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HomeMy WebLinkAboutWPO201700005 Agreements 2017-01-20STORMWATER MANAGEMENT REPORT Timberland Park Apartments bAlnD A[' -ID ASSOCIATES INC REFLECTING TOMORROW 1561 Commerce Road, Suite 401 Verona, VA 24482 540-248-3220 Prepared by: Kent O'Donohue, Jr. Balzer & Associates Project No: 34160034 INA.] II f) P January 4, 2017 (DKENT Y O'DONOHUE, JR.No. 0406001683 Table of Contents: INTRODUCTION.......................................................................................................................... 1 HYDROLOGIC & HYDRAULIC ANALYSIS............................................................................. 1 ExistingConditions................................................................................................................. 1 Pre-Development.................................................................................................................... 1 Table 1: Pre -developed Storm Rates.............................................................................. 1 Post-Development................................................................................................................... 2 Table 2: Post -developed Storm Rates before Detention ................................................ 2 Stormwater Quantity Management......................................................................................... 2 Table 3: Pre- to Post -Developed Storm Rates after Detention ...................................... 3 StormwaterQuality................................................................................................................. 3 AdequateChannel................................................................................................................... 3 Stormwater Conveyance Calculations.................................................................................... 3 OutletProtection..................................................................................................................... 3 Stormwater Maintenance........................................................................................................ 4 Attachments: Pre -development Calculations Page S Post -development Calculations Page 23 Water Quality Calculations Page 74 STORMWATER MANAGEMENT REPORT Timberland Park Apartments INTRODUCTION This project consists of the construction of four apartment buildings and a clubhouse. The subject parcel exists at 7.757 acres and is proposed after ROW dedication at 7.635 acres. The property is located in Albemarle County, Virginia along Old Lynchburg Road. A total of 5.5 acres will be disturbed during construction of the apartments and entrance into the property. The existing site is characterized as vacant, dense woodland. Existing slopes range from 5% to 50%. Stormwater compliance for this project is in accordance with current state regulations for a "New -development" project. (County code 17-302 and State Code 9VAC25-870-62 thru 9VAC25-870-66). This report documents the storm water design recommended by Balzer & Associates, Inc. After analysis of the site under pre and post -development conditions, a determination of the appropriate stonnwater management design was made. HYDROLOGIC & HYDRAULIC ANALYSIS Existing Conditions Currently the site topography consists of a hill with a ridge running through the middle conveying site drainage to a concrete ditch north of the property and a culvert running underneath Old Lynchburg Rd. to the south of the property. Existing slopes range from 5% to 50%. Existing ground cover consists of dense trees. Pre -Development Existing topography breaks the site in half along a ridge. The northern half of the site flows north to point of analysis, POA 1 (concrete ditch north of the property). The southern half of the site conveys water to point of analysis, POA 2 (culvert running underneath Old Lynchburg Rd.). Ground cover consists of dense woods. The enclosed Drainage Map (Sheet DA-1) illustrates the drainage areas for the site and the path of the pre -developed time of concentration. For POA 2, the 1-year flowrate is a combination of DA-B (on -site improvements) and DA-B 1 (off -site area flowing to the POA). For energy balance considerations, only the on -site area is subjected to the improvement factor. Based upon a hydrologic analysis of the site (see attached Pre -Development Calculations), the pre -development run- off rates for the identified drainage areas are as follows: Table 1: Pre -developed Storm Rates Storm Event Flowrate (cfs) DA-A POA 1 DA-B POA 2 Ql = 0.13 0.67 Q10 = 1.98 4.34 TOC = 12.4 min. 13.4 min. Stormwater Management Report Timberland Park Apartments These values were achieved using existing site contours, averaging slopes across the time of concentration lengths, and using appropriate Curve Numbers. The analysis of the pre -development run- off rates for the drainage areas was performed using Hydro -CAD® v. 10 computer software. All calculations were performed in general accordance with the TR-55 Method outlined in the Virginia Stormwater Management Handbook. Post -Development For post -development analysis, we have determined the amount of additional impervious area within the drainage areas for the currently proposed site development. Based upon a hydrologic analysis of the site (see attached Post -Development Calculations), the post -development run-off rates are as follows: Table 2: Post -developed Storm Rates before Detention Storm Event Flowrate (cfs) DA-A POA 1 DA-B POA 2 Q1 = 4.35 1.22 Q10 = 14.70 4.44 TOC = 5.0 min. 11.3 min. Due to the increase in drainage area for POA 1 and the reduction in drainage area for POA 2, the post developed flowrates before detention for POA 1 drastically increase while the flowrates for POA 2 increase, but not as significantly. Both areas will be analyzed further to meet Energy Balance and Flood Protection requirements below. Stormwater Ouantity Manazement Two Level 2 Bioretention basins with 0.5' of surface storage are proposed for stormwater quantity management for POA 1. These basins will treat runoff from Post -developed DA-Al and DA- A2, as depicted in Post -Development Drainage Map DA-2, and leave DA-A3 undetained. For POA 2, two detention pipes are proposed to treat runoff from Post -developed DA-B 1 (offsite area) and DA-B2 while leaving DA-B3 undetained. An analysis of the proposed basins and detention pipes were performed using Hydro -CAD® v. 10 computer software. The following table illustrates the reduction in run-off rates when comparing pre -development flowrates and required Energy Balance flowrates to detained post -development flowrates. Stormwater Management Report Timberland Park Apartments Table 3: Pre- to Post -Developed Storm Rates after Detention POA 1 cfs POA 2 cfs Storm Event Pre Post Energy Balance Max Pre Post Energy Balance Max Q1 = 0.13 0.01 0.01 0.67 0.56 0.60 Q10 = 1.98 1.86 - 4.34 4.34 - By providing bio-retention and detention, the post -development stormwater flowrates are below pre -developed flowrates when comparing 1-year pre -developed Energy Balance Runoff to the 1-year post -developed and pre -developed 10-year to the post -developed 10-year stormwater flowrates. Stormwater Ouality For water quality analysis, the project limits of disturbance of 5.48 acres was used to calculate phosphorus loading rates. The site is treated as a New Development. The proposed development will result in total impervious area of 2.39 acres (44%). Based on the proposed development, a total Phosphorous load reduction of 4.34 lbs P/yr is needed. To treat the stormwater quality, the proposed development includes the construction of two level 2 Bioretention Basins. Based on the existing and proposed land use of the area draining to the BMP, the basin obtains a total removal rate of 5.03 lbs P/yr, exceeding the required P removal. We have provided calculations for the water quality measures proposed for the site development (see attached Water Quality Calculations). Adequate Channel Since the Energy Balance method was used and the 10-yr post development discharge rates into the existing concrete channel (POA 1) and culvert under Old Lynchburg Rd. (POA 2) are lower than the pre developed condition the existing storm conveyance system is adequate for DA-A & B. Outlet Protection Conveyance systems discharging into the two bio-retention cells required proposed rip -rap pretreatment cells which were sized adequately for the bioretention inflow based on the Virginia Stormwater Management Handbook 2nd Edition. An outlet protection was sized to accommodate the 10-year storm event for the flow leaving the detention pipe system at the end of Storm Str #13, see attached Inlet Drainage Area Map DA-3 and Outlet Protection calculation. Stormwater Management Report Timberland Park Apartments Stormwater Maintenance Maintenance of stormwater pipes within the subject property will be the responsibility of the property owner. Maintenance of the Bioretention Basin will be the responsibility of the property owner. PRE DEVELOPMENT CALCULATIONS 100 0 100 200 300 SCALE: 1 " - 100,_ PRE DA B1 _ ✓ O 0.61 ACS -- ir' 0.24 ACS IMP.-o (NOT INCLUDED \\\� ✓ I IN WQ CALCS) IIII IililJli TOC=11.3 MIN '�'� '� '� i y✓'ter' �/ — ✓ / / I / / / / �/ �///� f r � - 'j r � ✓ %/ram= , r�� J /ram G../.r' /' \ / i— �� / � �' i% �=_�; �✓ � \ \ / �/ Y \ \ \ Fri /�--✓r^- � \ � � � � / _ /ii� j /i''i'� �,`l� �-,-F'/ / �/1/ I — \ \ \ I I ///r'�r-, �\ \ � '/' /�\/ \ 1 / //-� /i✓� � �r r /�// ,fir e✓ � �iy � �i- - � I \ \ \ 1 / /�— i/J ��/ice �i/% �_ ,✓�.''`�. �f /may rrl y// / ✓ /' �— \ I sir �✓ice �i'�� =i%i �i'� �'t T—'� Y•�T // / / /// , � �-� 1\ \ \ \ I I I/I ✓' -' '%--ii''�' ''� �-�/f•%.--. /.r �,✓� �l�- ,. Y //l ✓ i \ \ j I I I III r �- -irr-- �%; � � � � �� �.�1�✓r,r, /I / l// / / — — — \\ \ I I I I I I �I�I � \ \ � I � %% j �% i� �/j ✓r � �' t J,, j� �;'r' % l � �'_ '\ � I /� \ � l l l / // \ � \ I I I I I I I I I I I I I I /�) \ I 1 � I '' � , -J � � �.'4F��=.. �• /,, _.� " '` _ / � �l .- p � � l l l \ I I I I I / III ' \ / _� `� � �\ \ \ \\ \\ -\ �j' � \\ \\ � � ` /ram✓ /�__ \\ ,/III/ //// --�\\ \\ � \ / �\ \\\ \ / / I/I M PRE DA-B 00 ACS IMP 03.33 ACS .. � ( / _ TOC=13.4 MIN. _-----_ 'PRE DA=A - — — _ — ," I I p 2.1 5 ACS \\ .00 ACS IMP. TOC=12.4 MIN. 0% I � I // / / / '' ✓' ✓''� r ' i � /' /' I I \ \ \ \ \ \ \ \\ \ \ � \ \\ � �� �� i' / // // I I I l / l / l / � � �i, I 1 I I ✓ I f l I ✓' ✓ / \ \ \ \ \ � �� \�� \ \ ✓ / / I / 1 I I\ I 1! \�L� '✓'_'�✓'/ /_ _----''' ��'' _��''� / I I I I I 11'/ // // / / // // // /' / // '_// r / // / / ////'//' / / '/III I I `\ I / r/ _ \\�\\\\\ / / ''✓' ___- // '''/-_,^� // I I I I I I I / / / / // /' /' / / /' /r/r ��' '/ / / '/ // ' / l / ' I ( � I I 1 I I / I POA 2 Q w .balzer.cc st—ton New River Valley Roanoke Richmond Harrisonburg Balzer and Associates, Inc 128 West Market Street Suite 103 Harrisonburg, VA 22801 540-433-1908 U Q W d Z Q z F 13 m ~ Qj W W O U i QCOw ° OJ o a J w � LU m w o Q co w H Ir a DRAWN BY DKO DESIGNED BY DKO CHECKED BY WSM DATE 09-07-2016 SCALE 1•'=100' REVISIONS: 09-26-2016 ARB 12-09-2016 ISP #1 01-04-2017 WPo #1 SHEET NO. DA-1 JOB NO. 34160034 A -PS PRE bA-A ro, LI PRE POA 1 SubCat Reach on Link Routing Diagram for 2016-12-28 SWM Prepared by Microsoft, Printed 1/9/2017 HydroCAD® 10.00-14 s/n 07714 © 2015 HydroCAD Software Solutions LLC 2016-12-28 SWM Timberland Park 24-hr S1 1-yr Rainfall=3.05" Prepared by Microsoft Printed 1/9/2017 HydroCAD® 10.00-14 s/n 07714 ©2015 HydroCAD Software Solutions LLC Page 2 Time span=1.00-40.00 hrs, dt=0.01 hrs, 3901 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method SubcatchmentA-PS: PRE DA-A Runoff Area=2.150 ac 0.00% Impervious Runoff Depth=0.21" Flow Length=245' Tc=12.4 min CN=55 Runoff=0.13 cfs 0.037 of Link 1 L: PRE POA 1 Inflow=0.13 cfs 0.037 of Primary=0.13 cfs 0.037 of 2016-12-28 SWM Timberland Park 24-hr S1 1-yr Rainfall=3.05" Prepared by Microsoft Printed 1/9/2017 HydroCADO 10.00-14 s/n 07714 © 2015 HydroCAD Software Solutions LLC Page 3 Summary for Subcatchment A -PS: PRE DA-A Runoff = 0.13 cfs @ 12.55 hrs, Volume= 0.037 af, Depth= 0.21" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 1.00-40.00 hrs, dt= 0.01 hrs Timberland Park 24-hr S1 1-yr Rainfall=3.05" Area (ac) CN Description 2.150 55 Woods, Good, HSG B 2.150 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 11.4 120 0.1166 0.17 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.69" 1.0 125 0.1600 2.00 Shallow Concentrated Flow, Woodland Kv= 5.0 fDs 12.4 245 Total Subcatchment A -PS: PRE DA-A Hydrograph 0.15 0.14 0.13 cfs - 0.13 0.12 1 T I FI F I T I FI F1 1-1 1 T I TI F1 I—AaTnfa-03�015'r 0.11 0.1 1- � I �-I I � I � I �-I I � - I I �� 'i�' o�f�A77� 11b5Q ?� uno Volume= 377'a 0.09 o 0.07 Ij J- LL Tc=12.4 min 0.06 I� fil I 1 fil 111-t I -r I fil rl Irt I -t- I -rd 0.05 0.04 LU I I LI L-1 I—L - I I I i-I U 1-1 111 L U I- 0.03 Irt ICI fil r Irt1 fi Irtl fit rl Irt Irt1 fil 1i I 0.02 0.01 i- IILIL-I -tIIILLI -i - LILIAIIILILII- 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1516 17 18 19 20 21 22 23 24 25 26 27 28 29 30 3132 33 34 35 36 37 38 39 40 Time (hours) — Runoff 2016-12-28 SWM Timberland Park 24-hr S1 1-yr Rainfall=3.05" Prepared by Microsoft Printed 1/9/2017 HydroCADO 10.00-14 s/n 07714 © 2015 HydroCAD Software Solutions LLC Page 4 Summary for Link 1 L: PRE POA 1 Inflow Area = 2.150 ac, 0.00% Impervious, Inflow Depth = 0.21" for 1-yr event Inflow = 0.13 cfs @ 12.55 hrs, Volume= 0.037 of Primary = 0.13 cfs @ 12.55 hrs, Volume= 0.037 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 1.00-40.00 hrs, dt= 0.01 hrs Link 1 L: PRE POA 1 0.15 Hydrograph 0.14 0.13 14 -k I �I 0.13 I- cfs 4-1 1-4 1 I� 4 1 Area=2.1 14- L — I I - _Inflow Primary 0.12 IT T1-711-71 171FI17 nf�ow TITInI-FITITI-17 ad 0.11 0.1 �I -I 1- 14-1 1-4 1 4-I u I-� I �-I -�-I --1 1-� I 0.09 N 1-t T I t1 I-t 1 I-r I tI 11 T I - r Irt I C I fit " I rt I I o 0.07 1--[ 14-1 1-4 1 �-j I-� I�-I -�-I --1 1- LL 0.06 I-t 7-1 I-t 1 171 �1 I- rt I -rI rl Irt IT I -r-I ­1 I-T 0.05 0.04 I- 11 LI I -A 1-11 LI IA 11 E U I-1 111 LI L-1 — I-i 0.03 Irt l �l �I I-t Irt I I fil rl Irt I rtI fit r-1 1rt I 0.02 0.01 I-I1ILIUI11LI aI-iIIIIIaI-iI� — 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 : Time (hours) 2016-12-28 SWM Timberland Park 24-hr S1 10-yr Rainfall=5.58" Prepared by Microsoft Printed 1/9/2017 HydroCAD® 10.00-14 s/n 07714 ©2015 HydroCAD Software Solutions LLC Page 2 Time span=1.00-40.00 hrs, dt=0.01 hrs, 3901 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method SubcatchmentA-PS: PRE DA-A Runoff Area=2.150 ac 0.00% Impervious Runoff Depth=1.28" Flow Length=245' Tc=12.4 min CN=55 Runoff=1.98 cfs 0.230 of Link 1 L: PRE POA 1 Inflow=1.98 cfs 0.230 of Primary=1.98 cfs 0.230 of 2016-12-28 SWM Timberland Park 24-hr S1 10-yr Rainfall=5.58" Prepared by Microsoft Printed 1/9/2017 HydroCADO 10.00-14 s/n 07714 © 2015 HydroCAD Software Solutions LLC Page 3 Summary for Subcatchment A -PS: PRE DA-A Runoff = 1.98 cfs @ 12.14 hrs, Volume= 0.230 af, Depth= 1.28" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 1.00-40.00 hrs, dt= 0.01 hrs Timberland Park 24-hr S1 10-yr Rainfall=5.58" Area (ac) CN Description 2.150 55 Woods, Good, HSG B 2.150 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 11.4 120 0.1166 0.17 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.69" 1.0 125 0.1600 2.00 Shallow Concentrated Flow, Woodland Kv= 5.0 fDs 12.4 245 Total U 0 LL Subcatchment A -PS: PRE DA-A Hydrograph 1.98 cfs 4irhbe�l�nd Park 24I-hIr s1 10I yr Rainfall�5.58" Runoff�11 lAlrea- .150 a Runowolu"= 230� a� Runoff Pepth=1.281' Floen th=2451' c� 2141 rn ¢N=55 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 Time (hours) — Runoff 2016-12-28 SWM Timberland Park 24-hr S1 10-yr Rainfall=5.58" Prepared by Microsoft Printed 1/9/2017 HydroCAD® 10.00-14 s/n 07714 ©2015 HydroCAD Software Solutions LLC Page 4 Summary for Link 1 L: PRE POA 1 Inflow Area = 2.150 ac, 0.00% Impervious, Inflow Depth = 1.28" for 10-yr event Inflow = 1.98 cfs @ 12.14 hrs, Volume= 0.230 of Primary = 1.98 cfs @ 12.14 hrs, Volume= 0.230 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 1.00-40.00 hrs, dt= 0.01 hrs Link 1 L: PRE POA 1 Hydrograph 1.98 cfs Inflow lArea l=2.1150 ac y IIIIIIIIII I �lilll ili�lllllllll w U. 1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 41 Time (hours) — Inflow -111 — Primary B-PS : 1 :4 a M •1 � Subcat Reach on Link Bl-PS wMall'allooll 2016-12-28 SWM Timberland Park 24-hr S1 1-yr Rainfall=3.05" Prepared by Microsoft Printed 1/10/2017 HydroCAD® 10.00-14 s/n 07714 ©2015 HydroCAD Software Solutions LLC Page 2 Time span=1.00-40.00 hrs, dt=0.01 hrs, 3901 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method SubcatchmentB-PS: PRE DA-B Runoff Area=3.330 ac 0.00% Impervious Runoff Depth=0.21" Flow Length=315' Tc=13.4 min CN=55 Runoff=0.21 cfs 0.058 of SubcatchmentB1-PS: PRE DA-B1 Runoff Area=0.610 ac 39.34% Impervious Runoff Depth=0.84" Flow Length=719' Tc=11.3 min CN=72 Runoff=0.46 cfs 0.043 of 2016-12-28 SWM Timberland Park 24-hr S1 1-yr Rainfall=3.05" Prepared by Microsoft Printed 1/10/2017 HydroCAD®10.00-14 s/n 07714 ©2015 HydroCAD Software Solutions LLC Page 3 Summary for Subcatchment B-PS: PRE DA-B Runoff = 0.21 cfs @ 12.55 hrs, Volume= 0.058 af, Depth= 0.21" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 1.00-40.00 hrs, dt= 0.01 hrs Timberland Park 24-hr S1 1-yr Rainfall=3.05" Area (ac) CN Description 3.330 55 Woods, Good, HSG B 3.330 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 11.8 120 0.1083 0.17 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.69" 1.6 195 0.1640 2.02 Shallow Concentrated Flow, Woodland Kv= 5.0 fDs 13.4 315 Total Subcatchment B-PS: PRE DA-B Hydrograph 0.23 0.22 0.0.1 0.21 cfs -Runoff 0.2 H �I I 1 4-1 HI 1 1 -� �i"�-An""rk 2�- ir41 "� 0.18 14 I H I HI H 1+ 1 HI H IH 1+ 1 HI H IHFWnfc-003�G$'r 0.17 0.16 0.15 Znno"�=3�O 'Vduia 0.14 w 0.13 H HI H IH T- I� I H I::[I T- I HI � rioIff I DT Oth�OF2H'I 0.11 H IH1 H H1H1 H H14 1+ 0 0.1 U=1-3�4-min 0.09 1H IHI H HIH1 H H H It H H H 1HI 0.08 0.0 0.06 I�I11LH I IDH11111LIH111H1EH 0.05 0.04 I W II 1-1-1HIH141H14-IHI 0.03 0.02 1-+IHIHIH HIHHHIHI IHIHIHIHIHIHI 0.01 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1516 17 1819 20 21 22 23 24 25 26 27 28 29 30 3132 33 34 35 36 37 38 39 40 Time (hours) 2016-12-28 SWM Timberland Park 24-hr S1 1-yr Rainfall=3.05" Prepared by Microsoft Printed 1/10/2017 HydroCAD®10.00-14 s/n 07714 ©2015 HydroCAD Software Solutions LLC Page 4 Summary for Subcatchment B1-PS: PRE DA-B1 Runoff = 0.46 cfs @ 12.12 hrs, Volume= 0.043 af, Depth= 0.84" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 1.00-40.00 hrs, dt= 0.01 hrs Timberland Park 24-hr S1 1-yr Rainfall=3.05" Area (ac) CN Description 0.370 55 Woods, Good, HSG B 0.240 98 Paved roads w/curbs & sewers, HSG B 0.610 72 Weighted Average 0.370 60.66% Pervious Area 0.240 39.34% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 4.8 35 0.0850 0.12 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.69" 2.1 154 0.0580 1.20 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 4.4 530 0.0100 2.03 Shallow Concentrated Flow, Paved Kv= 20.3 fas 11.3 719 Total Subcatchment B1-PS: PRE DA-B1 Hydrograph - - I - I — I — — - �I _Runoff 0.46 cfs I l 1 T I �I H "Ti"Waa1n""r 2�- ir�ll 1 H I H 1 HI H I I HI H IH I H I HI H I�-Rla�nf a 3�0{5'r I-T I T I �I H I �I H 1� I 1 w H H I H H 1 H 1 HI H IH It H �AO*IDeoth�Ot O 028 0 0.2a 0.22 3 �n1 0.2 1HIt1 I� 1HI H 1 f I—tItI�I H I—tI+Itd�� 0.18 0.16 0.14 I� TI I �I I 14 TI H I� �I H 0.12 0.1 1� I t I tI H I t I t1 H I� I t I fit H 1� It I tl H I 0.08 00 0.04 I4I�I H IH I-� I H IH I-4I-�I�-I H I-4I-�I4-I H 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 Time (hours) J PRE DA- B1-PS ,,XRRE DA-B1 POA2-PS PRE POA 2 Subcat Reach on Link 2016-12-28 SWM Timberland Park 24-hr S1 10-yr Rainfall=5.58" Prepared by Microsoft Printed 1/10/2017 HydroCAD® 10.00-14 s/n 07714 ©2015 HydroCAD Software Solutions LLC Page 2 Time span=1.00-40.00 hrs, dt=0.01 hrs, 3901 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method SubcatchmentB-PS: PRE DA-B Runoff Area=3.330 ac 0.00% Impervious Runoff Depth=1.28" Flow Length=315' Tc=13.4 min CN=55 Runoff=2.97 cfs 0.356 of SubcatchmentB1-PS: PRE DA-B1 Runoff Area=0.610 ac 39.34% Impervious Runoff Depth=2.65" Flow Length=719' Tc=11.3 min CN=72 Runoff=1.46 cfs 0.135 of Link POA2-PS: PRE POA 2 Inflow=4.34 cfs 0.491 of Primary=4.34 cfs 0.491 of 2016-12-28 SWM Timberland Park 24-hr S1 10-yr Rainfall=5.58" Prepared by Microsoft Printed 1/10/2017 HydroCAD®10.00-14 s/n 07714 ©2015 HydroCAD Software Solutions LLC Page 3 Summary for Subcatchment B-PS: PRE DA-B Runoff = 2.97 cfs @ 12.16 hrs, Volume= 0.356 af, Depth= 1.28" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 1.00-40.00 hrs, dt= 0.01 hrs Timberland Park 24-hr S1 10-yr Rainfall=5.58" Area (ac) CN Description 3.330 55 Woods, Good, HSG B 3.330 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 11.8 120 0.1083 0.17 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.69" 1.6 195 0.1640 2.02 Shallow Concentrated Flow, Woodland Kv= 5.0 fDs 13.4 315 Total U 0 LL Subcatchment B-PS: PRE DA-B Hydrograph 11MIM II11111111111111 2.97 cfs IT ITI T TI -I I T 1 TI T irhbe�i�nd IPark �� hr�1 �oly� Rainfall�5.58" IIIIIIIII JJ RZ I Area aa�v�WoAu6-0.36 T I T I T1 I T I TI T I—F T I TR4"ff-P� J"�87- III 1 1 1 1 1 1 1 1 1 1 F11 v7 �nth=31 5'34mi IIIII IIIIIIIIIIIIIIIIIIIII9N=55 IT ITITI TIT fit T IrtTITI TIT ITITIT IIIIIIIII IIIIIIIIIIIIIIIIIIIIIIIIII IIMil 1111 IIII1111'11 m III I 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 Time (hours) — Runoff 2016-12-28 SWM Timberland Park 24-hr S1 10-yr Rainfall=5.58" Prepared by Microsoft Printed 1/10/2017 HydroCAD®10.00-14 s/n 07714 ©2015 HydroCAD Software Solutions LLC Page 4 Summary for Subcatchment B1-PS: PRE DA-B1 Runoff = 1.46 cfs @ 12.11 hrs, Volume= 0.135 af, Depth= 2.65" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 1.00-40.00 hrs, dt= 0.01 hrs Timberland Park 24-hr S1 10-yr Rainfall=5.58" Area (ac) CN Description 0.370 55 Woods, Good, HSG B 0.240 98 Paved roads w/curbs & sewers, HSG B 0.610 72 Weighted Average 0.370 60.66% Pervious Area 0.240 39.34% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 4.8 35 0.0850 0.12 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.69" 2.1 154 0.0580 1.20 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 4.4 530 0.0100 2.03 Shallow Concentrated Flow, Paved Kv= 20.3 fas 11.3 719 Total N w 0 LL Subcatchment B1-PS: PRE DA-B1 Hydrograph III IIIIIIIII it IIII 1.46 cfs 41me�rl�nd (Park 241-Hr S� �O yr Rainfall�5.581' I I I I� R�npff Area o.s1 o ac uhh 4 Volumb-0 1 15l ai Runoff Pdpi h�2.651' " Ipvr en7t =719' 1 3 rri i� 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 41 Time (hours) — Runoff 2016-12-28 SWM Timberland Park 24-hr S1 10-yr Rainfall=5.58" Prepared by Microsoft Printed 1/10/2017 HydroCAD® 10.00-14 s/n 07714 ©2015 HydroCAD Software Solutions LLC Page 5 Summary for Link POA2-PS: PRE POA 2 Inflow Area = 3.940 ac, 6.09% Impervious, Inflow Depth = 1.49" for 10-yr event Inflow = 4.34 cfs @ 12.14 hrs, Volume= 0.491 of Primary = 4.34 cfs @ 12.14 hrs, Volume= 0.491 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 1.00-40.00 hrs, dt= 0.01 hrs Link POA2-PS: PRE POA 2 Hydrograph 4.34 cfs 11 1 1 1 I IIIIIWIin�wl',�e A= .1- 40 lIIIII 11111111111111111111111111I J-1 I T I T I TI T T I TI T IT IT' TI 7' IT IT TI TI 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 41 Time (hours) — Inflow -111 — Primary POST DEVELOPMENT CALCULATIONS N M 100 0 100 200 300 \\ L SCALE; 1 " - 100' _= POST DA-61- �i 0.61 ACS--- 0.24 ACS IMP.-_— \ 1j1\\\\\\\\\° %'- - (NOT INCLUDED `� \\�\`\ \I I' , K _ ' IN WQ CALCS) \ Illl lilli)II -- TOC=111.3 MIN.- GG // /�i � J, � \ � �' �_,� A/ I �� f/�i� �i/i /ice'•'—_• ! �' \ POA 1 POST DA-B2 — / / �� \ \� /' r/, i� ` �' y✓i y%' 0.85 ACS " 0.23 ACS IMP. -- C� / / —--I%�✓--! '—G FIFO /`�✓,✓tip lO Ll 0.04 ACS 0.00 ACS I_P_.` \ \ I \\ \ /\ \ \ \ \ �I I POST DA-A2 2.32 ACS E T�;�.�\\\\\ \\il i'II 11,/ / -- �\� --- - --- 1.30 ACS IMP. \ I �'I POST DA-Al 1.85 ACS ACS IMP. \\ 0.42 ACS I I 1 / / // /'' �/''�✓''� i _� / I I 1 1 1 1 rl / oe \ \� / ° oe 0.00 ACS IMP. G I i I I\ I L� ' '' ✓'� i��_--''�,,✓' _,,,-�/ I I I I I I � 1 / � / I � POA 2 A I w .balzer.cc stauaton New River Valley Roanoke Richmond Harrisonburg Balzer and Associates, Inc 128 West Market Street Suite 103 Harrisonburg, VA 22801 540-433-1908 a U)LLJ G V d Q a Z Q U o u d= Z - 5 �= w 0 U Z zo 5-H w Q o _j 0 < > ") m w w a m o � H 0 d DRAWN BY DKO DESIGNED BY DKO CHECKED BY WSM DATE 09-07-2016 SCALE 1"=100' REVISIONS- 09-26-2016 ARB 12-09-2016 ISP #1 01-04-2017 WPO #1 SHEET NO. DA-2 JOB NO. 34160034 Project: Timberland Park Apmts Drainage Area: DA-A Project #: 34160034 Date 12/29/2016 Drainage Area A: Total Disturbed Area: 4.21 acres 1 Year RVpre-Developed 0.04 of RVDeveloped 0.29 of Improvement Factor I.F. 0.80 QPre-Developed 0.13 cfs Energy Balance Equation: QDeveloped < I.F.*(QPre-Developed* RVPre-DevelopedYwDeveloped Maximum QDeveloped to meet Energy Equation: I0.01 cfs * From HydroCAD * From HydroCAD * Disturbed Area Exceeds 1 Acre * From HydroCAD * Equation from 9VAC25-870-66, Section B. 3. Actual QDeveloped 0.01 cfs * From HydroCAD Meets Channel Protection Requirements A2-P A2-1 YR _D Al-P POST DA-Al BIO 2 POST DA-A2 BIO 1 A-R �A3-S POST DA-A3 POST POA 1 (30" CMP) Subcat Reach on Link 2016-12-28 SWM Timberland Park 24-hr S1 1-yr Rainfall=3.05" Prepared by Microsoft Printed 1/9/2017 HvdroCAD® 10.00-14 s/n 07714 ©2015 HvdroCAD Software Solutions LLC Paae 2 Time span=1.00-40.00 hrs, dt=0.01 hrs, 3901 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method SubcatchmentA1-lYR: POST DA-Al Runoff Area=1.850 ac 0.00% Impervious Runoff Depth=0.74" Tc=5.0 min CN=70 Runoff=1.59 cfs 0.114 of SubcatchmentA2-1YR: POST DA-A2 Runoff Area=2.320 ac 0.00% Impervious Runoff Depth=0.94" Tc=5.0 min CN=74 Runoff=2.74 cfs 0.182 of SubcatchmentA3-S: POST DA-A3 Runoff Area=0.040 ac 0.00% Impervious Runoff Depth=0.38" Tc=5.0 min CN=61 Runoff=0.01 cfs 0.001 of Reach A-R: POST POA 1 (30" CMP) Inflow=0.01 cfs 0.002 of Outflow=0.01 cfs 0.002 of Pond Al-P: BIO 1 Peak Elev=434.24' Storage=4,984 cf Inflow=1.59 cfs 0.114 of Outflow=0.00 cfs 0.000 of Pond A2-P: BIO 2 Peak Elev=422.51' Storage=7,916 cf Inflow=2.74 cfs 0.182 of Outflow=0.00 cfs 0.001 of 2016-12-28 SWM Timberland Park 24-hr S1 1-yr Rainfall=3.05" Prepared by Microsoft Printed 1/9/2017 HydroCADO 10.00-14 s/n 07714 © 2015 HydroCAD Software Solutions LLC Page 3 Summary for Subcatchment Al-1YR: POST DA-Al Runoff = 1.59 cfs @ 12.04 hrs, Volume= 0.114 af, Depth= 0.74" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 1.00-40.00 hrs, dt= 0.01 hrs Timberland Park 24-hr S1 1-yr Rainfall=3.05" Area (ac) CN Description 1.850 70 CN FROM RR SPREADSHEET 1.850 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, w 0 LL Subcatchment A1-1YR: POST DA-Al Hydrograph 1.59 cfs Tirdble�I�nd (Pork 24-f rlSll 1 �y� l l l l l l l l l I I I Rkainfa11=�3A'5'r Runoff,q� rea=1. 50 a c uno Volume=6.i 4'a u Li II IR6"ffbe �OlNl - i � Try=5�0�rr�ir� 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 41 Time (hours) — Runoff 2016-12-28 SWM Timberland Park 24-hr S1 1-yr Rainfall=3.05" Prepared by Microsoft Printed 1/9/2017 HydroCADO 10.00-14 s/n 07714 © 2015 HydroCAD Software Solutions LLC Page 4 Summary for Subcatchment A2-1YR: POST DA-A2 Runoff = 2.74 cfs @ 12.03 hrs, Volume= 0.182 af, Depth= 0.94" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 1.00-40.00 hrs, dt= 0.01 hrs Timberland Park 24-hr S1 1-yr Rainfall=3.05" Area (ac) CN Description 2.320 74 CN FROM RR SPREADSHEET 2.320 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Subcatchment A2-1YR: POST DA-A2 Hydrograph w 0 LL 3 + 2.74 cfs l Tirdble�I�nd IPark 24-f rlSl1 1 �y� I I I Rkainfa11=�3A'5'r Ru� �off rea 2.1 2ac�- III I I IR6660 deoth�O1.914'� Try=5�0 rr�iq IIIIIII � �IIIIIIIIIIIIIIIIIIIIIII IIIIIIIIII �IIIIIIIIIIIIIIIIIIIIIIIIII IIIII Illlllllllllllillllll'Illll � ��� II'IlIllIll IIIII III II 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 41 Time (hours) — Runoff 2016-12-28 SWM Timberland Park 24-hr S1 1-yr Rainfall=3.05" Prepared by Microsoft Printed 1/9/2017 HydroCADO 10.00-14 s/n 07714 © 2015 HydroCAD Software Solutions LLC Page 5 Summary for Subcatchment A3-S: POST DA-A3 Runoff = 0.01 cfs @ 12.05 hrs, Volume= 0.001 af, Depth= 0.38" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 1.00-40.00 hrs, dt= 0.01 hrs Timberland Park 24-hr S1 1-yr Rainfall=3.05" Area (ac) CN Description 0.040 61 >75% Grass cover, Good, HSG B 0.040 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Subcatchment A3-S: POST DA-A3 Hydrograph 0.011 0.01 0.01 - cfs 0.01 - - H H— H— �ii>1�r�n�a�r1�-Iir �1 14� 00.09 — 0.009 Irt �I tj I-T rt fil 1-1 Irt I rt I fil rl Irt JR4i"n aP3�015'r 0.008 0.008 0.007 1-11 � F] 1l I- D I -I I T I TIRF�W,r bib uno ume- a 0.007 w 0.006 141 �- I 1-4 14 1 �- I �I k-� "riot# DIe0th401.*1 0.006 0 0.005 1-� I +I H 1- -1 H 1-+ 1+1 -I H 1- +1 LL 0.005 0.004 Irt l I fi t 1-1 Irt I l Irt I l -I I— Irt l 0.004 — —Irt — — — — 0.003 0.003 El El 11 I CI El la IT I LI 11 11 I 1: 1 :EI IA 111 0.002 0.002 I � 1 4-I 14 1 1 �I k-� 14 I �- I �-I 1-4 141- 0.001 0.001 1-+1�I H I-- +I �I �I H 1-+ I+1 H H 1-+I 0.000 0 1 2 3 4 5 6 7 8 9 1011 1213 14 15 16 17 18 19 20 2122 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 Time (hours) — Runoff 2016-12-28 SWM Timberland Park 24-hr S1 1-yr Rainfall=3.05" Prepared by Microsoft Printed 1/9/2017 HydroCADO 10.00-14 s/n 07714 © 2015 HydroCAD Software Solutions LLC Page 6 Summary for Reach A-R: POST POA 1 (30" CMP) Inflow Area = 4.210 ac, 0.00% Impervious, Inflow Depth > 0.01" for 1-yr event Inflow = 0.01 cfs @ 12.05 hrs, Volume= 0.002 of Outflow = 0.01 cfs @ 12.05 hrs, Volume= 0.002 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 1.00-40.00 hrs, dt= 0.01 hrs Reach A-R: POST POA 1 Hydrograph (30" CMP) 0.011 0.01 0.01 cfs —: 0.01 1� I -HH I� + 1 �1 H + I. H I-+ I + I -H _Inflow Outflow 0009 Inflo Ai a-c 0.009 rtlfil r1 Irt �I fil rt IrtIfiI fit Irt ICI fil rt IrtIfi 0.008 0.008 1-L1L1 L I-1 11 LI Ll 111L1 L II III L Ll I 1 1 L 1 0.007 0.007 ,0.006 — — 1414-It-1I4 — — — �-1�1-4414-I�-]I41�-1�I-4414-1 — — — — — — — — — — — 0.006 0 0.005 1-�I- H I-1- 1 -1 H I+I- H I-+ I+I -I H I+I- 1 LL 0.005 0.004 1rtItI fit Irt I fit H I t I t l fit Irt I t I tl H ItIfi1 0.004 0.003 ITID El I- :71 1-1 ITID El -IITI:I 1-1 ITITI 0.003 0.002 0.002 1414-1 �-] I4 14--1 -4 414-1 1�-14--I -! � I I � 0.001 - 0.001 1-� I -I H I—+ +1 H H 0.000 0 1 2 3 4 5 6 7 8 9 1011 12 13 14 15 16 17 18 19 20 2122 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 Time (hours) 2016-12-28 SWM Timberland Park 24-hr S1 1-yr Rainfall=3.05" Prepared by Microsoft Printed 1/9/2017 HydroCAD® 10.00-14 s/n 07714 ©2015 HydroCAD Software Solutions LLC Page 7 Summary for Pond Al-P: B10 1 Inflow Area = 1.850 ac, 0.00% Impervious, Inflow Depth = 0.74" for 1-yr event Inflow = 1.59 cfs @ 12.04 hrs, Volume= 0.114 of Outflow = 0.00 cfs @ 1.00 hrs, Volume= 0.000 af, Atten= 100%, Lag= 0.0 min Primary = 0.00 cfs @ 1.00 hrs, Volume= 0.000 of Routing by Stor-Ind method, Time Span= 1.00-40.00 hrs, dt= 0.01 hrs Peak Elev= 434.24' @ 24.29 hrs Surf.Area= 3,042 sf Storage= 4,984 cf Plug -Flow detention time= (not calculated: initial storage exceeds outflow) Center -of -Mass det. time= (not calculated: no outflow) Volume Invert Avail.Storage Storage Description #1 427.67' 12,974 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Voids Inc.Store Cum.Store (feet) (sq-ft) (%) (cubic -feet) (cubic -feet) 427.67 1,795 0.0 0 0 431.00 1,795 40.0 2,391 2,391 432.50 1,795 40.0 1,077 3,468 434.00 2,627 25.0 829 4,297 436.00 6,050 100.0 8,677 12,974 Device Routing Invert Outlet Devices #1 Primary 434.50' Custom Weir/Orifice, Cv= 2.62 (C= 3.28) Head (feet) 0.00 0.80 0.80 1.30 Width (feet) 0.25 0.25 8.00 8.00 Primary OutFlow Max=0.00 cfs @ 1.00 hrs HW=427.67' (Free Discharge) L1=Custom Weir/Orifice ( Controls 0.00 cfs) 2016-12-28 SWM Timberland Park 24-hr S1 1-yr Rainfall=3.05" Prepared by Microsoft Printed 1/9/2017 HydroCADO 10.00-14 s/n 07714 © 2015 HydroCAD Software Solutions LLC Page 8 w 1 u 3 0 LL 1.59 cfs -L I II LI U Pond Al-P: BIO 1 Hydrograph I I I I I I I I I I I I I I I III in, f io, w real =1I.ac 1 1 l u l l Leak L1ev I41314I.Z4' IIIIIIIIIII II wI '.II torage=4,984 cf Li I I LI U II I -LI q 0.00 cfs 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 Time (hours) — Inflow — Primary 2016-12-28 SWM Timberland Park 24-hr S1 1-yr Rainfall=3.05" Prepared by Microsoft Printed 1/9/2017 HydroCAD® 10.00-14 s/n 07714 ©2015 HydroCAD Software Solutions LLC Page 9 Summary for Pond A2-P: B10 2 Inflow Area = 2.320 ac, 0.00% Impervious, Inflow Depth = 0.94" for 1-yr event Inflow = 2.74 cfs @ 12.03 hrs, Volume= 0.182 of Outflow = 0.00 cfs @ 24.16 hrs, Volume= 0.001 af, Atten= 100%, Lag= 727.6 min Primary = 0.00 cfs @ 24.16 hrs, Volume= 0.001 of Routing by Stor-Ind method, Time Span= 1.00-40.00 hrs, dt= 0.01 hrs Peak Elev= 422.51' @ 24.16 hrs Surf.Area= 4,675 sf Storage= 7,916 cf Plug -Flow detention time= 1,040.4 min calculated for 0.001 of (0% of inflow) Center -of -Mass det. time= 820.6 min ( 1,702.6 - 882.0 ) Volume Invert Avail.Storage Storage Description #1 416.67' 15,880 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Voids Inc.Store Cum.Store (feet) (sq-ft) (%) (cubic -feet) (cubic -feet) 416.67 3,212 0.0 0 0 419.00 3,212 40.0 2,994 2,994 420.00 3,212 25.0 803 3,797 422.00 4,224 25.0 1,859 5,656 424.00 6,000 100.0 10,224 15,880 Device Routing Invert Outlet Devices #1 Primary 422.50' Custom Weir/Orifice, Cv= 2.62 (C= 3.28) Head (feet) 0.00 1.00 1.00 1.50 Width (feet) 0.42 0.42 16.00 16.00 Primary OutFlow Max=0.00 cfs @ 24.16 hrs HW=422.51' (Free Discharge) L1=Custom Weir/Orifice (Weir Controls 0.00 cfs @ 0.29 fps) 2016-12-28 SWM Timberland Park 24-hr S1 1-yr Rainfall=3.05" Prepared by Microsoft Printed 1/9/2017 HydroCADO 10.00-14 s/n 07714 © 2015 HydroCAD Software Solutions LLC Page 10 Pond A2-P: BIO 2 Hydrograph 3 0 LL it an Ci � I +—I h I—f I + +—I 2.74 cfs io, in,fwlAreal 121.3Z0 ac ' IIIIIIIIIIII III IIIIII , eak ev=422. I I I�ohl II I �19I� �� f. IIIII IIIIIIIIIIIIII07r="�IIII 11IIIII IIIIIIIIIIIIIIIIIIIIIIII1WI 0.00 cfs 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 Time (hours) — Inflow — Primary Al-10YR A2-10YR POST A -Al POST DA-A2 XA2-P Al-P BIO 2 BIO 1 A3-S A- R POST DA-A3 POST POA 1 (30" CMP) Subcat Reach on Link 2016-12-28 SWM Timberland Park 24-hr S1 10-yr Rainfall=5.58" Prepared by Microsoft Printed 1/9/2017 HvdroCAD® 10.00-14 s/n 07714 ©2015 HvdroCAD Software Solutions LLC Paae 2 Time span=1.00-40.00 hrs, dt=0.01 hrs, 3901 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method SubcatchmentA1-10YR: POST DA-Al Runoff Area=1.850 ac 0.00% Impervious Runoff Depth=2.74" Tc=5.0 min CN=73 Runoff=6.01 cfs 0.423 of SubcatchmentA2-10YR: POST DA-A2 Runoff Area=2.320 ac 0.00% Impervious Runoff Depth=3.12" Tc=5.0 min CN=77 Runoff=8.61 cfs 0.602 of SubcatchmentA3-S: POST DA-A3 Runoff Area=0.040 ac 0.00% Impervious Runoff Depth=1.73" Tc=5.0 min CN=61 Runoff=0.08 cfs 0.006 of Reach A-R: POST POA 1 (30" CMP) Inflow=1.86 cfs 0.715 of Outflow=1.86 cfs 0.715 of Pond Al-P: BIO 1 Peak EIev=435.30' Storage=9,172 cf Inflow=6.01 cfs 0.423 of Outflow=0.60 cfs 0.289 of Pond A2-P: BIO 2 Peak EIev=423.46' Storage=12,743 cf Inflow=8.61 cfs 0.602 of Outflow=1.29 cfs 0.421 of 2016-12-28 SWM Timberland Park 24-hr S1 10-yr Rainfall=5.58" Prepared by Microsoft Printed 1/9/2017 HydroCADO 10.00-14 s/n 07714 © 2015 HydroCAD Software Solutions LLC Page 3 Summary for Subcatchment Al-10YR: POST DA-Al Runoff = 6.01 cfs @ 12.03 hrs, Volume= 0.423 af, Depth= 2.74" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 1.00-40.00 hrs, dt= 0.01 hrs Timberland Park 24-hr S1 10-yr Rainfall=5.58" Area (ac) CN Description 1.850 73 CN FROM RR SPREADSHEET 1.850 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, N w 0 LL Subcatchment Al-10YR: POST DA-Al Hydrograph III 6.01 cfs rt fil 1� Irt �I 4irh e 1� n IP"rk:�4T.lir1 01y� IIIIIIII IIIIIIIIH Roiofoii�4.§81' IIIIIIII Z Volu�l 0.4�31 a� ITc=5.0_I_ min1 �� 73 I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I rt Itl ' � I- I fit N Irt I t I fit H II Irt I t I fi IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII I I I I I I I I l l l i l l B i l l I WI 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 4i Time (hours) — Runoff 2016-12-28 SWM Timberland Park 24-hr S1 10-yr Rainfall=5.58" Prepared by Microsoft Printed 1/9/2017 HydroCADO 10.00-14 s/n 07714 © 2015 HydroCAD Software Solutions LLC Page 4 Summary for Subcatchment A2-10YR: POST DA-A2 Runoff = 8.61 cfs @ 12.03 hrs, Volume= 0.602 af, Depth= 3.12" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 1.00-40.00 hrs, dt= 0.01 hrs Timberland Park 24-hr S1 10-yr Rainfall=5.58" Area (ac) CN Description 2.320 77 CN FROM RR SPREADSHEET 2.320 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, w 0 LL Subcatchment A2-10YR: POST DA-A2 Hydrograph IIIII III II, I I Will 8.61 cfs — — i�nl�eYJ�ri�P�rk24-Hr-�1101y uhd IIIII IC�I IIIII Rff Vol 60 6621 a� — I I I I I F qnpff PWh�J.1121' IIIII T�5.O-min- 6r =71 11111111 111111111111111111111111111 I T I P F1 7ITI TI 7 17 ITI 1 1-1 1 1 17I 7 1 T 7 171 T1 71 1 I71TI TI 7 I7 TI T TI 17 17 71 T 7 ITI T" 1 7 I7 7 7 7 ITI 7 1 17 17 ITI T 7 8 9 10 11 12 13 14 15 16 17 18 19 2021 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 41 Time (hours) — Runoff 2016-12-28 SWM Timberland Park 24-hr S1 10-yr Rainfall=5.58" Prepared by Microsoft Printed 1/9/2017 HydroCADO 10.00-14 s/n 07714 © 2015 HydroCAD Software Solutions LLC Page 5 Summary for Subcatchment A3-S: POST DA-A3 Runoff = 0.08 cfs @ 12.03 hrs, Volume= 0.006 af, Depth= 1.73" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 1.00-40.00 hrs, dt= 0.01 hrs Timberland Park 24-hr S1 10-yr Rainfall=5.58" Area (ac) CN Description 0.040 61 >75% Grass cover, Good, HSG B 0.040 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Subcatchment A3-S: POST DA-A3 Hydrograph 0.08 — — — 0.08 cfs 0.075 1� t t I t' 1� 0.07 0.065 — 4 1 -k t-I 14 4 — �-I 14 T 1 4- 1 b -k-1 Ian r 4—h k 1--� I _kRa0f 4J"T I I I I I I I I I I I I I II�r4b0 �ac� 0.055 0.05 1-t I t t� 1-t t t f1 1-t I t I t1 Ii�u"f# Wep 11 .-T31, 0.045 g 0.04 141 � I �-d I� 1-4- 4-1 14 1 1 4--1� -C=SO �n 14 1 �I 1U. -�� � 0.035 0.03 1111111111 111111111111111111111111111 0.025 1 rt t l 1-I 11 fit " 11 1 t I fit " I I t I t—I 1—t I —t1 0.02 0.015 I�1-I � 14 -kI � 14 14-1 �I k 14I-kI �I IA 141 0.01 0.005 IIIIIIIIIII IIIIIIIIIIIIIIIIIIIIIIIII 1 12 13 14 15 16 17 18 19 20 2122 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 Time (hours) — Runoff 2016-12-28 SWM Timberland Park 24-hr S1 10-yr Rainfall=5.58" Prepared by Microsoft Printed 1/9/2017 HydroCADO 10.00-14 s/n 07714 © 2015 HydroCAD Software Solutions LLC Page 6 Summary for Reach A-R: POST POA 1 (30" CMP) Inflow Area = 4.210 ac, 0.00% Impervious, Inflow Depth > 2.04" for 10-yr event Inflow = 1.86 cfs @ 12.63 hrs, Volume= 0.715 of Outflow = 1.86 cfs @ 12.63 hrs, Volume= 0.715 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 1.00-40.00 hrs, dt= 0.01 hrs w 3 0 LL Reach A-R: POST POA 1 (30" CMP) Hydrograph 1.86 cfs .I 1 111 IIIIIII intlowlAr- I41.Z'10 acl I11111 IIIIIIIIIIIIIIIIIIIIIIIIII i l l l IM U 11 l l l l l l l l IM 1 1 l l l IM I IIIIIIIIIII IIIIIIIIIIIIIIIIIIIIIIIII F IHIHIHI HI 141 1�- I H 1H1H14-I HI H HIHH I II IIII11111111111111111111111111111111 IIIIII11111111I 1111111111111111111111 II 111111111111111 111111111111111111 IIIIIIIIII II1111111111 III11111111111 J 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 Time (hours) Inflow Outflow 2016-12-28 SWM Timberland Park 24-hr S1 10-yr Rainfall=5.58" Prepared by Microsoft Printed 1/9/2017 HydroCAD® 10.00-14 s/n 07714 ©2015 HydroCAD Software Solutions LLC Page 7 Summary for Pond Al-P: B10 1 Inflow Area = 1.850 ac, 0.00% Impervious, Inflow Depth = 2.74" for 10-yr event Inflow = 6.01 cfs @ 12.03 hrs, Volume= 0.423 of Outflow = 0.60 cfs @ 12.89 hrs, Volume= 0.289 af, Atten= 90%, Lag= 51.8 min Primary = 0.60 cfs @ 12.89 hrs, Volume= 0.289 of Routing by Stor-Ind method, Time Span= 1.00-40.00 hrs, dt= 0.01 hrs Peak Elev= 435.30' @ 12.89 hrs Surf.Area= 4,857 sf Storage= 9,172 cf Plug -Flow detention time= 305.6 min calculated for 0.289 of (68% of inflow) Center -of -Mass det. time= 188.4 min ( 1,039.1 - 850.8 ) Volume Invert Avail.Storage Storage Description #1 427.67' 12,974 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Voids Inc.Store Cum.Store (feet) (sq-ft) (%) (cubic -feet) (cubic -feet) 427.67 1,795 0.0 0 0 431.00 1,795 40.0 2,391 2,391 432.50 1,795 40.0 1,077 3,468 434.00 2,627 25.0 829 4,297 436.00 6,050 100.0 8,677 12,974 Device Routing Invert Outlet Devices #1 Primary 434.50' Custom Weir/Orifice, Cv= 2.62 (C= 3.28) Head (feet) 0.00 0.80 0.80 1.30 Width (feet) 0.25 0.25 8.00 8.00 Primary OutFlow Max=0.59 cfs @ 12.89 hrs HW=435.30' (Free Discharge) L1=Custom Weir/Orifice (Weir Controls 0.59 cfs @ 2.66 fps) 2016-12-28 SWM Timberland Park 24-hr S1 10-yr Rainfall=5.58" Prepared by Microsoft Printed 1/9/2017 HydroCADO 10.00-14 s/n 07714 © 2015 HydroCAD Software Solutions LLC Page 8 3 0 LL Pond Al -P: BIO 1 Hydrograph 1 1 1 6.01 cfs rt l rt l fil I —I rtI�ntlowlArE I I I I I I 11 I I II I I I _I I I IIIIIIII I�torai rtlrtlfil � rtl i Ifil � Irtlrtlfil �' ' Irt It fil ri IVIt1 fit �-1 Irt It fit " "I- fit rI IIIIII III I16Icf11IIIIIIIIIIIIIIIIIIIIIII IIIIIIIIII IIIIIIIIIIIIIIIIIIIIIII 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 S Time (hours) — Inflow — Primary 2016-12-28 SWM Timberland Park 24-hr S1 10-yr Rainfall=5.58" Prepared by Microsoft Printed 1/9/2017 HydroCAD® 10.00-14 s/n 07714 ©2015 HydroCAD Software Solutions LLC Page 9 Summary for Pond A2-P: B10 2 Inflow Area = 2.320 ac, 0.00% Impervious, Inflow Depth = 3.12" for 10-yr event Inflow = 8.61 cfs @ 12.03 hrs, Volume= 0.602 of Outflow = 1.29 cfs @ 12.60 hrs, Volume= 0.421 af, Atten= 85%, Lag= 34.3 min Primary = 1.29 cfs @ 12.60 hrs, Volume= 0.421 of Routing by Stor-Ind method, Time Span= 1.00-40.00 hrs, dt= 0.01 hrs Peak Elev= 423.46' @ 12.60 hrs Surf.Area= 5,516 sf Storage= 12,743 cf Plug -Flow detention time= 267.9 min calculated for 0.421 of (70% of inflow) Center -of -Mass det. time= 155.9 min ( 994.9 - 839.0 ) Volume Invert Avail.Storage Storage Description #1 416.67' 15,880 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Voids Inc.Store Cum.Store (feet) (sq-ft) (%) (cubic -feet) (cubic -feet) 416.67 3,212 0.0 0 0 419.00 3,212 40.0 2,994 2,994 420.00 3,212 25.0 803 3,797 422.00 4,224 25.0 1,859 5,656 424.00 6,000 100.0 10,224 15,880 Device Routing Invert Outlet Devices #1 Primary 422.50' Custom Weir/Orifice, Cv= 2.62 (C= 3.28) Head (feet) 0.00 1.00 1.00 1.50 Width (feet) 0.42 0.42 16.00 16.00 Primary OutFlow Max=1.28 cfs @ 12.60 hrs HW=423.46' (Free Discharge) L1=Custom Weir/Orifice (Weir Controls 1.28 cfs @ 3.20 fps) 2016-12-28 SWM Timberland Park 24-hr S1 10-yr Rainfall=5.58" Prepared by Microsoft Printed 1/9/2017 HydroCADO 10.00-14 s/n 07714 © 2015 HydroCAD Software Solutions LLC Page 10 3 0 LL Pond A2-P: BIO 2 Hydrograph illllll I illlill�lll�llllllllll 8.61 cfs IIIIIIII n w I, ea=23 a I_ IIIIIIII -�ealk-�ioV'42� 1.�61111 IIIIIIII torte Iqe= 7 -Cfl IIIIIIII IIIIIIIIIIIIIIIITIIIIIIIIIII IIIIII IIIIIIIIIIIII TITITI 1.29cfsTITI T ITITITI T ITITITI T rtIT1�1 TTITI T ITITITI T TITITI T 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 Time (hours) — Inflow — Primary 2016-12-28 SWM Timberland Park 24-hr S1 100-yr Rainfall=9.16" Prepared by Microsoft Printed 1/9/2017 HvdroCAD® 10.00-14 s/n 07714 ©2015 HvdroCAD Software Solutions LLC Paae 11 Time span=1.00-40.00 hrs, dt=0.01 hrs, 3901 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method SubcatchmentA1-10YR: POST DA-Al Runoff Area=1.850 ac 0.00% Impervious Runoff Depth=5.85" Tc=5.0 min CN=73 Runoff=10.42 cfs 0.902 of SubcatchmentA2-10YR: POST DA-A2 Runoff Area=2.320 ac 0.00% Impervious Runoff Depth=6.35" Tc=5.0 min CN=77 Runoff=14.07 cfs 1.227 of SubcatchmentA3-S: POST DA-A3 Runoff Area=0.040 ac 0.00% Impervious Runoff Depth=4.35" Tc=5.0 min CN=61 Runoff=0.17 cfs 0.015 of Reach A-R: POST POA 1 (30" CMP) Inflow=20.63 cfs 1.828 of Outflow=20.63 cfs 1.828 of Pond Al-P: BIO 1 Peak Elev=435.72' Storage=11,352 cf Inflow=10.42 cfs 0.902 of Outflow=8.06 cfs 0.768 of Pond A2-P: BIO 2 Peak Elev=423.85' Storage=14,968 cf Inflow=14.07 cfs 1.227 of Outflow=12.56 cfs 1.046 of 2016-12-28 SWM Timberland Park 24-hr S1 100-yr Rainfall=9.16" Prepared by Microsoft Printed 1/9/2017 HydroCAD® 10.00-14 s/n 07714 ©2015 HydroCAD Software Solutions LLC Page 16 Summary for Pond Al-P: B10 1 Inflow Area = 1.850 ac, 0.00% Impervious, Inflow Depth = 5.85" for 100-yr event Inflow = 10.42 cfs @ 12.03 hrs, Volume= 0.902 of Outflow = 8.06 cfs @ 12.08 hrs, Volume= 0.768 af, Atten= 23%, Lag= 2.9 min Primary = 8.06 cfs @ 12.08 hrs, Volume= 0.768 of Routing by Stor-Ind method, Time Span= 1.00-40.00 hrs, dt= 0.01 hrs Peak Elev= 435.72' @ 12.08 hrs Surf.Area= 5,572 sf Storage= 11,352 cf Plug -Flow detention time= 182.3 min calculated for 0.768 of (85% of inflow) Center -of -Mass det. time= 108.8 min ( 940.4 - 831.6 ) Volume Invert Avail.Storage Storage Description #1 427.67' 12,974 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Voids Inc.Store Cum.Store (feet) (sq-ft) (%) (cubic -feet) (cubic -feet) 427.67 1,795 0.0 0 0 431.00 1,795 40.0 2,391 2,391 432.50 1,795 40.0 1,077 3,468 434.00 2,627 25.0 829 4,297 436.00 6,050 100.0 8,677 12,974 Device Routing Invert Outlet Devices #1 Primary 434.50' Custom Weir/Orifice, Cv= 2.62 (C= 3.28) Head (feet) 0.00 0.80 0.80 1.30 Width (feet) 0.25 0.25 8.00 8.00 Primary OutFlow Max=8.03 cfs @ 12.08 hrs HW=435.72' (Free Discharge) L1=Custom Weir/Orifice (Weir Controls 8.03 cfs @ 2.25 fps) 2016-12-28 SWM Timberland Park 24-hr S1 100-yr Rainfall=9.16" Prepared by Microsoft Printed 1/9/2017 HydroCAD® 10.00-14 s/n 07714 ©2015 HydroCAD Software Solutions LLC Page 18 Summary for Pond A2-P: B10 2 Inflow Area = 2.320 ac, 0.00% Impervious, Inflow Depth = 6.35" for 100-yr event Inflow = 14.07 cfs @ 12.03 hrs, Volume= 1.227 of Outflow = 12.56 cfs @ 12.06 hrs, Volume= 1.046 af, Atten= 11 %, Lag= 1.8 min Primary = 12.56 cfs @ 12.06 hrs, Volume= 1.046 of Routing by Stor-Ind method, Time Span= 1.00-40.00 hrs, dt= 0.01 hrs Peak Elev= 423.85' @ 12.06 hrs Surf.Area= 5,864 sf Storage= 14,968 cf Plug -Flow detention time= 173.0 min calculated for 1.046 of (85% of inflow) Center -of -Mass det. time= 99.5 min ( 919.9 - 820.4 ) Volume Invert Avail.Storage Storage Description #1 416.67' 15,880 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Voids Inc.Store Cum.Store (feet) (sq-ft) (%) (cubic -feet) (cubic -feet) 416.67 3,212 0.0 0 0 419.00 3,212 40.0 2,994 2,994 420.00 3,212 25.0 803 3,797 422.00 4,224 25.0 1,859 5,656 424.00 6,000 100.0 10,224 15,880 Device Routing Invert Outlet Devices #1 Primary 422.50' Custom Weir/Orifice, Cv= 2.62 (C= 3.28) Head (feet) 0.00 1.00 1.00 1.50 Width (feet) 0.42 0.42 16.00 16.00 Primary OutFlow Max=12.52 cfs @ 12.06 hrs HW=423.85' (Free Discharge) L1=Custom Weir/Orifice (Weir Controls 12.52 cfs @ 2.10 fps) Project: Timberland Park Apmts Drainage Area: DA-B Project #: 34160034 Date 12/29/2016 Drainage Area A: Total Disturbed Area: 1.25 acres 1 Year RVPre-Developed 0.06 of RVDeveloped 0.07 of Improvement Factor I.F. 0.80 QPre-Developed 0.21 cfs Enercgv Balance Equation: QDeveloped < I.F-*(QPre-Developed* RVPre-Developed/RVDeveloped Maximum QDeveloped to meet Energy Equation: I0.14 cfs • From HydroCAD • From HydroCAD Disturbed Area Exceeds 1 Acre From HydroCAD Equation from 9VAC25-870-66, Section B. 3. Actual QDeveloped I cfs ` From HydroCAD Meets Channel Protection Requirements B2-S POt DA-B2 POST DA-B1 � B-P DET PI� Subcat Reach on Link B3-S OST DA-63 POA2-S POST POA 2 2016-12-28 SWM Timberland Park 24-hr S1 1-yr Rainfall=3.05" Prepared by Microsoft Printed 1/10/2017 HydroCAD® 10.00-14 s/n 07714 ©2015 HydroCAD Software Solutions LLC Page 2 Time span=1.00-40.00 hrs, dt=0.01 hrs, 3901 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method SubcatchmentB1-S: POST DA-B1 Runoff Area=0.610 ac 39.34% Impervious Runoff Depth=0.84" Flow Length=719' Tc=11.3 min CN=72 Runoff=0.46 cfs 0.043 of SubcatchmentB2-S: POST DA-B2 Runoff Area=0.850 ac 27.06% Impervious Runoff Depth=0.79" Tc=5.0 min CN=71 Runoff=0.80 cfs 0.056 of SubcatchmentB3-S: POST DA-B3 Runoff Area=0.420 ac 0.00% Impervious Runoff Depth=0.38" Tc=5.0 min CN=61 Runoff=0.11 cfs 0.013 of Pond B-P: DET PIPE Peak Elev=410.36' Storage=550 cf Inf1ow=1.11 cfs 0.099 of Outflow=0.50 cfs 0.099 of Link POA2-S: POST POA 2 Inflow=0.56 cfs 0.112 of Primary=0.56 cfs 0.112 of 2016-12-28 SWM Timberland Park 24-hr S1 1-yr Rainfall=3.05" Prepared by Microsoft Printed 1/10/2017 HydroCAD®10.00-14 s/n 07714 ©2015 HydroCAD Software Solutions LLC Page 3 Summary for Subcatchment B1-S: POST DA-B1 Runoff = 0.46 cfs @ 12.12 hrs, Volume= 0.043 af, Depth= 0.84" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 1.00-40.00 hrs, dt= 0.01 hrs Timberland Park 24-hr S1 1-yr Rainfall=3.05" Area (ac) CN Description 0.370 55 Woods, Good, HSG B 0.240 98 Paved roads w/curbs & sewers, HSG B 0.610 72 Weighted Average 0.370 60.66% Pervious Area 0.240 39.34% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 4.8 35 0.0850 0.12 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.69" 2.1 154 0.0580 1.20 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 4.4 530 0.0100 2.03 Shallow Concentrated Flow, Paved Kv= 20.3 fas 11.3 719 Total Subcatchment B1-S: POST DA-B1 Hydrograph - - I - I — I — — - �I _Runoff 0.46 cfs I l 1 T I �I H "Ti"Waa1n""r 2�- ir�ll 1 H I H 1 HI H I I HI H IH I H I HI H IHRIa�nf a 3�05'r I-T I T I �I H I �I H 1� I 1 w H H I H H 1 H 1 HI H IH It H �dio*IDeoth�Ot O 028 0 0.2a 0.22 3 �n1 0.2 1HIt1 I� 1HI H 1 f I—tItI�I H I—tI+Itd�� 0.18 0.16 0.14 I� TI I �I I 14 TI H I� �I H 0.12 0.1 1� I t I tI H I t I t1 H I� I t I fit H 1� It I tl H I 0.08 00 0.04 I4I�I H IH I-� I H IH I-4I-�I�-I H I-4I-�I4-I H 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 Time (hours) 2016-12-28 SWM Timberland Park 24-hr S1 1-yr Rainfall=3.05" Prepared by Microsoft Printed 1/10/2017 HydroCAD®10.00-14 s/n 07714 ©2015 HydroCAD Software Solutions LLC Page 4 Summary for Subcatchment 132-S: POST DA-132 Runoff = 0.80 cfs @ 12.03 hrs, Volume= 0.056 af, Depth= 0.79" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 1.00-40.00 hrs, dt= 0.01 hrs Timberland Park 24-hr S1 1-yr Rainfall=3.05" Area (ac) CN Description 0.620 61 >75% Grass cover, Good, HSG B 0.230 98 Paved parking, HSG B 0.850 71 Weighted Average 0.620 72.94% Pervious Area 0.230 27.06% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Subcatchment 132-S: POST DA-132 Hydrograph 0.85 0.80 cfs — �i I� —Runoff 0$ I-T 7 I—f H 7 I�rb�ralnc �2lirl1i� 0.75 0.7 1- + 1 HI H -f 1 + 1 HI H IH I H I HI H Hkalnfa03k0i5'r 0 0.6 I��I �I �- � I�I �I �- I� %'o � V65 I � I0.55 w 0.5 I--LLH-L1LH—L-L unVolume- -LI k6"OfIDlelbth;�11D 7 - 3 0.45 7 T T H T 1� ��0� ° U.0.4 0.35 1- ItI tI H Itl H I-i I--- I t I fit H 1-1- 1 t I tl H I 0.3 0.25 1-+I+1-IH 1+1-1H1-41+14-1H1-41+14-IH 0.2 0.15 1�IJ-I�I�l ICI�I"H1�I�IHH1�14- H1 0.1 nnc II1111 111 11111 11 1I 11 11 1 12 13 14 15 16 17 18 19 20 21 22, Time (hours) 2016-12-28 SWM Timberland Park 24-hr S1 1-yr Rainfall=3.05" Prepared by Microsoft Printed 1/10/2017 HydroCAD®10.00-14 s/n 07714 ©2015 HydroCAD Software Solutions LLC Page 5 Summary for Subcatchment B3-S: POST DA-B3 Runoff = 0.11 cfs @ 12.05 hrs, Volume= 0.013 af, Depth= 0.38" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 1.00-40.00 hrs, dt= 0.01 hrs Timberland Park 24-hr S1 1-yr Rainfall=3.05" Area (ac) CN Description 0.420 61 >75% Grass cover, Good, HSG B 0.420 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Subcatchment B3-S: POST DA-B3 Hydrograph 0.115 0.11 0.11 cfs 1 1 —Runoff 0.105.1 00 09 1-1 H I::AaTnf a:W3M5' 0 0.08 0.08 H H 1 H 1 H IH H 1 ° H i� T 2 V-olume= 'I3 0.075 n a 0.65 H I+ 1 H H 1+ 1 -H H H I+ I f1 kii6-o flD�ekh�01:3i8' _20.06 055 11ITIDH 111UH11111UH111��7�=I- 0.045oLL0.05 1H I H 1 HI HI 1 H 1 HI HI IH 1 H 1 HI H IH 1 H I HI H 0.04 0.035 1- t I tI H I t I t1 H I-t I t I fit H I-t I t I tl H I 0.03 0 .025 0.02 0.02 H TI TI H I -TIT D E JIITI H 0.015 0.01 HIH HI H HI HIHIHI H I4 +I - H 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 3132 33 34 35 36 37 38 39 40 Time (hours) 2016-12-28 SWM Timberland Park 24-hr S1 1-yr Rainfall=3.05" Prepared by Microsoft Printed 1/10/2017 HydroCAD® 10.00-14 s/n 07714 ©2015 HydroCAD Software Solutions LLC Page 6 Summary for Pond B-P: DET PIPE Inflow Area = 1.460 ac, 32.19% Impervious, Inflow Depth = 0.81" for 1-yr event Inflow = 1.11 cfs @ 12.05 hrs, Volume= 0.099 of Outflow = 0.50 cfs @ 12.37 hrs, Volume= 0.099 af, Atten= 55%, Lag= 19.4 min Primary = 0.50 cfs @ 12.37 hrs, Volume= 0.099 of Routing by Stor-Ind method, Time Span= 1.00-40.00 hrs, dt= 0.01 hrs Peak Elev= 410.36' @ 12.37 hrs Surf.Area= 695 sf Storage= 550 cf Plug -Flow detention time= 6.1 min calculated for 0.098 of (100% of inflow) Center -of -Mass det. time= 6.1 min ( 900.8 - 894.7 ) Volume Invert Avail.Storage Storage Description #1 408.93' 1,131 cf 24.0" Round Pipe Storage x 2 L= 180.0' S= 0.0050 T Device Routing Invert Outlet Devices #1 Primary 408.83' 18.0" Round Culvert L= 127.2' RCP, sq.cut end projecting, Ke= 0.500 Inlet / Outlet Invert= 408.83' / 408.19' S= 0.0050 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf #2 Device 1 410.83' Custom Weir/Orifice, Cv= 2.62 (C= 3.28) Head (feet) 0.00 2.17 Width (feet) 3.00 3.00 #3 Device 1 408.83' 4.0" Vert. Orifice/Grate C= 0.600 #4 Device 1 410.33' Custom Weir/Orifice, Cv= 2.62 (C= 3.28) Head (feet) 0.00 0.50 Width (feet) 0.50 0.50 Primary OutFlow Max=0.50 cfs @ 12.37 hrs HW=410.36' (Free Discharge) L1=Culvert (Passes 0.50 cfs of 6.46 cfs potential flow) 2=Custom Weir/Orifice ( Controls 0.00 cfs) 3=Orifi ce/G rate (Orifice Controls 0.49 cfs @ 5.62 fps) 4=Custom Weir/Orifice (Weir Controls 0.01 cfs @ 0.54 fps) 2016-12-28 SWM Timberland Park 24-hr S1 1-yr Rainfall=3.05" Prepared by Microsoft Printed 1/10/2017 HydroCAD®10.00-14 s/n 07714 ©2015 HydroCAD Software Solutions LLC Page 7 Pond B-P: DET PIPE Hydrograph 3 0 LL 1.11 afs TI TI T I I I II WIM in, f io, w real I1I.60 ac TI TI T IT T�eak �ev=4l10.36�'I IIIIIII III I I Siol rlal lel-l5l56l cf IIIIIIIIIIIII I' 'I 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 Time (hours) — Inflow — Primary 2016-12-28 SWM Timberland Park 24-hr S1 1-yr Rainfall=3.05" Prepared by Microsoft Printed 1/10/2017 HydroCAD® 10.00-14 s/n 07714 ©2015 HydroCAD Software Solutions LLC Page 8 Summary for Link POA2-S: POST POA 2 Inflow Area = 1.880 ac, 25.00% Impervious, Inflow Depth = 0.71" for 1-yr event Inflow = 0.56 cfs @ 12.35 hrs, Volume= 0.112 of Primary = 0.56 cfs @ 12.35 hrs, Volume= 0.112 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 1.00-40.00 hrs, dt= 0.01 hrs Link POA2-S: POST POA 2 Hydrograph 0.6 0.56 cfs _ Inflow Primary 0.55 4+ I H H I H H H L I Area=1.880 4 0 5 17 TI -7I FT �I �I 17 of ow �I n I� �I ad I� -I 0.45 — — IIIIIIIIII IIIIIIIIIIIIIIIIIIIII- w 0.35 11 LI Il I L I LI Li I I L LJ -L I L I LI U I L J 0 0.3 414 HI HI 1-4I HI HI IH I H I HI H IH I H I HI H 14 LL 02 I I I IIIIIIIIIIIIIIIIIIIIII 0.15 0.1 1 I LI I- III LI IL III I 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 Time (hours) 2016-12-28 SWM Timberland Park 24-hr S1 10-yr Rainfall=5.58" Prepared by Microsoft Printed 1/10/2017 HydroCAD® 10.00-14 s/n 07714 ©2015 HydroCAD Software Solutions LLC Page 9 Time span=1.00-40.00 hrs, dt=0.01 hrs, 3901 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method SubcatchmentB1-S: POST DA-B1 Runoff Area=0.610 ac 39.34% Impervious Runoff Depth=2.65" Flow Length=719' Tc=11.3 min CN=72 Runoff=1.46 cfs 0.135 of SubcatchmentB2-S: POST DA-B2 Runoff Area=0.850 ac 27.06% Impervious Runoff Depth=2.56" Tc=5.0 min CN=71 Runoff=2.57 cfs 0.182 of SubcatchmentB3-S: POST DA-B3 Runoff Area=0.420 ac 0.00% Impervious Runoff Depth=1.73" Tc=5.0 min CN=61 Runoff=0.80 cfs 0.061 of Pond B-P: DET PIPE Peak Elev=411.18' Storage=1,035 cf Inflow=3.65 cfs 0.317 of Outflow=3.59 cfs 0.317 of Link POA2-S: POST POA 2 Inflow=4.34 cfs 0.377 of Primary=4.34 cfs 0.377 of 2016-12-28 SWM Timberland Park 24-hr S1 10-yr Rainfall=5.58" Prepared by Microsoft Printed 1/10/2017 HydroCAD®10.00-14 s/n 07714 ©2015 HydroCAD Software Solutions LLC Page 10 Summary for Subcatchment B1-S: POST DA-B1 Runoff = 1.46 cfs @ 12.11 hrs, Volume= 0.135 af, Depth= 2.65" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 1.00-40.00 hrs, dt= 0.01 hrs Timberland Park 24-hr S1 10-yr Rainfall=5.58" Area (ac) CN Description 0.370 55 Woods, Good, HSG B 0.240 98 Paved roads w/curbs & sewers, HSG B 0.610 72 Weighted Average 0.370 60.66% Pervious Area 0.240 39.34% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 4.8 35 0.0850 0.12 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.69" 2.1 154 0.0580 1.20 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 4.4 530 0.0100 2.03 Shallow Concentrated Flow, Paved Kv= 20.3 fas 11.3 719 Total N w 0 LL Subcatchment B1-S: POST DA-B1 Hydrograph III IIIIIIIII it IIII 1.46 cfs 41me�rl�nd (Park 241-Hr S� �O y� Rainfall�5.581' I I I I� R�npff Area o.s1 o ac uhh 4 Volumb-0 1 15l ai Runoff Pdpi h�2.651' " Ipvr en7t =719' 1 3 rri i� 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 41 Time (hours) — Runoff 2016-12-28 SWM Timberland Park 24-hr S1 10-yr Rainfall=5.58" Prepared by Microsoft Printed 1/10/2017 HydroCAD®10.00-14 s/n 07714 ©2015 HydroCAD Software Solutions LLC Page 11 Summary for Subcatchment B2-S: POST DA-B2 Runoff = 2.57 cfs @ 12.03 hrs, Volume= 0.182 af, Depth= 2.56" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 1.00-40.00 hrs, dt= 0.01 hrs Timberland Park 24-hr S1 10-yr Rainfall=5.58" Area (ac) CN Description 0.620 61 >75% Grass cover, Good, HSG B 0.230 98 Paved parking, HSG B 0.850 71 Weighted Average 0.620 72.94% Pervious Area 0.230 27.06% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, w 3 0 LL Subcatchment B2-S: POST DA-B2 Hydrograph �Zgnoff Pepth72.56" Tc=5.0 min III ��=17� I I I I I I I I I I I 77777— 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 1 S 19 20 21 25 29 32 22 23 24 26 27 28 30 31 33 34 35 36 37 38 39 41 Time (hours) — Runoff 2016-12-28 SWM Timberland Park 24-hr S1 10-yr Rainfall=5.58" Prepared by Microsoft Printed 1/10/2017 HydroCAD®10.00-14 s/n 07714 ©2015 HydroCAD Software Solutions LLC Page 12 Summary for Subcatchment B3-S: POST DA-B3 Runoff = 0.80 cfs @ 12.03 hrs, Volume= 0.061 af, Depth= 1.73" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 1.00-40.00 hrs, dt= 0.01 hrs Timberland Park 24-hr S1 10-yr Rainfall=5.58" Area (ac) CN Description 0.420 61 >75% Grass cover, Good, HSG B 0.420 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Subcatchment B3-S: POST DA-B3 Hydrograph o.s TIT T IT80Ti ds i i T 1� I.T IC�II TI I Tirl l"nWP �4-hri1 �y� 0.75 0.7 1T T I tI I-f -- I t I t1 I-j I--- I t I fit 1-I I--- f."�"81' 0.65 0.6 14 �-- I HI HI H 1 H 1 HI H IH 1 H 1 I FCu%nj 061' a ffoluZ Z 05 0. w 0.5 1 L L I_L I LI � I_L I_L I LI l�4"ff_Relpth�1L731' 3 0.45 IT T -I- T -I - I- T c.0 iin TI-I- —T � ° 0.4 U. 0.35 1� ItI tl rl ITI fit �-] 1-1 1t T iT I-1 1 t I t H 0.3 0.2 5 14 1 H H 1+ 1 H H 14 1 H 1 - HI H 14 I H I HI H I- 0.2 0.15 1 �I - -1 I I I �-1 I I I - I I I I J- 1-I I- 0.1 IIIIIIIIIII IIIIIIIIIIIIIIIIIIIIIIIII 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 3132 33 34 35 36 37 38 39 40 Time (hours) — Runoff 2016-12-28 SWM Timberland Park 24-hr S1 10-yr Rainfall=5.58" Prepared by Microsoft Printed 1/10/2017 HydroCAD® 10.00-14 s/n 07714 ©2015 HydroCAD Software Solutions LLC Page 13 Summary for Pond B-P: DET PIPE Inflow Area = 1.460 ac, 32.19% Impervious, Inflow Depth = 2.60" for 10-yr event Inflow = 3.65 cfs @ 12.04 hrs, Volume= 0.317 of Outflow = 3.59 cfs @ 12.05 hrs, Volume= 0.317 af, Atten= 2%, Lag= 0.8 min Primary = 3.59 cfs @ 12.05 hrs, Volume= 0.317 of Routing by Stor-Ind method, Time Span= 1.00-40.00 hrs, dt= 0.01 hrs Peak Elev= 411.18' @ 12.05 hrs Surf.Area= 355 sf Storage= 1,035 cf Plug -Flow detention time= 6.6 min calculated for 0.316 of (100% of inflow) Center -of -Mass det. time= 6.6 min ( 864.3 - 857.8 ) Volume Invert Avail.Storage Storage Description #1 408.93' 1,131 cf 24.0" Round Pipe Storage x 2 L= 180.0' S= 0.0050 T Device Routing Invert Outlet Devices #1 Primary 408.83' 18.0" Round Culvert L= 127.2' RCP, sq.cut end projecting, Ke= 0.500 Inlet / Outlet Invert= 408.83' / 408.19' S= 0.0050 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf #2 Device 1 410.83' Custom Weir/Orifice, Cv= 2.62 (C= 3.28) Head (feet) 0.00 2.17 Width (feet) 3.00 3.00 #3 Device 1 408.83' 4.0" Vert. Orifice/Grate C= 0.600 #4 Device 1 410.33' Custom Weir/Orifice, Cv= 2.62 (C= 3.28) Head (feet) 0.00 0.50 Width (feet) 0.50 0.50 Primary OutFlow Max=3.58 cfs @ 12.05 hrs HW=411.18' (Free Discharge) L1=Culvert (Passes 3.58 cfs of 8.84 cfs potential flow) 2=Custom Weir/Orifice (Weir Controls 2.01 cfs @ 1.93 fps) 3=Orifi ce/G rate (Orifice Controls 0.62 cfs @ 7.11 fps) 4=Custom Weir/Orifice (Orifice Controls 0.94 cfs @ 3.77 fps) 2016-12-28 SWM Timberland Park 24-hr S1 10-yr Rainfall=5.58" Prepared by Microsoft Printed 1/10/2017 HydroCAD®10.00-14 s/n 07714 ©2015 HydroCAD Software Solutions LLC Page 14 T- 3 0 LL Pond B-P: DET PIPE Hydrograph +I +-I h I—f I-� I +-I �-I in, f io, w real I11. 60 ac — -�� � � ��i �IIIIIIIIIIIIIII''�'�II torage=1,0 I35 cf IIIIIIIIIIIIIIIpIIIIIiII t I tI 11 I-� I t I t lfl It l t I t-I MAI 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 Time (hours) — Inflow — Primary 2016-12-28 SWM Timberland Park 24-hr S1 10-yr Rainfall=5.58" Prepared by Microsoft Printed 1/10/2017 HydroCAD® 10.00-14 s/n 07714 ©2015 HydroCAD Software Solutions LLC Page 15 Summary for Link POA2-S: POST POA 2 Inflow Area = 1.880 ac, 25.00% Impervious, Inflow Depth = 2.41" for 10-yr event Inflow = 4.34 cfs @ 12.05 hrs, Volume= 0.377 of Primary = 4.34 cfs @ 12.05 hrs, Volume= 0.377 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 1.00-40.00 hrs, dt= 0.01 hrs Link POA2-S: POST POA 2 Hydrograph t1MIIIWIIWIWIIWIWIIW1 IIIII I in1fid',l I,�e� ��80 IIII ITIT1TIT ITITITITITITI11 TIT TITIIT IIIIIIIIIIII IIIIIIIIIIIIIIIIIIIIIIIIII 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 41 Time (hours) — Inflow -111 — Primary N t\ \ M 100 0 100 200 300 — '01\\\ L SCALE: 1 99 - 100' /// �/ �/ - ?y ✓r // /� / / (,'(LAY"/! /�v / A" STIR STR �1' \ \ J I� 034 CS // / // /�\1 \\ 1 / \ // l / ��/__✓ Ff!� J_ ✓y�� r �` .0 IMP. \� 1 l\�� \` -/ '��✓�� i%�%� ��%-/��'�� ` �y�iT-i / / - ---1 y' STIR 18 STIR --, 1 \ 0.21 ACS H//\ --ice/�_ ✓%�=.ii%/�y�/i/����j �,ryi��l �/� / 0.27ACS P. / � \ \ � I � � �'� �_ _ � Eiji � %; �, •���i/- ''f �l _ � y � � l \ I I ,f STIR #4 F 0.0.3��82ACS I I STR/12 \ I ?I0.02 �I ACS E FLUME 1/4- _ \ \\� 0.65 ACS ACSJMP- \ STIR#30 ° STIR#26 / / / i 0.23 ACS D 0.11 ACS 0.08 ACS / / 0. 0 AC I P 36 \ \ .05 A3 IMP. 0.05 ACS IMP. 1 / / / / ✓ / 0.44 ACS \ \ j 7 / ( l l /' ✓r' r �� i / / I I \ \ \ ` °e \ � / / STIR {/10 1 / / / �/' �'��✓' /� ��' // I I I 11 1 1 \ \ �/ ° \\ / ✓' ' 0.31 ACS 38 / 19 ACS \ ! I I I I w .balzerxc stauaton New River Valley Roanoke Richmond Harrisonburg Balzer and Associates, Inc 128 West Market Street Suite 103 Harrisonburg, VA 22801 540-433-1908 Q Q Z U I.0 F > & (9 n d? z w Z' C) Q 0 Zo H w Q° W o 2 LU Z co m a DRAWN BY DKO DESIGNED BY DKO CHECKED BY WSM DATE 09-07-2016 SCALE 1"=100' REVISIONS: 09-26-2016 ARB 12-09-2016 ISP #1 01-04-2017 WPo #1 SHEET NO. DA-3 JOB NO. 34160034 CURB INLET WORKSHEET - SAG INLETS PROJECT NAME: Timberland Park Apartments PROJECT #: DATE: 11 /27/2016 BY: DKO 34160034 Sag Inlet SUM CA = 0.20 INLET SLOPE LONGITUDINAL L PIEuo/NTL LENGTH SPREAD 0.0077 SAG SPREAD INLET # co INLET FROM INLET # L DA C TOTAL CO (IN) = 0.0 cfs 2 2.5' 4.34' 7.09' 1 2 3 4 0.19 0.08 0.9 0.35 Left Gutter Flow + CO = .796 cfs Check Storm Total Co (IN) _ Total Gutter Flow+CO(IN) = .0 cfs 1.294 cfs NOSE: B co (IN) FROM INLET Right Gutter Flow + CO = .0 cfs d = 0.20 R DA C 1 2 Total Gutter Flow = 796 cfs 3 d = 0.15 4 TOTAL STORM DESIGN DA ADJ. C DA C DA C DA C DA C VALUES 0.27 1 0.74 SLOT: N 1 2 3 4 Tc OLF C Length Sloe Tc CHAN. Length OH Tc INLET Tc 5.0 min FLOW 0.00 0.00 Sag Inlet SUM CA = 0.30 INLET SLOPE SLOPE (FT/FT) LENGTH SPREAD 0.01 SAG SPREAD INLET # co INLET FRO#INLET L DA C TOTAL CO (IN) = 0.0 cfs 4 6 528 690 6 1 2 3 4 0.33 0.01 0.9 0.35 Check Storm Total Co (IN) = Total Gutter Flow+CO(IN) = .040 cfs 1.993 cfs .0 .. Left Gutter Flow + CO = 1.202 cfs NOSE: B co (IN) FROM INLET # Right Gutter Flow + CO = .0 cfs d = 0.20 R DA C 1 2 Total Gutter Flow = 1.202 cfs 3 d = 0.14 4 TOTAL STORM DESIGNq0.820.77 DA C DA C DA C DA C VALUES SLOT: N 1 0.3 0.9 2 0.18 0.4 3 4 Tc OLF C Length Sloe Tc I CHAN. Length OH Tc INLET Tc 5.0 min FLOW I 1 0.00 0.001 bag Inlet SUM CA = 0.21 INLET SLOPE LONGITUDINAL SLOPE ] LENGTH SPREAD o.0.oz7373 2 5' 2.54' SAG SPREAD 7.42' INLET # CO (IN) FROM INLET # DA c TOTAL CO (IN) 0.0 cfs 10 1 1 2 3 4 0.19 0.12 0.9 0.35 Check Storm Total Co (IN) _ Total Gutter Flow+CO(IN) = .0 cfs 1.385 cfs Left Gutter Flow + CO = cfs NOSE: B co (IN) FROM INLET # Right Gutter Flow + CO = .852 .0 cfs d = 0.21 R DA C 1 2 Total Gutter Flow = .852 cfs 3 d = 0.15 4 TOTAL STORM DESIGN DA ADJ. C DA C DA C DA C DA C VALUES 0.31 1 0.69 SLOT: N 1 2 1 1 1 3 4 Tc OLF C Length Sloe Tc CHAN. Len th OH Tc INLET Tc 5.0 min FLOW 0.00 0.00 CURB INLET WORKSHEET - GRADE INLETS PROJECT NAME: Timberland Park Apartments PROJECT #: 34160034 DATE: 11 /27/2016 BY: DKO Grade Inlet "LET �LON&-rmNAL LENGTH Eff = Len. Req = 6.0' 1.00 5.86 SLOPE EAD 1.90' Gutter Flow = Carry Over (Il`= Total Flow = CARRY OVER OUT 0.00 .554 cfs .0 cfs 554 cfs SUM CA = 0.139 TOTAL CO (IN) = 0.000FROM INLET # CO (I") INLETDA C 6 1 2 3 4 0.15 0.01 0.9 0.35 Check Storm Total Co (IN) _ .0 cfs Total Gutter Flow+CO(IN) = .90 cfs Carry Over (Out) = 0.04 cfs NOSE: B SLOT: N 1 .- 005 C 0.9 DA C 2 0.02 0.4 3 DA C DA C 4 TOTAL STORM DESIGN DA ADJ. C VALUES 0.29 0.83 Tc OLF C Length Slope Tc 0.00 CHAN. Length AH TO INLET TO 5.0 min FLOW I I 0.00 raene "LET oNGlTuowAL LENGTH SLOPEUDINA 0.01 SLOPE SPREAD CARRY OVER OUT SUM CA TOTAL CO (IN) = 0.586 = 0.000 INLET # co ON) FROM INLET DA C 14 10.0' 7.70 0.01 18 1 2 3 4 0 34 0.8 0.9 0.35 Check Storm Total Co (IN) = .050 cfs Total Gutter Flow+CO(IN) = 3.859 cfs Carry Over (Out) = 0.28 cfs Gutter Flow = 2.344 cfs Eff = 1.00 Carry Over (Il`= .0 cfs 1 Len. Reg = 10.27 Total Flow = 2.344 cfs NOSE: B TOTAL STORM DESIGN DA ADJ. C VALUES 1.14 0.51 DA C DA C DA C DA C SLOT: N 1 2 3 4 Tc OLF C Length Slope Tc CHAN. Length AH Tc INLET To 5.0 min FLOW 0.00 0.00 tirade Inlet INLET LONGITUDINAL LENGTH SLOPEL= Eff = Len. Reg = 6.0' 0.99 6.35 SLOPE SPREAD 1.63' Gutter Flow = Carry Over (Il`= Total Flow = CARRY OVER OUT 0.00 .470 cfs .0 cfs .470 cfs SUM CA = 0.118 = TOTAL CO (IN) 0.000 INLET# co ON) ROM INLET # DA C0.0352 1 8 1 2 3 4 0 08 0.13 0.9 0.35 Check Storm Total Co (IN) _ .0 cfs Total Gutter Flow+CO(IN) = .764 cfs Carry Over (Out) = 0.05 cfs NOSE: B SLOT: N 1 DA C DA C 2 3 DA C DA C 4 TOTAL STORM DESIGN DA ADJ. C VALUES 0.21 0.56 Tc OLF C Length Slope Tc 0.00 CHAN. Length AH Tc INLET Tc 5.0 min FLOW 0.00 Grade Inlet '"ET g NNGI FrNTL LENGTH 0.0521 Eff = Len. Reg = 4.0' 0.88 5.73 SLOPE SPREAD 1.24' Gutter Flow Carry Over (Il`= Total Flow CARRY OVER (OUT) 0.03 = .278 cfs .0 cfs = .278 cfs SUM CA = 0.070 TOTAL CO (IN) = 0.000 INLET # co (IN) FROM INLET # DA C 20 1 2 3 4 0 05 0.07 O.g 0.35 Check Storm Total Co (IN) _ .0 cfs Total Gutter Flow+CO(IN) = .452 cfs Carry Over (Out) = 0.10 cfs NOSE: B SLOT: N 1 DA C DA C 2 3 DA C DA C 4 TOTAL STORM DESIGN DA I ADJ. C VALUES 0.12 0.58 Tc OLF C Length Sloe Tc 00 0. CHAN. Length AH Tc INLET TO 5.0 min FLOW 0.00 OTHER INLET WORKSHEET PROJECT NAME: Timberland Park Apartments PROJECT #: 34160034 DATE: 11 /27/2016 BY: DKO inlet DATA CALCULATIONS IDF CURVE REFERENCE: ALBEMARLE CO. OLF-Seelye from VDOT Drainage manual App 6D-1 Total Adj AREA C Time of Concentration Area= C ac= ###### %@ #DIV/O! ftOLF@ % 0.00 min 0.00 SLOT: N ac = ##k### %@ _C= C = #DIV/0! ft CF 4H = 0.00 min MH-1 ac = ###### %@ C = #DIV/0! ftCFAH = 0.00 min r ac = ###### %@ C = #DIV/O! Tc = 5.00 min ac = ###### %@ C = #DIV/0! ADJ. C' = 0.000 IC factor for OLF= Total Adj AREA C Time of Concentration Area = C 0.01 ac = 50 %@ 0.90 C = 0.45 ft OLF@ % = 0.00 min 12 0.02 ac 0.63 SLOT: N 0.01 ac = 50 %@ 0.35 C = 0.18 ft CF AH = 0.00 min Twe_ NYLOPLAST ac = 0 %@ _ C = 0.00 ft CF AH = 0.00 min Comments: 12" INLINE DRAIN WITH ac = 0 %@ C = 0.00 Tc = 5.00 min DOME GRATE ac = 0 %@ _ C = 0.00 ADJ. C' = 0.625 C factor for OLF= OTHER INLET WORKSHEET PROJECT NAME: Timberland Park Apartments PROJECT #: 34160034 IDF CURVE REFERENCE: ALBEMARLE CO. DATE: 11 /27/2016 BY: DKO OLF-Seelye from VDOT Drainage manual App 6D-1 inlet DATA CALCULATIONS Total Adj AREA C Time of Concentration Area = C 0.05 ac = 45.455 %@ 0.90 C = 0.41 ft OLF@ % = 0.00 min 3 O 0.11 ac 0.60 SLOT: N 0.06 ac = 54.545 %@ 0.35 C = 0.19 ft CF AH = 0.00 min Twe_ NYLOPLAST ac = 0 %@ _ C = 0.00 ft CF AH = 0.00 min Comments: 12" DRAIN BASIN WITH ac = 0 %@ C = 0.00 Tc = 5.00 min DOME GRATE ac = 0 %@ C = 0.00 ADJ. C' = 0.600 C factor for OLF= Total Adj AREA C Time of Concentration Area = C 0.05 ac = 62.5 %@ 0.90 C = 0.56 ft OLF@ % = 0.00 min 2 0.08 ac 0.69 SLOT: N 0.03 ac = 37.5 %@ 0.35 C = 0.13 ft CF AH = 0.00 min Twe_ NYLOPLAST ac = 0 %@ C = 0.00 ft CF 4H = 0.00 min Comments: 12" INLINE DRAIN WITH ac = 0 %@ _ C = 0.00 Tc = 13.52 min DOME GRATE ac = 0 %@ _ C = 0.00 ADJ. C' = 0.694 C factor for OLF= 7-1 Total Adj AREA C Time of Concentration Area = C 0.11 ac = 34.375 %@ 0.90 C = 0.31 ft OLF@ % = 0.00 min 38 0.32 ac 0.54 SLOT: N 0.21 ac = 65.625 %@ 0.35 C = 0.23 ft CF 4H = 0.00 min Type- NYLOPLAST ac = 0 %@ _ C = 0.00 ft CF AH = 0.00 min Comments: 12" INLINE DRAIN WITH ac = 0 %@ C = 0.00 Tc = 13.52 min STANDARD GRATE ac = 0 %@ _ C = 0.00 ADJ. C' = 0.539 IC factor for OLF= Total Adj AREA C Time of Concentration Area = C 0.11 ac = 25 %@ 0.90 C = 0.23 ft OLF@ % = 0.00 min 3 0.44 ac 0.49 SLOT: N 0.33 ac = 75 %@ 0.35 C = 0.26 ft CF AH = 0.00 min Twe_ NYLOPLAST ac = 0 %@ _ C = 0.00 ft CF AH = 0.00 min Comments: 12" INLINE DRAIN WITH ac = 0 %@ C = 0.00 Tc = 5.00 min STANDARD GRATE ac = 0 %@ _ C = 0.00 ADJ. C' = 0.488 IC factor for OLF= Total Adj AREA C Time of Concentration Area = C ac = ###### %@ = #DIV/0! ft OLF@ %= 0.00 min 1 6 0.00 ac 0.00 SLOT: N ac = ###### %@ _C _ C = #DIV/O! ft CF AH = 0.00 min Twe_ MH-1 ac = ###### %@ C = #DIV/0! ft CF AH = 0.00 min Comments: ac = ###### %@ C = #DIV/O! Tc = 5.00 min ac = ###### %@ C = #DIV/0! ADJ. C' = 0.000 IC factor for OLF= Total Adj AREA C Time of Concentration Area= C ac= ###### %@ #DIV/O! ft OLF@ % = 0.00 min 22 0.00 ac 0.00 SLOT: N ac = ###### %@ _C= _C = #DIV/0! ft CF AH = 0.00 min Twe_ NYLOPLAST ac = ###### %@ C = #DIV/O! ft CF AH = 0.00 min Comments: 12" INLINE DRAIN WITH ac = ###### %@ _ C = #DIV/0! Tc = 5.00 min SOLID TOP ac = ###### %@ C = #DIV/0! ADJ. C' = 0.000 C factor for OLF= 7-1 Total Adj AREA C Time of Concentration Area = C ac = ###### %@ = #DIV/0! ft OLF@ %= 0.00 min 24 0.00 ac 0.00 SLOT: N ac = ###### %@ _C _C = #DIV/O! ft CF AH = 0.00 min Twe- NYLOPLAST ac = ###### %@ C = #DIV/0! ft CF AH = 0.00 min Comments: 12"DRAINBASINWITH ac= ###### %@ _ C= #DIV/O! Tc = 5.00 min SOLID TOP ac = ###### %@ C = #DIV/0! ADJ. C' = 0.000 IC factor for OLF= Total Adj AREA C Time of Concentration Area C ac= ###### %@ #DIV/O! ft OLF@ %= 0.00 min 2 0.00 ac 0.00 SLOT: N ac = ###### %@ _C= _ C = #DIV/0! ft CF AH = 0.00 min Twe_ NYLOPLAST ac = ###### %@ C = #DIV/O! ft CF AH = 0.00 min Comments: 12" INLINE DRAIN WITH ac = ###### %@ _ C = #DIV/0! Tc = 5.00 min DOME GRATE ac = ###### %@ C = #DIV/0! ADJ. C' = 0.000 IC factor for OLF= OTHER INLET WORKSHEET I PROJECT NAME: Timberland Park Apartments PROJECT #: 34160034 DATE: 11 /27/2016 BY: DKO inlet DATA CALCULATIONS IDF CURVE REFERENCE: ALBEMARLE CO. OLF-Seelye from VDOT Drainage manual App 6D-1 Total Adj AREA C Time of Concentration Area = C ac = ###### %@ = #DIV/0! ft OLF@ %= 0.00 min 32 0.00 ac 0.00 SLOT: N ac = ###### %@ _C _C = #DIV/O! ft CF AH = 0.00 min NYLOPLAST ac = ###### %@ _ C = #DIV/0! ft CF AH = 0.00 min 12"DRAIN BASIN WITH ac= ###### %@ C= #DIV/O! Tc= 5.00 min SOLID TOP ac = ###### %@ C = #DIV/0! ADJ. C' = 0.000 C factor for OLF= Adj AREA C Time of Concentration Area C kCmments: ac= ###### %@ #DIV/O! ftOLF@ %= 0.00 min 34 0.00 SLOT: N ac = ###### %@ _C= _C = #DIV/0! ft CF AH = 0.00 min NYLOPLAST ac = ###### %@ C = #DIV/O! ft CF AH = 0.00 min 12" DRAIN BASIN WITH ac = ###### %@ C = #DIV/0! Tc = 5.00 min SOLID TOP ac = ###### %@ C = #DIV/O! ADJ. C' = 0.000 IC factor for OLF= I HYDROLOGY WORKSHEET PROJECT NAME: Timberland Park Apartments PROJECT #: 34160034 DATE: 11 /27/2016 BY: DKO OLF-Seelye from VDOT Drainage manual App 6D-1 inlet DATA CALCULATIONS FLUME Area = 0.65 ac C' Value Time of Concentration CA = 0.52 0.54 ac = 83.1 %@ 0.90 C = 0.75 ft OLF@ % = 0.00 min Tc = 5.00 0.11 ac = 16.9 %@ 0.35 C = 0.06 ft CF AH = 0.00 min I2 = 5.18 in/hr Q2 = 2.72 cfs ac = 0 %@ C = 0.00 ft CF AH = 0.00 min I10 = 6.67 in/hr Q10 = 3.50 cfs ac = 0 %@ C = 0.00 Tc = 5.00 min I25 = 7.48 in/hr Q25 = 4.31 cfs ac = 0 %@ C = 0.00 User defined I100 = 8.76 in/hr Q 100 = 5.74 cfs ADJ. C' = 0.807 C factor for OLF= STORM SEWER DESIGN RA l 7FR l Project: Timberland Park Apartments 10 YEAR FREQUENCY J� !Lil_l� Job# : 34160034 Date: 11/27/2016 OF CURVE REFERENCE: ALBEMARLE CO. By: DKO FROM TO DA CA TC RAINFALL RUN-OFF INVERT INVERT LENGTH DIAM. MANNING'S CAPACITY VELOCITY FLOW TIME PERCENT POINT POINT (ACRES) C INCR. ACCUM. (MINUTES) (IN/HR) (CFS) LINE UPPER LOWER (FEET) SLOPE (INCHES) N COEFF. (CFS) (F.P.S.) (MINUTES) CAPACITY 12 10 0.02 0.63 0.01 0.01 5.00 6.67 0.08 11 430.75 430.41 9.50 3.58% 12 0.011 7.96 3.25 0.05 0.01 10 8 0.31 0.69 0.21 0.23 5.05 6.65 1.50 9 430.31 430.01 59.14 0.51 % 15 0.011 5.44 3.80 0.26 0.28 8 6 0.00 0.00 0.00 0.23 5.31 6.56 1.48 7 429.91 429.41 82.89 0.60% 15 0.011 5.93 4.02 0.34 0.25 6 4 0.23 0.83 0.19 0.42 5.65 6.45 2.69 5 429.31 425.16 186.25 2.23 % 15 0.011 11.39 7.59 0.41 0.24 4 2 0.82 0.77 0.63 1.05 6.06 6.33 6.64 3 425.06 424.55 82.28 0.62% 18 0.011 9.77 5.88 0.23 0.68 2 1 0.27 0.74 0.20 1.25 6.29 6.26 7.82 1 424.45 422.00 197.29 1.24 % 18 0.011 13.83 8.05 0.41 0.57 20 18 1 0.12 0.58 0.07 0.07 1 5.00 6.67 0.46 19 1 413.29 1 412.39 11 42.11 1 2.14 % 15 11 0.011 1 11.16 4.41 1 0.16 0.04 18 16 0.21 0.56 0.12 0.19 5.16 6.61 1.24 17 409.89 409.00 178.15 0.50% 24 0.011 18.89 3.34 0.89 0.07 16 14 0.00 0.00 0.00 0.19 6.05 6.33 1.18 15 409.00 408.93 13.49 0.52 % 18 0.011 8.94 3.48 0.06 0.13 14 130UT 1.14 0.51 0.59 0.77 6.11 6.32 4.88 13 408.83 408.19 127.24 0.50% 18 0.011 8.80 5.11 0.42 0.55 36 34 0.44 0.49 0.21 0.21 5.00 6.67 1.43 35 443.08 442.82 17.41 1.49% 12 0.011 5.14 5.62 0.05 0.28 34 32 0.00 0.00 1 0.00 0.21 5.05 6.65 1 1.43 33 442.82 441.69 101.78 1.11 % 12 0.011 4.44 5.07 0.33 1 0.32 32 30 0.00 0.00 0.00 0.21 5.39 6.54 1.40 31 441.69 440.33 125.91 1.08% 12 0.011 4.37 4.99 0.42 0.32 30 28 1 0.11 0.60 0.07 0.28 1 5.81 6.41 1.80 29 1 440.33 1 438.33 11 32.48 1 6.16 % 12 11 0.011 11 10.44 9.89 0.05 0.17 28 26 0.00 0.00 0.00 0.28 5.86 6.39 1.79 27 438.33 436.40 67.60 2.86% 12 0.011 7.11 7.55 0.15 0.25 26 24 0.08 0.69 0.06 1 0.34 6.01 6.35 2.13 25 436.40 435.76 20.62 3.10 % 12 0.011 7.42 8.19 0.04 0.29 24 22 0.00 0.00 0.00 0.51 6.05 6.33 3.22 23 435.76 435.15 50.75 1.20% 12 0.011 4.61 6.28 0.13 0.70 22 21OUT 0.00 0.00 0.00 0.51 6.19 6.29 3.20 21 435.15 434.00 38.78 2.97% 12 0.011 7.25 9.11 0.07 0.44 38 24 0.32 0.54 0.17 0.17 13.52 4.76 0.82 37 437.50 435.76 67.71 2.57 % 12 0.011 6.75 1 5.76 0.20 0.12 1992 3.18 _U n- 0/3 -MME M gai gm 5= a now MW lam MIC'm own --- - ------ MM MI. -aim ------------ ----------- I ---------- Source: USDA-SCS III -164 Plate 3.18-3 1992 3.18 7-- =) CU M: It oy�Lo: fa + 0 c) v s- 4j Cli o O 41 41 Gj 11) — 4) E 41 nro n- m Source: USDA-SCS M= 1 % IMME ELM IN a'e I—m- - M� 1 Sam .11.1 M MEM11k; III -164 CD CD -1 (D Cli Ln Plate 3.18-3 rA 1992 3.18 _Z 3 O J LL- �-4 w CL CmH z a o in 0 V LL_ O o H H U H Ld M O O W U CL_ 1- Lu I- 3 O J O Q LL.. F- O CJ � H H Ln 7 LLJ H O � • • -� -sa$��� � � ���' moo'/ a�3�_3�_ - 'i`��? • s �� • M-.JCL Lim " Z • -_= - "•ii'CS� 1IL ,' Source: USDA-SCS O O O N .- q m Ram Maim w EAM Ems w N • Plate 3.18-3 III - 164 WATER QUALITY CALCULATIONS DEq Virginia Runoff Reduction Method New Development Compliance Spreadsheet -Version 3.0 C 2011 BMP Standards and Specifications 102013 Draft BMP Standards and Specifications Project Name: Timberland Park Apartments Date: 12/29/2016 BMP Design Specifications List: 2013 Draft Stds & Specs Site Information Post -Development Project (Treatment Volume and Loads) Land Cover (acres) ASoils BSoils CSoils DSoils Totals Forest/Open Space (acres) - undl sturbed, protected forest/c pen space or reforested land 0.00 Managed Turf (acres) - disturbed, graded for 3.09 yards or other turf to be mowed/managed 3.09 Impervious Cover (acres) 2.39 2.39 5.48 Constants Annual Rainfall (inches) 43 Target Rainfall Event (inches) 1.00 Total Phosphorus (TP) EMC(mg/L) 0.26 Total Nitrogen (TN) EMC(mg/L) 1.86 Target TP Load (lb/acre/yr) 0.41 Pj(unidess correction factor) 0.90 Rrmnff rnnfR,innfc fRvl ASoils BSoils CSoils DSoils 0.02 0.03 0.04 0.05 M 0.15 0.20 0.22 0.25 0.95 0.95 1 0.95 0.95 LAND 7P Load Reduction COVER SUMMARY Required (lb/yr) 4.34 POSTDEVELOPMENT Land Cover Summary 0.00 0.00 0% 3.09 0.20 56% 2.39 0.95 44% 5.48 0.53 Treatment Volume and Ni Treatment Volume (acre-k) Treatment Volume (cubic feet) TP Load (lb/yr) TN Wad(lb/yr) Informat'onal Pu oses Onl Forest/Open Space Cover (acres) Weighted Rv(forest) % Forest Managed Turf Cover (acres) Weighted Rv(turf) %Managed Turf Impervious Cover (acres) Rv(impervious) %Impervious Site Area (acres) Site Rv 0.2407 10,485 6.59 47.13 data input cells constant values wlculatian cells Virginia Runoff Reduction Method Worksheet DEQ Virginia Runoff Reduction Method New Development Compliance Spreadsheet - Version 3.0 BMP Design Specifications List: 2013 Draft Stds & Specs Site Summary Total Rainfall = 43 inches Site Land Cover Summary A soils B Soils C Soils D Soils Totals % of Total Forest/Open (acres) 0.00 0.00 0.00 0.00 0.00 0 Managed Turf (acres) 0.00 3.09 0.00 0.00 3.09 56 Impervious Cover (acres) 0.00 2.39 0.00 0.00 2.39 44 5.48 100 Site Tv and Land Cover Nutrient Loads Site Rv 0.53 Treatment Volume (ft) 10,485 TP Load (lb/yr) 6.59 TN Load (lb/yr) 47.13 Total TP Load Reduction Required (lb/yr) 4.34 Site Compliance Summary Total Runoff Volume Reduction (ft) 7,126 Total TP Load Reduction Achieved (lb/yr) 5.03 Total TN Load Reduction Achieved (lb/yr) 36.79 Remaining Post Development TP Load 1.56 (lb/yr) Remaining TP Load Reduction (lb/yr) Required 0.00 ** TARGET TP REDUCTION EXCEEDED BY 0.69 LB/YEAR ** --- --------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Drainage Area Summary Forest/Open (acres) D.A. A D.A. B D.A. C D.A. D D.A. E Total 0.00 0.00 0.00 0.00 0.00 0.00 Managed Turf (acres) 0.99 1.02 0.00 0.00 0.00 2.01 Impervious Cover (acres) 0.86 1.30 0.00 0.00 0.00 2.16 Total Area (acres) 1.85 2.32 0.00 0.00 0.00 4.17 Drainage Area Compliance Summary D.A. C D.A. D D.A. E Total __] TP Load Reduced (lb/yr) 2.08 2.95 0.00 0.00 0.00 5.03 Summary Print Virginia Runoff Reduction Method Worksheet TN Load Reduced (lb/yr) 15.22 21.58 0.00 10.00 10.00 36.79 Drainage Area A Summary Land Cover Summary Forest/Open (acres) A Soils B Soils C Soils D Soils Total % of Total 0.00 0.00 0.00 0.00 0.00 0 Managed Turf (acres) 0.00 0.99 0.00 0.00 0.99 54 Impervious Cover (acres) 0.00 0.86 0.00 0.00 0.86 46 1 1.85 1 BMP Selections Managed Turf Impervious BMP Treatment TP Load from Untreated TP Load TP Removed TP Remaining Downstream Practice Credit Area Cover Credit I a Volume (ft) Upstream to Practice (Ibs) (lb/yr) (lb/yr) Treatment to be (acres) Area (acres) Practices (Ibs) Employed Total Impervious Cover Treated (acres) 0.86 Total Turf Area Treated (acres) 0.99 Total TP Load Reduction Achieved in D.A. (lb/yr) 2.08 Total TN Load Reduction Achieved in D.A. (lb/yr) 15.22 Drainage Area B Summary Land Cover Summary A Soils B Soils C Soils D Soils Total % of Total Forest/Open (acres) 0.00 0.00 0.00 0.00 0.00 0 Managed Turf (acres) 0.00 1.02 0.00 0.00 1.02 44 Impervious Cover (acres) 0.00 1.30 0.00 0.00 1.30 56 1 2.32 1 BMP Selections Managed Turf Impervious BMP Treatment TP Load from Untreated TP Load TP Removed TP Remaining Downstream Practice Credit Area Cover Credit I s Volume (ft) Upstream to Practice (Ibs) (Ib/yr) (Ib/yr) Treatment to be (acres) Area (acres) Practices (Ibs) Employed Total Impervious Cover Treated (acres) 1.30 Total Turf Area Treated (acres) 1.02 Total TP Load Reduction Achieved in D.A. (lb/yr) 2.95 Total TN Load Reduction Achieved in D.A. (lb/yr) 21.58 Summary Print 1-yearstorm 2-yearstorm 10-yearstorm 3.05 3.69 5.58 Use NOAA Atios 14 (http://hdscnws.noaa.go lhdsc/pfds/) *Notes (see below): [11 The curve numbers and runoff volumes computed in this spreadsheet far each drainage area are limited in their applicability for determining and demonstrating compliance with water quantity requirements. See VRRM User's Guide and Documentation for additional information. [2) Runoff Volume (RV) for pre- and post -development drainage areas must be in volumetric units (e.g., acre-feet or cubic feet) when using the Energy Balance Equation. Runoff measured in watershed - inches and shown in the spreadsheet as RV(watershed-inch) can only be used in the Energy Balance Equation when the pre- and post -development drainage areas are equal. Otherwise RV(watershed-inch) must be multiplied by the drainage area. [3] Adjusted CNs are based on runoff reduction volumes as calculated in D.A. tabs. An alternative CN adjustment calculation for Vegetated Roofs is included in BMP specification No. 5. Drainage Area Curve Numbers and Runoff Depths* Curve numbers (CN, CNadj) and runoff depths (RV Developed) are computed with and without reduction practices. Drainage Area A A Solis B Soils C Soils D Soils Total Area (acres): 1.85 space or reforested land Forest/Open Space -- undisturbed, protected forest/openffi(acres) 30 0.00 55 0.00 70 0.00 77 Runoff Reduction Volume (ft3): 2,948 Managed Turf -- disturbed, graded for yards or otherturf to be mowed/managed 0.00 39 0.99 61 0.00 74 0.00 80 Impervious Caver 0.00 98 0.86 98 0.00 98 0.00 98 CN(D.A. A) 78 1-yearstorm 2-year storm 30-yearstorm RVce-loped (watershed -inch) with no Runoff Reduction* 1.16 1.64 3.z1 RVDevaloped (watershed -inch) with Runoff Reduction* 0.73 1.20 z.77 Adjusted CN* 70 n 73 *See Notes above Drainage Area B A Soils B Soils C Soils D Soils Total Area (acres): 2.32 Forest/Open Space -- undisturbed, protected forest/open space or reforested land Area (acres) CN 0.00 30 0.00 55 0.00 70 0.00 77 Runoff Reduction Volume (ft): 4 179 Managed Turf --disturbed, graded for yards or other turf to be mowed/managed Area (acres) CN 0.00 39 1.02 61 0.00 74 0.00 80 Impervious Cover Area (acres) CN 0.00 1.30 0.00 0.00 98 98 98 98 CN(D.A. a) 82 1-yearstorm 2-year storm 30-yearstorm 1.42 1.94 3.60 0.92 1.44 3.11 74 75 77 RVII.-loped (watershed -inch) with no Runoff Reduction* RVDe„eloped (watershed -inch) with Runoff Reduction* Adjusted CN* *See Notes above bALZEQ ,ar�s SPECIFICATION #9 - BIORETENTION BASIN A WORKSHEET Design Level Level #2 BMP Sizing Data Transcribed Runoff Reduction Worksheet PROJECT NAME: PROJECT #: DATE: BY: Treatment Volume (Tv) Level #2 Impervious 3,684 (cf) Level #2 Turf (cf) Timberland Park Apartments 34160034 1/10/2017 DKO Treatment Level Treatment Volume Total Coefficient (Tv) TvBMP 1.25 * 3,684 (cf) = 4,606 (cf) Equivalent Storage Depth Surface Storage 0.50 (ft) Bioretention Soil Media & Mulch 3.00 (ft) Choker Stone 0.33 (ft) Additional Gravel 2.00 (ft) Required Gravel Below Underdrain 1.00 (ft) Total Depth 6.83 (ft) Required Surface Area Treatment Volume Equivalent Storage Depth Pond Desien Elevations (ft Top of Bioretention Berm Top of Storage, High Flow Weir, Top of Riser P.T. Cell Low Flow Weir Top of Media Bottom of Media / Geotextile Fabric Bottom of Choker Stone Underdrain Invert Bottom of Gravel Flow Path Pre -Treatment Measures Length of shortest flow path w/ >20% contributing DA Overall length Ratio Measure 1 Measure 2 Pre -Treatment Cell Design Design Cell Surface Area Design Cell Depth Provided Storage Required Storage (TvBMP*0.15) 4,606 2.58 Inflow Area (Al Impervious 0.86 (ac) Turf 0.99 (ac) Void Ratios Storage Equiv. 1 0.50 (ft) 0.25 0.75 (ft) 0.4 0.13 (ft) 0.4 0.80 (ft) 0.4 0.40 (ft) 2.58 (ft) =1784 (sf) 436.00 434.50 434.25 434.00 431.00 430.67 428.67 427.67 80 (ft) 100 (ft) 0.80 No Baffle Required Pre -Treatment Cell 750 (sf) 1.00 (ft) 750 (cf) 691 (cf) bALZEQ ,ar�s SPECIFICATION #9 - BIORETENTION BASIN B WORKSHEET Design Level Level #2 PROJECT NAME: PROJECT #: DATE: BY: Timberland Park Apartments 34160034 1/10/2017 DKO BMP Sizing Data Transcribed Runoff Reduction Worksheet Inflow Area (A) Treatment Volume (Tv) Level #2 Impervious 5,224 (cf) Impervious 1.30 (ac) Level #2 Turf (cf) Turf 1.02 (ac) Treatment Level Treatment Volume Total Coefficient (Tv) TvBMP 1.25 * 5,224 (cf) = 6,529 (cf) Equivalent Storage Depth Void Ratios Storage Equiv. Surface Storage 0.50 (ft) 1 0.50 (ft) Bioretention Soil Media & Mulch 3.00 (ft) 0.25 0.75 (ft) Choker Stone 0.33 (ft) 0.4 0.13 (ft) Required Gravel Below Underdrain 1.00 (ft) 0.4 0.40 (ft) Additional Gravel 1.00 (ft) 0.4 0.40 (ft) Total Depth 5.83 (ft) 2.18 (ft) xequirea Nurrace Area Treatment Volume 6,529 = 2992 (sf) Equivalent Storage Depth 2.18 Pond Desien Elevations (ft Top of Bioretention Berm Top of Storage, High Flow Weir, Top of Riser P.T. Cell Low Flow Weir Top of Media Bottom of Media Bottom of Choker Stone Underdrain not used Bottom of Gravel Flow Path Pre -Treatment Measures Length of shortest flow path w/ >20% contributing DA Overall length Ratio Measure 1 Measure 2 Pre -Treatment Cell Design Design Cell Surface Area Design Cell Depth Provided Storage Required Storage (TvBMP*0.15) 424.00 422.50 422.25 422.00 419.00 418.67 416.67 80 (ft) 100 (ft) 0.80 No Baffle Required Grass Filter Strip Pre -Treatment Cell 640 (sf) 2.00 (ft) 1,280 (cf) 979 (cf)