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HomeMy WebLinkAboutWPO202200032 Calculations 2022-07-19Berkmar Self Storage COUNTY OF ALBEMARLE, VIRGINIA VSMP wro-2022—xxxxx DESIGN CALCULATIONS & NARRATIVE JULY 15, 2022 • TIMMONS GROUP YOUR VISION ACHIEVED THROUGH OURS. Prepared by: Jessica Denko, PE Timmons Group 608 Preston Ave, Suite 200 Charlottesville, VA 22903 434.327.5381 L JESW I. KWO Lk, No. 57291 07/15/22 Table of Contents Section Title Project Narrative 2 Pipe and Inlet Computations Virginia Runoff Reduction Method Worksheet Summary 4 Pre -Developed HydroCAD Calculations Post -Developed HydroCAD Calculations 6 Channel analysis 7 Nutrient Credit Availability Letter Project Narrative: This project includes the construction of a hotel, a mini storage facility, required parking lot, and associated utilities. Currently this site drains to the Keglers regional pond, which is located downhill to the south of the site, between the bowling alley and Lowes home improvement store. This pond will be used for stormwater quantity measurements. Pre - developed conditions were established from the survey performed by Roudabush, Gale and Associates in June 2022. Water Quality Compliance: The disturbed area of 4.57 ac was used for water quality analysis. In the proposed conditions there will be 1.77 acres of managed turf and 2.8 acres of impervious. The required phosphorus removal is 5.0 lb/yr which will be purchased from an offsite nutrient credit bank. Water Quantity Compliance: This project area currently drains to the offsite Kegler's detention basin. Utilitzing a combination of record drawings, survey data, and GIS, the current drainage area to the pond was determined for existing conditions. The pre developed drainage area for Lowes was determined utilizing the record drawings for Lowes and Keglers. The predeveloped drainage areas for Berkmar Overlook DA B and DA C were determined utilizing WP0201900050. The pre -developed drainage area for Kegler's was determined utilizing available GIS information. Onsite project area was determined with survey data. The pond was modeled in existing conditions updating to SCS 24-hr methodology. Onsite area for pre and post conditions was used in the energy balance equation to determine a required reduction in flow for the pond. The resulting 1-yr peak flow and volume numbers were used in the energy balance equation to determine a required reduction in flow for the pond outfall in the post -developed condition. The energy balance equation resulted in an allowable flow for the onsite area of 0.23 cfs. The target flow rate from the detention pond for the 1-yr storm, was determined by removing the pre -developed 1-yr peak flow rate for the onsite area and adding the allowable 1-yr peak flow rate for the post -developed condition. The post developed 2- and 10-yr peak flow rates are detained below pre developed flow rates. These values are in the table below. Energy Balance Equation for onsite //areas: QI YR POST-DEV ALLOW — IF m (Q1 YR PRE-DEV t RV, YR PRE-DEV)/RV, YR POST-DEV *All Q and RV values are from onsite only to determine Qiaiow. Applying QlAuow to the pond routing: QI YR POND ALLOW — Q1PRE-POND — Q1PRE-DEV ONS/TE + QIYR POST-DEVALLOW The channel from the Berkmar site outfall and the pond was analyzed to verify capacity which was found to be adequate. The total depth of the channel is a minimum of 2 ft and the 10-year depth was 0.9 ft. PEAK FLOW ANALYSIS DRAINAGE TOTAL Tc PEAK FLOW RATE RUNOFF AREA CN (CFS) VOLUME AREA NAME (AC) (MIN) 1 YR 10 YR (AC -FT) Pre Developed Onsite 4.34 16.7 62 1.40 8.87 0.124 Drainage Area Pre Developed Offsite 65.05 20.5 78 78.36 222.84 5.561 Drainage Area COMBINED PRE DEVELOPMENT FLOW AT OUTFALL 29.34 127.48 Post Developed Onsite 4.34 9.6 88 12.09 5.05 0.613 Drainage Area Post Developed Offsite 65.05 20.5 78 78.36 222.84 5.561 Drainage Area COMBINED POST DEVELOPMENT FLOW AT OUTFALL 21.63 123.76 OUTFALL CHANNEL PROTECTION AND FLOOD PROTECTION CALCULATIONS ENERGY POST FLOW BALANCE ALLOWED PER IMPROVEMENT ENERGY BALANCE* FACTOR (CFS) 0.800 78.59 CHANNEL PROTECTION (ENERGY BALANCE) - 1 YR FOR ONSITE AREAS QI YR POST-DEV ALLOW = IFS (QI YR PRE-DEV * RVI YR PRR-DEV)/RVI YR POST-DEV 0.800 ' ( 1.40 ' 0.124 ) / 0.613 = 0.23 CFS APPLYING Q1 YR PosT-DEV ALLOW TO THE POND ROUTING: QI YR POND ALLOW = Q1 YR PRE-DEV POND - Q1 YR PRE-DEV ONSITE + QI YR POST-DEV ALLOW 29.34 1.40 + 0.23 = 28.17 CFS 21.63 CFS 5 28.17 CFS FLOOD PROTECTION -10 YR Q10 YR POST-DEV POND 5 QIO YR PRE-DEV POND 123.76 CFS 9 127.48 CFS FORM LD 204 STORMWATER INLET COMPUTATIONS SHEET 1 OF 2 PROJECT Berkmar Self Storage DESIGNER: Rman Niekerk CHECKED: DATE 7/15/2022 UNITS:NGLISH INLET Z h W Z z¢ Q E 66 08 4' .� v� � '� � .� �' 3 iL 0.' �' y F" .v. �" F a >> O} � rq�ui2 66 5 Sag Inlets Only Y K m Z y F O a f✓ G %� u @i C 102 DI-3C 8.000 0.140 0.84 0.1176 Buk/LL 0.0001RIGHT 0.118 5.042 0.595 0.671 0.0721 0.0231 4.610 0.000 0 0.0231 1 2.00 Bwk/LL 0 5.042 0 0 Ahead/Rt. L266 0.0721 8 1.266 L571 0.185 0.500 0.37 3.571 5.668 Weir Flow 106 DI-1 4.000 0.730 0.42 0.3066 O'LEFT 0.307 5.042 1.548 0 1.548 0.0503 0.0503 3.895 2.000 0.5135 0.0208 0.4135 0.798 1.29 0.0000 0.0503 21.965 4.000 0.182 0.864 1.337 0 211 1.643 108 DI-3A 6.000 0.320 0.84 0.2688 O'LEFT 0.269 5.042 1.356 0 1.356 0.0709 0.0208 2.504 2.000 0.7987 0.0833 4.0048 0.998 3.50 0. 1458 0.1663 12.245 6.000 0A90 0.702 0.952 0.404 2.125 112 DI-3B 6.000 0.520 0.65 0.338 O'LEFT 0.338 5.042 1.704 0 1.704 0.0953 0.0208 5.221 2.000 0.3831 0.0208 1 0.725 2.00 0.0833 0.0812 22.649 6.000 0.265 0.425 0.725 0.979 1.303 114 DI-3C 12.000 0.750 0.75 0.5625 Bwk/LL 0.0001LEFT 0.563 5.042 2.839 0 0.0225 0.0208 8.284 2.000 0.2414 0.0208 1 2.00 Buk/Lt. 0 5.042 0 0 Ahead/Rt. 2.839 0.0225 12 2.839 2.210 0.250 0.500 0.5 4.210 8.853 Weir Flow 116 DI-1 1.250 0.010 0.64 0.0064 WRIGHT 0.006 5.042 0.03 0.056 0.086 0.0676 0.0208 2.489 0.000 0 0.0208 1 0.845 2.00 0.0833 0.0912 3.291 1.250 0.380 0.864 0.074 0.012 0.621 118 DI-1 1.000 0.050 0.59 0.0295 WRIGHT 0.03 5.042 0.151 0.015 0.166 0.0744 0.0208 3.127 0.000 0 0.0208 1 0.643 2.00 0.0833 0.0743 5.047 1.000 0.198 0.662 0.110 0.056 0.781 120 DI-1 2.000 0.210 0.50 0.105 WRIGHT 0.105 5.042 0.529 0 0.529 0.0160 0.0208 6.437 0.000 0 0.0208 1 0.630 2.00 0.0833 0.0733 5.224 2.000 0.383 0.748 0.396 0.133 1.607 122 DI-1 1.000 0.010 0.67 0.0067 WRIGHT 0.007 5.042 0.035 0.003 0.038 0.0475 0.0208 1.958 0.000 0 0.0208 1 0.852 2.00 0.0833 0.0918 2.093 1.000 0.478 0.871 0.033 0.005 0.489 124 DI-3B 6.000 0.360 0.87 0.3132 INLETSOFT BY ENSOFTEC DATE: 7/15/2022 FORM LD 204 STORMWATER INLET COMPUTATIONS SHEET 2 OF 2 PROJECT Berkmar Self Storage DESIGNER: Rman Niekerk CHECKED: DATE 7/15/2022 UNITS:NGLISH INLET Z O w x V za O a V a O " s w O x o c�u W V =c"iF 0v� F F of O q a a' ��vvF F� C 3 W F �f y ti $ m D,j o CCJ1 h� a '' $ O r�' �`.'-w �" >�f O yU O 2 a Sag Inlets Only < r rL m a F o o o o a x` L a pp aF i v O'RIGHT 0.313 5.042 1.578 0 L578 0.0163 0.0208 5.381 2,000 0.3717 0.0833 4.0048 0.860 3.50 0.1458 0,1462 9.071 6,000 0.661 0.858 1,353 0225 2.843 126 DI-3A 2.000 0. 100 0.90 0.09 Buk/Lt. 0.0001RIGHT 0.09 5.042 0.454 0 0.0200 0.0208 L790 2,000 1.1173 0.0833 4.0048 3.50 Buk/Lt, 0 5.042 0 0 Ahead/Rt. 0.454 0.0200 2 0.454 1.289 0.166 0.333 0.4985 3.289 5.163 Weir Flow 128 DI-3B 8.000 0260 0,90 0.234 WRIGHT 0,234 5.042 1.18 0.209 1.389 0.0640 0.0208 5.211 0.000 0 0.0208 1 0,725 2.00 0.0833 18,436 8.000 0.434 0.641 0.890 0.499 1.301 130 DI-3B 4.000 0.170 0.88 0.1496 d0.1647 WRIGHT 0.15 5.042 0.756 0.404 1.160 0.0363 0.0208 3.065 2.000 0.6525 0,0833 4.0048 0,987 3.50 0.1458 9.435 4.000 0.424 0.629 0.730 0.430 2.265 INLETSOFT BY ENSOFTEC DATE: 7/15/2022 BERKMAR STORM NETWORK STORM SEWER DESIGN COMPUTATIONS STORM FREQUENCY 10 PROJECT: LOCATION: COUNTY: Designed by: Checked by: UNITS ENGLISX PIPE NO FROM POINT TO POINT DRAM. AREA RUNOFF COEFF. C. (4) CA TOTAL INLET TIME Minutes (7) RAM FALL IN (8) RUNOFF Q us (9) INVERT ELEVATIONS LENGTH of Pipe Ft (12) SLOPE FtJFt (13) SIZE (Dia. Co SpanAh.) In. (14) SHAPE Cap oy CPS (15) FnMon SI ape F[IFt VEL V. PON. (16) FLOW TIME M. (17) REMARKS (19) INCRE-ACCUM- MINT (5) ELATED (6) ADDTL CA UPPER END (10) LOWER END (11) REFERENCE (1) STA. REFERENCE (2) STA_ "A' Acre (3) 119 120 15+0503 its 15+0168 0230 0450 O.IP1 Ono 0.126 8750 5526 1268 508701 5080,17 327M 0020 8NO CimWar 1850 0NO 57M 0095 .1 Rnnf4min 117 its 15+0168 116 14+ 1493 On50 0590 0030 0259 ONO I"S 5505 1426 507%7 507070 36754 0024 8NO CimWar 2021 On11 6291 0097 121 in 116 Onto OS70 0007 0.1% ONO 6ON 6230 0659 508507 507070 31 W3 0046 8NO Omuta 2817 0003 6598 0078 .1 Rnnf4fain 115 116 14+6493 108 14+5391 Onto 06W 0006 0.371 ONO 8.943 5483 2035 506967 502670 37638 0.114 8NO Omuta 4421 0024 12433 0050 109 Ito 15+6374 108 14+5371 0NO On00 0ON 4623 4623 72W 5.898 27266 510210 5M 555 HOOM 0088 24M Omuta M585 0012 21503 0085 i.1. WP0201900050 107 108 14+5371 130 13+2574 0320 08W 0269 5263 ONO 1993. 5472 28797 SW455 498596 127971 0015 24M Omuta 29536 0014 107" 0199 129 114 11+5131 130 11+2031 0750 0780 0.585 0.585 ONO 0ON 8901 5207 5011SO 5M 870 31008 0010 15 NO Omuta 69% 0006 6262 0093 113 130 13+25.74 104 12+05.76 0170 0880 0150 5997 ONO 6500 6.087 36503 4984% 493980 119975 0.038 24.M Omuta 47543 0On 16723 0120 105 Ion 12+0166 104 12+0576 0730 0420 0.307 0.307 ONO 0ON 8901 2.no 496.110 495 NO 24347 0042 ISM Omuta 23187 0001 8863 0016 103 104 12+0576 128 11+0601 0ON 0ON 0000 6.3M 0No 6620 6053 38.ISO 493877 492920 95951 0010 24M Omuta 24166 0024 12147 0132 127 128 11+06.01 102 10+2348 0260 0NO 0234 6.538 ONO 6751 6017 39341 492 no 488 M1 823P 0054 24M Omuta 57.139 0026 19653 0070 125 126 13+1942 112 12+5853 0100 0NO 0ON 0ON ONO 0NO 8901 0.801 497637 490.150 W.8% 0.123 ISM Omuta 24.531 0No 9192 0110 Ht 112 13+2574 102 10+2357 0520 06W 0.333 0689 0266 8250 5600 3.885 490.050 488753 258.827 0005 ISM Omuta 4.953 0003 4478 0963 =1 Rnnf&.. 101 102 10+2348 IN 10M851 0.1W 0.8W 0.118 7.560 0216 9213 5425 41011 488241 4%092 14969 0.1" 24M CimWar 92.US 0028 28698 ONO ml. Rnnf&.. BERKMAR STORM NETWORK PROJECT: DESIGNED BY: HYDRAULIC GRADE LINE ANALYSIS Checked: INCIDENCE PROBABILITY 10 Y68F INLET OR JUNCTION INLET STATION OUTLET WATER SURFACE EIEV. DIA PIPE Do (In) DESIGN DISCH. Go (CFS) LENGTH PIPE LO (ED FRICTION SLOPE, St (FT/m FRICTION LOSS Hf (ED JUNCTION LOSS FINAL H (Ft) Ioet Wake su a B.H. RM Eke Coom Vo Ho (Ft) OI N OM M-2a, HI M* HA HI IS HI SE HI 102 10+23.57 487.69 24 41.01 14.97 2.80% 0.42 28.7 3.2 39.34 19.65 ]]3.16 6 2.1 53.99 3 8.29 0 TRUE 4.57 492.26 494 OK -1.74 128 11+06.01 492.26 24 39.34 $2.38 2.58% 2.12 19.65 1.5 38.16 12.15 463.52 2.29 0.8 8.2 0.3 2.6 0 TRUE 3.42 495.68 498.66 OK -2.98 104 12+05.76 495.68 24 38.16 95.95 2.42% 2.33 12.15 0.57 36.5 16.72 610.43 4.34 1.52 84.54 2.87 4.96 0 TRUE 4.81 500.49 500.94 OK -0.46 130 11+20.31 500.49 24 36.5 119.97 2.22% 2.66 16.72 1.09 28.8 10.74 309.39 1.79 0.63 88.93 1.25 2.97 0 TRUE 4.15 504.63 506.3 OK -1.67 108 14+53.71 504.63 24 28.8 12].9] 1.38% 1.]] 10.74 0.45 27.27 21.5 586.3 7.18 2.51 0.67 0 2.96 0 TRUE 3.25 507.88 510.39 OK -2.52 116 14+64.93 507.88 8 2.03 37.64 2.42% 0.91 12.43 0.6 1.43 6.29 8.97 0.61 0.22 72.24 0.41 1.23 0 TRUE 1.52 509.4 512.63 OK -3.23 118 15+01.68 509.4 8 1.43 36.]5 1.19% 0.44 6.29 0.15 1.2] 5.]2 ].26 0.51 0.18 83.21 0.34 0.6] 0 TRUE 0.]] 510.1] 513.62 OK -3.45 120 15+p5.03 510.1] 8 1.2] 32.] 0.94% 0.31 5.]2 0.13 0 0 0 0 0 0 0 0.13 0.17 TRUE 0.39 510.56 512.95 OK -2.39 112 12+58.53 1 492.26 1 15 1 3.88 1258.831 0.31% 1 0.8 1 4.48 1 0.08 1 0.8 1 9.19 1 7.36 1 1.31 1 0.46 1 53.74 1 0.66 1 1.19 1 1.55 1 TRUE 1 1.57 1493.831 495.59 1 OK -1.75 126 13+19.42 1 493.83 1 15 1 0.8 1 60.9 1 0.01% 1 0.01 1 9.19 1 0.33 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0.33 1 0.43 1 TRUE 1 0.22 1 494.05 1 510.28 1 OK -16.22 106 12+01.66 500.49 18 2.73 24.35 0.06% 0.01 8.84 0.3 0 0 0 0 0 0 0 0.3 0.39 TRUE 0.21 500.7 500.73 OK 114 13+26.39 504.63 15 5.21 31.01 0.55% 0.17 6.26 0.15 0 0 0 0 0 0 0 0.15 0.2 TRUE 0.27 504.9 506.66 OK 110 15+63.74 507.88 1 24 1 2].2] 1110.031 1.24% 1 1.36 1 21.5 1 1.79 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 1.79 1 0 1 TRUE 1 2.26 1510.14 1 517.39 1 OK 122 10+31.00 509.4 1 8 1 0.66 1 31 1 0.25% 1 0.08 1 6.6 1 0.17 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0.17 1 0 1 TRUE 1 0.16 1509.571 512.71 1 OK -3.15 DFD Wryinb Bumff aaauama Memaa New kvelopmm[ Cumplbnre Sprevasheef [."ZOII BMPSbWaaaM Spaal4albu O 3013 Drefl BMP Stanaasas and SWcfl=lms Pmjest Dame: . Berkmar5eH5mrage M@: 2/15120zz BMPOesl9n sceeifirmuni tis[ 2013 Draft sWs & specs Site Information Post -Development Project (Treatment Volume and Loads) +aar—• mares Roils BS ils CSoi6 Dbils ..a +meaVDcen Wwl+aaal- ainumm, txieabrm/ope onAm¢realana Bronalaeml Om f amrbea,6raambr. ] n martnunmtrmowal/managal 1 D vae.l+aaal zm iM as) eoemams Bamen0on�1 an amaue.m EM Im DE)m 026 11 eoruT INIMC MCmC(aIm� I8G Tar¢nm Dm —rObp•reN0 91a� —n•m•I am .—VDpen"ere rme• br•eg B.m Wei8Metl 8e(Wee) am %Fdert U6 Managetl Tint Co+esbcrez� 1)) Weehmd Be ltuM 020 %Managetl Tue 3% Impxrvpus Caveslacrez� 2m 8e limpervmus� 095 %Imperviwz 61% S. Area lanes 4.57 3.0 TmaMennmumeanexWmnt Lames rreatmemvolam. I+a�rtl Dsslz Tre+4n.ittvobm+IsSRiareeal m9a1 TP baa Bb/Y•1 68] ]ta b+allb/pl Site Results (Water Quality Compliance) Area Checks FOREST/OPEN SPACE (at) D.A.A 0.00 DA.B 0.00 DA.0 am DA.D 0.00 0.0.E 0.00 AREACHECK OR. IMPERVIOUS COVER)a[) ON 0.00 am 0.00 0.00 OK. IMPERVOUS COVER TREATED)a[) MANAGED TURF AREA ON ON 0.00 0.00 am am 0.00 0.00 0.00 0.00 OR.. OR. MANAGED TURF AREA TREATED Ia[) 0.00 0.00 am 0.00 0.00 OR. ARFACHECK OK- OR. OR. OK- OR. Site Treatment Volume (ft') 10,941 Runoff Reduction Volume and TP By Drainage Area D.A. A D.A. B DA. C DA. D 0.0.E TOTAL RUNOFF REDUCTDAVAILO 0 0 0 0 0 LE FOR RE OV L (Ib/Yr) TP LOAD AVAILABLE FOR REMOVAL pb/yF) 0.00 O.W 0.00 � 0.00 O.W 0.00 TP LOAD REDUCTIONACHIEVED )Ib/yFl 0.00 Dw 0.00 0.00 O.W 0.00 TPLOAO REMAINING IIb/yr) 0.00 0A0 0.00 0.00 O.W 0.00 PUTROGENLOADREDUCTONACHIEVED (Ib/yr)IIII 0.00 0.00 0.00 0.00 O.W am Total Phosphorus FINAL POST -DEVELOPMENT TP LOAD (11b/yr) 6.87 TP LOAD REDUCTION REQUIRED jib/yr)ll 5.00 TP LOAD REDUCTION ACHIEVED pb/yrl ON TP LOAD REMAINING Qb/yrl:F 6.87 REMAINING TP LOAD REDUCTION REQUIRED (lb/yr): 5.00 Total Nitrogen (For Information Purposes) POST -DEVELOPMENT LOAD (Ib/yr) 49.18 NITROGEN LOAD REDUCTON ACHIEVED (Ib/yr)II 0.00 REMAINING POST -DEVELOPMENT NRRWEN LOAD (Ib/yr) 49.18 8S 9S OFFSITE E Berk ar Sef Storage 10P Keglers Regional Pond Subcat Reach On Link Routing Diagram for PRE _Keglers Regional Pond Prepared by Timmons Group, Printed 7/15/2022 FHydroCAD@ 10.10-4a s/n 08663 0 2020 HydroCAD Software Solutions LLC PRE _Keglers Regional Pond Prepared by Timmons Group Rainfall Events Listing (selected events) Event# Event Storm Type Curve Mode Duration B/B Depth AMC Name (hours) (inches) 1 1 year Type II 24-hr Default 24.00 1 3.01 2 2 10 year Type II 24-hr Default 24.00 1 5.50 2 Printed 7/15/2022 PRE _Keglers Regional Pond Type // 24-hr 1 year Rainfall=3.01" Prepared by Timmons Group Printed 7/15/2022 HydroCAD® 10.10-4a s/n 08663 ©2020 HydroCAD Software Solutions LLC Paae 3 Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment8S: OFFSITE PRE Runoff Area=65.050 ac 0.00% Impervious Runoff Depth>1.03" Flow Length=1,812' Tc=20.5 min CN=78 Runoff=78.36 cfs 5.561 of Subcatchment9S: BerkmarSef Storage Runoff Area=4.340 ac 0.00% Impervious Runoff Depth>0.34" Flow Length=627' Tc=16.7 min CN=62 Runoff=1.40 cfs 0.124 of Pond 10P: Keglers Regional Pond Peak Elev=466.24' Storage=56,482 cf Inflow=79.76 cfs 5.685 of Outflow=29.34 cfs 5.683 of Total Runoff Area = 69.390 ac Runoff Volume = 5.685 of Average Runoff Depth = 0.98" 100.00% Pervious = 69.390 ac 0.00% Impervious = 0.000 ac PRE _Keglers Regional Pond Prepared by Timmons Group Type // 24-hr 1 year Rainfall=3.01 " Printed 7/15/2022 Summary for Subcatchment 8S: OFFSITE PRE Runoff = 78.36 cfs @ 12.14 hrs, Volume= 5.561 af, Depth> 1.03" 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 1 year Rainfall=3.01" Area (ac) CN Description 15.400 92 LOWES 5.650 84 KEGLERS 36.320 70 DA_A 6.780 81 BERKMAR OVERLOOK B 0.900 66 BERKMAR OVERLOOK C 65.050 78 Weighted Average 65.050 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 20.5 1,812 1.47 Direct Entry, Subcatchment 8S: OFFSITE PRE Hydrograph 85 ❑Runoff 80: _ _ ____�____ 78 36 afs i___I_________ I I Type II 24-hr 75 1 year Rainfail=3.01" 65 ,- Runoff Area=65.050 60 -- --- -ac 55 - ---1I, _---III-- ---II-Runoff Volume=5.561 of w y 45 l Runoff Depth>1.03" F — yl 2 46 Flow Length=1,812' 35 i ---- IL---JI-_- -_ Tc=20.5 min 3 25 CN=78 20 ------------ - - - - -� --- --- -- 15 10 1 12 13 Time (hours) PRE _Keglers Regional Pond Prepared by Timmons Group Type // 24-hr 1 year Rainfall=3.01 " Printed 7/15/2022 Summary for Subcatchment 9S: Berkmar Sef Storage Runoff = 1.40 cfs @ 12.14 hrs, Volume= 0.124 af, Depth> 0.34" 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 1 year Rainfall=3.01" Area (ac) CN Description * 4.340 62 Pre Dev 4.340 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 11.0 100 0.0900 0.15 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.64" 2.0 167 0.0814 1.43 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 3.7 360 0.0527 1.64 131.20 Channel Flow, Area= 80.0 sf Perim= 30.0' r= 2.67' n= 0.400 Sheet flow: Woods+lioht brush 16.7 627 Total Subcatchment 9S: Berkmar Sef Storage Hydrograph ❑ Runoff Type II 24-hr 1 year Rainfall=3.01" Runoff Area=4.340 ac Runoff Volume=0.124 of Runoff Depth>0.34" Flow Length=627' Tc=16.7 min CN=62 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Time (hours) PRE _Keglers Regional Pond Type // 24-hr 1 year Rainfall=3.01" Prepared by Timmons Group Printed 7/15/2022 HydroCAD@ 10.10-4a s/n 08663 @ 2020 HydroCAD Software Solutions LLC Page 6 Summary for Pond 10P: Keglers Regional Pond Inflow Area = 69.390 ac, 0.00% Impervious, Inflow Depth > 0.98" for 1 year event Inflow = 79.76 cfs @ 12.14 hrs, Volume= 5.685 of Outflow = 29.34 cfs @ 12.46 hrs, Volume= 5.683 af, Atten= 63%, Lag= 18.7 min Primary = 29.34 cfs @ 12.46 hrs, Volume= 5.683 of Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 466.24' @ 12.46 hrs Surf.Area= 16,901 sf Storage= 56,482 cf Plug -Flow detention time=12.8 min calculated for 5.664 of (100% of inflow) Center -of -Mass det. time= 12.6 min ( 826.4 - 813.8 ) Volume Invert Avail.Storage Storage Description #1 452.50' 679,440 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 452.50 0 0 0 456.00 167 292 292 458.00 416 583 875 460.00 2,064 2,480 3,355 462.00 5,271 7,335 10,690 464.00 10,213 15,484 26,174 466.00 16,142 26,355 52,529 468.00 22,487 38,629 91,158 470.00 28,785 51,272 142,430 472.00 35,810 64,595 207,025 474.00 42,431 78,241 285,266 476.00 60,902 103,333 388,599 478.00 72,821 133,723 522,322 479.00 78,951 75,886 598,208 480.00 83,513 81,232 679,440 Device Routing Invert Outlet Devices #1 Primary 452.30' 36.0" Round Culvert L= 480.0' RCP, end -section conforming to fill, Ke= 0.500 Inlet / Outlet Invert= 452.30' / 442.70' S= 0.0200 '/' Cc= 0.900 n= 0.013, Flow Area= 7.07 sf #2 Device 1 453.60' 18.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Device 1 470.00' 12.6' long Sharp -Crested Rectangular Weir End Contraction(s) #4 Primary 479.10' 100.0' long x 1.00' rise Sharp -Crested Rectangular Weir 2 End Contraction(s) 1.0' Crest Height Primary OutFlow Max=29.34 cfs @ 12.46 hrs HW=466.24' (Free Discharge) 1=Culvert (Passes 29.34 cfs of 115.14 cfs potential flow) �2=Orifice/Grate (Orifice Controls 29.34 cfs @ 16.60 fps) 3=Sharp-Crested Rectangular Weir( Controls 0.00 cfs) =Sharp -Crested Rectangular Weir( Controls 0.00 cfs) irs Regional Pond Type 11 24-hr 1 year Rainfall=3.01 " Timmons Group Printed 7/15/2022 ).10-4a s/n 08663 02020 HydroCAD Software Solutions LLC Page 7 Pond 10P: Keglers Regional Pond Hydrograph I I I I I I I I I I I I I I E TIM T____I____r___r �.�� I i ___T____I____r____I____r ___ Primary _--Inflw-Areor-09.30 �c- 6 75 ' --------;----; -Pe-lT (l-E-I V-Y 4-6� 6:2-r4 k= - 70 I ;; 65 fi82cf_ ra= 60 I 55 '' _L _ .@ 50 3 45 0 40 I 35 30 25 ' ---�----r---r----r---r---r-----r---r----r---r---�----r--- , ____r___T____I____r_ __. 20 I I I I I 15 I I I I I I 1 12 13 Time (hour) PRE _Keglers Regional Pond Type // 24-hr 10 year Rainfall=5.50" Prepared by Timmons Group Printed 7/15/2022 HydroCAD® 10.10-4a s/n 08663 ©2020 HydroCAD Software Solutions LLC Paoe 8 Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment8S: OFFSITE PRE Runoff Area=65.050 ac 0.00% Impervious Runoff Depth>2.89" Flow Length=1,812' Tc=20.5 min CN=78 Runoff=222.84 cfs 15.691 of Subcatchment9S: BerkmarSef Storage Runoff Area=4.340 ac 0.00% Impervious Runoff Depth>1.58" Flow Length=627' Tc=16.7 min CN=62 Runoff=8.87 cfs 0.570 of Pond 10P: Keglers Regional Pond Peak Elev=471.78' Storage=199,316 cf Inflow=231.41 cfs 16.261 of Outflow=127.48 cfs 16.259 of Total Runoff Area = 69.390 ac Runoff Volume = 16.261 of Average Runoff Depth = 2.81" 100.00% Pervious = 69.390 ac 0.00% Impervious = 0.000 ac PRE _Keglers Regional Pond Prepared by Timmons Group Type/1 24-hr 10 year Rainfall=5.50" Printed 7/15/2022 Summary for Subcatchment 8S: OFFSITE PRE Runoff = 222.84 cfs @ 12.13 hrs, Volume= 15.691 af, Depth> 2.89" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, l 0.05 hrs Type II 24-hr 10 year Rainfall=5.50" Area (ac) CN Description 15.400 92 LOWES ' 5.650 84 KEGLERS ' 36.320 70 DA_A ' 6.780 81 BERKMAR OVERLOOK B ' 0.900 66 BERKMAR OVERLOOK C 65.050 78 Weighted Average 65.050 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 20.5 1,812 1.47 Direct Entry, Subcatchment 8S: OFFSITE PRE Hydrograph --`----`----- - - ------------`-----`---`---- �___ �___ �___ �___ �___ i____ ■Runoff 240 __ ___ ___ ___ ___ __ __ -r -r -� -r -i -r -� -Y -i -Y -r -Y -r -r 230 ___J____L___ i____L___ i____i zzz ea cfs __L____L___ J____ L___ J____ L___J____ 220 --_y____r___ i____r____i____r__--__1____r___y____-TY24�hr 210- C-__ 200 ; year �,Rail�faH=5.AY 190 --- -- -- - -- - - -- - --- - - ---- -----10 130 J L-------------- RunoffAreaT65�O at:- 160 ---�,----; --- ----;--------1-- --- IRnttoffi/ahillmer7S'jgtaf- 150 --- T----r----r---r------- - ----T----r---r----r---r----r---r---_ 140 ' L --- --I ----',-13jrnfiDpthy:�9"- 3 ,20 1 f M1m ow a th=1 -------r----------------`----'----�---- - -- --- -- - -�---- ,00 ' --- r-- 90 ---r----r--- 80 ___r____r____i____r____i____r_ _r____r___r____r___r---- Ct ��_ R 60 ___J____L___I____L___I___ -- ______ --_- -------------------- 20 - - ---- -- - --- ,o Time (houB) PRE _Keglers Regional Pond Prepared by Timmons Group Type/1 24-hr 10 year Rainfall=5.50" Printed 7/15/2022 Summary for Subcatchment 9S: Berkmar Sef Storage Runoff = 8.87 cfs @ 12.10 hrs, Volume= 0.570 af, Depth> 1.58" 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 10 year Rainfall=5.50" Area (ac) CN Description * 4.340 62 Pre Dev 4.340 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 11.0 100 0.0900 0.15 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.64" 2.0 167 0.0814 1.43 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 3.7 360 0.0527 1.64 131.20 Channel Flow, Area= 80.0 sf Perim= 30.0' r= 2.67' n= 0.400 Sheet flow: Woods+lioht brush 16.7 627 Total Subcatchment 9S: Berkmar Sef Storage Hydrograph 9 8 87 d, Type II 24-hr 8 10 year Rainfall=5.50" 7 Runoff Area=4.340 ac 6 Runoff Volume=0.570 of 5 Runoff Depth>1.58" LL Flow Length=627' 4 Tc=16.7 min 3 CN=62 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) ❑ Runoff PRE _Keglers Regional Pond Type // 24-hr 10 year Rainfall=5.50" Prepared by Timmons Group Printed 7/15/2022 HydroCAD@ 10.10-4a s/n 08663 @ 2020 HydroCAD Software Solutions LLC Page 11 Summary for Pond 10P: Keglers Regional Pond Inflow Area = 69.390 ac, 0.00% Impervious, Inflow Depth > 2.81" for 10 year event Inflow = 231.41 cfs @ 12.13 hrs, Volume= 16.261 of Outflow = 127.48 cfs @ 12.33 hrs, Volume= 16.259 af, Atten= 45%, Lag= 11.9 min Primary = 127.48 cfs @ 12.33 hrs, Volume= 16.259 of Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 471.78' @ 12.33 hrs Surf.Area= 35,046 sf Storage= 199,316 cf Plug -Flow detention time= 30.2 min calculated for 16.204 of (100% of inflow) Center -of -Mass det. time= 30.1 min ( 822.2 - 792.2 ) Volume Invert Avail.Storage Storage Description #1 452.50' 679,440 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 452.50 0 0 0 456.00 167 292 292 458.00 416 583 875 460.00 2,064 2,480 3,355 462.00 5,271 7,335 10,690 464.00 10,213 15,484 26,174 466.00 16,142 26,355 52,529 468.00 22,487 38,629 91,158 470.00 28,785 51,272 142,430 472.00 35,810 64,595 207,025 474.00 42,431 78,241 285,266 476.00 60,902 103,333 388,599 478.00 72,821 133,723 522,322 479.00 78,951 75,886 598,208 480.00 83,513 81,232 679,440 Device Routing Invert Outlet Devices #1 Primary 452.30' 36.0" Round Culvert L= 480.0' RCP, end -section conforming to fill, Ke= 0.500 Inlet / Outlet Invert= 452.30' / 442.70' S= 0.0200 '/' Cc= 0.900 n= 0.013, Flow Area= 7.07 sf #2 Device 1 453.60' 18.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Device 1 470.00' 12.6' long Sharp -Crested Rectangular Weir End Contraction(s) #4 Primary 479.10' 100.0' long x 1.00' rise Sharp -Crested Rectangular Weir 2 End Contraction(s) 1.0' Crest Height Primary OutFlow Max=129.71 cfs @ 12.33 hrs HW=471.77' (Free Discharge) 1=Culvert (Passes 129.71 cfs of 129.73 cfs potential flow) �2=Orifice/Grate (Orifice Controls 35.51 cfs @ 20.10 fps) 3=Sharp-Crested Rectangular Weir(Weir Controls 94.20 cfs @ 4.35 fps) =Sharp -Crested Rectangular Weir( Controls 0.00 cfs) 0 LL Irs Regional Pond Type 1124-hr 10 year Rainfa&5.50" Timmons Group Printed 7/15/2022 ).10-4a s/n 08663 02020 HydroCAD Software Solutions LLC Page 12 Pond 10P: Keglers Regional Pond Hydrograph I I ' ' I I I ' ' ■ Inflow y ■ Primary ---,1nfjowl,Area-".3,9a 4c ---L---I- I----L---J----L---L--- Peiak Elev=471.78' - - - Sto rage=9-08a316 :cf_ i I i i I I I i i _-- - -I I i i 1 12 13 14 Time (hours) 8S (9s) OFFSITE P T Berk ar Sef Storage POST 10P Keglers Regional Pond Subcat Reach On Link Routing Diagram for POST _Keglers Regional Pond Prepared by Timmons Group, Printed 7/15/2022 FHydroCAD@ 10.10-4a s/n 08663 0 2020 HydroCAD Software Solutions LLC POST _Keglers Regional Pond Prepared by Timmons Group Rainfall Events Listing (selected events) Event# Event Storm Type Curve Mode Duration B/B Depth AMC Name (hours) (inches) 1 1 year Type II 24-hr Default 24.00 1 3.01 2 2 10 year Type II 24-hr Default 24.00 1 5.50 2 Printed 7/15/2022 POST _Keglers Regional Pond Prepared by Timmons Group Type // 24-hr 1 year Rainfall=3. 01 " Printed 7/15/2022 Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment8S: OFFSITE POST Runoff Area=65.050 ac 0.00% Impervious Runoff Depth>1.03" Flow Length=1,812' Tc=20.5 min CN=78 Runoff=78.36 cfs 5.561 of Subcatchment9S: BerkmarSef Storage Runoff Area=4.340 ac 0.00% Impervious Runoff Depth>1.69" Tc=9.6 min CN=88 Runoff=12.09 cfs 0.613 of Pond 10P: Keglers Regional Pond Peak Elev=467.63' Storage=83,037 cf Inflow=83.93 cfs 6.174 of Outflow=21.63 cfs 6.172 of Total Runoff Area = 69.390 ac Runoff Volume = 6.174 of Average Runoff Depth = 1.07" 100.00% Pervious = 69.390 ac 0.00% Impervious = 0.000 ac POST _Keglers Regional Pond Prepared by Timmons Group Type // 24-hr 1 year Rainfall=3.01 " Printed 7/15/2022 Summary for Subcatchment 8S: OFFSITE POST Runoff = 78.36 cfs @ 12.14 hrs, Volume= 5.561 af, Depth> 1.03" 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 1 year Rainfall=3.01" Area (ac) CN Description 15.400 92 LOWES 5.650 84 KEGLERS 36.320 70 AREA A 6.780 81 BERKMAR OVERLOOK B 0.900 66 BERKMAR OVERLOOK C 65.050 78 Weighted Average 65.050 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 20.5 1,812 1.47 Direct Entry, Subcatchment 8S: OFFSITE POST Hydrograph 85 ❑Runoff 80 _ _ ____�____ 78 3fi afs --- ---- ------ I I Type II 24-hr 75 1 year Rainfail=3.01" 65 ,- Runoff Area=65.050 60 -- --- -ac 55 - ---1I, _---III-- ---II-Runoff Volume=5.561 of w y 45 l Runoff Depth>1.03" F — yl 2 46 Flow Length=1,812' 35 i ---- IL---JI-_- -_ Tc=20.5 min 3 25 CN=78 20 ------------ - - - - -� --- --- -- 15 10 1 12 13 Time (hours) POST _Keglers Regional Pond Prepared by Timmons Group Type // 24-hr 1 year Rainfall=3.01 " Printed 7/15/2022 Summary for Subcatchment 9S: Berkmar Sef Storage POST Runoff = 12.09 cfs @ 12.01 hrs, Volume= 0.613 af, Depth> 1.69" 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 1 year Rainfall=3.01" Area (ac) CN Description * 4.340 88 POST Dev 4.340 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 9.6 Direct Entry, Subcatchment 9S: Berkmar Sef Storage POST Hydrograph 13 ---------------------I--- 12 '�----------------------- - - 'I-- 11 ---------- --- -- - 0 i i I I I 9 8 N V 7 3 ---I- ° 6 II LL 5 4 ----------- - -- - ----------�- 3 I i i i i I I I 2 Type II 24-hr 1 year Rainfall=3.01 rr Runoff Area=4.340 ac Runoff Volume=0.613 of Runoff Depth>1.69" Tc=9.6 min AMU 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) ❑ Runoff POST _Keglers Regional Pond Prepared by Timmons Group Type // 24-hr 1 year Rainfall=3. 01 " Summary for Pond 10P: Keglers Regional Pond Printed 7/15/2022 Inflow Area = 69.390 ac, 0.00% Impervious, Inflow Depth > 1.07" for 1 year event Inflow = 83.93 cfs @ 12.13 hrs, Volume= 6.174 of Outflow = 21.63 cfs @ 12.57 hrs, Volume= 6.172 af, Atten= 74%, Lag= 26.8 min Primary = 21.63 cfs @ 12.57 hrs, Volume= 6.172 of Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 467.63' @ 12.57 hrs Surf.Area= 21,311 sf Storage= 83,037 cf Plug -Flow detention time= 28.9 min calculated for 6.172 of (100% of inflow) Center -of -Mass det. time= 28.8 min ( 838.3 - 809.4 ) Volume Invert Avail.Storage Storage Description #1 452.50' 679,440 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 452.50 0 0 0 456.00 167 292 292 458.00 416 583 875 460.00 2,064 2,480 3,355 462.00 5,271 7,335 10,690 464.00 10,213 15,484 26,174 466.00 16,142 26,355 52,529 468.00 22,487 38,629 91,158 470.00 28,785 51,272 142,430 472.00 35,810 64,595 207,025 474.00 42,431 78,241 285,266 476.00 60,902 103,333 388,599 478.00 72,821 133,723 522,322 479.00 78,951 75,886 598,208 480.00 83,513 81,232 679,440 Device Routing Invert Outlet Devices #1 Primary 452.30' 36.0" Round Culvert L= 480.0' RCP, end -section conforming to fill, Ke= 0.500 Inlet / Outlet Invert= 452.30' / 442.70' S= 0.0200 '/' Cc= 0.900 n= 0.013, Flow Area= 7.07 sf #2 Device 1 453.60' 15.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Device 1 471.00' 12.6' long Sharp -Crested Rectangular Weir End Contraction(s) #4 Primary 479.00' 100.0' long x 1.00' rise Sharp -Crested Rectangular Weir 2 End Contraction(s) 1.0' Crest Height Primary OutFlow Max=21.63 cfs @ 12.57 hrs HW=467.63' (Free Discharge) 1=Culvert (Passes 21.63 cfs of 118.97 cfs potential flow) �2=Orifice/Grate (Orifice Controls 21.63 cfs @ 17.63 fps) 3=Sharp-Crested Rectangular Weir( Controls 0.00 cfs) =Sharp -Crested Rectangular Weir( Controls 0.00 cfs) POST _Keglers Regional Pond Prepared by Timmons Grow Type 11 24-hr 1 year Rainfall=3.01 " Printed 7/15/2022 Pond 10P: Keglers Regional Pond Hydrograph ' L___ ■Inflow Primary I I I I I I I II I --- i---L--An¢wAreO60-300 Ol 65 ' ---J-- - ---J--------L---J----L80 � , , J----IIIPE -4 EWV67.63` 75 75 I I I I I I 70 �, ---------Illstor=$3i�37-icf- 65 ,' ___J____I____1____I____L___J__ __J____I____L_�__LS, J____L___ 60 ,'_L _J _J _I _1 50 , ___J____I____L____I____L___J____J____I____L____I____L___J____L___ 0 45 LL 40 35 30 I I I I I I 25 2163 , _ 40 , I I in 1 12 13 Time (hour) POST _Keglers Regional Pond Prepared by Timmons Group Type/1 24-hr 10 year Rainfall=5.50" Printed 7/15/2022 Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment8S: OFFSITE POST Runoff Area=65.050 ac 0.00% Impervious Runoff Depth>2.89" Flow Length=1,812' Tc=20.5 min CN=78 Runoff=222.84 cfs 15.691 of Subcatchment9S: BerkmarSef Storage Runoff Area=4.340 ac 0.00% Impervious Runoff Depth>3.88" Tc=9.6 min CN=88 Runoff=26.45 cfs 1.404 of Pond 10P: Keglers Regional Pond Peak Elev=472.82' Storage=237,484 cf Inflow=236.34 cfs 17.095 of Outflow=123.76 cfs 17.093 of Total Runoff Area = 69.390 ac Runoff Volume = 17.095 of Average Runoff Depth = 2.96" 100.00% Pervious = 69.390 ac 0.00% Impervious = 0.000 ac POST _Keglers Regional Pond Prepared by Timmons Group Type/1 24-hr 10 year Rainfall=5.50" Printed 7/15/2022 Summary for Subcatchment 8S: OFFSITE POST Runoff = 222.84 cfs @ 12.13 hrs, Volume= 15.691 af, Depth> 2.89" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, l 0.05 hrs Type II 24-hr 10 year Rainfall=5.50" Area (ac) CN Description 15.400 92 LOWES ' 5.650 84 KEGLERS ' 36.320 70 AREA A ' 6.780 81 BERKMAR OVERLOOK B ' 0.900 66 BERKMAR OVERLOOK C 65.050 78 Weighted Average 65.050 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 20.5 1,812 1.47 Direct Entry, Subcatchment 8S: OFFSITE POST Hydrograph --`----`----- - - ------------`-----`---`---- �___ �___ �___ �___ �___ i____ ■Runoff 240 __ ___ ___ ___ ___ __ __ -r -r -� -r -i -r -� -Y -i -Y -r -Y -r -r 230 ___J____L___ i____L___ i____i zzz ea cfs __L____L___ J____ L___ J____ L___J____ 220 --_y____r___ i____r____i____r__--__1____r___y____-TY24�hr 210- C-__ 200 ; year �,Rail�faH=5.AY 190 --- -- -- - -- - - -- - --- - - ---- -----10 130 J L-------------- RunoffAreaT65�O at:- 160 ---�,----; --- ----;--------1-- --- IRnttoffi/ahillmer7S'jgtaf- 150 --- T----r----r---r------- - ----T----r---r----r---r----r---r---_ 140 ' L --- --I ----',-13jrnfiDpthy:�9"- 3 ,20 1 f M1m ow a th=1 -------r----------------`----'----�---- - -- --- -- - -�---- ,00 --- r-- 90 ---r----r--- 80 ___r____r____i____r____i____r_ _r____r___r____r___r---- Ct ��_ R 60 ___J____L___I____L___I___ -- ______ --_- -------------------- 20 - - ---- -- - --- ,o Time (houB) POST _Keglers Regional Pond Prepared by Timmons Group Type/1 24-hr 10 year Rainfall=5.50" Printed 7/15/2022 Summary for Subcatchment 9S: Berkmar Sef Storage POST Runoff = 26.45 cfs @ 12.01 hrs, Volume= 1.404 af, Depth> 3.88" 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 10 year Rainfall=5.50" Area (ac) CN Description * 4.340 88 POST Dev 4.340 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 9.6 Direct Entry, Subcatchment 9S: Berkmar Sef Storage POST 26 I I I 24 22 ' ----I---- ----II- - - - 20 ' I I 8 I I I H ' -1 -T -i u 16 0 14 I I I 12 10 I I I 8 I I I 6 --- 4 I I I 7-. Hydrograph _ _I----�----*---- i----+---- r--- �- ❑Runoff I I I I I Type II 24-hr --;-- --- -10 year Rainfall=5.50rr -- - Runoff Area=4.340ac- ---- -- -I Ru' offVorum/r`� 1:'404;af T Runoff Dep t�--3.8pp I --7- Tc=-9l-6-Min-- .I I -1 T 10 11 12 13 14 15 16 17 18 19 20 Time (hours) POST _Keglers Regional Pond Prepared by Timmons Group Type/1 24-hr 10 year Rainfall=5.50" Summary for Pond 10P: Keglers Regional Pond Printed 7/15/2022 Inflow Area = 69.390 ac, 0.00% Impervious, Inflow Depth > 2.96" for 10 year event Inflow = 236.34 cfs @ 12.12 hrs, Volume= 17.095 of Outflow = 123.76 cfs @ 12.34 hrs, Volume= 17.093 af, Atten= 48%, Lag= 13.2 min Primary = 123.76 cfs @ 12.34 hrs, Volume= 17.093 of Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 472.82' @ 12.34 hrs Surf.Area= 38,523 sf Storage= 237,484 cf Plug -Flow detention time= 53.8 min calculated for 17.092 of (100% of inflow) Center -of -Mass det. time= 53.7 min ( 842.3 - 788.6 ) Volume Invert Avail.Storage Storage Description #1 452.50' 679,440 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 452.50 0 0 0 456.00 167 292 292 458.00 416 583 875 460.00 2,064 2,480 3,355 462.00 5,271 7,335 10,690 464.00 10,213 15,484 26,174 466.00 16,142 26,355 52,529 468.00 22,487 38,629 91,158 470.00 28,785 51,272 142,430 472.00 35,810 64,595 207,025 474.00 42,431 78,241 285,266 476.00 60,902 103,333 388,599 478.00 72,821 133,723 522,322 479.00 78,951 75,886 598,208 480.00 83,513 81,232 679,440 Device Routing Invert Outlet Devices #1 Primary 452.30' 36.0" Round Culvert L= 480.0' RCP, end -section conforming to fill, Ke= 0.500 Inlet / Outlet Invert= 452.30' / 442.70' S= 0.0200 '/' Cc= 0.900 n= 0.013, Flow Area= 7.07 sf #2 Device 1 453.60' 15.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Device 1 471.00' 12.6' long Sharp -Crested Rectangular Weir End Contraction(s) #4 Primary 479.00' 100.0' long x 1.00' rise Sharp -Crested Rectangular Weir 2 End Contraction(s) 1.0' Crest Height Primary OutFlow Max=122.93 cfs @ 12.34 hrs HW=472.81' (Free Discharge) 1=Culvert (Passes 122.93 cfs of 132.29 cfs potential flow) �2=Orifice/Grate (Orifice Controls 25.47 cfs @ 20.76 fps) 3=Sharp-Crested Rectangular Weir(Weir Controls 97.46 cfs @ 4.40 fps) =Sharp -Crested Rectangular Weir( Controls 0.00 cfs) POST _Keglers Regional Pond Prepared by Timmons Grow Type 1124-hr 10 year Rainfa&5.50" Pond 10P: Keglers Regional Pond Hydrograph 260 ---- ---q---------------�--- -----------L---J--------i I - I I I z3e.r 240 --------------'--------'-- 220 -' 180 , __-----1i- - - -- I ---- ---- I ------ I I 160 140 -a -I -� 3 , � I I I I I I 123,76, I 120 LL , I 40 , ___-____II____�___�____I____i Printed 7/15/2022 y--------------------------`---T--- I I I I I I I I I I I I I I ■ Inflow --`--------------�I-------i--- ■Primary --- nfjowll: A►r4a=$9.39a0c -RaA-Efev=4'72.82' _5toFla 0=27,84 cf_ I I _L _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 _1 1 12 13 14 Time (hours) Worksheet for Downstream Channel 2 yr Project Description Friction Method Manning Formula Solve For Normal Depth Input Data Roughness Coefficient 0.050 Channel Slope 0.060 ft/ft Left Side Slope 2.000 H:V Right Side Slope 2.000 H:V Discharge 23.79 cis Results Normal Depth 17.6 in Flow Area 4.3 ft2 Wetted Perimeter 6.6 ft Hydraulic Radius 7.9 in Top Width 5.88 ft Critical Depth 18.5 in Critical Slope 0.046 ft/ft Velocity 5.50 ft/s Velocity Head 0.47 ft Specific Energy 1.94 ft Froude Number 1.132 Flow Type Supercritical 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 17.6 in Critical Depth 18.5 in Channel Slope 0.060 ft/ft Critical Slope 0.046 ft/ft Bentley Systems, Inc. Haestad Methods Solution FlowMaster Untitledi.1m8 Center [10.03.00.031 7/19/2022 27 Siemon Company Drive Suite 200 W Page 1 of 1 Watertown, CT 06795 USA +1-203-755-1666 Worksheet for Downstream Channel 10 yr Project Description Friction Method Manning Formula Solve For Normal Depth Input Data Roughness Coefficient 0.050 Channel Slope 0.060 ft/ft Left Side Slope 2.000 H:V Right Side Slope 2.000 H:V Discharge 41.01 cis Results Normal Depth 21.6 in Flow Area 6.5 ft2 Wetted Perimeter 8.1 ft Hydraulic Radius 9.7 in Top Width 7.21 ft Critical Depth 23.0 in Critical Slope 0.043 ft/ft Velocity 6.31 ft/s Velocity Head 0.62 ft Specific Energy 2.42 ft Froude Number 1.171 Flow Type Supercritical 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 21.6 in Critical Depth 23.0 in Channel Slope 0.060 ft/ft Critical Slope 0.043 ft/ft Bentley Systems, Inc. Haestad Methods Solution FlowMaster Untitledi.1m8 Center [10.03.00.031 7/19/2022 27 Siemon Company Drive Suite 200 W Page 1 of 1 Watertown, CT 06795 USA +1-203-755-1666 ECOSYSTEM SERVICES, LLC 1102 Carlton Avenue Charlottesville, VA 22902 540.578.4296 www.ecosystemservices.us ion@ecosystemservices.us July 7, 2022 Riki van Niekirk Project Engineer TIMMONS GROUP 608 Preston Avenue, Suite 300 Charlottesville, VA 22903 RE: Nutrient Offset Credit — Credit Availability Letter Project: Berkmar Self Storage and Hotel Project TMP: 04500-00-00112EO and 04500-00-0011200 Project Address: Berkmar Drive, Charlottesville, VA 22903 Project HUC: 02080204 Bank HUC:02080204 Bank Address: 1705 Lambs Road, Charlottesville, VA 22901 Dear Riki, We appreciate the opportunity to provide a credit availability letter for 5.00 pounds of phosphorus for the above referenced project. This letter is to certify that as of today, July 7, 2022, Ivy Creek Nutrient Bank has 163.65 pounds of phosphorus (TP), 251.83 pounds of nitrogen (TN), and 51,603.97 pounds of TSS available fortransferto 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 5.00 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: Jonathan R. Roller, AOSE PSS CNMP Manager —Authorized Representative