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Home My WebLink AboutDRAINAGE REPORTSaddle Creek Subdivision, Phase 4 Drainage Report ENGINEER SCHULTZ ENGINEERING, LLC. P.O. Box 11995 College Station, Texas 77842 Phone: (979) 764 -3900 Fax: (979)764 OWNER/DEVELOPER Saddle Creek Partners, Ltd. 4440 Bentwood Drive College Station, Texas 77845 Phone: (979) 690 -2642 GENERAL DESCRIPTION AND LOCATION Location: Saddle Creek Subdivision, Phase 4, is located on the south west side of FM 2154, off of Stousland Rd. Description: ■ Area: ■ Proposed Land Use: ■ # of Lots: ■ Existing Land Use: ■ Land Description: Primary Drainage Facility: Flood Hazard Information: FEMA FIRM. Floodplain: 19.804 acres Single Family Residential 14 lots Vacant The terrain slopes towards the southwest. Boggy Creek # 48041C200 -C & # 480410215 -C (July 2, 1992) Un- shaded Zone X HYDROLOGIC CHARACTERISTICS The existing site is predominately pasture land with some wooded areas. The elevations range from 287 to 272, sloping generally in a south westerly direction. The runnoff enters tributaries of Boggy Creek. GENERAL STORMWATER PLAN The drainage plan for this development will involve the construction of ditches and the installation of culverts. Page 1 of 3 DRAINAGE DESIGN General Information: Stormwater runoff from Phase 4 of the subdivision will be collected in the ditches along Prairie Dawn Trail and Lariat Lane to be discharged into an existing drainage channel. The stormwater runoff along Remington Road will be collected in the ditches and discharged to the west in the existing roadside ditch along prairie Dawn Trail in Phase 2 which flows to an existing drainage channel. T, Methodology: T, Minimum Design Storm Event: Pipe Materials: Manning's n Value: Runoff Coefficient: Design Results TR 55 10 minutes 25 -year & 100 -year - residential street & culvert, drainage channel Corrugated HDPE w /smooth interior 0.012 0.45 Culvert No. 103 Top of Road = 277.45' Q25= 15 HW 276.11' Q100= 218 HWl00= 277 Culvert No. 106 Top of Road = 285.31' Q25 = 18 . 37 HW 284.20' Q100=21.68 HW 1OO 284.61' The data presented above and in the Appendices indicates the culvert sizes are in accordance with the requirements. The head water elevation for culvert 106 is less than the top of road elevation for the 100 -yr storm runoff. The head water elevation for culvert 103 is greater than top of road elevation for the 100 year, by 0.09' (1.08 "), storm runoff, but this is a non - trapped condition. So it is in accordance with Brazos County requirements, the 25 year head water elevation is less than the top of road elevation. The velocities in the channels downstream of the culverts are low enough that grass -lined channels are appropriate. The outlet of the proposed culverts will be lined with rock riprap where erosion is likely to occur. Applicable Exhibits: DITCH DESIGN T, Methodology: T c Minimum Design Storm Event: Ditch Specifications: Manning's n Value: Runoff Coefficient. Design Results Applicable Exhibits: Exhibit A — Drainage Area Map Appendix A — Drainage Area Summary Appendix B — Pipe Design Summary & Culvert Reports TR 55 10 minutes 25 -year & 100 -year — road side ditch 4:1 Side Slope, 18" Minimum Depth 0.035 0.45 The data presented in Appendix D indicates the velocities for the road side ditch are less than the maximum Design Velocity of 4.5 ft. /sec. according to Table C -11 in the Unified Stormwater Design Guidelines. The depth of flow for each roadside ditch is less than the top of road elevation for the 100 -yr storm runoff. Exhibit B — Drainage Area Map — Ditch Design Appendix A — Drainage Area Summary - Addendum Appendix C — Ditch Design Summary Page 2 of 3 CONCLUSION The culverts and roadside ditches for this subdivision were designed in accordance with appropriate engineering standards. CERTIFICATION I, Joseph P. Schultz, Licensed Professional Engineer No. 65889, State of Texas, certify that this report for the drainage design for Saddle Creek Subdivision, Phase 4, was prepared by me in accordance with the requirements of the Brazos County Road and Bridge Department. i� Joseph P. lultz' P. E. Q - r Z Page 3 of 3 F -12327 SCHULTZ ENGINEERING, LLC. Exhibit A Drainage Area map 1 a ct 0 -- %- Lf) N 4 96z ---., CO _I M 462 —gaze; —� � � ,,� � 1 i 1 M O Z gsZ a t i vil � ti QII l �I\ iLV) ool Ow 9 4 ha N ippe O N 'o 4 a C4 x� m X W J U w Q' Q4 q w� w w y � � N cn < R i c4 L LL- Exhibit B Drainage Area Map — Ditch Design Summary N / —f- w } w LL- LLJ LO �-� a 04 W i is lO N co 496Z _Z 7 �- I f r � c IV r Z 8fit - - - I a CA la D \ `62 _ -4 -- , ( / LL X, - a. [Jjl i / ro ` NaN i t d' ry rn N lZq w II N J U co W W� �w r� A V �A A w w W No � � N w N � N o I W A$ m N I ! ICI It I \.. o LL- Appendix A Drainage Area Summary - Addendum Saddle Creek Subdivision - Phase 4 Appendix A Drainage Area Summary - Addendum Area 301 (HEC -HMS) Areas 302 -305 (Rational Method) Area # Area, A CN t lag 0 25 0 100 Area # 1 100 (in /hr) 0 100 (cfs) 301 A 5.940 0.45 20.0 7.119 (acres) 8.430 (min) (min) (hrs) (cfs) (cfs) 301 65.520 82 88.0 52.8 0.88 159.04 218.10 Areas 302 -305 (Rational Method) Area # Area, A (acres) C tc (min) 25 year storm 100 year storm 1 25 (in /hr) 0 25 (cfs) 1 100 (in /hr) 0 100 (cfs) 301 A 5.940 0.45 20.0 7.119 19.03 8.430 22.53 301 C 17.380 0.45 43.0 4.557 35.64 5.442 42.56 302 4.140 0.45 10.0 9.861 18.37 11.639 21.68 302A 0.990 0.45 10.0 9.861 4.39 11.639 5.19 302B 3.150 0.45 10.0 9.861 13.98 11.639 16.50 303A 0.860 0.45 10.0 9.861 3.82 11.639 4.50 3038 0.410 0.45 10.0 9.861 1.82 11.639 2.15 305 1 0.180 1 0.45 1 29.7 5.708 0.46 1 6.785 1 0.55 The Rational Method: 0 = CIA Q = Flow (cfs) A = Area (acres) C = Runoff Coeff. I = Rainfall Intensity (in /hr) Brazos County: I = b / (t +d)* t = U(V *60) t = Time of concentration (min) L = Length (ft V = Velocity (ft/sec) 25 year storm b = 89 d = 8.5 e = 0.754 100 year storm b = 96 d = 8.0 e = 0.730 Appendix B Pipe Design Summary & Culvert Reports Saddle Creek Subdivision - Phase 4 Appendix B Pipe Design Summary Pie Pipe No. Pipe Size (in) Length g ft Sloe p % Contributing Drainage g Areas Q se cfs xs (fps) a 100 cfs) V100 (f s 103 3-36 80 0.30 301 159.04 7.95 218.10 10.29 W 24 66 0.80 302 18.37 7.04 21.68 7.04 Culvert Report Hydraflow Express Extension for AutoCADO Civil 3D® 2013 by Autodesk, Inc. Friday, Jun 8 2012 PIPES 103 25 YR STORM Invert Elev Dn (ft) = 272.02 Calculations Pipe Length (ft) = 80.00 Qmin (cfs) = 159.04 Slope ( %) = 0.30 Qmax (cfs) = 218.10 Invert Elev Up (ft) = 272.26 Tailwater Elev (ft) _ (dc +D) /2 Rise (in) = 36.0 Shape = Circular Highlighted Span (in) = 36.0 Qtotal (cfs) = 159.04 No. Barrels = 3 Qpipe (cfs) = 159.04 n -Value = 0.012 Qovertop (cfs) = 0.00 Culvert Type = Circular Concrete Veloc Dn (ft/s) = 7.95 Culvert Entrance = Groove end projecting (C) Veloc Up (ft/s) = 7.56 Coeff. K,M,c,Y,k = 0.0045, 2, 0.0317, 0.69, 0.2 HGL Dn (ft) = 274.70 HGL Up (ft) = 275.18 Embankment Hw Elev (ft) = 276.11 Top Elevation (ft) = 277.45 Hw /D (ft) = 1.28 Top Width (ft) = 24.00 Flow Regime = Inlet Control Crest Width (ft) = 57.00 Elea (ft) 278.00 277.00 276.00 275.00 274.00 273.00 272.00 271.00 0 CircW ar Culvert HGL PIPES 10325 YR STORM Embank H%v Depth {ft} 5.74 ........_. 4.74 t of 3.74 2.74 1.74 0.74 -026 ........ -1.26 120 Reach (ft) Culvert Report Hydraflow Express Extension for AutoCADO Civil 3D® 2013 by Autodesk, Inc. Friday, Jun 8 2012 PIPES 103 100 YR STORM Invert Elev Dn (ft) = 272.02 Calculations Pipe Length (ft) = 80.00 Qmin (cfs) = 159.04 Slope ( %) = 0.30 Qmax (cfs) = 218.10 Invert Elev Up (ft) = 272.26 Tailwater Elev (ft) _ (dc +D) /2 Rise (in) = 36.0 Shape = Circular Highlighted Span (in) = 36.0 Qtotal (cfs) = 218.10 No. Barrels = 3 Qpipe (cfs) = 213.61 n -Value = 0.012 Qovertop (cfs) = 4.49 Culvert Type = Circular Concrete Veloc Dn (ft/s) = 10.29 Culvert Entrance = Groove end projecting (C) Veloc Up (ft/s) = 10.07 Coeff. K,M,c,Y,k = 0.0045, 2, 0.0317, 0.69, 0.2 HGL Dn (ft) = 274.86 HGL Up (ft) = 275.65 Embankment Hw Elev (ft) = 277.54 Top Elevation (ft) = 277.45 Hw /D (ft) = 1.76 Top Width (ft) = 24.00 Flow Regime = Inlet Control Crest Width (ft) = 57.00 Culvert Report Hydraflow Express Extension for AutoCAD® Civil 3D® 2012 by Autodesk, Inc. Friday, May 4 2012 PIPES 106 25 YR STORM Invert Elev Dn (ft) = 281.20 Calculations Pipe Length (ft) = 66.00 Qmin (cfs) = 18.37 Slope ( %) = 0.80 Qmax (cfs) = 21.68 Invert Elev Up (ft) = 281.73 Tailwater Elev (ft) = (dc +D) /2 Rise (in) = 24.0 Shape = Cir Highlighted Span (in) = 24.0 Qtotal (cfs) = 18.37 No. Barrels = 1 Qpipe (cfs) = 18.37 n -Value = 0.012 Qovertop (cfs) = 0.00 Inlet Edge = Projecting Veloc Dn (ft/s) = 6.24 Coeff. K,M,c,Y,k = 0.0045, 2, 0.0317, 0.69, 0.5 Veloc Up (ft/s) = 7.04 HGL Dn (ft) = 282.97 Embankment HGL Up (ft) = 283.28 Top Elevation (ft) = 285.31 Hw Elev (ft) = 284.20 Top Width (ft) = 24.00 Hw /D (ft) = 1.24 Crest Width (ft) = 24.00 Flow Regime = Inlet Control El" (ft) 286".00 265.00 U4.OD 283.0 282.00 281.00 284.00 PIPE S 106 25 YR STORM Hw Depth (ft) 4.27 3.27 2.27 1.27 027 -0.73 -1.73 Reach (ft) Gir Culvert HGL Embank Culvert Report Hydraflow Express Extension for AutoCAD® Civil 3D® 2012 by Autodesk, Inc. Monday, May 7 2012 PIPES 106 100 YR STORM Invert Elev Dn (ft) = 281.20 Calculations Pipe Length (ft) = 66.00 Qmin (cfs) = 18.37 Slope ( %) = 0.80 Qmax (cfs) = 21.68 Invert Elev Up (ft) = 281.73 Tailwater Elev (ft) _ (dc +D) /2 Rise (in) = 24.0 Shape = Cir Highlighted Span (in) = 24.0 Qtotal (cfs) = 21.68 No. Barrels = 1 Qpipe (cfs) = 21.68 n -Value = 0.012 Qovertop (cfs) = 0.00 Inlet Edge = Projecting Veloc Dn (ft/s) = 7.18 Coeff. K,M,c,Y,k = 0.0045, 2, 0.0317, 0.69, 0.5 Veloc Up (ft/s) = 7.72 HGL Dn (ft) = 283.04 Embankment HGL Up (ft) = 283.40 Top Elevation (ft) = 285.31 Hw Elev (ft) = 284.61 Top Width (ft) = 24.00 Hw /D (ft) = 1.44 Crest Width (ft) = 24.00 Flow Regime = Inlet Control FJ ev (ft) 286.04 285.00 284.00 HIM 282.04 281.66 286.04 PIPES 102 25 YR STORM Hw Depth (1t) 4.2 3.27 2.27 1.27 0.27 -6.73 -1.73 Reach (ft) Cir Culvert HGL Embank Appendix C Ditch Design Summary le d N ea t a 0 . 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