 13S: BY PASS POST 11 Subcat 15S: To Ex. Pond Post 12 Pond 7P: Ex. Pond 14 Pond 27P: Ex. Pond 16 Link 21 L: AP post 17 Link 24L: AP Pre FORM LO 201 STORMWATER INLET COMPUTATIONS SHEET OF ROUTE PROJECT PREMIER CIRLCE DESIGNER: K. RARGER OATS wimp 2 CHECKED: UNITS ENGLUiH INLETSOFT RY ENSOFTEC DATE: ylMM LD-229 PROJECT: PREMIERCIRCLE STORM SEWER DESIGN COMPUTATIONS LOCATION: ALBEMARLECOUNTY COUNTY: ChadcftesAle STORM FREQUENCY 10 Desipell by: K BARGER Checked by: UNITS ENGLISH PIPE NO. FROMPoWT TO PINT DRAIN. AREA 'A' Acre 3 RUNOFF COEFF. 'C' C CA RJLEY TOME M.W RAIN FALL WR, B RIRJOFF INVERTELEVATIONS LENGTH of Pipe Ft 12 SLOPE F[fft U SIZE (M.Or SpNRitt) a 14 SHAPE Number of Pipes Ce iry ITS IS Friction Slole FUEL NORMAL FLOW FLOW TIME REMARKS IS INCRE- NEW 5 ACCUM- ULATED 6 Lahml CFS To Q CPS 9 UPPER END 10 LOWER END II Deplb of FIow,M Ft Areeof FIow,An SIR H. Ft Vn FVSec 16 En Ft MCRE- MENT Mm.e I] ACCUAIU -I. M.w 1 REFERENCE 1 STA. REFERENCE 2 STA 103 100 102 000 0W O6 5.13 650 0W 421 a10W 4692E 4247 001789 18 Cl—W 1 1405 OCOPIO 056 061 031 695 131 0.10 523 105 IN IOJ 061 OB2 050 050 5W 654 0W 327 47193 4M 10 W91 003W4 12 Circular 1 6.19 O00880 052 041 026 799 1.51 013 5.13 141 142 106 024 0W 0.14 0.14 5W 654 0W 094 4nN 4M" 3628 0O3 12 Circular 1 6.19 O"M 026 0.17 0.15 569 07 0.11 Sill DEQ Virginia Runoff Reduction Method Re -Developer O2011 BMP Standards and Specifications O 2013 Draft BMP Standards and Specifications Project Name: Premier Circle- Stormwater Master Plan Re Information Project (Treatment Volume and Loads) Enter Total Disturbed Area (acres) Pre-ReDevelopment land Cover (acres( A Soils BSoils CSoils DSells Totals Forest/Open Space (acres) -- undisturbed forest/open space Ir Managetl Tudlacres) -- disturbQ graded for yards or other turf to be mowed/managed 1.28 1.28 Impervious Cover (acres) 240 2.40 data Input cells constant values calculation cells Linearprai No Land cover areas entered correctly? Total disturbed area entered? Post -Development land Cover (acres( A Soils BSoils CSoils DSoils Totals Forest/Open Space(acres)-- undisturbeQ protected forest/o s or reforested land 0'� Managed Turf(acres) disturted, graded for yards or other turf to be mrwetl/man ed 1.29 1.29 ImperviousCover(acres) 239 2.39 Area Check OK. OK. OK. OK. 3.68 Pre-ReDevelopment Listed Adjusted' Post ReDev. & New Impervious Forest/Open Space Cover (acres) 0.00 0.00 Forest/Or(acresipen ace 0.00 CoveWeighted Ra(forest) am 0.00 Weighted Ranorest) 0.00 %Forest 0% 0% %Forest 0% Managed Turf Cover (acres) 1.28 1.28 Managed Turf Cover 129 (acres) Weighted Rv(turf) 0.20 0.20 Weighted Rv(turf) 0.20 %Managed Turf 35% 35% %Managetl Turf 35% Impervious Cover (acres) 2.40 2.40 Impe(acresiCover 2.39 R,dimpervious) 0.95 0.95 Rat(impervious) 0.95 %Impervious 65% 65% %Impervious 65% Total She Area (acres) 3.0 3.68 Final Site Area (acres) 3.68 Site ga 0.69 0.69 Final Post Den She Rv 0.69 Treatment Volume and Nutrient Load Final PaM- Pre-ReDevelopment Treatment Volume 0.2113 0.2113 Development 0.2107 (acre-fit) TreatmentVolume (acre-ft) FinalP.A- Pre-ReDevelopment Treatment Volume 9206 9,206 Development 9,178 (cubicfeet) Treatment Volume (cubicfeet) Pre-ReDevelopment TP Load Final Post- (lb/yr) 5.78 5.78 Development TP Load 5.77 (lb/yr) PmRe0evelopmemTP Loatl per arm Final Past-Development TP Ilbent r) 1.57 1.57 Lead per arm 1.57 (lb/ave/yr) Baseline TP Load (lbl a) (0A116s/ave/yr applied to pre-retlevelopment area mcluding pervious 1.51 land proposed for new impervious cover) 'Adjusted Land Cover Summary: ore ReDevelopment land cover minus pervious land cover (forenlopen spare or m rtagedhaD acreage proposedfor new impervious cover. adjusted total acreage is consistent with Past-ReDevelopment arreage (minus acreage of new impervious cover). ^obmn I shows bad reduction requdementfor new impervious cover (based on new development load limit 0.41 Ihs/acre/year). TP Wad Reduction Required (lb/yr) D Soil 0.05 0.25 0.95 Post-ReDevebpmeM Forest/Open Space Cover (acres) 003 Weighted Rv(forest) 0.00 %Forest 0% Managed Turf Cover (acres) 1.29 Weighted Be (turf) 0.20 %Managed Turf 35% ReDev. Impervious Cover (acres) 2.39 M(impervious) 0.95 %Impervious 65% TotalRaay.SRe Area (a[res) 3b8 ReDev She Rv 0.69 Treatment Volume and Nutrient Load 1.14 Post-ReDevelopment TreatmentVolume 0.2107 (a[rai Post-ReDevelopment TrertmeMVolume 9,178 (cu ds feet) Port-ReDevebpmeM Wad (TP) 5.7/ (lb/yr)a Past-ReDevelopment TP Load per acre pb/acrayr) Max. Reduction acquiredre (Below P- TO% ReBevelopment Load) TP Load Reducdon Required for Redeveloped Area 1.14 (lb/vrl Nitrogen Loads (Informational Purposes Only) Final Post -Development TN Load Pre-ReDevelopment TN Load(Ib/yr) 41.38 (Past- ReDevelopment&New 41.25 Impervious) (b/yr) Land Cover Summary -Post Past -Development New Impervious New Impervious Cover crest 0.00 a Rv(impervious) Port-Oav "dare n Treatment Volume (ecre-R) rDevel.,olme (cubic et) Post -Development TP Wad(lb/yr) TP Load Reduction Required for New 0 .Pervious Area (lb/vr) DEQ Virginia Runoff Reduction Method Re-Developm 02012 LIMP Standards and Specifications 02013 Draft BMP Standards and Specifications Project Name: Premier Circle - Phase l Plan Date: 3/21/2022 Linear Development Project? No Site Information Post -Development Project (Treatment Volume and Loads) Enter Total Disturbed Area (acres) data Input cells constant values calculation cells Linearproject? No 5=71 Land cover areas entered correctly? r Total disturbed area entered? To LOAD REDUCTION NOTREQUIRED Pre-ReDevelopment Land Cover (acres( A soils BSoils Csoils DSoils Totals Forest/Open Space (acres) -- undisturbed 0'� forest/open space Managed Tuff lacresl -- disturbed, graded for 0.28 yards or other turfto be mowed/managed 0.28 Impervious Cnver(acres) 147 1.47 1.75 Post -Development Land Cover (acres( A Soils BSoils Csoils DSoils Totals Forest/Open Space(acres)-- undisturbeQ 0.00mtected forest/coor reforested land Managed Tuff (acres) - disturbed, graded for 0.95 yards or other turf to be mowed/man ed 0.95 Impervious Crver(acres) 0.80 0.80 Area Check OK. OK. OK. OK. 1.75 Pre-ReDevelopment Listed Adjusted' Forest/Open Space Cancer (acres) 0.00 0.00 Weighted Rv(fimesd 0.00 0.00 %Forest Managed Tuff Cover (acres) 0.28 0.28 Weighted Rv(turf) 0.20 0.20 %Managed Tuff 16% 16% Impervious Cover (acres) 1.47 1.47 Rv(impervious) 0.95 0.95 %Impervious 84% 84% Total She Area (acres) 1.75 1.75 she 0.v 0.83 0.83 Treatment Volume and Nutrient Load Pre-ReDevelopment Treatment Volume (acre -fit) 0.1210 0.1210 Pre-ReDevelopment Treatment Volume (cubicfeet) 5,273 5,273 Pre-ReDevelopment TP Load (Ib/yr) 3.31 3.31 PmRiDevelopmmn TP Load per acre (lb/acre/yr) 89 Baseline TP Load (IbIW) p0A1lbs/ave/yr applied to pre- redevelopment area erdudim pervious land imposed for new impervious cmreQ 072 'Adjusted Land Cover Summary: ore ReDevelopment land cover minus pervious lend cover (forenlopen spare or m raged turf) acreage proposedfor new impervious cover. adjusted total acreage is consistent with Post-ReDevelopment aaeops (minus ocreaye frewimpervimo Cowr). ^obmn I shows bad reduction requnementf rrew impervious cover (6asM on new development load limit 0.41 Ihs/ocre/year). 0.95 Post Reopen. & New Impervious ForBst/Open Space 0.00 Cover Weighted Ranorest) 0.00 %Forest 0% Managed Tuff Cover 0.95 (acres) Weighted Rv(turf) 0.20 %Managetl Turf 54% Impervious Cover 0 Rai(impervious) 0.95 %Impervious 46% Final Site Area (acres) 1.75 Final Post Den She Be 0.54 Final P.M - Development 0.0792 Treatment Volume (acre-ft) FinalPart- Development 3,449 Treatment Volume (cubicfeet) Final Post- )evelopmentTPLoad 2.17 (lb/yr) 'inal Post -development TP Lead per arm T.za (Ib/ave/yr) D Sall 0.05 0.25 0.95 Post-ReDevebpment Forest/Open Space Cover (acres) 000 Weighted Rvlforest) 0.00 %Forest 0% Managed Turf Cover (aats) 0.95 Weighted Rv (turf) 0.20 %Managed Turf 54% ReDev. Impervious Cover (acres) 080 0.v(impervious) 0.95 %Impervious 46% Tetel MO. site Area (acres) 1.75 ReDee She Be 0.54 Treatment Volume and Nutrient Load i d Reduction Required (Ib/yr) -0.48 Nitrogen Loads (Informational Purposes Only) Past-ReDevelopment TreatmentVolume 0.0792 (ecre-R) Post-ReDevelopment TreatmentVolume 3A49 (Cubk feet) Port-ReDeveopment Wad (TP) 2.17 (lb/yr)a Post-ReDevelopment TP Load per acre (lb/acre/yr) Mines. Reduction Required (Below Pre- TO% Redevelopment Load) TP Load Reduction Required for Redeveloped Area 0'48 (Ib/Yrl Final Post-Devalupmant TN load Pre-ReDevelopment TN Load(lb/yr) 23.70 (Past-ReDevelopment&New 15.50 Impervious) (b/yr) Land Cover Summary -Post Past -Development New Impervious New Impervious Cover (acres) 0.00 e Rvlimpervious) Port -Development Treatment Volume (acre it past -Development Trertmeat Volume (cubic eet) Post-DevelopmentID Wad (lb/yr) TP Load Reduction Required for New 0 .pervious Area (lb/vr)