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Home My WebLink About16 Development Permit 560 Kapchinski Hill SubdSTORMWATER DRAINAGE ANALYSIS KAPCHINSKI HILL SUBDIVISION TEXAS AVENUE AT HOLLEMAN DRIVE COLLEGE STATION, TEXAS Frn CULPEPPER REAL TY COMPANY COLLEGE STATION, TEXAS BY M.L. HAMMONS, P.E . COLLEGE STATION, TEXAS M. L. HAMMJNS, PE 1700 Ifyle South, suite 240 College station, Texas 77840 September 18, 1990 Mr. David Pullen, City EnJineer City of College station College station, Texas RE: College Station SUbdivision utilities Review Dear Mr. Pullen: In the process of plattirg the Kapchinski Hill SUbdivision, sto:nnwater drainage an::l sanitary sewer considerations were analysed an::l presented to the City of College station EnJineerirg Department for approval. To fully an::l properly develop the analysis in each of these two site developrent factors it was mandato:ry that the Polar-BEK real estate property ncM beirg :reviewed in the city plattirg approval process, be considered. 'Iherefore, a CO'fl'i of each of those two items is submitted herewith for feasibility review an::l for concept approval. Upon your concurrance the analysis an::l all required constnl.ction documents will be submitted for your approval prior to final plat approval an::l filirg. MIH/pc STORMWATER DRAINAGE ANALYSIS KAPCHINSKI HILL SUBDIVISION TEXAS AVENUE AT HOLLEMAN DRIVE COLLEGE STATION , TEXAS FUl CULPEPPER REAL TY COMPANY COLLEGE STATION, TEXAS BY M.L. HAMMONS, P.E. COLLEGE STATION , TEXAS TABIE OF a:Hl'ENTS 1. 0 IN:mOIXJCl'ICN 2.0 SITE 2.1 Site Topograiity 2.2 Drainage Basin 2.3 ~Site Drainage 3.0 PRORlSED mAINAGE PIAN 3.1 Run off calculation criteria 3.1.1 Q = ciA 3.1.2 c 3.1.3 i 3.1.4 A 3.2 Run off calculation 3.3 Run off Control 3.3.1 Detention Requ.i.renent 4. 0 S'lORMWATER DE'!'ENI'ICN 4.1 Detention storage Inflow 4.2 Detention storage Di.schazge Illustration 1.1 Illustration 1.2 Illustration 2 .1 Illustration 2.2 Illustration 2.3 Site Ia:ation Map Proposed Plat Site SUl:vey (Hoose, etc.) Site SUl:vey (Tope) City of College station Drainage Basin Map Figure 3.1 Figure 4.1 Figure 4.2 Tri.argular Hydrograiil crart Drainage structure Drawirg Detention storage Inpit Schematic APPENDIX A R ,ROPDSAL •II I I I SUBDIVISICN IEAINAGE 1.0 IN!roIXJCl'ICN Oll.~ Management, In::. is proposin;J the developnent of eighteen+ (18.2) acres of lam in the Sa.rt:hwest quadrant of the Texas Avenue am Holleman Drive intersection in CollE!.CJe station, Texas (see Illustration 1.1). As shown by Illustration 1.2 the site is to be platted as two (2) lots. An additional, adjoinin;J fcmteen (14) acres owned by the Polar-Bek cmpany is also planned for developnent at a later date. By agreement between the two property owners the drainage is to be evaluated am jointly controlled to meet city drainage criteria. 'Ihe eighteen+ (18.2) acres is planned for retail sales useage am the fcmteen (14) acres is planned far lmllti-family usage. 2.0 SITE 'Ihe drainage site (oanbined 18+ am 14+ acres) is presently mrleveloped except far four ( 4) larrlowner banes am several attemant out buildin3s (see illustration 2.1). 'Ihe site is VecJetated by grasslam am a few trees located aramd the hooses. Sane areas are covered with a sanewhat dense starrl of brush am blshes. 2.1 SITE '10~ As shown by Illustration 2.2 the site is situated an a gentle downward slope predcminantly fran North to sooth. '1here are no natural or man made streams passin;J through the site or eminatin;J fran the site. 2.2 mAilW2 BA.SIN As shown by Illustration 2.3, the drainage site is in the carter Creek drainage basin, within the Bee Creek run-off area, on Bee Creek, upstream fran the canfluenoe of Bee Creek am Bee Creek Trib.:rt:ary "B". 'Iherefore, as described by the City of CollE!.CJe station Drainage Policy am Design starrlards (hereinafter "DP & ts"), section II.D., Page 10, excess sto:rmwater detention is required to the twenty five (25) year storm Frequency. F.I.R.M. flood maps far the area .in:licates no one hundred (100) year flood plane within or eminently near the site. 2.3 EXISTING SITE IEAINAGE '!he existirg natural terrain dictates a predaninantly Southerly flow of surface run-off. None of the site nm-off drains to Hollemen street am none of the Holleman street drainage runs onto this site. Similarly, none of the Texas street nm-off drains art:o this site, but a small area in the far Saitheast oomer of the property drains to an existin:J surface drain ditch alorg the Fast side of Texas Averrue. Drainage fran the site appears to alJlcst exclusively drain fran the immediate area via a natural drainage tr.ibrt:acy originatin;J at the Sart:hwest corner of the drainage site an:i exten:IinJ approximately six hun:ll"ed (600) feet to an Andersal Stteet culvert structure, therxJe approximately fifteen hun:ll"ed (l,500) feet to Bee Creek. 'llle lan:i area West of this drainage site, bit F.ast of Andersal street an:i Sa.Ith of Holleman street also drain through the same Amerson street culvert structure. 'llle lan:i area Sa.rt:h of this site, bit North of Brentwood between Texas Avenue ani Andersal street drains further Sa.rt:h, 1'X1t through the Andersal street culvert structure. 'lherefore, approximately 52 acres drain through the Andersal Stteet culverts. 3.0 PROFOSED mAnW;E PIAN In order to achieve sto:cn:&rclter control ac::cordirq to ordinance #1728, Olapter 13 of the Ccrle of Ordinances of the City of College station, the follov.rin;J controls are proposed. 1. '!hat the eighteen + (18. 2) acres which is the subject of this prcposa1 be oanbined with the fourteen (14) acres owned by the Polar-Bek C)'Jnpany, for consideration as the drainage site. 2. '!hat the pc:ist-devel.qment nm-off rate 1'X1t exceed the pre-develqment nm-off rate. 3. '!hat the nm-off control be designed for the twenty five (25) year (4% probability) stom frequency. 4. '!hat floodwater be managed up to the one hun:ll"ed (100) year (1% probability) stonn frequency. 5. '!hat the Andersal street culvert capacity be evaluated an:i considered in the flow capacity analysis. 3.1 Rm-OFF CAI.CmATICN CRI".IllUA sto:cn:&rclter nm-off is calculated ac::cordirq to methods acceptable in the City of College station DP & ns manual. 3.1.1 Peak Discharges (Pre & Post) are calculated by the Rational Formula (Q-= ciA) since A) 'llle nm-off area is less than fifty (50) acres. B) 'llle discharge is 1'X1t of the ''primacy system'' • C) 'llle flow beirg calculated is as described by the Drainage Design starxiard, Section III, Paragraph B.2.d., Page 17. 3.1.2 RLm-off coefficient (c) is established at .35 for pre-developement am .75 for post-developoent calculation as presented by Table III-1 of the previously refererad DP & oo marrual for 1% slope natural grasslam am 1% slope high density residential am blSiness/cxmnercial. 3.1.3 Rainfall intensity (i) is established as shown bel.C7.tl, fran the DP & 00 marrual Figure III-1. Post develOfllSllt Pre DevelOfllSllt 3.1.4 'lhe site area is 18.2 acres + 14 acres + a o.s acre perimeter, less a small section of approximately 2.s acres at the sart:heast comer, definin] a net area of cx:msideratian; A = 30.2 acres. 3.2 HJN-OFF CAU:m.ATION In cx:msideratian of the factors defined in Paragrapi 3. l above an:1 by use of the Rational formJ.l.a, site nm-off is calculated to be: Post Developnent Pre Developnent 1--~~~~~~~~~~---11--~~~ Q 25 -215.2 cFs Q • 274.0 CFS Q 25 = 88.8 CFS Q • 115.2 CFS '!be point of calculated discharge is at the soothwest oorner of the combined plat pz:qa;al area am Polar-Bek tract (as identified an Illustration 2. 2) • 3.3 HJN-OFF cx:NmOL In order to adl.ieve any desired degree of nm-off control, stormwater storage space am a regulated flC7.tl release structure must be provided. By lllltual agreement the property owners of the two lam areas cx:msidered herein prc:pose to provide a plblic easenent area of forty (40) feet by five hmm'ed twenty one (521) feet alCDJ the So.Ith property line of the Polar-Bek catpany tract. '1his proposed e.asenent lies adjacent to an existin;J ten (10) feet plblic easement, which lies within the Parkway Plaza subdivision. '!be combined easements would then heo"rne a pmlic easement fifty (SO) feet wide by five hmm'ed twenty one (521) feet lCDJ, provi.din; a site nm-off detention area adequate for the required detention volume. 3.3.1 Detention requirements As provided by the DP & IS manual, detentiai volmne is detennined herein by cxrrparisan of the supe.rirrpisecl hydrograPls of the pre an:l post developnent nm-off. Figure 3.1 shcMs a tr~ar ~raximation hydrograpl for both Pre an:l Post Q25 RLm-off calculations. On the same figure, the "design" hydrograiil is also shc:Mn. 'lhe required detention volume is imicated thereon as that graiil area exceedirX] the "design" I Q25 nm-off rate, rut within the Post developnent, Q25 RLm-off. calculation is by cxmversion of the Figure 3 .1 graiil area to the units represented. 'lhe area of consideration is fran nm-off onset until the i.?xlanin; Post-Developtent flow rate, durin;J decline, is equal the predetemined allowable discharge rate. In this case such flow rate will occur at 23.92 min. fran onset. AccordinJly the required storage volmne is 93,153 C.F. as calculated tlms. Irxx:mirg Volume to be Cklnsidered 188,859 CF 33 x 60 x 215.2 x 0.5 = 213,048 -( 9.08 x 60 x 88.8 x 0.5) - ( 24.189) 188,859 CF Discharged Volume Dlrin;J Same Time (95,706)CF 2.81 x 60 x 55 x 0.5 = +21.11 x 60 x 55 x 1.0 = +21.11 x 60 x (88.8-55) x 0.5 ... 4,647 69,663 21.406 [ 95,706] I Net storage Volmne Required ____ 9_3_,_15_3_CF __ _ (calculations based on onset of flow restriction at awraxbnately 55 CFS). See Figure 3.1. 4. 0 S'1m!WATER DETENI'ICti With a known det.entia'l volmne requirement an:l a known area of placenent, the detention storage structure is designed as shown by Figure 4.1. 4.1 Detentiai storage Inflow Based ai the Rational method of calculation used ~ this analysis, a Q25 peak discharge flow rate has been calculated for each of the two prq>erties considered herein. Accordin;Jly Figure 4. 2 inlicates those flOltl rates as separate inp.its into the detention storage area. Based an these rates an:i an the natural terrain encoontered at the storage area, two separate (separated by partition only) storage cxmpartments have been designed. Fach ccanpartmant is proportional in size to the incc:.min:1 flOltl an:i each carpartment is designed with elevations carpatible with the anticipated desirable finish grade elevations. '!he :results of these considerations are irxx>zporated into the detention structure design as shown by Figure 4.1. 4.2 Detention storage Discharge Discharge fran this site has been concentrated at the origin point of the natural drainage creek at the Southwest corner of the detention site. Figure 4.1 shows the structures involved an:i the outfall gec:metty. With energy dissapators an:i rip rap apron, the outfall flOltl rate will be reduced to levels that will prevent significant erosion arx:1,lor property damage. '!he final discharge orifice is sized acoordi.rg to the Q = 19.636 Kd formula, with construction of an equivalent ~ar openin;J. Design discharge flOltl is of orurse, 88.8 CFS with detention storage at 301.0' elevation, which is full storage level. An additional l. o foot of detention elevation is provided to control stormrlater levels up to the one hurxh'ed ( 100) year stonn frequency requirement. A discharge orifice is bJ.ilt into the detention pan1. partition wall to balan=e flOltl for s.i.m..11.tanea.ls fillin3' of both cx:mpartments at the twenty five year level. ILLUSTRATIONS• II I I I IC u g IC l(IUtELEY I WESTOVER' r-i r-i z 0 H 8 ~ 8 Ul ::> H H H 11111•sat:1nEJ1::1 : --:-_ ~:: -~--· 1-· :T -~-L= ~-:£==~ ;_:::r:~: '=~t< ~~-;:: ~~;:;. t~f(:: =~ :~ ~h~ -:~I~J :~+-:= :~~-~ --~ --'1---if.---l~~~:=-:1 f§= ~~_a·t _:-~-~=== ~s ~:·-~:i: :~~~ ~~!~ ~=:~:-~~ ~:::_~17-t"° --~ : ......... ~-.,....._ ::!-:.:. ~ .. :1=---:1:t _ ·---~• ---...---,...,,_ ---·-·-r _ :..:.:_c::::::....l.•·-:::: ---i--...---....c.:::::-c.:-· ·-~~-----·· -:::-.;-:: ·rr_ ----+-::-_-:i -: ~~---~ ---=-= -~·:::. .:::~r : ::~:t:::: ~; ::-__ h::--!:. ~== ~-:::: --=~ -1==- _::-1: :. ·::.:,:::. §:-;;;:: -~~~ ;~ ~~ :~·i:~,~~= i".-:f:i -~::!:< DRAINAGE STRUCTURE DRAWINGS : Drainage structure drawings are furnished by separate 2' X 3' blueprints and are an integra l part of this analysis. FIGURE 4.1 --.-----------------...-------------------------------------------------------..... ----~ NJ.<-! U 12.A L~ --~ W -A 11,1 A;-(,12· w .r:.:.\::. ~~- &DH ~o-..>U -E-'/' Q Z.F, OL-X\" L-i;:: .• \ ....... ----MANI-"~ i::.1./' iO· -:., / r/l<":.;,_:.,.µ1-\~.'..tAE-f,J~ '(_, '((?_. / v N <E-A Cl) A..7 .h ce, OE.-n:;..N-T\OIJ N~A (0 V DL.., ~% O~ (O\AL- /-"·J<.CA. (f) 4-\. z. c r=s A -1 v:1 r'-l ·11<:.c' 1-L-F -D IN vu.-r °14 . v ~ (OEVE.L(.;l"E v) r:=-~ !"--'\ l 4-A 6 IZ--t;::h F tJTU.1 <'...E, MLlL:-r\ · f'.'.'AMl \-'-\' /.,JZ.\'5:f>, 'YtO~&iE. r-P l?&l-tA-1<61\:'.:. A(!.(? c.r-~, L' p.. "\ (.0 1'-~ ·"\\2 (;;: L-l-1-::-C.~ :>.X'fl--~.:\ ...... ----==~ ~ISt-.\T l cN l";"'-i<A (fJ VOL-. :SA 7o CF' \0\ ;-\ L- f::> t O f<:.A &1 E:.- A '--....l Fl2-o M it.·,. ?.. A C..-tz.f;.<; p R O eL.> ~ E::-f') F'1.--r .... --r-r I N &1 A rz I:.. A I F IGURE 4 . 2 I N oi":'--TH APPENDIX A•ll l ·I I STATE OF TEXAS COUNTY OF BRAZOS s s s KNOW AIJL MEN BY THESE PRESENTS: EASEMENT That POLAR-BEK COMP ANY , an Alabama General Partnership, for and in consideration of the sum of TEN AND N0/100 ($10.00) DOLLARS, and other good and valuable consideration to it in h a nd paid by CULPEPPER PROPERTIES, INC., the receipt o! which is hereby acknowledged, has GRANTED AND CONVEYED, and by these presents does GRANT AND CONVEY unto the said CULPEPPER PROPERTIES, INC. , its aucc esso rs and assigns, a non-exclusiv~, perpetual easemont and right-of-way upon and across the following described tract for the ~ole purposes as Qet out below: Being all that certain tract or parcel of land lying and being situated in Br<J.zos County, Texas, out o! the Crawford Burnett Leagua, A-7 in the City of college station, and being a part of a 20 .00 acre tract conveyed from R. George Molina Trustee, to College Park As&ociates by Deed recorded in Volume 508, Page 765, of the Deed Records o! Brazos county, Texa5, and being more particularly deacrib~d as !ollows: BEGINNING at a 1/2 11 iron rod at the south corner of s<:i.id 20.00 acre tract on the Northwest lino of Parkway Plaza, Phase 8 for the South corner of this easement; THENCE N 36-03-16 w, a distance of 40.17 feet along the Southwest lina of this easement also being the Southwest line of said 20.00 acr0 tract to a point for the West corner of this easement; THENCE N 48-44-33 E, a distance o! 521.00 feet along the Northwest line of this eas~ment, being parallel and perpendicular to the Southwe5t line of said 20.00 acre tract, to a point for the North corner of this easement; THENCE S 36-03-16 E, a distance o! 40.17 feet along the northeast line o! this ea,ement to a point on the Southeast line of said 20.00 acre tract and the Northwest line of said Parkway Plazu for the East corner of this easeme nt; THENCE s 48-44-33 w, a distance of 521.00 feet along the Southeast line cf thiQ ea sem ent also being the Southeast line of said 20.00 acre tract and the Northwest line of said Parkway Plaza to the POINT OF BEGINNING and containing 0.4784 acres of land as survoyed en the ground under the direct and personal supervision of Ounte Carlomagno, R.P.S. 11562. The Or~ntee is hereby granted Gaid easement and right-of-way for the sole purpose of placing, construct ing, operating, maintaining , rebuilding, replacing, relocating and removing a storm sewer (surface water drainage) pipeline and surface water detention pond, and Granter herein hQreby roogrVQS and retain& the right to convey 111imilar rightsi and oasements to such other parties aE; Grantor ma y deem appropriate, provided such rights and easemen ts do not ma terially interfere with Grantees utilization of Grantee's eaaeroQn t and rights . Grantee covenants for i ta elf, and for i ta successors and ass igns , that i mm ediately aub sequent to any construction, repair, removal or ma intonancQ performed by Grantee or its succes sors or assign s , upon said pipeline or retention pond, that Grantee shall replace and restore all landsca ping, paving, curbing, or other improvements, which have been da maged, relocated or removed during the construction, repair, removal or maintenance, and shall pay Grantor r~asonabl~ compen~ation for $UCh landscaping, curbing, and paving which may not bQ replaceable or restorable to its former condition. Grante• agrees on behalf of itself and its ouccessors and aesi gns, to design and improv o the easement property herein desc ribed , to acco:mroodate in accordance with requirements set forth by t he City of College Station, Toxas, the surface water drainage from both the property conveyed to Grantee by Grantor simultaneous herewith (consisting of 5.9759 acres), and the remainder o! the 20.00 acre tract referred to in the description of this easement, and upon which this easQment is located, provided the said balance of said 20. oo acre tract is dGVeloped and i mproved pursuant to docume ntation heretofore submitted by Grantor to Grantee. In tha event Grante~, or its successors or assigns, fail to p erform any covenant, understanding, or obligation arising from this eas~ment i nstrument, after written demand, all r ights and privileges granted hereby shall terminate, and be of no further !orce nor effect . Grante e agrees and covena nts to join in any dedicati on of said easement t o any public entity for use as a public storm sewe r (surface water drainage) pipeline and retention pond, provided Gran t~o 's utilization o! said easement es aforesaid is not substantially and materially d0trimentally ·affected or disturbed. The parties hereto he reby agree that in the event of a controv~rsy, claim or disputQ relating to a brQaoh of any portion of this o asement agreament , the prevailing party sha l l be e n titled to recovor reasonabl e o xpenses, attorneys fees, and costs from the l o l3 ing party, This a grcQ~ont is binding on the parties herot o, the i r s uccessors and assigns , and is both per!ormabl o and e nf o rc e a ble in Br azos County, Texas . WITNESS my hand th is 2nd day o f April , 1990 . ST ATE OF ALABAMA S s CO UNTY OF J EFFERSO~ S POLAR-BEK COMPANY By : _______________ _ Name : ____ ~~~~----~~~- CULPEPPER MANAGEMENT , I NC. By : ____ ~--------- Name : __ ~~--~~~--~~--- Th i s in s trument was acknowledged beror e me on this the __ day of April 1990, by , ~n behalf of Polar- Bek Co mp a n y, an Alabama Gen e)ral Pa r tn_ersh ip. NOTARY PUBL IC STATE OF ALAB AMA Hy Cor...r:iission Expir e8:--'---~~- S TATE OF TEXAS S § COilliTY OF BRAZOS S This inatrui::ent was acknowledged before ne o n this the __ da y of Apr il 1990 , by ------------' , of Culpepper Management , Inc., a Texas corporation, on beha lf o f s a id c orporation. NOTARY PUBLIC STATE OF AL1'.B~J1A l~y Co::-.!:!ission Expires : _____ _