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Home My WebLink AboutDrainage AddendumJanuary 11, 2010 Ms. Jennifer Prochazka City of College Station Planning Services 1101 Texas Avenue College Station, TX 77842 Re: Storm Water Drainage Study - Addendum College Station ISD Transportation Center College Station, Texas Gessner Engineering Job No.: 09-0317 Dear Ms. Prochazka: This letter serves as an addendum to the drainage report that conveys the results of the storm water drainage study conducted by Gessner Engineering for the proposed College Station ISD Transportation Center in College Station, Texas. Based on the results of the Traffic Impact Analysis, the City of College Station requested that the drive onto Rock Prairie Road be moved south of the originally proposed location. This move shifted the drainage areas as shown in the attached revised Proposed Drainage Area Map (sheet C4.1). However, the amount of impervious area did not increase significantly and will not have an impact on the results of the previously submitted Storm Water Drainage Study Report. Sincerely, GESSNER ENGINEERING ��'TE'�*1, '�� G[v� ME SSA ... THOMAS Melissa P. Thomas, P.E. �j o. 98398 :. x4lydli � Morgan S. Lund, P.E. IRS 11111111112 0 6 EE I m w HIM 3 p: $ 5g gggqq 55LL a 's J�. �?�3-�xix> e r :a 8 q.p , k$ 7 v m M 0. y Qm O K z Z — DZL ". m ti ?�a CO 6n Ln �ONJ � 3> w p a m A� tt F is <1 j g 'c m mCO,STRICT _$_ eg�A1 SOY O z 8• December 7, 2009 Mr. Stephen Maldonado Jr. City of College Station Water Services Department 1101 Texas Avenue College Station, TX 77842 Re: Fire Flow Report Proposed College Station ISD Transportation Center Rock Prairie and William D. Fitch College Station, Texas Gessner Engineering Job No.: 09-0317 Dear Mr. Maldonado: The fire flow test information was provided by the City of College Station to Gessner Engineering in regards to the fire hydrant located at 7804 Rock Prairie Road, and the fire hydrant located at William D. Fitch Parkway. The fire flow information is as follows: 7804 Rock Prairie William D, Fitch Static Pressure 110 psi 116 psi Residual Pressure 110 psi 112 psi Flow 1635 gpm 1680 gpm According to the International Fire Code, the fire flow demand at this site is 2,500 gallons per minute with a flow duration of two (2) hours. This demand was determined for a Type IIA building with less than 33,200 square feet of fire flow calculation area. All proposed buildings will have sprinkler systems built in. According to an email by Ms. Carol Cotter, College Station City Engineer, structures including sprinkler systems allow for a 50% reduction of required fire demand. This reduces the total fire demand to 1,250 gallons per minute for the site. The standard formula given in AWWA M-17 (1989), shown on the next page, was utilized for converting test flow data to distribution capacity at the minimum 20 psi residual pressure. 0,54 Ps — Pr P, where, Qr = fire flow at residual pressure Pr (gpm) Ql = hydrant discharge during test (gpm) Pa = static pressure (psi) Pr = desired residual pressure (psi) Pt = residual pressure during test (psi) CV Gessner Engineering 2501 Ashford Drive Suite 102 College Station, Texas 77840 P.O. Box 10763, 77842 979.680.8840 fax 979.680.8841 2204 S. Chappell Hill Street Brenham, Texas 77833 979.836.6855 £ax 979.836.6847 The flow available with a 20 psi residual and 1 psi assumed drop in pressure at 7804 Rock Prairie Road (planned area of connection) is calculated to be greater than 18,000 gallons per minute from the hydrant test data provided. Therefore, the proposed site should have adequate fire flow for both the currently planned and future development. Fire hydrant supply pipes were sized using the water distribution modeling software, EPANET, developed by the EPA's Water Supply and Water Resources Division. The modeled system head loss was computed using the Hazen - Williams based hydraulic analysis. Please see the attached calculations from EPANET for pipe and node details. Please contact us if you have any questions or if we can be of further assistance. Sincerely, GESSNER ENGINEERING, LLP F-7451 OF TF'k1jo�� Melissa P. Thomas, P.E. ° . F. iH6mks 98 393 Kyle tZapalac, M.E., E.I.T ®BBBBOQo�FiPi?�cq��?- ko GessnerEngineering October 2, 2009 Mr. Stephen Maldonado Jr. City of College Station Water Services Department 1101 Texas Avenue College Station, TX 77842 Re: Wastewater Design Report Proposed College Station ISD Transportation Center Rock Prairie and William D. Fitch College Station, Texas Gessner Engineering Job No.: 09-0317 Dear Mr. Maldonado: The peak wastewater flow was calculated in accordance with the fixture count determination method. A total fixture unit count of 118 was determined for this building. This calculation was determined based on the fixture unit load factor given in Table I of the Sanitary Sewer Chapter of the Bryan/College Station Unified Design Guidelines. The values are shown below in Table One. Fixture Number Load TotalFactor Value Kitchen Sink 2 1 2 Lavatory 9 2 18 Shower Group 2 3 6 Urinals 3 4 12 Water Closets, Valve O erated 10 8 80 Total 118 Table One: Fixture Units The peak wastewater flow based on the fixture units is 125 gallons per minute for less than 500 fixture units. Using the Manning equation with an n value of 0.010, the velocity in all sections of the proposed sewer line were calculated as shown in Table Two below. Pipe Section PiperSize PipeaSlope Pipe Velocity (ftls) BLDG - MH1 6 2.06 5.35 MH1 - MH2 6 0.80 3.33 MH2 - MH3 6 0.80 3.33 MH3 - MH4 8 0.40 2.85 MH4 - EXIST MH 8 0.45 3.03 Table Two: Pipe Size, Slope and Velocity C7 Gessn .r Engineering 1712 South,,., pk„y Suite 105 College Station, lexa 77&10 CO. B. 10763, 77842-0763 979.680.3840 FAX979.680.SS41 2204 S. Chappol Hill Sr. Brenham, Tc. 77833 979.836.6855 FAX 979.836.6847 All pipe slopes are within the required range of minimum/maximum pipe slopes for sanitary sewer from the Bryan/College Station Unified Design Guidelines. Please contact us if you have any questions or if we can be of further assistance. Sincerely, GESSNER ENGINEERING, LLP F-7451 :5n6OFT Melissa P. Thomas, P.E. <' MEtISSA e...:............ Kyl M. apa ac, M.E., E.I.T. °t. ° ' "91 0 Gessner Engineering Page 1 12/7/2009 3:13:54 PM * E P A N E T ` Hydraulic and Water Quality * Analysis for Pipe Networks * Version 2.0 Input File: 09-0317.net Link - Node Table: --------------------------------------- Link Start End ID Node Node ------------------- P1 N1 P2 N2 P3 N3 24 N4 PS N5 P6 N6 P7 N7 28 HYD3 P9 N8 P10 N8 P11 N9 P12 N4 P13 N3 ExistingMain Nl Node Results: Node Demand ID GPM -------------------------- N1 0.00 N2 0.00 N3 0.00 N4 0.00 N5 0.00 N6 0.00 N7 0.00 HYD3 1250.00 N9 0.00 N8 0.00 BLDG_FIRE 500.00 BLDG_DOM 125.00 HYD2 0.00 HYD1 0.00 ExistingMain -1875.00 N2 N3 N4 N5 N6 N7 HYD3 N8 BLDG_FIRE N9 BLDG DOM HYD2 HYD1 ExistingMain Length Diameter ft in 134.01 12 551.14 12 171.98 12 109.30 12 305.41 12 72.53 12 119.11 8 125.12 6 35.25 6 5.32 4 42.23 4 52.00 8 136.44 8 30.66 12 ---------------------------------------- Head Pressure Quality ---------------------------------------- ft psi 249.81 108.24 0.00 248.72 107.77 0.00 244.25 105.83 0.00 242.85 105.23 0.00 241.96 104.84 0.00 239.48 103.77 0.00 238.89 103.51 0.00 231.92 100.49 0.00 227.99 98.79 0.00 228.04 98.81 0.00 227.48 98.57 0.00 227.62 98.63 0.00 242.85 105.23 0.00 244.25 105.83 0.00 250.00 0.00 0.00 Reservoir Page 2 Link Results: Link Flow VelocityUnit Headloss Status ID -------------------------------------------------------------- GPM fps ft/Kft P1 1875.00 5.32 8.12 Open P2 1875.00 5.32 8.12 Open P3 1875.00 5.32 8.12 Open P4 1875.00 5.32 8.12 Open P5 1875.00 5.32 8.12 Open P6 1875.00 5.32 8.12 Open P7 1875.00 11.97 58.51 Open P8 625.00 7.09 31.06 Open P9 500.00 5.67 15.76 Open P10 125.00 3.19 8.72 Open P11 125.00 3.19 8.72 Open P12 0.00 0.00 0.00 Open P13 0.00 0.00 0.00 Open ExistingMain -1875.00 5.32 6.23 Open Pressure 20.00 60.00 80 00 100 00 Psi Velocity 4.00 8.00 12.00 16.00 fps P2 HY03