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HomeMy WebLinkAboutWPO200500074 Calculations 2005-08-13 University Village : Phase III Addition STORMWATER MANAGEMENT ENGINEERING CALCULATIONS County of Albemarle, Virginia Prepared for : MD Development , LLC 1 Boar ' s Head Pointe Charlottesville , Virginia 22903 Prepared by: FiFt"r-•gig ,. .� ,. . 4EP 1 2 ..a15 The Cox Company 220 East High Street COMtvs'k3 = ",' Charlottesville, Virginia 22902 September 12, 2005 Stile TABLE OF CONTENTS DIVISION 1 — Stormwater Management DIVISION 2 — Storm Pipe Calculations DIVISION 3 — Storm Inlet Calculations The Cox Company University Village 03-140 Phase III DIVISION 1 — Stormwater Management • The Cox Company University Village 03-140 Phase III Storm Water Management Summary The site, as proposed, will primarily drain surface storm water off into two watersheds. Within the storm piping calculations, the sub areas are described as the western reach and the eastern reach. There are different methods of treating storm water for each sub area. During initial planning, the western sub area was designed and intended to be captured and treated in the existing large storm retention basin located downstream from the site adjacent to U.S. 29. However, VDOT assumed responsibility for this basin upon taking the land in a right of way acquisition. As a result of this taking, University Village was unsuccessful in obtaining an easement to the existing facility that they built. Therefore, phase III of the development will now be treated on-site. There were three key limitations placed on establishing the location for the on-site facility for the western sub area. The current residents were very optimistic that the developer could site the facility to: 1) Eliminate the need to clear existing large trees. 2) Limit the disturbance to the existing trail network on-site. 3) Provide a reasonably attractive storm water management facility. The assumption for the residents was that this could hopefully be done without significantly increasing the cost or size of the facility due to the constraints. The resultant biofilter shown on the plan was designed with these limitations in mind. The largest and most desirable existing trees were spared and the disturbance to the general layout of the trail network will remain generally intact. The use of the biofilter also provides additional vegetation in an area of the site that matches the use. The use of the biofilter in combination with permanent check dams in the spillway provides water quality treatment for all storm events and minimizes earthwork adjacent to specimen trees. The critical storm durations were calculated for the 2, 10 and 100-year storms. The implementation of the proposed biofilter with spillway will yield a peak rate of runoff that will be less than the existing peak rate of flow. Hydrographs for each storm event are included within the calculations. The basin is also sized to capture two times the required treatment volume as calculated using the modified simple method worksheet. The eastern sub area is currently within the watershed of an existing storm water management basin on University Village property. Water quality for the impervious areas will be treated by the use of two "Filterra" precast storm treatment structures. Surface areas at this site meet the manufacturers specification for treatable area. Stone outlet protection is also proposed at the outlet of the existing pipe network that the eastern sub area surface area drains into. The pipe currently outfalls into a grass lined swale. c Short Version BMP Computations For Worksheets 2 -6 Albemarle County Water Protection Ordinance: Modified Simple Method Plan: University Village: Phase Ill Water Resources Area: Development area Preparer: Eric Woolley, PE Date: 31-Aug-05 Project Drainage Area Designation New Area A h1€4 t r 1 L storm pollutant export in pounds, L= [P(Pj)Rv/12 j[C(A)2.72 Rv mean runoff coefficient, Rv=0.05+0.009(1) Pj small storm correction factor,0.9 1 percent imperviousness P annual precipitation,43"in Albemarle A project area in acres in subject drainage area, A= 1.60 C pollutant concentration,mg/I or ppm target phosphorus f factor applied to RR V required treatment volume in cy,0.5"over imperv.area= A(1)43560(0.5/12)/27 RR required removal , L(post)-f x L(pre) %RR removal efficiency, RR100/L(post) Impervious Cover Computation(values in feet&square feet) Item pre-development Area post-development Area Roads Length Width subtotal Length Width subtotal 0 0 0 0 0 15465 0 0 0 0 0 0 0 0 0 0 0 0 0 15465 Driveways Length Width no. subtotal Length Width no. subtotal and walks 0 0 0 0 53 5 1 265 0 0 0 0 67 5 1 335 0 0 0 0 0 0 600 Parking Lots 1 2 3 4 1 2 3 4 0 0 0 0 0 0 Gravel areas Area Area 0 x0.70= 0 x0.70= 0 Structures Area no. subtotal Area no. subtotal 0 0 0 21390 1 21390 0 0 0 0 0 0 0 0 0 0 0 21390 Actively-grazed pasture& Area Area yards and cultivated turf 31865 x 0.08= 2549.2 11716 x 0.08= 937.28 Active crop land Area Area x0.25= 0 x0.25= 0 Other Impervious Areas 0 0 Impervious Cover 4% 55% I(pre) ((post) Rv(post) V 0.55 59.2 New Development(For Development Areas,existing impervious cover<=20%) C f I(pre)* Rv(pre) L(pre) L(post) RR %RR Area Type 0.70 1.00 20% 0.23 2.25 5.36 3.10 58% Development Area 0.35 1.00 0% 0.08 0.41 2.68 2.27 85% Drinking Water Watersheds 0.40 1.00 1% 0.08 0.46 3.06 2.60 85% Other Rural Land *min.values Redevelopment(For Development Areas,existing impervious cover>20%) C f I(pre)* Rv(pre) L(pre) L(post) RR %RR Area Type 0.70 0.90 20% 0.23 2.25 5.36 3.33 62% Development Area 0.35 0.85 0% 0.08 0.41 2.68 2.33 87% Drinking Water Watersheds 0.40 0.85 1% 0.08 0.46 3.06 2.67 87% Other Rural Land Interim Manual, Page 70 rev. 16 Feb 1998 GEB Table of Contents Table of Contents ********************** MASTER SUMMARY ********************** Watershed Mod. Rational Grand Summary 1 .01 Master Network Summary 1 .02 ********************** RAINFALL DATA *********************** Alb 100yr 100yr I-D-F Table 2 .01 Alb 10yr 10yr I-D-F Table 2.02 Alb 2yr 2yr I-D-F Table 2 .03 ********************** TC CALCULATIONS ********************* EXISTING Tc Calcs 3 .01 STR. PIPE ROUTED Tc Calcs 3 .03 *********************** POND VOLUMES *********************** ON-SITE BASIN. . . Vol : Elev-Area 4.01 *********************** POND ROUTING *********************** CONTROL DEVICE. . 2yr Diverted Hydrograph 5 .01 S/N: E21401D06A89 The Cox Company PondPack Ver . 7. 5 (786c) Compute Time: 11 :43 : 39 Date: 09/12/2005 Table of Contents ii Table of Contents (continued) CONTROL DEVICE . . 10yr Diverted Hydrograph 5 .02 CONTROL DEVICE . . 100yr Diverted Hydrograph 5 .03 ON-SITE BASIN. . . Pond Infiltration Calcs 5 .04 ****************** RATIONAL METHOD CALCS ******************* MOD.RATIONAL . . . . 2yr Mod. Rational Graph 6.01 Mod. Rational Storm Calcs 6.02 MOD.RATIONAL . . . . 10yr Mod. Rational Graph 6.03 Mod. Rational Storm Calcs 6 .04 MOD.RATIONAL . . . . 100yr Mod. Rational Graph 6 .05 Mod. Rational Storm Calcs 6.06 PROP . RATIONAL . . C and Area 6.07 S/N: E21401D06A89 The Cox Company PondPack Ver . 7 . 5 (786c) Compute Time: 11 :43 : 39 Date: 09/12/2005 Type. . . . Mod. Rationaand Summary Page 1 .01 Name. . . . Watershed File. . . . D: \COXWOOLLEYBU\UNIVERSITY VILLAGE\POND\BASIN.PPW ************************************************************************ ************************************************************************ * * * * * MODIFIED RATIONAL METHOD * * ---- Grand Summary For All Storm Frequencies ---- * * * * * ************************************************************************ ************************************************************************ Q = CiA * Units Conversion; Where Conversion = 43560 / (12 * 3600) Area = 1 . 597 cres Tc = 6. 22 , in VOLUMES Freq. Adjusted Duration I Qpeak Allowable Inflow Storage years min in/hr cfs cfs I cu . ft cu.ft 100 .619 18.00 6. 2578 6. 23 6. 15 Ir 1 6732 2266 10 619 14.00 4.8807 4.86 4. 57 4084 1312 2 .619 13 .00 3 .7213 3 .71 3 . 54 2891 851 )\. 1 \Q t\--) -07..vi-J16)\4 PO \l' of ' 4,;:p S/N: E21401D06A89 The Cox Company PondPack Ver . 7. 5 (786c) Compute Time: 11 :43 : 39 Date: 09/12/2005 Type. . . . Master Networlr5ummary Page 1 .02 Name. . . . Watershed File. . . . D: \COXWOOLLEYBU\UNIVERSITY VILLAGE\POND\BASIN.PPW MASTER DESIGN STORM SUMMARY Default Network Design Storm File, ID ALBEMARL . IDQ IDF Storms 10 Rainfall Return Event Type IDF File IDF ID 100yr I-D-F Table STORMS Alb 100yr 10yr I-D-F Table STORMS Alb 10yr 2yr I-D-F Table STORMS Alb 2yr MASTER NETWORK SUMMARY Modified Rational Method Network (*Node=Outfall; +Node=Diversion; ) (Trun= HYG Truncation: Blank=None; L=Left; R=Rt ; LR=Left&Rt) Max Return HYG Vol Qpeak Qpeak Max WSEL Pond Storage Node ID Type Event cu.ft Trun min cfs ft cu .ft *END SECTION JCT 100 3429 18.00 5.75 *END SECTION JCT 10 794 18.00 1 . 91 *END SECTION JCT 2 0 1 .00 .00 MOD.RATIONAL AREA 100 6726 6.22 6. 23 MOD.RATIONAL AREA 10 4079 6.22 4.86 MOD.RATIONAL AREA 2 2887 6.22 3.71 ON-SITE BASININ POND 100 6715 7.00 6. 23 ON-SITE BASININ POND 10 4071 7.00 4. 86 ON-SITE BASININ POND 2 2881 7.00 3 . 71 ON-SITE BASINOUT POND 100 3429 18.00 5. 75 645.47 4175 ON-SITE BASINOUT POND 10 794 18.00 1 . 91 645. 22 3662 ON-SITE BASINOUT POND 2 0 1 .00 .00 644.80 2867 S/N: E21401D06A89 The Cox Company PondPack Ver . 7 . 5 (786c) Compute Time: 11 :43 : 39 Date: 09/12/2005 Type. . . . I-D-F Table Page 2.01 Name. , . . Alb 100yr Tag: 100yr Event: 100 yr File. . . . C: \PROGRA-1\HAESTAD\PPKW\RAINFALL\STORMS . IDF Storm. . . Alb 100yr Tag: 100yr Rainfall-Intensity-Duration Curve Time, min Intens . , in/hr 4.98 9. 5500 10.02 8.0000 15 .00 6.8000 19.98 5.9000 25 .02 5. 3000 30.00 4.7500 34.98 4. 3000 40.02 4.0000 45 .00 3 .7000 49.98 3 . 5500 55 .02 3 . 3000 60.00 3 . 1000 S/N: E21401D06A89 The Cox Company PondPack Ver . 7 . 5 (786c) Compute Time: 11 :43 : 39 Date: 09/12/2005 SINIO Type . . . . I-D-F Table anti Page 2.02 Name . . . . Alb 10yr Tag: 10yr Event : 10 yr File. . . . C : \PROGRA-1\HAESTAD\PPKW\RAINFALL\STORMS . IDF Storm. . . Alb 10yr Tag: 10yr Rainfall-Intensity-Duration Curve Time, min Intens. , in/hr 4.98 7 . 1000 - 10.02 . 1000 -10.02 5.6000 15 .00 4.7000 a, 19.98 4.0500 q,11- 25 .02 ,1'+25 .02 3.6000 30.00 3 . 2000 34.98 2 .9000 40.02 2 . 7000 45 .00 2. 5000 49 .98 2. 3500 55 .02 2. 2000 60.00 2. 1000 S/N: E21401D06A89 The Cox Company PondPack Ver . 7 . 5 (786c) Compute Time: 11 :43: 39 Date: 09/12/2005 Type. . . . I-D-F Table '41•411° V Page 2.03 Name. . . . Alb 2yr Tag: 2yr Event : 2 yr File. . . . C : \PROGRA-1\HAESTAD\PPKW\RAINFALL\STORMS . IDF Storm. . . Alb 2yr Tag: 2yr Rainfall-Intensity-Duration Curve Time, min Intens. , in/hr 4.98 5 . 5000 10.02 4. 2000 15 .00 3 .4000 19.98 2. 9000 % . 25 .02 2 . 5000 30.00 2 . 2000 34.98 2 .0000 40.02 1 .8000 45 .00 1 .7000 49.98 1 .6000 55 .02 1 . 5000 60.00 1 .4000 S/N: E21401D06A89 The Cox Company PondPack Ver . 7 . 5 (786c) Compute Time: 11 :43 : 39 Date: 09/12/2005 r./ Type. . . . Tc Calcs Page 3.01 Name. . . . EXISTING File. . . . D: \COXWOOLLEYBU\UNIVERSITY VILLAGE\POND\BASIN. PPW TIME OF CONCENTRATION CALCULATOR Segment #1 : Tc : User Defined Description : Minimum Segment #1 Time: 5.00 min Total Tc : 5.00 min S/N: E21401D06A89 The Cox Company PondPack Ver . 7. 5 (786c) Compute Time: 11 :43 : 39 Date: 09/12/2005 Type. . . . Tc Calcs %ImI Page 3.03 Name. . . . STR. PIPE ROUTED File. . . . D: \COXWOOLLEYBU\UNIVERSITY VILLAGE\POND\BASIN. PPW Title. . . Pipe TIME OF CONCENTRATION CALCULATOR Pipe Segment #1 : Tc : User Defined Description: Piped Segment #1 rime: 6. 22 min Total Tc : 6. 22 min S/N: E21401D06A89 The Cox Company PondPack Ver . 7 . 5 (786c) Compute Time: 11 :43 : 39 Date: 09/12/2005 u Type. . . . Vol : Elev-Arholle Page 4.01 Name. . . . ON-SITE BASIN File. . . . D: \COXWOOLLEYBU\UNIVERSITY VILLAGE\POND\BASIN.PPW Elevation Planimeter Area Al+A2+sgr(A1*A2) Volume Volume Sum (ft) (sq. in) (sq. ft) (sq.ft) (cu .ft) (cu. ft) 641 . 50 240 0 0 0 642 .00 354 885 148 148 643 .00 751 1621 540 688 644.00 1255 2977 992 1680 645.00 1868 4654 1551 3231 646.00 2462 6475 2158 5390 POND VOLUME EQUATIONS * Incremental volume computed by the Conic Method for Reservoir Volumes . Volume = (1/3) * (EL2-EL1) * (Areal + Area2 + sq. rt . (Areal*Area2) ) where: EL1 , EL2 = Lower and upper elevations of the increment Areal ,Area2 = Areas computed for EL1 , EL2, respectively Volume = Incremental volume between EL1 and EL2 S/N: E21401D06A89 The Cox Company PondPack Ver . 7 . 5 (786c) Compute Time: 11 :43 : 39 Date: 09/12/2005 Type. . . . Diverted Hydrr"faph Page 5.01 Name. . . . CONTROL DEVICE Event : 2 yr File. . . . D: \COXWOOLLEYBU\UNIVERSITY VILLAGE\POND\ Storm. . . Alb 2yr Tag: 2yr DIVERTED HYDROGRAPH . . . HYG file = HYG ID = CONTROL DEVICE HYG Tag = 2yr HYDROGRAPH ORDINATES (cfs) Time I Output Time increment = 1 .00 min min I Time on left represents time for first value in each row. .00 I .00 .00 .00 S/N: E21401D06A89 The Cox Company PondPack Ver . 7 . 5 (786c) Compute Time: 11 :43 : 39 Date: 09/12/2005 Type. . . . Diverted Hydr ' '`raph Page 5.02 Name. . . . CONTROL DEVICE Event : 10 yr File. . . . D: \COXWOOLLEYBU\UNIVERSITY VILLAGE\POND\ Storm. . . Alb 10yr Tag: 10yr DIVERTED HYDROGRAPH. . . HYG file = HYG ID = CONTROL DEVICE HYG Tag = 10yr Peak Discharge = 1 .91 cfs Time to Peak = 18.00 min HYG Volume = 794 cu.ft HYDROGRAPH ORDINATES (cfs) Time Output Time increment = 1 .00 min min Time on left represents time for first value in each row. 14.00 .00 .52 1 .36 1 .81 1 .91 19.00 1 .71 1 .37 .99 .71 .53 24.00 .44 .37 .30 . 25 .20 29.00 . 17 .14 . 11 .09 .07 34.00 .05 .04 .03 .02 .02 39.00 .01 .00 .00 S/N: E21401D06A89 The Cox Company PondPack Ver . 7 . 5 (786c) Compute Time: 11 :43 : 39 Date: 09/12/2005 e Type. . . . Diverted Hydraph Page 5.03 Name. . . . CONTROL DEVICE Event : 100 yr File. . . . D: \COXWOOLLEYBU\UNIVERSITY VILLAGE\POND\ Storm. . . Alb 100yr Tag: 100yr DIVERTED HYDROGRAPH. . . HYG file = HYG ID = CONTROL DEVICE HYG Tag = 100yr Peak Discharge = 5.75 cfs Time to Peak = 18.00 min HYG Volume = 3429 cu .ft HYDROGRAPH ORDINATES (cfs) Time Output Time increment = 1 .00 min min Time on left represents time for first value in each row. 11 .00 .00 . 22 1 .64 3 . 18 4.30 16.00 5 .05 5. 51 5.75 5.70 5 .30 21 .00 4. 67 3 .93 3 . 10 2. 29 1 .54 26.00 1 . 11 .80 . 57 .47 .39 31 .00 . 32 . 27 . 22 . 18 .15 36.00 . 12 . 10 .08 .06 .05 41 .00 .04 .03 .02 .01 .01 46.00 .00 .00 S/N: E21401D06A89 The Cox Company PondPack Ver . 7 . 5 (786c) Compute Time: 11 :43 : 39 Date: 09/12/2005 Type. . . . Pond Infiltra n Calcs Page 5.04 Name. . . . ON-SITE BASIN File. . . . D: \COXWOOLLEYBU\UNIVERSITY VILLAGE\POND\BASIN.PPW INFILTRATION RATING TABLE CALCULATIONS Infilt . (cfs) = ( . 5000 ( in/hr) * Area) * Ku Where: Ku = units conversion factor W. S . Elev Total Area Infilt . ft sq.ft cfs No storage at this elevation. . . infiltration set to zero. 641 . 50 240 .00 641 .60 261 .00 641 .70 283 .00 641 .80 306 .00 641 .90 329 .00 642 .00 354 .00 642.10 387 .00 642.20 422 .00 642 .30 458 .01 642 .40 495 .01 642 . 50 534 .01 642.60 574 .01 642.70 616 .01 642 .80 660 .01 642 .90 705 .01 643 .00 751 .01 643 .10 796 .01 643 . 20 842 .01 643 .30 889 .01 643 .40 937 .01 643 . 50 987 .01 643 .60 1038 .01 643 .70 1090 .01 643 .80 1144 .01 643 .90 1199 .01 644.00 1255 .01 644.10 1311 .02 644.20 1368 .02 644.30 1426 .02 644.40 1486 .02 644. 50 1546 .02 644.60 1608 .02 644.70 1671 .02 644.80 1736 .02 644.90 1801 .02 645.00 1868 .02 645. 10 1924 .02 645.20 1980 .02 645 . 30 2038 .02 645 .40 2096 .02 645. 50 2155 .02 645 .60 2215 .03 S/N: E21401D06A89 The Cox Company PondPack Ver . 7 . 5 (786c) Compute Time: 11 :43 : 39 Date: 09/12/2005 Type. . . . Pond Infiltran Calcs Page 5.05 Name. . . . ON-SITE BASIN File. . . . D: \COXWOOLLEYBU\UNIVERSITY VILLAGE\POND\BASIN. PPW INFILTRATION RATING TABLE CALCULATIONS Infilt . (cfs) = ( . 5000 (in/hr) * Area) * Ku Where: Ku = units conversion factor W. S. Elev Total Area Infilt . ft sq. ft cfs 645 .70 2275 .03 645 .80 2337 .03 645 .90 2399 .03 646.00 2462 .03 S/N: E21401D06A89 The Cox Company PondPack Ver . 7 . 5 (786c) Compute Time: 11 :43 : 39 Date: 09/12/2005 Type. . . . Mod. Rationale'faph Page 6.01 Name. . . . MOD.RATIONAL Tag: 2yr Event : 2 yr File. . . . D: \COXWOOLLEYBU\UNIVERSITY VILLAGE\POND\BASIN. PPW Storm. . . Alb 2yr Tag: 2yr MODIFIED RATIONAL METHOD ---- Graphical Summary for Maximum Required Storage ---- Method I Q = CiA * Units Conversion; Where Conversion = 43560 / (12 * 3600) ********************************************************************** * RETURN FREQUENCY: 2 yr 1 Allowable Outflow: 3 . 54 cfs * 'C' Adjustment : 1 .000 1 Required Storage: 851 cu .ft * * * Peak Inflow: 3 .71 cfs * .HYG File: 2yr ********************************************************************** Q I Td = 13 .00 min I Return Freq: 2 yr / Approx. Duration for Max. Storage / C adj . factor : 1 .000 Tc= 6. 22 min I = 5 . 1802 in/hr Area = 1 . 597 acres . Q = 5. 16 cfs Weighted C = .619 . 1 . Adjusted C = .619 • 1 • • I • Required Storage . -- 851 cu .ft Td= 13 .00 min • I I I = 3 .7213 in/hr x x x x x x xlx x x x x x x x x x x Q = 3 .71 cfs 1 x x o Q = 3. 54 cfs x o x (Allow.Outflow) . x o . x o NOT TO SCALE x . x o x 13 . 28 min T S/N: E21401D06A89 The Cox Company PondPack Ver . 7 . 5 (786c) Compute Time: 11 :43 : 39 Date: 09/12/2005 HydNgfaph ON-SITE BASININ 3- 2- Plotted Curves o ----- - CONTROL DEVICE 2yr u_ - ON-SITE BASININ 2yr 1_ 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Time (min) Type. . . . Mod. RationalZtorm Calcs Page 6.02 Name. . . . MOD.RATIONAL Tag: 2yr Event : 2 yr File. . . . D: \COXWOOLLEYBU\UNIVERSITY VILLAGE\POND\BASIN.PPW Storm. . . Alb 2yr Tag: 2yr MODIFIED RATIONAL METHOD ---- Summary for Single Storm Frequency ---- Q = CiA * Units Conversion; Where Conversion = 43560 / (12 * 3600) RETURN FREQUENCY: 2 yr 'C ' Adjustment = 1 .000Allowablq = 3 . 54 cfs Hydrograph Storm Duration , Td = 13.00 min Tc = 6. 22 min Hydrograph File: 2yr VOLUMES Wtd. Adjusted Duration Intens . Area Qpeak 1 Inflow Storage 'C ' 'C ' min in/hr acres cfs 1 cu . ft cu.ft I .619 .619 6. 22 5 .1802 1 . 597 5 . 16 1 1926 605 .619 .619 10.00 4.2052 1 . 597 4. 19 1 2513 791 ************************************************************ Storage Maximum .619 .619 13 .00 3 .7213 1 . 597 3.71 I 2891 851 **************************************************************************** .619 .619 15.00 3 .4000 1 . 597 3 . 39 1 Qpeak < Qallow S/N: E21401D06A89 The Cox Company PondPack Ver . 7 . 5 (786c) Compute Time: 11 :43 : 39 Date: 09/12/2005 Type. . . . Mod. Rationalaph Page 6. 03 Name. . . . MOD.RATIONAL Tag: 10yr Event : 10 yr File. . . . D: \COXWOOLLEYBU\UNIVERSITY VILLAGE\POND\BASIN. PPW Storm. . . Alb 10yr Tag: 10yr MODIFIED RATIONAL METHOD ---- Graphical Summary for Maximum Required Storage ---- Method I Q = CiA * Units Conversion; Where Conversion = 43560 / (12 * 3600) ********************************************************************** * RETURN FREQUENCY: 10 yr I Allowable Outflow: 4. 57 cfs * 'C ' Adjustment : 1.000 I Required Storage: 1312 cu. ft * * * Peak Inflow: 4.86 cfs * .HYG File: 10yr ********************************************************************** Q I Td = 14.00 min I Return Freq: 10 yr Approx. Duration for Max. Storage / C adj .factor : 1 .000 Tc= 6. 22 min I = 6.7310 in/hr Area = 1 . 597 acres . Q = 6.70 cfs Weighted C = .619 . I . Adjusted C = .619 • 1 • • 1 • Required Storage . -- 1312 cu.ft Td= 14.00 min • 1 • I I = 4.8807 in/hr x x x x x x xlx x x x x x x x x x x Q = 4.86 cfs • 1 x x o Q = 4. 57 cfs . x o x (Allow.Outflow) . x o . x o NOT TO SCALE x . x o x 14. 37 min T S/N: E21401D06A89 The Cox Company PondPack Ver . 7. 5 (786c) Compute Time: 11 :43 : 39 Date: 09/12/2005 j Hydro' `ph ON-SITE BASININ 4 3 co Plotted Curves o CONTROL DEVICE l0yr u 2- ON-SITE BASININ 10yr 1- / i \\\\\ _./ / \,\ -..,,,,,,,,........ 0 10 20 30 40 Time (min) Type. . . . Mod. RationalSorkorm Calcs Page 6.04 Name. . . . MOD.RATIONAL Tag: 10yr Event : 10 yr File. . . . D: \COXWOOLLEYBU\UNIVERSITY VILLAGE\POND\BASIN.PPW Storm. . . Alb 10yr Tag: 10yr MODIFIED RATIONAL METHOD ---- Summary for Single Storm Frequency ---- Q = CiA * Units Conversion; Where Conversion = 43560 / (12 * 3600) RETURN FREQUENCY: 10 yr 'C ' Adjustment = 1 .000Allowable Q = 4. 57 cfs Hydrograph Storm Duration, Td = 14.00 min Tc = 6. 22 min Hydrograph File: 10yr VOLUMES Wtd. Adjusted Duration Intens. Area Qpeak I Inflow Storage 'C ' 'C ' min in/hr acres cfs I cu .ft cu . ft .619 .619 6. 22 6.7310 1 . 597 6.70 I 2502 797 .619 .619 10.00 5 .6060 1 . 597 5 . 58 I 3351 1127 ************************************************************ Storage Maximum .619 .619 14.00 4.8807 1 . 597 4.86 I 4084 1312 **************************************************************************** .619 .619 15 .00 4.7000 1 . 597 4.68 I 4214 1305 .619 .619 20.00 4.0482 1 . 597 4.03 I Qpeak < Qallow S/N: E214O1DO6A89 The Cox Company PondPack Ver . 7 . 5 (786c) Compute Time: 11 :43 : 39 Date: 09/12/2005 `rIr Type. . . . Mod. Rational4000-aph Page 6.05 Name. . . . MOD.RATIONAL Tag: 100yr Event: 100 yr File. . . . D: \COXWOOLLEYBU\UNIVERSITY VILLAGE\POND\BASIN. PPW Storm. . . Alb 100yr Tag: 100yr MODIFIED RATIONAL METHOD ---- Graphical Summary for Maximum Required Storage ---- Method I Q = CiA * Units Conversion; Where Conversion = 43560 / (12 * 3600) ********************************************************************** * RETURN FREQUENCY: 100 yr I Allowable Outflow: 6. 15 cfs * 'C ' Adjustment : 1 .000 1 Required Storage: 2266 cu. ft * * * Peak Inflow: 6. 23 cfs * * . HYG File: 100yr * ********************************************************************** Q I Td = 18.00 min I Return Freq: 100 yr Approx. Duration for Max. Storage / C adj .factor : 1 .000 Tc= 6. 22 min I = 9. 1687 in/hr Area = 1 . 597 acres . Q = 9.13 cfs Weighted C = .619 . I . Adjusted C = . 619 • I • Required Storage . -- 2266 cu.ft Td= 18.00 min • I • I I = 6. 2578 in/hr x x x x x x x I x x x x x x x x x x x Q = 6. 23 cfs x x o Q = 6. 15 cfs x o x (Allow.Outflow) . x o • x o . NOT TO SCALE x . x • x 18.09 min T S/N: E21401D06A89 The Cox Company PondPack Ver . 7. 5 (786c) Compute Time: 11:43 : 39 Date: 09/12/2005 s • Hyd roph — ON-SITE BASININ 6- 5- 4- Plotted Curves ..._ _ , '1, \\ _ CONTROL DEVICE 100yr 3 ON-SITE BASININ 100yr 2- _ / \1- 0 10 20 30 40 Time (min) r • Type. . . . Mod. RationaNwO orm Calcs `411•01 Page 6.06 Name. . . . MOD.RATIONAL Tag: 100yr Event: 100 yr File. . . . D: \COXWOOLLEYBU\UNIVERSITY VILLAGE\POND\BASIN.PPW Storm. . . Alb 100yr Tag: 100yr MODIFIED RATIONAL METHOD ---- Summary for Single Storm Frequency ---- Q = CiA * Units Conversion; Where Conversion = 43560 / (12 * 3600) RETURN FREQUENCY: 100 yr 'C ' Adjustment = 1 .000Allowable Q = 6. 15 cfs Hydrograph Storm Duration , Td = 18.00 min Tc = 6. 22 min Hydrograph File: 100yr VOLUMES Wtd. Adjusted Duration Intens . Area Qpeak Inflow Storage 'C ' 'C ' min in/hr acres cfs cu.ft cu.ft .619 .619 6. 22 9. 1687 1 . 597 9. 13 3409 1114 .619 .619 10.00 8.0062 1 . 597 7. 98 4785 1794 . 619 .619 15.00 6.8000 1 . 597 6.77 6096 2183 ************************************************************ Storage Maximum .619 .619 18.00 6. 2578 1 . 597 6. 23 1 6732 2266 **************************************************************************** .619 .619 20.00 5.8976 1 . 597 5.87 1 Qpeak < Qallow S/N: E21401D06A89 The Cox Company PondPack Ver . 7. 5 (786c) Compute Time: 11 :43 : 39 Date: 09/12/2005 c • Type. . . . C and Area v Page e 6.07 Name. . . . PROP. RATIONAL File. . . . D: \COXWOOLLEYBU\UNIVERSITY VILLAGE\POND\BASIN.PPW Title. . . Proposed Conditions RATIONAL C COEFFICIENT DATA Proposed Conditions�i' (-1;‘/L'CI Area C x Area Soil/Surface Description C acres acres Drop Inlet 2 . 7500 . 132 .099 ✓ Drop Inlet 3 .6100 .830 . 506✓ Drop Inlet 4 .8400 .076 .064 ✓ Drop Inlet 5 .4500 .044 . 020 ,✓ Drop Inlet 6 .7000 . 310 . 2171✓ Surface Drainage .4000 . 205 . 082 ;/ WEIGHTED C & TOTAL AREA ---> .6186 1 . 597 . 988 S/N: E21401D06A89 The Cox Company PondPack Ver . 7 . 5 (786c) Compute Time: 11 :43 : 39 Date: 09/12/2005 4 0 Appendix A `44100" A-1 Index of Starting Page Numbers for ID Names A Alb 100yr 100yr . . . 2 .01 Alb 10yr 10yr . . . 2 .02 Alb 2yr 2yr . . . 2.03 , 5.01 , 5 .02, 5 .03 E EXISTING. . . 3 .01 , 6. 01 , 6.02, 6.03 , 6.04, 6.05, 6.06 0 ON-SITE BASIN. . . 4.01 , 5.04 P PROP. RATIONAL. . . 6.07 S STR. PIPE ROUTED. . . 3 .03 W Watershed. . . 1 .01 , 1 .02 S/N: E21401D06A89 The Cox Company PondPack Ver . 7. 5 (786c) Compute Time: 11 :43 : 39 Date: 09/12/2005