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Home My WebLink About56 Welsh Office Park CSISD 00-2 1812 Welsh~-v DEVELOPMENT PERMIT PERMIT NO. 500002 COLUGl STATION DP-CSISD MAINT. BLDG PARKING ADDITION FOR AREAS OUTSIDE THE SPECIAL FLOOD HAZARD AREA RE: CHAPTER 13 OF THE COLLEGE STATION CITY CODE SITE LEGAL DESCRIPTION: DATE OF ISSUE: February 25, 2000 OWNER: COLLEGE STATION ISD 1812 WELSH #120 COLLEGE STATION, TX 77840 SITE ADDRESS: 1812 WELSH AVE DRAINAGE BASIN: BEE CREEK VALID FOR 12 MONTHS CONTRACTOR: TYPE OF DEVELOPMENT: CONSTURCTION AS PER APPROVED PLANS SPECIAL CONDITIONS: NIA The Contractor shall take all necessary precautions to prevent silt and debris from leaving the immediate construction site in accordance with the approved erosion control plan as well as the City of College Station Drainage Policy and Design Criteria. The Owner and/or Contractor shall assure that all disturbed areas are sodden and establishment of vegetation occurs prior to removal of any silt fencing or hay bales used for temporary erosion control. The Owner and/or Contractor shall also insure that any disturbed vegetation be returned to its original condition, placement and state. The Owner and/or Contractor shall be responsible for any damage to adjacent properties, city streets or infrastructure due to heavy machinery and/or equipment as well as erosion, siltation or sedimentation resulting from the permitted work. Any trees required to be protected by ordinance or as part of the landscape plan must be completely fenced before any operations of this permit can begin. In accordance with Chapter 13 of the Code of Ordinances of the City of College Station, measures shall be taken to insure that debris from construction, erosion, and sedimentation shall not be deposited in city streets, or existing drainage facilities. I hereby grant this permit for development of an area outside the special flood hazard area. All development shall be in accordance with the plans and specifications submitted to and approved by the City Engineer in the development permit application for the ed project and all of the codes and ordinances of the City of College Station that apply. Date Z-2-s-oo Date Contractor Date • r ( I ( ·-.. ~( . r ~ ~ , I ' 11 /02 '00 11:03 FAX 409 693 4243 M D G MUNICIPAL DEVELOPMENT GROUP 2551 Texas A ve . Sou th, S te. A • ~o/lege Station, Texas 77840 • 409 693 -5359 •FAX: 409 693-4243 •E-mail: mdgcs@gte.com December 30, 1999 Jeff Tondre City of College Station Development Services PO Box9960 College Station, Texas 77842 RE: Drainage Letter-CISID Maintenance Facilities MDG Job No. 000737-3262 Dear Jeff: The above referenced project consist of constructing 23 new spaces at the existing CSISD Maintenance Facility. This parking lot will be constructed with an H .M.A.C. surface with pertinent base and subgrade. The project site is located to the rear of the administration building on a 5.70 acre-tract. The project site is located immediately upstream of the Bee Creek Tributary B and does not contain floodplain or floodway as graphically depicted by F .E.M.A. F .I.RM. Community Panel No. 48041COl44C (July 2, 1992). Using the Rational Method {Q=CIA), the parking lot improvements will create the following runoff increases: RUNOFF CALCULATIONS Storm (Yr) Pre (cfs) Post (cfs) Diff. (cfs) Req'd Detention (ft3) 2 1.562 3.123 1.561 1405 5 1.899 3.798 1.899 1709 10 2.131 4 .263 2 .132 1918 25 2 .434 4.868 2.434 2191 50 2 .752 5.503 2 .751 2477 100 2.873 5.746 2.873 2586 The policy of the City of College Station is to encourage the rapid conveyance of storm water through and out of the City w ithin the primary system. Since this project site is near the confluences of Bee Creek, being a primary system, no runoff will be detained on the site and the post-development runoff will discharge directly, without constriction, to the drainage channel that drains to Tributary B of Bee Creek. This is done in order to keep from stacking peaks of the primary creek and the discharge of the site runoff and will remain consistent with the drainage pattern of the current facilities. 000737-c.Q)-73(3262) ~002 11 /02 '00 11 :03 FAX 409 693 4243 M D G Justification of no detention was made by the comparison of time on concentration, (Tc) of both hydrographs . The approximate Tc of Tributary B of Bee Creek, to the project site, is approximatelytwenty- five minutes . This Tc assumes and average velocity of 3.0 ft/sec and a travel distance of 6300 feet . The minimum Tc of the site allowed without detention is ten minutes. With detention, the Tc of the site increases to approximately twenty minutes. Therefore, detention on-site would potentially increase the overall peak of Bee Creek Tributary B. In conclusion, the basic design of the drainage improvements will include: • No on-site detention with direct discharge into drainage channel to Tributary B of Bee Creek; • Discharge of parking lot runoff through into existing drainage channel; • Implementation of standard erosion control devices . Please call me if you have any questions . ~~.-aM~ North B . Bardell, Jr., P.E. C.E.O., Project Manager 000737-c .03· 73(3262) -...::· ~003 11 /02 '00 11:03 FAX 409 693 4243 M D G SECTION #2 CMINORl -PRE-DEVELOPMENT GENERAL INFORMATION Description: Drainage area of site before development. Drainage Area (ApRe) = 0.544 acres TIME OF CONCENTRATION CT,J GIVEN Maximum Travel Distance (DPREl Velocity of Runoff (VpRi:) = Coefficient of Runoff (CpRe) = 100 ft ft 0.75 l,ec 0.45 -NOTE: Minimum Tc allowed= 10 min. 2 YEAR FREQUENCY. RATE OF DISCHARGE (Q) Coefficient (e) = 0.606 Coefficient (b) = 65 Coefficient {d) = 6 5 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e) = 0.765 Coefficient (b) = 76 Coefficient (d) = 8.5 10 YEAR FREQUENCY. RATE OF DISCHARGE (Q) Coefficient {e) = 0.763 Coefficient (b) = 80 Coefficient (d) = 8.5 25 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e) = Coefficient (b) = Coefficient (d) = 0 .754 89 8.5 50 YEAR FREQUENCY. RA TE OF DISCHARGE CO> RESULT Tc(PRE) = Rainfall Intensity {Ii} = Rainfall Intensity {1 5) = Rainfall Intensity (1 10) = Rainfall Intensity (1 25 ) = Coefficient (e) = 0.745 Rainfall Intensity (1 5o) = Coefficient (b) = Coefficient (d) = 98 8.5 100 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e) = 0. 73 Coefficient (b) • 96 Coefficient (d) = 8 000737-3262 Drainage Calculations.xis Rainfall Intensity (1 100) ~004 2.2 min. 8.635 In/hr 11 /02 '00 11 :03 FAX 409 693 4243 M D G SECTION #3 CMJNORl -POST-DEVELOPMENT GENERAL INFORMATION Description: Drainage area of site after development Drainage Area (A 1) = 0.544 acres (impervious area) Drainage Area (A.;J = 0.000 acres (landscaped area) TIME OF CONCENTRATION CT,.) GIVEN Maximum Travel Distance (D,) = Velocity of Runoff 0/1) = Coefficient of Runoff (C,) = Maximum Travel Distance (D2) = Velocity of Runoff 01.;J = Coefficient of Runoff (C 2) = 100 ft 2.00 "lsec 0.90 0 ft ft. 2.00 lsec 0.45 **NOTE: Minimum Tc allowed= 10 min. 2 YEAR FREQUENCY. RATE OF DISCHARGE {Q) Coefficient (e) = Coefficient (b) = Coefficient (d) = 0 .806 65 8 5 YEAR FREQUENCY. RATE OF DISCHARGE CO) Coefficient (e) = 0.785 Coefficient (b) = 76 Coefficient (d) = 8.5 10 YEAR FREQUENCY. RATE OF DISCHARGE (Q) Coefficient (e) = Coefficient (b) = Coefficient (d) = 0.763 80 8.5 25 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e) = Coefficient (b) = Coefficient (d) = 0.754 89 8.5 50 YEAR FREQUENCY, RATE OF DISCHARGE (Q) Coefficient (e) = Coefficient (b) = Coefficient (d) = 0 .745 98 8 .5 100 YEAR FREQUENCY. RATE OF DISCHARGE (Q) Coefficient (e) = Coefficient (b) = Coefficient (d) = 000737-3262 Drainage Calculations.xis 0.73 96 8 RESULT TC2 = TqPOST) = Rainfall Intensity (l.;J = QAREA 1: QAREA2 = Rainfall Intensity (1 5) = QAREA 1 = QAREA2: Rainfall Intensity (1 10) = QAREA 1: QAREA2: Rainfall Intensity (1 25 ) = QAREA 1: QAREA2: Rainfall Intensity (1 50) = QAREA 1: QAREA2: Rainfall Intensity (l,00) QAREA1: QAREA2 = 0.8 min . 0.0 min. 0.8 min . 6 .327 in/hr 3.123 cfs o.ooo cfs 7.693 in/hr 3.798 cfs 0.000 cfs 8.635 in/hr 4 .263 cfs 0 .000 cfs 9 .861 in/hr 4 .868 cfs 0.000 cfs 11.148 in/hr 5.503 cfs 0.000 cfs In/ 11.639 hr 5 .746 cfs 0.000 cfs ~005 11 /02 '00 11 : 03 FAX 409 693 4243 M D G SECTION #4 -HYDROGRAfHS Chart 4 2:. YEAR HYl)ROGRAPH Volume Con eyed 0 10 II Post-Development ID Pre-Development HYDROGRAPHS Chart 4 1,405 ft3 TIME (min) 20 ~006 30 11 /02 • 00 11:03 FAX 409 693 4243 M D G . SECTION #4 -HYDROGRAPHS Chart 5 5-YEAR HYDROGRAPH 3---------- -~ u - 2------- 1 0 0 10 II Post-Development El Pre-Development HYDROORAPHS Chart S TIME (min) 20 ~007 30 11 /02 '00 11 : 03 FAX 409 693 4243 M D G SECTION #4 • HYDROGRAPHS Chart 6 10-YEAR HYDROGRAPH 5..----------------------------------...-------------------------------....... ------------------------------~ 4------------- Volume Convey 3----------- -~ v - 2------ 1 0 10 II Post-Development t!1 Pre-Development HYDROGRAPHS Chart 6 TIME (min) 20 30 ~008 11 /02 '00 11 : 03 FAX 409 693 4243 M D G SECTION #4 -HYDROGRAPHS Chart 7 25-YEAR HYDROGRAPH 0 10 Ill Post-Development Im Pre-Development HYDROGRAPHS Chart 7 TIME (min) 20 ~009 30 11 /02 • 00 11 : 03 FAX 409 693 4243 M D G SECTION #4 -HYDROGRAPHS Chart 8 50-YEAR HYDROGRAPH Volume Conveyed s------------- 4..---------- 2..----- 1 0 10 II Post-Development El Pre-Development HYDROGRAPHS Chart 8 TIME (min) 20 ~010 30 11 /02 • 00 11: 03 FAX 409 693 4243 M D G SECTION #4 -HYDROGRAPHS Chart 9 100-YEAR HYDROGRAPH 10 Volume Conveyed 2,586 ft 3 8--------------- 7 ------------ s---------- 5---------- 4------- 3----- 2--- 1 0 10 m Pre-Development II Post-Development TIME (min) HYDROGRAPHS Chart 9 20 ~011 30 CAS£ ;,o.:5Db -00:2 I DA TE SUBMITTED: } ~/ 3 O /q q DEVELOPMENT PERMIT ML'fIMUM SUBMITTAL REQUIREMENTS N/t::,.. .$100.00 Development Permit Application Fee. /Drainage and erosion control plan, with supporting Drainage Report two (2) copies each. ~Notice ofintent (N.O.I.) if disturbed area is greater than 5 acres. APPLICANT (Primary Contact for the Project): Name Mt>N\C\.PAL DE\/eL.DPMt:N1 fu.e\J'f Street Address 29?" I TOA~ A--iE. $.) S;c., A LY\tt:Grj-~~ VV1E-tOH.f city _....;:;c_.s...:......;_. ________ _ State Tu Zip Code 7781-lb E-MailAddress rod.~c!:> @ 'jtc..ne..t- Fax Number Co'1'b-Y Z:< ~ Phone Number (o0 l'b-S'?'S°\ PROPER1Y OWNER'S INFORMATION: . Name co~t..E:.f;«. S:v\110N :r .5 ,'Q. Street Address I 'e>\Z. W~1..~t~ .S-r . City -~C_._S___;,_. ________ _ State TX. Zip Code ( 73Y. c E-Mail Address ------------- Phone Number @y -5 w I 't> Fax Number _ __.(p""""<J-'--"tj._-_5=-c(o=--:-\ C.-=------------ ARCHITE CT OR EJ\TGTNEER'S INFORlVfATION: Name ?:, N'lA:;. bS ~of l A cA:NI · Street Address -----------------City -------------- State Zip Code ______ E-Mail Address ------------- Phone Number Fax Number ------------------ Application is hereby made for the follov•,ing development specific site/watezway alterations: YA'Lf.1Nk l-tn ) JY)\f'r2.ti\f~'{(.cl"1S \~ -njts ~ c~ ~~'f:z-'Prv11~ N. ACKNOWLEDGMEJ\'TS: I, J;1.,, V I 'O ~AL , design engineer/owner, hereby acknowledge or affirm that: The information and conclusions cont.1incd in the above plans and supporting documents comply \vith the current requirements of the City of C ollege St:it ion, Texa s City Code , Chapter 13 and its associated Drainage Poli cy and Design Standards . As a condi tion of approval of this pem1it application, I agree to construct the improvements proposed in this application ac rding to these documents and the requirements of Chapter 13 of the College Station City Code . DEVELOP\IE:"T PER.\l!T DPf::R\HT TX-': :: :~'99 N/A Contractor ton ~ . CERTIFICATIONS: (for proposed alterations within designated flood hazard areas .) A. I, ~A , certify that an y nonresidential structure on or proposed to be on this site as part of this application is designated to prevent damage to the structure or its contents as a result of flooding from the 100 year storm. Engineer Date B. L N/A , certify that the finished floor elevation of the lowest floor, including any basement, of any residential structure, proposed as part of this application is at or above the base flood elevation established in the latest Federal Insurance Administration Flood Hazard Study and maps, as amended. Engineer Date C . L NoL·n\ ~. ~;Ji.{.~, certify that the alterations or development covered by this permit shall not diminish the flood-carrying capacity of the waterway adjoining or crossing this permitted site and that such alterations or development are consistent with requirements of the City of College Station City Code, Chapter 13 concerning achrn nts of flo vavs and of floodwav frim~es. B. . . -~ z~ N1~ Date D . I, N/A do certify that the proposed alterations do not raise the level of the 100 year flood above elevation established in the latest Fed eral Insurance Administration Flood Hazard Study. Engineer Date Cond itions or comments as part of approval : ---------------------------- In accordance \vi th Chapter 13 of the Code of Ordinances of the Ci ty of College Station, measures shall be taken to insure that debris from construction , erosion, and sedimentation shall not be deposited in city streets , or existing drainage facilities . All development shall be in accordance with the plans and specifications submitted to and approved by the City Engineer for the above named proj ect. All of the applicable code s and ordinances of the City of Coll ege StJ.t ion shall apply . DE\"ELOP .\fE:~I PER.\!lT DP EP...'.f!T 'YJC 3 '2.! 9 9 ::? of2 MUNICIPAL DEVELOPMENT GROUP 2551 Texas A ve . South , Ste . A •College Station , Tex as 77840 • 409 693-5359 •FAX: 409 693-4243 •E-mail: mdgcs@gte.com Consulting Engineers , Survey ors , Planners and Environmental Consultants December 30, 1999 Jeff Tondre City of College Station Development Services PO Box 9960 College Station, Texas 77842 RE: Drainage Letter -CISID Maintenance Facilities MDG Job No. 000737-3262 Dear Jeff: The above referenced project consist of constructing 23 new spaces at the existing CSISD Maintenance Facility. This parking lot will be constructed with an H.M.A.C. surface with pertinent base and subgrade. The project site is located to the rear of the administration building on a 5.70 acre-tract. The project site is located immediately upstream of the Bee Creek Tributary B and does not contain floodplain or flood way as graphically depicted by F.E.M.A. F .I.R.M. Community Panel No. 48041CO144C (July 2 , 1992). Using the Rational Method (Q=CIA), the parking lot improvements will create the following runoff increases: RU NOFF CALCULATIONS Storm (Yr) Pre (cfs) Post (cfs) Diff. (cfs) Req'd Detention (ft3) 2 1.562 3 .123 1.561 1405 5 1.899 3.798 1.899 1709 10 2 .131 4 .263 2 .132 1918 25 2.434 4 .868 2.434 2191 50 2 .752 5.503 2 .751 2477 100 2 .873 5 .746 2 .873 2586 The policy of the City of College Station is to encourage the rapid conveyance of storm water through and out of the City within the primary system. Since this project site is near the confluences of Bee Creek, being a primary system , no runoff will be detained on the site and the post-development runoff will discharge directly, without constriction , to the drainage channel that drains to Tributary B of Bee Creek. This is done in order to keep from stacking peaks of the primary creek and the discharge of the site runoff and will remain consistent with the drainage pattern of the current facilities . 000737-c.03 -7 3(3 262) Justification of no detention was made by the comparison of time on concentration, (Tc) of both hydrographs . The approximate Tc of Tributary B of Bee Creek, to the project site, is approximately twenty- five minutes . This Tc assumes and average velocity of 3 .0 ft/sec and a travel distance of 6300 feet. The minimum Tc of the site allowed without detention is ten minutes. With detention, the Tc of the site increases to approximately twenty minutes. Therefore, detention on-site would potentially increase the overall peak of Bee Creek Tributary B. In conclusion, the basic design of the drainage improvements will include: • No on-site detention with direct discharge into drainage channel to Tributary B of Bee Creek; • Discharge of parking lot runoff through into existing drainage channel; • Implementation of standard erosion control devices . Please call me if you have any questions. Sincerely, North B . Bardell, Jr., P.E. C.E.O ., Project Manager 0007 37-c.03-73(32 62) SECTION #2 (MINOR) -PRE-DEVELOPMENT GENERAL INFORMATION Description : Drainage area of site before development. Drainage Area (A PR E) = 0.544 acres TIME OF CONCENTRATION CT c) GIVEN Maximum Travel Distance (D PR E) Velocity of Runoff (VPR E) = 100 ft ft 0.75 f sec Coefficient of Runoff (CpRIJ = 0.45 **NOTE : Minimum T c allowed = 10 min . 2 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e) = Coefficient (b) = Coefficient (d) = 0.806 65 8 5 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e) = 0 .785 Coefficient (b) = 76 Coefficient (d) = 8.5 10 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e) = 0 .763 Coefficient (b) = 80 Coefficient (d) = 8.5 25 YEAR FREQUENCY, RATE OF DISCHARGE (Q) Coefficient (e) = Coefficient (b) = Coefficient (d) = 0 .754 89 8.5 50 YEAR FREQUENCY. RATE OF DISCHARGE (Q) Coefficient (e) = 0 .745 Coefficient (b) = 98 Coefficient (d) = 8 .5 100 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e) = Coefficient (b) = Coefficient (d) = 000 73"7 -3 26 2 Drainage Calculations.xi s 0.73 96 8 RESULT T q PRE) = 2.2 min. Rainfall Intensity (1 2) = Rainfall Intensity (1 5) = Rainfall Intensity (1 10) = Rainfall Intensity (1 25 ) = 9.861 in /hr .•.•. a ... : ... • .•. '.•2•.••.'5•.'• ...•.•.•. ~.•-···················.•. • I •< • : } : : • • •: •t: : • 2l\43ifaf.$.•••••t .·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.··:·:···=·····:·:··-:-:-:-:-:·:·:-:-:-:-:-:·: .·.·.·.·.·.·.·.·.·.·-:·:-:-:-:-:-:-:-:-:-:-:-:-···· Rainfall Intensity (1 50) = Rainfall Intensity (1 100) SECTION #3 (MINOR) -POST-DEVELOPMENT GENERAL INFORMATION Description : Drainage area of site after development Drainage Area (A1) = 0 .544 acres (impervious area) Drainage Area (A 2) = 0 .000 acres (landscaped area) TIME OF CONCENTRATION CTc) GIVEN Maximum Travel Distance (D 1 ) = Velocity of Runoff (V1) = Coefficient of Runoff (C 1) = Maximum Travel Distance (D 2) = Velocity of Runoff (V 2) = Coefficient of Runoff (C 2) = 100 ft ft 2.00 f sec 0.90 0 ft ft 2 .00 fsec 0.45 **NOTE : Minimum Tc allowed = 10 min . 2 YEAR FREQUENCY . RATE OF DISCHARGE (Q) Coefficient (e) = Coefficient (b) = Coefficient (d) = 0 .806 65 8 5 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e) = Coefficient (b) = Coefficient (d) = 0.785 76 8 .5 10 YEAR FREQUENCY. RATE OF DISCHARGE (Q) Coefficient (e) = Coefficient (b) = Coefficient (d) = 0 .763 80 8 .5 25 YEAR FREQUENCY. RATE OF DISCHARGE (Q) Coefficient (e) = Coefficient (b) = Coefficient (d) = 0 .754 89 8 .5 50 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e) = Coefficient (b) = Coefficient (d) = 0 .745 98 8 .5 100 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e) = Coefficient (b) = Coefficient (d) = 00 0 73 7-3262 Dra ina ge Calculati ons .x is 0 .73 96 8 RESULT T c1 = T c2 = T C(POST) = Rainfall Intensity (I~ = Q AREA 1 : Q AREA 2 = Rainfall Intensity (1 5) = Q AR EA 1: Q AR EA 2 = Rainfall Intensity (1 10) = Q AREA 1 : Q AREA2 = Rainfall Intensity (1 25 ) = Q AR EA 1 = Q AREA2 : Rainfall Intensity (1 50) = Q AR EA 1 = Q AR EA 2 : Rainfall Intens ity (1 100) Q AREA 1 = Q AR EA 2 : 0 .8 min. 0 .0 min . 0 .8 min . 6 .327 in/hr 3 .123 cfs 0 .000 cfs 7 .693 in/hr 3 .798 cfs 0 .000 cfs 8 .635 in/hr 4 .263 cfs 0 .000 cfs in/ 9 .861 hr 4 .868 cfs 0 .000 cfs 11 .148 in /hr 5 .503 cfs 0 .000 cfs 11 .639 in/hr 5 .746 cfs 0 .000 cfs SECTION #4 -HYDROGRAPHS Chart 4 2-YEAR HYDROGRAPH Volume Conveyed 3 ~ (J ~ -~ ~ ~ u -00 ..... ~ 2 0 10 8 Post-Dev elopment 8 Pre-D eve lopme nt ! HYDROGRAPHS Chart 4 1,405 ft 3 TllVIE (min) 20 30 SECTION #4 -HYDROGRAPHS Chart 5 5-YEAR HYDROGRAPH 3 li;;"l CJ p:: -~ ~ = i:.J u -rJ) .... ~ 2 0 10 m Post-Development El Pre-Deve lopment HYDROGRAPHS Chart 5 TIME (min) 20 30 SECTION #4 -HYDROGRAPHS Chart 6 10-YEAR HYDROGRAPH 3 ~ "" 0::: < -~ =:i:: ~ u -rJJ .... ~ 2 0 10 ml Po st-Development El Pre-D evelo pme nt HYDROGRAPHS Cha rt 6 TI1VIE (min) 20 30 SECTION #4 -HYDROGRAPHS Chart 7 25-YEAR HYDROGRAPH 0 10 8 Post-Development El Pre-D evelo pm e nt i HYDROGRAPHS Chart 7 TliWE (min) 20 30 SECTION #4 -HYDROGRAPHS Chart 8 50-YEAR HYDROGRAPH Volume Con veye d 2 ,477 ft3 4,.._ ________ _r, --~ 3 (.,l .. ~~~~~~~~--l - 1 0 0 10 (])Post-Deve lopment El Pr e-Deve lopment TIME (min) HYDROG RAP HS Chart 8 20 30 SECTION #4 -HYDROGRAPHS Chart 9 100-YEAR HYDROGRAPH Volume Con veyed 2 ,586 ft3 6 ~ (.!) ~ -~ ~ 5 = ~ u -1JJ. ..... Q 4 0 10 El Pre-Development El P ost-De velopme nt ! Tll\tlE (min) HYDRO GRAP HS Chart 9 20 30