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WPO200500007 Calculations Stormwater Management Plan 2005-09-21
STORMWATER MANAGEMENT CALCULATIONS FOR FACILITY A WESTHALL PHASE I & II ( w submittal Prepared by: Reviewed and Approved by the Community Development Department Date: 9- 2/ - o 5 File#: W a Zo S coo W A idENGINEERS SURVEYORS PLANNERS ASSOCIATES 147 Mill Ridge Road 1402 Greenbrier Place Lyncimasg,VA 24502 Cb*kdtesrine,VA 22901 More:434-562-6175 Mar 434-9E4-2700 wAr4rrwirerefillter.ne t R �4 l I 1 ('.August 23, 2005 (Revised) k fr ,2�- o DAVID M. JENSE v Project Number: 204208.03 No. 1 484 �A i 2 eA SS1ONAl, 1-4• G Stormwater Management Calculations WWA No. 204208.03 Table of Contents Stormwater Management Tab A: Stormwater Narrative Figure 1 Figure 2 Stormwater Computations Tab B: Routing: Facility A Modified Rational Method Tab C: Routing: Facility A Iteration 1 (Td=20 min) Tab D: Routing: Facility A Iteration 2 (Td=24 min) Tab E: Routing: Facility A Rational Method AUG 25 2005 COMMUNITY DEvizi .,i-mi._ofI 1 Stormwater Management Calculations WWA No. 204208.03 Stormwater Narrative The site for Westhall Phase I and II is located approximately one mile southeast of Crozet,Virginia. The site is situated on a slight ridge that ultimately drains to Lickinghole Creek. The predominant land cover on the western area of the site is pasture in good condition. The eastern edge of the site along the Lickinghole Creek floodplain is wooded. Some offsite drainage flows onto the site from a mobile home park located north of Park Street. Planned stormwater management facilities for Westhall Phase I and II include provisions for quantity control. Stormwater quality control will be achieved through the existing Lickhinghole Basin, an Albemarle County regional stormwater management facility. Quantity controls include Facility A, an extended detention basin. The pre-development drainage area for Facility A is 5.9 acres. The post-development drainage area will increase to 8.43 acres due to a 2.53 acre area that will be routed to the facility via a permanent berm feature. In order to protect downstream properties and existing stormwater structures, Facility A was designed to attenuate the 1-year, 2-year and 10-year 24-hour rainfall events while safely conveying the 100-year 24-hour event. The pre-development 1-year, 2-year and 10-year peak flow rates for Facility A were found to be 6.4, 6.8 cfs and 9.4 cfs respectively. Facility A will attenuate the post-development 1-year, 2-year and 10-year peak flow rates to 6.06, 6.36 cfs and 9.33 cfs respectively. The facility will provide adequate freeboard to safely convey the 100-year storm event by means of the primary outlet structure with a maximum water surface elevation of 635.22 ft. Facilites A was routed using Hydraflow Hydrographs 2004 software by Intelisolve. The Modified Rational Method was utilized to find the trapezoidal-shaped inflow hydrograph that produced the peak volume required in each facility. This was done by iterating the storm duration (Td)until the hydrograph with the maximum volume was found. During the iterations,the release rate was held approximately constant near the allowable release rate. Once found, the peak volume hydrograph was used for routing and outlet structure design for the facility. In addition to routing peak volume hydrographs with the Modified Rational Method, triangular peak flow hydrographs were routed using the Rational Method. These triangular hydrographs were used to check the release rates and riser structure design. 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I f�` / Iii ... . r 1 / \l.-i\�`\ \ \ ?YES \\./ I^-m•�- _�`\`� J/ Q %� / / 1. ,°„- \\` \ , IF H D 0 IS A, REDUCTION +I �,.` / \ \ `�_-`- At1P7y / GL USILBF_.-US-1\( da PROJECT:. ow ((ENSIGN toweEk WEST HALL PHASE I&H PRE—DEVELOPED �""""' STONEHAIUSDEVELOPMEHPG �a S.avcxres EL nan PATh CONDITIONS ASSOCIATES „ m PRE-DEVELOPED HYDROLOGY CONDITIONS Figure I - w0420 3 r uscwne SCSI: SATE: m,.OF I NO. xssmx Sr art w irzwaw ex arc — 2V420AP1 �'° CP& Y me 12-28-04 1 OF 1 e cf FACIL-i,TY r FJ y l i11 1 ii / } I DA 6'4 AC -- _ ,.... y, t + \11\ /� /� J ICI .N^ __ ',`.� t S-L..I,: rrI Jr i,) 1 i i /../ , , , iQ/j^]/I1- �"J "y.,�..v�,� J f _ 1 t �,'(`.ll. L �r. /—i ' / I , j. - p L( {'V l:IE/ 0 \1=� 's. LEGEND �rrt , / // '1 I I y \ �.r . 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' I / l 11 j r b1111 11h t/ 1 1 I IT'1.6f y �.//l / 3 I I I l/ / / //ill 11lR III I \ I: { 1 1� -... , r 1 1 y I i ,f .� / ,--An---,f •' i,+/J'/'d 1 1,111 1 ST ..W• IfYPIPEe/r..• / / 1 � �/ i5 1 r . -''f , / yi' �/;/ ,I1 ryc(p1• `� \ x \ �i 1-'r ,��/ _ t__L3t � / I �� N'Y / j. + y'�. � ,� l�r�- /< Y i��'i ��l ( \ i r I / .-,_»___ ,!-i c,rpo\_, / / / \�; \ l 1 1/lam%i• <- //�' ///' 4 PHASE IV I (1 � I l i 1'- / :� 1 I i I / .. �+\ \ \� / „r, / / // // P E III -+--� / As. \ / [ � ._-.� a -u , `.; ` II A -r--- ✓ ' L -h--\ �r \ � j L ___� A 1 j ' (,,,yyy{ —l1I I :. / ..� l ^ rr<, rr-S��! / / `gc, • : ` 4 t + I I C 'd^✓ r ,' /^r,�=.r- —._ �---1--_ ` ,,, ,\ ��y., i� i / i i ,O• + '+\\{ It�'ti{I \t`i�"` �.Siil4 I Y / i. r'�j rr-'- ', �\ ig- 7 J-Fr / �,:/ 1- C1 \H{,,, 11111yy i\il\ �1\ 4 T I u < r �, '„� --4v - r 1J z (.`2' I\I IIi1,11'Ili ill tolx \ 1s o A ifill it 1111114 11 \` ran C ., 1• �G' 1' +r-j ._Jt ??'• , 1 �,b. •,r` (( l riun from _I �'1 �C\ 4 � ' .+�� ��,s - J r/• �'��/�j / J/ �� � - ��i�''�``_ f.✓�,e ,..au . .c.7., _.....3 \\ .") Cil `I % "�,rt / ` `• �'-rV �...: 1/i 3 i f 3;- Y j( yr �_\ ,\ \ _" Cf-i ll\ �l ID/' \ •\ Ill £l / /i/ �! t' -1//// / ! J C`i'7 1?,.j: 1 \ - -----r-----------, •\ /_ A itc.,\\'"r'rfe. 7/4' :"-- - / I / i ,„„--- 4 DA � sic- f \ n-n-cr; r``J c-k f J, _,=-- y`,/,/ I RINSED PPR WW1, TS EPA e.ommus tom PINS."...PA emvcr. WEST HALL PHASE!THROW R envm )— smNE1NUSOEVELOPMENi ax r.wn a ma+ucr PRO IRMZED R: /epv POST-DEVELOPED MUM CONDITIONS POSI'-fICN!LOPED IIYDROLOOY CONDITIONS Figure ZR 12-18-04 I OF f NO. PENSION Or air( w. PnTS"N e. n.rt �^ awaoaw ��*� �.p erm� v lax Stormwater Management Calculations DMA No.204208.03 Facility A Drainage Area Pre-Development= 5.9 ac Post-Development= 5.9 ac + 2.53 ac= 8.43 ac Ground Cover and C-Factor Pre-development: Pavement=0.12 ac C=0.90 Roof=0.17 ac C=0.90 Forest: C=0.30 onsite=0.30 ac offsite=0.12 ac Gravel=0.30 ac C=0.90 Lawns: C =0.20 onsite= 1.35 ac offsite=0.12 ac Pasture= 1.85 ac C=0.45 Cpre= (0.29ac)(0.9)+(0.42ac)(0.30)+(0.30ac)(0.90)+(3.04ac)(0.20)+(1.85ac)(0.45) 5.9ac Cpre=0.36 Post-development: Pavement=0.87 ac C=0.90 Offsite Area(Zone R4)= 1.81 ac C=0.50 6,000 sf lots=3.14 ac C=0.50 Townhouses= 1.34 ac C= 0.65 Open Space=0.84 ac C=0.30 Cpost = (0.87ac)(0.90)+(1.81ac)(0.50)+(3.14ac)(0.50)+(1.34ac)(0.65)+(0.84ac)(0.30) 8.43ac Cpost=0.51 Time of Concentration (Please reference Figures 1 and 2 for Tc flow paths) Pre-development(two parts): 1) Seelye Method for Overland Flow (A-4 C) Tcr=0.225L°42S o.i9C-t.o L=200 ft S =0.035 C=0.30 Tc1= 13.1 min 3 Stotmwater Management Calculations WWA No. 204208.03 2) Kirpich Method for Shallow Concentrated Flow (C-*D F) Tc2=0.000948H-038L1.13 H=660 ft—631 ft=29 ft L=620ft Tc2=3.8 min tc= To + Tc2= 16.9 min (Pre-Developed) Post-Developed(three parts): 1) Seelye Method for Overland Flow (A->B) To=0.225Lo.42S o.19C1.0 L= 100ft S =0.035 C=0.50 Tc=5.9min 2) Kirpich Method for Shallow Concentrated Flow (B -*D) Tc2=0.009481I4138L1.13 H=665 ft-642ft=23 ft L=540ft Tc2=3.5min 3) Conduit Flow (D —>E -*F) L Tc3 = V V=4 fps or240ftlmin L=290 ft(closed conduit) Tm= 1.21min t,= To + Tc2+ Tc3=10.6 min (Post-Developed) Intensity(VSMH Appendix 4D—Albemarle County IDF) 1 yr(tc= 16.9 min): I1=3.0 in/hr(Albemarle Co. IDF Curves GEB 7Jul2005) 2 yr(tc= 16.9 min): I2=3.2 in/hr 10 yr(te= 16.9 min): Ito=4.4 in/hr 100 yr(tc= 16.9 min): Ito=6.4 in/hr Rational Method Q=CIA(Allowable Discharge) 1 yr: QI =(0.36)(3.0 in/hr)(5.9ac.) =6.4 cfs 2 yr: Q2=(0.36)(3.2 in/hr)(5.9ac.) =6.8 cfs 10 yr: Qio=(0.36)(4.4 in/hr)(5.9 ac.)=9.4 cfs 100 yr:Q10o= (0.36)(6.4 in/hr)(5.9 ac.)= 13.6 cfs 4 Stormwater Management Calculations WWA No.204208.03 Modified Rational Direct Solution (VSMH p. 5-23) 1) Define 2-year critical storm duration. T — I2CAa(b—t 14) —b d2 — 402 C=0.51 A= 8.43 ac tc= 10.6 min q02=6.8cfs a2= 106.02 b2= 15.51 2(0.51)(8.43)(106.02)(15.51- 10.6) Td2 =1 4 —15.51=26.0min 6.8 2. Solve for the 2-yr critical storm intensity, I2. I = a = 106.02 =2.55in/hr 2 b+Td2 15.51+26.0 3. Determine 2-yr peak inflow. Qi2 = Cl2A=(0.57)(2.55in/hr)(8.43ac) =12.3cfs 4. Determine the 2 yr required storage volume. i V2 = Q12Td2 + Qnte — 9o2Td2 — 39o2tc 60 [ 4 2 4 Q12= 12.3 cfs C =0.51 A= 8.43 ac Td2=26.0 min tc= 10.6min qo2=6.8 cfs (12.3)410.6) — (6.8)(26.0) — (3)(6. )(10.6)160 V2 =[02.3)(26.o)+ k212596 f 5. Determine 10-year Ta10 C=0.51 A= 8.43ac tc= 10.6min go10=9.4 cfs a10= 161.60 b10= 18.73 5 Stotmwater Management Calculations WWA No.204208.03 (0.51)(8.43)(161.60)(18.73— 10.6)(2) Ta10 9.4 4 —18.73 =30.0 min 6. Solve for 110 1 = ato = 161.60 =3.32in 1 hr 10 b10 +Taro 18.73+30.0min 7. Solve for Qio Qio=CI10A=(0.57)(3.32 in/hr)(8.43ac) = 16.0 cfs 8. Solve for V10 Yio = Qi1oTdlo + Qaot� —9otoTato _ 39o1oto 60 4 2 4 Quo= 16.0 cfs C =0.51 A=8.43 ac Tdlo=30.0 min te= 10.6min Qom=9.4 cfs Y10 =[(16.o)(30.omin)+ (16.0 (10.6) — (9.4)(30.0) — (3)(9.�(10.6)160 V10=21,100 cf J Facility A Routing Summary The post-development peak discharges for the 1-year,2-year and 10-year storms are less than the pre-development discharges, therefore Facility A meets requirements. Qipost(6.06 cfs) <Q2pre(6.4 cfs) Q2post(6.36 cfs) <Q2pre(6.8 cfs) Qiopost (9.33 cfs) <Qiopre (9.4 cfs) 6 Stotmwatet Management Calculations WWA No.204208.03 ROUTING SUMMARIES Modified Rational Method (Trapezoidal Inflow Hydrographs): Design(Td=22 min) 1-Year Storm: Q2=6.06 cfs T,= 11 min Td=22 min Maximum Storage=7,711 cf Peak Elevation=633.72 2-Year Storm: Q2=6.36cfs T,= 11min Td=22 min Maximum Storage= 8,709 cf Peak Elevation=634.03 10-Year Storm: Qio=9.33 cfs T,= 11 min Td=22 min Maximum Storage= 12,057 cf Peak Elevation=634.84 100-Year Storm: Qloo=21.88 cfs Tc= 11 min Td=22 min Maximum Storage= 13,908 cf Peak Elevation=635.22 Iteration 1 (Td=20 min) 1-Year Storm: Q2=5.91 cfs Tc= 11 min Td=20 min Maximum Storage=7,262 cf Peak Elevation=633.58 2-Year Storm: Q2 = 6.21 cfs T,=11 min Td=20 min Maximum Storage=8,197 cf 7 Stormwater Management Calculations WWA No.204208.03 Peak Elevation= 633.88 10-Year Storm: Qio=7.71 cfs Te= 11 min Td=20 min Maximum Storage= 1,474cf Peak Elevation=634.69 100-Year Storm: Qioo= 17.48 cfs Te= 11 min Td=20min Maximum Storage= 13,632 cf Peak Elevation=635.17 Iteration 2 (Td=24 min) 1-Year Storm: Q2=5.99 cfs Te= 11 min Td=24 min Maximum Storage=7,497 of Peak Elevation=633.65 2-Year Storm: Q2=6.28 cfs Te= 11 min Td=24 min Maximum Storage=8,471 cf Peak Elevation=633.96 10-Year Storm: Qio= 8.69 cfs 'Fe= 11 min Td=24 min Maximum Storage= 11,920 cf Peak Elevation=634.80 100-Year Storm: Qioo= 18.52 cfs Te= 11 min Td=24 min Maximum Storage= 13,828 cf Peak Elevation=635.20 8 Stotmwater Management Calculations WWA No.204208.03 Rational Method (Triangular Inflow Hydrographs): 1-Year Storm: Q2=5.58cfs Tc= 11 min Maximum Storage=6,218 cf Peak Elevation=633.25 2-Year Storm: Q2=5.81 cfs Tc= 11 min Maximum Storage= 6,951 of Peak Elevation=633.48 10-Year Storm: Qio=6.67 cfs Tc= 11min Maximum Storage=9,531 cf Peak Elevation=634.23 100-Year Storm: Qioo= 11.58 cfs Tc= 11 min Maximum Storage= 12,502 cf Peak Elevation=634.94 9 Table of Contents WesthallA-1YR gpw Hydraflow Hydrographs by Intelisolve Wednesday,Aug 24 2005, 12:32 PM Hydrograph Return Period Recap 1 1 - Year Summary Report 2 Hydrograph Reports 3 Hydrograph No. 2, Reservoir, Facility A 3 Pond Report 4 2 - Year Summary Report 5 Hydrograph Reports 6 Hydrograph No. 2, Reservoir, Facility A 6 Pond Report 7 10 - Year Summary Report 8 Hydrograph Reports 9 Hydrograph No. 2, Reservoir, Facility A 9 Pond Report 10 100 - Year Summary Report 11 Hydrograph Reports 12 Hydrograph No. 2, Reservoir, Facility A 12 Pond Report 13 1 Hydrograph Return Period Recap Hyd. Hydrograph Inflow Peak Outflow(cfs) Hydrograph No. type Hyd(s) description (origin) 1-Yr 2-Yr 3-Yr 5-Yr 10-Yr 25-Yr 50-Yr 100-Yr 1 Mod.Rational — 11.31 12.39 — — 16.27 — — 21.88 Westhall A 2 Reservoir 1 6.06 6.36 — — 9.33 — — 18.96 Facility A Proj. file: Westhall A-1YR.gpw Wednesday, Aug 24 2005, 12:32 PM Hvdraflnw Hvdrnnnanhc by Infnlicnlvc 2 Hydrograph Summary Report Hyd. Hydrograph Peak Time Time to Volume Inflow Maximum Maximum Hydrograph No. type flow interval peak hyd(s) elevation storage description (origin) (cfs) (min) (min) (cuft) (ft) (cuft) 1 Mod.Rational 11.31 1 11 14,934 — — — Westhall A 2 Reservoir 6.06 1 27 14,931 1 633.72 7,711 FacilityA i Westhall A-1YR.gpw Return Period: 1 Year Wednesday, Aug 24 2005, 12:32 PM Hydraflow Hydrographs by Intelisolve Hydrograph Plot 3 Hydratlow Hydrographs by Intelisolve Wednesday,Aug 24 2005, 12:32 PM Hyd. No. 2 Facility A Hydrograph type = Reservoir Peak discharge = 6.06 cfs Storm frequency = 1 yrs Time interval = 1 min ' Inflow hyd. No. = 1 Max. Elevation = 633.72 ft Reservoir name = Facility A Max. Storage = 7,711 cuft Storage Indication method used. Hydrograph Volume=14,931 cuft Facility A Q(cfs) Hyd. No.2— 1 Yr Q (cfs) 12.00 12.00 ' 10.00 10.00 8.00 8.00 6.00 6.00 4.00 4.00 2.00 2.00 0.00 0.00 0.0 0.2 0.3 0.5 0.7 0.8 1.0 1.2 1.3 1.5 1.7 Time (hrs) — Hyd No. 2 — Hyd No. 1 Pond Report 4 Hydraflow Hydrographs by Intelisoive Wednesday,Aug 24 2005,12:32 PM Pond No. 1 - Facility A Pond Data Pond storage is based on known contour areas.Average end area method used. Stage/Storage Table -- Stage(ft) Elevation(ft) Contour area(sqft) Incr.Storage(cuft) Total storage(cuft) 0.00 630.00 1,100 0 0 1.00 631.00 1,535 1,318 1,318 2.00 632.00 1,970 1,753 3,070 3.00 633.00 2,760 2,365 5,435 4.00 634.00 3,550 3,155 8,590 5.00 635.00 4,750 4,150 12,740 6.00 636.00 5,950 5,350 18,090 Culvert/Orifice Structures Weir Structures [A] [B] [C] [D] [A] [B] [C] [D] Rise(in) = 24.00 12.00 0.00 0.00 Crest Len(ft) = 9.42 0.50 0.00 0.00 Span(in) = 24.00 12.00 0.00 0.00 Crest El.(ft) = 634.70 634.00 0.00 0.00 No.Barrels = 1 1 0 0 Weir Coeff. = 3.33 3.33 0.00 0.00 Invert El.(ft) = 629.80 630.00 0.00 0.00 Weir Type = Riser Rect - - Length(ft) = 41.50 0.00 0.00 0.00 Multi-Stage = Yes Yes No No Slope(%) = 0.83 0.00 0.00 0.00 N-Value = .026 .026 .013 .000 Orif.Coeff. = 0.80 0.60 0.60 0.00 Multi-Stage = Na Yes No No Exfiltratlon= 0.000 in/hr(Contour) Tailwater Elev.= 0.00 ft Note:Culvert/Odfce outflows have been analyzed under Inlet and outlet control. Welr riser checked for orifice conditions. Stage(ft) Stage/Discharge Stage(ft) 6.00 6.00 • _ _ 5.00 5.00 4.00 4.00 3.00 3.00 2.00 2.00 1.00 1.00 0.00 0.00 0.00 3.00 6.00 9.00 12.00 15.00 18.00 21.00 24.00 27.00 30.00 - Total Q Discharge(cfs) 5 _ Hydrograph Summary Report Hyd. Hydrograph Peak Time Time to Volume Inflow Maximum Maximum Hydrograph No. type flow interval peak hyd(s) elevation storage description (origin) (cfs) (min) (min) (cuft) (ft) (cuft) 1 Mod.Rational 12.39 1 11 16,350 -- Westhall A 2 Reservoir 6.36 1 27 16,347 1 634.03 8,709 FacilityA • Westhall A-1YR.gpw Return Period: 2 Year Wednesday, Aug 24 2005, 12:32 PM Hydraflow Hydrographs by Intelisolve Hydrograph Plot 6 Hydraflow Hydrographs by Intelisolve Wednesday,Aug 24 2005,12:32 PM Hyd. No. 2 Facility A Hydrograph type = Reservoir Peak discharge = 6.36 cfs Storm frequency = 2 yrs Time interval = 1 min Inflow hyd. No. = 1 Max. Elevation = 634.03 ft Reservoir name = Facility A Max. Storage = 8,709 cuft ' Storage Indication method used. Hydrograph Volume=16,347 cuft Facility A Q (cfs) Q(cfs) Hyd. No.2—2 Yr 14.00 14.00 12.00 12.00 10.00 10.00 8.00 8.00 6.00 6.00 4.00 4.00 2.00 - 2.00 0.00 — 0.00 0.0 0.2 0.3 0.5 0.7 0.8 1.0 1.2 1.3 1.5 1.7 Time (hrs) — Hyd No. 2 — Hyd No. 1 Pond Report 7 - Hydraflow Hydrographs by Intelisolve Wednesday,Aug 24 2005, 12:32 PM Pond No. 1 - Facility A Pond Data Pond storage is based on known contour areas.Average end area method used. Stage/Storage Table Stage(ft) Elevation(ft) Contour area(sqft) Incr.Storage(cuft) Total storage(cuft) 0.00 630.00 1,100 0 0 1.00 631.00 1,535 1,318 1,318 2.00 632.00 1,970 1,753 3,070 3.00 633.00 2,760 2,365 5,435 4.00 634.00 3,550 3,155 8,590 -- 5.00 635.00 4,750 4,150 12,740 6.00 636.00 5,950 5,350 18,090 Culvert/Orifice Structures Weir Structures [A] [B] [C] [D] [A] [B] [C] [D] Rise(in) = 24.00 12.00 0.00 0.00 Crest Len(ft) = 9.42 0.50 0.00 0.00 -- Span(in) = 24.00 12.00 0.00 0.00 Crest El.(ft) = 634.70 634.00 0.00 0.00 __ No.Barrels = 1 1 0 0 Weir Coeff. = 3.33 3.33 0.00 0.00 Invert El.(ft) = 629.80 630.00 0.00 0.00 Welr Type = Riser Rect - -- Length(ft) = 41.50 0.00 0.00 0.00 Multi-Stage = Yes Yes No No Slope(%) = 0.83 0.00 0.00 0.00 - N-Value = .026 .026 .013 .000 • Orif.Coeff. = 0.80 0.60 0.60 0.00 Multi-Stage = n/a Yes No No Exfiltration= 0.000 in/hr(Contour) Tailwater Elev.= 0.00 ft Note:Culvert/Onfce outflows have been analyzed under Inlet and outlet control. Welr riser checked for orifice conditions. Stage(ft) Stage/Discharge Stage(ft) _I 6.00 6.00 4.00 4.00 3.00 _.-.- 3.00 2.00 2.00 1.00 1.00 0.00 0.00 0.00 3.00 6.00 9.00 12.00 15.00 18.00 21.00 24.00 27.00 30.00 Total O Discharge(cfs) 8 _ Hydrograph Summary Report Hyd. Hydrograph Peak Time Time to Volume Inflow Maximum Maximum Hydrograph No. type flow interval peak hyd(s) elevation storage description (origin) (cfs)' (min) (min) (cuft) (ft) - (cuff) 1 Mod.Rational 16.27 1 11 21,481 .- --- Westhall A 2 Reservoir 9.33 1 27 21,479 1 634.84 12,057 FacilityA --i Westhall A-1YR.gpw Return Period: 10 Year Wednesday, Aug 24 2005, 12:32 PM Hydraflow Hydrographs by Intelisolve 9 Hydrograph Plot Hydraflow Hydrographs by Intelisolve Wednesday,Aug 24 2005, 12:32 PM Hyd. No. 2 Facility A Hydrograph type = Reservoir Peak discharge = 9.33 cfs Storm frequency = 10 yrs Time interval = 1 min Inflow hyd. No. = 1 Max. Elevation = 634.84 ft Reservoir name = Facility A Max. Storage = 12,057 cuft Storage Indication method used. Hydrograph Volume=21,479 cuft Facility A Q (cfs) Q(cfs) Hyd. No.2— 10 Yr 18.00 — 18.00 15.00 15.00 12.00 12.00 9.00 9.00 6.00 • 6.00 3.00 3.00 0.00 0.00 0.0 0.2 0.3 0.5 0.7 0.8 1.0 1.2 1.3 1.5 1.7 Time (hrs) — Hyd No.2 — Hyd No. 1 Pond Report 'o Hydraflow Hydrographs by Intelisolve Wednesday,Aug 24 2005,12:32 PM Pond No. 1 - Facility A Pond Data Pond storage is based on known contour areas.Average end area method used. Stage/Storage Table Stage(ft) Elevation(ft) Contour area(soft) Incr.Storage(cuft) Total storage(cuft) .-i 0.00 630.00 1,100 0 0 1.00 631.00 1,535 1,318 1,318 2.00 632.00 1,970 1,753 3,070 3.00 633.00 2,760 2,365 5,435 4.00 634.00 3,550 3,155 8,590 5.00 635.00 4,750 4,150 12,740 6.00 636.00 5,950 5,350 18,090 Culvert/Orifice Structures Weir Structures [A] [B] [C] [D] [A] [B] [C] [D] Rise(in) = 24.00 12.00 0.00 0.00 Crest Len(ft) = 9.42 0.50 0.00 0.00 Span(in) = 24.00 12.00 0.00 0.00 Crest El.(ft) = 634.70 634.00 0.00 0.00 No.Barrels = 1 1 0 0 Weir Coeff. = 3.33 3.33 0.00 0.00 Invert El.(ft) = 629.80 630.00 0.00 0.00 Weir Type = Riser Rect - - Length(ft) = 41.50 0.00 0.00 0.00 Multi-Stage = Yes Yes No No Slope(%) = 0.83 0.00 0.00 0.00 N-Value = .026 .026 .013 .000 Orif.Coeff. = 0.80 0.60 0.60 0.00 Multi-Stage = n/a Yes No No Exfiltration= 0.000 in/hr(Contour) Tailwater Elev.= 0.00 ft Note:Culvert/Orifice outflows have been analyzed under Inlet and outlet control.Weir riser checked for orifice conditions. Stage(ft) Stage/Discharge Stage(ft) 6.00 6.00 • 5.00 5.00 4.00 4.00 3.00 3.00 2.00 2.00 1.00 1.00 0.00 0.00 0.00 3.00 6.00 9.00 12.00 15.00 18.00 21.00 24.00 27.00 30.00 Total Q Discharge(cfs) 11 Hydrograph Summary Report Hyd. Hydrograph Peak Time Time to Volume Inflow Maximum Maximum Hydrograph No. type flow interval peak hyd(s) elevation storage description (origin) (cfs) (min) (min) (cult) (ft) (cult) 1 Mod.Rational 21.88 1 11 28,886 — -- --- Westhall A 2 Reservoir 18.96 1 23 28,883 1 635.22 13,908 Facility A Westhall A-1YR.gpw Return Period: 100 Year Wednesday, Aug 24 2005, 12:32 PM Hvdraflow Hvdroaraohs by Intelisolve 12 Hydrograph Plot Hydraflow Hydrographs by Intelisolve Wednesday,Aug 24 2005,12:32 PM Hyd. No. 2 Facility A Hydrograph type = Reservoir Peak discharge = 18.96 cfs Storm frequency = 100 yrs Time interval = 1 min Inflow hyd. No. = 1 Max. Elevation = 635.22 ft Reservoir name = Facility A Max. Storage = 13,908 cuft Storage Indication method used. Hydrograph Volume=28,883 cuft Facility A Q(cfs) Hyd. No.2—100 Yr Q (cfs) 24.00 24.00 f 20.00 20.00 16.00 16.00 12.00 - - 12.00 8.00 - 8.00 4.00 4.00 0.00 — 0.00 0.0 0.2 0.3 0.5 0.7 0.8 1.0 1.2 1.3 1.5 Time(hrs) — Hyd No. 2 — Hyd No. 1 Pond Report 13 Hydraflow Hydrographs by Intelisolve Wednesday,Aug 24 2005,12:32 PM Pond No. 1 - Facility A Pond Data Pond storage is based on known contour areas.Average end area method used. Stage I Storage Table Stage(ft) Elevation(ft) Contour area(soft) Incr.Storage(cuft) Total storage(cuft) 0.00 630.00 1,100 0 0 1.00 631.00 1,535 1,318 1,318 2.00 632.00 1,970 1,753 3,070 3.00 633.00 2,760 2,365 5,435 4.00 634.00 3,550 3,155 8,590 5.00 635.00 4,750 4,150 12,740 6.00 636.00 5,950 5,350 18,090 Culvert/Orifice Structures Weir Structures [A] [B] [C] [D] [A] [B] [C] [D] Rise(in) = 24.00 12.00 0.00 0.00 Crest Len(ft) = 9.42 0.50 0.00 0.00 Span(in) = 24.00 12.00 0.00 0.00 Crest El.(ft) = 634.70 634.00 0.00 0.00 No.Barrels = 1 1 0 0 Weir Coeff. = 3.33 3.33 0.00 0.00 Invert El.(ft) = 629.80 630.00 0.00 0.00 Weir Type = Riser Rect - - Length(ft) = 41.50 0.00 0.00 0.00 Multi-Stage = Yes Yes No No Slope(%) = 0.83 0.00 0.00 0.00 N-Value = .026 .026 .013 .000 Orif.Coeff. = 0.80 0.60 0.60 0.00 Multi-Stage = n/a Yes No No Exfiltration= 0.000 in/hr(Contour) Tailwater Elev.= 0.00 ft Note:Culvert/Orifice outflows have been analyzed under Inlet and outlet control. Weir riser checked for orifice conditions. Stage(ft) Stage/Discharge Stage(ft) 6.00 6.00 5.00 5.00 4.00 4.00 3.00 3.00 2.00 2.00 1.00 - - 1.00 0.00 0.00 0.00 3.00 6.00 9.00 12.00 15.00 18.00 21.00 24.00 27.00 30.00 - Total Q Discharge(cfs) Table of Contents WesthallA-1YR_Tc=20 gpw Hydraflow Hydrographs by Intelisolve Wednesday,Aug 24 2005,12:41 PM Hydrograph Return Period Recap 1 1 - Year Summary Report 2 Hydrograph Reports 3 Hydrograph No. 2, Reservoir, Facility A 3 Pond Report 4 2 - Year Summary Report 5 Hydrograph Reports 6 Hydrograph No. 2, Reservoir, Facility A 6 Pond Report 7 10 - Year Summary Report 8 Hydrograph Reports 9 Hydrograph No. 2, Reservoir, Facility A 9 Pond Report 10 100 - Year Summary Report 11 Hydrograph Reports 12 Hydrograph No. 2, Reservoir, Facility A 12 Pond Report 13 • II 1 Hydrograph Return Period Recap Hyd. Hydrograph Inflow Peak Outflow(cfs) Hydrograph No. type Hyd(s) description (origin) 1-Yr 2-Yr 3-Yr 5-Yr 10-Yr 25-Yr 50-Yr 100-Yr 1 Mod.Rational — 11.91 13.05 --- — 17.08 --- — 22.85 Westhall A 2 Reservoir 1 5.91 6.21 — -- 7.71 -- -- 17.48 FacilityA Proj. file: Westhall A-1YR_Tc=20.gpw Wednesday, Aug 24 2005, 12:41 PM Hydraflow Hydrographs by Intelisolve 2 Hydrograph Summary Report Hyd. Hydrograph Peak Time Time to Volume Inflow Maximum Maximum Hydrograph No. type flow Interval peak hyd(s) elevation storage description (origin) (cfs) (min) (min) (cult) (ft) (cuff) 1 Mod.Rational 11.91 1 11 14,297 — Westhall A 2 Reservoir 5.91 1 25 13,579 1 633.58 7,262 FacilityA • Westhall A-1YR_Tc=20.gpw Return Period: 1 Year Wednesday, Aug 24 2005, 12:41 PM Hydraflow Hydrographs by Intelisolve 3 Hydrograph Plot Hydraflow Hydrographs by Intelisolve Wednesday,Aug 24 2005, 12:41 PM Hyd. No. 2 Facility A Hydrograph type = Reservoir Peak discharge = 5.91 cfs Storm frequency = 1 yrs Time interval = 1 min Inflow hyd. No. = 1 Max. Elevation = 633.58 ft Reservoir name = Facility A Max. Storage = 7,262 cuft Storage Indication method used. Hydrograph Volume=13,579 cuft Facility A Q (cfs) Hyd. No. 2— 1 Yr Q (cfs) 12.00 12.00 10.00 10.00 8.00 8.00 6.00 6.00 4.00 - - - - 4.00 2.00 2.00 0.00 — 0.00 0.0 0.2 0.3 0.5 0.7 0.8 1.0 1.2 1.3 1.5 1.7 Time (hrs) — Hyd No. 2 — Hyd No. 1 Pond Report 4 Hydraflow Hydrographs by Intelisolve Wednesday,Aug 24 2005,12:41 PM Pond No. 1 - Facility A Pond Data Pond storage is based on known contour areas.Average end area method used. Stage/Storage Table Stage(ft) Elevation(ft) Contour area(soft) Incr.Storage(cult) Total storage(cult) _ 0.00 630.00 1,100 0 0 1.00 631.00 1,535 1,318 1,318 2.00 632.00 1,970 1,753 3,070 3.00 633.00 2,760 2,365 5,435 4.00 634.00 3,550 3,155 8,590 5.00 635.00 4,750 4,150 12,740 6.00 636.00 5,950 5,350 18,090 Culvert/Orifice Structures Weir Structures [A] [B] [C] [D] [A] [B] [C] [D] Rise(in) = 24.00 12.00 0.00 0.00 Crest Len(ft) = 9.42 0.50 0.00 0.00 Span(in) = 24.00 12.00 0.00 0.00 Crest El.(ft) = 634.70 634.00 0.00 0.00 No.Barrels = 1 1 0 0 Weir Coeff. = 3.33 3.33 0.00 0.00 Invert El.(ft) = 629.80 630.00 0.00 0.00 Weir Type = Riser Rect - - Length(ft) = 41.50 0.00 0.00 0.00 Multistage = Yes Yes No No Slope(°/o) = 0.83 0.00 0.00 0.00 N-Value = .026 .026 .013 .000 Orif.Coeff. = 0.80 0.60 0.60 0.00 Multi-Stage = n/a Yes No No Exfiltration= 0.000 in/hr(Contour) Tailwater Elev.= 0.00 ft -- Note:CulvervOdiice outflows have been analyzed under Inlet and outlet control. Welr riser checked for orifice conditions. Stage(ft) Stage/Discharge Stage(ft) 6.00 6.00 -- - 5.00 _ 5.00 4.00 - - 4.00 3.00 3.00 2.00 2.00 1.00 1.00 0.00 3.00 6.00 9.00 12.00 15.00 18.00 21.00 24.00 27.00 30.00 - Total Q Discharge(cfs) 5 Hydrograph Summary Report Hyd. Hydrograph Peak Time Time to Volume Inflow Maximum Maximum Hydrograph No. type flow interval peak hyd(s) elevation storage description (origin) (cfs) (min) (min) (cuft) (ft) (cuft) 1 Mod.Rational 13.05 1 11 15,660 -- — -- Westhall A 2 Reservoir 6.21 1 25 14,874 1 633.88 8,197 FacilityA Westhall A-1YR_Tc=20.gpw Return Period: 2 Year Wednesday, Aug 24 2005, 12:41 PM Hvdraflow Hvdrocraohs by Intelisolve Hydrograph Plot 6 Hydraflow Hydrographs by Intelisolve Wednesday,Aug 24 2005,12:41 PM Hyd. No. 2 Facility A Hydrograph type = Reservoir Peak discharge = 6.21 cfs Storm frequency = 2 yrs Time interval = 1 min Inflow hyd. No. = 1 Max. Elevation = 633.88 ft Reservoir name = Facility A Max. Storage = 8,197 cuft Storage Indication method used. Hydrograph Volume=14,874 cuft Facility A Q(cfs) Hyd. No.2--2 Yr Q(cfs) 14.00 14.00 12.00 12.00 ' 10.00 10.00 8.00 8.00 6.00 6.00 4.00 4.00 2.00 2.00 0.00 --- 0.00 0.0 0.2 0.3 0.5 0.7 0.8 1.0 1.2 1.3 1.5 1.7 Time (hrs) — Hyd No. 2 — Hyd No. 1 Pond Report 7 Hydraflow Hydrographs by Intelisolve Wednesday,Aug 24 2005,12:41 PM Pond No. 1 - Facility A Pond Data Pond storage is based on known contour areas.Average end area method used. Stage/Storage Table Stage(ft) Elevation(ft) Contour area(sqft) Incr.Storage(cuft) Total storage(cuft) __ 0.00 630.00 1,100 0 0 1.00 631.00 1,535 1,318 1,318 2.00 632.00 1,970 1,753 3,070 3.00 633.00 2,760 2,365 5,435 4.00 634.00 3,550 3,155 8,590 5.00 635.00 4,750 4,150 12,740 6.00 636.00 5,950 5,350 18,090 Culvert/Orifice Structures Weir Structures [A] [B] [C] [D] [A] [B] [C] [D] Rise(in) = 24.00 12.00 0.00 0.00 Crest Len(ft) = 9.42 0.50 0.00 0.00 Span(in) = 24.00 12.00 0.00 0.00 Crest El.(ft) = 634.70 634.00 0.00 0.00 No.Barrels = 1 1 0 0 Weir Coeff. = 3.33 3.33 0.00 0.00 Invert El.(ft) = 629.80 630.00 0.00 0.00 Weir Type = Riser Rect - - Length(ft) = 41.50 0.00 0.00 0.00 Multi-Stage = Yes Yes No No Slope(%) = 0.83 0.00 0.00 0.00 _ N-Value = .026 .026 .013 .000 Orif.Coeff. = 0.80 0.60 0.60 0.00 Multi-Stage = n/a Yes No No Exfiltration= 0.000 in/hr(Contour) Tailwater Elev.= 0.00 ft - Note:CulvertrOdfice outflows have been analyzed under inlet and outlet control. Weir riser checked for orifice conditions. I Stage(ft) Stage/Discharge Stage(ft) 6.00 6.00 la5.00 - 5.00 4.00 4.00 3.00 3.00 I WM 2.00 - ---- - 2.00 1.00 1.00 0.00 0.00 0.00 3.00 6.00 9.00 12.00 15.00 18.00 21.00 24.00 27.00 30.00 - Total Q Discharge(cfs) 8 Hydrograph Summary Report Hyd. Hydrograph Peak Time Time to Volume Inflow Maximum Maximum Hydrograph No. type flow interval peak hyd(s) elevation storage description (origin) (cfs) (min) (min) (cult) (ft) (cult) 1 Mod.Rational 17.08 1 11 20,501 — Westhall A 2 Reservoir 7.71 1 25 .19,473 1 634.69 11,474 FacilityA • Westhall A-1YR_Tc=20.gpw Return Period: 10 Year Wednesday, Aug 24 2005, 12:41 PM Hydraflow Hydrographs by Intelisolve 9 Hydrograph Plot Hydraflow Hydrographs by Intelisolve Wednesday,Aug 24 2005,12:41 PM Hyd. No. 2 Facility A Hydrograph type = Reservoir Peak discharge = 7.71 cfs Storm frequency = 10 yrs Time interval = 1 min Inflow hyd. No. = 1 Max. Elevation = 634.69 ft Reservoir name = Facility A Max. Storage = 11,474 cult Storage Indication method used. Hydrograph Volume=19,473 cuft Facility A Q (cfs) Hyd. No.2— 10 Yr Q (cfs) 18.00 18.00 15.00 15.00 12.00 12.00 9.00 9.00 6.00 6.00 3.00 3.00 0.00 0.00 0.0 0.2 0.3 0.5 0.7 0.8 1.0 1.2 1.3 1.5 1.7 Time(hrs) — Hyd No. 2 — Hyd No. 1 Pond Report 10 Hydraflow Hydrographs by Intelisolve Wednesday,Aug 24 2005, 12:41 PM Pond No. 1 - Facility A Pond Data Pond storage is based on known contour areas.Average end area method used. Stage/Storage Table Stage(ft) Elevation(ft) Contour area(sgft) Incr.Storage(cult) Total storage(cult) 0.00 630.00 1,100 0 0 1.00 631.00 1,535 1,318 1,318 2.00 632.00 1,970 1,753 3,070 1 3.00 633.00 2,760 2,365 5,435 4.00 634.00 3,550 3,155 8,590 5.00 635.00 4,750 4,150 12,740 6.00 636.00 5,950 5,350 18,090 Culvert/Orifice Structures Weir Structures [A] [B] [C] [D] [A] [B] [C] [D] ' Rise(in) = 24.00 12.00 0.00 0.00 Crest Len(ft) = 9.42 0.50 0.00 0.00 Span(In) = 24.00 12.00 0.00 0.00 Crest El.(ft) = 634.70 634.00 0.00 0.00 No.Barrels = 1 1 0 0 Weir Coeff. = 3.33 3.33 0.00 0.00 Invert El.(ft) = 629.80 630.00 0.00 0.00 Weir Type = Riser Rect - - Length(ft) = 41.50 0.00 0.00 0.00 Multistage = Yes Yes No No Slope(%) = 0.83 0.00 0.00 0.00 ' N-Value = .026 .026 .013 .000 Orif.Coeff. = 0.80 0.60 0.60 0.00 Multi-Stage = n/a Yes No No Exflltration= 0.000 in/hr(Contour) Tailwater Elev.= 0.00 ft Note:Culvert/Orifice outflows have been analyzed under Inlet and outlet control. Weir riser checked for orifice conditions. Stage(ft) Stage/Discharge Stage(ft) 6.00 / 6.00 . 5.00 5.00 4.00 4.00 3.00 3.00 • 2.00 .. _ 2.00 1.00 1.00 0.00 0.00 0.00 3.00 6.00 9.00 12.00 15.00 18.00 21.00 24.00 27.00 30.00 Total Q Discharge(cfs) 11 Hydrograph Summary Report Hyd. Hydrograph Peak lime Time to Volume Inflow Maximum Maximum Hydrograph No. type flow interval peak hyd(s) elevation storage description (origin) (cfs) (min) (min) (cuft) (ft) (cuft) 1 Mod.Rational 22.85 1 11 27,415 — — Westhall A 2 Reservoir 17.48 1 22 26,041 1 635.17 13,632 Facility A • • Westhall A-1YR_Tc=20.gpw Return Period: 100 Year Wednesday, Aug 24 2005, 12:41 PM Hydratow Hydrographs by Intelisolve 12 Hydrograph Plot Hydraflow Hydrographs by Intelisolve Wednesday,Aug 24 2005,12:41 PM Hyd. No. 2 Facility A Hydrograph type = Reservoir Peak discharge = 17.48 cfs Storm frequency = 100 yrs Time interval = 1 min Inflow hyd. No. = 1 Max. Elevation = 635.17 ft Reservoir name = Facility A Max. Storage = 13,632 cuft Storage Indication method used. Hydrograph Volume=26,041 cuft Facility A Q(cfs) Hyd. No. 2 — 100 Yr Q(cfs) — 24.00 24.00 20.00 20.00 16.00 16.00 12.00 12.00 8.00 8.00 Pr 4.00 4.00 0.00 0.00 0.0 0.2 0.3 0.5 0.7 0.8 1.0 1.2 1.3 1.5 Time (hrs) — Hyd No.2 — Hyd No. 1 Pond Report 13 Hydraflow Hydrographs by Intelisolve Wednesday,Aug 24 2005, 12:41 PM Pond No. 1 - FacilityA Pond Data Pond storage is based on known contour areas.Average end area method used. Stage/Storage Table 1 Stage(ft) Elevation(ft) Contour area(soft) Incr.Storage(cuft) Total storage(cuft) _ 0.00 630.00 1,100 0 0 1.00 631.00 1,535 1,318 1,318 2.00 632.00 1,970 1,753 3,070 3.00 633.00 2,760 2,365 5,435 4.00 634.00 3,550 3,155 8,590 5.00 635.00 4,750 4,150 12,740 6.00 636.00 5,950 5,350 18,090 Culvert/Orifice Structures Weir Structures [A] [B] [C] [D] [A] [B] [C] [D] Rise(in) = 24.00 12.00 0.00 0.00 Crest Len(ft) = 9.42 0.50 0.00 0.00 - Span(In) = 24.00 12.00 0.00 0.00 Crest El.(ft) = 634.70 634.00 0.00 0.00 No.Barrels = 1 1 0 0 Weir Coeff. = 3.33 3.33 0.00 0.00 Invert El.(ft) = 629.80 630.00 0.00 0.00 Weir Type = Riser Rect - - Length(ft) = 41.50 0.00 0.00 0.00 Multi-Stage = Yes Yes No No Slope(%) = 0.83 0.00 0.00 0.00 N-Value = .026 .026 .013 .000 Orif.Coeff. = 0.80 0.60 0.60 0.00 Multi-Stage = n/a Yes No No Exfiltration= 0.000 in/hr(Contour) Tailwater Elev.= 0.00 ft Note:Culvert/Odfice outflows have been analyzed under Inlet and outlet control. Welr riser checked for orifice conditions. Stage(ft) Stage/Discharge Stage(ft) 6.00 6.00 5.00 / 5.00 4.00 4.00 3.00 3.00 2.00 2.00 1.00 1.00 0.00 0.00 0.00 3.00 6.00 9.00 12.00 15.00 18.00 21.00 24.00 27.00 30.00 Discharge(cfs) - Total Q Table of Contents Westhall A-1YR_Tc=24 gpw Hydraflow Hydrographs by Intelisolve Wednesday,Aug 24 2005,10:33 AM Hydrograph Return Period Recap 1 1 - Year Summary Report 2 Hydrograph Reports 3 Hydrograph No. 2, Reservoir, Facility A 3 Pond Report 4 2 - Year Summary Report 5 Hydrograph Reports 6 Hydrograph No. 2, Reservoir, Facility A 6 Pond Report 7 10 - Year Summary Report 8 Hydrograph Reports 9 Hydrograph No. 2, Reservoir, Facility A 9 Pond Report 10 100 - Year Summary Report 11 Hydrograph Reports 12 Hydrograph No. 2, Reservoir, Facility A 12 Pond Report 13 1 Hydrograph Return Period Recap Hyd. Hydrograph Inflow Peak Outflow(cfs) Hydrograph No. type Hyd(s) description (origin) 1-Yr 2-Yr 3-Yr 5-Yr 10-Yr 25-Yr 50-Yr 100-Yr 1 Mod.Rational — 10.78 11.79 — — 15.55 — — 21.02 Westhall A 2 Reservoir 1 5.99 6.28 — — 8.69 — — 18.52 FacilityA Proj. file: Westhall A-1YR_Tc=24.gpw Wednesday, Aug 24 2005, 10:33 AM Hydraflow Hydrographs by Intelisolve 2 Hydrograph Summary Report Hyd. Hydrograph Peak Time Time to Volume Inflow Maximum Maximum Hydrograph No. type flow interval peak hyd(s) elevation storage description (origin) (cfs) (min) (min) (cult) (ft) (tuft) 1 Mod.Rational 10.78 1 11 15,519 — — — Westhall A 2 Reservoir 5.99 1 28 14,870 1 633.65 7,497 FacilityA Westhall A-1YR_Tc=24.gpw Return Period: 1 Year Wednesday, Aug 24 2005, 10:33 AM Hydraflow Hydrographs by Intelisolve 3 Hydrograph Plot Hydraflow Hydrographs by Intelisolve Wednesday,Aug 24 2005, 10:33 AM Hyd. No. 2 Facility A Hydrograph type = Reservoir Peak discharge = 5.99 cfs Storm frequency = 1 yrs Time interval = 1 min Inflow hyd. No. = 1 Max. Elevation = 633.65 ft Reservoir name = Facility A Max. Storage = 7,497 cult Storage Indication method used. Hydrograph Volume=14,870 cult Facility A Q (cfs) Hyd. No. 2 — 1 Yr Q(cfs) 12.00 12.00 10.00 10.00 8.00 8.00 6.00 6.00 4.00 4.00 2.00 2.00 0.00 — 0.00 0.0 0.2 0.3 0.5 0.7 0.8 1.0 1.2 1.3 1.5 1.7 Time (hrs) — Hyd No.2 — Hyd No. 1 Pond Report 4 Hydraflow Hydrographs by Intelisolve Wednesday,Aug 24 2005, 10:33 AM Pond No. 1 - Facility A Pond Data Pond storage is based on known contour areas.Average end area method used. I Stage/Storage Table Stage(ft) Elevation(ft) Contour area(sqft) Incr.Storage(cuft) Total storage(cuft) 0.00 630.00 1,100 - 0 0 1.00 631.00 1,535 1,318 1,318 2.00 632.00 1,970 1,753 3,070 3.00 633.00 2,760 2,365 5,435 4.00 634.00 3,550 3,155 8,590 5.00 635.00 4,750 4,150 12,740 6.00 636.00 5,950 5,350 18,090 Culvert/Orifice Structures Weir Structures [A] [B] [C] [D] [A] [B] [C] [D] Rise(in) = 24.00 12.00 0.00 0.00 Crest Len(ft) = 9.42 0.50 0.00 0.00 Span(in) = 24.00 12.00 0.00 0.00 Crest El.(ft) = 634.70 634.00 0.00 0.00 No.Barrels = 1 1 0 0 Weir Coeff. = 3.33 3.33 0.00 0.00 Invert El.(ft) = 629.80 630.00 0.00 0.00 Weir Type = Riser Rect - - Length(ft) = 41.50 0.00 0.00 0.00 Multi-Stage = Yes Yes No No Slope(%) = 0.83 0.00 0.00 0.00 N-Value = .026 .026 .013 .000 Orif.Coeff. = 0.80 0.60 0.60 0.00 Multi-Stage = n/a Yes No No Exfiltration= 0.000 in/hr(Contour) Tailwater Elev.= 0.00 ft Note:Culvert/Orifice outflows have been analyzed under Inlet and outlet control. Weir riser checked for orifice conditions. Stage(ft) Stage/Discharge Stage(ft) 6.00 6.00 5.00 5.00 4.00 4.00 3.00 3.00 2.00 -- - --_.- 2.00 1.00 1.00 -- 0.00 0.00 0.00 3.00 6.00 9.00 12.00 15.00 18.00 21.00 24.00 27.00 30.00 - Total Q Discharge(cfs) 5 Hydrograph Summary Report Hyd. Hydrograph Peak Time Time to Volume Inflow Maximum Maximum Hydrograph No. type flow interval peak hyd(s) elevation storage description (origin) (cfs) (min) (min) (cult) (ft) (cuft) 1 Mod.Rational 11.79 1 11 16,978 — Westhall A 2 Reservoir 6.28 1 28 16,268 1 633.96 8,471 FacilityA Westhall A-1YR_Tc=24.gpw Return Period: 2 Year Wednesday, Aug 24 2005, 10:33 AM Hydraflow Hydrographs by Intelisolve 6 Hydrograph Plot Hydraflow Hydrographs by Intelisolve Wednesday,Aug 24 2005, 10:33 AM Hyd. No. 2 Facility A Hydrograph type = Reservoir Peak discharge = 6.28 cfs Storm frequency = 2 yrs Time interval = 1 min Inflow hyd. No. = 1 Max. Elevation = 633.96 ft Reservoir name = Facility A Max. Storage = 8,471 cuft Storage Indication method used. Hydrograph Volume=16,268 cuft Facility A Q (cfs) Hyd. No. 2—2 Yr Q(cfs) 12.00 12.00 10.00 - — - -- 10.00 8.00 8.00 6.00 6.00 4.00 4.00 2.00 2.00 0.00 — 0.00 0.0 0.2 0.3 0.5 0.7 0.8 1.0 1.2 1.3 1.5 1.7 Time (hrs) — Hyd No. 2 — Hyd No. 1 Pond Report 7 Hydraflow Hydrographs by Intelisolve Wednesday,Aug 24 2005, 10:33 AM Pond No. t - Facility A Pond Data Pond storage is based on known contour areas.Average end area method used. Stage/Storage Table Stage(ft) Elevation(ft) Contour area(soft) Incr.Storage(cuff) Total storage(cult) 0.00 630.00 1,100 0 0 1.00 631.00 1,535 1,318 1,318 2.00 632.00 1,970 1,753 3,070 3.00 633.00 2,760 2,365 5,435 4.00 634.00 3,550 3,155 8,590 5.00 635.00 4,750 4,150 12,740 6.00 636.00 5,950 5,350 18,090 Culvert/Orifice Structures Weir Structures [A] [B] [C] [D] [A] [B] [C] [D] Rise(in) = 24.00 12.00 0.00 0.00 Crest Len(ft) = 9.42 0.50 0.00 0.00 Span(in) = 24.00 12.00 0.00 0.00 Crest El.(ft) = 634.70 634.00 0.00 0.00 No.Barrels = 1 1 0 0 Weir Coeff. = 3.33 3.33 0.00 0.00 Invert El.(ft) = 629.80 630.00 0.00 0.00 Weir Type = Riser Rect - - Length(ft) = 41.50 0.00 0.00 0.00 Multistage = Yes Yes No No Slope(%) = 0.83 0.00 0.00 0.00 N-Value = .026 .026 .013 .000 Orif.Coeff. = 0.80 0.60 0.60 0.00 Multi-Stage = n/a Yes No No Exfiltration= 0.000 in/hr(Contour) Tailwater Elev.= 0.00 ft Note:CulveruOdfce outflows have been analyzed under inlet and outlet control.Weir riser checked for orifice conditions. Stage(ft) Stage/Discharge Stage(ft) 6.00 _ 6.00 - --1 5.00 - 5.00 4.00 4.00 3.00 3.00 2.00 2.00 1.00 1.00 1 7- 0.00 0.00 0.00 3.00 6.00 9.00 12.00 15.00 18.00 21.00 24.00 27.00 30.00 -[ Discharge(cfs) 1 1 - Total O 8 Hydrograph Summary Report _ Hyd. Hydrograph Peak Time Time to Volume Inflow Maximum Maximum Hydrograph No. type flow interval peak hyd(s) elevation storage description (origin) (cfs) (min) (min) (cuft) (ft) (cuff) 1 Mod.Rational 15.55 1 11 22,389 -- --- -- Westhall A 2 Reservoir 8.69 1 28 21,453 1 634.80 11,920 FacilityA r Westhall A-1YR_Tc=24.gpw Return Period: 10 Year Wednesday, Aug 24 2005, 10:33 AM Hydraflow Hydrographs by Intelisolve Hydrograph Plot 9 Hydraflow Hydrographs by Intelisolve Wednesday,Aug 24 2005, 10:33 AM Hyd. No. 2 Facility A Hydrograph type = Reservoir Peak discharge = 8.69 cfs Storm frequency = 10 yrs Time interval = 1 min Inflow hyd. No. = 1 Max. Elevation = 634.80 ft Reservoir name = Facility A Max. Storage = 11,920 cult Storage Indication method used. Hydrograph Volume=21,453 cuft Facility A Q (cfs) Hyd. No. 2 -- 10 Yr Q(cfs) 18.00 18.00 15.00 f 15.00 12.00 12.00 9.00 9.00 6.00 6.00 • 3.00 3.00 0.00 0.00 0.0 0.2 0.3 0.5 0.7 0.8 1.0 1.2 1.3 1.5 1.7 Time (hrs) — Hyd No. 2 — Hyd No. 1 Pond Report 'o Hydraflow Hydrographs by Intelisolve Wednesday,Aug 24 2005,10:33 AM Pond No. 1 - Facility A Pond Data Pond storage is based on known contour areas.Average end area method used. Stage/Storage Table Stage(ft) Elevation(ft) Contour area(sqft) Incr.Storage(cuft) Total storage(cult) 0.00 630.00 1,100 0 0 1.00 631.00 1,535 1,318 1,318 2.00 632.00 1,970 1,753 3,070 3.00 633.00 2,760 2,365 5,435 4.00 634.00 3,550 3,155 8,590 5.00 635.00 4,750 4,150 12,740 6.00 636.00 5,950 5,350 18,090 Culvert/Orifice Structures Weir Structures [A] [B] [C] [D] [A] [B] [C] [D] Rise(in) = 24.00 12.00 0.00 0.00 Crest Len(ft) = 9.42 0.50 0.00 0.00 Span(in) = 24.00 12.00 0.00 0.00 Crest El.(ft) = 634.70 634.00 0.00 0.00 No.Barrels = 1 1 0 0 Weir Coeff. = 3.33 3.33 0.00 0.00 Invert El.(ft) = 629.80 630.00 0.00 0.00 Weir Type = Riser Rect - - Length(ft) = 41.50 0.00 0.00 . 0.00 Multi-Stage = Yes Yes No No Slope(%) = 0.83 0.00 0.00 0.00 N-Value = .026 .026 .013 .000 Orif.Coeff. = 0.80 0.60 0.60 0.00 Multi-Stage = n/a Yes No No Exfiltration= 0.000 in/hr(Contour) Tailwater Elev.= 0.00 ft Note:Culveruorfice outflows have been analyzed under inlet and outlet control. Weir dser checked for orifice conditions. Stage(ft) Stage/Discharge Stage(ft) 6.00 I 6.00 5.00 5.00 - 4.00 4.00 3.00 3.00 2.00 2.00 1.00 1.00 0.00 - - 0.00 0.00 3.00 6.00 9.00 12.00 15.00 18.00 21.00 24.00 27.00 30.00 Discharge(cfs) - Total O 11 Hydrograph Summary Report Hyd. Hydrograph Peak Time Time to Volume Inflow Maximum Maximum Hydrograph No. type flow interval peak hyd(s) elevation storage description (origin) (cfs) (min) (min) (cuft) (ft) (cuft) 1 Mod.Rational 21.02 1 11 30,276 --- Westhall A 2 Reservoir 18.52 1 24 29,011 1 635.20 13,828 FacilityA Westhall A-1YR_Tc=24.gpw Return Period: 100 Year Wednesday, Aug 24 2005, 10:33 AM Hydraflow Hydrographs by Intelisolve 12 Hydrograph Plot Hydraflow Hydrographs by Intelisolve Wednesday,Aug 24 2005, 10:33 AM Hyd. No. 2 Facility A Hydrograph type = Reservoir Peak discharge = 18.52 cfs Storm frequency = 100 yrs Time interval = 1 min Inflow hyd. No. = 1 Max. Elevation = 635.20 ft Reservoir name = Facility A Max. Storage = 13,828 cuff Storage Indication method used. Hydrograph Volume=29,011 cuft Facility A Q(cfs) Q(cfs) Hyd. No.2-- 100 Yr 24.00 24.00 20.00 20.00 16.00 16.00 12.00 12.00 8.00 8.00 4.00 4.00 \.\ - , 0.00 0.00 0.0 0.2 0.3 0.5 0.7 0.8 1.0 1.2 1.3 1.5 Time (his) Hyd No. 2 — Hyd No. 1 Pond Report 13 Hydraflow Hydrographs by Intelisolve Wednesday,Aug 24 2005, 10:33 AM Pond No. 1 - Facility A Pond Data Pond storage is based on known contour areas.Average end area method used. Stage/Storage Table Stage(ft) Elevation(ft) Contour area(soft) Incr.Storage(cult) Total storage(cult) 0.00 630.00 1,100 0 0 1.00 631.00 1,535 1,318 1,318 2.00 632.00 1,970 1,753 3,070 3.00 633.00 2,760 2,365 5,435 4.00 634.00 3,550 3,155 8,590 5.00 635.00 4,750 4,150 12,740 6.00 636.00 5,950 5,350 18,090 Culvert/Orifice Structures Weir Structures L [A] [B] [C] [D] [A] [B] [C] [D] Rise(In) = 24.00 12.00 0.00 0.00 Crest Len(ft) = 9.42 0.50 0.00 0.00 Span(in) = 24.00 12.00 0.00 0.00 Crest El.(ft) = 634.70 634.00 0.00 0.00 No.Barrels = 1 1 0 0 Weir Coeff. = 3.33 3.33 0.00 0.00 Invert El.(ft) = 629.80 630.00 0.00 0.00 Weir Type = Riser Rect - - Length(ft) = 41.50 0.00 0.00 0.00 Multi-Stage = Yes Yes No No Slope(%) = 0.83 0.00 0.00 0.00 N-Value = .026 .026 .013 .000 Orif.Coeff. = 0.80 0.60 0.60 0.00 Multi-Stage = n/a Yes No No Exfiltration= 0.000 in/hr(Contour) Tailwater Elev.= 0.00 ft Note:Culvert/Oriilce outflows have been analyzed under inlet and outlet control. Weir riser checked for orifice conditions. Stage(ft) Stage/Discharge Stage(ft) 6.00 J 6.00 5.00 5.00 4.00 4.00 3.00 3.00 2.00 2.00 • 1.00 1.00 0.00 0.00 0.00 3.00 6.00 9.00 12.00 15.00 18.00 21.00 24.00 27.00 30.00 Discharge(cfs) Total Q Table of Contents Westhall A-1YR_Rational.gpw -- Hydraflow Hydrographs by Intelisolve Wednesday,Aug 24 2005,10:56 AM Hydrograph Return Period Recap 1 1 - Year Summary Report 2 Hydrograph Reports 3 Hydrograph No. 2, Reservoir, Facility A 3 Pond Report 4 • 2 - Year Summary Report 5 Hydrograph Reports 6 Hydrograph No. 2, Reservoir, Facility A 6 Pond Report 7 10 - Year Summary Report 8 Hydrograph Reports 9 Hydrograph No. 2, Reservoir, Facility A 9 Pond Report 10 100 - Year Summary Report 11 Hydrograph Reports 12 Hydrograph No. 2, Reservoir, Facility A 12 Pond Report 13 1 Hydrograph Return Period Recap Hyd. Hydrograph Inflow Peak Outflow(cfs) Hydrograph No. type Hyd(s) description (origin) 1-Yr 2-Yr 3-Yr 5-Yr 10-Yr 25-Yr 50-Yr 100-Yr 1 Rational — 15.83 17.31 --- -- 22.34 — — 29.26 Westhall A 2 Reservoir 1 5.58 5.81 — — 6.67 — — 11.58 Facility A Proj. file: Westhall A-1YR_Rational.gpw Wednesday, Aug 24 2005, 10:56 AM Hydraflow Hydrographs by Intelisolve 2 Hydrograph Summary Report Hyd. Hydrograph Peak Time Time to Volume Inflow Maximum Maximum Hydrograph No. type flow interval peak hyd(s) elevation storage description (origin) (cfs) (min) (min) (cuft) (ft) (cuft) 1 Rational 15.83 1 11 10,445 — --- — Westhall A 2 Reservoir 5.58 1 18 10,442 1 633.25 6,218 Facility A • Westhall A-1YR_Rational.gpw Return Period: 1 Year Wednesday, Aug 24 2005, 10:56 AM Hydraflow Hydrographs by Intelisolve 3 Hydrograph Plot Hydraflow Hydrographs by Intelisolve Wednesday,Aug 24 2005, 10:56 AM Hyd. No. 2 Facility A Hydrograph type = Reservoir Peak discharge = 5.58 cfs Storm frequency = 1 yrs Time interval = 1 min Inflow hyd. No. = 1 Max. Elevation = 633.25 ft Reservoir name = Facility A Max. Storage = 6,218 cuft Storage Indication method used. Hydrograph Volume r.10,442 cuft Facility A Q(cfs) Q(cis) Hyd. No. 2-- 1 Yr ' 18.00 18.00 i 15.00 15.00 12.00 , 12.00 9.00 /7 I 9.00 , 6.00 6.00 3.00 3.00 0.00 0.00 0.0 0.2 0.3 0.5 0.7 0.8 1.0 1.2 1.3 1.5 Time (his) - 1 — Hyd No.2 — Hyd No. 1 I Pond Report 4 Hydrafiow Hydrographs by Intelisolve Wednesday,Aug 24 2005, 10:56 AM Pond No. 1 - Facility A Pond Data Pond storage is based on known contour areas.Average end area method used. Stage/Storage Table Stage(ft) Elevation(ft) Contour area(sgft) Incr.Storage(cuft) Total storage(cuft) 0.00 630.00 1,100 0 0 1.00 631.00 1,535 1,318 1,318 2.00 632.00 1,970 1,753 3,070 3.00 633.00 2,760 2,365 5,435 4.00 634.00 3,550 3,155 8,590 5.00 635.00 • 4,750 4,150 12,740 6.00 636.00 5,950 5,350 18,090 Culvert/Orifice Structures Weir Structures [A] [B] [C] [D] [A] [B] [C] [D] Rise(in) = 24.00 12.00 0.00 0.00 Crest Len(ft) = 9.42 0.50 0.00 0.00 Span(in) = 24.00 12.00 0.00 0.00 Crest El.(ft) = 634.70 634.00 0.00 0.00 No.Barrels = 1 1 0 0 Weir Coeff. = 3.33 3.33 0.00 0.00 Invert El.(ft) = 629.80 630.00 0.00 0.00 Welr Type = Riser Rect - - Length(ft) = 41.50 0.00 0.00 0.00 Multistage = Yes Yes No No Slope(%) = 0.83 0.00 0.00 0.00 N-Value = .026 .026 .013 .000 Orif.Coeff. = 0.80 0.60 0.60 0.00 Multi-Stage = n/a Yes No No Exfiltration= 0.000 in/hr(Contour) Tailwater Elev.= 0.00 ft Note:Culvert/Orifice outflows have been analyzed under inlet and outlet control.Weir riser checked for onfce conditions. Stage(ft) Stage/Discharge Stage(ft) 6.00 6.00 5.00 5.00 4.00 4.00 3.00 3.00 2.00 2.00 1.00 1.00 0.00 0.00 0.00 3.00 6.00 9.00 12.00 15.00 18.00 21.00 24.00 27.00 30.00 Discharge(cfs) - Total Q 5 Hydrograph Summary Report Hyd. Hydrograph Peak Time Time to Volume Inflow Maximum Maximum Hydrograph No. type flow interval peak hyd(s) elevation storage description (origin) (cfs) (min) (min) (cuff) (ft) (cult) 1 Rational 17.31 1 11 11,422 — -- Westhall A 2 Reservoir 5.81 1 18 11,419 1 633.48 6,951 FacilityA Westhall A-1YR Rational.gpw Return Period: 2 Year Wednesday, Aug 24 2005, 10:56 AM Hydraflow Hydrographs by Intelisolve 6 - Hydrograph Plot Hydraflow Hydrographs by Intelisolve Wednesday,Aug 24 2005,10:56 AM Hyd. No. 2 Facility A Hydrograph type = Reservoir Peak discharge = 5.81 cfs Storm frequency = 2 yrs Time interval = 1 min Inflow hyd. No. = 1 Max. Elevation = 633.48 ft Reservoir name = Facility A Max. Storage = 6,951 cuft Storage Indication method used. Hydrograph Volume=11,419 cuft Facility A Q(cfs) Q(cfs) Hyd. No.2--2 Yr ' 18.00 18.00 15.00 15.00 12.00 12.00 9.00 9.00 6.00 6.00 3.00 3.00 0.00 0.00 0.0 0.2ji 0.3 0.5 0.7 0.8 1.0 1.2 1.3 1.5 Time (his) — Hyd No. 2 — Hyd No. 1 Pond Report Hydraflow Hydrographs by Intelisolve Wednesday,Aug 24 2005, 10:56 AM Pond No. 1 - Facility A Pond Data Pond storage is based on known contour areas.Average end area method used. Stage/Storage Table Stage(ft) Elevation(ft) Contour area(sett) Incr.Storage(cult) Total storage(cuff) 0.00 630.00 1,100 0 0 1.00 631.00 1,535 1,318 1,318 2.00 632.00 1,970 1,753 3,070 3.00 633.00 2,760 2,365 5,435 4.00 634.00 3,550 3,155 8,590 5.00 635.00 4,750 4,150 12,740 6.00 636.00 5,950 5,350 18,090 Culvert/Orifice Structures Weir Structures [A] [B] [C] [D] [A] [B] [C] [D] Rise(in) = 24.00 12.00 0.00 0.00 Crest Len(ft) = 9.42 0.50 0.00 0.00 Span(in) = 24.00 12.00 0.00 0.00 Crest El.(ft) = 634.70 634.00 0.00 0.00 No.Barrels = 1 1 0 0 Weir Coeff. = 3.33 3.33 0.00 0.00 Invert El.(ft) = 629.80 630.00 0.00 0.00 Weir Type = Riser Rect - - Length(ft) = 41.50 0.00 0.00 0.00 Multi-Stage = Yes Yes No No Slope(%) = 0.83 0.00 0.00 0.00 N-Value = .026 .026 .013 .000 Orif.Coeff. = 0.80 0.60 0.60 0.00 Multistage = n/a Yes No No Exfiltration= 0.000 in/hr(Contour) Tailwater Elev.= 0.00 ft Note:Culvert/Orifice outflows have been analyzed under inlet and outlet control. Weir riser checked for orifice conditions. Stage(ft) Stage/Discharge Stage(ft) 6.00 6.00 5.00 ® 5.00 4.00 4.00 3.00 3.00 2.00 2.00 1.00 1.00 0.00 0.00 0.00 3.00 6.00 9.00 12.00 15.00 18.00 21.00 24.00 27.00 30.00 Discharge(cfs) Total Q 8 Hydrograph Summary Report Hyd. Hydrograph Peak Time Time to Volume Inflow Maximum Maximum Hydrograph No. type flow interval peak hyd(s) elevation storage description (origin) (cfs) (min) (min) (cuft) (ft) (cuft) 1 Rational 22.34 1 11 14,748 — WesthallA 2 Reservoir 6.67 1 19 14,745 1 634.23 9,531 Facility A • Westhall A-1YR_Rational.gpw Return Period: 10 Year Wednesday, Aug 24 2005, 10:56 AM Hydraflow Hydrographs by Intelisolve 9 Hydrograph Plot Hydraflow Hydrographs by Intelisolve Wednesday,Aug 24 2005,10:56 AM Hyd. No. 2 Facility A Hydrograph type = Reservoir Peak discharge = 6.67 cfs Storm frequency = 10 yrs Time interval = 1 min Inflow hyd. No. = 1 Max. Elevation = 634.23 ft Reservoir name = Facility A Max. Storage = 9,531 cuft Storage Indication method used. Hydrograph Volume=14,745 cult Facility A Q(cfs) Hyd. No.2-- 10 Yr Q(cfs) 24.00 24.00 20.00 20.00 16.00 16.00 12.00 12.00 8.00 8.00 4.00 4.00 0.00 0.00 0.0 0.2 0.3 0.5 0.7 0.8 1.0 1.2 1.3 1.5 Time (hrs) — Hyd No.2 — Hyd No. 1 Pond Report 'o Hydraflow Hydrographs by Intelisolve Wednesday,Aug 24 2005, 10:56 AM Pond No. 1 - Facility A Pond Data Pond storage is based on known contour areas.Average end area method used. Stage/Storage Table Stage(ft) Elevation(ft) Contour area(sgft) Incr.Storage(cuft) Total storage(cuft) 0.00 630.00 1,100 0 0 1.00 631.00 1,535 1,318 1,318 2.00 632.00 1,970 1,753 3,070 3.00 633.00 2,760 2,365 5,435 4.00 634.00 3,550 3,155 8,590 5.00 635.00 4,750 4,150 12,740 6.00 636.00 5,950 5,350 18,090 Culvert/Orifice Structures Weir Structures [A] [B] [C] [D] [A] [B] [C] [D] Rise(in) = 24.00 12.00 0.00 0.00 Crest Len(ft) = 9.42 0.50 0.00 0.00 Span(in) = 24.00 12.00 0.00 0.00 Crest El.(ft) = 634.70 634.00 0.00 0.00 No.Barrels = 1 1 0 0 Weir Coeff. = 3.33 3.33 0.00 0.00 Invert El.(ft) = 629.80 630.00 0.00 0.00 Weir Type = Riser Red - - Length(ft) = 41.50 0.00 0.00 0.00 Multistage = Yes Yes No No Slope(%) = 0.83 0.00 0.00 0.00 N-Value = .026 .026 .013 .000 Orif.Coeff. = 0.80 0.60 0.60 0.00 Multi-Stage = n/a Yes No No Exfiltration= 0.000 in/hr(Contour) Tailwater Elev.= 0.00 ft Note:Culvert/Orifice outflows have been analyzed under inlet and outlet control. Weir riser checked for orifice conditions. Stage(ft) Stage/Discharge Stage(ft) 6.00 6.00 5.00 MSS 5.00 4.00 4.00 3.00 3.00 II 2.00 2.00 1.00 I 1.00 r - - 0.00 0.00 0.00 3.00 6.00 9.00 12.00 15.00 18.00 21.00 24.00 27.00 30.00 Discharge(cfs) - Total Q 11 Hydrograph Summary Report Hyd. Hydrograph Peak Time Time to Volume Inflow Maximum Maximum Hydrograph No. type flow interval peak hyd(s) elevation storage description (origin) (cfs) (min) (min) (cuft) (ft) (cuft) 1 Rational 29.26 1 11 19,312 — Westhall A 2 Reservoir 11.58 1 18 19,309 1 634.94 12,502 FacilityA Westhall A-1YR_Rational.gpw Return Period: 100 Year Wednesday, Aug 24 2005, 10:56 AM Hydraflow Hydrographs by Intelisolve 12 Hydrograph Plot Hydraflow Hydrographs by Intelisolve Wednesday,Aug 24 2005, 10:56 AM Hyd. No. 2 Facility A Hydrograph type = Reservoir Peak discharge = 11.58 cfs Storm frequency = 100 yrs Time interval = 1 min ' Inflow hyd. No. = 1 Max. Elevation = 634.94 ft Reservoir name = Facility A Max. Storage = 12,502 cuft Storage Indication method used. Hydrograph Volume=19,309 cuft Facility A Q(cfs) Q (cfs) Hyd. No. 2 — 100 Yr 30.00 30.00 25.00 25.00 20.00 20.00 ' 15.00 15.00 10.00 10.00 5.00 5.00 0.00 0.00 0.0 0.2 _0.3 0.5 0.7 0.8 1.0 1.2 1.3 1.5 Time (hrs) — Hyd No. 2 — Hyd No. 1 Pond Report 13 Hydraflow Hydrographs by Intelisolve Wednesday,Aug 24 2005, 10:56 AM Pond No. 1 - Facility A Pond Data Pond storage is based on known contour areas.Average end area method used. Stage/Storage Table Stage(ft) Elevation(ft) Contour area(sgft) Incr.Storage(cult) Total storage(cuft) 0.00 630.00 1,100 0 0 1.00 631.00 1,535 1,318 1,318 2.00 632.00 1,970 1,753 3,070 3.00 633.00 2,760 2,365 5,435 4.00 634.00 3,550 3,155 8,590 5.00 635.00 4,750 4,150 12,740 6.00 636.00 5,950 5,350 18,090 Culvert/Orifice Structures Weir Structures [A] [B] [C] [D] [A] [B] [C] [D] Rise(in) = 24.00 12.00 0.00 0.00 Crest Len(ft) = 9.42 0.50 0.00 0.00 Span(in) = 24.00 12.00 0.00 0.00 Crest El.(ft) = 634.70 634.00 0.00 0.00 No.Barrels = 1 1 0 0 Weir Coeff. = 3.33 3.33 0.00 0.00 ' Invert El.(ft) = 629.80 630.00 0.00 0.00 Weir Type = Riser Rect - - Length(ft) = 41.50 0.00 0.00 0.00 Multistage = Yes Yes No No Slope(%) = 0.83 0.00 0.00 0.00 N-Value = .026 .026 .013 .000 Orif.Coeff. = 0.80 0.60 0.60 0.00 Multi-Stage = n/a Yes No No ExfiItration= 0.000 Inihr(Contour) Tailwater Elev.= 0.00 ft Note:Culvert/Oriflce outflows have been analyzed under Inlet and outlet control. Weir riser checked for orifice conditions. Stage(ft) Stage/Discharge Stage(ft) 6.00 6.00 5.00 . 5.00 - __ - 4.00 - ----- 4.00 3.00 3.00 2.00 -- - 2.00 1.00 - 1.00 0.00 0.00 0.00 3.00 6.00 9.00 12.00 - 15.00 18.00 21.00 24.00 27.00 30.00 1 - Total Q Discharge(cfs) 1 DRAINAGE AND SEDIMENT CONTROL CALCULATIONS FOR WESTHALL PHASE I & II PREPARED BY ILO Agl. ih" ENGINEERS SURVEYORS PLANNERS ASSOCIATES 1402 Greenbrier Place Charlottesville, Virginia 22901 (434)984-2700 December 21, 1005 (Revised) Project Number: 204208.03 �14 ' r O ioJf4fr' (. DAVID M.JENSEN �Y No. 1148 Reviewed and Approved by the Community Development Deparbuent Cs SSG Date: /e cam. 2caeg, File#: >io t8ue .--• Design Calculations WW# 204208.08C Table of Contents A. Drainage B. Erosion and Sediment Control STORM SEWER DE COMPUTATIO^ I AREA RUN- FROM TO DRAIN OFF TOP INLET INLET DEPTH INLET No. POINT POINT "A" COEF REMARKS ELEVATIONS (H) ACRES C INCRE FT FT MEN-1 (1) (2) (3) (4) (5) 1 (19) (20) (21) (22) 0 1 5.04 0.730 3.681 DI-1 644.00 7.75 0 1 2 0.29 0.730 0.21, DI-30 644.86 9.20 1 2 3 0.27 0.730 0.201 DI-3C 644.86 9.93 2 3 3A OUTLETI MH 646.41 13.32 3 4 5 0.15 0.733 0.111 DI-3B 642.85 6.50 4 5A 5 0.31 0.400 0.121 D1-1 637.25 4.00 5A 5 6 0.24 0.750 0.18E DI-3C 642.07 9.28 5 6 6A OUTLET 0.19 0.737 0.14; DI-3B 642.17 9.94 6 7 8 0.11 0.727 0.081 DI-30 648.23 6.57 7 8 9 0.19 0.579 0.111 DI-3C 648.29 7.14 8 9 10 1 MH 641.75 5.00 9 10 11 0.57 0.263 0.151 DI-3B 638.58 5.00 10 11 12 0.22 0.591 0.131 DI-3B 638.52 5.43 11 1 12 12A OUTLET i MR 635.00 3.50 12 1 13 14 0.10 0.700 0.071 DI-3B 631.57 6.44 13 14 15 1.00 0.470 0.471 DI-38 631.63 6.98 14 I 15 16 1.06 0.491 0.521 DI-3C 623.40 6.44 15 16 16A MH 621.57 10.22 16 - 16A 17 MH 612.79 4.79 16A 17 17A OUTLET MH 570.00 6.12 17 18 18A 0.57 0.702 0.40i DI-3C 615.15 8.01 18 18A 19 I MH 607.00 4.20 18A 19 19A OUTLET MH 568.00 3.80 19 • Temporary Sediment Basin Design Data Sheet Project Westhall Phase I&II (without Emergency Spillway) Basin# "C" Location Draw between Nicolet Ct&Park Rd. Total area draining to basin 4.59 acres. Basin Volume Design Wet storage: 1. Minimum required volume=67 cu. yds.x total drainage area(acres) • 67 cy.x 4.59 acres= 307 cy. 2. Available basin volume= 307 cy. at elevation_c o 55 • From storage-elevation curve 3. Excavate 307 cy.to obtain required volume. • Elevation corresponding to required volume = invert of the dewatering orifice. 4. Available volume before cleanout required. • 33 cy.x 4.59 acres= 151 cy. 5. Elevation corresponding to cleanout level= 56R.40 • From storage-elevation curve 6. Distance from invert of the dewatering orifice to cleanout level= 1 15 ft. • Min.= 1.0 ft. Dry storage: 7. Minimum required volume=67 cy.x total drainage area(acres). • 67 cy.x 4.59 acres= 307 cy. 8. Total available basin volume at crest of riser= 615 cy at elevation 571.70 • From storage-elevation curve • Minimum= 134 cy./ac. of total drainage area. 9. Diameter of dewatering orifice= 3" in. 10. Diameter of flexible tubing= 5" in. • Diameter of dewatering orifice+2 in. Q=S/21,600 Preliminary Design Elevations Q=4212 c.f./21,600 Seconds 11. Crest of riser= 571.70 Q=0.2 cfs Top of dam= 574.55 H=(571.70-569.50)/2=0.6 Design high water= 572.55 A=0.2 Upstream toe of dam= 567.00 0.6[(64.32)(0.6)]0 0.5 .5 - 12. L=length of flow;We=effective width L = 100 We =1.7 We=A=5800S.F.=58 58 L 100 • If>2,baffles are not required❑ • If<2,baffles are required n Runoff 13. Q2= 20 cfs (from Chapter 5) 14. Q2= 22 cfs (from Chapter 5) Principal Spillway Design 15. With emergency spillway,required spillway capacity Qp =Q2 = 20 cfs • riser and barrel (4.59)(0.60)(7.1)=20 cfs Without emergency spillway,required spillway capacity Qp =Q25 = 22 cfs • riser and barrel (4.59)(0.60)(8.1)=22 cfs 16. With emergency spillway: Assumed available head (h) = N/A ft. • Using Q2; h=emergency spillway elevation—crest of riser elevation Without emergency spillway: Assumed available head (h) = 0 R4 ft. • Using Q25; h=design high water elevation—crest of riser elevation 17. Riser diameter (0= 36 in.;Actual head (h) = o R4 ft. • From Plate 3.14-8 • Note:Avoid orifice flow conditions. 18. Barrel length (i)= 35 ft. Head (H) on barrel through embankment 8.55 ft. • From Plate 3.14-7 19. Barrel diameter= 21 in. @ 35'length &8.55'=H ;Q=23.3 cfs(corrugated pipe) • From Plate 3.14-B (concrete pipe)or Plate 3.14-A (corrugated pipe) 20. Trash rack and anti-vortex device Diameter= 54 in. Height= 17 in. • From Table 3.14-D Emergency Spillway Design N/A 21. Required spillway capacity QQ =Q25 —Qp = cfs. 22. Bottom width (b) = ft.; Slope of exit channel (s) = ft.; Minimum length of exit channel (x) = R. • From Table 3.14-C Anti-seep Collar Design N/A <10 feet in height 23. Depth of water at principal spillway crest (1'1 = ft. Slope of upstream face of embankment (Z) = ft. Slope of principal spillway barrel (Sb) = Length of barrel in saturated zone (L3) = ft. 24. Number of collars required= : dimensions= • From Plate 3.14-12 Final Design Elevations 25. Top of dam= 574.55 Design high water= 572.55 Emergency spillway crest= N/A Principal spillway crest= 571.70 Dewatering orifice invert= 569.55 Cleanout elevation= 568.40 Elevation of upstream toe of dam or excavated bottom of wet storage area (if excavation was performed)= 567.00 1992 • • 3.14 moo : , H .• I • I� i�n�llll B°° Riser Inflow Curves • 60O 1 11111111111 Legend s0o __.____ __ _}-Neir-floa.-QK•9.739-0rFt3�Z 1 �`— ---•- Orifice flue, Q, 3.782 0'0 It IiUHN"H 300 • �fl . -''- fl I I liff11 : - , I NI1.4141l Jf VP j iiiii.iiiiiiiit Os 20 ' [vP;2 40,rgi%rlii t'S: :-7.i 6 mumononq.lili N r fir.GO �. cps __ :_ . _ Fir:%1p1: _etl'C Iiiiiii1i111111 • Ap '� 61 h' . `. ' lilililliT B _ .uuiI ; •I' •6 . , . iii 1/ ; ' 1 I I • !I 3 prfl?,111.1111,1111.1 _ IIS1i1111i!l11111 . . ,i/A.y. A • 11- IPIllr: IriliAlPAE°111511.1111E q .i`iiiiiiii . • .1` [°;' ' • - . . 1. .11 ,. :�' � f,=! ti . 7 mg==i0■ 1111111 DI. 02 03 QII 06 .• ID 2.0 ' 3D 40 6D 6D 8D IOD IW hint, mn.na Item nest ai Nur • Source: USDA-SCS • F! 'Or 85 ' • , _1 Plate 3.14-8 3(ali RTSER • m nn 1 • • TABLE 3.14-A • • PIPE FLOW CHART, n = 0.025 N f0n com00019 f0:TBL P731 1121711 fq• fie+ Et• 1.0 AND 70 FEET Of W1900070 KOHL PIPE 01tl00sr Kull flaw eesomodl • Dote correction Canton for pipe langtW otlev than 70 feet ydj17r•4 dlemtes of floe 1n inches VV 0. _ . fact 8' 8" 100 12" 15" 1B• 21" 24" 30• 36• 4 " 48' 54• 60• 66" 72' 70• tl4• 90" 96" 302" .....lit 1 0.23 0.70 1.25 1.98 3.40 5.47 7.99 11.0 18.8 28.8• 41.1 71.6 91. 1 191 R21 25S 290 2 0.47 0.99 1.76 2.80,.,4.97 74 11.3 15.6 26.6 40.0 58.2 78.8 103 170 160 194 • 231 271 314 360 410 • y 3 0.50 1.12 2.16 3.43 6.02. AO,13.0 19.1 32.6 49.9 71.2 96.5 126 159 196 237 202 771 304 441 • 502 4 0.67 1.40 2.49 3.97 6.95 1 .9 16.0 22.1 37.4 57.7 82.3 111 145 104 236 274 326 ]9] 441 510 500 5 0.74 1.57 2.79 4.43 7.78 1 .1 ' 17.9 2417 4575 64.5 93.0 125 162 200 253, 306 365 328 496 570 640 6 0.02 1.72 3.05 4.06 8.52 U. 10.6 27.0 46.1 70.6 101 136 170 225 277 336 399 469 544 624 710 7 0.88 1.06 7.30.S.25 9.20 14. 21.1 29.7 49.8 76.3 109 147 192 243 300 362 431 506 587 674 767 8:59 0.99 1.99 ].9] S.fil 9.B1 19.5 # 6 ]2.] 83.7 81.5 116 1S8 205 7fi0 320 308 461 541 628 721 830 1.00 2.11 3.74 5.05 '10.4 16.1 21.0 33.1 56.4 06.5 173 167 218 375 340 411 469 574 666 764 870 10 1.05 2.22 3.94 6,27 11.0 17.3 25.3 34.9 59.9 91.2 130 176 230 290 350 433 516 605 702 006 917 • 11 1.10 2.33 4.13 6.50 11.5 10.2 26.5 26.6 62.4 95.6 136 105 241 304 • 376 454 541 635 736 045 P62 U 1.15 2.43 4.32 6.07 12.1 10.0 27.7 30.2 65.2 09.9 142 193 7.52 318 392 475 565 663 769 683 1004 13 1.20 2.53 4.49 7.15 12.6 19.7 20.0 39.0 67.0 104 140 201 262 231 408 . 494 508 690 800 919 1045 14 1.29 2.63 4.66 7.42 1.0 20.5 29.9 41.3 70.4 109 154 208 272 341 424 513 • 610 716 630 953 105 15 1.29 2.72 4.87 7.68 U.S 31.2 70.9 42.8 72.8 112 159 218 201 755 479 531 631 741 860 987 1113 ' , 16 1.33 2.81 4.99 7.93 13.9 21.9 72.0 44.2 75.2 11S '165 223 290 . 367 •453 540 ' 652 765 000 1019 1160 17 1,37 2.90 5.14 0.18 14.3 72.6 32.9 45.5 77.5 119 • 170 230, 229 778 467' 565 .672 789 915 1051 1195 W) 10 1.41 2.98 5.29 0.41. 11.0 23.2 33.9 46.0 70.8 120 17.1 936 308 309 ' 400 581 697 812 942 1001 1239 19 1.45 3.06 5.43 8.64 112 23.9 34.8 48.1 02.0 126 „179 243 316 400 , 494 ,•597 711 034 967 1111 I 1264 20 1.49 7.14 5.57 0.07 15.6 24.5 39.7 49.4 64.1 129. ' 184 249 • 71S • 410 506 613 729 056 993 1199.1 1297 21 1.53 7.22 5.71 9.09 15.9 25.1 36.6. 50.6 86,2'132 ISO •255 ' 323 421' 519 678 747 677 1017 1168 1329 22 1.56 7.29 5.85 9.30 16.3 25.7 77.5 51.0 '88.1 135 193•.: 269 . • 741 430 531 643 765 090 1041 1195 1360 71 1:60 3.37 5.98 9.51. 16.7 21.2,4'36.3 53.0' 10.2 118 . 197. • 267 348 440 543 657 702 918 104 1222 1390 '24 1.63 1,44 6.11 9.72 17.0 . 26.0 79.1 54.1 ':92.1 .141 201' 273 356 . 450 555 611 799 937 1007 1240 1420 , 25 1.66 3.51 6.23 9.92 17.4• -27.4 '79.9 55.2 •'94.0 '145 ' 206 279 . 363 469 566 605 BU 957 '%1110 1274 1450 ,. .26 1.70 3.58 6.36 10.1 17.7 27.9 .40.7, 66.3 95.9•'147 110 204 370 468 577 •699 021 976 1132 1299 1478 • 37 1.77 3.65, 6.48 10.1 18.1 .28.4 41.5 57.4 97.1 150 214 290 377 I .477 • 588 712 847 994 1153 1324 1507 • 18 1.76 3.72. 6,60 10.5 .10.4 29.9 42.3 58.4 99.5 153 218 ' 295 394 466 599 ' 725 0631013 1174 1340 i 1534 129 1.79 3.78.•6.71.10.7 1847 •29.5 •'.43.0. ' 59.5 101 155 221 300 391 494 610 ' 738 870 1070 1195 1372 1 1561 • 30 1.02, 7.85 6.83 10.9', 19.1 30.0 13.7 60.6.103 19B 225 705 798 503 610 750 893 1040 1216 196 I 1558 • L. in ., •.. Correction Factors For Other Pipe Lengths • ' • jest - y - • , 20 1.69 1.62 1.50 1.51 1.47" 1.42 1.77 ' 1.34 1.20 1-14 1.20 1.10 1.16 1.14 1.13 1.11 1.10 1.10 1.09 1.08 1.00 , (ale 1.44 1.61 1.79 1.36•'1.12 1.29 .27 1.24 1.21 1 10 . 1.15 1.13 1.12 1.11 1.10 1.09 1.00 7.07 1.07 1.06 1.06 3 40 1.28 1.5, 1.25 123 1.21 1.20 1.10 117 1.14 1 12 1.11 1.10 1.09. 1.08 1.07 1.06 1.06 1.05 1.05 1.05 1.04 50 1.16, 1 16 1.10 1.14 1.13; 1.12 1.11 •1.1v 1.09 1 0B 1.07• 1.06 1.06 1.05 1.05 1.04 1.04 1.02 1.02 1.03 1.07 60 1.07'1.0 1.07 1.08 1.06' •1.05 '1.05 1.05 1.04 1 04 1.03 1.03 1.03 ' 1.02 '1.02 1.02 ' 1.02 1.01 1.02 1.02 1.01 90 1.00 1.00 1.00 1.00 .1.00 1.05 1.00 1.00 1.00 1 00 1.00 1.00 1.00 ' 1.00 1.00 1:00 1.00 1.00 1.02 1.00 . 1.00 • . 80 .94 '.94 .95 .95 .95 .95 .96 •.96 .96 97 .97 .97 .98 .98 .98' .90 .90 .98 .99 .99 • .99 . • 90 .09 .89 .90 ..90 .91 .91 .92 .97 .93 94 .94 .95 . .95 .96 . .96 .96 .97 .97 .97 .97 ' .94 100 .85 .85 .86 .66 .07 .00 .09 .09 .90 91 .92 .97 .03 .94 .94 .85 .95 .0 .96 .96 .94 • • 120 .78 .79 .79' .90 .01 .02 .97 .97 .05 86 .07 . .89 .09 .90 .91 .89 .92 .97 .93 .94 .92 ' • 140 .72 .73 .74 .75 .76 .77 .78 .79 .e1 62 .84 .85 .06 .87 .88 .02 .89 .90 .91 .91 .90 160 .68 .69 .69 .70 .71 .73 .74 .75 .77 79 .00 .02 .03 .84 .05 .92 .07 .08 .89 .09 4N • .. . .. . . . l'ZZ .. . . . . 1' I. I { f t `% , / p I • is ANTI- VORTEX DEVICE DESIGN p PRESSURE RELIEF • ice. HOLES 1/7 DIA. Tr �• . O NIA y A ! • 1A O ' O TOP STIFFENER (IF REQUIRED) Lill TO TOP AND GLE E LDED PER- - TOP AND ORIENTED PER- : O . 0 PENDICULAR TO CORRUGATIONS. TOP IS±GAGE CORRUGATED 04110,0 1000;100 METAL OR 1[B° STEEL PLATE. PRESSURE REELIEF HOLES MAY IBE OMMITTED, IF ENDS OF I ' CORRUGATIONS ARE LEFT FULLY p PLAN VIEW OPEN WOEN THE TOP IS w TACKY&LI) a IED CYLINDER IS�GAGE CORRUGATED ALL AROUND ' '=g'-''"".:..'r-,3`_. :,--r."= ' `= �v`�"' METAL PIPE OR FABRICATED FROM .. .� .µ:,.�. re � `-" ��', 8" -_.... _.-_. _a_. .... ... H STEEL PLATE. Atilt llluiF:.�li rl:nr�iTaltaiiil?Itf:uit�`nlfi gum. • )1...a - ^4i""s sue! •- .. NOTES: ,!5, '�3_'yam uz.'r--"Sn' �'�..*_xz_• N'10' D' MIN. • `k y ^tt r I. THE CYLINDER MUST BE 'Finany- FIRMLY FASTENED, TO THE r:-.ems.° '%3:."' '..,4'^ y ' • a }� e, TOP OF THE RIS IR.• fie X 7Y "^ --• ' x'-� SUPPORT 6AR SIZE 2. SUPPORT BARS ARE WELDED SPACER DAR � E'--„'" ,li.�. (Q8 REBM MIN.) TO THE TOP OF THE RISER Y,L'.T ,•_ OR ATTACHED BYE STRAPS P • I• FUSER DIAMETER : I • L BOLTED TO TOP OF RISER. w P • SECTION A-A ISOMETRIC w • 1992 •3.14 TABLE 3.14D CONCENTRIC TRASH RACK AND ANTI VORTEX DEVICE DESIGN TABLE E _ -- -_Riser__ Cylinder - - . Minimum Top Dian., Height, Minimum Size in Diameter, Thickness, inches Support Bar Thickness Stiffener inches - gage. 12 18 16 6 #6 Reber or11hx 16ga. - 1*h x 3/16 angle (F&C) 15 21 . 16 7 ' ' " " - 18 27 16 8 " ' " " 21 30 16 •.. 11 " " 16 ga.(C), 14 - g;a(F) • 24 36 16 •13 . . . • " '" 27 ' 42 16 - IS " " " " - . 36 54 14 17 #8 Reber 14 11 - . ga(F) 42 60 • 16 - 19 " • . " - •48 72 16 21 11A"pipe or 114 x 14 ga.(C),10 - C, r,p Ws x+/4 angle ga.(e •`/ 60 90 e 14 29 1St"pipe or 114 x 12 ga.(C),8 - 11/2 x IA angle ga(F) 66 96 . 14 33 _ 2"pipe or2x2x 12ga(C), 8 2x2xIA 3/16 angle ga.(F) angle ' w/stiffener. 72 • 102 14' 36 " " . " 21/2 x 2'h x • IA angle 78 • 114 ' 14 39 .216"pipe or 2 x 2 x " " " • • - . '/a angle 84 120• • 12 . 42 21/2" pipe or 2'h x " " • ?IA x 21&x 21h x IA angle 5/16 angle Note1: The criterion for sizing the cylinder is that the area between the inside of the cylinder and the outside of the riser is equal to or greater than the area inside the riser. Therefore, the above table is invalid for use with concrete pipe risers. Note2.-Corrugation for 121-36e pipe measures 224511 x'h";for 42"-84"the corrugation measures 5"x 1" or 8"x 1"• - Note3: C = corrugated; F = flat. . Source: Adapted from USDA SCS and Carl M.Henshaw Drainage Products Information. � III - 104 • • l