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Home My WebLink About58 Castlegate Sec 5 Ph 2 04-29DEVELOPMENT PERMIT PERMIT NO. 04-29 Cf W Project: CASTLE GA TE SECTION 5, PHASE 2 COlllGl STATION FOR AREAS INSIDE THE SPECIAL FLOOD HAZARD AREA RE: CHAPTER 13 OF THE COLLEGE STATION CITY CODE SITE LEGAL DESCRIPTION: Castlegate, Section 5 Phase 2 All Lots DATE OF ISSUE: 09/01/04 OWNER: Greens Prairie Investors, Ltd. 4490 Castlegate Drive College Station, Texas 77845 TYPE OF DEVELOPMENT: SPECIAL CONDITIONS: SITE ADDRESS: 2270 Greens Prairie Road DRAINAGE BASIN: Spring Creek VALID FOR 12 MONTHS CONTRACTOR: Full Development Permit TEXCON General Contractors 1707 Graham Road College Station, Texas 77845 All construction must be in compliance with the approved construction plans All trees required to be protected as part of the landscape plan must be completely barricaded in accordance with Section 7.5.E., Landscape/Streetscape Plan Requirements of the City's Unified Development Ordinance, prior to any operations of this permit. The cleaning of equipment or materials within the drip line of any tree or group of trees that are protected and required to remain is strictly prohibited . The disposal of any waste material such as , but not limited to, paint, oil , solvents, asphalt, concrete, mortar, or other harmful liquids or materials within the drip line of any tree required to remain is also prohibited . TCEQ PHASE II RULES IN EFFECT . 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. If it is determined the prescribed erosion control measures are ineffective to retain all sediment onsite , it is the contractors responsibility to implement measures that will meet City, State and Federal requirements . 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. 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 inside 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 above named project and all of the codes and ordinances of the City of College Station that apply. 01-01-o f Date DEVELOPMENT PERMIT PERMIT NO . 04-29 ~-v Project: CASTLEGATE SECTION 5, PHASE 2 COlllGl STATION FOR AREAS INSIDE THE SPECIAL FLOOD HAZARD AREA RE : CHAPTER 13 OF THE COLLEGE STATION CITY CODE SITE LEGAL DESCRIPTION: Castlegate , Section 5 Phase 2 All Lots DATE OF ISSUE: 09/01/05 OWNER: Greens Prairie Investors, Ltd. 4490 Castlegate Drive College Station, Texas 77845 TYPE OF DEVELOPMENT: SPECIAL CONDITIONS: SITE ADDRESS: 2270 Greens Prairie Road DRAINAGE BASIN: Spring Creek VALID FOR 12 MONTHS CONTRACTOR: Full Development Permit TEXCON General Contractors 1707 Graham Road College Station, Texas 77845 All construction must be in compliance with the approved construction plans All trees requ ired to be protected as part of the landscape plan must be completely barricaded in accordance with Section 7.5.E., Landscape/Streetscape Plan Requirements of the City's Unified Development Ordinance, prior to any operations of this permit. The cleaning of equipment or materials within the drip line of any tree or group of trees that are protected and required to remain is strictly prohibited . The disposal of any waste material such as , but not limited to, paint , oil , solvents , asphalt, concrete , mortar, or other harmful liquids or materials within the drip line of any tree required to remain is also prohibited . TCEQ PHASE II RULES IN EFFECT. 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 . If it is determined the prescribed erosion control measures are ineffective to retain all sediment onsite , it is the contractors responsibility to implement measures that will meet City, State and Federal requirements . 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 . 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 facil iti es . I hereby grant this permit for development of an area inside 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 appl ication for the above named project and all of the codes and ordinances of the City of College Station that apply. fY]-01-os- Date C{-~-0..5 Owner/ Agent/Contractor Date FOR OFFD?t=E ONLY P&Z CASE NO.: , \4 l "' DATE SUBMITTED : OlD -b1 fil FINAL PLAT APPLICATION A · (Check one) 0 Minor ($300 .00) D Amending ($300 .00) [J1' Final ($400 .00) D Vacating ($400 .00) D Replat ($600.00)* *In c lud es p ubl ic hearing fee The following items must be submitted by an established filing deadline date for P&Z Commission consideration . MINIMUM SUBMITTAL REQUIREMENTS: /Filing Fee (see above) NOTE : Multiple Sheets -$55 .00 per add it ional sheet !!../Ii_ Variance Request to Subdivision Regulations -$100 (if applicable ) v Development Permit Appl ication Fee of $200 .00 (if app li cable). \/' Infrastructure Inspection Fee of $600 .00 (appl icable if an y public infrastruct ure is be ing constructed) / Appl ica tion completed in full. tJffe Copy of origina l deed restrictions/covenants for replats (i f a pplicab le). / Thirteen (13) fo lded copies of plat. (A signed mylar orig in al mus t be subm itted afte r staff rev ie w .)· ~One (1) copy of the approved Preliminary Plat and/or one (1) Master Plan (if appl icable). ~ Paid tax certificates from City of College Station , Brazos County and College Station l.S .D . V" A copy of the attached checklist with all items checked off or a brief explanation as to why they are no t. V' Two (2) copies of public infrastructure plans associated with this plat (if applicable) . .J:!./k Parkland Ded ication requ irement approved by the Parks & Recrea t ion Board , please provide proof of approval (if app li cable). Date of Preapplication Conference :_:::..::;_...:.:...~1--!-.J.:....!...~...:..:::=.,...:=.---i....~u.i...::1.!.!..!!l...--L!:..L-~~LJ.----- NAME O F SU BDIVISION ---1~""-"-'-'-"""~~~~~'"'1.J'-L.l...a!...~+--c~"-":::JLL.l.!~-'=<'!_~~~!!C;.-=-=---- SPECIFl ED LOCATION OF PROPOSED SUBDIVISION (Lot & Block)-=~...__,..,_,_____..:::::::.:_:_-"-"-_i.a:..Ll...L..=:~U=L--- fra_i rLec~ APPLICAN T/PROJECT MANAGER'S INFORMATION (Primary C o nta ct for t he Project ): Name Gzr-eens Pra/r,-e ,, :r:v, veshr5 . Ltd . -l<lt.LllC(.,c_f Plu t"l«IJ 5 Street Address 4..Lf10 (tt':i!RD1')q;t:;_, Driv-G 7 City f'ntf eqe. '5-CC1..}t{!V] State TX Z rp Code 1-rmr;; E-Mail Address - Phone Number {<iYI) l,'10 -72-50 Fax Number (J_1_C/~)-'-'_1l_0 ___ /0_4_1 ____ _ PRO P ERTY OW N ER 'S INFO R MATION : Name 6 c.ee--ns Pratrr-C In vesfvv-c; Ltd. Street Address iJlf10 &~ "Yd v-C c;ty Ca f/e-'je . ?fk//U>J State fX Zrp Code ~ E-Mail Address ·- Phone Number (171) Clf D -7Z.,C) 0 Fa x Number (1_7_9--,)r-fo-~-V---!M_I ____ _ ARC H ITE CT OR ENGINEER'S INF ORMATIO N Name ,Joe ScJ,u llz1 T> ,£ .. -Texan Street Address / 707 Gra__b:J tr) KDM City ~~1 . ~'?;;/J_ ~ State TX . z ;p Code ]791/5' E-M a;1 Address 1oe:Z L'iJ~=~Ca,., .... e_f-- Ph one Number {;111) l b f -71 't-3 Fax Number _@~_,__7-et~7J ',__A<..LL_,_ __ ~___.__,_~~-~------- G/13/03 " TEXCON GENERAL CONTRACTORS 10-Au g-04 ENGINEER'S COST ESTIMATE CASTLEGATE SUBDIVISION COLLEGE STATION, TEXAS SECTION 5, PHASE 2 -45 LOTS Item Estimated Unit Estimated No. Description Quantity Price Cost Sitework 1 Mobilization/Layout 1.0 LS $7,500 .00 $7 ,500 2 Site Preparation 2.0 AC $3,500.00 $7 ,000 3 Sediment & Erosion Control 1.0 LS $3,500.00 $3,500 4 Topsoil Stripping & Replacement 600 CY $4.50 $2 ,700 5 Excavation 2,600 CY $3.50 $9, 100 6 Lime Stabilized Subgrade 6,194 SY $3 .25 $20 ,131 7 Concrete Curb & Gutter 3,558 LF $8.00 $28,464 8 Base Material -6" depth 4,852 SY $6 .00 $29,112 9 Asphalt Paving -1 1/2" depth 4,852 SY $5 .00 $24,260 10 Concrete Apron 1,633 SF $5.50 $8,982 11 Seeding & Hydromulch 4,000 SY $0.50 $2,000 Subtotal $142,748 Storm Drainage 12 Drainage Pipe -24" RCP -structural 79 LF $44.00 $3,476 13 Drainage Pipe -27" RCP -non-structural 146 LF $40 .00 $5,840 14 Concrete S .E.T . -27" RCP EA $2,500 .00 $2,500 15 Junction box 1 EA $2,400 .00 $2,400 16 Inlet -15' wide 2 EA $3,600 .00 $7,200 17 Rock riprap 5 TON $75 .00 $375 18 Concrete Drainage Flume 75 LF $26.00 $1,950 19 Concrete Drainage Channel 170 LF $36 .00 $6,120 Subtotal $29,861 Water Lines 20 3" Water PVC CL200 (C909) non-struct 368 LF $17.00 $6,256 21 3" Water PVC CL200 (C909) structural 26 LF $21 .00 $546 22 8" Water PVC CL200 (C909) non-struct 1,105 LF $24 .00 $26,520 23 8" Water PVC CL200 (C909) structural 190 LF $30 .00 $5,700 24 Gate Valves -3" EA $400 .00 $400 25 Gate Valves -8" 4 EA $600 .00 $2,400 26 M .J . Tees -8" 1 EA $400 .00 $400 27 M .J . Tees -8" x 3" 1 EA $250 .00 $250 28 M .J . Tees -8" x 6" 2 EA $300 .00 $600 29 M .J. Bend -8" 11 .25 deg . 1 EA $300.00 $300 30 M .J. Bend -8" 22 .5 deg . 4 EA $450 .00 $1,800 31 M .J . Bend -8" 45 deg. EA $500 .00 $500 32 1" SS Water Service 4 EA $600 .00 $2,400 33 1" LS Water Service 5 EA $700.00 $3,500 34 1 1/2" SS Water Service 6 EA $650 .00 $3 ,900 35 1 1/2" LS Water Service 11 EA $750.00 $8,250 36 1" Blow Off Assembly EA $350 .00 $350 37 2" Blow off Assembly 1 EA $450 .00 $450 38 Fire Hydrant Assembly 2 EA $2,400.00 $4 ,800 39 Verti c al Ex tension for Fire Hydra nt 2 EA $250 .00 $50 0 40 Conn ec t to existing line 2 EA $35 0.00 $700 Subtotal $70 ,522 f ':J IJ(? I l)f 2 < I "" Sanitary Sewer Lines 41 6" SOR 26 Pipe -struct ; avg depth <8' 93 LF $26.00 $2,41 8 42 6" SOR 26 Pipe -non -str; avg depth <8' 221 LF $18 .00 $3,97 8 4 3 6" SOR 26 Pipe -str uct ; avg depth 8'-1 O' 257 LF $28 .00 $7 , 196 44 6" SOR 26 Pipe -non-str; avg depth 8'-10 ' 125 LF $20 .00 $2 ,50 0 45 6" SOR 26 Pipe -struct ; avg depth 10'-12' 72 LF $30 .00 $2, 160 46 8" SOR 26 Pipe -non -st r ; avg de pth <8' 48 LF $20 .00 $960 47 8" SOR 26 Pipe -non -str ; avg depth 8 '-10' 172 LF $24.00 $4 ,128 48 8" SOR 26 Pipe -struct ; avg depth 10'-1 2' 159 LF $36 .00 $5 ,724 49 8" SOR 26 Pipe -non -str ; avg depth 10'-12' 253 LF $28 .00 $7,084 50 8" SOR 26 Pipe -struct; avg depth 12'-14' 58 LF $40 .00 $2 ,320 51 8" SOR 26 Pipe -non-str; avg depth 12'-14' 172 LF $30 .00 $5,160 52 8" SOR 26 Pipe -struct; avg depth 14 '-16' 195 LF $44 .00 $8 ,580 53 6" ASTM-02241-struct ; avg depth 8'-1 O' 20 LF $28 .00 $560 54 8" ASTM-0 2241-struct ; avg depth 14'-16' 20 LF $46 .00 $920 55 Sewer Se rv ices 23 EA $700 .00 $16,100 56 M anholes - average depth <8' 3 EA $2,000 .00 $6,000 57 Manholes -av erage de pth 8'-1 O' EA $2,200 .00 $2 ,200 58 Manholes - av erage depth 10'-12' 2 EA $2,400 .00 $4 ,800 59 Manholes - average depth 12 '-14 ' EA $2 ,600 .00 $2 ,600 60 C onnect to existing line EA $500 .00 $500 Subtotal $85,888 Total S itework $142 ,748 Tot al Storm Dra i n ag e $29 ,8 61 Total Water $70 ,522 T otal Sanitary Sewer ~85,888 TOTAL CONSTRUCTION ! $329 ,0 191 A. 10:24a TEXCON ENGINEERING Notice of Intent (NOi) for Storm Water Discharges Associated with Construction Activity under the TPOES Construction General Permit (TXR15000,0) F0< help completif>9 thi$ .,pPtlcalion. read tt>e TXR 150000 NOi ll\Sltuc:tions (TCE0 -20022-lnslrucli~). 9?9?64??59 p.2 TCEQ Office Use Onl)I' TPDES Permil Number: TXR 15•.:_·:_·:_::_"· NO GIN Number:·: ..... ::_::_·:_·:_::....·:_ .. Customer Reference Number: CN GIJtl;'f(.t£41 E-mail Address: _________________ __,,------------------------ Type of Opera1oc 0 tndividucil 0 Sole Proprietorship -O.BA,6.Partneiship D Corporation 0 Federal Government 0 State Gover nment 0 County Government 0 City Government 0 Otner: _____ =---..,..---------- tndepeodent Operator? '6i Yes 0No Number of Employees :~ 0-20 0 21 -1DO 0 101 :250 0 251 ·500 0 501 or higher Federal Tax 10: 14-t.ft{,fl 310 State Franchise Tax ID Number. ·IJ/P-. DUNS Number: N(A 8 . Bifli"g Address. • Name: W.tl.ifu& titil~-~d't .Lwe.s..ftc,1 UJ. c . Mailing Addres5Ji41o74 sfu1~b::@r L City: CQl(~St-a:b' cm Stsle:..:z2!,Zip Code: l 19frS'° Coun'll)' Mailing lnformatiol\ (if outside USA) TerrilOry: -Counl.ry ~e : -Postal COOe : - Degrees("), Minutes fl. and Sec.onds (") 04lcimal Form Also. describe !he c011slruc1ion activity al. I his site (do no/ repeat the SIC code): . Has a storm water pollution prevention p!ao been prepa<eef as speciried in the general l)(!ttnit (TXR1 50000}? (g Yes O No Estimated area cl land disturbed (~o the nearest acre): /!;" Is lhe p<oject I site located on Indian Country Lands? 0 Yes IXl No Docs this projed I sile discharge stonn water into a municipal separ<Jte ste>rm sewer 6~m (MS4)? D Yes S No II yes. provide the name of tho MS4 Oi)eralor. _____________________ -=--:--......,.:----r---- Provide the name or segment numbor d lhe water bod)' that receives storm water rrorn Ch l'5 project I si1e: D . Cont;ic:t -If the TCEQ needs additional lnfoonalioo regarding lhis appr.catla11. who should be ocntaded 7 Name: WoJ~!~ T i tle:_.....W\,...,,,a;.....,.\1\4 ...... <1.qs;;~""-X"---.---..--.------ Phone Number: J§145Z2'100..}ii;§) Extension: FaM N~~r : ('tlet)GflO-lo4-I E-mail Addre:ss : E. Payment Information -Money Order Number. 4'7f3 Name on Check I Money Order. F. Certification I oertilr under ~•v otlawlhal tflis d-Ocumen1 was prepated under my~lion or supen.i,.;oA in accordance with a syslem designed to assure Cflill qual ifoed perso""et pioperty galhe< and evaluate the inrormatioo nbmil1ecl. Bosed oo mv inquiry ()f lhe person°' persons whomana"e ll>e syslem. orlflos4 persons direcUv responsble lo< 9alhering !tie informatloo, Ille information submitted ls, lo Ille best ol my knowledge Bild berief. IMI. accUl31e, and complele. I am aware there are s~nl penal4ies tor $Ubmilting false inlomlallon. including Iha posgitiility ol fine end lmprisonme11l for knowing viofalions. Construction Sile Oper.1tor: Prefix: O'\c. Last ~\U'2S I( you have que~l i ons on how lo r~I otJI this'°"" cx about the sCorm waler l)rOgram . lca5e c;onla~ u~ al (512}239-"671 . I l>dividuals are enlided to request and <eview ltw!it personal inlormalion lhal the agency 03thers on its forms . They lr\3y also h:lve any crrors: in their tnrormslion corre•-'80 . To review s;vctl inlormalion. contac:! us at (5121239-3282 . The QOmplettld NOi mus I be malled lo the following Dd<lress . Use the aUadled document lo s~mil the S 100 applicalior> ~e. Pluase nore lhat the NOi end apptlcalion lee are submitted $epara1etr to cWferent addresses . ----·------·----- Texas Commission on Environmental Quality Storm Water II. General Permils Team; MC. 228 f'.0. Box 13087 Austin, T'oxas 78711-308 7 OEEE .L3r~3S~'l dH ----------·-·---------· v . Design Report Waterline Fire Flow Analysis for Castlegate Subdivision -Section 5 -Phase 2 · College Station, Texas August 2004 Prepared By: TEXCON General Contractors 1707 Graham Road · College Station, Texas 77845 (979) 764-7743 1.0 INTRODUCTION & DESCIUPTION The purpose of thi s report is to pro v id e a de scription of th e propos e d wat e rlin es to be con s tru c ted with the Castlegate Subdivision, Sectiou 5, Phase 2, and to pro v id e th e res ult s of th e analysis of the waterlines und e r fire flow c onditions. An existin g 12" wa terlin e is located along Castlegate Drive adjacent to the project site . The proposed wate rlin e to supply the site will connect to existin g 8" waterlines previously constructed with the Se ction 5, Pha se 1 developme nt. The water main will b e c onstructe d using 8" and 3" diam e te r pip e . The 8" waterline for this project will be constru c ted of DR-14 , PVC pipe mee ting the requirements of A WW A C-909 with mechanical joint fittings . The 3" pipe will be constructed of SDR-21, PVC pipe m e eting the re quirements of ASTM-2241 with mechanical joint fittings . 2.0 FIRE FLOW REQUIREMENTS The flow required for fire hydrant flow for the subdivision is 1,500 gallons per minute (gpm), which can be split between 2 adjacent fire hydrants . 3.0 WATERLINE SYSTEM ANALYSIS The waterline system was analyzed using the WaterCAD computer program developed by Haestad Methods, Inc . Exhibit" l" is a schematic of the proposed waterline for Phase 2 and the existing Phase 1 waterline, which shows the locations of the fire hydrants. The 3" diameter line only has domestic use so it was not shown or included in the model for the fire flow analysis . A normal domestic use flow of 1.5 gpm was included in the analysis for each residential lot in Section 5 (102 lots) and the future Section 6 (23 lots). This results in a normal demand of 188 gpm, which was included in the analysis. The residual pressure in the existing 12 " waterline was determined by calculating the headloss at a flow of 1,688 gpm for the existing line . Exhibit "6" presents the results of a pressure/flow test from fire hydrants connected to the existing 12" waterline along Castlegate Drive. A static pressure of 90 psi and a residual pressure of 85 psi with the hydrant flow at 1, 140 gpm were determined by C ollege Station Public Utility personnel. The residual pressure of 79 .6 psi at a flow of 1,688 gpm was calculated using the following equation: Where : QR = Q available @ desired residual pressure QF = Q during fir e flow test HR = pressure drop to desired residual pressure HF = pre ssure drop during fire flow test This results in a residual pressure of 79 .6 psi where the existing 8" waterline connects to the 8" stub on the 12 " waterline. The hydraulic grad e was set at this pressure at th e stat1 of th e proposed waterlin e, Junction R-1 . The c omputer mod e l wa s run with a fir e flO\·V o f 7 50 gpm for e ach of th e 2 tire hydrants propo sed for this project. Exhibit "2" is a summary of th e pipe system junction nod es for thi s sce nario. Th e lo wes t res idual press ure occ urred in th e sys te m at Jun c tion J -16 . Th e press ur e at thi s po int is es tim a ted by th e mo de l to be 69 .1 ps i, w hi c h excee d s th e minimum of 20 ps i re quire d by th e TCEQ regul a ti o ns. An 8" waterline is being stubbed out for the future Section 6 development. An additional scenario with 1500 gpm fire hydrant flow on Pipe 31, which will serve Section 6, was modeled . Exhibit "3" is a summary of the pipe system junction nodes for this scenario. The lowest residual pressure occurred in the system at Junction J-29 . The pressure at this point is estimated by the model to be 65 .5 psi, which exceeds the minimum of 20 ps i required by the TCEQ regulations. Exhibits "4" & "5" are summaries of the pipe sections for the system under this demand scenario . The maximum velocity for the 8" water mains is 9.80 feet per second, and occurs in Pipe P-31 . A separate analysis was not run for the peak domestic use. Since the residual pressure for the fire flow analysis exceeds the minimum pressure of 35 psi required by TCEQ . Minor losses in this system were not calculated, as they were assumed to be insignificant. 4.0 CONCLUSIONS The waterlines proposed for this development should adequately provide the fire flow required with acceptable values for headloss and velocity. This analysis was done assuming adequate residual pre-ssure in the existing 12" water main, as determined by the flow test. Prior to the Section 6 development, an additional flow test on the Section 5 water mains will be performed to verify the residual pressure assumptions. R-1 P-30 P -1 J -1 P-2 J-2 P -3 P -5 J-5 P-6 -6 FH~1 P-7 J-7 P -8 J-8 P -9 J-9 P-10 J -1 0 P-11 J-1 1 P-3 1 J -29 T itl e: Cas tl ega te - S ecti on 5 -P h ase 2 c:lh aes tadl w t rc\e 114 .wcd J-2 7 J-22 P -12 06116104 10:59:50 AM © H aestad M e lhocl s. Inc. Scenario: Base J-26 P -28 P-25 J-2 0 P-22 J -16 P-16 P-15 J -1 5 J-1 3 J-1 4 FH -Ii z.. TEXCON GENERAL CONTRACTORS 37 Brooks ide RoacJ Wa te rbury . CT 06708 USA P-20 J -19 J -1 8 J -1 7 P -17 Ex h:b:f-1 Project Eng ineer : JOE SC HU LTZ Wa terCAD v3 . ·1 i 071cl (203 ) 755-1 666 Paqe 1 o f 1 Node Eleva tio n Dema nd La be l (ft) Type J-1 3 08.40 d emand J -2 3 07 .70 d e mand J -3 3 0 9.81 d ema n d J-4 3 11.26 d emand J-5 31 3 .19 d eman d J-6 314.97 demand J -7 315.04 d emand J -8 316.80 d ema nd J-9 319.73 d e m a nd J-10 321 .21 demand J-11 321 .60 d e mand J-1 2 320.68 demand J-13 320 .55 d e mand J -14 320.42 deman d J-15 320.51 demand J -16 324.40 demand J -17 319.03 demand J -18 319.0 9 demand J-19 319.12 demand J-20 324 .8 6 demand J-21 323 .55 demand J-22 315.69 demand J-23 311.48 demand J -24 320.62 demand J-25 319.79 d e mand J-26 319.79 demand J-27 315.64 demand J -28 31 0 .78 d e mand J -29 322.42 demand Till e: Castl eg a te -Sec ti o n 5 - P hase 2 c:ll1 aesl a dl wlrcle 114 .wcc l Dema nd (gpm) 0 .0 0 0 .00 0 .00 10 .00 0 .00 23 .0 0 7 5 0 .00 10 .00 0 .00 20 .00 0 .00 12 .00 750.00 0 .00 0 .00 20 .00 20 .00 0 .00 0 .00 20 .00 0.00 18.00 0 .00 0 .00 0 .00 0 .00 0 .00 0 .00 35 .00 061 1610 4 11:00:14 AM © Haes ta cl Me t11ocls. Inc . Scenario: Base Steady State Analysis Junction Report Dema nd Ca lcu la ted Hydraulic Press ure Pa tt e rn Deman d G rade (p si ) (gp m ) (ft) Fixed 0 .00 4 91 .42 79.14 Fixed 0 .00 490 .9 1 7 9 .2 3 Fixed 0 .00 488.72 77 .37 Fixed 10.00 4 88.18 7 6.51 Fixed 0.00 4 85.83 74 .65 Fixed 23.00 483 .60 72 .92 Fixed 750.00 4 83 .52 72 .8 6 Fixed 10 .00 4 8 3 .30 72.00 Fixed 0 .00 483 .11 70.65 Fi xe d 20.00 483 .01 69.97 Fi xe d 0 .00 482.98 69.79 Fi xed 12.00 482.67 70.05 Fi xed 7 5 0 .00 482.65 70.10 Fi xe d 0 .00 482 .73 70.19 Fi xed 0 .00 482.91 70.23 Fi xed 2 0 .00 484.09 69.05 ---Fi xed 20 .00 486.04 72.22 Fixed 0 .00 486.22 72.27 Fi xed 0 .00 486.30 72.29 Fixed 2 0 .00 488.87 70.92 Fi xed 0 .00 489.03 71 .56 Fixed 18.00 488.87 74 .89 Fi xed 0 .00 488.78 76.67 Fi xed 0 .00 490.78 73.58 Fi xed 0 .00 491 .03 74 .05 Fi xed 0 .00 491.48 74.24 Fix ed 0 .00 491 .65 76.11 Fi xed 0 .00 491 .85 78.30 Fix ed 35.00 482 .98 69.43 TEXCON GE N ER AL CONTR A CTOR S 37 Br oo k si de l ~o;"!ll WaterlJury, C T 06708 USA Project E ng in ee r : JOE SC HUL TZ Wa te rCA O v3 . t [07 1c l (203 ) 755-1666 Node Elevation D e man d Labe l (ft) Type J -1 308.40 d e ma nd J -2 30 7 .70 d e ma nd J -3 309.81 d e ma nd J -4 311 .26 d e ma nd J-5 313 .19 d eman d J -6 3 14 .97 d ema nd J-7 315 .04 dema nd J -8 3 16 .80 demand J-9 319.73 demand J-10 321 .21 demand J-11 321.60 demand J-12 320 .68 demand J-13 320.55 demand J-14 320.42 demand J-15 320 .51 demand J-16 324.40 demand J-17 319.03 demand J-18 319.09 demand J-19 319.12 demand J-20 324.86 demand J-21 323 .55 demand J-22 315.69 demand J-23 311.48 demand J-24 320 .62 demand J-25 319.79 demand J-26 319.79 demand J-27 315.64 demand J -28 310.78 demand J -29 322.42 demand Ti ll e: Ca sll ega te -Sec tio n 5 -Pflase 2 c :lfl aesta dl wtrcle 1 14 .wcd De ma nd (g p m) 0 .00 0 .00 0 .00 10 .00 0 .00 2 3 .00 0 .00 10.00 0 .00 20 .00 0.00 12 .00 0 .00 0 .00 0 .00 20.00 20.00 0 .00 0 .00 20.00 0.00 18.00 0 .00 0 .00 0 .00 0.00 0.00 0.00 1 ,535.00 061 16/04 11 :0 1 :27 AM © Ha es tact Metflods. tn c. Scenario: Base Steady State Analysis Junction Report D e ma nd C a lcula ted Hydra ul ic Pre ssure Pattern De m a nd Grad e (p si) (g p m) (ft) Fi xe d 0 .00 491 .4 3 79.15 Fixed 0 .00 490 .94 79 .2 4 Fi xed 0 .00 488 .80 77.40 Fi xe d 10 .00 488.3 2 76.57 Fi xe d 0 .00 486 .23 74 .8 3 Fi xe d 23 .00 4 84 .26 73 .21 Fi xed 0 .00 484 .19 73 .15 Fi xed 10.00 482.24 71 .54 Fixed 0 .00 480.4 4 69.50 Fixed 20 .00 479.53 68.46 Fixed 0 .00 479 .27 68.18 Fixed 12 .00 480.93 69.30 Fixed 0 .00 481 .03 69.40 Fixed 0 .00 481 .13 69.49 Fixed 0 .00 481 .36 69 .56 Fixed 20.00 482.83 68.51 Fixed 20.00 485.26 71.88 Fixed 0 .00 485.48 71 .95 Fixed 0 .00 485.58 71 .98 Fixed 20.00 488.75 70.87 Fixed 0 .00 488.95 71 .53 Fixed 18.00 488 .87 74.89 Fixed 0 .00 488.82 76.69 Fixed 0 .00 490.75 73.57 Fixed 0 .00 491 .01 74.04 Fixed 0 .00 491.46 74 .24 Fixed 0 .00 491.64 76.11 Fixed 0 .00 491 .84 78.30 Fixed 1,535.00 473.91 65.51 TEX CO N GE NERAL CONTR ACTOR S 3 7 Brooksicle Rocirt Wat e rb ur y. CT 06708 USA Project Engineer : JOE SCHULTZ Wa l e rCAD v3 . I 107 l cl (203) 755-1 666 Page I of I Scenario: Base Steady State Analys is Pipe Report Link Length Diameter Mate rial Roughnes! Minor LOS! Initi al Current Di scharge Start End Label (ft) (in) P-1 49 .00 8 PVC P-2 43 .00 8 PVC P-3 185 .00 8 PVC P-4 33 .00 8 PVC P-5 146.00 8 PVC P-6 138.00 8 PVC P-7 5 .00 8 PVC P-8 142.00 8 PVC P-9 134 .00 8 PVC P-10 68 .00 8 PVC P-11 20 .00 8 PVC P-12 321.00 8 PVC P-31 172 .00 8 PVC P-13 19.00 8 PVC P-14 18.00 8 PVC P-15 43 .00 8 PVC P-16 275 .00 8 PVC P-17 426 .00 8 PVC P-18 36 .00 8 PVC P-19 17 .00 8 PVC P-2 0 524 .00 8 PVC P-21 32 .00 8 PVC P-22 235.00 8 PVC P-25 197.00 8 PVC P-23 166.00 8 PVC P-24 99 .00 8 PVC P-26 28 .00 8 PVC P-27 50 .00 8 PVC P-28 138.00 12 PVC P-29 162.00 12 PVC P-30 125 .00 12 PVC Titl e : Ca s ll ega te -Secti on 5 -Ph ase 2 c:lhaes tadlw trcle 114 .w ccl 150 .0 150 .0 150.0 150 .0 150 .0 150 .0 150 .0 150.0 150.0 150.0 150.0 150.0 150.0 150.0 150.0 150.0 150.0 150.0 150.0 150.0 150.0 150.0 150.0 150.0 150.0 150.0 150.0 150.0 150.0 150.0 150.0 061 16/04 11 .20 :22 AM © Haes lad Meth ods. Inc . S tatu s Status (g pm) Hydraul ic Hydraulic G rade Grade (ft) (ft) 0 .00 Open Open 898 .07 492 .00 491.43 0 .00 Op en Open 898 .07 491 .43 490.94 0 .00 Open Open 898 .07 490.94 488.80 0 .00 Open Open 1,017 .22 488 .80 488.32 0 .00 Open Open 1,007 .22 488 .32 486.23 0 .00 Open Open 1,007 .22 486 .2 3 484.26 0 .00 Open Open 984 .22 484 .26 484 .19 0 .00 Open Ope n 984 .22 484 .19 482.24 0 .00 Ope n Open 974 .22 482.24 480.44 0 .00 Open Open 974 .22 480.44 479 .53 0 .00 Open Open 954 .22 479 .53 479-27 0.00 Open Open -580 .78 479.27 480.93 0 .00 Open Open 1 ,535 .00 479 .27 473 .91 0 .00 Open Open -592 .78 480 .93 481 .03 0.00 Open Open -592 .78 481 .03 481.13 0 .00 Open Open -592.78 481 .13 481 .36 0.00 Open Open -592 .78 48 1.36 482.83 0 .00 Open Open -612 .78 482 .83 485.26 0 .00 Open Open -632 .78 485-26 485.48 0 .00 Open Open -632 .78 485.48 485.58 0.00 Open Open -632 .78 485 .58 488.75 0 .00 Open Open -652 .78 488 .75 488.95 0 .00 Open Open 137.14 488.95 488.87 0 .00 Open Open -789 .93 488 .95 490 .75 0 .00 Open Open 119.14 488 .87 488.82 0 .00 Open Open 119.14 488.82 488.80 0 .00 Open Open -789.93 490 .75 491 .01 0 .00 Open Open -789.93 49 1.01 491.46 0 .00 Open Open -789 .93 491.46 491 .64 0 .00 Open Open -789.93 491 .64 491 .84 0 .00 Open Open -789 .93 491.84 492.00 TEXCON GENER AL CONTRACTORS 37 Brooks1cle Roacl Walertiury. CT 06708 USA Head loss (ft) 0 .57 0.50 2.14 0.48 2 .09 1.97 0 .07 1.94 1.80 0 .91 0 .26 1.66 5 .36 0 .10 0 .10 0-23 1.47 2.43 0 .22 0 .10 3 .17 0-21 0 .08 1.80 0 .05 0.03 0 .26 0.46 0 .1 7 0 .21 0 .16 Friction S lope (ft/1 OOOft) 11 .56 11 .56 11 .56 14 .56 14 .29 14 .29 13 .70 13 .70 13.44 13.44 12 .93 5 .16 31 .17 5 .36 5 .36 5 .36 5.36 5 .70 6.05 6 .05 6 .05 6.41 0.36 9 .1 2 0-28 0.28 9.12 9 .12 1.27 1.2 7 1.2 7 Project Eng in ee r : JOE SC HU LTZ Wa te rCAD v3 . 1 107 t c J (203 ) 7~>5-IGGG Page 1 of 1 Label Status Constituent (mg /I) Flow (gpm) P-1 Open P-2 Open P-3 Open P-4 Open P -5 Open P-6 Open P-7 Open P-8 Open P-9 Open P-10 Open P-11 Open P-12 Open P-13 Open P-14 Open P-15 Open P-16 Open P-17 Open P-18 Open P-19 Open P-20 P-21 P-22 P-23 P-24 P-25 P-26 P-27 P-28 P-29 P-30 Open Open Open Open Open Open Open Open Open Open Open P-31 Open NIA 898.07 NIA 898 .07 NIA 898.07 NIA 1 ,017 .22 NIA 1,007 .22 NIA 1 ,007.22 NIA 984.22 NIA 984.22 NIA 974 .22 NIA 974 .22 NIA 954.22 NIA -580.78 NIA -592 .78 NIA -592.78 NIA -592 .78 NIA -592 .78 NIA -612.78 NIA -632.78 NIA -632 .78 NIA NIA NIA NIA NIA NIA NIA NIA NIA NIA NIA -632.78 -652.78 137.14 119.14 119.14 -789.93 -789.93 -789.93 -789.93 -789.93 -789.93 NIA 1 ,535.00 Ti tl e: Cas tl ega te -Secti on 5 -P t1 ase 2 c :l haestad l wtrcl e 114. wed Analysis Results Scenario: Base Steady State Analysis Pipes @ 0.00 hr Velocity (fVs) From Grade (ft) To Grade (ft) Friction Loss (ft) Minor Tota l Headloss Loss Headloss Gradient (ft) (ft) (fU1 OOOft) 5 .73 492.00 491.43 5 .73 491.43 490.94 5.73 490 .94 488.80 6 .49 488.80 488.32 6.43 488.32 486.23 6.43 486.23 484 .26 6.28 484 .26 484 .19 6 .28 484 .19 482 .24 6.22 482.24 480.44 6 .22 480.44 479.53 6 .09 479.53 479.27 3 .71 479.27 480.93 3 .78 480.93 481 .03 3 .78 481.03 481 .13 3.78 481 .13 481 .36 3.78 481.36 482 .83 3 .91 482.83 485.26 4 .04 485.26 485.48 4 .04 485.48 485.58 4 .04 485 .58 488.75 4 .17 488.75 488.95 0 .88 488.95 488.87 0 .76 488.87 488.82 0 .76 488.82 488.80 5 .04 488.95 490.75 5.04 490.75 491.01 5 .04 491 .01 491 .46 2 .24 491.46 491 .64 2.24 491.64 491 .84 2 .24 491 .84 492 .00 JU!Q.. 479.27 473 .91 0 .57 0 .00 0 .50 0 .00 2.14 0.00 0.48 0 .00 2 .09 0.00 1 .97 0 .00 0.07 . 0 .00 1 .94 0.00 1 .80 0 .00 0 .91 0 .00 0 .26 0 .00 1 .66 0 .00 0 .10 0 .00 0 .10 0.00 0 .23 0 .00 1.47 0 .00 2 .43 0.00 0 .22 0 .00 0 .10 0 .00 3 .17 0 .21 0 .08 0 .05 0 .03 1 .80 0.26 0.46 0 .17 0 .21 0 .16 0 .00 0.00 0 .00 0 .00 0 .00 0 .00 0 .00 0 .00 0 .00 0 .00 0.00 5 .36 0.00 TEXCON GEN ERAL CONTRACTORS 0 .57 0 .50 2 .14 0.48 2 .09 1 .97 0 .07 1 .94 1 .80 0 .91 0 .26 1 .66 0 .10 0 .10 0.23 1.47 2.43 0 .22 0 .10 3 .17 0 .21 0 .08 0 .05 0 .03 1.80 0 .26 0.46 0 .17 0 .21 0 .16 5.36 11 .56 11 .56 11 .56 14 .56 14 .29 14 .29 13.70 13.70 13.44 13.44 12.93 5 .16 5 .36 5 .36 5 .36 5 .36 5 .70 6.05 6 .05 6 .05 6.41 0.36 0 .28 0.28 9.12 9.12 9 .12 1 .27 1 .27 1 .27 31.17 Proj ect E ng inee r : JOE SC HULTZ Wa terCAD v3 . 1 [071 cJ 06116/04 11 :0 1 :44 AM © H a e s tad M e thods. tn c . 37 Broo ksic!e Roacl W a te rbury. C T 067 08 USA (2 03) 755-1 6 6 6 Page 2 03/04/2004 12:38 FAX 979 764 34 52 COLLEGE STATION PUB .UTL . 1601 GRAHAM ROAD COLLEGE STATION TEXAS 77845 Date: 4 MARCH 2004 Nwnber pages including cover sheet -1 Fax to: 764-7759 Attention: JOE SCHULTZ Company: TEXCON From: Butch Willis Water Wastewater Division Phone : 979-764-3435 Fax: 979-764-3452 FLOW TEST REPORT Location: CASTLE GATE DRIVE Flow hydrant number: V-035 Pitot reading: 80 (GPM): 1140 Static hydrant number: V-036 Static PSI: 90 Residual PSI: 85 14!001 Design Report Proposed Sanitary Sewer Line Improvements for Castlegate Subdivision Sections 5 & Future Section 6 College Station, Texas July 2004 Prepared B y: TEXCON General Contractors 1 707 Graham Road College Station, Texas 77845 (979) 764-7743 1.0 INTRODUCTION & DESCRIPTION The purpose of this report is to provide a description of the proposed sanitary sewer to be constructed with the Castlegate Subdivision Section 5 & future Section 6 , and to provide the criteria used in the design of this sanitary sewer system. The project will include th e construction of approximately 4 ,418 feet of sanitary sewer line. The lin e wi ll service the proposed development of the Cast legate Subdivision, Section 5, Phases l & 2, as well as the future development of S ec tion 6. 2.0 SANITARY SEWER -Design Flow and Pipe Size Calculations The proposed sewer line is to be constructed of 6" and 8" diameter SDR-26, PVC pipe which meets the requirements of ASTM-D3034 . The proposed manholes are 4' diameter manholes, and vary from 7' to 16' in depth, with sewer line slopes ranging from 0.4% to 2.5%. The maximum distance between manholes is less than 500 feet, as required by the Texas Commission on Environmental Quality (TCEQ). The minimum allowable slopes for 8" and 6" pipes per TCEQ requirements are 0 .33% and 0 .50 %, respectively . All construction shall meet the current City of College Station Standard Specifications for Sanitary Sewer Construction . The sewer line information is summarized in Table 1. 3.0 DETERMINATION OF PEAK FLOW VALUES The peak flows were based on using a daily use of 300 gallons per day for each dwellin g unit. The design peak flow is determined by multiplying the average daily flow by 4 .0 , which results in the peak hourly flow. The velocities for the lines were calculated using Manning 's Equation . According to the TCEQ , the minimum velocity for sewer systems flowing full is 2.0 feet per second. As shown in Table l, the minimum anticipated flow velocities for the proposed sewer lines at 50% full meet this requirement. The flow for l 00% full will not be less than the flow for 50% full; therefore, the TCEQ requirement is met. The TCEQ requires that the maximum velocity for sewer systems flow full not exceed 10 feet per second. The values in Table l are well below this maximum ve locit y. T ABLE 1 -S E W E R LINE FLOW DAT A ci Manhole No . o f U nits From Cumulat ive Average Percent 50 % Fu ll z Size Length Slope Peak Flow Q) Number Dwe llin g Unit Mergi ng Dwellin g Daily Flow Full Flow c: :J From To (i n) (ft) (%) Services Lines Uni ts (gpm) (cfs) (cfs) (%) (cfs ) If 5-16 5-12 8 234 .9 0.40 1 23(Sec t 6) 24 5.00 0 .01 11 0 .0445 16 .4 0 .3821 VJ "'i" 5-15 5-14 6 3 13.6 2.14 10 -10 2 08 0.0046 0 .0186 10 .4 0.4104 VJ 5-14 5-9 6 173.4 1.00 5 -15 3.12 0 .0070 0.0278 15.1 0 .2806 M 5-8 5-7 6 31 4 .4 1.98 11 -11 2.29 0.0051 0 .0204 11 .1 0 .3948 J, 5-7 5-2 6 113 .6 2 .1 5 1 -12 2.50 0.0056 0 .0223 11 .3 0.4114 5-6 5-5 6 476 .9 1.52 13 -13 2.71 0 .006 0 0 .024 1 12 .8 0 .3459 5-5 5-4 8 300 .9 0 .40 9 -22 4 .58 0 .0102 0 .0408 15 .7 0 .3821 N 5-4 5-3 8 338.7 0 .40 6 28 5.83 0 .0 130 0 .0 52 0 17 .7 0 .3821 J, - 5-3 5-2 8 234 .1 0 .40 6 -34 708 0.0 158 0 .063 1 19.4 0 .3821 5-2 5-1 8 37 3 .9 1.81 8 12(S-3) 54 11 .25 0 .025 1 0 .1002 16 .8 0 .8 129 5-13 5-1 2 6 251 .4 2 .50 8 -8 1.67 0 .0037 0 .0 148 9 .0 0.4436 5-12 5-11 8 453.4 0.40 10 24(S-5) 42 8 .75 0 .0 195 0 .0780 2 1.6 0 .3821 ...... 5-1 1 5-10 8 160 .5 0 .40 6 -48 10.00 0.022 3 0 .08 9 1 23.1 0 .382 1 J, 5-10 5-9 8 22 7 .1 0 .4 0 4 -52 10 .83 0.024 1 0 .0 96 5 24 .0 0 .382 1 5-9 5-1 8 255 .6 1 .00 3 15(S-4) 70 14 .58 0 .0325 0 .1299 22 .1 0 .6 042 5-1 Exis ting 8 195 .9 1.40 1 54 (S-2) 125 26 .04 0.058 0 0 .232 0 27.2 0 .7149 n = 0 .01 3 R efer to cons tru c ti o n d rawing s fo r manhol e lo cat ions. 4.0 CONCLUSIO NS It is our d etermin ation based on the criteria and d ata d evelop ed th at th e propo sed sewer li ne will prov id e su ffi ci e nt cap acity for the anticip ated was tewater flo w s generated b y th is d eve lopm e nt and the fu ture d eve lopme nt o f Sectio n 6 . Ve locity (fps) 2 .2 4 .2 2 .9 4 .0 4 .2 3 .5 2 .2 2.2 2.2 4 .7 4 .5 2.2 2 .2 2.2 3.5 4 .1 Drainage Report for Castlegate Subdivision -Section 5, Phase 2 College Station , Texas June 2 0 04 Developer: Greens Prairie Investors, Ltd. By Greens Prairie Associates, LLC 4490 Castlegate Drive Co ll ege Station, Texas 778 4 5 (979) 690 -7250 Prepared By: TEXCON General Contractors 1 707 Graham Road College Station , Texas 77845 (97 9) 764-7 743 CERTIFICATION I, Joseph P. Schultz, Licensed Professional Engineer No. 65889 , State of Texas , certify that this report for the drainage design for the Castlegate Subdivisiou -Section 5, Phase 2, was prepared by me in accordance with the provisions of the City of College Station Drainage Policy and Design Standards for the owners hereof. Gi ( TABLE OF CONTENTS DRAINAGE REPORT CASTLEGATE SUBDIVISION -SECTION 5, PHASE 2 CERTIFICATION .................................................................................................................................................................. 1 TABLE OF CONTENTS ........................................................................................................................................................ 2 LIST OFT ABLES .................................................................................................................................................................. 2 INTRODUCTION ................................................................................................................................................................... 3 GENERAL LOCATION AND DESCRIPTION .................................................................................................................. 3 FLOOD HAZARD INFORMATION .................................................................................................................................... 3 DEVELOPMENT DRAINAGE PATTERNS .................................... .-.................................................................................. 3 DRAINAGE DESIGN CRITERIA ........................................................................................................................................ 3 STORM WATER RUNOFF DETERMINATION .............................................................................................................. .4 DETENTION FACILITY DESIGN ...................................................................................................................................... 5 STORM SEWER DESIGN .................................................................................................................................................... 7 CHANNEL DESIGN .............................................................................................................................................................. 7 CONCLUSIONS ..................................................................................................................................................................... 8 APPENDIX A .......................................................................................................................................................................... 9 Time of Concentration Data & Calculatio11s APPENDIX B ........................................................................................................................................................................ 12 Storm Sewer Inlet Desig11 Calculatio11s APPENDIX C ........................................................................................................................................................................ 15 Storm Sewer Pipe & Flume Design Calculations APPENDIX D ........................................................................................................................................................................ 22 Dete11tio11 Pond Design Data & Calculations EXHIBIT A ............................................................................................................................................................................ 27 Pre-& Post-Development Drainage Area Maps EXHIBIT B ............................................................................................................................................................................ 29 Post-Development Drainage Area Map -Storm Sewer Design LIST OF TABLES TABLE l -Rainfall Intensity Calculations .......................................................................................... 4 TABLE 2 -Time of Concentration (tc) Equations .............................................................................. 5 TABLE 3 -Pre-& Post-Development Runoff Information -Detention Evaluation ....................... 5 TABLE 4 -Post-Development Runoff Information -Storm Sewer Design ..................................... 5 TABLE 5 -Pre-& Post-Development Runoff Comparison -Detention Pond Design .................... 6 TABLE 6 -Summary of Maximum Pond Water Levels .................................................................... 6 2 DRAINAGE REPORT CASTLEGATE SUBDIVISION -SECTION 5, PHASE 2 INTRODUCTION The purpose of this report is to provide the hydrologi c al effects of the construction of th e C<tstlegate Subdivision -Section 5, Phase 2, and to ve rify that the proposed stom1 drain age system m e ets the requirements se t forth by the City of College Station Drainage Policy and De si g n Sta ndards . GENERAL LOCATION AND DESCRIPTION The project is located on a portion of a 111.46 acre tract located west of State Highway 6 along the north side of Greens Prairie Road in College Station, Texas. This report addresses Phase 2 of Section 5 of this subdivision, which is made up of 13 .51 acres . Section 5 is located adjacent to Castlegate Section 4 along Castlegate Drive. The site is predominantly wooded . The existing ground elevations range from elevation 314 to elevation 332. The general location of the project site is shown on the vicinity map in Exhibit A . FLOOD HAZARD INFORMATION The project site is located in the Spring Creek branch of the Lick Creek Drainage Basin, with a portion in the Peach Creek Drainage Basin. Most of the proposed developed area of the site is located in a Zone X Area according to the Flood Insurance Rate Map prepared by the Fed e ral Emergency Management Agency (FEMA) for Brazos County, Texas and incorporated area s d a ted February 9 , 2000, panel number 48041 C0205-D . This area is shown on E xhibit A as th e 100-year floodplain limit. Also shown on this exhibit are th e floodway limits as determin ed by the Castlegate Floodplain Analysis Report which was previously submitted . The Flood Haz ard Area within this development has been designated as Greenway Area, which will have no d e velopment and it will be left in its current condition. DEVELOPMENT DRAINAGE PATTERNS Prior to d eve lopment, the storm water runoff for S ec tion 5 , Phas e 2 flo ws in two diffe re nt di re ctions . A majority of th e runoff fl ows in a north wes te rl y direc tion until it e nt e rs a tri b uta ry of Spring C reek . U ltima te ly, thi s runo ff flow s int o Sprin g Creek a nd th e n north to th e p roposed reg ion a l dete ntion fa cility . R efe r to th e v ic init y m a p in Ex hibit A for th e locati o n of thi s reg ion a l dete ntion facility . The re m a ind e r of th e run o ff from thi s s it e fl ows in a so uth e rl y direc ti o n int o th e G ree n s Prairi e Road ri g ht -of-way a nd th e n int o a t ribut a ry of P eac h C reek . DRAINAGE D ESIGN CRITERIA . T he d e si g n p a ra me te rs fo r th e s to rm se w e r a nd d e te n ti o n fa c ility a na lys is a re as fo ll ow s: • Th e Rat io na l M e th o d is utili z ed to d e te rmin e pe ak s to rm wa te r run o ff ra tes fo r th e s to rm se w e r d e ig n, a nd th e H EC-I co m pu te r p ro g ra m is utili zed to d e te r m in e pe ak s to rm wa te r run o ff ra tes fo r th e d e te nti o n fa c ili ty d es ig n . • D es ig n St o rm F req ue nc y S to rm se w e r sys te m I() a nd I 0 0 -yea r s to rm eve nt s Detention facility analysis • Runoff Coe ffici en ts 5, I 0 , 25 , 50 and 100-year storm eve nts Pre-d eve lopment Post-development (single family residential) • Runoff Curve Number (CN) -Detention Pond c = 0 .30 c = 0.55 The Brazos County Soil Survey shows the soils in the area to be classifi ed as hydrolo g ic group D soils . The pre-development CN is based on no development on the site . The post-development CN is based on development of Phase lofthe subdivi sion within the det ention pond drainage area . The CN calculations are found in Appendix 0 . • Rainfall Intensity equations and values for Brazos County can be found in Table 1. • Time of Concentration, tc -Calculations are based on the method found in the TR-55 pu bl ication. Refer to Table 2 for the equations and Appendix A for calcu lations . The runoff flow paths used for calculating the pre-& post-development times of concentration for the detention pond analysis are shown on Exhibit A, and the flow path used for the post- development time of concentration for the storm sewer design is found on Exhibit B. For smaller drainage areas, a minimum tc of 10 minutes is used to determine the rainfall intensity values . STO RM WATER R UNO FF DETERMI NATI O N The peak runoff values were determined in accordance with the criteria presented in the previous section for the 5, 10, 25, 50, and 100-year storm events. The drainage areas for the pre-& post-deve lopment conditions for the detention pond analysis are shown on Exhibit A. The drainage areas for the post-development conditions for the storm sewer design are shown on Exhibit B. Pre-development and post-development runoff information for the detention facility evaluation are summarized in Table 3. Post-development runoff conditions for the storm sewer design are summarized in Tab le 4. TABLE 1 -R ai nfall Inte nsity Calc ul ations Rainfall I ntens ity Valu es (i n /h r) Sto rm l e = Event 10 min Is 7.693 110 8 .635 '2 s 9 .861 lso 11 .148 1100 11 .639 Brazos Co unty: 5 'f_ear s torm 10 'i.ear storm b= 76 b= 80 d = 8.5 d = 8.5 e= 0 .78 5 e= 0.763 I = b I (tc +d )0 I = Rainfall Intensity (in/hr) tc = L/(V*6 0 ) le =Time of concent ration (min) L = Length (ft) V = V elocity (ft/sec) 25 'i_ear s torm 50 'i.ear s to rm 100 'f_ea r s torm b= 89 b= 98 b= 96 d= 8.5 d= 8.5 d= 8.0 e= 0 .7 54 e= 0.7 45 e = 0.730 (Data take n fr om St a te D epartment of Highwa'i_s and Public Transpo11a tion H'i_drau lic Manual , page 2-1 6) TABLE 2 - T im e of Concentration (tc) Eq uation s The tim e of concentration was determin ed usi ng m e thods found i11 TR -5 5, "Urban Hy dro logy for Sma ll Wat ers heds." The equ ati ons a re as follows: Time of Concentration : For Sheet Flow : Tc = T t(s hee t now)+ Tt(co nc e ntrated s he e t n ow) w here : T 1 =Travel Time , minute s 0.007 (n L)0 ·8 (Pi)o .s so .4 w here : T 1 = trave l time, hours n =Manning 's roughness coefficient . L = flow length , feet P 2 = 2-year, 24-hour rainfall = 4 .5" s = land slope , ft/ft For Shallow Concentrated F lo w : T, =LI (60*V) Refer to Appendix A for calculations. where: T 1 = travel time , minute s V = Velocity, fps (See Fig 3-1 , App . E) L = flow len gt h, feet TABLE 3 -Pre-& Post-Development Runoff Information -Detention Evaluation Area# Area CN tc L (acres) (min) (hrs) Pre 101 6.30 75.6 28 .1 0 .281 Post 205 3.70 83 .5 17 .5 0 .175 Post 206 0.26 83 .5 10 .0 0 .10 Post 207 0.13 75 .8 10.0 0 .10 Post 208 2.37 79 .5 10 .0 0 .10 TABLE 4 -Post-Development Runoff Information -Storm Sewer Design Area t c 5 year storm 10 year storm 25 year storm 50 year storm 100 year storm Area# c Is Os 110 0 10 l2s 0 2s lso O so 1100 0 100 (acres) (min) (in/hr) (cfs) (in/hr) (cfs) (in/hr) (cfs) (in/hr) (cfs) (in/hr) (cfs) 8 1.37 0 .55 17.5 5.889 4.44 6 .66 0 5.02 7 .630 5.75 8.65 1 6 .5 2 9.026 6.80 9 0 .90 0 .55 10 7.693 3.81 8.635 4 .27 9 .86 1 4 .88 11.148 5 .5 2 11.639 5.76 --- 10 0 .74 0.55 10 7.693 3.13 8.635 3.51 9.86 1 4 .0 1 11 .148 4 .54 11 .639 4.74 11 0.62 0 .55 10 7.693 2.62 8.635 2.9 4 9.86 1 3.36 11 .14 8 3.80 11.639 3.97 12 1.89 0 .55 10 7.69 3 8 .0 0 8 .6 35 8.98 9 .86 1 10.25 11 .14 8 11 .59 11 .639 12.10 --- 14 1.71 0 .55 10 7.693 7.2 4 8 .635 8.12 9.86 1 9.27 11.14 8 10.48 11 .639 10.95 ------ 15 2.06 0 .55 10 7.693 8.72 8.635 9.78 9.86 1 11 .1 7 11 .148 12 .63 11 .639 13.19 ------------ 16 2.12 0 .55 10 7.693 8.97 8.635 10.07 9 .86 1 11 .50 11 .14 8 13 .00 11 .639 13 .57 DETENT IO N FACILITY DESlGN T he d etention fac ilit y handl in g a po r tion o f th e run off from this sit e i s a r eg ion a l fa c ilit y des i g ned b y L.IA En g in ee rin g & Survey in g, In c. A l so. a d etenti o n pond was co nst r uc ted upst r eam of Cas t l ega te Drive to reduce the pea k fl ow r es ultin g fro m th e Cas t l ega t e development. The detention faci li ty is located adjacent to Spring C re ek prior to Spr in g Creek enterin g the State Highway 6 right-of-way. A detention faci lit y is also needed for the runoff that flows into the Greens Prairie Road right- of-way. A co mp arison of the pre-& post-development peak flow values for Discharge Point #2 shows an increase of 16 cfs in the runoff for the 100-year storm event, from 28 cfs to 44 cfs. Table 5 shows the increases in runoff for the other stonn events if there was not a detention pond to contro l the runoff. This increase in runoff is due to the development of Phase 2 of Section 5. Because of this increased runo ff, a detention pond is proposed, w hich wi ll reduce the peak runoff to less than or equal to th e pre-develo pment runoff, as the "Post-Developm ent with Pond" data in Table 5 shows . TABLE 5 -Pre-& Post-Development Runoff Comparison -Detention Pond Design Location Os 010 0 2s O so 0100 (cfs) (cfs) (cfs) (cfs) (cfs) Pre-Development Total @ Discharge Pt. 13 16 21 25 28 Post-Development without Pond Total @ Discharge Pt. 23 24 34 39 44 Post-Development with Pond Into Pond 20 24 30 34 38 Out of Pond 12 15 18 21 24 Total @ Discharge Pt. 13 15 19 22 25 The area-capac ity data and the depth-discharge d ata are pro vided in Appendix D. The detention pond grading plan is shown in the construction drawings. The pond discharge pipe is a 27" reinforced concrete pipe. This pipe is 61 feet in length, with a safety end treatment at the disch arge end. The pipe has a design slope of 0 .5%. The stonn sewer piping for the detention facility outlet pip e wi ll be R CP meeting the requirements of ASTM C-76, C lass III pipe. The top of the pond berm is at Elevation 324.5 . The peak flow o ut of the detention facility was d etenn in ed by the HEC-1 program with inlet co ntrol conditions for the pond discharge pipe . As shown in Table 5, the peak outflow from the detention faci lity is less than th e a ll owable peak outflow for the des ig n storm event. Ad dition ally, Table 6 presents the maxim um wat er su rfa ce in the pond for eac h stom1 event, as we ll as the amount of freeboard provided. TABLE 6 -Summary of Maximum Pond Water Levels Storm Event Water Surface Freeboard , Elevation , ft. ft. 5-year 322.73 1.8 10-year 322.98 1.5 ----- 25-year 323.24 1.3 --- 50-year 323.44 1.1 --- 100-year 323 .64 0.9 Note : Deten ti on Pond Top of Berm Elevation = 32 4.50 STORM SEWER DESIGN The storm sewer piping for this project has been selected to be Reinforced Concrete Pipe (RCP) meeting the requirements of ASTM C-76 , Class III pipe meeting the requirements of ASTM C-789 . The curb inlets and junction boxes will be cast-in-place concrete . Appendix B presents a summary of the stonn sewer inlet design parameters and calculations. The inlets were designed based on a l 0-year design stonn . As per College Station guidelines , the capacities of inlets in sump were reduced by l 0% to allow for clogging . Inlets for the residential streets were located to maintain a gutter flow depth of 5" or less . This design depth will prevent the spread of water from reaching the crown of the road for the l 0- year storm event. Refer to Appendix B for a summary of the gutter flow depths . The runoff intercepted by the proposed storm sewer inlets was calculated using the following equations. The depth of flow in the gutter was determined by using the Straight Crown Flow equation . The flow intercepted by Inlets 5-5 & 5-6 was calculated by using the Capacity of Inlets On Grade equation. These equations and resulting data are summarized in Appendix B. There are no Inlets in Sump for this phase of construction. The area between the right-of-way and the curb line of the streets will be graded as necessary to provide a minimum of 6" of freeboard above the curb line. This will ensure that the runoff from the 100-year storm event will remain within the street right-of-way. Appendix C presents a summary of the storm sewer pipe design parameters and calculations . All pipes are 18" in diameter or larger. For pipes with 18" and 24" diameters, the cross- sectional area is reduced by 25%, as per College Station requirements. A summary of how thi s was achieved is shown in Appendix C as well. The pipes for the storm sewer system were designed based on the 10-year storm event, and they will also pass the 100-year storm event. Based on the depth of flow in the street determined for the 100-year storm event , this runoff will be contained within the street right-of-way until it enters the storm sewer system. As required by College Station, the velocity of flow in the storm sewer pipe system is not lower than 2.5 feet per second, and it does not exceed 15 feet per second. As the data shows , even during low flow conditions , the velocity in the pipes will exceed 2.5 feet per second and prevent sediment build-up in the pipes . The maximum flow in the stom1 sewe r pip e sys tem will occur in Pipe No. SA. The maximum velocity for the pipe system in this d e ve lopm ent w ill be 8 .5 feet per second and will occur in Pipe No. 6 . Appendix C contains a summ a ry o f th e pipe calculations as well as flow diagrams mapping the flows through th e stotm sew e r sys tem for the l 0 and l 00 -year eve nts. CHANNEL DESIGN The storm runoff from th e s tr ee t is con veyed to th e d e tention pond by a con c rete c hann e l. T he c hann e l is 7 fee t wid e and I 0" d ee p w ith a s lop e o f 1.5%. Th e ve lo c it y and d e pth fo r the I 0- a nd 100 -yea r s torm eve nt s a re 7 .5 fp s at 6.0 " d ee p and 8.4 fps at 7.3" d ee p, res pec ti ve ly. The ve locit y in th e ch ann e l w ill be di ss ip ated b y th e co ns tructi o n o f di ss ip ate r bl ocks in th e chan ne l after it d ro ps int o th e d ete nti o n po nd. A 6 fee t w id e con c rete flum e is prop osed to co nve y th e minor fl ows dir ec tl y to th e po nd o utl e t p ip e . 7 CONCLUSIONS The construction of this project will increase the storm water runoff from this site . The proposed stonn sewer system should adequately control the runoff and release it into existing drainages . As shown in the Castlegate Floodplain Analysis, the Castlegate Subdivision does not have a significant effect on the 100-year floodplain water surface elevations or the floodplain limits. The regional detention facility should adequately control the peak post- development runoff so that it will not have any impact on the properties downstream of the Crowley Tract. The increased runoff to the south into the Greens Prairie Road right-of-way has been reduced by the proposed detention facility, and there should be no flood damage to downstream or adjacent landowners resulting from this development. APPENDIX A Time of Concentration Equations & Calculations ') Time of Concentration Calculations Refer to Exhibit A for flow path used for calculations. Pre-Development Drainage Area #101: Sheet Flow: Flow length= 300' = L Slope= 2.8% n = 0.24, dense grass P2 = 4 .5" ti = 0 .007 (0.24 * 300)0 8 (4 .5)°"5 (0.028)04 ~ ti= 0.422 hours= 25.3 minutes Shallow Concentrated Flow: Flow length , L@ Slope, Sand Velocity, V Using Figure 3-1 for unpaved surface to find V L = 415' @2.4%, V = 2.5 fps = 415 I (60*2.5) = 2.8 minutes Tc= 25.3 + 2.8 = 28.1 minutes Refer to Exhibits A & B for flow path used for calculations. Post Developme11t Drainage Area #201 & #8: Sheet Flow: Flow along Gutt er: Flow length= 110' = L Slope= 1.5% n = 0.24, dense grass P2 = 4.5" ti = 0.007 (0.24 * 110)0 · 8 (4 .5)0.5 (0 .015)04 ti = 0.243 hours = 14.6 minutes Flow length, L @ Slope , Sand Velocity , V Using Figure 3-1 for paved surface to find V L = 245'@ l .62 %, V = 2 .6 fps L = 165 '@ l.0%, V = 2.0 fps = 245/(60 *2.6) + 165 /(60 *2.0) = 2 .9 minute s T c= 14 .6 + 2.9 = 17.5 minutes ... '+--.... '+- cu 0. 0 r- VI cu VI L :::J 0 u L cu .... "' 3: 3 -2 .so .20 - .10 .06 .04 - .02 - .01 - .00 5 I 1 ' . ~ I ' I I J J J J "' ' ' ' 0 ,, ~ L'"":;1 'b .:.. ~ Q.'bj ~ I I I I ' I 2 f f I 4 Ii ' ,, I I Ii , I 6 J J ,, I J J ' I Av e r age ve l ocity , ft/sec J .· . . , , I ,, I I 10 .. . Fiic u ~ :J -1.-Averal(e velocitieo fo r cstimati n l{ t r..ivel time fo r s h allow concen t rated Oow . (210 -Vl-TR -55. Seco nd Ed ., June L98Gl I 20 •• t " APPENDIXB Storm Sewer Inlet Design Calculations 12 Castlegate Subd ivisi on Secti on 5 -Phase 2 Inlet Length Calculations Inle ts In Sump 10 year storm 100 year storm Inl et# Inlet# 5.5 5-6 Flow from A c 0 10 O cwryov., Orot.,. Orot.11+10~ Y10..c1u11 L10-Req'd . Lto-actu• 0 100 (efs) (els) from Inlet I (e ls ) fcfsl (ft) (In) (Ill (ft) (efsl a.,....,_ (efsl from Inlet# L e n g th Area # (acres ) B 'J d 8.98 9.87 0 .343 4.12 12.10 -------1----1---+----i---1-----1----7 ~0 10 3 " 55 (J r:;: 0.6~ 0.')t.:.. 1.d~J "1'9 :)I l)f,!j 9.31 -1.20 !j-3, .'i-4 13.:0 1 "•') <> 5:J ~l. 2:..' 8.22 Q fJ.!j5 [· ~··: 5.51 t•j 0 .5:) ".70 4 70 ·1c:.; o.s:i :J 0 4 J .0 4 Inl ets On Grade 1 O year storm Flow from Lenglh Y10 15' 15' Area# (ft) (In) ·' .:fJ-1 ------.J [)7 -15 0 .41 0 4 .92 14 0 .382 4 .59 Transverse (Crown) slope (fUft) for Loop Street = 0.033 O pei-1001 OupKI~ O bypan (ft) (els) (e ls) (J 70 10.57 4 20 ---I- 0.7 1 1U ti:2 H0,5.~ 0.70 10 .55 -0 .77 0 .68 10 .13 -2 .01 Strai ght Crown Flow !Solved to find actual depth of flow, yl: o = o.56 • (zln ) • s "' · y'" c:i y = {0 t [0 .56 • (zln) • s "'n"' n = Roughness Coefficient= 0.0 18 S = StreeUGutter Slope (ft/ft) y = Depth of flow at inlet (ft) Cap ac ity o ( Inlets on grade: Oe = 0 .7 . [1/(H , • H2 )] • [H ,"'. H2 512] Oe = Flow capacity of inlet (cfs) H 1 =a+y H2 = a = gutter depression (2" Sta nda rd; 4" Recessed ) y = Depth of flow in approac h gutte r (ft) <lctlp1ut9d (els ) 10.57 10.07 9.78 8.12 0.68 0 .126 1.5 1 0 .83 5 38 0.273 .l28 15. 16 20 ().59 ,,, ll6 0 .400 -I.BO 12.55 12.79 5-3, 5-< P.0-1 0.332 3.f!8 11 31 15 11.07 6.06 0 .286 3A3 7.43 51 7 0.2 69 3.23 6 .3 8 10 6.36 3.3-1 0 .229 2.7• • 10 using v-• r • 0.583' a.,...,_ a.,... ... OcllPt-Cotl 010-Totlll Y100 a..,., ... (els) from Inlet# (els) (els) (els) (ft) (lnl (ft) rl .20 10.57 14 .77 o.~60 5.52 O.i5 000 5-5 0 .00 10 .07 10.07 0.•88 5 .86 0 .76 0.00 5-6 0.00 9 .78 9.78 0.460 5 .52 0.75 0 .00 8 .12 8 .12 0.428 5.13 0 .72 z = Reciprocal of crown slooo for Loop Street = 30 Inlets i n sumps. Weir Flow : L = Q I (3 • y"') c> y • (Q I 3L)'" L = Length of inlet opening (ft) Q = Flow at inlet (els) y = total depth of flow on inlet (ft) max y for inlet in sump = r = 0 .583' O rotlll Orot••10'1o Y100 (els ) (els) (ft) (In) 12.IO 1:J .. J1 0.60 8 ; 30 0 B:l 092 <; S9 7.25 0 .700 BAO 25 .3~1 27.87 11 .n? 12. rn 0.589 r or 7 43 8.17 636 6 .99 0.528 c) 33 -1 .10 4 51 100 year sto rm Ocap.:lty Q byp•• Clc..,1ured O cwryo-- (els) (els) (els) (els) from Inlet# 11 . .12 858 11 .:i2 11 .38 2.19 11.38 ~0 1 5~5 11 .30 1.89 11 .30 0 .13 5-6 10.82 0.13 10 .82 O ttyp..to1111 Clc..,1-totl 0 100-To1111 s L ilCtulll (els) (els) (els) (ftlft) (ft) 8.5El 1 1.32 1fl .fl1 0.0 280 1ii .J 2 1 11 .38 15.58 0 .0 1:'5 15 ---2.01 11 .30 13.31 0.0125 15 --- 0.13 10.82 10.95 0 .0125 15 u -~2~ Q, Q) ·- '9 g ! -s U) ~ u ~ a; -"'.r::. .!:: i5 (/) 'ji a. - 0 "' ON ...J ~ Castlegate Subdivision -Section 5, Pha s e 2 Depth of Flow in Street Gutter G utter A c Location (acres) 81 1.02 0 .55 ---------------- 82 0 .88 0.55 ----- E1 1.37 0 .55 ------ E2 0 .74 0 .55 E3 0 .62 0 .55 E4 0 .90 0 .55 F1 1.71 0 .55 F1+ F2 2 .06 0.55 Transverse (Crown ) s lope (tuft) for cul-de-sac streets = 0 .0380 for loop street = 0 .03 30 Slope (ft/ft) 0 .005 ---· 0.005 -- 0 .0100 ---- 0 .0100 0 .0100 0 .0100 0 .0125 0 .0125 10-year storm 010 Y10-aclual (cfs) (ft) (i n ) 4.84 0 .394 4.73 --------------·-- 4 .18 0 .373 4.48 ------- 6 .51 0 .367 4.40 -------- 3.51 0 .291 3.50 2.94 0 .273 3.2 7 4 .27 0 .313 3.76 8 .12 0 .382 4 .59 9.78 0.410 4 .92 ---- Stra i ght Crown Flow (Solved to find actual depth of flow in gutter, y): Q = 0 .56 * (z/n) * S 112 * y813 c> y ={QI [0 .56 * (z/n ) • S 112]}318 n =Roug hn ess Coefficient= 0 .018 S = StreeUG utter Slope (tuft) y = Depth of flow at inlet (ft) z = Reciproca l of crown slope: for cul -de-sac streets = 26 for loop street = 30 100 -year storm 0 100 Y100 (c fs) (ft) (in) 6 .53 0 .441 5.29 -------·------ 5.63 0.417 5.01 - 8 .77 0.410 4 .92 ---- 4 .74 0 .326 3.91 ----- 3 .97 0 .305 3.66 5 .76 0 .351 4 .21 ·--- -· ·-- 10.95 0.4 28 5 .13 -- 13 .19 0 .459 5.50 APPENDIXC Storm Sewer Pipe & Flume Design Calculations 15 Castlegate Subdivision Section 5 -Phase 2 Pipe Calculations Inlet Outlet 1 O year storm 100 year storm Pipe# Size Length Slope Invert Elev Invert Elev *Actual Flow Design Flow V10 Travel Time, tr1o *Actual Flow Design Flow V100 "lo Full (in) (ft) (%) (ft) (ft) (cfs) (cfs) (fps) (sec) (min) (cfs) (cfs) (fps) 5A 27 87 .2 1.10 313.88 312 .92 17.90 7 .9 55.4 11 0 .18 22 .12 8 .3 ----- 6 24 79 .0 1.39 315.23 314.13 13 .11 8.12 8.0 51.7 10 0.16 17.47 10 .82 8 .5 *The se va lues reflect the actual flow for the 18" & 24" pipes. The design flow for these pipe sizes reflects a 25% reduction in pipe area. (Refer to attached calculation for specific information.) % Full 63.6 62.0 Travel Time, h100 (sec) (min) 11 0 .18 9 0 .15 City of College Station require ment to Reduce Cross-Sectional Area of 18" & 2 4" Pipes by 25% Using Mann ings Equation from page 48 of the College Station Drainage Policy & De sign Standards Manual : Q = 1.49/n *A* R213 * S112 Q = Flow Capacity (cfs) 18" Pipe : Pipe size (inches)= 18 Wetted Perimeter W P, (ft)= 4.71 Cross-Sectional Area A , (ft2) = 1 . 766 Reduced Area A R, (ft2 ) = 1.325 Hydraulic Radius R =A/WP, (ft)= 0 .375 Reduced Hydr Radius RR= A R/W p, (ft)= 0 .281 Roughness Coeffi cie nt n = 0 .014 Friction Slope of Conduit Sr. (ft/ft) = 0 .01 Example Calculation : Slo pe Flow Capacity Reduced Flow Capacity s Q 0.005 6 .91 0 .006 7 .57 0.007 8 .18 24" Pipe: Pipe size (inches)= Wetted Perimeter WP , (ft)= Cross-Sectional Area A , (ft2 ) = Reduced Area AR, (W) = Oreduced 4.28 4.69 5.06 Hydraulic Radius R = NW P• (ft) = Reduced Hydr Radius RR = A R/W P• (ft) = Roughn ess Coefficient n = Friction Slope of Conduit Sr. (ft/ft) = Exa m p le Calculation : Slop e Fl ow Capaci ty Reduced Flow Capacity s Q Oreduced 0 .005 14 .89 9 .22 ----0 .006 16 .3 1 10 .1 -------· 0 .007 17 .6 1 10 .9 Conclusion : % Difference Ored uced /Q 0.619 0.619 0.619 24 6 .28 3 .14 2 .355 0 .5 0 .375 0 .014 0 .01 % Difference OreduceiQ 0.619 0.6 19 ------ 0.619 Mu lt iply actua l Q in 18" & 24" pipes by 1.615 to refl ec t a 25 % redu ction cross -sectional area ca lled for on pag e 4 7 , parag raph 5 of th e Co ll ege Dra in age Poli cy & Des ign Standards m a nu al. in th e Station - Castlegate Subdivision Section 5, Phase 2 -Pipe Flow Diagram 0 10 (cfs) Inlet 5-6 I 8 .12 Gutter Flow I 9.29 J, J, Pipe 6 I 8 .12 Gutter Flow I 17.24 J, J, Inlet 5-5 I 9.78 Cone . Channel I 26 .53 J, J, Pipe 5A I 17 .90 II Into Pond 26.5 II J, June Box 2 J, I Into Existi ng I 17.9 I Pipe5 0 100 (cfs) Inlet 5-6 I 10.82 Gutter Flow I 12 .56 J, J, Pipe 6 I 10 .82 Gutter Flow I 23 .24 J, J, Inlet 5-5 I 11 .30 Cone . Channel I 35 .80 J, J, Pipe 5A I 22 .12 II Into Pond I 35.8 II J, June Bo x 2 J, Into Existing I 22.1 Pipe 5 Pipe SA -10 Year Storm Manning Pipe Calculator Given Input Data: Shape .......................... . Solving for .................... . Diameter ....................... . Flowrate ....................... . Slope .......................... . Manning ' s n .................... . Computed Results: Depth .......................... . Area .......................... , . Wetted Area .................... . Wetted Perimeter ............... . Perimeter ...................... . Velocity ....................... . Hydraulic Radius ............... . Percent Full ................... . Full flow Flowrate ............. . Full flow velocity ............. . Circular Depth of Flow 27.0000 in 17 .90 00 cfs O.OllO ft/ft 0.0140 14. 9714 in 3.9761 ft2 2.2634 ft2 4S.3601 in 84 .8230 in 7 .908S fps 7.18S3 in SS .4496 % 30 .1 618 cfs 7.S8S8 fps Pipe SA -100 Year Storm Manning Pipe Calculator Given Input Data: Shape .......................... . Solving for .................... . Diameter ....................... . Flowrate ....................... . Slope .......................... . Manning ' s n .................... . Computed Results: Depth .......................... . Area ........................... . Wetted Area .................... . Wetted Perimeter ............... . Perimeter ...................... . Velocity ....................... . Hydraulic Radius ............... . Percent Full ................... . Full flow Flowrate ............. . Full flow velocity ............. . Circular Depth of Flow 27 .0000 in 22 .1200 cfs O.OllO ft/ft 0. 0140 17.1779 in 3 .9 761 ft 2 2 .669 0 ft2 49.8616 in 84 .8230 in · 8.28 77 fps 7.7081 in 63 .6220 % 30.1618 cfs 7.S8S8 fps Castlegate S ubdi v isi o n -Sec tion S, Phase 2 Col l e ge St a ti o n, Texas Pipe 6 -10 Year Storm Manning Pipe Calculator Given Input Data: Shape .......................... . Solving for .................... . Diameter ....................... . Flowrate ....................... . Slope .......................... . Manning ' s n .................... . Computed Results : Depth .......................... . Area ......................... ·.: · Wetted Area .................... . Wetted Perimeter ............... . Perimete r ...................... . Velocity ....................... . Hydraulic Radiu s ............... . Percent Ful 1 ................... . Full flow Flowrate ............. . Full flow velocity ............. . Circular Depth of Flow 24 .0000 in 13 .1100 cfs 0.0139 ft/ft 0. 0140 12 .4132 in 3 .1416 ft2 1.6396 ft2 38.5256 in 75.398 2 in 7.9956 fps 6 .1286 in 51 .7216 % 24.7663 cfs 7 .8834 fps Pipe 6 -100 Year Storm Manning Pipe Calculator Giv en Input Data: Shape .......................... . Solving for .................... . Diameter ....................... . Flowrate ....................... . Slope .......................... . Manning ' s n .................... . Computed Results : Depth .......................... . Area ........................... . We tted Area .................... . We tted Perimeter ............... . Pe rimeter ...................... . Ve loc i ty ....................... . Hy d r a ulic Radi u s ............... . Percen t Full ................... . Full f l ow Flowrate ............. . Fu ll flow ve locit y ............. . Circular Depth of Flow 24 .0000 in 17.4700 cfs 0.0139 ft/ft 0. 0140 14.87 18 in 3.1 4 16 ft 2 2 .0 4 4 8 f t 2 4 3 .4991 i n 7 5.3982 in 8 .5 435 f p s 6.7692 i n 6 1 .9660 % 2 4 .7663 cfs 7 .8834 fps Cast lega te Subdivision -Section 5, Phase 2 College Station, Texas Concrete Channel -10 Year Storm Channel Calcu lator Given Input Data: Shape .......................... . Solving for .................... . Flowrate ....................... . Slope .......................... . Re ctangular Depth of Flow 26.5000 cfs 0 .0150 ft /f t Manning's n . . . . . . . . . . . . . . . . . . . . . 0 .0140 Height . . . . . . . . . . . . . . . . . . . . . . . . . . 10.0000 in Bottom width . . . . . . . . . . . . . . . . . . . . 84 .0000 i n Computed Results: Depth .......................... ·. Velocity ....................... . Full Flowrate .................. . Flow area ...................... . Flow perimeter ................. . Hydraulic radius ............... . Top width ...................... . Area ........................... . Perimeter ...................... . Percent full ................... . 6.0402 in 7. 5211 fps 58.2411 cfs 3.5 2 34 ft2 96.0804 in 5.2 807 in 84.0000 in 5 .8333 ft2 104.0000 in 60 .4019 % Concrete Channel -100 Yea r Stor m Channel Calcu la t or Given Input Data : Shape .......................... . Solving for .................... . Flowrate ....................... . Slope .......................... . Rectangular Depth of Flow 35.8000 cfs 0.0150 ft/ft Manning's n ..................... 0.0140 Height . . . . . . . . . . . . . . . . . . . . . . . . . . 10. 0000 in Bottom width . . . . . . . . . . . . . . . . . . . . 84 .0 000 in Computed Results: Depth .......................... . Velocity ....................... . Full Flowrate .................. . Flow area ...................... . Flow perimeter ................. . Hydraulic radius ............... . Top width ...................... . Area ........................... . Peri meter ...................... . Percent full ................... . 7.3108 in 8.3946 fps 58.2411 cfs 4.2647 ft2 98 .6217 in 6.2269 i n 84 .00 00 i n 5.8333 f t2 104.0000 in 73.1085 % Castlegate S u bdi v ision -Sect i o n 5, Phase 2 College Station, Texas APPENDIXD Detention Pond Design Data & Calculations 22 Castlegate -Section 5, Phase 2 Pond Area-Capacity Data V = H * {[A1+A2 + (A1*A2)112] / 3} V =volume, ft 2 A= area , ft2 H = difference in elevation, ft Elevation Depth Area (ft) (ft) (ft') 320 .80 0 .00 0 321 .00 0 .20 380 .00 322 .00 1.20 9,815.70 323 .00 2.20 18 , 182 .30 324 .00 3.20 24,050 .10 Detention Pond Area -Capacity Data Area Volume Cumulative Volume (acres) (ft') (ft') 0 0 0 0.0087 25 .33 25 .33 0 .2253 4,042 .34 4,067 .67 0 .4174 13 ,785 .?ft 17,853.45 0 .5521 21 ,047 .93 38,901 .38 Cumulative Cumulative Volume90% Volume 90% (ft') (Ac-ft) 0 0.000 ------ 22 .80 0 .001 3,660 .90 0 .084 -16,068.11 0 .369 -35,011 .24 0.804 Castlegate Subdivision -Section 5, Phase 2 Detention Pond -Inlet Control Depth -Discharge Data Elevation Depth Flow (ft) (ft) (cfs) 320 .8 0 .0 0 .0 321 0 .2 0 .2 322 1.2 6 .5 323 2 .2 18.4 324 3 .2 28 .7 SCS CURVE NUMBER CALCULATIONS CASTLEGATE -SECTION 5, PHASE 2 PRE-DEVELOPMENT Drainage Area _ 11/(. 7 LP t Area -Ac. 6 .3 sq . mi. 0 .0098 Weighted Land Use Area, Ac . CNll CN Residential -1 /8 acre 0 .00 92 0 .0 Residential -1 /4 acre 0 .00 87 0 .0 Residential -1 /3 acre 0 .00 86 0 .0 Residential -1 /2 acre 0 .00 85 0 .0 Open Space/Grass 0 .00 80 0 .0 Pasture 5 .04 80 64 .0 Woods 1.26 79 15.8 Farm 0.00 86 0.0 Pavement 0.00 98 0.0 Water 000 100 0.0 Total-CN II 6 .30 79 .8 Average Runoff Condition CN ' 75 .6 CN I= 62 .8 ARC CN = CN I+ 0 .75(CN 11 -CN I) E 11 4-CURVE-NUM BEf~S-pre-clev xis 1 SCS CURVE NUMBER CALCULATIONS CASTLEGATE -SECTION 5, PHASE 2 POST-DEVELOPMENT Drainage Area -205 Drainage Area -206 Area -Ac. 3.7 Area -Ac. 0 .26 sq . mi. 0 .0058 sq . mi. 0.0004 Weighted Weighted Land Use Area Ac . Qi.!! CN Land Use Area, Ac. Qi.!! CN Residential -1 /8 acre 0 .00 92 0 .0 Residential -1 /8 acre 0 .00 92 0 .0 Res idential -1/4 acre 3.70 87 87 .0 Residential -1/4 acre 0 .26 87 87 .0 Residential -1/3 acre 0 .00 86 0 .0 Residentia l -113 acre 0 .00 86 0 .0 Residential -1/2 acre 0 .00 85 0 .0 Residential -1/2 acre 0 .00 85 0 .0 Open Space/Grass 0 .00 80 0 .0 Open Space/Grass 0 .00 80 0 .0 Pasture 0 .00 80 0 .0 Pasture 0 .00 80 0 .0 Woods 0.00 79 0 .0 Woods 0 .00 79 0 .0 Farm 0 .00 86 0 .0 Farm 0 .00 86 0 .0 Pavement 0 .00 98 0 .0 Pave ment 0 .00 98 0 .0 Water 0 .00 100 0 .0 Water 0 .00 100 0 .0 Total -CN II 3 .70 87 .0 Tolal -CN II 0 .26 87 .0 Average Runoff Condition CN = 83.5 Average Runoff Condition CN = 83 .5 CNI= 73 CNI= 73 ARC CN = CN I+ 0.75(CN II -CN I) ARC CN = CN I+ 0 .75(CN II -CN I) Drainage Area -207 Drainage Area -208 Area -Ac. 0 .13 Area -Ac. 2 .37 sq . mi. 0 .0002 sq . mi. 0.0037 W eighted Weighted Land Use Area , Ac. Qi.!! CN Land Use Area. Ac . CN ll CN Reside ntial -1/8 acre 0 .00 92 0 .0 Residential -1 /8 acre 0 .00 92 0 .0 Residential -1/4 acre 0 .00 87 0 .0 Residential -1 /4 acre 1.26 87 46 .3 Residential -1/3 acre 0 .00 86 0 .0 Residential -1 /3 acre 0.00 86 0 .0 Residential -1/2 acre 0 .00 85 0 .0 Residential -1 /2 acre 0 .00 85 0 .0 Open Space/Grass 0 .13 80 80 .0 Open Space/Grass 1.11 80 37 .5 Pasture 0 .00 80 0 .0 Pasture 0.00 80 0 .0 Woods 0 .00 79 0.0 Woods 0 .00 79 0 .0 Farm 0 .00 86 0 .0 Farm 0 .00 86 0 .0 Pavement 0 .00 98 0 .0 Pavement 0 .00 98 0 .0 Water 0 .00 100 0 .0 Water 0 .00 100 0 .0 Total -CN II 0 .13 80 .0 Total -CN II 2.37 83 .7 Average Runoff Condition CN = 75 .8 Average Run off Condit ion CN = 79 .5 CNI= 63 CNI= 66 .9 ARC CN = CN I+ 0 .75(CN II -CN I) ARC CN = CN I+ 0 .75(CN II -CN I) E 11 •1-CUR VE-NUMBERS-pos t-dev xis EXHIBIT A Pre-& Post-Development Drainage Area Maps 27 - Drainage Report for Castlegate Subdivision -Section 5, Phase 2 College Station , Texas June 2 0 04 Revis ed A ugust 2 004 Developer: Greens Prairie Investors, Ltd. By Greens Prairie Associates, LLC 4490 Castlegate Drive Coll ege Station, Texas 77845 (979) 69 0-7250 Pr epared B1 ': TEXCON General Contractors 1707 Graham Road Colle ge Station , Te x as 77 845 (9 79 ) 764 -77 4 3 CERTIFICATION I, Joseph P . Schultz, Licensed Professional Engineer No. 65889, State of Texas, c e rtify th a t this revised report for the drainage design for the Castlegate Subdivision -Sectiou 5, Plrase 2 , was prepared by me in accordance with the provisions of the City of College Station Drainage Policy and Design Standards for the owners hereof. ~·l-L~ Ging~o, P.E. Joseplhtl~ }4- TABLE OF CONTENTS DRAINAGE REPORT-REVISED 8120 04 CASTLEGA TE SUBDIVISION -SECTION 5, PHASE 2 CERTIFICATIO N .................................................................................................................................................................. 1 TABLE OF CONTENTS ........................................................................................................................................................ 2 LIST OF TABLES .................................................................................................................................................................. 2 INTRODUCTION ................................................................................................................................................................... 3 GENERAL LOCATION AND DESC RIPTION .................................................................................................................. 3 FLOOD HAZARD INFORMATION .................................................................................................................................... 3 DEVELOPMENT DRAINAGE PA TTERNS ....................................................................................................................... 3 DRAINAGE DESIGN CRITERIA ..................................................... .-.................................................................................. 3 STORM WATER RUNOFF DETERMINATION .............................................................................................................. .4 DETENTION FACILITY DESIGN ...................................................................................................................................... 5 STORM SEWER DESIGN .................................................................................................................................................... 7 CHANNEL DESI GN .............................................................................................................................................................. 8 CONCLUSIONS ..................................................................................................................................................................... 8 APPENDIX A .......................................................................................................................................................................... 9 Time of Co11 centration Equations & Calculations APPENDIX B ........................................................................................................................................................................ 12 Storm Sewer l11let Design Calculation s APPENDIX C ........................................................................................................................................................................ 15 Storm Sewer Pipe & Flume D esig11 Calculations APPENDIX D ........................................................................................................................................................................ 22 Detention Pond D esig n Data & Calculations APPENDIX E ........................................................................................................................................................................ 27 Detention Pond Pre-Development HEC-1 Output, Runoff Summary & Schematic APPENDIX F ......................................................................................................................................................................... 61 Detentio 11 Po11d Po st-Developm ent HEC-1 Output, Runoff Summary & Sch ematic EXHIBIT A .......................................................................................................................................................................... 202 Pre-& Post-Development Drainage A rea Maps EXHIBIT B .......................................................................................................................................................................... 204 Post-Development Drainage Area Map -Storm Sewer Desig11 LIST OF TABLES TABLE 1 -Rainfall Intensity Calculations .......................................................................................... 4 TABLE 2 -Time of Concentration (tc) Equations .............................................................................. 5 TABLE 3 -Pre-& Post-Development Runoff Information -Detention Evaluation ....................... 5 TABLE 4 -Post-D eve lopment Runoff Information -Storm Sewer Design ..................................... 5 TABLE 5 -Pre-& Post-Development Runoff Comparison -Dete ntion Pond De sig n .................... 6 TABLE 6-Summary of Maximum Pond Water Levels .................................................................... 7 DRAINAGE REPORT -REVISED 812004 CASTLEGATE SUBDIVISION -SECTION 5, PHASE 2 INTRODUCTION The purpose of this revised report is to provide th e hydrolo g ical effects of th e construction of th e Castlegate Subdivision -Sectiou 5, Phase 2 , and to veri fy th a t the propo sed stom1 dr a inage s ystem m eets the requirements set forth by the City of Coll ege Station Draina ge Policy and De sign St andards. GENERAL LOCATION AND DESCRIPTION The project is located on a portion of a 111.46 acre tract located west of State Highway 6 a long the north side of Greens Prairie Road in College Station, Texas . This report addresses Phase 2 of Section 5 of this subdivision, which is made up of 13 .51 acres . Section 5 is located adjacent to Castleg ate Section 4 along Castlegate Drive. The site is predominantly wooded. The existing ground elevations range from elevation 314 to ele vation 332 . Th e ge neral location of the project site is shown on the vicinity map in Ex hibit A. FLOOD HAZARD INFORMATION The project site is located in the Spring Creek branch of the Lick Creek Drainage Basin, with a portion in the Peach Creek Drainage Basin. Most of the proposed developed area of the site is located in a Zone X Area according to the Flood Insurance Rate Map prepared by the Federal Emergency Management Agency (FEMA) for Brazos County, Texas and incorporated areas dated February 9, 2000, panel number 48041C0205-D . This area is shown on Exhibit A as the 100-year floodplain limit. Also shown on this exhibit are the floodway limits as determined by the Castlegate Floodplain Analysis Report which was previously submitted . The Flood Hazard Area within this development has been designated as Greenway Area, which will have no development and it will be left in its current condition. DEVELOPMENT DRAINAGE PATTERNS Prior to development, the storm water runoff for Section 5, Phase 2 flows in two different directions. A majority of the runoff flows in a northwesterly direction until it enters a tributary of Spring Creek. Ultimately, this runoff flows into Spring Creek and then north to the proposed regional detention facility . Refer to the vicinity map in Exhibit A for the location of this regional detention facility .. .The remainder of the runoff from this site flows in a southerl y direction into the Greens Prairie Road right-of-way and then into a tributary of Peach Creek . DRAINAGE DESIGN CRITERIA The desi gn parameters for the storm s ewer and d ete ntion facilit y analysis a re as follo ws: • Th e Rational Method is utili z ed to de tennine p eak storm water runoff rates for th e s to m1 sewe r d esign, and the HEC-1 computer pro gram is utili ze d to determine p eak storm water runo ff rates for th e det e ntion facilit y desi gn. • Des ign Stom1 F re qu ency Storm sewe r sys tem I 0 a nd I 00-yea r s to rm eve nt s Detention facility analysis • Runoff Coefficients 5, 10 , 25, 50 and !00-year stonn eve nt s Pre-development Post-development (single family res idential) • Runoff Curve Number (CN) -Detention Pond c = 0 .30 c = 0.55 The Brazos County Soil Survey shows th e soils in th e area to be classifi ed as hydro logic group D soils . The pre-development CN is based on no development on the site. The post-development CN is based on development of Phase lofthe subdivision within the detention pond drainage area . The CN calculations are found in Appendix D. • Rainfall Intensity equations and values for Brazos County can be found in Table 1. • Time of Concentration, tc -Calculations are based on the method found in the TR-55 publication . Refer to Table 2 for the equations and Appendix A for calculations. The runoff flow paths used for calculating the pre-& post-development times of concentration for the detention pond analysis are shown on Exhibit A, and the flow path used for the post- development time of concentration for the storm sewer design is found on Exhibit B . For smaller drainage areas, a minimum tc of l 0 minutes is used to detennine the rainfall intensity values. STORM WATER RUNOFF DETERMINATION The peak runoff values were determined in accordance with the criteria presented in the previous section for the 5, l 0, 25, 50, and 100-year storm events. The drainage areas for the pre-& post-development conditions for the detention pond analysis are shown on Exhibit A. The drainage areas for the post-development conditions for the storm sewer design are shown on Exhibit B. Pre-development and post-development runoff information for the detention facility evaluation are summarized in Table 3. Post-development runoff conditions for the storm sewer design are summarized in Table 4 . TABLE 1 -Rainfall Intensity Calcu lations Rainfa ll Inte n sity Val ues (infhr) Sto rm tc = Ev ent 10 min Is 7 .693 110 8.635 hs 9.861 lso 11 .148 1100 11.639 Brazos County: 51'.'.ear storm 10 l'.'.ear storm b= 76 b= 80 d= 8.5 d= 8.5 e= 0 .785 e= 0.763 I = b I (tc+d)e I = Rainfall Intensity (infhr) tc = U(V*6 0 ) le =Time of concentratio n (min) L = Le ngth (ft) V = Velocity (ftfsec) 25 l'.'.ear storm 50 l'.'.ear storm 100 l'.'.ear storm b= 89 b= 98 b= 96 d= 8.5 d= 8.5 d= 8.0 e= 0.754 e= 0.745 e= 0 .730 (Data taken from State Department of Highways and Public Transportation Hydraulic Manual , pag e 2-16) -1 TABLE 2 -Tim e of Conce ntration (t c) Eq uation s Th e ti me of co nce nt ra ti on was de te rmin ed us in g me th ods fo und in TR -55 , "Urba n Hy drology for S ma ll Wa ters heds." The equatio ns are as f oll ows : T ime of C on ce ntration: Fo r Sheet Fl ow : Tc = T1(s hccl fl ow)+ T1(c onc cnlratcd s hecl fl ow) where : T 1 = Tra ve l T im e , m inu tes 0.007 (n L)0·8 (P z) o.s s o.4 where : T 1 = trave l tim e , ho urs n =Mannin g's rou g hn ess coe ffici e nt . L = flow length, feet P2 = 2-year, 24-hour rainfall = 4.5 " s = land slope, ft /ft F or Shallo w C oncentrated Flo w : T 1 = LI (60*V) Refer to Appendix A for calculations . where: T 1 = trave l time, m inutes V =V e locity , fp s (See F ig 3-1, App . E) L = flow length , feet TABLE 3 -Pre-& Post-Development Runoff Information -Deten tion Evaluation Area# Area CN tc l (acres) (min) (hrs) Pre 101 6.30 75 .6 28.1 0 .281 Post 205 3.70 83 .5 17 .5 0.175 Post 206 0 .26 83 .5 10.0 0 .10 Post 207 0.13 75.8 10.0 0 .10 Post 208 2 .37 79 .5 10.0 0 .10 TABLE 4 -Post-Development Runoff Information -Storm Sewer Design Area t c 5 year storm 10 year storm 25 year storm 50 year storm 100 year storm Area# c 15 Os 110 0 10 125 0 25 150 Oso 1100 0100 (acres) (min) (in/hr) (cfs) (in/hr) (cfs) (in/hr) (cfs) (in/hr) (cfs) (in/hr) (cfs) 8 1.37 0 .55 17 .5 5 .889 4 .44 6 .660 5 .02 7 .630 5 .75 8 .651 6 .52 9 .026 6 .80 9 0 .90 0 .55 10 7 .693 3 .81 8 .635 4 .27 9 .861 4 .88 11 .148 5 .52 11 .639 5 .76 10 0 .74 0 .55 10 7.693 3 .13 8 .635 3 .51 9 .861 4 .01 11.148 4 .54 11 .639 4 .74 11 0 .62 0.55 10 7 .693 2 .62 8 .635 2.94 9 .861 3 .36 11 .148 3 .80 11.639 3 .97 12 1.89 0 .55 10 7 .693 8 .00 8 .635 8 .98 9 .861 10 .25 11.148 11 .59 11 .639 12.10 14 1.71 0 .55 10 7 .693 7 .2 4 8 .635 8 .12 9 .861 9 .27 11 .148 10.48 11.639 10 .9 5 15 2 .06 0 .55 10 7 .693 8.72 8 .635 9 .78 9 .861 11 .17 11.1 48 12.63 11.639 13 .19 16 2 .12 0 .55 10 7 .693 8 .97 8 .635 10 .07 9 .861 11 .50 11 .148 13 .00 11 .639 13 .57 DETENTION FACILITY DES IGN The dete ntion facilit y ha ndlin g a po rti o n of th e runoff from this site is a regio na l fa c i l it y d e si g ne d by LJA E ng in eerin g & Surv e y in g , In c . A lso , a dete ntion po nd was co ns tru cted upstrea m of Cas tl e gate Dri ve to re du c e th e pe ak flow res ul t in g from th e Cas t legate developm e nt. Th e detention fac ilit y is located adjacent to Spring C reek prior to Spring C reek e ntering the State Highway 6 ri g ht -of-way. A detention fac ilit y is a lso needed for the runo ff that flows into the Greens Prair ie Road righ t- of-way. A comparison of th e pre-& post-d evelo pment peak discharge va lu es for Disc harge Point No. 2 shows an increase of 16 cfs in the runoff for th e 100-year stom1 event, from 28 cfs to 44 cfs. Table 5 shows th e increases in runoff for th e other s tom1 events if there was not a detention pond to contro l th e runoff. This increase in runoff is du e to the developm e nt of Phas e 2 of Section 5. Because of this increased runoff, a detention pond is proposed , which wi ll reduce the p eak runoff to less than or equal to the pre-development runoff, as the "Post-D evelopment with Pond" data in Tab le 5 shows . TABLE 5 -Pre-& Post-Development Peak Discharge Comparison -Detention Pond Design Item Location Os 010 0 2s O so 0100 (cfs) (cfs) (cfs) (cfs) (cfs) Pre-Development A Total @ Dis charge Pt. No . 2 13 16 21 25 28 Post-Development without Pond B Total @ Discharge Pt. No . 2 23 24 34 39 44 Post-Development with Pond c Into Pond 20 24 30 34 38 D Out of Pond 13 15 18 20 23 E Total@ Discharge Pt. No . 2 13 15 19 21 24 The area-capacity data and the depth-discharge data are pro vided in Appendix D. The d etention pond grading plan is shown in the construction drawings. The pond outlet structure is a concrete riser structure which is 4 'x4' in size, 2. 5' high, and with a 3 'x3' opening at its top. Th.ere is an 18 " wide op ening in th e front face of the structure with its invert at Elevation 320.5 to control the flow. The discharge pipe is a 27" reinforced concrete pipe, 62 feet in length., with. a safety end treatment at th e discharge end. Rock riprap will be placed at the discharge end to control erosion. The pipe has a d esign slope of 0. 5 %. Th e storm sewer piping for the detention facility outlet pip e will b e R CP meeting the requirements of ASTM C-76, Class Ill pipe. The top of the pond berm is at Elevation 324.0. The p eak flow out of the detention facility was determined by the HEC-1 pro g ram using the depth discharge data for the pond outl et structure as provided in App e ndix D . As shown in Tab le 5, the p eak outflow from the detention facility is less than the a llow ab le peak outflow for the d esign sto m1 event. Additionally, Tabl e 6 presents the maximum water s urface in th e pond for each stonn event , as we ll as the amo unt of freeboa rd provid ed. A sc h ematic of th e graphical HEC-1 comp ut e r m ode l, th e runoff s umm a ry , a nd the H EC-I o utput for the pre-d eve lopm e nt condition are pro v ided in Appendi x E. T he pre-d eve lopmen t flows in Table 5 a re from this HEC -1 o utput. The post-d ~ve lopment HEC-1 schematic, th e runoff summary, and the HEC-1 outp ut a re provided in Appendix F . TABLE 6 -Summary of Max imum Pond Water Levels Storm Event Water Surface Freeboard , Elevation, ft . ft . 5-year 322.45 2.1 10-year 322 .67 1.8 25-year 323 .01 1.5 50-year 323.19 1.3 100-year 323 .38 1.1 Note : Detention Pond Top of Berm Elevation= 324 .00 STORM SEWER DESIGN The storm sewer piping for this project has been selected to be Reinforced Concrete Pipe (RCP) meeting the requirements of ASTM C-76, Class III pipe meeting the requirements of ASTM C-789. The curb inlets and junction boxes will be cast-in-place concrete. Appendix B presents a summary of the storm sewer inlet design parameters and calculations . The inlets were designed based on a 10-year design storm. As per College Station guidelines, the capacities of inlets in sump were reduced by 10% to allow for clogging. Inlets for the residential streets were located to maintain a gutter flow depth of 5" or less. This design depth will prevent the spread of water from reaching the crown of the road for the 10- year storm event. Refer to Appendix B for a summary of the gutter flow depths. The runoff intercepted by the proposed storm sewer inlets was calculated using the following equations. The depth of flow in the gutter was determined by using the Straight Crown Flow equation. The flow intercepted by Inlets 5-5 & 5-6 was calculated by using the Capacity of Inlets On Grade equation. These equations and resulting data are summarized in Appendix B. There are no Inlets in Sump for this phase of construction. The area between the right-of-way and the curb line of the streets will be graded as necessary to provide a minimum of 6" of freeboard above the curb line. This will ensure that the runoff from the 1 OO~year storm event will remain within the street right-of-way. Appendix C presents a summary of the storm sewer pipe design parameters and calculations. All pipes are 18" in diameter or larger. For pip es with 18" and 24" diameters , the cross- sectional area is reduced by 25%, as per College Station requirements . A summary of ho w this was achieved is shown in Appendix C as well. The pipes for the storm sewer system were designed based on the 10-year storm eve nt, and they will also pass th e 100 -year storm eve nt. Based on the depth of flow in the street determined for the 100-year storm event, this runoff will be contained within the street right-of-way until it enters the storm sewer system . As required by College Station, the velocity of flow in the storm sewer pipe system is not lo we r than 2.5 feet per second, and it do es not exceed 15 feet per second . As th e d ata shows, eve n during lo w flow conditions, the ve lo c it y in th e pip es will exceed 2.5 feet pe r seco nd a nd prevent se diment build-up in the pipes . The maxi mum flo w in the stom1 sewer pipe system will occur in Pipe No . SA. The maximum ve lo c it y for th e pip e system in thi s deve lopm ent w ill be 8 .5 feet pe r second and will occ ur in Pipe No . 6. Appendix C contains a summa ry of the 7 pipe calculations as well as flow dia grams mappin g the flows throu gh th e sto rm sewer sys tem for the I 0 and 100-year events . CHANNEL DESIGN The storn1 runoff from the street is conveyed to the detention pond by a concrete channel. Th e channel is 7 feet wide and 10" de e p with a slope of 1.5 %. The velocity and depth for th e 10- and 100-year stonn events are 7.5 fps at 6.0" dee p and 8.4 fps at 7.3" dee p, res pectiv e ly. The velocity in the channel will be dissipated by the construction of dissip ater blo cks in th e channel after it drops into the detention pond . A 6 feet wide concrete flume is propos ed to convey the minor flows directly to the pond outlet pipe . CONCLUSIONS The construction of this project will increase the storm water runoff from this site. The proposed storm sewer system should adequately control the runoff and releas e it into existing drainages . As shown in the Castlegate Floodplain Analysis , the Castlegate Subdivision do es not have a significant effect on the l 00-year floodplain water surface elevations or the floodplain limits. The regional detention facility should adequately control the peak post- development runoff so that it will not have any impact on the properties downstream of the Crowley Tract. The increased runoff to the south into the Greens Prairie Road right-of-way has been reduced by the proposed detention facility , and there should be no flood damage to downstream or adjacent landowners resulting from this development. APPENDIX A Time of Concentration Equations & Calculations Time of Concentration Calculations Refer to Exhibit A for flow path us ed for ca lculation s. Pre-Development Drainage Area #101: Sh eet Flow: Flow length= 300' = L Slope= 2 .8% n = 0 .24, dense grass P2 = 4 .5" ti = 0 .007 (0 .24 * 300)08 (4 .5)05 (0.028)04 ~ ti = 0.422 hours= 25.3 minutes Shallow Concentrated Flow: Flow length , L@ Slope , Sand Velocity, V Using Figure 3-1 for unpaved surface to find V L = 415 ' @ 2.4%, V = 2 .5 fps = 415 I (60*2 .5) = 2.8 minutes Tc= 25.3 + 2.8 = 28.1 minutes Refer to Exhibits A & B for flow path used for calculations. Post Development Drainage Area #201 & #8: Sheet Flow: Flow along Gutter: Flow length = 110' = L Slope= 1.5% n = 0.24, dense grass P 2 = 4.5" ti= 0.007 (0.24 * 110)0 ·8 (4.5)0 5 (0.015)04 ti = 0.243 hours= 14 .6 minutes Flow length , L@ Slope, Sand Velocity, V Using Figure 3-1 for paved surface to find V L = 245'@ 1.62%, V = 2 .6 fps L = 165'@ 1.0%, V = 2.0 fps = 245 /(60*2 .6) + 165 /(60*2.0) = 2.9 minutes T c= 14.6 + 2 .9 = 17.5 minutes .... ..._ -.... ..._ cu a. 0 ..- VI cu VI ~ ::J 0 u ~ cu ..., tG 3: 3-2 .so .20 - .10 .06 .04 . 02 - .01 - .005 I 1 ) .. ' I J I I ' ' ., J 'b .. ~~ L-~, 't1 ~ 7-Q_'t1 I ~ I J I I I I 2 . ' ' ' . I 4 j ' ' ) I I I ~ I 6 I ' I ' ' . ,· I I I I , I I I 10 Average velocity. ft/sec I I . Fiicu~ :1 -1.-A•~ral(~ ·~lncili~s for C<limalinic lrnvel lime for •hallow conc~ntral~ now . (210 -Vl -TR -55 . Seco nd Ed ., June 1986) I 20 •• l APPENDIX B Storm Sewer Inlet Design Calculations 12 Castlegate Subdivis ion Section 5 -Phas e 2 In let Length Calculatio ns Inlets In Sump Inlet# Length Flow from A Area# (ac res) ~o 1.? 'l f~9 ---·---- 1 ~" ,, /J l.(M 1 9~ ~ ,:i ; f.J ------ /. 16 1fi -------uc;.:; 1 O year storm c a,. QCmT)'0\191' Orot • Orot .. •10% (els) (els) from Inlet I (els) (els) 0 .55 89d 8.98 9.87 0.5 5 0 <'2 0 .6 2 0.68 0.65 4.S~l •189 5.38 0.!'!j 9.31 4.20 5-3, [jw 4 1351 14 .116 v 5!i 8 2.! 8.22 9.04 0.55 5.5r 5.51 6.06 0.55 ..1 .70 4 70 5.1 7 --- 0 5f.i ') (J4 .1.04 3 . .14 100 year storm Y10..::1u• L1o~·c1 L10-ac1u• 0100 Orot .. Orot81 •10'l Y1 00 (ft) (In) (ft) (ft) (els) (cfsl from Inlet# (els) (els) (ft) (In) 0 .• 14:1 4.12 7.!)0 10 12.10 12.IO 1:!.31 f ).6()8 7 3 0 0.126 1.51 O.dJ 0.8:1 0 92 0.27.1 3 .28 15.16 ::o (),59 t) 59 7.25 r.7ov 8.·K 0.400 4.80 12.55 12. 79 5--3 , 5-1 25.3-1 27.87 0.332 '.J.98 11.31 15 I 1.0 7 11.07 12.18 0 5d9 7 07 0.286 3A3 7.43 't .;3 S.17 0.269 3.23 6 .38 10 6.J6 636 6.99 () 528 ti ~t.J 0 .229 2.74 ,, 10 4.10 4 51 using v-• r • 0.583' Inlets On Grade 10 year storm 100 year storm Inlet fl. 5-5 5.5 Flowlrom Length y ,. 15' 15' Area# (ft) (In) DA~ i 4 ,9-1 ----., .J U7 15 0.410 '"4.92 -14 0.382 4.59 Transverse (Crown) slope (ft/ftl for Loop Street = 0 .033 ape!' foot Oc~Kll] Q byP•• (ft) (els) (els) (J 7(1 J0.5 7 • 20 r--- 0.71 1U ,;2 .. Q.5f) 0.70 10.55 -0 .77 0.68 10.13 -2 .01 St rai ght Crown Flow (Solved to find actual depth of flow , yl : a= o.56 · (zln) • s "' • y'" Q y = {Q / [0 .56 • (zln) • s "'n'" n = Roughness Coefficient= 0 .018 S = StreeUGutter Slope (ft/ft) y = Depth of now at inlet (ft) Capacity of Inlets on grade : Oc = 0 .7 • [1/(H 1 -H2)] • [H 1 512 -H2 512] Oc = Flow capacity of inlet (cfs) H, =a+ y H2 = a = gutter depression (2" Standard; 4" Reces sed) y = Depth of now in approach gutter (ft) O upturltd (els) 10.5 i" 10.07 9.78 8.12 Ocwrr-Obyp-tot• Oc:..,1-to11 010.Totml Y100 (els) from lnl•t• (els) (els) (els) (ft) (In) •.:::o t0.5 7 14 .77 0.460 5.5:' (J()(/ 5~5 0.00 1U.07 /007 0 488 5 .86 0 .00 5-6 0 .00 9.78 9 .78 0.460 5.52 0 .00 8.12 8 .12 0.428 5.13 z = Rec iprocal of crown slope for Loop Street = 30 Inlets in sumps, Weir Flow: L = Q I (3 • y"') Q y = (Q I 3L)"' L = Length of inlet opening (ft) Q = Flow at inlet (els) y = total depth of now on inlet (ft) max y for inlet in sump = 7" = 0 .583' Op.r-1001 O ca.paclty Obyp•• Oc:..,tUl'.a O cwryo't'W O byp·IO!al O c:..,1-1011 0 100.Tot.i (ft) (els) (els) (els) (els) I from Inlet• (els) (els) (els ) (J i 5 J 1.32 858 11 J2 I fJ.50 1 l.~J2 H'.91 f---Ji8 ~~: ~.~~ -;~ ~~ ;~~~ 0 .70 t1 .JS 2.1fJ 1; .. ·w ------0.75 11 .30 1.89 11 .30 0.72 10 .82 0.13 10 .82 0.13 10.82 10 .95 s L xluJll (ft/ft) (ft) 00:28u •t: 0.01_·5 0.01 25 15 0 .012 5 15 Qi -Q) .<= .!:: u Cf)·;: a. -0 ,.._ ON ....J ~ Castlegate Subdivision -Section 5, Phase 2 Depth of Flow in Street Gutter -Revised 812004 Gutter Location 81 --- 82 - E1 .. - A (acres) 1.02 0.88 -- 1.37 -----·-- E2 0 .74 E3 0.62 c Slope (tuft) 0 .55 0 .005 ---- 0 .55 0 .005 --- 0 .55 0.0100 ------- 0 .55 0 .0100 -- 0.55 0.0100 10-year storm 010 (cfs) 4 .84 4 .18 -- 6 .51 ----- 3 .51 2 .94 Y10 -ac tu al (ft) (in) 0 .394 4.73 -· -------- 0 .373 4.48 -·------- 0.367 4.40 ----· --- 0 .291 3 .50 0 .273 3 .27 - ------ E4 0 .90 0 .55 0.0100 4.27 ci .313 3 .76 ·- ---- F1 1.71 0 .55 0.0140 8 .12 0.374 4.49 F1+ F2 2 .06 0 .55 0.0140 9 .78 0.401 4 .82 Transverse {Crown) slo12e {fUft) for cul-de-sac streets = 0 .0380 for loop street = 0.0330 Straight Crown Flow {Solved to find actual depth of flow in gutter, y): Q = 0.56 * (z/n) * S112 * ya13 ¢ y ={QI (0.56 * (z/n) * S112]}31s n =Roughness Coefficient= 0.018 S = StreeVGutter Slope (fUft) y = Depth of flow at in!et (ft) z = Reciprocal of crown slope : for cul-de-sac streets = 26 for loop street = 30 100-year storm 0 100 (cfs) 6.53 5 .63 -... 8.77 ---- 4 .74 --- 3 .97 ---- 5.76 10 .95 13 .19 Y100 (ft) (in) . 0.441 0.417 0.410 0 .326 ---·-·--- 0 .305 ----- 0 .351 . -- ----·--- 0 .419 0.449 5 .29 5 .01 4 .92 3 .9 1 - 3 .66 4 .2 1 5 .0 2 -- 5 .39 APPENDIXC Storm Sewer Pipe & Flume Design Calculations I .~