Press Alt + R to read the document text or Alt + P to download or print.

No preview available

The URL can be used to link to this page

Home My WebLink AboutSDP202100001 Calculations 2021-11-29Ivy Proper ALBEMARLE COUNTY, VIRGINIA DESIGN CALCULATIONS & NARRATIVE DECEMBER 30, 2020 REVISED: MARCH 19, 2021 REVISED: JUNE 249 2021 REVISED: SEPTEMBER 14, 2021 REVISED: NOVEMBER 29, 2021 �00000 0 • TIMMONS GROUP YOUR VISION ACHIEVED THROUGH OURS. Prepared by: Clint Shifflett, PE Timmons Group 608 Preston Avenue, Suite 200 Charlottesville, VA 22903 434.327.1690 CLINT W. Z: S FFLET >� Lie. N $ 4380 tea: 11/29/2021 IW-NON eL OG `�, Table of Contents Section Title 1. Project Narrative 2. LD-204 Inlet Calculations 3. LD-229 Pipe Calculations 4. LD-347 Hydraulic Grade Line Analysis 5. LD-269 Existing Culvert Adequacy Analysis 6. Pre and Post Developed HydroCAD Calculations 7. Virginia Runoff Reduction Method Worksheet Summary 8. Nutrient Credit Availability Letter 9. Clean Water Diversion Calculations Project Narrative: This project includes the construction of a new commercial building and parking lot with associated utilities and landscaping. The limits of disturbance is 0.79 acres. Water Ouality: The site is being treated as New Development. In the proposed condition there will be 0.07 acres of forest, 0.41 acres of turf, and 0.55 acres of impervious cover. Per the Virginia Runoff Reduction Redevelopment Spreadsheet, this will require that 0.96 lbs/yr of phosphorous be removed. Credits shall be purchased from a DEQ-Approved Nutrient Credit Bank in Accordance with VA code 62.1-44.15:35. Water Ouantity The site drains to an existing pipe under Ivy Road. A 54" CMP storage system is being proposed to detain the increase in flow. The CMP storage system detains the post - developed 1-year storm to meet the energy balance equation, and reduces the post - developed 10-year 24-hour storm to be less than the pre -developed 10-year 24-hour storm. FORM LD 204 STORMWATER INLET COMPUTATIONS SHEET 1 OF 2 ROUTE PROJECT Ivy Proper DESIGNER: KF CHECKED: DATE 6/8/2021 UNITS:NGLISH ---®--- 111• � 11 � 11 11 11 11 1: � 111 � 11: � 11�: 111 �� . 111 ® 111 11 1111 �--__-- ---_--- 1 1 • ��O- 1 1 11 1 1 1 : ® 111 ® 1 1 : � 11 � : -®-----------__-® INLETSOFT BY ENSOFTEC DATE: 6/8/2021 FORM LD 204 STORMWATER INLET COMPUTATIONS SHEET 2 OF 2 ROUTE PROJECT Ivy Proper DESIGNER: KF CHECKED: DATE 6/8/2021 UNITS:NGLISH INLET F. Q p Sag Inlets Only z0 2G SE O S� S " 3^ gym, _ of =, ou x F V u u u au u F 3 wFf `3 a r., i5 cox J a u v o r iF � a u�uU r� $� z= RO. v Z y6 V 0• .r ,= LCY 0F 0 5 885 0 0 Ahead/Rt 1.407 0.0100 2000 2 1 407 3.482 1> 80 ft Ex. 100 DI-1 2.000 0.200 0.90 0.18 Back/Lt. 0.000'RIGFY 0.170 0.25 0.0425 Back/Lt. 0.223 4.929 1.099 0 Back/Lt. 0 1 4.929 1 0 1 0 Ahead/Rt. 1.099 0.0100 2000. 2 1.099 2.953 1 Weir Flow INLETSOFT BY ENSOFTEC DATE: 6/8/2021 LD-229 STORM SEWER DESIGN COMPUTATIONS STORM FREQUENCY 10 PROJECT: LOCATION: COUNTY: Ivy Proper Free Union Designed by: KF Checked by: UNITS ENGLISH PIPE FROM POINT TO POINT DRAIN. AREA "A" Acre (3) RUNOFF COEER "C"MENT (4) CA INLET TIME Minutes (7) RAIN FALL In/Hr (8) RUNOFF INVERT ELEVATIONS LENGTH of Pipe Ft. (12) SLOPE Ft./Ft. (13) SIZE (Dia. Or Span/Rise) In. (14) SHAPE Number of Pipes Capacity CFS (15) Friction Slope Ft./Ft. NORMAL FLOW FLOW TIME REMARKS (18) INCRE- (5) ACCUM- ULATED (6) Late7Tota)ISQ CF UPPER END (10) LOWER END (11) Depth of Flow, do Ft. Area of Flow, An SgFt Hrn Ft. Vn Ft/Sec (16) En Ft. INCRE- MENT Minutes (17) ACC11M11NO. -LATER Minutes (17) REFERENCE (1) STA. REFERENCE (2) STA. 101 102 Ex. 100 0.01 0.90 0.01 0.25 5.18 5.83 0.00 16.89 512.50 511.70 80.33 0.00996 24 Circular 1 24.46 0.00490 1.22 2.01 0.56 8.40 2.32 0.16 5.34 103 104 102 0.00 0.00 0.24 5.07 5.86 0.00 16.84 512.88 512.50 50.34 0.00755 24 Circular 1 21.30 0.00490 1.34 2.24 0.58 7.52 2.22 0.11 5.18 105 SWM A 104 0.00 0.00 0.00 5.00 0.00 0.00 15.45 513.00 512.95 6.80 0.00735 24 Circular 1 21.01 0.00410 1.28 2.11 0.57 7.31 2.11 0.02 5.02 107 108 1106 0.08 0.74 0.06 1.37 5.15 5.84 0.00 8.08 514.53 513.67 57.42 0.01498 18 Circular 1 13.93 0.00530 0.82 0.99 0.40 8.17 1.86 0.12 5.27 109 110 108 0.07 0.71 0.05 1.31 5.04 5.87 0.00 7.73 515.41 514.63 52.25 0.01493 18 Circular 1 13.91 0.00480 0.80 0.96 0.39 8.08 1.81 0.11 5.15 111 112 110 3.37 0.38 1.26 1.26 5.00 5.89 0.00 7.44 515.81 515.51 19.87 0.01510 18 Circular 1 13.98 0.00450 0.78 0.93 0.38 8.04 1.78 0.04 5.04 113 114 SWMA 0.20 0.63 0.13 0.13 5.00 1 5.89 1 0.00 0.74 515.30 514.29 50.71 0.01992 15 Circular 1 9.88 0.00010 0.23 0.16 0.14 4.74 0.58 0.18 5.18 115 116 104 0.49 0.49 0.24 0.24 5.00 5.89 0.00 1.41 513.25 513.06 19.04 0.00998 15 Circular 1 6.99 0.00040 0.38 0.32 0.22 4.46 0.69 0.07 5.07 LD-347 PROJECT: Ivy Proper DESIGNED BY: KF HYDRAULIC GRADE LINE ANALYSIS Checked: CS INCIDENCE PROBABILITY 10 Year INLET OR JUNCTION STA. INVERT EL. OUTFLOW PIPE DEPTH OF FLOW OUTFLOW PIPE OUTLET WATER SURFACE ELEV. DIA. PIPE Do (In/mm) DESIGN DISCH. Do (CFS/CMS) LENGTH PIPE Lo (FtlM) FRICTION SLOPE, Sfo (FT/FT) (M/M) FRICTION LOSS Hf (FVM) JUNCTION LOSS SURFACE FLOW Adj. Ht 1.3 Ht (FllM) Inlet Shaping? YIN 0.5 Ht (Ft/M) FINAL H (FllM) Inlet Water Surface Elevation Top of MH Top of Inlet Elev. APPROX. Adjustment? Vo Contr. Ho (FtlM) Vi V'2/2g Hi (Expo) 0.35'MAX. (Vi2/2g) SKEW Angle K Bend H (FtlM) Sum HL (Ft/M) 1 2) 3 4 5 6 7) 8 9 10 11 12) (13 14 15 16) 16 17 18 19 106 1 513.670 108 513.670 1.50 514.870 18 8.078 57.42 0.00527 0.302 8.173 0.259 8.078 1.013 0.355 0.0 0.00 0.000 0.614 0.345 0.614 YES 0.307 0.609 515.479 522.050 O.K. 110 514.630 1.50 515.830 18 7.733 52.25 0.00483 0.252 8.078 0.253 8.036 1.003 0.351 0.0 0.00 0.000 0.604 0.294 0.604 YES 0.302 0.554 516.384 521.740 O.K. 112 515.510 1.50 516.710 18 7.439 19.87 0.00447 0.089 8.036 0.251 0.000 0.000 0.000 0.0 0.00 0.000 0.251 7.439 0.326 YES 0.163 0.252 516.962 520.500 O.K. LD-347 PROJECT: Ivy Proper DESIGNED BY: KF HYDRAULIC GRADE LINE ANALYSIS Checked: CS INCIDENCE PROBABILITY 10 Year INLET OR JUNCTION STA INVERT EL. OUTFLOW PIPE DEPTH OF FLOW OUTFLOW PIPE OUTLET WATER SURFACE ELEV. DIA. PIPE Do INmm DESIGN DISCH. Do CFS/CMS) LENGTH PIPE Lo (FVM FRICTION SLOPE, Sfo (FT/FT) M/M FRICTION LOSS Hf FUM JUNCTION LOSS SURFACE FLOW Adj. Ht 1.3 Ht FUM) Inlet Shaping? Y/N 0.5 Ht FUM FINAL H FUM Inlet Water Surface Elevation Top of MH Top of Inlet Elev. APPROX. Adjustment? VO Cont'. Ho FVM) Vi Vi'2/2g Hi (Expo) 0.35'MAX. 2/2) SKEW Angle K Bend H (FUM) Sum HL (FUM) 1 2 3 4 5 6 7 8 9 10 (11) 12 (13) (14) 15 16 16 17 18 19 SWM A 514.290 114 514.290 1.25 515.290 15 0.742 50.71 0.00012 0.006 4.736 0.087 0.000 0.000 0.000 0.0 0.00 0.000 0.087 0.742 0.113 YES 0.057 0.063 515.532 519.830 O.K. PROi Ivy Proper I SHEET UNITS OF ENGLISH CULVERT DESIGNER: REVIEWER: DESIGN KF CS FORM LD-269 DATE: 3/9/2021 DATE: ROAD COUNTY Albemarle (Zone 1) CULVERT Ec Clvrt. VA NOAA Shition Free Union HYDROLOGICAL DATA Method: RATIONAL Domingo Aim 4.81 Acres Time ofConcen6alion 5 Minutes DESIGN FLOWS SMdr. EISF- Eli= L= S= SKEW= Elev_D ELHWd= 51356 51160 R SILO ft 4987 ft 106Ya 00 Roadway Width 30 R ROADWAY ft ft _ _______________________________________________ Her I ______ ___________________ DEPRESSION 0 ..n"Bed 0013 ELEVATION Stream Bed __________ 516.00 a _________________________ El, Road L.,1h 100 Freeboard= ShW Ekv. Rt=—ft H TWDEPTH TW TW VEL Chamml low El _ Sl07 A SoPce Type PAVED XVALUEI R L08 ft 322 fps 511.07 R R,L(yeam) FLOW (COO 10 Design 1157 2 Check 9.70 25 Max. 1576 CULVERT DESCRIPTION: TYPE: Single/Multiple Conforming Inlet Edge Dwriptioo: Square edge w/heedwnll TOTAL FLOW U c6 FLOWRM BARREL ON c@ HEADWATER CALCULATIONS CONTROL HEADWATER ELEV ft OUTLET VEL fps MOiIMUM SHOULDER ELEV. R COMMENTS INLET CONTROL OUTLET CONTROL Sin a/Multi le Condemnor/Broken Beek C.I eM H`Vm HWi ft FALL It ELHWi It TW a do ft (d Dy2 ft M a ke H a ELHWo R M)tTERIAI. SHAPE Sim (in) N Mi.ngs n CMPMedC,. CircWm 24 1 003 11.57 11,6 0,98 1.83 000 51343 L08 122 161 161 0.50 0.88 513.56 513.56 407 970 97 0.92 L63 000 51323 L98 1.11 1,56 1,56 0.50 062 51324 51324 402 1576 15A 140 228 0.00 513,88 126 143 1,72 1,72 0.50 162 51441 51441 502 Broke. Back Cldvert TAILWATER DATA: TAILWATER RESULTS: ROADWAY DATA: ROADWAY OVERTOPPING: LENGTH Elev. SKEW° Lncl Shape Tncceeha - 0.035 Dischor,,e efs aim. ft Flow depih it Velocdy fps Shearforce PSF eadway WMdSft 30 D.W, c6 0—pp-8 Dkcharge Cf5 Oveeeppng Ekvadon ft 3i,..WMlb,a Side Slope Lb (H:1V) Side Slope RL(H:1V) Channel Slope. RlR 2.00 eiriffine Type PAVED 1.50 DeW - 512.15 108 322 0,67 rop of Road Elevator, 0 518 si 0 000 1.00 Clxck 51205 0.98 3.07 0,61 -englb of Road, If 100 heck 0 ON 0.0100 51233 126 3.49 0,79 0 ON Dismnce levadon TECHNICAL FOOTNOTES: (1) USEQ/NBFORBOXCULVERTS (4) ELhi=HWi+ ELi(INVERT OF INLET CONTROL SECTION) (6)he-7W or(do + W)(WHICHEVER IS GREATER) (2)HWi/D= HW/D OR HWi/D FROM DESIGN CHARTS (5)TW BASED ON DOWNSTREAM CONTROL OR FLOW (7)H=[I+ke+(29n2L/R13'V/2g (3) FALL =HWI-(ELHWd-ELst); FALL IS ZERO FOR CULVERTS ON GRADE DEPTH IN CHANNEL SUBSCRIPT DEFENTOONS: COMMENTS / DISCUSSION: CULVERT BARREL SELECTED HWd DESIGN HEADWATER i INLET SIZE: n Hwi HW IN INLET CONTROL 0 OUTLET SHAPE: MATERIAL: HWo HW IN OUTLET CONTROL sf Smoothed ENTRANCE: @ culvert face CULVERTSOFT by ENSOFTEC, INC. ERO3EL17 Ivy Proper I CULVERT DESIGN FORM LD-269 ROAD COUNTY Albemarle (Zone 1) SHEEF OF DESIGNER: u DATE: 3/9n021 CULVERT ExClvrt. VA UNITS ENGF iCD REVIEWER: CS DATE: WA \ Station I'rec Un,on H.W. ELEV VIS DISCHARGE 014.o 514.4 - 514.2 - >514.0 W &13.8 +>513.6 x 513.4 513.2 - 513.0 0 2 4 6 8 10 12 14 16 18 DISCHARGE OUTLET VELOCITY VIS DISCHARGE 6.0 5.0 4.0 0.0 1 1 1 1 0 2 4 6 8 10 12 14 16 18 DISCHARGE TW DEPTH VIS DISCHARGE IA TW VELOCITY VIS DISCHARGE 12 3.6 3.5 3.5 3.4 1.0 y 0.8 3.4 tl - o 3.3 3-2 -_ 2 0.6 F 0.4 > 2 32 32 3.1 0.2 1 3.1 - 0.0 0 2 4 6 8 10 12 14 16 18 DISCHARGE 3.0 0 2 4 6 8 10 12 14 16 18 DISCHARGE CULVERTSOFf by ENSOFfEC, INC. 1S 2S Pre Developed ite Pre Developed ON Site PRE S4 Reach X 4on Llnk 4S 5S Post Offsite uted ost ON Site Routed 6P (new ond) 8S i %$ �ted Post Off Site Un P st ON Site Unrouted 9L (new Link) Ivy Proper Pre -Post 54in Prepared by Timmons Group Printed 11/8/2021 HydroCAD® 10.10-4a s/n 08663 ©2020 HydroCAD Software Solutions LLC Page e Area Listing (all nodes) Area CN Description (acres) (subcatchment-numbers) 3.400 61 >75% Grass cover, Good, HSG B (1S, 2S, 4S, 5S, 7S, 8S) 2.880 98 Paved parking, HSG B (1S, 2S, 4S, 5S, 7S, 8S) 3.360 60 Woods, Fair, HSG B (1S, 2S, 4S, 8S) 9.640 72 TOTAL AREA Ivy Proper Pre -Post 54in Prepared by Timmons Group Printed 11/8/2021 HydroCAD® 10.10-4a s/n 08663 ©2020 HydroCAD Software Solutions LLC Page Soil Listing (all nodes) Area Soil Subcatchment (acres) Group Numbers 0.000 HSG A 9.640 HSG B 1S, 2S, 4S, 5S, 7S, 8S 0.000 HSG C 0.000 HSG D 0.000 Other 9.640 TOTAL AREA Ivy Proper Pre-Post_54in Prepared by Timmons Group Printed 11/8/2021 Ground Covers (all nodes) HSG-A HSG-B HSG-C HSG-D Other Total Ground Subcatchment (acres) (acres) (acres) (acres) (acres) (acres) Cover Numbers 0.000 3.400 0.000 0.000 0.000 3.400 >75% Grass cover, Good 1 S, 2S, 4S, 5S, 7S, 8S 0.000 2.880 0.000 0.000 0.000 2.880 Paved parking 1S, 2S, 4S, 5S, 7S, 8S 0.000 3.360 0.000 0.000 0.000 3.360 Woods, Fair 1S, 2S, 4S, 8S 0.000 9.640 0.000 0.000 0.000 9.640 TOTAL AREA Ivy Proper Pre-Post_54in Type 1124-hr 1Year Rainfall=3.01" Prepared by Timmons Group Printed 11/8/2021 HydroCAD® 10.10-4a s/n 08663 ©2020 HydroCAD Software Solutions LLC Paoe 5 Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1 S: Pre Developed Offsite Runoff Area=3.860 ac 25.91% Impervious Runoff Depth>0.63" Flow Length=740' Tc=20.1 min CN=70 Runoff=2.68 cfs 0.204 of Subcatchment2S: Pre Developed ON Site Runoff Area=0.970 ac 34.02% Impervious Runoff Depth>0.77" Tc=6.0 min CN=73 Runoff=1.43 cfs 0.063 of Subcatchment4S: Post Offsite Routed Runoff Area=3.380 ac 21.89% Impervious Runoff Depth>0.59" Flow Length=740' Tc=20.1 min CN=69 Runoff=2.15 cfs 0.167 of Subcatchment5S: Post ON Site Routed Runoff Area=0.650 ac 70.77% Impervious Runoff Depth>1.62" Tc=6.0 min CN=87 Runoff=1.94 cfs 0.088 of Subcatchment7S: Post ON Site Unrouted Runoff Area=0.310 ac 29.03% Impervious Runoff Depth>0.73" Tc=6.0 min CN=72 Runoff=0.43 cfs 0.019 of Subcatchment8S: Post Off Site Unrouted Runoff Area=0.470 ac 55.32% Impervious Runoff Depth>1.21" Tc=6.0 min CN=81 Runoff=1.08 cfs 0.047 of Pond 6P: (new Pond) Peak Elev=514.71' Storage=0.023 of Inflow=2.87 cfs 0.255 of Outflow=2.50 cfs 0.254 of Link 3L: PRE Inflow=3.01 cfs 0.267 of Primary=3.01 cfs 0.267 of Link 9L: (new Link) Inflow=2.97 cfs 0.320 of Primary=2.97 cfs 0.320 of Total Runoff Area = 9.640 ac Runoff Volume = 0.588 of Average Runoff Depth = 0.73" 70.12% Pervious = 6.760 ac 29.88% Impervious = 2.880 ac Ivy Proper Pre-Post_54in Type 1124-hr 1Year Rainfall=3.01" Prepared by Timmons Group Printed 11/8/2021 HydroCAD® 10.10-4a s/n 08663 @ 2020 HydroCAD Software Solutions LLC Page 6 Summary for Subcatchment 1S: Pre Developed Offsite Runoff = 2.68 cfs @ 12.15 hrs, Volume= 0.204 af, Depth> 0.63" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 1Year Rainfall=3.01" Area (ac) CN Description 1.390 60 Woods, Fair, HSG B 1.470 61 >75% Grass cover, Good, HSG B 1.000 98 Paved parking, HSG B 3.860 70 Weighted Average 2.860 74.09% Pervious Area 1.000 25.91 % Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.3 100 0.0150 0.16 Sheet Flow, Grass: Short n= 0.150 P2= 3.65" 8.4 500 0.0200 0.99 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 1.4 100 0.0600 1.22 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 0.0 40 0.0312 16.54 51.95 Pipe Channel, 24.0" Round Area= 3.1 sf Perim= 6.3' r= 0.50' n= 0.010 PVC. smooth interior 20.1 740 Total Ivy Proper Pre -Post 54in Type 11 24-hr 1 Year Rainfall=3.01 " Preaared by Timmons Group Printed 11/8/2021 3 1 Subcatchment 1S: Pre Developed Offsite Hydrograph 2.68 GIs Type Il 24-hr Wear Rainfall T3.01" ---Runoff Arecl=1860-6c- Ru"off', Volume=0.'204', of Runoff DepthP-0.63" Flow Lehgttth=740' -C Time (hours) I ❑ Runoff Ivy Proper Pre-Post_54in Type 1124-hr 1Year Rainfall=3.01" Prepared by Timmons Group Printed 11/8/2021 HydroCAD® 10.10-4a s/n 08663 @ 2020 HydroCAD Software Solutions LLC Page 8 Summary for Subcatchment 2S: Pre Developed ON Site Runoff = 1.43 cfs @ 11.98 hrs, Volume= 0.063 af, Depth> 0.77" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 1Year Rainfall=3.01" Area (ac) CN Description 0.580 60 Woods, Fair, HSG B 0.060 61 >75% Grass cover, Good, HSG B 0.330 98 Paved parking, HSG B 0.970 73 Weighted Average 0.640 65.98% Pervious Area 0.330 34.02% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment 2S: Pre Developed ON Site Hydrograph 1.43 cfs ❑ Runof Type 0 24-hr 1Year Rainfall-3.01" Runoff Area=0.970 ac Runoff Volume=0.',063 of Runoff Depth?0.77r T'c=610 min (,N=73 11 12 13 14 15 16 17 18 19 Time (hours) Ivy Proper Pre-Post_54in Type 1124-hr 1Year Rainfall=3.01" Prepared by Timmons Group Printed 11/8/2021 HydroCAD® 10.10-4a s/n 08663 @ 2020 HydroCAD Software Solutions LLC Page 9 Summary for Subcatchment 4S: Post Offsite Routed Runoff = 2.15 cfs @ 12.16 hrs, Volume= 0.167 af, Depth> 0.59" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 1Year Rainfall=3.01" Area (ac) CN Description 1.250 60 Woods, Fair, HSG B 1.390 61 >75% Grass cover, Good, HSG B 0.740 98 Paved parking, HSG B 3.380 69 Weighted Average 2.640 78.11 % Pervious Area 0.740 21.89% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.3 100 0.0150 0.16 Sheet Flow, Grass: Short n= 0.150 P2= 3.65" 8.4 500 0.0200 0.99 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 1.4 100 0.0600 1.22 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 0.0 40 0.0312 16.54 51.95 Pipe Channel, 24.0" Round Area= 3.1 sf Perim= 6.3' r= 0.50' n= 0.010 PVC. smooth interior 20.1 740 Total Ivy Pre -Post 54in Type 1124-hr 1Year Rainfall=3.01" Timmons Group Printed 11/8/2021 Subcatchment 4S: Post Offsite Routed Time (hours) i i i ■Runoff --- }Tye@a� 24�hF Wear kainfallT3.01" Runbff Areci=3.380 i3c Ru Ooff', Vo l u mip=0.',167', of Runoff Depth;o0.69" ---Ptow-LEhgth=74W- Tc=20,1 Min dN=,69 5 Ivy Proper Pre-Post_54in Type 1124-hr 1Year Rainfall=3.01" Prepared by Timmons Group Printed 11/8/2021 HydroCAD® 10.10-4a s/n 08663 @ 2020 HydroCAD Software Solutions LLC Page 11 Summary for Subcatchment 5S: Post ON Site Routed Runoff = 1.94 cfs @ 11.97 hrs, Volume= 0.088 af, Depth> 1.62" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 1Year Rainfall=3.01" Area (ac) CN Description 0.000 60 Woods, Fair, HSG B 0.190 61 >75% Grass cover, Good, HSG B 0.460 98 Paved parking, HSG B 0.650 87 Weighted Average 0.190 29.23% Pervious Area 0.460 70.77% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment 5S: Post ON Site Routed Hydrograph 2 1.94 cfs Type 0 24-hr 1Year Rainfall-3.01" Runoff Area=0.650 ac Runoff Volume=0.',088 of Runoff Depth?1.62" T'c=610 min (,N=87 10 11 12 13 14 15 16 17 18 19 Time (hours) ❑ Runaff Ivy Proper Pre-Post_54in Type 1124-hr 1Year Rainfall=3.01" Prepared by Timmons Group Printed 11/8/2021 HydroCAD® 10.10-4a s/n 08663 @ 2020 HydroCAD Software Solutions LLC Page 12 Summary for Subcatchment 7S: Post ON Site Unrouted Runoff = 0.43 cfs @ 11.98 hrs, Volume= 0.019 af, Depth> 0.73" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 1Year Rainfall=3.01" Area (ac) CN Description 0.000 60 Woods, Fair, HSG B 0.220 61 >75% Grass cover, Good, HSG B 0.090 98 Paved parking, HSG B 0.310 72 Weighted Average 0.220 70.97% Pervious Area 0.090 29.03% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment 7S: Post ON Site Unrouted Hydrograph 0.46 r 0.44 -� --------'-------L____�_ � V.ry 0.42 - �I 0.38 - __L_ 0.34 I 0.32 --- J----L- -L----L---J----L- _ 0.28 --- - ---'i-------'i---J----� - e 0.2fi_L _J _L 0 0.22 -__J____L___J____L___J____L_ LL 0.2 -J I 0.16 _J 0.14 - -� 0.12 0.1 I I I I I I 0.06 - -_ JI I ____ L___J____L___J____L_ I I I I L I J I J -- ''I-TypeA-24thu 9-Y9ar-RairrfaHT3:0 "- iZun6ff Are & 31 a iae- Rudoff VoKffM--9:�t9_e -r-- Runoff Delpth:�0-33"_ - _L___J____ Tt;=_fs1_flMin__ __ r___ J____ r___r____ r___ N� ef0_ _I _ I _L___ i____L _1 L _r _y _r _I _r _i _r I I I II -r-------r--------r--------r- I 11 12 13 14 15 16 17 18 19 20 Time (hove) ■ Runoff Ivy Proper Pre-Post_54in Type 1124-hr 1Year Rainfall=3.01" Prepared by Timmons Group Printed 11/8/2021 HydroCAD® 10.10-4a s/n 08663 @ 2020 HydroCAD Software Solutions LLC Page 13 Summary for Subcatchment 8S: Post Off Site Unrouted Runoff = 1.08 cfs @ 11.98 hrs, Volume= 0.047 af, Depth> 1.21" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 1Year Rainfall=3.01" Area (ac) CN Description 0.140 60 Woods, Fair, HSG B 0.070 61 >75% Grass cover, Good, HSG B 0.260 98 Paved parking, HSG B 0.470 81 Weighted Average 0.210 44.68% Pervious Area 0.260 55.32% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment 8S: Post Off Site Unrouted Hydrograph 1.08 cfs ❑Runoff Type 0 24-hr 1Year Rainfall-3.01" Runoff Area=0.470 ac Runoff Volume=0.',047 of Runoff Depth?1.21" T'c=610 min (,N=81 10 11 12 13 14 15 16 17 18 19 Time (hours) Ivy Proper Pre-Post_54in Type 11 24-hr 1Year Rainfall=3.01" Prepared by Timmons Group Printed 11/8/2021 HydroCAD@ 10.10-4a s/n 08663 @ 2020 HydroCAD Software Solutions LLC Page 14 Summary for Pond 6P: (new Pond) Inflow Area = 4.030 ac, 29.78% Impervious, Inflow Depth > 0.76" for 1Year event Inflow = 2.87 cfs @ 12.01 hrs, Volume= 0.255 of Outflow = 2.50 cfs @ 12.16 hrs, Volume= 0.254 af, Atten= 13%, Lag= 9.0 min Primary = 2.50 cfs @ 12.16 hrs, Volume= 0.254 of Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 514.71' @ 12.16 hrs Surf.Area= 0.018 ac Storage= 0.023 of Plug -Flow detention time= 6.1 min calculated for 0.254 of (100% of inflow) Center -of -Mass det. time= 4.9 min ( 820.4 - 815.5 ) Volume Invert Avail.Storage Storage Description #1 513.00' 0.066 of 54.0" Round Pipe Storage L= 180.0' Device Routing Invert Outlet Devices #1 Primary 513.00' 7.5" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #2 Primary 514.40' 16.0" W x 8.0" H Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Primary 516.91' 3.0' long Sharp -Crested Rectangular Weir 2 End Contraction(s) Primary OutFlow Max=2.49 cfs @ 12.16 hrs HW=514.71' (Free Discharge) 11=Orifice/Grate (Orifice Controls 1.75 cfs @ 5.69 fps) 2=Orifice/Grate (Orifice Controls 0.74 cfs @ 1.79 fps) 3=S ha rp-C rested Rectangular Weir( Controls 0.00 cfs) Pond 6P: (new Pond) Hydrograph I I I I I 2.50 cfs I I I I I I I I I I I I I I I I I I I I I I I I Z I I I I I I I I I I I I I I I I I I V 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 I I I I I I I I Time (hours) ❑ Inflow ❑ Primary Inflow Area=4.030 ac Peak Elev=514.71' Storage=0.023 of I I I I I I 17 18 19 Ivy Proper Pre -Post 54in Type 1124-hr 1Year Rainfall=3.01" Prepared by Timmons GrouD Printed 11/8/2021 w Pond 6P: (new Pond) Stage -Discharge Discharge (cfs) Pond 6P: (new Pond) Stage -Area -Storage Storage (acre -feel) ■ Primary ■ Storage Ivy Proper Pre-Post_54in Type 1124-hr 1Year Rainfall=3.01" Prepared by Timmons Group Printed 11/8/2021 HydroCAD® 10.10-4a s/n 08663 @ 2020 HydroCAD Software Solutions LLC Page 16 Summary for Link 3L: PRE Inflow Area = 4.830 ac, 27.54% Impervious, Inflow Depth > 0.66" for 1Year event Inflow = 3.01 cfs @ 12.13 hrs, Volume= 0.267 of Primary = 3.01 cfs @ 12.13 hrs, Volume= 0.267 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs I I I I I I I I I I I I I �. ____r___-____� I I I I I 3.( 3 I I I I I I I I I I I I I I I I I I I I 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 -Y -F -Y I I I I I I 2 I I I I I I I I I I I I I I I I 3 I I I I I I 0 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 I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I Link 3L: PRE ■ r I____r___1____ ■ Primary I nflpw Area=14.8$0 ac I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I 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 ►/O91�0iMM000V/ZO0RZFOiMM/�� 1 11 12 13 14 15 16 17 18 19 20 Ivy Proper Pre-Post_54in Prepared by Timmons Group Type 11 24-hr 1 Year Rainfall=3.01 " Printed 11/8/2021 Summary for Link 9L: (new Link) Inflow Area = 4.810 ac, 32.22% Impervious, Inflow Depth > 0.80" for 1Year event Inflow = 2.97 cfs @ 12.03 hrs, Volume= 0.320 of Primary = 2.97 cfs @ 12.03 hrs, Volume= 0.320 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Link 9L: (new Link) ❑ Inflow ❑ Primary 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Ivy Proper Pre-Post_54in Prepared by Timmons Group Type 11 24-hr 10Year Rainfall= 5.50 " Printed 11/8/2021 Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1 S: Pre Developed Offsite Runoff Area=3.860 ac 25.91% Impervious Runoff Depth>2.20" Flow Length=740' Tc=20.1 min CN=70 Runoff=10.16 cfs 0.707 of Subcatchment2S: Pre Developed ON Site Runoff Area=0.970 ac 34.02% Impervious Runoff Depth>2.46" Tc=6.0 min CN=73 Runoff=4.48 cfs 0.199 of Subcatchment4S: Post Offsite Routed Runoff Area=3.380 ac 21.89% Impervious Runoff Depth>2.11" Flow Length=740' Tc=20.1 min CN=69 Runoff=8.55 cfs 0.596 of Subcatchment5S: Post ON Site Routed Runoff Area=0.650 ac 70.77% Impervious Runoff Depth>3.78" Tc=6.0 min CN=87 Runoff=4.31 cfs 0.205 of Subcatchment7S: Post ON Site Unrouted Runoff Area=0.310 ac 29.03% Impervious Runoff Depth>2.38" Tc=6.0 min CN=72 Runoff=1.38 cfs 0.061 of Subcatchment8S: Post Off Site Unrouted Runoff Area=0.470 ac 55.32% Impervious Runoff Depth>3.19" Tc=6.0 min CN=81 Runoff=2.73 cfs 0.125 of Pond 6P: (new Pond) Peak Elev=516.91' Storage=0.061 of Inflow=9.66 cfs 0.801 of Outflow=9.12 cfs 0.799 of Link 3L: PRE Inflow=11.34 cfs 0.906 of Primary=11.34 cfs 0.906 of Link 9L: (new Link) Inflow=11.18 cfs 0.985 of Primary=11.18 cfs 0.985 of Total Runoff Area = 9.640 ac Runoff Volume = 1.893 of Average Runoff Depth = 2.36" 70.12% Pervious = 6.760 ac 29.88% Impervious = 2.880 ac Ivy Proper Pre-Post_54in Type 1124-hr 10 Year Rainfall= 5.50 " Prepared by Timmons Group Printed 11/8/2021 HydroCAD® 10.10-4a s/n 08663 @ 2020 HydroCAD Software Solutions LLC Page 19 Summary for Subcatchment 1S: Pre Developed Offsite Runoff = 10.16 cfs @ 12.14 hrs, Volume= 0.707 af, Depth> 2.20" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10Year Rainfall=5.50" Area (ac) CN Description 1.390 60 Woods, Fair, HSG B 1.470 61 >75% Grass cover, Good, HSG B 1.000 98 Paved parking, HSG B 3.860 70 Weighted Average 2.860 74.09% Pervious Area 1.000 25.91 % Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.3 100 0.0150 0.16 Sheet Flow, Grass: Short n= 0.150 P2= 3.65" 8.4 500 0.0200 0.99 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 1.4 100 0.0600 1.22 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 0.0 40 0.0312 16.54 51.95 Pipe Channel, 24.0" Round Area= 3.1 sf Perim= 6.3' r= 0.50' n= 0.010 PVC. smooth interior 20.1 740 Total Ivy Proper Pre -Post 54in Type 1124-hr Wear Rainfall=5.50" Prepared by Timmons Group Printed 11/8/2021 Subcatchment 1S: Pre Developed Offsite 11 i i i i i it it i i i i i ___ � RunoH 10.16 cfs ----- ---- -- --------------------------- 10 1 1 Type II 2&hr s i OYear I�airifaIIr5.90" ___J _1 J _1 _L _J___--- I____1____L--- J---- L___I---- 1____ e ' Rtunbff Areal=3.860 i3c Runoff Vo1um7=0I707?af Runoff )6p 2.20,E 3 -- - - M 5 ibw Lehgth=740� ----;--- ----T&20',T-rain I N- 11T 1 2 1 12 13 Time (hours) Ivy Proper Pre-Post_54in Type 1124-hr 10 Year Rainfall= 5.50 " Prepared by Timmons Group Printed 11/8/2021 HydroCAD® 10.10-4a s/n 08663 @ 2020 HydroCAD Software Solutions LLC Page 21 Summary for Subcatchment 2S: Pre Developed ON Site Runoff = 4.48 cfs @ 11.97 hrs, Volume= 0.199 af, Depth> 2.46" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10Year Rainfall=5.50" Area (ac) CN Description 0.580 60 Woods, Fair, HSG B 0.060 61 >75% Grass cover, Good, HSG B 0.330 98 Paved parking, HSG B 0.970 73 Weighted Average 0.640 65.98% Pervious Area 0.330 34.02% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment 2S: Pre Developed ON Site Hydrograph 5- 4.48 cfs ❑ zunof Type 0 24-hr 4 10Year Rainfall-5.50" Runoff Area=0.970 ac 3. Runoff Volume=0.199 of Runoff Depth?2.46" ,T'c=6,0 min 2 trN=';73 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Ivy Proper Pre-Post_54in Type 1124-hr 10 Year Rainfall= 5.50 " Prepared by Timmons Group Printed 11/8/2021 HydroCAD® 10.10-4a s/n 08663 @ 2020 HydroCAD Software Solutions LLC Page 22 Summary for Subcatchment 4S: Post Offsite Routed Runoff = 8.55 cfs @ 12.14 hrs, Volume= 0.596 af, Depth> 2.11" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10Year Rainfall=5.50" Area (ac) CN Description 1.250 60 Woods, Fair, HSG B 1.390 61 >75% Grass cover, Good, HSG B 0.740 98 Paved parking, HSG B 3.380 69 Weighted Average 2.640 78.11 % Pervious Area 0.740 21.89% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.3 100 0.0150 0.16 Sheet Flow, Grass: Short n= 0.150 P2= 3.65" 8.4 500 0.0200 0.99 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 1.4 100 0.0600 1.22 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 0.0 40 0.0312 16.54 51.95 Pipe Channel, 24.0" Round Area= 3.1 sf Perim= 6.3' r= 0.50' n= 0.010 PVC. smooth interior 20.1 740 Total Ivy Type/1 24-hr 10Year Rainfall=5.50" Timmons Group Printed 11/8/2021 Subcatchment 4S: Post Offsite Routed 8 _---`--------`--------'- I .55cfs cfs I I I I I I I I I I I I I I I _J _L 6 ... 5 I I I I I 3 LL I I I I j I I I I I I I I I I I 3 ___ I____I__-I____I____I__ I I I I I I I I I I I I 2 I I Time (hours) I I I I I I I ____`_----i----'----'----�--- ■Runoff Type11 2"r 10Yea r _lka i nfaU r 5.9.0" _ I I I I I I I Runbff Areal=3.380 i3c ' Ruooff', Vol',ump=0.',596'1 of --_ Runof( Depth�2-.14" I I I I I I I - - - IHow-Lehgtth--740-' Tc=2( rI-M it-,N=169 Ivy Proper Pre-Post_54in Type 1124-hr 10 Year Rainfall= 5.50 " Prepared by Timmons Group Printed 11/8/2021 HydroCAD® 10.10-4a s/n 08663 @ 2020 HydroCAD Software Solutions LLC Page 24 Summary for Subcatchment 5S: Post ON Site Routed Runoff = 4.31 cfs @ 11.97 hrs, Volume= 0.205 af, Depth> 3.78" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10Year Rainfall=5.50" Area (ac) CN Description 0.000 60 Woods, Fair, HSG B 0.190 61 >75% Grass cover, Good, HSG B 0.460 98 Paved parking, HSG B 0.650 87 Weighted Average 0.190 29.23% Pervious Area 0.460 70.77% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment 5S: Post ON Site Routed Hydrograph 4.31 cfs ❑ zunof Type I� 24-hr- 4 10Year RainfallT5.50" Runoff Area=0.650 ac 3 Runoff Volume=0.',205 of Runoff Depth?3.78" Tc=610 min 0=87 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Ivy Proper Pre-Post_54in Type 1124-hr 10 Year Rainfall= 5.50 " Prepared by Timmons Group Printed 11/8/2021 HydroCAD® 10.10-4a s/n 08663 @ 2020 HydroCAD Software Solutions LLC Page 25 Summary for Subcatchment 7S: Post ON Site Unrouted Runoff = 1.38 cfs @ 11.97 hrs, Volume= 0.061 af, Depth> 2.38" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10Year Rainfall=5.50" Area (ac) CN Description 0.000 60 Woods, Fair, HSG B 0.220 61 >75% Grass cover, Good, HSG B 0.090 98 Paved parking, HSG B 0.310 72 Weighted Average 0.220 70.97% Pervious Area 0.090 29.03% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment 7S: Post ON Site Unrouted Hydrograph 1.38 cfs Type 0 24-hr 0Year Rainfall-5.50" Runoff Area=0.310 ac 1 LRunoff Volume=0.',061 of Runoff DepM>2.38" T'c=610 min 0=72 10 11 12 13 14 15 16 17 18 19 20 Time (hours) ❑ Runoff Ivy Proper Pre-Post_54in Type 1124-hr 10 Year Rainfall= 5.50 " Prepared by Timmons Group Printed 11/8/2021 Runoff = Summary for Subcatchment 8S: Post Off Site Unrouted 2.73 cfs @ 11.97 hrs, Volume= 0.125 af, Depth> 3.19" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10Year Rainfall=5.50" Area (ac) CN Description 0.140 60 Woods, Fair, HSG B 0.070 61 >75% Grass cover, Good, HSG B 0.260 98 Paved parking, HSG B 0.470 81 Weighted Average 0.210 44.68% Pervious Area 0.260 55.32% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment 8S: Post Off Site Unrouted Hydrograph ❑ Runoff Type 11 24-hr 10Year Rainfall=5.50" Runoff Area=0.470 ac 2 Runoff Volume=0.125 of Runoff Depth>3.19" T'c=610 min �N=81 1 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Ivy Proper Pre-Post_54in Type 11 24-hr 10Year Rainfall= 5.50 " Prepared by Timmons Group Printed 11/8/2021 HydroCAD® 10.10-4a s/n 08663 @ 2020 HydroCAD Software Solutions LLC Page 27 Summary for Pond 6P: (new Pond) Inflow Area = 4.030 ac, 29.78% Impervious, Inflow Depth > 2.38" for 10Year event Inflow = 9.66 cfs @ 12.06 hrs, Volume= 0.801 of Outflow = 9.12 cfs @ 12.16 hrs, Volume= 0.799 af, Atten= 6%, Lag= 5.9 min Primary = 9.12 cfs @ 12.16 hrs, Volume= 0.799 of Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 516.91' @ 12.16 hrs Surf.Area= 0.013 ac Storage= 0.061 of Plug -Flow detention time= 5.3 min calculated for 0.799 of (100% of inflow) Center -of -Mass det. time= 4.4 min ( 799.4 - 795.0 ) Volume Invert Avail.Storage Storage Description #1 513.00' 0.066 of 54.0" Round Pipe Storage L= 180.0' Device Routing Invert Outlet Devices #1 Primary 513.00' 7.5" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #2 Primary 514.40' 16.0" W x 8.0" H Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Primary 516.91' 3.0' long Sharp -Crested Rectangular Weir 2 End Contraction(s) Primary OutFlow Max=9.08 cfs @ 12.16 hrs HW=516.90' (Free Discharge) 11=Orifice/Grate (Orifice Controls 2.80 cfs @ 9.11 fps) 2=Orifice/Grate (Orifice Controls 6.29 cfs @ 7.07 fps) 3=S ha rp-C rested Rectangular Weir( Controls 0.00 cfs) Pond 6P: (new Pond) Hydrograph ❑ Inflow 9.66 cfs ❑ Primary 10 9.12 cfs Inflow Area=4.030 ac 9 I U1 Peak Elev=516.91 8 .� 6 i ___I____i____rr___r 3 4 i 7____i ___T____i____i p 1 I� Time (hours) Storage=0.061 of Ivy Proper Pre -Post 54in Type // 24-hr Wear Rainfall=5.50" Prepared by Timmons GrouD Printed 11/8/2021 w Pond 6P: (new Pond) Stage -Discharge Discharge (cfs) Pond 6P: (new Pond) Stage -Area -Storage Storage (acre -feel) ■ Primary ■ Storage Ivy Proper Pre-Post_54in Type 1124-hr 10 Year Rainfall= 5.50 " Prepared by Timmons Group Printed 11/8/2021 HydroCAD® 10.10-4a s/n 08663 @ 2020 HydroCAD Software Solutions LLC Page 29 Summary for Link 3L: PRE Inflow Area = 4.830 ac, 27.54% Impervious, Inflow Depth > 2.25" for 10Year event Inflow = 11.34 cfs @ 12.08 hrs, Volume= 0.906 of Primary = 11.34 cfs @ 12.08 hrs, Volume= 0.906 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs 12 I I I T--- _I---- r___ T____r I I I I I I I I 10 ' I I 9 ' I I I ---------------- I I I I I I I I I 6 ___�-------- �'----- L 0 LL 5 4 I I I I 3 I I I I I I I I 2 i I I I I I I Link 3L: PRE I I I I I I I ____ ________ I____ T_______ ■Inflow ■ Primary 34 cfs I n�lpw?Area=4.$U 41c r--- ,---- r___ I I I I I I I I I I I ____1___J____L___J____L I I I I I ___ I I I I I I I I _L _J _L I I I I I I I I I I I I I I I I I I 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Ivy Proper Pre-Post_54in Type 1124-hr 10 Year Rainfall= 5.50 " Prepared by Timmons Group Printed 11/8/2021 HydroCAD® 10.10-4a s/n 08663 @ 2020 HydroCAD Software Solutions LLC Page 30 Summary for Link 9L: (new Link) Inflow Area = 4.810 ac, 32.22% Impervious, Inflow Depth > 2.46" for 10Year event Inflow = 11.18 cfs @ 12.01 hrs, Volume= 0.985 of Primary = 11.18 cfs @ 12.01 hrs, Volume= 0.985 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Link 9L: (new Link) ----- I-------L--- L - - - I I I 12 I I I I I 11.18 c I I I ,0 I I I ----I----i----'.-- I I I I I I I I I y� 7 I _J _I _1 _I _L _J V I I I I I 6 0 I I I I LL I I I I 4 I I I I I I 3 I I I z I I I L___ J____ L___ I I I I I I I ■ Inflow ■ Primary I Inflpw!Area=4.810c _ 1 1 _I _L _J _L I I I I I 1 _I _L _J _L I I I I I I 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 _L I I I I I I I I I I I I I I I I I I I I 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Virginia Runoff Reduction Method! Mrksheet DEq Virginia Runoff Reduction Method New Development Compliance Spreadsheet - Version 3.0 BMP Design Specifications List: 2013 Draft Stds & Specs Site Summary Project Title: Ivy Proper Date: 44449 Total Rainfall= 431nches Site Land Cover Summary A soils B Soils C Soils D Soils Totals %of Total Forest/Open (acres) 0.00 0.07 0.00 0.00 0.07 7 Managed Turf (acres) 1 0.00 0.41 0.00 0.00 0.41 40 Impervious Cover (acres) 1 0.00 0.55 0.00 0.00 0.55 53 1.03 100 Site Tv and Land Cover Nutrient Loads Site Rv 0.59 Treatment Volume ft 2,202 TP Load (lb/yr) 1.38 TN Load (lb/yr) 9.90 Total TP Load Reduction Required (lb/yr) 0.96 Site Compliance Summary Total Runoff Volume Reduction (ft) 0 Total TP Load Reduction Achieved (lb/yr) 0.00 Total TN Load Reduction Achieved (lb/yr) 0.00 Remaining Post Development TP Load 1.38 (lb/yr) Remaining TP Load Reduction (lb/yr) 0.96 Required ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ Drainage Area Summary D.A. A D.A. B DA. C D.A. D D.A. E Total Forest/Open (acres) 0.00 0.00 0.00 0.00 0.00 0.00 Managed Turf(acres) 0.00 0.00 0.00 0.00 0.00 0.00 Impervious Cover (acres) 0.00 0.00 0.00 0.00 0.00 0.00 Total Area (acres) 0.00 0.00 0.00 0.00 0.00 0.00 Drainage Area Compliance Summary DA. A D.A. B DA. C D.A. D DA. E Total TP Load Reduced (Ib/vr) 0.00 0.00 0.00 0.00 0.00 0.00 Summary Print Virginia Runoff Reduction Method Worhsheet TN Load Reduced (lb/yr) 1 0.00 1 0.00 1 0.00 1 0.00 1 0.00 1 0.00 Drainage Area A Summary Land Cover Summan A Soils BSoils CSOIIS DSoils Total %of Total Forest/Open (acres) 0.00 0.00 0.00 0.00 0.00 0 Managed Turf (acres) 1 0.00 1 0.00 0.00 0.00 0.00 0 Impervious Cover (acres) 1 0.00 1 0.00 0.00 0.00 0.00 0 0.00 BMP Selections Managed Turf Impervious BMP Treatment TP Load from Untreated TP Load TP Removed TP Remaining Downstream Practice Credit Area [over Credits I Volume (Tt ( Upstream to Practice (16s) (16/yr) (Ih/yr) Treatmentto be (acres) Area (acres) practices (Ihz) Employed Total Impervious Cover Treated (acres) 0.00 Total Turf Area Treated (acres) 0.00 Total TP Load Reduction Achieved in D.A. (lb/yr) 0.00 Total TN Load Reduction Achieved in D.A. (lb/yr) 0.00 Drainage Area B Summary Land Cover Summary A Soils BSoils CSoils DSolis Total %of Total Forest/Open (acres) 0.00 0.00 0.00 0.00 0.00 0 Managed Turf (acres) 1 0.00 1 0.00 0.00 0.00 0.00 0 Impervious Cover (acres) 1 0.00 1 0.00 0.00 0.00 0.00 0 0.00 BMP Selections Managed Turf Impervious BMPTreatment TP Load from Untreated TP Load TP Removed TP Remaining Downstream Practice Credit Area Cover Credit I z Volume (ft ( Upstream to Practice (16s) (16/yr) (Ih/yr) Treatmentto 6e (acres) Area (acres) practices (Ihz) Employed Total Impervious Cover Treated (acres) 0.00 Total Turf Area Treated (acres) 0.00 Total TP Load Reduction Achieved in D.A. (lb/yr) 0.00 Total TN Load Reduction Achieved in D.A. (lb/yr) 0.00 Summary Print Virginia Runoff Reduction Method Worhsheet Drainage Area C Summary Land Cover Summary A Soils BSolls CSolls DSolls Total %of Total Forest/Open (acres) 0.00 0.00 0.00 0.00 coo o Managed Turf (acres) 1 0.00 1 0.00 0.00 1 0.00 coo I o Impervious Cover (acres) 1 0.00 1 0.00 0.00 1 0.00 coo I o 0.00 BMP Selections Managed Turf Impervious BMP Treatment TP Load from Untreated TP Load TP Removed TP Remaining Downstream Practice Credit Area Cover Credit I Volume (fts ( Upstream to Practice (Ihs) (16/yr) (Ih/yr) Treatmentto 6e (acres) Area (acres) practices (Ihs) Employed Total Impervious Cover Treated (acres) 0.00 Total Turf Area Treated (acres) 0.00 Total TP Load Reduction Achieved in D.A. (lh/yr) 0.00 Total TN Load Reduction Achieved in D.A. (lh/yr) 0.00 Drainage Area D Summary Land Cover Summan A Soils B Soils C Soils D Soils Total %of Total Forest/Open (acres) 0.00 0.00 0.00 0.00 0.00 0 Managed Turf (acres) 1 0.00 1 0.00 0.00 1 0.00 0.00 1 0 Impervious Cover (acres) 1 0.00 1 0.00 0.00 1 0.00 0.00 1 0 0.00 BMP Selections Managed Turf Impervious BMP Treatment TP Load from Untreated TP Load TP Removed TP Remaining Downstream Practice Credit Area Cover Credit I Volume (fts) Upstream to Practice (Ihs) (16/yr) (Ih/yr) Treatmentto 6e (acres) Area (acres) practices (Ihs) Employed Total Impervious Cover Treated (acres) 0.00 Total Turf Area Treated (acres) 0.00 Total TP Load Reduction Achieved in D.A. (lh/yr) 0.00 Total TN Load Reduction Achieved in D.A. (lh/yr) 0.00 Drainage Area E Summary Summary Print Virginia Runoff Reduction Method VVorksheet Land Cover Summary A Soils BSoils CSolls DSo0s Total %of Total Forest/Open (acres) 0.00 0.00 0.00 0.00 0.00 0 Managed Turf (acres) 1 0.00 1 0.00 0.00 1 0.00 0.00 1 0 Impervious Cover (acres) 1 0.00 1 0.00 0.00 1 0.00 0.00 1 0 0.00 BMP Selections Managed Turf Impervious BMP Treatment TP Load from Untreated TP Load TP Removed TP Remaining Downstream Practice Credit Area Cover Credit I a Volume (Tt) Upstream to Practice (Ihs) (16/yr) (Ih/yr) Tre6e (acres) Area (acres) practices (Ihz) EmployEmployedd Total Impervious Cover Treated (acres) 0.00 Total Turf Area Treated (acres) 0.00 Total TP Load Reduction Achieved in D.A. 0.00 (Ih/yr) Total TN Load Reduction Achieved in D.A. 0.00 (Ih/yr) Runoff Volume and CN Calculations 1-yearstorm 2-year storm 10-year storm Target Rainfall Event (in) I 0.00 0.00 0.00 Drainage Areas RV & CN Drainage Area A Drainage Area B Drainage Area C Drainage Area D Drainage Area E CN 0 0 0 0 0 RR (f?) 0 0 0 0 0 1-year return period RV wa RR (. -in) 0.00 0.00 0.00 0.00 0.00 RV w RR (wnln) 0.00 0.00 0.00 0.00 0.00 CN adjoined 0 0 0 0 0 2-year return period RV wo RR (.in) 0.00 0.00 0.00 0.00 0.00 RV w RR (wsin) 0.00 0.00 0.00 0.00 0.00 CN adjusted 0 0 0 0 0 10-year return period RVwa RR 0.00 0.00 Ow 0.00 0.00 -(--in) RR RV w (wsin) 0.00 0.00 0.00 0.00 0.00 CN adjusted 0 0 0 0 0 Summary Print ECOSYSTEM SERVICES, LLC 1739 Allied Street, Suite A Charlottesville, VA 22903 540.578.4296 www.ecosystemservices.us jongecosystemservices.us June 21, 2021 Kevin Flynn, PE Project Engineer Timmons Group 608 Preston Avenue, Suite 200 Charlottesville, VA 22903 RE: Nutrient Offset Credit — Credit Availability Letter Ivy Proper Project TMP: 058A2-00-00-01400 & 058A2-00-00-02000 Project HUC: 020802040402 Bank HUC: 020802040202 Bank Address: 1705 Lambs Road, Charlottesville, VA 22901 Dear Mr. Flynn, We appreciate the opportunity to provide a credit availability letter for 0.64 pounds of phosphorus for the above referenced project. This letter is to certify that as of today, June 21, 2021, Ivy Creek Nutrient Bank has 131.39 pounds of phosphorus (TP), 202.10 pounds of nitrogen (TN), and 41,432.12 pounds of TSS available for transfer to those entities requiring offsets in accordance with the Chesapeake Bay Watershed Nutrient Credit Exchange Program (VA Code § 62.1-44.19:14 et seq.). Those offsets are also transferable in accordance with the Virginia stormwater offset program (VA Code § 62.1-44.15:35) and the Virginia Soil and Water Conservation Board's Guidance Document on Stormwater Nonpoint Nutrient Offsets approved on July 23, 2009, to those regulated entities qualifying for nutrient credits. We can certainly accommodate your needs and could offer to fulfil the order of 0.64 pounds of phosphorus. Please feel free to contact us with any questions. I hope we have the opportunity to work together on this project. Sincerely, Ecosystem Services, LLC By: * ^ 1t. Jonathan R. Roller, AOSE PSS CNMP Manager —Authorized Representative Worksheet for CWD 2-Year Project Description Friction Method Manning Formula Solve For Normal Depth Input Data Roughness Coefficient 0.035 Channel Slope 0.050 ft/ft Left Side Slope 0.050 H:V Right Side Slope 0.667 H:V Discharge 3.59 cis Results Normal Depth 19.3 in Flow Area 0.9 ft2 Wetted Perimeter 3.5 ft Hydraulic Radius 3.1 in Top Width 1.15 ft Critical Depth 17.3 in Critical Slope 0.089 ft/ft Velocity 3.88 ft/s Velocity Head 0.23 ft Specific Energy 1.84 ft Froude Number 0.763 Flow Type Subcritical GVF Input Data Downstream Depth 0.0 in Length 0.0 ft Number Of Steps 0 GVF Output Data Upstream Depth 0.0 in Profile Description N/A Profile Headloss 0.00 ft Downstream Velocity Infinity ft/s Upstream Velocity Infinity ft/s Normal Depth 19.3 in Critical Depth 17.3 in Channel Slope 0.050 ft/ft Critical Slope 0.089 ft/ft Bentley Systems, Inc. Haestad Methods Solution FlowMasler Ivy Proper Exist Pipe Capacity1mri Center [10.03.00.03] 9/8/2021 27 Stemon Company Drive Suite 200 W Page 1 of 1 Watertown, CT 06795 USA +1-203-755-1666