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HomeMy WebLinkAboutWPO201800044 Calculations 2021-12-07SHIMP ENGINEERING, P.C. Design Focused Engineering December 7.2021 John Anderson, PE County of Albemarle Department of Community Development 401 McIntire Road, North Wing Charlottesville, Virginia22902 Regarding: ABC Block 1 Mass Grading -Major Amendment For Multifamily WP02018-00044 Major Amendment Dear John, Enclosed is the stormwater calculation packet for the ABC Block 1 Mass Grading - Major Amendment For Multifamily. This packet demonstrates the compliance with Albemarle County and Commonwealth of Virginia water quantity and quality regulations. Stormwater Management Design Summary To comply with applicable regulations, all onsite runoff is analyzed at three points of analysis (POA) as shown in the map below. CHANNEL POA 1 DRAINS TO PDA 2 BROOKDALE APTS. DETENTION POND (MANMADE CHANNEL) I CHANNEL POA 3 DRAINS THRU EX. PIPE TO NATURAL CHANNEL I`�M fl� SCALE: 1"=300' The strategy is to capture the majority of site runoff and utilize the onsite BMP's to treat runoff for both water quality and quantity. This treated runoff is discharged to POA 2 within a natural channel. The remainder of site runoff drains to POA 1 (the detention pond for the neighboring Brookdale Apartments) and POA 3 (the inlet of a culvert that runs under Old Lynchburg Road and drains into a natural channel. 912 E. High St. Charlottesville, VA 22902 1434.227.5140 1 shimp-engineering.com Runoff Quantity Narrative All runoff from this development ultimately discharges into two natural channels at POA 2 and POA 3. The stormwater management system was designed to release runoff in compliance with quantity regulations detailed in 9VAC25-870-66-B.3.a (channel protection for discharge to a natural channel by compliance with the energy balance equation) and 9VAC25-870-66-C.2.b (flood protection by reduction of the 10-yr storm event runoff). Specifically, this is achieved by utilizing the underground storage of the Onsite BMPs to detain runoff before discharge into POA 2. At POA 1 and POA 3, runoff complies with the energy balance equation because the runoff volume and peak flow rate to both of these points is less than the predeveloped condition. At these 2 POA's, both channel protection and flood protection are met without any treatment. Channel Protection Requirements per 9VAC25-870-66-B.3.a At POA 1 and POA 3, runoff complies with the energy balance equation and thus meets both manmade and natural channel analysis requirements. At POA 2, there is offsite runoff from Country Green Road which drains into the proposed stormwater management (SWM) system. This offsite runoff drains into the system due to the topography and layout of this adjacent road, and mixes with the onsite runoff. Compliance with the energy balance equation is only required for onsite runoff. Due to this condition, Shimp Engineering has analyzed for Energy Balance Equation (EBE) compliance by using what the Finn calls the Reduction Method. The energy balance equation specifies a certain Maximum Post -developed Flow Rate for onsite runoff. However, it is inaccurate to compute the Post -developed onsite runoff independent of the offsite runoff mixed in the system while still properly designing the BMP's. Thus, the reduction that is required for onsite runoff, equal to the Max. Qdeveloped minus Qpmdeveloped, was computed, and that difference is used as the regulatory parameter for the total runoff draining to the POA. So for runoff to POA 2, the SWM design must achieved a total runoff reduction (including both onsite and offsite runoff) that exceeds that reduction required by the energy balance equation for onsite runoff at each POA. Using this runoff reduction target as the regulatory parameter, Shimp Engineering designed and revised an underground stormwater management system. Shimp Engineering selected the ADS Stormtech Chambers and Isolator Row BMP's for the development's stormwater management systems. These BMP's are underground detention facilities which provide sediment filtration to achieve a 40% phosphorous reduction. Several other options were considered, including infiltration basins, large corrugated metal pipe (CMP) for underground detention, and biofiltration basins. Site constraints were not favorable to these other options. Insufficient soil permeability prohibited the use of an infiltration system. Lack of usable surface area and steep topography at the low points of the site prohibited the use of bioretention basins. Utility density and separation constraints from the multifamily development did not promote the use of underground CMP detention. While designing the Stormtech Chambers and Isolator ROW BMP, it was discovered that the flow reduction parameter from the Energy Balance Equation Reduction Method was so large that a 3" circular control orifice was not small enough to provide the required flow reduction. The BMP's have been designed to detain 1- yr storm runoff so that the 3" orifice is the only control outlet. The system was also upsized to provide lower head in the system to minimize peak flow rates. Despite these provisions, it was concluded that a 3" orifice was too large to allow the reduction rate required by the energy balance equation. A 3" orifice is typically considered to be the minimum BMP orifice size due to maintenance and performance concerns. Smaller orifices are prone to more frequent clogging. If the low -flow control orifice clogs, runoff would be forced through the larger outlet orifices at a higher flow rate, which would be counterproductive to low flow rates for channel protection. Since the design utilizes the County minimum 3" orifice but does not meet the energy balance equation reduction requirement, Shimp Engineering pursues a variance to the Energy Balance Equation at POA 2. This is requested based on the following achieved parameters: 1. Post -development peak runoff is less than 1.0 cfs. Achieved total peak flow rate to POA 2 is 0.70 cfs, compared to the 1.50 cfs pre -development peak flow rate. 2. Total Post -development peak runoff to POA 2 is reduced by 0.80 cfs from predevelopment runoff. The required reduction is 0.87 cfs. At POA 2, the postdevelopment flow rate is 53% lower than the predevelopment flow rate, and this strategy achieves 92% of the target EBE-generated reduction. 3. The minimum allowed 3" control orifice is provided. 4. All 1-year storm runoff is controlled by this 3" orifice. 5. Alternative BMP's were not effective options based on site constraints. The purpose of the variance is to pursue compliance with 9VAC25-870-66.3.b "In accordance with another methodology that is demonstrated by the VSMP authority to achieve equivalent results and is approved by the board." Albemarle County has concluded in other projects that a minimum 3" orifice size, along with proof of a reasonable reduction in the 1-yr storm peak runoff rate and peak runoff rates less than 1 cfs substantially constitute performance requirements to demonstrate channel protection. 1-Yr Runoff Reduction 1-Yr Runoff Required By ERE Reduction Achieved POA 2 0.87 cfs 0.80 cfs At POA 2, 92% of the target reduction rate is achieved with this design. The final total peak flow rate to POA 2 is 0.70 cfs, fully controlled by a single 3" orifice. Thus, we argue that for POA 2, alternate channel protection requirements are met. At all other POA's, the final post -developed 1-yr runoff is less than the Maximum allowed 1-yr runoff thus achieving the simple compliance with the Energy Balance Equation and 9VAC25-870-66-B.3.a. Max. Allowable 1-Yr 1-Yr Runoff Runoff Required By ERE Achieved POA 1 0.92 cfs 0.41 cfs POA 3 0.17 cfs 0.16 cfs Thus, it has been demonstrated that channel protection requirements are met at POA 1 and POA 3 because the energy balance equation is met at these two points. Flood Protection Requirements To meet flood protection requirements, all post -development runoff is released to natural channels prone to flooding at peak flow rates that are less than the pre -development peak flow rates, in compliance with 9VAC25-870-66-C.2.b. This was achieved at POA 1, 2, and 3. Enyneertn.z Design Due Diligence & SWMAnalvsisAssumpuons Shimp Engineering previously demonstrated in the first major amendment that the adjacent detention pond for Brookdale Apartments was designed based on the assumption that the pond's offsite area has a curve number of 81 (reference WPO 2017-00081, WPO plan sheet C.024, plot dated 01/29/2018; and associated SWM calculation packet page 27 hydrograph no. 15, report dated 12-12-2017). This plan shows 2.98 acres from the Block 1 Site draining into the pond. It has been established that this pond was designed to manage up to 2.98 acres of Block 1 with CN=81, however Shimp Engineering and the developer decided against discharging concentrated runoff into the pond. This design does propose to discharge onsite sheetflow runoff into this pond. This runoff will concentrate at the pond outfall at POA 1, thus this runoff was analyzed for EBE compliance in the section above. For due diligence analysis, post -development drainage area to the pond is 0.98 acres at CN=60. This is far below the pond design parameters. Since the post -development drainage area and curve number to the pond is less than the design area, runoff from this area which flows into the pond will not cause adverse downstream impacts. Since this pond routes both onsite and offsite runoff into the natural channel at POA 2, Shimp Engineering has made 2 modeling assumptions in the HydroCAD software to simulate the pond detention. 1. It is assumed that the pond will cause a 2-hr lag in the runoff peak for onsite runoff 2. It is assumed that the pond will cause a 50% reduction in the peak flow rate for onsite runoff These assumptions are reflected in the "Link" node 7L in the "Post Development" HydroCAD model. These were made based on familiarity with similar dry detention ponds, and represent conservative design parameters. These assumptions were made because as -built pond offsite drainage areas, land cover, and control structures are unknown. Runoff Quality Narrative To address runoff quality requirements set forth in 9VAC25-870-65, the site land cover information was entered into the VRRM Redevelopment Spreadsheet Version 3. This spreadsheet shows that the project requires a total phosphorous (TP) reduction of 4.80 lb/yr. To achieve that required TP reduction, two onsite Stormtech BMP's will provide treatment. These BMP's have an Isolator Row that achieves 40% TP removal through sediment filtration. BMP 1 will treat 1.02 lb/yr TP. condition. BMP 2 will treat 2.14 lb/yr TP. These combine for 3.16 Ib/yr TP. This leaves a total remaining treatment requirement of 1.64 Ib/yr TP. The owner will purchase 1.64 lbs of nutrient credits to cover this remaining amount. A letter of availability for this amount is included in the VSMP plan sheets. If you have any questions about this calculation packet please do not hesitate to contact me at: keane(a,shimp-engineering.com or by phone at 434-299-9843. Regards, Keane Rucker, EIT Shimp Engineering, PC Contents: SWM Quantity Requirements: Time of Concentration Calculations Pre-Dev Onsite For EBE HydroCAD Report Pre-Dev Total HydroCAD Report Post-Dev Onsite For EBE HydroCAD Report Post-Dev Total HydroCAD Report Energy Balance Equations SWM Quality Requirements: VRRM New Development Spreadsheets Independent Reports: Excerpt from NRCS Soils Report NOAA Precipitation Report SWM Quantity Requirements: Time of Concentration Calculations Pre-Dev Onsite For EBE HydroCAD Report Pre-Dev Total HydroCAD Report Post-Dev Onsite For EBE HydroCAD Report Post-Dev Total HydroCAD Report Energy Balance Equations ABC BLOCK 1 PreDev Time of Concentration Calculations Predev to POA 1 035 ft overland flow 5.7% slope 0.25 C-value 6.9 min 190 ft s. c. flow -grass 13.7% slope 1.8 fps velocity 1.8 min. 250ft channel 18.Oft height 1.5 min. TOC= 10.2 min. Seelye Chart NEH Figure 15-4 Kirpich Chart ABC BLOCK 1 PREDEV TOC NOMOGRAPHS T ee 0.225 0.42 5-0.19 L. -1.0 C nbaprvr to M., of Gnneentmtlon Part&34 Natrona, Engineering Handbook To=C)edano Flay Time, mmw F 1 = 1.er4h of ably. feet 35 TRAVEL TIME FOR CHANNEL FLOW (Kirpich Chart) Figure 15 t Velocity verses mope for etwllow .... tmtal&run a=Slope. Amyieel C = Ralipnol'C' Value far G..wNl Ch.Chm 600 30 M (feet) o.w Soo Paved 0.9 0.70 0.so 500 Tc (min.) 400 0.8 25 ns p.ao 200 300 0.7- ' j 2W J J 0.13 20 200 Soil Bare /04 _ \ \W \ PoorZ -r 0.5Z 100 S GriAverars�es\a 1.0 5� 80 �RK \ i \ W 70 0.2 \ 5.0 U 60 \\ ��� 10 20 j 40 p§ 10 co �' Z zo Z W U W z131 0.20 o.� o.ogWnv�50 o.oa 0eta9- a0a o.ol R a�.-.. Da 1DO L (feet) 0000 Example 50 5000Sula cote: (1) for use with natural channels; j c For paved channels, multipty 10 10 0.2 1000 E ~ z 5 £ 500 5 Y t OF e {, v "o �� ¢ k e ;i 1_pi oaos �veloeb(ere) 30 O u F a 20 fla+lp , "C" Volvo rtr Se leereo C,o o Crwocrer Oereee Gross 0. 215 0.25 7 00 1 1 TIME OF CONCENTRATION OF SMALL DRAINAGE BASINS Table 15-3 Equations and assumptions developed from figure 15-4 Fl-love Depth ManningMa Velocity equation Z7F1ser v3'6 0,0a. Weap 0.79 (n) (fie) roan 0 30 Poor Cress Swlaee 0:36 Pavement and small upland gullies 0.2 0.026 V=2o.323(s)efl Poe,ture 0.40 5 10 Bore Son 0.40 Parea G.90 Glasseda At rekv 09 0.050 V=16135(s)o° Nearly bare and untAIM(rnoMand flow); and alluvial fans to wesam mountain 0.2 Q. 11 V=9.906(s)a5 regiorvs Culavzted straight row crops 0.2 0.058 V=8.762(e)-" OVERLAND FLOW TIME Shortgrasspasture 0.2 0,073 V=6.962(s)-b Mun tru m tillage cmlthauon, contua or etaperopped, and woodlands 0.2 0.101 V=5.032(s)R° Forest wide heavy ground DRer and lay meadows 0.2 0.202 V=2.516(sye Source: VDOT Plate 5-3 LEGEND: PREDEV TOC TO POA 1 1S 4S 6S Pre Onsit To POA 1 Pre Onsit To POA 2 Pre Onsit To POA 3 77 3L v 5L 7L POA 1 POA 2 POA 3 S4 Reach Aon Lin k Pre-Dev EBE Pre Development ONSITE FOR EBE Type 1124-hr 1-yr Rainfall=3.05" Prepared by {enter your company name here} Printed 12/6/2021 HydroCADO 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Paqe 2 Time span=5.00-40.00 hrs, dt=0.04 hrs, 876 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method Subcatchment 1S: Pre Onsite To POA 1 Runoff Area=3.930 ac 0.00% Impervious Runoff Depth=0.29" Tc=10.2 min CN=58 Runoff=0.92 cfs 0.095 of Link 3L: POA 1 Inflow=0.92 cfs 0.095 of Primary=0.92 cfs 0.095 of Subcatchment 4S: Pre Onsite To POA 2 Runoff Area=0.290 ac 0.00% Impervious Runoff Depth=0.35" Tc=5.0 min CN=60 Runoff=0.13 cfs 0.008 of Link 5L: POA 2 Inflow=1.00 cfs 0.104 of Primary=1.00 cfs 0.104 of Subcatchment 6S: Pre Onsite To POA 3 Runoff Area=1.090 ac 0.00% Impervious Runoff Depth=0.21" Tc=5.0 min CN=55 Runoff=0.17 cfs 0.019 of Link 7L: POA 3 Inflow=0.17 cfs 0.019 of Primary=0.17 cfs 0.019 of Total Runoff Area = 5.310 ac Runoff Volume = 0.122 of Average Runoff Depth = 0.28" 100.00% Pervious = 5.310 ac 0.00% Impervious = 0.000 ac rut Pre-Dev EBE Pre Development ONSITE FOR EBE Type 1124-hr 1-yr Rainfall=3.05" Prepared by {enter your company name here} Printed 12/6/2021 HydroCAD9 9.10 s/n 07054 02011 HydroCAD Software Solutions LLC Pane 3 Subcatchment 1S: Pre Onsite To POA 1 Hydrograph 1 0 Runoff 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 I I I I I I 0.9z ag 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 I I I I I I I I I I I I I I I I I I I ylpe MI 124�hr 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 ' 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 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 RUlioff'Arl&6=3.930 c1d I I I I I I I I I I I I I I I I I I I I I I I I II I I I I I MiumQfi VQI0R�e-0,09$ of h6noff:bel I I=I).'12I 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 LL I I I I I I I I I I I I I I I I I I TC=10.2 rillh I I I I I I I I I I I I I � � I I I I I I �f -1•�� 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 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 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 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 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 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 I I I I I I I 0 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) Link 3L: POA 1 Hydrograph r-III I'ftflpNr ---- -"-*- r-�-" *-r-r-r-r-I--� ■ Inflow 1 osz a. ', ❑ Primary 092 ON ', Areia-3: 9 ',3O'ac'', 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) 11 Pre Development ONSITE FOR EBE Prepared by {enter vour comoanv name Pre-Dev EBE Type 11 24-hr 1-yr Rainfall=3.05" Printed 12/6/2021 Subcatchment 4S: Pre Onsite To POA 2 Hydrograph 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 I I I 1 -L-L-L J-J-J-J-J-J-J-1-L-L-L-L-L-L-I--I-J-J-J-J-J-1-1-1-L-1-L-L-L-I--I- I 01 r y1 ~`r0.13 ype-I 24-1-r�-y_ I h /- I I 0.12 11 RaitYf�lL-3.057- -F_{_i_i_i_4_F_F_F _I _I _I _I_y-y-y-{ I I I I I I I I I I I I I I I I I IJ, I I I-�I I--Q1 I I r I/��F I I'/ I�F +y I (II I} ��rn'off'^. V�V 29V WV -r-r-r-r �-�-i-r-r-r-r-r-r-r-r -r 1 r 01 1 1 1 1 1 1 1 1 1 1 1 1 ff 0.09 1I 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 no r r-r-r-r-r-r-r-1--r-r-1---y-yy'-T-T-r-rn-r-r-r-r-1 0� 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Runo1f_De�It �0a35'i_ -1--1--1- I_---------1--1- I- 1- 1-- ii 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 �TR 0.07 11 1 1 1 1 1 1 1_{1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 ITIr�S'Ain- -F 0.06/� -r-r-r-r 0.05 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1• 0.04 1I 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 -r-r-r-r- r-7-y-r-r-r-r-r-r-r-r-r-r-1--1-y--T-T-r-r-r-r-rT T T 0.03 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 T 1 1 7 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0.02 0.01 ' 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 2930 31 32 33 34 35 36 37 38 39 40 Time (hours) Link 5L: POA 2 Hydrograph 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) ■ RunoH ■ Inflow ❑ Primary IN Pre-Dev EBE Pre Development ONSITE FOR EBE Type 1124-hr 1-yr Rainfall=3.05" Prepared by {enter your company name here} Printed 12/6/2021 HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Pane 5 Subcatchment 6S: Pre Onsite To POA 3 Hydrograph -- - - - - - ----- - --------- -- - - - - - - - -------- 0.18 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 I I I I . RunoH __________________________________________ 0.n C18 0.17 I I I I I I I I I I I I I I I I I I I I I Ip I IA I I I -i _r_r _I__I__ i_ i _i i _i _I-----_I-_I V�1M--Y_ 0.16 '___L-------------------------------------- ll' ( -I -I - r 0.15 / IRaWfa[t=3-.G5"__ -r 0.14 / Iu 7� I 1 11 1 1 1 1 I 0.13 V11r6a _'I.09G j1d__ -r-r-r-r-I---1-l-1-T-r-r-r-r-r-r-I--I--I--I I- I -T -T -T r r r -r r I- 012 1 1 1 1 1 1 1 1 1 1 1 l` 1 pr 1 � 1/� I /� 1 1 I 1 1 1 I 1 I 1 1 1 I I 1 1 I I TT 0.11--+---'--'--"-__+_+_r_r_r_�_�_I__'__'__'___"-"+'^+'(r_jj, _+e+n_+_r_r-//�_'__ 1 1 1 1 1 1 1 1 1 1 1 1 Bulb,' Depth_-(L211,-- .V.. 0.1 _L _F _11I_ _J_J_J_+_+_L_f _4_L_L _I11_ 1_ ii 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I 1 6.09 _L-L-'--'--I- LL / 0.06 0.07 / II- 0.06 _L _L _L J_J_ J_J_J_1_1_L_L_L_L_L_I_J_J_J_J_J_J_1_1_1_L_L_L_L_I__I__I__ /I I I 1 I I 1 0.05 _L_L-'- '_J_ �-J_J_1_1_L_L_L_L_L-'_-'-'-J_J_J_�-1_L_1_1_L_L_L_'--'_-'-- 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0.04 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0.03 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 1 I 1 1 1 1 1 1 1 1 1 I 0.02 0.01 0 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) Link 7L: POA 3 --- -1- ■ ir11i0W ----J-'- -L-'-J-J-1-1-L-L-'--'-J-1-1-L-L----J-J-1-1-L----J-J-1- ■Prim erY 018 1 o.ncis 1 ------ o.n II_ cis-L-1--'-1-1-1-L-L-'--1-1-inn1#f Ir1``��-I,,--I(�I �-1- �Y-i!eIVJ ACi_ 0.17 _IL_li_i_ L_ L_I__1i_�_�!�!�wL!T 0.16 0.15 0.14 I-J-L- 0.13 012 6'11 ' ,' / -I- _L_I_J_J_J_L_L_L_I__I_J_J_1_L_L _I__I__I_J_1_L_L_I__I_J_J_J_ v 01 I -L-I-J_J_1_L_L_L_I_J_J_J_1_a_L-I--I-J_J_1_L_L_I__I_J_J_1- 3 009. 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 I 008 0.07 0.06 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 005 004 1 1 1 1 1 00 1 1 1 1 1 0.02 0.01 0 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) 13 iS 4S 6S Pre Onsit To POA 1 Pre Onsit To POA 2 Pre OnsiI o POA 3 a Pre Offsite To POA 1 POA 1 Subcat Reach Aon Llnk POA 2 POA 3 14 Pre-Dev TOTAL Pre Development Type 1124-hr 1-yr Rainfall=3.05" Prepared by {enter your company name here} Printed 12/6/2021 HydroCADO 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Page 2 Time span=5.00-40.00 hrs, dt=0.04 hrs, 876 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method Subcatchment 1S: Pre Onsite To POA 1 Runoff Area=3.930 ac 0.00% Impervious Runoff Depth=0.29" Tc=10.2 min CN=58 Runoff=0.92 cfs 0.095 of Subcatchment 2S: Pre Off site To POA 1 Runoff Area=0.170 ac 100.00% Impervious Runoff Depth>2.76" Tc=10.1 min CN=98 Runoff=0.64 cfs 0.039 of Link 3L: POA 1 Inflow=1.50 cfs 0.134 of Primary=1.50 cfs 0.134 of Subcatchment 4S: Pre Onsite To POA 2 Runoff Area=0.290 ac 0.00% Impervious Runoff Depth=0.35" Tc=5.0 min CN=60 Runoff=0.13 cfs 0.008 of Link 5L: POA 2 Inflow=1.59 cfs 0.143 of Primary=1.59 cfs 0.143 of Subcatchment 6S: Pre Onsite To POA 3 Runoff Area=1.090 ac 0.00% Impervious Runoff Depth=0.21" Tc=5.0 min CN=55 Runoff=0.17 cfs 0.019 of Link 7L: POA 3 Inflow=0.17 cfs 0.019 of Primary=0.17 cfs 0.019 of Total Runoff Area = 5.480 ac Runoff Volume = 0.162 of Average Runoff Depth = 0.35" 96.90% Pervious = 5.310 ac 3.10% Impervious = 0.170 ac IN Pre-Dev TOTAL Pre Development Type 1124-hr 10-yr Rainfall=5.58" Prepared by {enter your company name here} Printed 12/6/2021 HydroCADO 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Page 3 Time span=5.00-40.00 hrs, dt=0.04 hrs, 876 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method Subcatchment 1S: Pre Onsite To POA 1 Runoff Area=3.930 ac 0.00% Impervious Runoff Depth=1.50" Tc=10.2 min CN=58 Runoff=8.49 cfs 0.492 of Subcatchment 2S: Pre Off site To POA 1 Runoff Area=0.170 ac 100.00% Impervious Runoff Depth>5.17" Tc=10.1 min CN=98 Runoff=1.18 cfs 0.073 of Link 3L: POA 1 Inflow=9.64 cfs 0.565 of Primary=9.64 cfs 0.565 of Subcatchment 4S: Pre Onsite To POA 2 Runoff Area=0.290 ac 0.00% Impervious Runoff Depth=1.65" Tc=5.0 min CN=60 Runoff=0.86 cfs 0.040 of Link 5L: POA 2 Inflow=10.23 cfs 0.605 of Primary=10.23 cfs 0.605 of Subcatchment 6S: Pre Onsite To POA 3 Runoff Area=1.090 ac 0.00% Impervious Runoff Depth=1.28" Tc=5.0 min CN=55 Runoff=2.42 cfs 0.117 of Link 7L: POA 3 Inflow=2.42 cfs 0.117 of Primary=2.42 cfs 0.117 of Total Runoff Area = 5.480 ac Runoff Volume = 0.721 of Average Runoff Depth = 1.58" 96.90% Pervious = 5.310 ac 3.10% Impervious = 0.170 ac rry 6S PostDev Unmanaged to P Al 7L POA1 iS PostDev NSITE to BM 1 3P —p 5P 4S PostDev NSITE to BM 2 BMP1 BM 2 9L �POA2 8$ PostDev Unmanaged to POA 2 Subcat Reach Aon Llnk 10S PostDev Un anaged to PriA3 11L POA 3 17 Post-Dev EBE Post Development ONSITE FOR EBE Type 1124-hr 1-yr Rainfall=3.05" Prepared by {enter your company name here} Printed 12/6/2021 HydroCADO 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Paqe 2 Time span=0.00-48.00 hrs, dt=0.04 hrs, 1201 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method Subcatchment 1S: PostDev ONSITE to Runoff Area=0.830 ac 80.00% Impervious Runoff Depth=2.12" Tc=5.0 min CN=91 Runoff=3.08 cfs 0.146 of Pond 3P: BMP 1 Peak Elev=461.69' Storage=2,619 cf Inflow=3.08 cfs 0.146 of Outflow=0.38 cfs 0.146 of Subcatchment 4S: PostDev ONSITE to Runoff Area=2.830 ac 80.00% Impervious Runoff Depth=2.12" Tc=5.0 min CN=91 Runoff=10.51 cfs 0.499 of Pond 5P: BMP 2 Peak Elev=454.50' Storage=15,768 cf Inflow=10.85 cfs 0.646 of Outflow=0.49 cfs 0.617 of Subcatchment 6S: PostDev Unmanaged to Runoff Area=0.900 ac 11.11% Impervious Runoff Depth=0.35" Tc=5.0 min UI Adjusted CN=60 Runoff=0.41 cfs 0.026 of Link 7L: POA 1 x 0.50 delayed by 60.0 min Inflow=0.41 cfs 0.026 of Primary=0.21 cfs 0.013 of Secondary=0.21 cfs 0.013 of Subcatchment 8S: PostDev Unmanaged to Runoff Area=0.240 ac 12.50% Impervious Runoff Depth=0.29" Tc=5.0 min UI Adjusted CN=58 Runoff=0.08 cfs 0.006 of Link 9L: POA 2 Inflow=0.70 cfs 0.636 of Primary=0.70 cfs 0.636 of Subcatchment 10S: PostDev Unmanaged Runoff Area=0.500 ac 12.00% Impervious Runoff Depth=0.29" Tc=5.0 min UI Adjusted CN=58 Runoff=0.16 cfs 0.012 of Link 11 L: POA 3 Inflow=0.16 cfs 0.012 of Primary=0.16 cfs 0.012 of Total Runoff Area = 5.300 ac Runoff Volume = 0.690 of Average Runoff Depth = 1.56" 41.17% Pervious = 2.182 ac 58.83% Impervious = 3.118 ac it l Post-Dev EBE Post Development ONSITE FOR EBE Type 1124-hr 1-yr Rainfall=3.05" Prepared by {enter your company name here} Printed 12/6/2021 HydroCAD® 9.10 s/n 07054 02011 HydroCAD Software Solutions LLC Paae 3 Subcatchment 1S: PostDev ONSITE to BMP 1 Hydrograph I I I 1 i i I I I 1 i I I 1 i i I I I 1 ■ Runoff 1 3-1 _OB cis i i 1 1i -Y 3 ' Type II; 2 -hr -yr 11 ��1111��111 1111 Fial6fall"3.05" 1 1 1 1 RWnbffl Area=0.830 ad ��111 ��1111��111� 1111 ---- '1, J, i �k ff1'1�/pl4rrre�0.' 4� Elf- ;, z o 1 1 1 1 hunoff ; Depth T2.1,121," Tc=5.0 tnih 1 1 1 1 N=g1 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 Time (hours) Pond 3P: BMP 1 Hydrograph 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 ■ Inflow 11 11 s.rea. 11 11 11 1 1 1 ❑ Primary 1lrtflow 11 Area. 0;830 Iliac 3 1 1 Peak F-l0_46'1.69' Storgge=2'1,619 cf 1 1 1 1 ' 2- 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 Time (hours) 19 Post-Dev EBE Post Development ONSITE FOR EBE Type 1124-hr 1-yr Rainfall=3.05" Prepared by {enter vour comoanv name here) Printed 12/6/2021 Subcatchment 4S: PostDev ONSITE to BMP 2 Hydrogreph 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 - �--'--J--,--1-----L--L--1---1--J--1--1--i--L--�--'-- '--J--i--i--i--�-- ■Runoff I I I I I I I I I I I I I I I I I I I I I I 1U.51 L�5 --,--- - --, --,------- ----�I,--�I,--I,Typ611;2t1hr-t=yr- --r--�--,--,--7 r--r--�---�--,--Y--Y--r--r--r--�-Raiitfiatt�3.A5"`- 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 I I I I I I -- J- - J--1--1--1%nd#fiAreti_28t; 30-a- 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 I I I I I I I I I I I I I I I I I ----;--;- ;--;-------;--;--;--;--tiunafFiD ptFrT2.121`- 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 I I I I I -- -- -- - -------'-- -- -- --A-- ---------Tc=15:0-tnlh - 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 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 r I I I I I I I I I I I I I I I I I I I I r I 1 1 I I I I --'I -r - -r I I,--1--1--T --r --r I I,--,--T--T--r-- 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 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 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 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 I I I I I I I I I I I I 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 Time (hours) Pond 5P: BMP 2 Hydrogreph -- -- --- -- --------- ,- -- ---- -- -- -- --- 12------i--� ■Irrllow , , ' I I mesas ■ Primary 11 J__L_Wow: Areaz;3, 011ac- I I POEkk Ele�4. I-45 I I 50!_ I I I I Moral � i�768 ,IIII IIIIIIII I c 'IIII IIIIIIII yl 8 -- --- 6. 'III. IIIIIIIIIIIIIIIII I I I I I I I I- I I I I I I I 5 I-1--7--1-r--r--r-�--,--r--r--r-r--r--r--r-�--,--r--r--r- I I I I I I I I I 4-. 3 2- 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 Time (hours) pill Post-Dev EBE Post Development ONSITE FOR EBE Type 1124-hr 1-yr Rainfall=3.05" Prepared by {enter vour comoanv name here) Printed 12/6/2021 0.1 0.1 Subcatchment 6S: PostDev Unmanaged to POA 1 _I - I --r-r-r--r- �RunoH `__J--4--1 o.H 4{8 --'i-J1--------1`--'i --11----�--YY�Pe-1[,�-1�ti-�Y�'-- �/In �/I�` --'`-`--J--+--` --II--------Ir ----`--I'--+--`--`--I--J--+--+--LRQin•Y[L"WG5L-- --II--------_II_ RIYY���� NI*rr*��I 1//((��--I 1 ,1 1 1 I 1 ;--1r--1-- 1 1 1 1 1 1 1 1 1 RilinbirAie=�LOII�E 1 1 1 1 1 1 1 ` J I -r J -7 -Y -r --J1--;- -I -r -Y -T -r -I $�yagif Vsa[4me =p � -- r hunWI be,ptK-tI9-,5'w- I I I I I I I I�=�-- I I I I I I I I I I I y J- yYTryT ;- 1 1 --;U(A*Ste��N�60--- 1 1 1 1 1 1 1 1 1 1 I t__ 1 1 __1__�__Y__Tr,tTrYTt__1___ I I I I 1 1 1 1 1 I I 1 1 1 I I 1 1 1 1 I I 1 1 1 I I 1 1 1 I I I -T -t -1 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 Time (hours) Link 7L: POA 1 , , I I I I I I I I I I I I ____r--r-�--r----r--r-r--r-r--i-r--r--r-r-r-r--r-r--r--I--r- I ■Inflow oa1418 ■ Primary I - -- --- -- -- - - I1__7_ ■Secondary _ 1__r__1__r_,__r__I__r__I__r__r_,__r__I__ r__I__ r__r_r_ XL��_ I r_r__r__I__r__1__r__r_r_ I I I I I I I I I I I I I I I I I I I I I I I I --r--I---0.21--r--1--r—rr--r-r--r----r--I-- r -- r--I--r- I I I -r--r--r-rr_-I__r__I__r__r_�__r_ I I I I I I I I I I I I I -1 -I -T -F-'1 -r 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 Time (hours) 21 Post-Dev EBE Post Development ONSITE FOR EBE Type 1124-hr 1-yr Rainfall=3.05" Prepared by {enter vour comoanv name here) Printed 12/6/2021 0.1 Subcatchment 8S: PostDev Unmanaged to POA 2 I --I- 0.081}8 __J__1__L__I__ -__J__L__L__I__ 11'1.241�r=yr- I I I _II I I I I I I I I I I I RII��„I l*' 1"I /(� I I - I� ainfiIA VAW' - I I I I I I I I I I I I I I I I I I I I I �--J--L--L--1--1--J--J--L I I I I I I I I I I I I I -RUndfUAted=U.240 at; - --'--J--�--�--L I I I I --11- I --J--�--L--'-- -- --1, I I --1- I -- I I i--_ I -- --RuFt� --J--J--L-- I /�Iu1MO=006-4- r Ir T r r Flu_ noff b_ep_tl_��Q.2.9;`_-_ ' I I I I I I I _I _y _{ _f/�_I TIc=SA-Mift- I I I I I I I I I I I I I I I L ----=,I -----r ----- --I- ----III r-- I I 1 1 1 I I I I I I I I I I jUlj A¢l4s�eo CNN 54 --- -- ----I ---I-----------I ---I------1--- r r,-r -rr r,r-r- 1 1 1 I I 1 1 1 I I 1 1 1 I 1 1 1 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 I I _ _______I__I__I__ I___I__ I I I I I I I 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 Time (hours) Link 9L: POA 2 Hydrograph I--a--a- -`-J FE rrilOW i ones _------- ____ ______ __ Prim ary 0,70 cis _ I I I I I I I I I I I I I I I I I I I I I I r__r__r_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 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 I I I I 1 I i , i I I I I I I I I I I I I I _I _1 _a _ti _F _I _J _♦ � F _I _J _1 _F _I _i _F _I _a 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 I I I I y__T__, 7__�__ �__y__ TT__r_T_ y__r__ I__�__ , L__L 1__L__I__J__1__L_J__1 J__1__L_J__1__L__I__J__ I I I I I I I I I I I I I ' --1�--r--I-rI--r---r--r--I--�--r--r- �-- I I 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 oft 0 2 Time (hours) VK Post-Dev EBE Post Development ONSITE FOR EBE Type 1124-hr 1-yr Rainfall=3.05" Prepared by {enter vour comoanv name here) Printed 12/6/2021 0.01 0.01 Subcatchment 10S: PostDev Unmanaged to POA 3 - ;-- -- - -;- ;- -- - -;- ;-- --- -; - -;- - --I_ I I I I I I I I I I I I I I I I I I I I I __ ■Runoff I I I I I I I I I I I I I I I I I I I I I I 0.18 CI8 ,-- ' 'Pe , -, T r , T1 J[:24Phr-1-Yr-- - - - -I -I ---T I --'I-- 'I--7---- r - I I I I I I I I I III II --I---I--y--t--Y--I--Y--y--�--Y--I---I--y--t--�--Y--I---'--y--�--Y--I--- --a- ftndffI+AreA_-0.s00a�- I I I I I I I I I I I I I I I I I I I I I L L L -I �iane##-111©eptkt�a9" I I LI I II III -T -r I I , -T -T-��aS�iI , -T-T^�-C�-I%6�I I _+I I__1I II__II I________I__I__I___I___I__I__I__I __I___ I___I__I__ I__ I __ 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 Time (hours) Link 11 L: POA 3 ------------- 0 Primary ,. ' pis cm I I I I I I I I I I I I I --r-�--r--r I I I- I I I I I I --r--r-�--r--r-�--r--r--r-,--r--r--I—,--r--r-,-- 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 _T__r__� I I I I I I __r__�__r__r__r_r__r__r__i I I I I I I I I I I I _,__T__r__i__T__ r__ I__,__ , I __I__-__r__- __r__�__7__r_4_7__1__1 1__r_4 r__r__I__�__ I I I --r-r-r--r I I I I I I I I I I I I I _' -y -T _r-Y � I -Y -Y -' _y -T -Y -' _7 I I I I I I I I I I I I I I I I 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 Time (hours) 23 PostDev Offsite to 1 6S PostDev U managed to P Al 7L POA 1 iS PostDev NSITE to \ ,BM 1 7J X7 4S PostDev NSITE to BM 2 3P -p 5P BMP1 (i� PostDev Unmanaged to POA 2 Subcat Reach Aon Llnk BM 2 POA 2 10S PostDev U managed to P A3 li 1L POA 3 24 Post-Dev TOTAL Post Development Type 1124-hr 1-yr Rainfall=3.05" Prepared by {enter your company name here} Printed 12/6/2021 HydroCADO 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Page 2 Time span=0.00-48.00 hrs, dt=0.04 hrs, 1201 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method Subcatchment 1S: PostDev ONSITE to Runoff Area=0.830 ac 80.00% Impervious Runoff Depth=2.12" Tc=5.0 min CN=91 Runoff=3.08 cfs 0.146 of Subcatchment 2S: PostDev Off site to Runoff Area=0.170 ac 100.00% Impervious Runoff Depth=2.82" Tc=5.0 min CN=98 Runoff=0.75 cfs 0.040 of Pond 3P: BMP 1 Peak Elev=462.21' Storage=3,396 cf Inflow=3.83 cfs 0.186 of Outflow=0.42 cfs 0.186 of Subcatchment 4S: PostDev ONSITE to Runoff Area=2.830 ac 80.00% Impervious Runoff Depth=2.12" Tc=5.0 min CN=91 Runoff=10.51 cfs 0.499 of Pond 5P: BMP 2 Peak Elev=454.69' Storage=16,460 cf Inflow=10.88 cfs 0.686 of Outflow=0.50 cfs 0.657 of Subcatchment 6S: PostDev Unmanaged to Runoff Area=0.900 ac 11.11% Impervious Runoff Depth=0.35" Tc=5.0 min UI Adjusted CN=60 Runoff=0.41 cfs 0.026 of Link 7L: POA 1 x 0.50 delayed by 60.0 min Inflow=0.41 cfs 0.026 of Primary=0.21 cfs 0.013 of Secondary=0.21 cfs 0.013 of Subcatchment 8S: PostDev Unmanaged to Runoff Area=0.240 ac 12.50% Impervious Runoff Depth=0.29" Tc=5.0 min UI Adjusted CN=58 Runoff=0.08 cfs 0.006 of Link 9L: POA 2 Inflow=0.70 cfs 0.676 of Primary=0.70 cfs 0.676 of Subcatchment 10S: PostDev Unmanaged Runoff Area=0.500 ac 12.00% Impervious Runoff Depth=0.29" Tc=5.0 min UI Adjusted CN=58 Runoff=0.16 cfs 0.012 of Link 11 L: POA 3 Inflow=0.16 cfs 0.012 of Primary=0.16 cfs 0.012 of Total Runoff Area = 5.470 ac Runoff Volume = 0.730 of Average Runoff Depth = 1.60" 39.89% Pervious = 2.182 ac 60.11% Impervious = 3.288 ac W Post-Dev TOTAL Post Development Type 1124-hr 1-yr Rainfall=3.05" Prepared by {enter your company name here} Printed 12/6/2021 HydroCADO 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Page 3 Summary for Subcatchment 1 S: PostDev ONSITE to BMP 1 Runoff = 3.08 cfs @ 11.96 hrs, Volume= 0.146 af, Depth= 2.12" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type II 24-hr 1-yr Rainfall=3.05" Area (ac) CN Description 0.830 91 Apartments. 80% imp. HSG B 0.166 20.00% Pervious Area 0.664 80.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, TOC Summary for Subcatchment 2S: PostDev Offsite to BMP 1 Runoff = 0.75 cfs @ 11.95 hrs, Volume= 0.040 af, Depth= 2.82" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type II 24-hr 1-yr Rainfall=3.05" Area (ac) CN 0.170 98 Paved parking, HSG B 0.170 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, TOC Summary for Pond 3P: BMP 1 Inflow Area = 1.000 ac, 83.40% Impervious, Inflow Depth = 2.24" for 1-yr event Inflow = 3.83 cfs @ 11.96 hrs, Volume= 0.186 of Outflow = 0.42 cfs @ 12.30 hrs, Volume= 0.186 af, Atten= 89%, Lag= 20.9 min Primary = 0.42 cfs @ 12.30 hrs, Volume= 0.186 of Routing by Dyn-Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Peak Elev= 462.21' @ 12.30 hrs Surf.Area= 1,950 sf Storage= 3,396 cf Plug -Flow detention time= 84.9 min calculated for 0.186 of (100% of inflow) Center -of -Mass det. time= 84.5 min ( 874.5 - 790.1 ) %zj Post-Dev TOTAL Post Development Type 1124-hr 1-yr Rainfall=3.05" Prepared by {enter your company name here} Printed 12/6/2021 HydroCADO 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Paqe 4 Volume Invert Avail.Storage Storage Description #1 459.00' 4,479 cf Custom Stage Data (Prismatic) Listed below (Recalc) 15,600 cf Overall - 4,402 cf Embedded = 11,198 cf x 40.0% Voids #2 461.00' 4,260 cf StormTech MC-4500 x 40 Inside #1 Effective Size= 90.4"W x 60.0"H => 26.46 sf x 4.031 = 106.5 cf Overall Size= 100.0"W x 60.0"H x 4.33'L with 0.31' Overlap #3 461.00' 143 cf StormTech MC-4500 Cap x 4 Inside #1 Effective Size= 63.5"W x 59.0"H => 15.25 sf x 2.341 = 35.7 cf Overall Size= 90.2"W x 59.4"H x 2.921 with 0.58' Overlap 8,881 cf Total Available Storage Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 459.00 1,950 0 0 467.00 1,950 15,600 15,600 Device Routing Invert Outlet Devices #1 Primary 458.00' 18.0" Round 18" HDPE L= 105.0' Ke= 0.300 Inlet / Outlet Invert= 458.00' / 453.00' S= 0.0476'/' Cc= 0.900 n= 0.012 #2 Device 1 459.00' 3.0" Vert. Orifice/Grate C= 0.600 #3 Device 1 466.00' 4.0' long Sharp -Crested Rectangular Weir 2 End Contraction(s) 8.0' Crest Height Primary OutFlow Max=0.42 cfs @ 12.30 hrs HW=462.21' TW=453.89' (Dynamic Tailwater) t1=18" HDPE (Passes 0.42 cfs of 18.27 cfs potential flow) �2=Orifice/Grate (Orifice Controls 0.42 cfs @ 8.46 fps) 3=Sharp-Crested Rectangular Weir ( Controls 0.00 cfs) Summary for Subcatchment 4S: PostDev ONSITE to BMP 2 Runoff = 10.51 cfs @ 11.96 hrs, Volume= 0.499 af, Depth= 2.12" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type II 24-hr 1-yr Rainfall=3.05" Area (ac) CN 2.830 91 Apartments, 80% imp, HSG B 0.566 20.00% Pervious Area 2.264 80.00% Impervious Area Tc Length Slope Velocity Capacity Description 5.0 Direct Entry, TOC Ph Post-Dev TOTAL Post Development Type 1124-hr 1-yr Rainfall=3.05" Prepared by (enter vour comoanv name here) Printed 12/6/2021 Summary for Pond 5P: BMP 2 Inflow Area = 3.830 ac, 80.89% Impervious, Inflow Depth = 2.15" for 1-yr event Inflow = 10.88 cfs @ 11.96 hrs, Volume= 0.686 of Outflow = 0.50 cfs @ 15.24 hrs, Volume= 0.657 at, Atten= 95%, Lag= 197.2 min Primary = 0.50 cfs @ 15.24 hrs, Volume= 0.657 of Routing by Dyn-Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Peak Elev= 454.69' @ 15.24 hrs Surf.Area= 5,060 sf Storage= 16,460 cf Plug -Flow detention time= 414.7 min calculated for 0.656 of (96% of inflow) Center -of -Mass det. time= 390.9 min ( 1,211.4 - 820.4) Volume Invert Avail.Storage Storage Description #1 449.00' 12,169 cf Custom Stage Data (Prismatic) Listed below (Recalc) 43,060 cf Overall - 12,638 cf Embedded = 30,422 cf x 40.0% Voids #2 452.00' 12,353 cf StormTech MC-4500 x 116 Inside #1 Effective Size= 90.4"W x 60.0"H => 26.46 sf x 4.03'L = 106.5 cf Overall Size= 100.0"W x 60.0"H x 4.331 with 0.31' Overlap #3 452.00' 286 cf StormTech MC-4500 Cap x 8 Inside #1 Effective Size= 63.5"W x 59.0"H => 15.25 sf x 2.34'L = 35.7 cf Overall Size= 90.2"W x 59.4"H x 2.921 with 0.58' Overlap #4 448.75' 655 cf 42.0" D x 68.1'L 42" Pipe Storage S= 0.0037 T 25,462 cf Total Available Storage Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 449.00 100 0 0 450.00 5,060 2,580 2,580 458.00 5,060 40,480 43,060 Device Routing Invert Outlet Devices #1 Primary 448.55' 30.0" Round 30" HDPE L= 20.0' Ke= 0.600 Inlet / Outlet Invert= 448.55' / 446.50' S= 0.1025 '/' Cc= 0.900 n= 0.012 #2 Device 1 450.00' 3.0" Vert. Orifice/Grate C= 0.600 #3 Device 1 455.00' 36.0 deg x 2.50' rise Vee Notch C= 2.58 #4 Device 1 457.50' 6.0' long Weir Plate in A5 2 End Contraction(s) 6.2' Crest Height #5 Primary 458.50' 6.0' long Overflow DI-7 Grate 2 End Contraction(s) 9.5' Crest Height Primary OutFlow Max=0.50 cfs @ 15.24 hrs HW=454.69' TW=0.00' (Dynamic Tailwater) 1-30" HDPE (Passes 0.50 cfs of 48.98 cfs potential flow) Lr2=Orifice/Grate (Orifice Controls 0.50 cfs @ 10.28 fps) F-3=Vee Notch ( Controls 0.00 cfs) Weir Plate in A5 ( Controls 0.00 cfs) =Overflow DI-7 Grate ( Controls 0.00 cfs) 28 Post-Dev TOTAL Post Development Type 1124-hr 1-yr Rainfall=3.05" Prepared by {enter your company name here} Printed 12/6/2021 HydroCADO 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Page 6 Summary for Subcatchment 6S: PostDev Unmanaged to POA 1 Runoff = 0.41 cfs @ 11.99 hrs, Volume= 0.026 af, Depth= 0.35" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type II 24-hr 1-yr Rainfall=3.05" Area (ac) CN Description 0.800 58 Woods/grass comb., Good, HSG B 0.100 98 Unconnected pavement, HSG B 0.900 62 Weighted Average, UI Adjusted CN = 60 0.800 88.89% Pervious Area 0.100 11.11 % Impervious Area 0.100 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, TOC Summary for Link X: POA 1 Inflow Area = 0.900 ac, 11.11% Impervious, Inflow Depth = 0.35" for 1-yr event Inflow = 0.41 cfs @ 11.99 hrs, Volume= 0.026 of Primary = 0.21 cfs @ 12.99 hrs, Volume= 0.013 af, Atten= 50%, Lag= 60.0 min Secondary = 0.21 cfs @ 12.99 hrs, Volume= 0.013 of Primary outflow = Inflow x 0.50 delayed by 60.0 min, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Summary for Subcatchment 8S: PostDev Unmanaged to POA 2 Runoff = 0.08 cfs @ 12.00 hrs, Volume= 0.006 af, Depth= 0.29" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type II 24-hr 1-yr Rainfall=3.05" Area (ac) CN Description 0.030 98 Unconnected pavement. HSG B 0.240 60 Weighted Average, UI Adjusted CN = 58 0.210 87.50% Pervious Area 0.030 12.50% Impervious Area 0.030 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, TOC 0i-1 Post-Dev TOTAL Post Development Type 1124-hr 1-yr Rainfall=3.05" Prepared by {enter your company name here} Printed 12/6/2021 HydroCADO 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Paqe 7 Summary for Link 9L: POA 2 Inflow Area = 4.970 ac, 64.95% Impervious, Inflow Depth > 1.63" for 1-yr event Inflow = 0.70 cfs @ 12.99 hrs, Volume= 0.676 of Primary = 0.70 cfs @ 12.99 hrs, Volume= 0.676 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Summary for Subcatchment 10S: PostDev Unmanaged to POA 3 Runoff = 0.16 cfs @ 12.00 hrs, Volume= 0.012 af, Depth= 0.29" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type II 24-hr 1-yr Rainfall=3.05" Area (ac) CN Description 0.060 98 Unconnected pavement, HSG B 0.440 55 Woods, Good, HSG B 0.500 60 Weighted Average, UI Adjusted CN = 58 0.440 88.00% Pervious Area 0.060 12.00% Impervious Area 0.060 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, TOC Summary for Link 11 L: POA 3 Inflow Area = 0.500 ac, 12.00% Impervious, Inflow Depth = 0.29" for 1-yr event Inflow = 0.16 cfs @ 12.00 hrs, Volume= 0.012 of Primary = 0.16 cfs @ 12.00 hrs, Volume= 0.012 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs 01 Post-Dev TOTAL Post Development Type 1124-hr 10-yr Rainfall=5.58" Prepared by {enter your company name here} Printed 12/6/2021 HydroCADO 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Page 8 Time span=0.00-48.00 hrs, dt=0.04 hrs, 1201 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method Subcatchment 1S: PostDev ONSITE to Runoff Area=0.830 ac 80.00% Impervious Runoff Depth=4.55" Tc=5.0 min CN=91 Runoff=6.30 cfs 0.314 of Subcatchment 2S: PostDev Off site to Runoff Area=0.170 ac 100.00% Impervious Runoff Depth=5.34" Tc=5.0 min CN=98 Runoff=1.38 cfs 0.076 of Pond 3P: BMP 1 Peak Elev=465.58' Storage=7,757 cf Inflow=7.68 cfs 0.390 of Outflow=0.60 cfs 0.390 of Subcatchment 4S: PostDev ONSITE to Runoff Area=2.830 ac 80.00% Impervious Runoff Depth=4.55" Tc=5.0 min CN=91 Runoff=21.49 cfs 1.072 of Pond 5P: BMP 2 Peak Elev=457.50' Storage=24,447 cf Inflow=21.98 cfs 1.462 of Outflow=8.90 cfs 1.433 of Subcatchment 6S: PostDev Unmanaged to Runoff Area=0.900 ac 11.11% Impervious Runoff Depth=1.65" Tc=5.0 min UI Adjusted CN=60 Runoff=2.68 cfs 0.124 of Link 7L: POA 1 x 0.50 delayed by 60.0 min Inflow=2.68 cfs 0.124 of Primary=1.34 cfs 0.062 of Secondary=1.34 cfs 0.062 of Subcatchment 8S: PostDev Unmanaged to Runoff Area=0.240 ac 12.50% Impervious Runoff Depth=1.50" Tc=5.0 min UI Adjusted CN=58 Runoff=0.64 cfs 0.030 of Link 9L: POA 2 Inflow=9.17 cfs 1.525 of Primary=9.17 cfs 1.525 of Subcatchment 10S: PostDev Unmanaged Runoff Area=0.500 ac 12.00% Impervious Runoff Depth=1.50" Tc=5.0 min UI Adjusted CN=58 Runoff=1.34 cfs 0.063 of Link 11 L: POA 3 Inflow=1.34 cfs 0.063 of Primary=1.34 cfs 0.063 of Total Runoff Area = 5.470 ac Runoff Volume = 1.679 of Average Runoff Depth = 3.68" 39.89% Pervious = 2.182 ac 60.11% Impervious = 3.288 ac 31 Post-Dev TOTAL Post Development Type 1124-hr 10-yr Rainfall=5.58" Prepared by {enter your company name here} Printed 12/6/2021 HvdroCADO 9.10 s/n 07054 © 2011 HvdroCAD Software Solutions LLC Paae 9 Summary for Subcatchment 1 S: PostDev ONSITE to BMP 1 Runoff = 6.30 cfs @ 11.95 hrs, Volume= 0.314 af, Depth= 4.55" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type II 24-hr 10-yr Rainfall=5.58" Area (ac) CN Description 0.830 91 Apartments. 80% imp. HSG B 0.166 20.00% Pervious Area 0.664 80.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, TOC Summary for Subcatchment 2S: PostDev Offsite to BMP 1 Runoff = 1.38 cfs @ 11.95 hrs, Volume= 0.076 af, Depth= 5.34" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type II 24-hr 10-yr Rainfall=5.58" Area (ac) CN 0.170 98 Paved parking, HSG B 0.170 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, TOC Summary for Pond 3P: BMP 1 Inflow Area = 1.000 ac, 83.40% Impervious, Inflow Depth = 4.68" for 10-yr event Inflow = 7.68 cfs @ 11.95 hrs, Volume= 0.390 of Outflow = 0.60 cfs @ 12.47 hrs, Volume= 0.390 af, Atten= 92%, Lag= 31.1 min Primary = 0.60 cfs @ 12.47 hrs, Volume= 0.390 of Routing by Dyn-Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Peak Elev= 465.58' @ 12.47 hrs Surf.Area= 1,950 sf Storage= 7,757 cf Plug -Flow detention time= 132.9 min calculated for 0.390 of (100% of inflow) Center -of -Mass det. time= 133.1 min ( 904.8 - 771.7 ) 00a Post-Dev TOTAL Post Development Type 1124-hr 10-yr Rainfall=5.58" Prepared by {enter your company name here} Printed 12/6/2021 HvdroCADO 9.10 s/n 07054 © 2011 HvdroCAD Software Solutions LLC Paae 10 Volume Invert Avail.Storage Storage Description #1 459.00' 4,479 cf Custom Stage Data (Prismatic) Listed below (Recalc) 15,600 cf Overall - 4,402 cf Embedded = 11,198 cf x 40.0% Voids #2 461.00' 4,260 cf StormTech MC-4500 x 40 Inside #1 Effective Size= 90.4"W x 60.0"H => 26.46 sf x 4.031 = 106.5 cf Overall Size= 100.0"W x 60.0"H x 4.33'L with 0.31' Overlap #3 461.00' 143 cf StormTech MC-4500 Cap x 4 Inside #1 Effective Size= 63.5"W x 59.0"H => 15.25 sf x 2.341 = 35.7 cf Overall Size= 90.2"W x 59.4"H x 2.921 with 0.58' Overlap 8,881 cf Total Available Storage Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 459.00 1,950 0 0 467.00 1,950 15,600 15,600 Device Routing Invert Outlet Devices #1 Primary 458.00' 18.0" Round 18" HDPE L= 105.0' Ke= 0.300 Inlet / Outlet Invert= 458.00' / 453.00' S= 0.0476'/' Cc= 0.900 n= 0.012 #2 Device 1 459.00' 3.0" Vert. Orifice/Grate C= 0.600 #3 Device 1 466.00' 4.0' long Sharp -Crested Rectangular Weir 2 End Contraction(s) 8.0' Crest Height Primary OutFlow Max=0.60 cfs @ 12.47 hrs HW=465.58' TW=456.51' (Dynamic Tailwater) t1=18" HDPE (Passes 0.60 cfs of 24.92 cfs potential flow) �2=Orifice/Grate (Orifice Controls 0.60 cfs @ 12.24 fps) 3=Sharp-Crested Rectangular Weir ( Controls 0.00 cfs) Summary for Subcatchment 4S: PostDev ONSITE to BMP 2 Runoff = 21.49 cfs @ 11.95 hrs, Volume= 1.072 af, Depth= 4.55" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type II 24-hr 10-yr Rainfall=5.58" Area (ac) CN 2.830 91 Apartments, 80% imp, HSG B 0.566 20.00% Pervious Area 2.264 80.00% Impervious Area Tc Length Slope Velocity Capacity Description 5.0 Direct Entry, TOC 33 Post-Dev TOTAL Post Development Type 1124-hr 10-yr Rainfall=5.58" Preoared by (enter vour comDanv name here) Printed 12/6/2021 Summary for Pond 5P: BMP 2 Inflow Area = 3.830 ac, 80.89% Impervious, Inflow Depth = 4.58" for 10-yr event Inflow = 21.98 cfs @ 11.96 hrs, Volume= 1.462 of Outflow = 8.90 cfs @ 12.07 hrs, Volume= 1.433 af, Atten= 59%, Lag= 6.6 min Primary = 8.90 cfs @ 12.07 hrs, Volume= 1.433 of Routing by Dyn-Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Peak Elev= 457.50' @ 12.07 hrs Surf.Area= 5,060 sf Storage= 24,447 cf Plug -Flow detention time= 310.0 min calculated for 1.432 of (98% of inflow) Center -of -Mass det. time= 298.6 min ( 1,111.2 - 812.6) Volume Invert Avail.Storage Storage Description #1 449.00' 12,169 cf Custom Stage Data (Prismatic) Listed below (Recalc) 43,060 cf Overall - 12,638 cf Embedded = 30,422 cf x 40.0% Voids #2 452.00' 12,353 cf StormTech MC-4500 x 116 Inside #1 Effective Size= 90.4"W x 60.0"H => 26.46 sf x 4.03'L = 106.5 cf Overall Size= 100.0"W x 60.0"H x 4.331 with 0.31' Overlap #3 452.00' 286 cf StormTech MC-4500 Cap x 8 Inside #1 Effective Size= 63.5"W x 59.0"H => 15.25 sf x 2.34'L = 35.7 cf Overall Size= 90.2"W x 59.4"H x 2.921 with 0.58' Overlap #4 448.75' 655 cf 42.0" D x 68.1'L 42" Pipe Storage S= 0.0037 T 25,462 cf Total Available Storage Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 449.00 100 0 0 450.00 5,060 2,580 2,580 458.00 5,060 40,480 43,060 Device Routing Invert Outlet Devices #1 Primary 448.55' 30.0" Round 30" HDPE L= 20.0' Ke= 0.600 Inlet / Outlet Invert= 448.55' / 446.50' S= 0.1025 '/' Cc= 0.900 n= 0.012 #2 Device 1 450.00' 3.0" Vert. Orifice/Grate C= 0.600 #3 Device 1 455.00' 36.0 deg x 2.50' rise Vee Notch C= 2.58 #4 Device 1 457.50' 6.0' long Weir Plate in A5 2 End Contraction(s) 6.2' Crest Height #5 Primary 458.50' 6.0' long Overflow DI-7 Grate 2 End Contraction(s) 9.5' Crest Height Primary OutFlow Max=8.71 cfs @ 12.07 hrs HW=457.47' TW=0.00' (Dynamic Tailwater) 1-30" HDPE (Passes 8.71 cfs of 61.38 cfs potential flow) Lr2=Orifice/Grate (Orifice Controls 0.64 cfs @ 13.05 fps) F-3=Vee Notch (Weir Controls 8.06 cfs @ 4.06 fps) Weir Plate in A5 ( Controls 0.00 cfs) =Overflow DI-7 Grate ( Controls 0.00 cfs) U Post-Dev TOTAL Post Development Type 1124-hr 10-yr Rainfall=5.58" Prepared by {enter your company name here} Printed 12/6/2021 HvdroCADO 9.10 s/n 07054 © 2011 HvdroCAD Software Solutions LLC Paae 12 Summary for Subcatchment 6S: PostDev Unmanaged to POA 1 Runoff = 2.68 cfs @ 11.97 hrs, Volume= 0.124 af, Depth= 1.65" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type II 24-hr 10-yr Rainfall=5.58" Area (ac) CN Description 0.800 58 Woods/grass comb., Good, HSG B 0.100 98 Unconnected pavement, HSG B 0.900 62 Weighted Average, UI Adjusted CN = 60 0.800 88.89% Pervious Area 0.100 11.11 % Impervious Area 0.100 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, TOC Summary for Link X: POA 1 Inflow Area = 0.900 ac, 11.11 % Impervious, Inflow Depth = 1.65" for 10-yr event Inflow = 2.68 cfs @ 11.97 hrs, Volume= 0.124 of Primary = 1.34 cfs @ 12.97 hrs, Volume= 0.062 af, Atten= 50%, Lag= 60.0 min Secondary = 1.34 cfs @ 12.97 hrs, Volume= 0.062 of Primary outflow = Inflow x 0.50 delayed by 60.0 min, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Summary for Subcatchment 8S: PostDev Unmanaged to POA 2 Runoff = 0.64 cfs @ 11.97 hrs, Volume= 0.030 af, Depth= 1.50" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type II 24-hr 10-yr Rainfall=5.58" Area (ac) CN Description 0.030 98 Unconnected pavement. HSG B 0.240 60 Weighted Average, UI Adjusted CN = 58 0.210 87.50% Pervious Area 0.030 12.50% Impervious Area 0.030 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, TOC Oily Post-Dev TOTAL Post Development Type 1124-hr 10-yr Rainfall=5.58" Prepared by {enter your company name here} Printed 12/6/2021 HvdroCADO 9.10 s/n 07054 © 2011 HvdroCAD Software Solutions LLC Paae 13 Summary for Link 9L: POA 2 Inflow Area = 4.970 ac, 64.95% Impervious, Inflow Depth > 3.68" for 10-yr event Inflow = 9.17 cfs @ 12.06 hrs, Volume= 1.525 of Primary = 9.17 cfs @ 12.06 hrs, Volume= 1.525 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Summary for Subcatchment 10S: PostDev Unmanaged to POA 3 Runoff = 1.34 cfs @ 11.97 hrs, Volume= 0.063 af, Depth= 1.50" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type II 24-hr 10-yr Rainfall=5.58" Area (ac) CN Description 0.060 98 Unconnected pavement, HSG B 0.440 55 Woods, Good, HSG B 0.500 60 Weighted Average, UI Adjusted CN = 58 0.440 88.00% Pervious Area 0.060 12.00% Impervious Area 0.060 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, TOC Summary for Link 11 L: POA 3 Inflow Area = 0.500 ac, 12.00% Impervious, Inflow Depth = 1.50" for 10-yr event Inflow = 1.34 cfs @ 11.97 hrs, Volume= 0.063 of Primary = 1.34 cfs @ 11.97 hrs, Volume= 0.063 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs 01 Post-Dev TOTAL Post Development Type 1124-hr 100-yr Rainfall=9.16" Prepared by {enter your company name here} Printed 12/6/2021 HydroCADO 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Page 14 Time span=0.00-48.00 hrs, dt=0.04 hrs, 1201 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method Subcatchment 1S: PostDev ONSITE to Runoff Area=0.830 ac 80.00% Impervious Runoff Depth=8.07" Tc=5.0 min CN=91 Runoff=10.77 cfs 0.558 of Subcatchment 2S: PostDev Off site to Runoff Area=0.170 ac 100.00% Impervious Runoff Depth=8.92" Tc=5.0 min CN=98 Runoff=2.27 cfs 0.126 of Pond 3P: BMP 1 Peak Elev=467.11' Storage=8,881 cf Inflow=13.04 cfs 0.685 of Outflow=14.83 cfs 0.685 of Subcatchment 4S: PostDev ONSITE to Runoff Area=2.830 ac 80.00% Impervious Runoff Depth=8.07" Tc=5.0 min CN=91 Runoff=36.73 cfs 1.904 of Pond 5P: BMP 2 Peak Elev=458.86' Storage=25,462 cf Inflow=50.92 cfs 2.588 of Outflow=49.90 cfs 2.559 of Subcatchment 6S: PostDev Unmanaged to Runoff Area=0.900 ac 11.11% Impervious Runoff Depth=4.23" Tc=5.0 min UI Adjusted CN=60 Runoff=6.98 cfs 0.317 of Link 7L: POA 1 x 0.50 delayed by 60.0 min Inflow=6.98 cfs 0.317 of Primary=3.49 cfs 0.158 of Secondary=3.49 cfs 0.158 of Subcatchment 8S: PostDev Unmanaged to Runoff Area=0.240 ac 12.50% Impervious Runoff Depth=3.98" Tc=5.0 min UI Adjusted CN=58 Runoff=1.75 cfs 0.080 of Link 9L: POA 2 Inflow=51.70 cfs 2.797 of Primary=51.70 cfs 2.797 of Subcatchment 10S: PostDev Unmanaged Runoff Area=0.500 ac 12.00% Impervious Runoff Depth=3.98" Tc=5.0 min UI Adjusted CN=58 Runoff=3.65 cfs 0.166 of Link 11 L: POA 3 Inflow=3.65 cfs 0.166 of Primary=3.65 cfs 0.166 of Total Runoff Area = 5.470 ac Runoff Volume = 3.150 of Average Runoff Depth = 6.91" 39.89% Pervious = 2.182 ac 60.11% Impervious = 3.288 ac MFA Post-Dev TOTAL Post Development Type 1124-hr 100-yr Rainfall=9.16" Prepared by {enter your company name here} Printed 12/6/2021 HvdroCADO 9.10 s/n 07054 © 2011 HvdroCAD Software Solutions LLC Paae 15 Summary for Subcatchment 1 S: PostDev ONSITE to BMP 1 Runoff = 10.77 cfs @ 11.95 hrs, Volume= 0.558 af, Depth= 8.07" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type II 24-hr 100-yr Rainfall=9.16" Area (ac) CN Description 0.830 91 Apartments. 80% imp. HSG B 0.166 20.00% Pervious Area 0.664 80.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, TOC Summary for Subcatchment 2S: PostDev Offsite to BMP 1 Runoff = 2.27 cfs @ 11.95 hrs, Volume= 0.126 af, Depth= 8.92" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type II 24-hr 100-yr Rainfall=9.16" Area (ac) CN 0.170 98 Paved parking, HSG B 0.170 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, TOC Summary for Pond 3P: BMP 1 Inflow Area = 1.000 ac, 83.40% Impervious, Inflow Depth = 8.22" for 100-yr event Inflow = 13.04 cfs @ 11.95 hrs, Volume= 0.685 of Outflow = 14.83 cfs @ 11.97 hrs, Volume= 0.685 af, Atten= 0%, Lag= 1.1 min Primary = 14.83 cfs @ 11.97 hrs, Volume= 0.685 of Routing by Dyn-Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Peak Elev= 467.11' @ 11.97 hrs Surf.Area= 1,950 sf Storage= 8,881 cf Plug -Flow detention time= 108.8 min calculated for 0.685 of (100% of inflow) Center -of -Mass det. time= 108.4 min ( 867.2 - 758.8 ) 38 Post-Dev TOTAL Post Development Type 1124-hr 100-yr Rainfall=9.16" Prepared by {enter your company name here} Printed 12/6/2021 HvdroCADO 9.10 s/n 07054 @ 2011 HvdroCAD Software Solutions LLC Paae 16 Volume Invert Avail.Storage Storage Description #1 459.00' 4,479 cf Custom Stage Data (Prismatic) Listed below (Recalc) 15,600 cf Overall - 4,402 cf Embedded = 11,198 cf x 40.0% Voids #2 461.00' 4,260 cf StormTech MC-4500 x 40 Inside #1 Effective Size= 90.4"W x 60.0"H => 26.46 sf x 4.031 = 106.5 cf Overall Size= 100.0"W x 60.0"H x 4.33'L with 0.31' Overlap #3 461.00' 143 cf StormTech MC-4500 Cap x 4 Inside #1 Effective Size= 63.5"W x 59.0"H => 15.25 sf x 2.341 = 35.7 cf Overall Size= 90.2"W x 59.4"H x 2.921 with 0.58' Overlap 8,881 cf Total Available Storage Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 459.00 1,950 0 0 467.00 1,950 15,600 15,600 Device Routing Invert Outlet Devices #1 Primary 458.00' 18.0" Round 18" HDPE L= 105.0' Ke= 0.300 Inlet / Outlet Invert= 458.00' / 453.00' S= 0.0476'/' Cc= 0.900 n= 0.012 #2 Device 1 459.00' 3.0" Vert. Orifice/Grate C= 0.600 #3 Device 1 466.00' 4.0' long Sharp -Crested Rectangular Weir 2 End Contraction(s) 8.0' Crest Height Primary OutFlow Max=13.08 cfs @ 11.97 hrs HW=466.99' TW=458.81' (Dynamic Tailwater) t1=18" HDPE (Passes 13.08 cfs of 23.66 cfs potential flow) �2=Orifice/Grate (Orifice Controls 0.66 cfs @ 13.50 fps) 3=Sharp-Crested Rectangular Weir (Weir Controls 12.42 cfs @ 3.30 fps) Summary for Subcatchment 4S: PostDev ONSITE to BMP 2 Runoff = 36.73 cfs @ 11.95 hrs, Volume= 1.904 af, Depth= 8.07" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type II 24-hr 100-yr Rainfall=9.16" Area (ac) CN 2.830 91 Apartments, 80% imp, HSG B 0.566 20.00% Pervious Area 2.264 80.00% Impervious Area Tc Length Slope Velocity Capacity Description 5.0 Direct Entry, TOC ON Post-Dev TOTAL Post Development Type 1124-hr 100-yr Rainfall=9.16" Preoared by (enter vour comDanv name here) Printed 12/6/2021 Summary for Pond 5P: BMP 2 Inflow Area = 3.830 ac, 80.89% Impervious, Inflow Depth = 8.11" for 100-yr event Inflow = 50.92 cfs @ 11.97 hrs, Volume= 2.588 of Outflow = 49.90 cfs @ 11.97 hrs, Volume= 2.559 A Atten= 2%, Lag= 0.1 min Primary = 49.90 cfs @ 11.97 hrs, Volume= 2.559 of Routing by Dyn-Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Peak Elev= 458.86' @ 11.97 hrs Surf.Area= 5,060 sf Storage= 25,462 cf Plug -Flow detention time= 207.9 min calculated for 2.557 of (99% of inflow) Center -of -Mass det. time= 201.3 min ( 992.9 - 791.6) Volume Invert Avail.Storage Storage Description #1 449.00' 12,169 cf Custom Stage Data (Prismatic) Listed below (Recalc) 43,060 cf Overall - 12,638 cf Embedded = 30,422 cf x 40.0% Voids #2 452.00' 12,353 cf StormTech MC-4500 x 116 Inside #1 Effective Size= 90.4"W x 60.0"H => 26.46 sf x 4.03'L = 106.5 cf Overall Size= 100.0"W x 60.0"H x 4.331 with 0.31' Overlap #3 452.00' 286 cf StormTech MC-4500 Cap x 8 Inside #1 Effective Size= 63.5"W x 59.0"H => 15.25 sf x 2.34'L = 35.7 cf Overall Size= 90.2"W x 59.4"H x 2.921 with 0.58' Overlap #4 448.75' 655 cf 42.0" D x 68.1'L 42" Pipe Storage S= 0.0037 T 25,462 cf Total Available Storage Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 449.00 100 0 0 450.00 5,060 2,580 2,580 458.00 5,060 40,480 43,060 Device Routing Invert Outlet Devices #1 Primary 448.55' 30.0" Round 30" HDPE L= 20.0' Ke= 0.600 Inlet / Outlet Invert= 448.55' / 446.50' S= 0.1025 '/' Cc= 0.900 n= 0.012 #2 Device 1 450.00' 3.0" Vert. Orifice/Grate C= 0.600 #3 Device 1 455.00' 36.0 deg x 2.50' rise Vee Notch C= 2.58 #4 Device 1 457.50' 6.0' long Weir Plate in A5 2 End Contraction(s) 6.2' Crest Height #5 Primary 458.50' 6.0' long Overflow DI-7 Grate 2 End Contraction(s) 9.5' Crest Height Primary OutFlow Max=48.34 cfs @ 11.97 hrs HW=458.83' TW=0.00' (Dynamic Tailwater) 1-30" HDPE (Passes 44.61 cfs of 66.59 cfs potential flow) 2=Orifice/Grate (Orifice Controls 0.70 cfs @ 14.21 fps) 3=Vee Notch (Orifice Controls 14.33 cfs @ 7.05 fps) =Weir Plate in A5 (Weir Controls 29.58 cfs @ 3.87 fps) =Overflow DI-7 Grate (Weir Controls 3.73 cfs @ 1.89 fps) 40 Post-Dev TOTAL Post Development Type 1124-hr 100-yr Rainfall=9.16" Prepared by {enter your company name here} Printed 12/6/2021 HvdroCADO 9.10 s/n 07054 © 2011 HvdroCAD Software Solutions LLC Paae 18 Summary for Subcatchment 6S: PostDev Unmanaged to POA 1 Runoff = 6.98 cfs @ 11.96 hrs, Volume= 0.317 af, Depth= 4.23" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type II 24-hr 100-yr Rainfall=9.16" Area (ac) CN Description 0.800 58 Woods/grass comb., Good, HSG B 0.100 98 Unconnected pavement, HSG B 0.900 62 Weighted Average, UI Adjusted CN = 60 0.800 88.89% Pervious Area 0.100 11.11 % Impervious Area 0.100 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, TOC Summary for Link X: POA 1 Inflow Area = 0.900 ac, 11.11 % Impervious, Inflow Depth = 4.23" for 100-yr event Inflow = 6.98 cfs @ 11.96 hrs, Volume= 0.317 of Primary = 3.49 cfs @ 12.96 hrs, Volume= 0.158 af, Atten= 50%, Lag= 60.0 min Secondary = 3.49 cfs @ 12.96 hrs, Volume= 0.158 of Primary outflow = Inflow x 0.50 delayed by 60.0 min, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Summary for Subcatchment 8S: PostDev Unmanaged to POA 2 Runoff = 1.75 cfs @ 11.96 hrs, Volume= 0.080 af, Depth= 3.98" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type II 24-hr 100-yr Rainfall=9.16" Area (ac) CN Description 0.030 98 Unconnected pavement. HSG B 0.240 60 Weighted Average, UI Adjusted CN = 58 0.210 87.50% Pervious Area 0.030 12.50% Impervious Area 0.030 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, TOC 41 Post-Dev TOTAL Post Development Type 1124-hr 100-yr Rainfall=9.16" Prepared by {enter your company name here} Printed 12/6/2021 HvdroCADO 9.10 s/n 07054 © 2011 HvdroCAD Software Solutions LLC Paae 19 Summary for Link 9L: POA 2 Inflow Area = 4.970 ac, 64.95% Impervious, Inflow Depth = 6.75' for 100-yr event Inflow = 51.70 cfs @ 11.97 hrs, Volume= 2.797 of Primary = 51.70 cfs @ 11.97 hrs, Volume= 2.797 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Summary for Subcatchment 10S: PostDev Unmanaged to POA 3 Runoff = 3.65 cfs @ 11.96 hrs, Volume= 0.166 af, Depth= 3.98" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type II 24-hr 100-yr Rainfall=9.16" Area (ac) CN Description 0.060 98 Unconnected pavement, HSG B 0.440 55 Woods, Good, HSG B 0.500 60 Weighted Average, UI Adjusted CN = 58 0.440 88.00% Pervious Area 0.060 12.00% Impervious Area 0.060 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, TOC Summary for Link 11 L: POA 3 Inflow Area = 0.500 ac, 12.00% Impervious, Inflow Depth = 3.98" for 100-yr event Inflow = 3.65 cfs @ 11.96 hrs, Volume= 0.166 of Primary = 3.65 cfs @ 11.96 hrs, Volume= 0.166 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs EK ABC Block 1 - 1 Yr, 24 Hr Storm Comparison: Odneioceds I.F. *(QPre-De.eloped*RVPre-D loped)/RVoe lewd Qde. lop d5 (%ore d*RVFm red)/RVD...ioced Pre Onsite Drainage Area = 3.93 ac POA 1 Onsite Runoff: Post Onsite Drainage Area = 0.90 ac Qwe-de.eiopea = 0.92 (page to) I.F. = 0.9 RVPre-oa,ewpea = 0.095 (page to) Max Ode lopes = 0.92 cis RVDe xio,d = 0.026 (page 18) Since the Achieved 1-yr postdev peak flow rate Is 0.41 cfs, which is less than the Max. allowable developed flow rate, Runoff at this POA is compliant with the Energy Balance Equation per 9VAC25-870-66-B.3.a. POA 1 is in a natural channel prone to flooding. Runoff to this point is compliant with 9VAC25-870-66-C.2.b because the 10-yr peak runoff is reduced. 10-Yr Predev Runoff = 8.49 cis, 10-yr Postdev Runoff = 2.68 cis. Energy Balance Equation Summary for POA 2 ABC Block 1- 1 Yr, 24 Hr Storm Comparison: Qae.eioced5 I.F. *(QPre-De„eloped*RVPre--Load)/RVx-I.,a Qde. loceds (%ore d*RVF. red)/RVDe.eiold Pre Onsite Drainage Area = 4.22 ac POA 2 Onsite Runoff: Post Onsite Drainage Area = 4.80 ac Qprede.eiopea = (page 1o) I.F. = 0.8 RVPre-Dnewpea = (page'0) Max Ode lopes = 0.13 cis RVx-I.,d = PO1.649(page 18) PDA 1 is in a natural channel prone to flooding. Runoff to this point is compliant with 9VAC25-870-66-B.3.a because the total runoff to this point is reduced by an amount exceeding the reduction required by the entergy balance equation. See Note to the right. Site complies with 9VAC25-870-66-C(2)b because the 10-yr peak runoff is reduced. Energy Balance Equation Summary for POA 3 ABC Block 1- 1 Yr, 24 Hr Storm Comparison: Oae.eiopea� I.F.'(QPre-o elm ea*RVPro-x. loced)/RVD -Load Qde-ioped5(QFor.d*RVFm red)/RVa,<10ced Pre Onsite Drainage Area = 1.09 ac POA 3 Onsite Runoff: Post Onsite Drainage Area = 0.50 ac Qwe-de.ewpea = 0.17(page 1o) I.F. = 0.9 RVPre-oarcwpea = 0.019 (page 10) Max Ode lopes = 0.17 cfs RVx. Io,d = 0.012 (page 16) Since the Achieved 1-yr postdev peak flow rate Is 0.16 cfs, which is less than the Max. allowable developed flow rate, Runoff at this POA is compliant with the Energy Balance Equation per 9VAC25-870-66-B.3.a. POA 1 is in a natural channel prone to flooding. Runoff to this point is compliant with 9VAC25-870-66-C.2.b because the 10-yr peak runoff is reduced. 10-Yr Predev Runoff = 2.42 cfs, 10-yr Postdev Runoff =1.34 cfs. meet Energy Balance Requirements, duce Flow @ PDA 1 by: (Op,,. -Max Qom„) = required reduction @ POA 1.00 - 0.13 = 0.87 cfs required ACHIEVED REDUCTION AT PDA 1: 0.80 ds NOT ACHIEVED Achieved Total Runoff (includingOffsite PREDEV POSTDEV Q fe= 1.50 (page 15) Q ost= 0.70 (page 25) Qpfe= 9.64 (page 16) Qpost= 9.17 (page 31) 1-YR 10-YR 1-YR Flow 10-YR Flow Reduction Reduction 0.80 0.47 Note: This SWM Strategy provides 78 % of the required reduction required by the energy balance equation (0.68/0.87) and reducces the total 1-year peak runoff to POA 2 by 49 % (1.38 cfs to 0.70 cfs). Based on these results, a waiver to the energy balance equation is requested. This waiver is based on the fact that postdeveloped runoff is significantly reduced using best practices for the development with a minimum 3" low -flow control orifice. Additional peak flow runoff would require smaller orifice sizes, which would be more prone to clogging. 43 SWM Quality Requirements: VRRM New Development Spreadsheets U11 Pmine Name: ABC Block l Mana Gradi.- Mapr Amentlmem (ar MURhmily Dare: IV6M21 .., Linear Development Vrojen? No it Project (Treatment Volume and Loads) Enter Total Disturhed Area(mman) i SAG Tunhl-eNumaq®aemrnr wee/ma g uroerv�ouxcnnrmunl Land Lover Load mlma, dmwwan sraracuavUrmxl weemMnemnenl nnana e u cmlareeal wapeudmlautl o.zo om Namgemd imi can Wool Mao om avanpeaanl meat p 1. Treatment Volume and Nutrient Lead nrneoe lamavawme eal u o.aws o.tw nrneoevelnlaerlumnvamne kaee 63T1 4,6xn we-scerAgmana TP load Ilb/wl 1.00 2.91 --avavmr,emdPa•m layary..l .Pa nn 111 No) m.max/arepapmida�opreedeaeapmema r gpenio and P-P= oar nA. �mP.wnnxrma.i nd 1.33 tam Inamman tW rexersummaryYue fans No oiexyocen svatteedoo cm —onra nrna." 01. m nageevevl wngnmd n. t.m o.m ,loo, mvn rnvl a.aa ratavarweud xlnpemwv ar®1-1 am rwlvmauragxem am T-- lume u.x9a f aear varNmme kgLw W.. Pon areXgnam m lone 9.11 (lb/rrl ao'aa°�. aon-.1 ealuea rmrxoeamrnsr rn DZ,Cam an Came) o.m wadme gNrvaY o.m xrn oat nanReTuocvxr land i.m wadnad ar loam o.m manage— ]mL MPandma ann) om _. n.lwpmwp ones v u l wlm Treatment Volume and Nutrient Load TP Load ReluDion Required llb/yrj I qRN a --1 Naalnmvvkvvn lame) m n4eMxMwnrnbal a.m w.alodermn m,a beano... Road-"red., D.se unul..aw,xrn a.0 lvpm Anna Wren 116n,) lib/vrl mearvi ..x CS1 vRRM Pow, sPmmHaie v s Ax NGCK t Drainage Area A Dolma Mea A laMCover aves( ASoila BSoila Cbils Oww Poramm'Smm(a,fd Maayeennpua) It12 [am laoral 0.71 Stormwater Best Manaeement Practices (RR= Runoff Reduction) Total PM1aspM1aus Available for Removal In DA A(RIFT) 1.59 Post Development Treatment Volume In DA A (ft3)1 2536 Selen from draodemn Rsh- Practice RunoX Redutllm Credit l%I MarugNTUrf C(Acr Rrea IxreQ ImpeMaus Area Area (acres) Volumefram Uptream practice lftal RunoffDomnstremp a Redutlian lRl Remaining RunoXe') I%sI TodI Ads Treatment Volume lftsl Phosphorus Removal Elri[ienN (%) Phosphorus Wad from Upstream Practiced (lb) Untreated PM1aspM1arus(lb) to Females (lb) Phosphorus Remavetl Bg PnEirellbl Remaining PM1aspM1arus Load Ilb) mand to be Employed a.,..as ...I (',a, w8 . uu Foalaz(,Par xs) zasimpeoBmnnemonm A/F sane Ism,al, 3b.simpk Oeaanneanonta [/GSons sm, all pe,ifinaane lent ne c/o rune( lspecewl omWint, FalahV... alxl W a,aiofmml aooaz(leal z f To Fain Game, n. al(sm, Ml nor az lsxm, Ml W i Fa X z o ineaur .-brNla5pM) - tarpama, I'mvaaaum tDrese aypanme, a. ,nm a memmlxl (Stoop41 a 0 0 21 An An - 3 b. Peonmee Pnvemmtn(saaazl a.Goveeaanb An Stalrepa.'x31 a,.Gmss ChamellVR5oibn MI . GasOunidxlJ�Gvnp-sAmendal5oils eperfaee5pawl a. sa.e ATVvs JIm 0 1 0 2. An - s,a.lean(1,AIR 0 0 0 a. An - e ume'veraversoon(snesne Mnxl _ . an h. Ra,aeme, to or Weloem ovens. o aminmm,nl5tass) b. mnmmioln2estaxdl a, 0 a I 1 11 an a-N,S. Extended Detention Fred (PRI a. xl lzpamsl .VIDIC(lies.) 11 0 a 0 0 1, An - 9a. sheemw to eonssnnun wu,"sons Sparta) or, 9uemw to comervaun a me, 4o so.a due, xzl .,.FW.emaa to vegetatm Fhe, salt, A Soik„ comer.-emF MI's 0paxz Awl sD G G G G D Dm GAn G.No -A, TOTAL IMPERWWSCOVERIREATEOIa[I U.UD AREA CXECK: OK. TOTAL MAXAGEOTURF AREATREATEOIa[I U.A, AREA CXECK: OK. TOTAM UXOFFREDUCTOX IN OA.A(fLa)U TJTALPXOSPXORUSAVAILABLEFORREMOVALIX OA.AI1b/yr) 1.59 TOTAL PHOSPHORUS REMOVED WITH RUNOFF REDUCTION PRACTICES IN DA. A I1DIET D.GO XOSPXORUS REMAINING AFTER APPLYING RUNOFF REDUCTION PMCTICES IN OA.R(Ib/yr) l.. SEE WATER QUALITY COMPLIANCE TAB 1. Fltering Pntti[ee(na RRl a. et Ponan(spe,nal - ]3b.Vast Panealbased Hem Give#l<I 0 1 1 s I -aso- u. overPom n(sPa alai - - asset Pont 0(casol Plain, Istaalal - - te-rabrNarmree➢eatmem Deets lab.MN-Fhenng lab. Mamfiameal T—re-1 Mse-Ha s, - .c Manuhmae! Tmonem .-re, road.IMME IWS COVER TREATED (a[) 0]1 AREACRECK: OIL TOTNMARAGEDTIRFAREATREAMD(m) 0.121 AREA CHECK: OR. TOTAL PHOSPHORUS REMOVAL REQUIRED DR SITE IIb/yr) 0.R0 TLFTAL PHOSPHORUS AVAILABLE FOR REMOVAL IN D.A. A IIb/yr) 159 TOTAL PHOSPHORUS REMOVED WITHOUT RUHOFi REDUCTION PRACTICES IN D.A. AI1b/yr) 1.02 TOTAL PHOSPHORUS REMOVED WITH RUNOFF REDUCTION PMCTCFSM D.A. A IIb/yr) 0.AT TOTAL PHOSPHORUS LOAD REDUCTION ACHIEVED I N DA.RI1DIET 1.U2 TOTAL PHOSPHORUS REMAINING AMR APPLHHG MP LOAD REWCTIOHS IN D.A. A(Ib/yr) 0.52 SEE WATER QUALITY COMPLIANCE TAB FOR SITE COMPLIANCE CALCULATIONS NITROGEN REMOVED WITH RUNOFF REDUCTION PRACTCESIN A. A(Ib/yr) 0.00 NITRGGEN REMOVED WITHOUT RUNOFF REDUCTION PMCFICES NO.A.A(ID/yr) 0.00 TMAL NITROGEN REMOVED IX OA.A(Ib/yr) a.. 101 M 46 vww ReO.. snoewm n age eLoeK t Drainage Area B Drainage Area A Lane Cover laveel Asoile BsoO, CsoO, 0Soils Tons's Land Goes, Rv wom/apesespeap,rel ono o.m Monoged"Per-) o.as D.aG os0 farerlatresl 2.37 1 2.37 0.95 otal 2A3 Stormwater Best Management Practices (RR= Runoff Reduction) Total Phosphorus Available for Removal in D.A. B(Ib/yr) 5.34 Post Derelopment Treatment Volume in D.A. B IN) B,SD] 5n1en form e,00ewun.il Runoff Mandita Turf Volumeamm RunaX Remaining Tat t Phosphorus Phosphorus Untreated Phosphorus pta[[IC! mrshCredit C(Agia Come Credit Upstreossup, 0.e RmeIunuff Treatment Land from PM1aspM1arus Rammed Phosphorus Downstream Pntllm to be [reElt%u (aveQ .2Rom) Area (avesl s praM¢e (Net III) (rye) Volume (Rol INRemmal VolumeIN)Elri¢ienryl%) Upstream LwEm praRice(Ib) Fresh-(B) batl (Ibl Land(m) Employed PraRices (Ib) Pra[tice(Ib) I. mare lemallsPetusl ah.vgmrea Roorxzlsmsaslin and ze. Sim Pla Dkmnnmaon m NR %ik p a h. Sim Pa Dmonnmann m cn ses, (sui - ens rise, Par, as Pe, ,par. —no (—.ad LAD eeiia)(1, and Vs.,o a, Ross Dna{ a., nm,Raonat Quit so Dry iaseco-�alnns) ar m Ram Games al, 1 (Spas. sureentrusenson 2 Dpas.1 ah Mo Rana — xmemmg Isom' xGl TOO m Nam Urban 82, , io�lsms xR, uPcesai. AI .. Coins a aeemeneairper ]1 Th.Pemr-aleprosa emm(spmn) 11 L I- • a. nss Chinni N8 Vol, Quay e) • . ass Closest C/D sol,(s EU c, ssetunrelwlmmmPnnAmeMalsoile ers:omslws SPmxal 20 I - Drys la.Dsardlm sk.Drvs alert OPstnd 51 L I 1 41 L- S. Assamenreakirroam.one Linarounamoo—Oposea)) ,. Rn,memnsnooe urloeomsmnn Gue, ameom-preiparoo mnimeos.2 Dust 1 S. resented Detention Pand (RR) c. ALD'A i R.k.EDxzl$eaal5) a. I memo. m consume s nrea, NB Soil, asa r.n Sheamamarom m conep inn xaa, " waz 1, azl on r. sheamon. m vgyaousd Xam v,mA 'a, n, m commAmemml Rlw,s on D o o D o Dm DDD DDD Do L.42 Ranl TOTAL IMPERNOUS COVERTREATEO (a[) O.UU AREACXECK: OK. TOT AL TURF AREA TREATEO(x) O.UU AREA CHECK: OK. TOTAL RUNOFF REDUCTION IN D.S. B(Nr) 0 TMAL PHOSPHORUS AVAILABLE FOR REMOVAL IN D.A. B (Ib/yrI 5.3a TOTAL PHOSPHORUS REMOVED WITH RUNOFF REDUCTION PRACTICES IN D.A. B (Ib/yrI O.O] TOTAL PHOSPHORUS REMAINING AMR APPLYING RUNOFF REDUCTION ACT TION PRICES IN O.A. B (Ib/y,)5.3a SEE WATER QUALITY COMPLIANCE TAR FOR SITE COMPLIANCE CALCUUIIIONS 10 h. wart Seele42 Dram xlll o D D D D ao L am am Dm 11. Filtering Practices (no ER) 12. Constructed Wnland (no RRI a. m n(lai 13A.wm pone al lmasar mull (spas - .t. m Pool 12111 xla) 15e, was Pone xz(cooml man)( spas xlal l.a. Manu/aauMT,eatmIML-es, Himossnamlt 1n.h.MI-motu,aliremer—Dies—rlM1ean6 .a'. an IoureeTmunam D--lemma TOTALIMPERNOUSCOVERTREATED(aU 2.3] AREACXECK: OR. TOTAL MANAGEDTURF AREATREMEO(ae) U.afi AREACXECK: ON. TOTAL PHOSPHORUS REMOVAL REQUIRED ON SITE(lb/yr( a.fl0 TOTAL PHOSPHORUS AVAILABLE FOR REMOVALIN D.A. B (Ib/yrI 5.3a TOTAL PHOSPHORUS REMOVED WITHOUT RUNOFF REDUCTION PRACTICES IN D.A. B (I ityrII 2.M TOTAL PHOSPHORUS REMOVED WITH RUNOFF REDUCTION PRACTICES IN D.A. B (I ityrII 0.w TOTAL PHOSPHORUS LOAD REDUCTION ACHIEVED IN D.A. B(IityrI 2.16 TOTAL PHOSPHORUS REMAINING AMR APPLYING BMP LOAD REDUCTIONS IN D.A. Blot, 3.21 SEE WATER QUALITY COMPLIANCE TAB FOR SITE COMPLIANCE CALCULATIONS NITROGEN REMOVED WITH RUNOFF REDUCTION PRACTICES IN DA. B (I ityI 0n0 NITROGEN REMOVED WITHOUT RUNOFF REDUCTION PRACTICES IN DA. B (Ib/y:I 0. TOTAL NTMOCENREMOVEOIN DA. B(Ib/yr( Ono 47 twPM Site Results (Water Quality Compliance) Area Checks D.A.A D.A.B D.A.0 D.A.D D.A.E AREAMECK FOREST/OPEN SPACE (at) 0.00 DOD 0.00 0.00 0.00 OR. IMPERVIOUS COVER(a[) IMPERVIOUS COVER TREATED )a[) 0J3 OJl 2.3] 2.3] 0.00 0.00 0.00 0.00 0.00 O.W OR.. OR.. MANAGEDTURF AREA (a[) 0.12 0.96 0.00 0.00 O.W OK. MANAGED TURF AREA TREATED (a[) 0.12 0.96 0.00 0.00 DOD OR.. AREA CHECK OK OR. OR. OK OR. Site Treatment Volume (ft')II 12,905 Runoff Reduction Volume and TP By Drainage Area D.A. A D.A. B D.A. C D.A. D D.A. E TOTAL RUNOFF REDUCION VOLUME ACHIEVED (na) 0 0 0 0 0 0 TP LOAD AVARABLE FOR REMOVAL Pb/yrI 1.59 5.3G 0.00 0.00 DOD 6.96 TPIDADREDUCTIONACHIEVED Pb/yrI 1.02 2.14 0.00 0.00 DOD 3.15 TP LOAD REMAINING IIb/yr) 0.57 3.21 0.00 0.00 O.W 3.]8 NnROGENLOADREDUCTIONACHIEVED Pb/yrI 0.00 0.00 0.00 0.00 DOD 0.00 Total Phosphorus FINAL POST -DEVELOPMENT TPLOAD Pb/yrI 9.11 TP LOAD REDUCTION REQUIRED IIb/yr) 4.80 TPIDAD REDUCTIONACHIEVED Pb/yrI 3.15 TP LOAD REMAINING (lb/,): 4.95 REMAINING TP LOAD REDUCTION REQUIRED Pb/yrI: 1.64 Total Nitrogen (For Information Purposes) POST-DEVELOPMEM IOAD IIb/NI 58.00 NnROGENLOAD REDUCTION ACHIEVED! yrI 0.00 RIMMING POST -DEVELOPMENT NRROSEN LOAD IIb/yr) 58.00 48 Virgmla Bunch Raduclion Mehra wor sneel DEQ Virginia Runoff Reduction Method Re -Development Compliance Spreadsheet - Version 3.0 BMP Design Specifications List 2013 Draft St&IS Specs Site Summary Project Title: ABC Block 1 Mass Grading- Major Amendment far Multifamily Data 44536 Total Rainhll(in): 43 Total DisZ dAcreage: 5.40 Site land Cover Summary Pre-ReDevelopment land Cover (acres) Asails BSoils CSoils DBoils Totals %of Trstal Forest/Open (acres) 0.00 0.00 0.00 0.00 0.00 0 Managed To,(,- 1 0.00 4.50 0.00 0.00 4.50 83 Impervious Cover(acres) 1 0.00 0.90 1 0.00 0.00 0.90 17 5.40 100 Port-ReDevelopment land Cover (acres( Asoils BSoils CSoils DSails Totals %af Total rest/Open(amaa mo 0.00 0.00 0.00 0.00 0 Managed To, (acres) 000 2.10 0.00 0.00 2.10 39 Impervious Cover (acres) 000 3.30 0.00 0.00 3.30 61 5.40 100 Site Tv and Land Cover Nutrient Loads Final Post -Development Post Post- Adjusted Pre- (PoM-ReDevelopment ReDevelopment Development ReDevelopment &Newlmpervious) (New Impervious) Site Rv 0.66 0.43 OAS 0.43 Treatment Volume)ft°) 12,905 4,628 8,276 4,628 TP Load (lb/,) 8.11 2.91 5.20 2.91 Total TP Load Reduction Required (Ib/yr) 4.80 0.58 4.22 Final Past -Development Load (Past-ReDevelopment&New Impervious) Pre- ReDevelopment TN Load (lb/yr) 58.00 28.63 pre- Final Post -Development Post-ReDevelopment TP ReDevelopment TP Load per ac re Load per acre Tp Load per acre (lb/acre/yr) (Ib/acre/vr) Ib acre 0.97 1.50 0.97 ---------------------------------------------------------------------------------------------------------------------------------------------------- Site Compliance Summary Maximum% Reduction Required Below 10% Pre-ReDevelopment oatl Total Runoff Volume Reduction(fe) 0 Total TP Load Reduction Achieved (Ib/ST) 3.15 Total IN Load Reduction Achieved(lb/yr) 0.00 Remaining Part Development TP Load (lb/yr) 495 Remaining TP Load Reduction (lb/yr) 1.64 Required ---------------------------------------------------------------------------------------------------------------------------------------------------- Drainage Area Summary DA.A DA.B DAC DAD D.A.E Total Forest/Open (a.) 0.00 0.O0 0.O0 0.00 0.00 0.00 Managed Turf (acres) 0.12 OAG 0.O0 0.00 0.00 0.58 Impervious Caver(acres) 0.71 2.37 0.O0 0.00 0.00 3.08 Total Area (acres) 0.83 2.83 0.00 0.00 0.00 3.66 Drainage Area Compliance Summary D.A. A D.A. B DA C DAD D.A. E Total TP Load Reduced Olh/yr) 1.02 2.14 moo 0.00 1 0,00 3.15 TN Load Reduced (Ib/yr) 0.00 0.00 moo 0,00 1 0,00 0.00 49 Summary Pdnl virgmia RWpn RadWion Melnotl woA5ne n Drainage Area A Summary Land Cover Summary ASoils BSoils CSoils DSoils Total %af Total Farest/Open(acres) 0.00 0.00 0.00 0.00 0.00 0 Managed Turf (acres) 1 0.00 0.12 0.00 0.00 0.12 14 Impervious Cover(acres) 1 0.00 0.71 0.00 0.00 0.71 86 0.83 BMP Selections Managed Turf Impervious Cover BMP Treatment TP Wad from UntreatedTP TP Removed TP Remaining Downstream Treatment Practice Credit Credit Area Volume (ks) Upstream to Practice Qbz) e(lbs) (Ib/yr) Qb/yr) to be Employed (acres) s) (acres) practices Qbs) 19.a. ManufacturedTreatment 0.71 2,535.56 0.00 1.59 0.64 0.95 14.b. WO - Filtering H0.12 area 14.b. Manufactured! Treatment Device - Filtering 1 2,535.56 0.95 0.00 0.38 0.57 Total Impervious Cover Treated (acres) 0.71 Total Turf Area Treated (acres) 0.12 Total TP Load Reduction Achieved in D.A. 1.02 (lb/yr) Total TN Wad Reduction Achieved in D.A. 0.00 Ib r Drainage Area B Summary Land Cover Summary ASoilz BSoils CSoils DSoils Total %af Total Forezt/Open(acres) 0.00 0.. 0.00 0.. 0.00 0 Managed Turf (acres) 0.00 0.46 0.00 0.00 0.46 16 Impervious Coaer(acrez) 0.00 1 2.37 1 0.00 1 0.00 2.37 84 2 83 BMP Selections Managed Turf Impervious Carer TP Wad from BMp Treatment Untreated TP Load TP Removed TP Remaining Downstream Treatment Practice CreditArea I Credit Area Volume (ks) Upstream to Practice (Ibz) (Ib/yr) (Ib/yr) to be Employed (acres) (acres) Practices Ibs Manufactured Treatment Device - I14.1s. 1 0.46 2.37 8,506.91 0.00 5.34 2.14 3.20 Fine Total Impervious Cover Treated(acres) 2.37 Total Turf Area Treated (acres) 0.46 Total TP Load Reduction Achieved in D.A. (lb/,) 2.14 Total TN Wad Reduction Achieved in D.A. (lb/w) 0.00 50 Summary Pont Independent Reports: Excerpt from NRCS Soils Report NOAA Precipitation Report 51 Hydrologic Soil Group —Albemarle County, Virginia 0 iJ 3 010'N - -- — ]1]60 ]i M 717370 M410 7174 7174 71MD 3 c MaP SOIe:1:1,870fpiilod onABrx�pe(11"x8.5")sleet. K N Me0.�s 0 75 a7 ,00 i9) AFixt e�� 30D Map prolecbm: Web Mercator Carvrcoordinates: WGS84 Edge Ohs: U1M Zone 17N WG584 Natural Resources Web Soil Survey Conservation Service National Cooperative Soil Survey g 3B°0'2T'N N 1 a U1 N MOW 3 M 11/3/2092 Page 1 of 4 MAPLEGEND Area of Interest (A01) 0 Area of Interest AOI) Solis Soil Rating Polygons 0 A Q AID o B Q BID o C 0 CID 0 D 0 Not rated or not available Soil Rating Lines . r A ,y AID rV B ram/ B/D N C N CID i D . . Not rated or not available Soil Rating Points A Q AID O B 0 BID Hydrologic Soil Group —Albemarle County, Virginia 0 C CID D 13 Not rated or not available Water Features Streams and Canals Transportation µ� Rails N Interstate Highways �y US Routes Major Roads Local Roads Background . Aerial Photography MAP INFORMATION The soil surveys that comprise your AOI were mapped at 1:15,800. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Albemarle County, Virginia Survey Area Data: Version 15, Sep 13, 2021 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Oct 14, 201 "ct 15, 2019 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. USDA Natural Resources Web Soil Survey 11/32093 Conservation Service National Cooperative Soil Survey Page 2 of Hydrologic Soil Group —Albemarle County, Virginia Hydrologic Soil Group Map unit symbol Map unit name Rating Acres in AOI Percent of AOI 27B Elioak loam, 2 to 7 percent slopes B 4.1 61.4% 27D Elioak loam, 15 to 25 percent slopes B 1.2 17.6% 34B Glenelg loam, 2 to 7 percent slopes B 0.1 1.8% 39D Hazel loam, 15 to 25 percent slopes B 1.3 19.3% Totals for Area of Interest 6.7 100.0% Description Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long -duration storms. The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B/D, and C/D). The groups are defined as follows: Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink -swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes. Natural Resources Web Soil Survey 11/3/2021 Conservation Service National Cooperative Soil Survey Page 3 of 4 Hydrologic Soil Group —Albemarle County, Virginia Rating Options Aggregation Method: Dominant Condition Component Percent Cutoff.- None Specified Tie -break Rule: Higher Natural Resources Web Soil Survey 11/3/2021 Conservation Service National Cooperative Soil Survey Page 4 of 4 55 10/27/2020 Precipitation Frequency Data Server NOAA Atlas 14, Volume 2, Version 3 Location name: Charlottesville, Virginia, USA* Sei* " Latitude: 38.00730, Longitude:-78.51760 Elevation: 429.65 ft** * source: ESRI Maps'a M n ✓ *'source: USGS POINT PRECIPITATION FREQUENCY ESTIMATES G.M. Bonnin, D. Martin, B. Lin, T. Parzybok, M.Yekta, and D. Riley NOAA, National Weather Service, Silver Spring, Maryland PF tabular I PF gra hD ical I Maps & aerials PF tabular PDS-based point precipitation frequency estimates with 90% confidence intervals (in inl Average recurrence interval (years) Duration 000 10 25 50 100 200I 500 0.352 0.419 0.491 0.552 0.622 0.675 0.725 0.772 0.828 5-min (0.317-0.391) (0.378-0.466) (0.442-0.5") (0.496-0.611) (0.556-0.686) (0.601-0.745) (0.642-0.799) (0.679-0.851) (0.721-0.915 0.563 0.670 0.786 0.883 0.991 1.08 1.15 1.22 1.31 10-min (0.506-0.625) (0.605-0.744) (0.708-0.872) (0.793-0.978) (0.886-1.09) (0.957-1.19) 1 (1.02-1.27) 1 (1.08-1.35) 1 (1.14-1.45) 0.703 0.842 0.995 1.12 1.26 1.36 1.46 1.54 1. 55 15-min (0.633-0.781) (0.760-0.936) (0.895-1.10) 1 (1.00-1.24) 1 (1.12-1.39) 1 (1.21-1.50) 1 (1.29-1.61) 1 (1.36-1.70) 1 (1.44-1.82) 0.964 1.16 1.41 1.62 1.86 2.05 2.23 2.40 2. 22 30-min (0.868-1.07) 1 (1.05-1.29) 1 (1.27-1.57) 1 (1.45-1.79) 1 (1.66-2.05) 1 (1.83-2.26) 1 (1.98-2.46) 1 (2.12-2.65) 1 (2.28-2.90) 1.20 1.46 1.81 2.11 2.48 2.78 3.07 3.37 3.76 60-min (1.08-1.34) 1 (1.32-1.62) 1 (1.63-2.01) 1 (1.89-2.33) 1 (2.21-2.73) 1 (2.47-3.06) 1 (2.72-3.39) 1 (2.97-3.72) 1 (3.28-4.16) 1.44 1.75 2.19 2.57 3.06 3.47 3.89 4.32 4.92 2-hr (127-1.65) 1 (1.53-2.00) 1 (1.92-2.49) 1 (2.26-2.92) 1 (2.67-3.47) 1 (3.01-3.93) 1 (3.35-4.40) 1 (3.70-4.89) 1 (4.16-5.57) 1.58 1.91 2.39 2.81 3.34 3.80 4.26 4.74 5.40 3-hr (1.38-1.82) 1 (1.67-2.20) 1 (2.09-2.75) 1 (2.44-3.22) 1 (2.90-3.83) 1 (3.27-4.33) 1 (3.65-4.86) 1 (4.03-5.41) 1 (4.53-6.17) 2.02 2.44 3.03 3.57 4.29 4.92 5.57 6.28 7.29 6-hr (1.79-2.29) 1 (2.15-2.76) 1 (2.67-3.43) 1 (3.13-4.03) 1 (3.74-4.84) 1 (4.25-5.53) 1 (4.78-6.27) 1 (5.33-7.07) 1 (6.09-8.21) 2.55 3.07 3.83 4.53 5.52 6.39 7.33 8.37 9. 00 12-hr E� (2.25-2.92) 1 (2.71-3.52) 1 (3.36-4.38) 1 (3.97-5.18) 1 (4.79-6.27) 1 (5.50-7.25) 1 (6.23-8.32) 1 (7.02-9.48) 1 (8.14-11.2) 3.05 3.69 4.72 5.58 6.85 7.95 9.16 10.5 12.5 24-hr (2.74-3.42) 1 (3.32-4.14) 1 (4.23-5.28) 1 (4.98-6.22) 1 (6.08-7.62) 1 (7.00-8.82) 1 (8.00-10.1) 1 (9.07-11.6) 1 (10.6-13.8) 3.59 4.36 5.54 6.52 7.94 9.12 10.4 11.8 13.9 2-day (3.22-4.01) 1 (3.91-4.87) 1 (5.82-7.26) 1 (7.03-8.82) 1 (8.03-10.1) 1 (9.09-11.6) 1 (10.2-13.1) 1 (11.8-15.5) 3.83 4.64 5.89 6.93 8.42 9.68 11.0 12.5 14.7 3-day (3.48-4.23) 1 (4.21-5.13) 1 (5.34-6.52) 1 (6.26-7.65) 1 (7.57-9.29) 1 (8.64-10.7) 1 (9.78-12.2) 1 (11.0-13.8) 1 (12.7-16.2) 4.06 4.92 6.24 7.33 8.91 10.2 11.7 13.2 15.5 4-day (3.73-4.45) (4.51-5.39) (5.72-6.85) (6.70-8.03) (8.11-9.75) (9.26-11.2) (10.5-12.8) (11.8-14.5) (13.6-17.0) 4.72 5.68 7.10 8.26 9.94 11.3 12.8 14.4 16.8 7-day (4.34-5.13) (5.23-6.18) (6.53-7.72) (7.58-8.99) (9.07-10.8) (10.3-12.3) (11.6-13.9) (12.9-15.7) (14.8-18.3) 5.34 6.41 7.92 9.14 10.9 12.3 13.8 15.3 17.6 10-day 11 (4.94-5.77) 1 (5.94-6.93) 1 (7.32-8.55) 1 (8.44-9.86) 1 (9.98-11.7) 1 (11.2-13.2) 1 (12.5-14.9) (13.8-16.6) (15.7-19.1) 7.02 8.37 10.1 11.5 13.3 14.8 16.3 17.8 19.9 20-day (6.58-7.50) 1 (7.85-8.94) 1 (9.47-10.8) 1 (10.7-12.3) 1 (12.4-14.2) 1 (13.7-15.8) 1 (15.1-17.4) (16.4-19.1) (18.2-21.4) 8.61 10.2 12.1 13.5 15.3 16.8 18.1 19.5 21.3 30-day (8.11-9.15) (9.62-10.8) (11.4-12.8) (12.7-14.3) (14.4-16.3) (15.7-17.8) (16.9-19.3) (18.1-20.7) (19.7-22.7) hftps://hdsc.rms.noas.govlhdscfpfdslpfds_printpage.html?lat=38.0073&Ion=-78.5176&data=depth&units=english&series=pds 1/5 10/27/2020 Precipitation Frequency Data Server 45-dayF 10.7 12.7 14.8 16.4 18.5 20.0 21.5 22.9 24.7 (10.2-11.4) (12.0-13.4) (14.0-15.7) (15.5-17.4) (17.4-19.6) (18.8-21.2) (20.2-22.8) (21.4-24.3) (23.0-26.3) 60-day12.6 14.8 17.1 18.8 21.0 22.6 24.2 25.6 27.5 (12.0-13.3) (14.1-15.6) (16.2-18.1) (17.8-19.9) (19.9-22.1) (21.3-23.8) (22.7-25.5) (24.1-27.1) (25.7-29.1) Precipitation frequency (PF) estimates in this table are based on frequency analysis of partial duration series (PDS). umbers in parenthesis are PF estimates at lower and upper bounds of the 90% confidence interval. The probability that precipitation frequency given duration and average recurrence interval) will be greater than the upper bound (or less than the lower bound) is 5%. Estimates at upper iecked against probable maximum precipitation (PIMP) estimates and may be higher than currently valid PMP values. PF graphical 57 hftps://hdsc.nws.noaa.govlhdsc/pfdslpfds_printpage.html?lat=38.0073&Ion=-78.5176&data=depth&units=english&series=pds 2/5 10/27/2020 Precipitation Frequency Data Server PDS-based depth -duration -frequency WDF) curves Latitude: 38.00730, Longitude:-78.51760 30 25 ..... : ..... : ................. -------------------- ................................ A c C C C C C >. >. >% >. >% >T >T >. A L L L L L M -o M M -o rp -o M M -0 M -o M M v v v v O U1 O N N r%1 4 n O O o t+1 IA Duration ~ N V 30 25 C L 20 a v 0 15 ,y d9 'a C-, 10 iv a 1 2 5 10 25 50 100 200 500 1000 Average recurrence interval (years) NOAA Atlas 14, Volume 2, Version 3 Created (GMT): Tue Oct 27 15:27:04 2020 Back to Top Maps & aerials Small scale terrain 58 hftps://hdsc.rms.noaa.gov/hdsctpfds/pfds_printpage.html?lat=38.0073&Ion=-78.5176&data=depth&units=english&series=pds 3/5 10/27/2020 Precipitation Frequency Data Server rry IF jfiilil� M � � P5 0- -'Charlottesville M° f/ CA ' I DUDLEY MOUNTAIN I 3km 2mi I�IEJi Large scale terrain w Washington, D.C.' , Han isonburq . AffWl%,— i Staunton L vlr,6INIA i Rich "T • rg A N orfol Large scale map 59 hftps://hdsc.rms.noaa.gov/hdsctpfds/pfds_printpage.html?lat=38.0073&Ion=-78.5176&data=depth&units=english&series=pds 4/5 10/27/2020 Precipitation Frequency Data Server An 0 0 W n ton rirginia / Harrisonburg _ -_ - Staunton I 21+{ I ' Virginia ch No rLynchburg Blacksburg oRoanoke r 100km NorN 60mi Backto Top US Department of Commerce National Oceanic and Atmospheric Administration National Weather Service National Water Center 1325 East West Highway Silver Spring, MD 20910 Questions?: HDSC.Questions@noaa.gov Disclaimer 60 hftps://hdsc.rms.noaa.gov/hdsctpfds/pfds_rrintpage.html?lat=38.0073&Ion=-78.5176&data=depth&units=english&series=pds 5/5