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Home My WebLink About39 Development Permit 390 Winter Par Duplexes (Blocks S1 Lots 1,2,3)DRAINAGE REPORT FOR s LOTS 1, 2 & 3; BLOCK 51 UNIVERSITY PARK, SECTION II COLLEGE STATION, TEXAS PREPARED FOR: Alberstadt, Inc. 15907 River Road Houston, Texas 77079 PREPARED BY: Municipal Development Group P.O. Box 9249 College Station, Tx. 77842 Approved by North Bardell, P.E. ~ ,J~~ ~, tt~ , J-l~tf ~ fV' TABLE OF CONTENTS I. General Location II. Property Description ill. Drainage Basin Description IV . Drainage Facility Design V . Runoff Calculations A. Pre-Development B. Post Development VI. Conclusions LIST OF FIGURES 1. Figure 1: Runoff Hydrograph 2. Figure 2: Site Drainage Plan and Drainage Area Map \ GENERAL LOCATION The subject tract is positioned on the North side of Winter Park Road approximately one block West of Autumn Circle in University Park subdivision . The proposed development will be almost adjacent to the joint city limits line of College Station and Bryan. PROPERTY DESCRIPTION s· .-r Lots 1, 2 & 3; Block 51 of the University Park, Section Il subdivision comprise a total of 1.717 acres. The land is currently unimproved grass , weeds , brush and trees in a natural state . The tract is relatively flat and drains in a Northwesterly direction with an average grade of under 1%. primary channel , thus requiring no detention facility construction . (See page 10 and 13 of the City of College Station "Drainage Policy and Design Standards"). The tract does not lie within the floodway as depicted in FEMA-FIRM, No. 4804JCOJ42 : July 2, 1992 . \ ~~~ ~~.Or J~s~~ ~~---o ~ .(~) ~l;Jz, .. RUNOFF CALCULATIONS STORM WATER RUNOFF CALCULATIONS A. Pre-Development Description Grassland Roadway Area c (c)(Area) 1.44 0.35 // 0.504 0.277 0.9 0.2493 -----------1. 717 0.7533 Useful c = 0. 7533/1. 717 = .439 B. Post-Development Area 0.21796 c 0.9 1 (c)(Area) 0.196164 Description 4-4PLEXES access drive & parking landscaped area 0.523 0.9 ~ 0.4707 0. 969 0.35 0.33915 -,------------1. 711 1.006014 Useful c = 1.006/1. 717 = .586 **** Use Tc = 10 minutes **** C. Runoff Q=clA Qpre = I(.439)(1.717) = 0.7538(1) Qpost = I(.586)(1.717) = 1.006(1) I Storm Fre . Intensity Qpre I==================~ 5 7.7 5.804 10 8.6 6.483 25 9.9 7.463 50 11.1 8.367 :.::.·::.::.·:.-::.::.::.::.::.::.::.::.::.::.1. oo. ·.·. •.::.:·.>.:•.:•.:•.:•. :::::::::::::::::::•:1z~:•::::::::::::::::::::::::::9A9s :::::::::::: ~'-'-'-'-'-'-'-'--'-'"-'-'-'-'-'-'-'-'-~-'-'--'-'-'--'-'·~·. ~· .. "-'-. ·~· ·'-"-'-'.· ................... · .... . J Qpost 7.746 8.652 9.959 11.167 12676 Runoff Hydrograph 100 year Frequency Storm Figure 1 11,408 c.f.-~ -12.676 c.f.s. (Post Development) 12 ···························-······················ ............................. ·································································-·····················································-··············-········· 8,550 c.f.s. (Pre-Development) 10 ················································································ ...................... ························································································································ -8 ······-···················· .. ····---···-······ ·······-·-····· ................................... .............................. ··-··············································-·······························-············ 8550 c.f. 0 6 ............................................................................................................................................................................................................................. . 4 ............................................................................................................................................................................... -·····························-··············· 2858 c.f. increased runoff o --~~~~~~~~~~~~~~~~~~~ 0 10 20 30 Time (min) CONCLUSIONS From the previous page of calculated runoff quantities, it has been determined that a 2858 c.f. runoff rate will exist after development has occured on the subject tract. Approximately 27% of the land will be improved with buildings and streets . ,/ According to the College Station Drainage Policy and Design Standards, there are no detention facility requirements, therefore the flow will be allowed to maintain existing sheet flow conditions to Burton Creek Tributary A. DRAINAGE REPORT FOR ·' LOTS 1, 2 & 3; BLOCK 51 UNIVERSITY PARK, SECTION II COLLEGE STATION, TEXAS PREPARED FOR: Alberstadt, Inc. 15907 River Road Houston, Texas 77079 PREPARED BY: Municipal Development Group P.O. Box 9249 College Station, Tx. 77842 Approved by North Bardell, P.E. ~ r«--'~ '2/~113 ~ rw'Jv '/r-z.Jet4 ,J~ iAlf\1( ~~ ~ GENERAL LOCATION The subject tract is positioned on the North side of Winter Park Road approximately one block West of Autumn Circle in University Park subdivision . The proposed development will be almost adjacent to the joint city limits line of College Station and Bryan. PROPERTY DESCRIPTION Lots 1, 2 & 3; Block 51 of the University Park , Section II subdivision comprise a total of 1.717 acres . The land is currently unimproved grass , weeds , brush and trees in a natural state . The tract is relatively flat and drains in a Northwesterly direction with an average grade of under 1 %. One hundred percent of the tract sheet drains into immediate tributaries of Burton Creek. primary channel, thus requiring no detention facility construction . (See page 10 and 13 of the City of College Station "Drainage Policy and Design Standards"). The tract does not lie within the floodway as depicted in FEMA-FIRM, No . 48041COl42: July 2, 1992. t ~~~ ~~.Or J~5~~ rr~---o ~ .(~) ~lJJz,.. STORM WATER RUNOFF CALCULATIONS l. Pre-Development Description Grassland Roadway Area 1.44 0.277 1.717 c (c)(Area) 0.35 // 0.504 0.9 0.2493 0.7533 Useful c = 0.7533/1.717 = .439 J. Post-Development C. Runoff Description 4-4PLEXES access drive & parking landscaped area Area 0.21796 0.523 0.969 1.717 c 0.9/ 0.91 0.351 Useful c = 1.006/1.717 = .586 **** Use Tc = 10 minutes**** (c)(Area) 0.196164 0.4707 0.33915 1.006014 Q=cIA Qpre = I(.439)(1.717) = 0.7538(!) Qpost = 1(.586)(1.717) = 1.006(1) I j Storm Fre . Intensi Q re Q ost 5 7.7 5.804 7.746 10 8.6 6.483 8.652 25 9.9 7.463 9.959 50 11.1 8.367 11.167 ·:::··:::•:•••••••:•:•:•••••:1®::::.::::::::::•:•:•:•:.:•:•:•:•:::::::::::::1:z6.::::::·:::::::::::::::::::::9;;19s :•·•:::::::: 12616 Runoff Hydrograph 100 year Frequency Storm Figure 1 8 ······-·························································································· .............................. ································································································ 8550 c.f. 6 .................................. ·····························································································-······················ ····································································-·· 4 ....................... ···-· ···················································································································-··············· .............. -·························-·················· 12858 c.f. increased runoff I 2 --•• -mm mmmmmm •m• • • • ). ••• L m•••-•-•m •-•••••m•••••-•••™ m -m-m o ---~~~~~~---,-~~~~~~~-y-~~~~~~~ 0 10 20 30 Time (min)