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Home My WebLink AboutDrainage Report.. ~ ... Dramage Report for Williams Creek Subdivision -Phase 3 College Station, Texas October 2005 Developer: Joe and Janet Johnson Land and Investments, LP 1400 South Commercjal Street Coleman, Texas 76834 (325) 625-2124 Prepared By: TEXCON General Contractors 1 707 Graham Road College Station, Texas 77845 (979) 764-7743 CERTIFICATION I certify that this report for the drainage design for the Williams Creek Subdivision -Phase 3, was prepared by me in accordance with the provisions of the City of College Station Drainage Policy and Design Standards for the owners hereof, with the exception that storm water runoff detention is not being proposed for this project since the runoff will discharge directly into the l 00-year floodplain of Carters Creek. TABLE OF CONTENTS DRAINAGE REPORT WILLIAMS CREEK SUBDIVISION -PHASE 3 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 STORM CULVERT & DRAINAGE CHANNEL DESIGN ................................................................................................ 5 CONCLUSIONS ..................................................................................................................................................................... 7 APPENDIX A .......................................................................................................................................................................... 8 Time of Concentration Equations & Calculations APPENDIX B ........................................................................................................................................................................ 19 Storm Sewer Culvert Data & Design Calculations APPENDIX C ........................................................................................................................................................................ 27 Drainage Channel Design Data & Calculations APPENDIX D ........................................................................................................................................................................ 35 Drainage Ditch Data & Lining Material EXHIBIT A ............................................................................................................................................................................ 40 Drainage Area Map -Post-Development, Culverts & Channels EXHIBIT B ............................................................................................................................................................................ 42 Drainage Area Map -Post-Development, Ditch Velocities LIST OF TABLES TABLE 1 -Rainfall Intensity Calculations .............................................................................................. 4 TABLE 2 -Time of Concentration (tc) Equations .................................................................................. 4 TABLE 3 -Post-Development Runoff Information ................................................................................ 5 TABLE 4 -Area Inlet Equations & Data ................................................................................................. 6 2 DRAINAGE REPORT WILLIAMS CREEK SUBDIVISION -PHASE 3 INTRODUCTION The purpose of this report is to provide the hydrological effects of the construction of the Williams Creek Subdivision -Phase 3, and to verify that the proposed storm drainage system meets the requirements set forth by the City of College Station Drainage Policy and Design Standards. GENERAL LOCATION AND DESCRIPTION The project is located on a portion of a 213.91 acre tract located east of Rock Prairie Road and south of Greens Prairie Road in College Station, Texas. This report addresses Phase 3 of this subdivision, which is made up of 56.69 acres. The site is predominantly wooded. The existing ground elevations range from Elevation 200 to Elevation 284. Portions of the existing ground are steep, with slopes approaching 25%. 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 Carters Creek Drainage Basin. Approximately 43.5 acres of this phase of the subdivision is located in the 100-year floodplain. The remainder of this phase of the proposed subdivision 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, Community No. 481195 and 480083, Panel No. 205D, Map No . 48041 C0205D, effective dated February 9, 2000. No development is proposed for the portion of this development in the l 00-year floodplain. This area is shown on Exhibit A as the l 00- year floodplain. Lots which contain floodplain area are required to have a minimum finished floor elevation (FF), which is a minimum of one foot above the Base Flood Elevation (BFE). The BFE information is also shown on Exhibit A. DEVELOPMENT DRAINAGE PATTERNS Prior to development, the storm water runoff for Phase 3 flows in a north or easterly direction into the Carters Creek floodplain or into existing tributaries which discharge into Carters Creek. DRAINAGE DESIGN CRITERIA The design parameters for the storm drainage analysis are as follows : • The Rational Method is utilized to determine peak storm water runoff rates for the stonn drainage design for culverts, ditches and channels. • Design Stonn Frequency Stom1 cu lverts & channels Roadside ditches • Runoff Coeffici ents 25-and I 00-year stom1 events I 0-and 100-year stom1 events Post-development (I acre minimum lot size) c = 0.50 • Rainfall Intensity equations and values for Brazos Co unty can be round in Tabl e I. • 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 path us ed for calculating the post-development times of concentration for the larger drainage areas are shown on the exhibits. Smaller drainage areas use a minimum tc of 10 minutes to determine the rainfall intensity values. Exhibit A has the runoff flow paths used for the drainage areas for the culvert and channel design. Exhibit B has th e runoff flow paths used for the drainage areas for the roadside ditch design. STORM WATER RUNOFF DETERMINATION The peak runoff values were detem1ined in accordance with the criteria presented in th e previous section for the 10, 25 , 50, and 100-year storm events. The drainage areas for the post- development condition are shown on Exhibit A. Post-development runoff conditions for the storm culvert design drainage areas are summarized in Tables 3. TABLE 1 -Rainfall Intensity Calculations Rainfall Intensity Values (in/hr) Storm Event 110 hs '100 le= 10 min 8.635 9.861 11 .639 I = b I (tc+d)e I = Rainfall Intensity (in/hr) tc = L/(V*60) t.: =Time of concentration (min) L = Length (ft) V = Velocity (ft/sec) Brazos County: 10 '{_ear storm 25 '{_ear storm 50 '{_ear storm 100 '{_ear storm b= 80 b= 89 b= 98 b = 96 d= 8.5 d= 8.5 d= 8.5 d= 8.0 e= 0.763 e= 0.754 e= 0.745 e = 0.730 (Data taken from State Department of Hiqhwa'{_s and Public Transportation H'{_draulic Manual, page 2-1 6) TABLE 2 -Time of Concentration (tc) Equations The time of concentration was determined using methods found in TR-55, "Urban Hydrology for Small Watersheds." The equations are as f ollows: Time of Concentration: Tc = T1(shret flow)+ T1(co11cenlra1ed sheet flow) where: T1 =Travel Time, minutes For Sheet Flow: 0.007 (n L)°-8 (P2)0.s so.4 where: T1 =travel time, hours For S hallow Concentrated Flow: Refer to A ppendix A for calculati ons. -I n =Manning's roughness coefficient L = flow length, feet P2 = 2-year, 24-hour rainfall = 4 .5" s = land slope, ft/ft T1 = L I (60*V) where: T1 =trave l ti me, minutes V =Velocity, fps (See Fig 3-1, App /\) L = fl ow length, fee l TABLE 3 -Post-Development Runoff Information Area c le 10-year storm Culvert/ Channel No. Culvert 1 Channel4 Inlet 1; Culvert 2; Culvert 4 Channel 5 Inlet 2; Culvert 3A; Culvert 5 Culvert 38; Channel 6 Inlet 3 The Rational Method: Q=CIA Q = Flow (cfs) A= Area (acres) C = Runoff Coeff. Area # 301 301+301A 302 302+302A 303 303+303A 303A I = Rainfall Intensity (in/hr) Brazos County: 10 year storm b = 80 d = 8.5 e = 0.763 A 125 (acres) (min) (in/hr) 17.47 0.50 31 .3 4.813 18.80 0.50 31.6 4.785 6.19 0.50 35.8 4.435 7.01 0.50 36.1 4.412 5.34 0.50 31 .2 4.822 6.36 0.50 31 .7 4.776 1.02 0.50 10.0 8.635 I = b I (tc+d)e tc = Time of concentration (min) 25 year storm b = 89 d = 8.5 e = 0.754 100 year storm b = 96 d = 8.0 e = 0.730 STORM CULVERT & DRAINAGE CHANNEL DESIGN 0 25 (cfs) 42.04 44.98 13.73 15.46 12.87 15.19 4.40 25-year storm 125 0 25 (in/hr) (cfs) 5.534 48.34 5.503 51 .73 5.105 15.80 5.079 17.80 5.545 14.81 5.493 17.47 9.861 5.03 tc = L/(V*60) L = Length (ft 100-year storm 1100 0100 (in/hr) (cfs) 6.582 57.49 6.546 61.53 6.081 18.82 6.051 21.21 6.594 17.61 6.534 20.78 11 .639 5.94 V =Velocity (fl/sec) The storm culverts for this project have 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. There will be sloped safety end treatments at the end of each culvert. Runoff from the proposed streets will be collected by the roadside ditches and conveyed to the culvert structures or area inlet structures. Due to the steep side slope of the ditches on the right side of Johnson Creek Loop, inl ets will be used for this development in some locations. The inlets will allow the ditches to be less deep at the culvert locations, thereby reducing th e amount of disturbance due to the construction of the street ditch side slopes. The drainage areas for the culvert and channel designs are shown ori Exhibit A. The in lets for the right side ditch will be placed at the low point of the ditch to collect the storm water. This stom1 water will then be conveyed parallel to the roadway in a culvert where it discharges into a junction box and then into another culvert to be conveyed to th e drainage channels. The elevation of the top of the junction boxes will match the ditch tlowline, and the junction boxes will have a grate top instead of a ring-and-cover. This will allow some of the storm water to enter the pipes at this point as it flows towards the inl ets located in the low point of the ditch . The inlets located in th e low points are co nservatively designed assuming the junction box/inlets on grade do not coll ect the runoff. The proposed grate inlets were analyzed using th e ori fi cc equation, solving for th e depth of water on th e inl et for the I 0-and I 00-year storm events. It was assumed that 75% 01· th e open area of the grate would be clogged for the inl et design. Design calculations and data for the grate inl et are shown in Table 4. TABLE 4 -Area Inlet Equations & Data Q = 4.82 * ~ * y 112 ~ y =(QI (4.82 * ~))2 Where: Q = flow at inlet, cfs Ag = open area of 1-3'x3' grate, ft2 = 7 .8 ft2 y = depth at inlet, ft Actual Design Ag Inlet Ag 75% Inlet No. Size clogging 0 10 (ft2) (ft2) (cfs) 1 2-3'x3' grates 15.6 3.9 13.73 2 2-3'x3' grates 15.6 3.9 12.87 3 1-3'x3' grate 7.8 2.0 4.40 10-Year Storm 100-Year Storm Depth, y 0100 Depth, y (ft) (in) (cfs) (ft) 0.53 6.4 18.82 1.00 0.47 5.6 17.61 0.88 0.22 2.6 5.94 0.40 As shown by these calculations, the maximum depth of water for the l 00-year storm for the proposed grate inlets is 12" at Inlet No. 1. The ditch between the right-of-way and the edge of pavement is a minimum of 18" in depth, and wi ll be graded as necessary to ensure that the runoff from the l 00-year storm event will remain within the street right-of-way. Appendix B presents a summary of the storm culvert design parameters and calculations. All pipes are 18" in diameter or larger. The culverts were designed based on the 25-year storm event, and data is also given for the 100-year storm event. As shown in the summary, all of the culverts have a headwater elevation that is at least one foot below the roadway elevation for the 25-year storm event. Also, all of the culverts pass the 100-year storm event without overtopping the roadway. As required by College Station, the velocity of flow in the pipes is not lower than 2.5 feet per second, and it does not exceed 15 feet per second. As the data shows, even during lo w flow conditions, the velocity in the pipes will exceed 2.5 feet per second and prevent sediment build-up in the culverts. The maximum flow in the storm cul verts will occur in Culvert No. 1. The maximum velocity for the culverts in this development will be 8.5 feet per second and will occur in Culvert No. l. Appendix B contains a sum mary of the culvert calculator data for the 25-and 100-year storm events. Concrete riprap w ill be placed at the end of the culverts to direct the water to the drainage channels. The storm water runoff in the roadside ditches of Johnson Creek Loop wil l di scharge into three different improved drainage channels which will convey the water from the street ri ght-of-way to the flo odplain or an existing drainage whi ch ultimately flows into Carters Creek. Two of the channels (Channel Nos. 4 & 5) will be lined with concrete in the bottom to control possible erosion from the hi gh velociti es. The velocities in the concrete lined channels are 5.8 fps and 5.4 fps for Chann el No. 4 & No. 5, respectively, at the discharge of th e channels. The third chann el, Channel No. 6, is a grass lined channel. Rock riprap will be placed at th e end of each channel to disperse th e energy of the storm water and control erosion. Appendi x C cont ains a s ummary o f the channel design parameters and calculations for th e 25-and 100-year storm events. (1 (in) 12.0 10.5 4.8 The velocity of the flow in the roadside ditches was evaluated for the 10-year and 100-year storm events. The drainage areas are shown on Exhibit B. The city requirements for ditch lining material are as follows: Maximum Design Velocities of Various Surface Treatments' Surface Treatment Exposed Earth* Grass -Seeded Grass -Sodded Impermeable (Concrete, Gunite, Etc .) *Temporary Channels Only Maximum Design Velocity, (ft/sec) 3.0 4.5 6.0 10.0 'From "Erosion and Sediment Control Guidelines for Developing Areas in Texas" by the Soil Conservation Service In Appendix D the ditch velocities are summarized including comments stating the ditch lining material used. The ditch lining material is also shown in the construction drawings. CONCLUSIONS The construction of this project will increase the storm water runoff from this site. However, the runoff will be carried through a drainage system to the Carters Creek 100-year floodplain or into an existing drainage and then into the 100-year floodplain. Due to the location of this project and its proximity to Carters Creek's confluence with the Navasota River, the peak runoff from this development will occur much sooner than the peak runoff in Carters Creek, therefore, the increase in runoff has no affect on the water surface elevation in Carters Creek. The increased flow directly into Carters Creek will not have a significant impact on the surrounding property. No flood damage to downstream or adjacent landowners is expected as a result of this development. 7 APPENDIX A Time of Concentration Equations & Calculations Tc Calculations Drainage Area #301 Sheet Flow: n= 0.4 (woods -light underbrush) P= ' . 4.5; . " L= 200 Elev1= . · 280 Elev2= 270 Slope= 0.050 T,= 0.007{L *n)08 0.364 hours= 21 .8 min (P)os*(S)0.4 Concentrated Flow 1: V= . 4.2 fps (unpaved) L= 355 Elev1= 270 Elev2= ·245.9 Slope= 0.068 T,= U(60*V) = 1.4 min Ditch Flow 1 : V= 2.3 fps Q= 3 cfs L= 25 Elev1= 24p.9 Elev2= 245.5 Slope= 0.016 T,= U(60*V) 0.2 min Ditch Flow 2: V= 2 fps Q= 8 cfs L= 600 Elev1= 245.5 Elev2= 241.9 Slope= 0.006 T,= U(60*V) = 5.0 min Ditch Flow 3: V= Q= L= Elev1= 241.9 Elev2= 237.5 Slope= 0.022 T,= U(60*V) = 0.9 min Ditch Flow 4: V= 4.5 fps Q= 18 cfs L= 250 Elev1= 237.5 Elev2= 230 Slope= 0.030 T,= U(60*V) = 0.9 min Ditch Flow 5: V= 3.3 fps Q= 22 cfs L= 224 Elev1= 230 Elev2= 228.2 Slope= 0.008 T,= U(60*V) 1.1 min I Tc= 31 .3 min Concentrated Pipe Flow 1: V= 3.69 fps L= 60 Elev1= Elev2= Slope= 0.010 T,= L/(60*V) 0.3 min ITc= 31 .6 min Drainage Area #302 Sheet Flow: n= 0.4 (woods -light underbrush) P= 4.5 L= 156 Elev,= 283.8 Elev2= 282 Slope= 0.012 T,= 0.007{L *n}08 0.537 hours= 32.2 min (P)°s*(S)oA Concentrated Flow 1: V= 6.8 fps (unpaved) L= 31 1 Elev,= 282 Elev2= 232 Slope= 0.162 T1= L/(60*V) 0.8 min Concentrated Ditch Flow 1 : V= 2.3 fps Q= 4 cfs L= 203 Elev1= 232 Elev2= 229.3 Slope= 0.013 T1= L/(60*V) = 1.5 min Concentrated Ditch Flow 2: V= 1.9 fps Q= 6 L= 100 Elev1= 229.3 Elev2= 228.7 Slope= 0.006 T1= L/(60*V) = 0.9 min Concentrated Ditch Flow 3: V= 2.6 fps Q= 8 L= 65 Elev,= 228.7 Elev2= 228 Slope= 0.012 T1= L/(60*V) 0.4 min ITc= 35.8 min Concentrated Pipe Flow 1: V= 6.9 fps Q= 12 L= 75 Elev,= 228 Elev2= 220.5 Slope= 0.010 T1= L/(60*V) = 0.2 min Concentrated Pipe Flow 2: V= 6.9 fps Q= 12 L= 59 Elev1= 220.5 Elev2= 214.6 Slope= 0.010 T1= L/(60*V) 0.1 min I' c-:Jll.1 mm Drainage Area #303 Sheet Flow: n= 0.24 (dense grass) P= 4.5 L= 257 Elev1= 284.3 Elev2= 280 Slope= 0.017 Ti= 0.007(l *n}°8 = 0.458 hours= 27.5 min (P)os*(S)oA Concentrated Flow 1 : V= 2.4 fps (unpaved) L= 73 Elev1= 280 Elev2= 278.3 Slope= 0.023 Ti= L/(60*V) = 0.5 min Concentrated Ditch Flow 1 : V= 2.3 fps Q= 2 L= 100 Elev1= 278.3 Elev2= 276.1 Slope= 0.022 Ti= L/(60*V) 0.7 min Concentrated Ditch Flow 2: V= 3.4 fps Q= 3 L= 100 Elev1= 276.1 Elev2= 271.55 Slope= 0.046 Ti= L/(60*V) 0.5 min Concentrated Ditch Flow 3: V= 3.9 fps Q= 4 L= 200 Elev1= 271.55 Elev2= 260.48 Slope= 0.055 Ti= L/(60*V) 0.9 min Concentrated Ditch Flow 4: V= 4.7 fps Q= 6 L= 195 Elev1= 260.48 Elev2= 246.83 Slope= 0.070 Ti= L/(60*V) 0.7 min Concentrated Ditch Flow 5: V= 4.2 fps Q= 8 L= 100 Elev1= 246.83 Elev2= 242.49 Slope= 0.043 Ti= L/(60*V) 0.4 min Concentrated Ditch Flow 6: V= 3.1 fps Q= 10 L= 100 Elev1= 242.49 Elev2= 240.93 Slope= 0.016 Ti= L/(60'V) 0.5 min I Tc= 31 .2 min Concentrated PiQe Flow 1: V= 6.9 fps O= 12 L= 117 Slope= 0.01'0 U(60*V) = 0.3 min Concentrated Pipe Flow 2: V= 6.9 fps Q= 12 L= 86 Slope= 0.010 U(60*V) = 0.2 min 31.7 min Drainage Area #401 Sheet Flow: n= 0.4 (woods -light underbrush) P= 4.5 L= 110 Elev1= Elev2= Slope= 0.021 T1= 0.007(l *n)08 = 0 .319 hours= 19.1 min (P)os*(S)04 Concentrated Flow 1: V= 6 fps (unpaved) L= 359 Elev1= Elev2= Slope= 0.139 T1= L/(60*V) = 1.0 min Ditch Flow 1: V= 1.7 fps Q= 4 cfs L= 137 Elev1= Elev2= Slope= 0.006 T1= L/(60*V) = 1.3 min ITc= 21.4 min Drainage Area #401 & #401 A Concentrated Flow 1: V= 2.5 fps L= 140 Elev1= Elev2= Slope= 0.016 T1= L/(60*V) = 0.9 min ITc= 22.3 min Drainage Area #404 Sheet Flow: n= 0.4 (woods) P= 4.5 L= 156 Elev1= 283.8 Elev2= 282 Slope= 0.012 T1= 0.007(L*n)08 = 0.537 hours= 32.2 min (P)os*(S)04 Concentrated Flow 1: V= 6.8 fps (unpaved) L= 311 Elev,= Elev2= Slope= 0.161 T1= L/(60*V) = 0.8 min Concentrated Ditch Flow V= 1.9 fps (unpaved) Q= 2 cfs .L L= 203 Elev1= Elev2= Slope= 0.013 T1= L/(60*V) = 1.8 min ITc= 34.8 min Drainage Area #404 & #405 Concentrated Ditch Flow V= 1.7 fps (unpaved) Q= 4 cfs .L L= 100 Elev1= Elev2= Slope= 0.006 T1= L/(60*V) = 1.0 min ITc= 35.8 min Drainage Area #404, #405, & #407 A Concentrated Ditch Flow V= 2.4 fps (unpaved) Q= 6 cfs 1 : L= 65 Elev1= · Elev2= Slope= 0.012 T1= L/(60*V) = 0.5 min ITc= 36.3 min Drainage Area #410 Sheet Flow: n= 0.4 (woods -light underbrush) P= 4.5 L= 188 Elev1= Elev2= Slope= 0.123 T1= 0.007(L *n}08 = 0.242 hours= 14.5 min (P)o s*(S )04 Ditch Flow 1: V= 2.4 fps Q= 2 cfs L= 100 Elev1= Elev2= Slope= 0.023 T1= L/(60*V) = 0.7 min Ditch Flow 2: V= 3 fps Q= 2 cfs L= 216 Elev1= Elev2= Slope= 0.045 T1= L/(60*V) = 1.2 min ITc= 16.4 min Drainage Area #410 & #407 Concentrated Ditch Flow V= 2.6 fps Q= 3 cfs 1 : L= 11 5 Elev1= Elev2= Slope= 0.022 T1= L/(60*V) = 0.7 min Concentrated Ditch Flow V= 2.6 fps Q= 4 cfs 2: L= 35 Elev,= Elev2= Slope= 0.01 8 T1= L/(60*V) = 0.2 min Concentrated Ditch Flow V= 2.6 fps Q= 4 cfs 3: L= 48 Elev1= Elev2= Slope= 0 .019 T1= L/(60*V) = 0.3 min ITc= 17.6 min Drainage Area #411 Sheet Flow: n= 0.4 (woods -light underbrush) P= 4.5 L= 193 Elev1= Elev2= Slope= 0.120 T1= 0.007(L *nf8 = 0.249 hours= 14.9 min (P)os*(S)o4 Ditch Flow 1: V= 1.7 fps Q= 2 cfs L= 72 Elev1= Elev2= Slope= 0.010 T1= L/(60*V) = 0.7 min Ditch Flow 2: V= 1 .4 fps Q= 2 cfs L= 38 Elev1= Elev2= Slope= 0.006 Ti= L/(60*V) = 0.5 min ITc= 16.1 min Drainage Area #424 Sheet Flow: n= 0.24 (woods -light underbrush) P= 4.5 L= 257 Elev,= Elev2= Slope= 0.017 T1= 0.007(l *n}08 = 0.459 hours= 27.5 min (P)os*(S)04 Concentrated Flow: V= 2.4 fps (unpaved) L= 73 Elev1= Elev2= Slope= 0.023 T1= L/(60*V) = 0.5 min ITc= 28.0 min Drainage Area #424 & #421 Concentrated Ditch Flow V= 2.3 fps (unpaved) Q= 2 1 : L= 100 Elev1= Elev2= Slope= 0.223 T1= L/(60*V) = 0.7 min ITc= 28.7 min Drainage Area #424, #421 ,& #420 Concentrated Ditch Flow V= 3.9 fps (unpaved) Q= 4 .L L= 100 Elev1= Elev2= Slope= 0.045 Ti= L/(60*V) = 0.4 min ITc= 29.1 min Drainage Area #424, #421, #420,& #417 Concentrated Ditch Flow V= 3.9 fps Q= 4 1 L= 200 Elev1= Elev2= Slope= 0.055 T,= L/(60*V) = 0.9 min ITc= 30.0 min Drainage Area #424, #421 , #420, #417,& #416 Concentrated Ditch Flow V= 4.7 fps (unpaved) Q= 6 ~ L= 195 Elev1= Elev2= Slope= 0.070 T,= L/(60*V) = 0.7 min ITc= 30.7 min Dra inage Area #424, #421 , #420, #417, #416,& #414 Concentrated Ditch Flow V= 4.2 fps Q= 8 ~ L= 100 Elev1= Elev2= Slope= 0.043 T,= L/(60*V) = 0.4 min ITc= 31 .1 min Drainage Area #424, #421 , #420, #417, #416, #414, & #412 Concentrated Ditch Flow V= 3.1 fps Q= 10 1 : L= 100 Elev1= Elev2= Slope= 0.020 T,= L/(60*V) = 0.5 min !Tc= 31 .6 min ..... ..... -..... ..... v a. 0 .,, v .,, L. ::s 0 u L. qJ .... .., 3: 3-2 . 50 - .20 - .10 .06 .04 - .02 - .01 - .005 I 1 j , I ,, ' I I J ' ' ' ' ., J ' . ' b :..q,[o' 'b q, ~~ Q.,;1 I I 7 ' I 2 ~ ~ f I 4 f I) ' ,, i ) I I 6 I , I ' ; I Average velocity, ft/sec ~ I I 10 ,. , , ' I I I : I Fil(U"' .1-L-Avual(<: vdociti.,. for c•limalinr: lrnvd lim" for •hallow conc.,ntrat<:d now. (210-VI.T R·55. Second Ed .. June 198Gl I 20 APPENDIXB Storm Sewer Culvert Data & Design Calculations Williams Creek Subdivision -Phase 3 Culvert Summary Size length Slope Inlet Invert Culvert #of Elev No. Barrels (in) (ft) (%) (ft) 1 2 30 60.0 1.00 226.60 ----- 2 1 24 59.0 1.00 222.08 --· ---- 3A 1 24 61 .7 1.00 236.40 -·---· ------·-· 38 1 24 30.0 1.00 235.68 ---· - 4 1 24 64.0 1.19 222.94 ------· -- 5 1 24 116.3 1.01 237.67 Outlet Top of Road 25-year storm 100-year storm Invert Elev Design Flow V2s HW Design Flow V100 HW (ft) (ft) (cfs) (fps) (ft) (cfs) (fps) (ft) 226.00 230.56 48.34 8.2 229.1 57.49 8.5 229.4 --- 221.49 228.19 15.80 7.3 224.3 18.82 7.6 224.6 ----- 235.78 245.98 14.81 7.2 238.6 17.61 7.5 239.0 ·------------235.38 240.63 17.47 5.6 238.3 20.78 7.6 238.8 ----- 222.18 228.19 15.80 7.9 225.2 18.82 8.1 225.4 -----------236.50 242.92 14.81 7.3 239.8 17.61 7.5 240.1 Culvert 1 -25 Year Storm Culvert Calculator Entered Data: Shape ...... . Number of Barrels Solving for .................... . Chart Number ................... . Scale Number ................... . Chart Description .............. . Scale Description .............. . Flowrate ....................... . Manning's n ................ . Roadway Elevation .............. . Inlet Elevation ................ . Outlet Elevation ......... . Diameter ................. . Length ................... . Entrance Loss ............ . Tailwater ....... . Computed Results: Headwater ...................... . Slope .......................... . Velocity ....................... . Circular 2 Headwater 1 3 CONCRETE PIPE CULVERT; NO BEVELED RING ENTRANCE GROOVE END ENTRANCE, PIPE PROJECTING FROM FILL 48.3400 cfs 0 .0140 230.5600 ft 226.6000 ft 226.0000 ft 30.0000 in 60.0000 ft 0.5000 2.5000 ft 229.1144 ft From Inlet 0.0100 ft/ft 8.2199 fps Culvert 1 -100 Year Storm Culvert Calculator Entered Data: Shape .......................... . Number of Barrels . . . . . . . .... . Solving for .................... . Chart Number .................. '. . Scale Number ................... . Chart Description ........ . Scale Description ........ . Flowrate ................. . Manning's n ...... . Roadway Elevation . Inlet Elevation ... Outlet Elevation .. Diameter .............. . Length ................ . Entrance Loss ........... . Tailwater ........... . Computed Results: Headwater ........ . Slope ............ . Velocity ......... . Wil l i ams Cr eek Subdivi sio n College Station, Texas Circular 2 Headwater 1 3 CONCRETE PIPE CULVERT; NO BEVELED RING ENTRANCE GROOVE END ENTRANCE, PIPE PROJECTING FROM FILL 57.4900 cfs 0 .0140 230.5600 ft 226.6000 ft 226.0000 ft 30.0000 in 60.0000 ft 0.5000 2.5000 ft 229.4862 ft From Inlet 0.0100 ft/ft 8.5304 fps Culvert 2 -25 Year Storm Culvert Calculator Entered Data: Shape .......................... . Number of Barrels .............. . Solving for .................... . Chart Number .................. . Scale Number ................... . Chart Description .............. . Scale Description .............. . Flowrate ....................... . Manning's n .................... . Roadway Elevation .............. . Inlet Elevation ................ . Outlet Elevation ............... . Diameter ....................... . Length ......................... . Entrance Loss .................. . Tailwater ..... . Computed Results: Headwater ...................... . Slope .......................... . Velocity ....................... . Circular 1 Headwater 1 3 CONCRETE PIPE CULVERT; NO BEVELED RING ENTRANCE GROOVE END ENTRANCE, PIPE PROJECTING FROM FILL 15.8000 cfs 0.0140 228. 1900 ft 222.0800 ft 221.4900 ft 24.0000 in 59 .0000 ft 0 .5000 2.0000 ft 224.3023 ft From Inlet 0. 0100 ft/ft 7.3463 fps Culvert 2 -100 Year Storm Culvert Calculator Entered Data: Shape .......................... . Number of Barrels .............. . Solving for .................... . Chart Number ................... . Scale Number ................... . Chart Description .............. . Scale Description .............. . Flowrate ....................... . Manning 's n .................... . Roadway Elevation .............. . Inlet Elevation ................ . Outlet Elevation ............... . Diameter ....................... . Length ......................... . Entrance Loss .................. . Tailwater ...................... . Computed Results : Headwater ...... . Slope ............. . Velocity ........... . Will iams Creek Subdivision -Phase 3 CoLlege s ·at: ion, Te :.:as Circular 1 Headwater 1 3 CONCRETE PIPE CULVERT; NO BEVELED RING ENTRANCE GROOVE END ENTRANCE, PIPE PROJECTING FROM FILL 18.8200 cfs 0. 0140 228 .1900 ft 222.0800 ft 221 .4900 ft 24.0000 in 59 .0000 ft 0 .5000 2.0000 ft 224.5876 ft From Inlet 0 .0100 ft /ft 7.5672 fps Culvert 3A -25 Year Storm Culvert Calculator Entered Data : Shape ........... . Number of Barrels Solving for .................... . Chart Number ................... . Scale Number ................... . Chart Description .............. . Scale Description .............. . Overtopping .................... . Flowrate ....................... . Manning's n .................... . Roadway Elevation .............. . Inlet Elevation ................ . Outlet Elevation ....... . Diameter ....................... . Length ......................... . Entrance Loss .................. . Tailwater .... Computed Results: Headwater ...................... . Slope .......................... . Velocity ....................... . Circular 1 Headwater 1 1 CONCRETE PIPE CULVERT; NO BEVELED RING ENTRANCE SQUARE EDGE ENTRANCE WITH HEADWALL Off 14 .8100 cfs 0.0140 245.9800 ft 236.4000 ft 235 .7800 ft 24.0000 in 61.7000 ft 0.5000 2.0000 ft 238.6253 ft Inlet Control 0 .0100 ft/ft 7.2495 fps Culvert 3A -100 Year Storm Culvert Calculator Entered Data: Shape .......................... . Number of Barrels .............. . Solving for .................... . Chart Number ................... . Scale Number ................... . Chart Description .............. . Scale Description .............. . Overtopping .................... . Flowrate ....................... . Manning' s n .................... . Roadway Elevation .............. . Inlet Elevation ................ . Outlet Elevation Diameter ....... . Length ......... . Entrance Loss .................. . Tailwater ... Computed Results: Headwater .. Slope ..... . Velocity .. . VJil.Uams Creek Subdivjsi o n Co l lege S tati o n, Texas Piuse 3 Circular 1 Headwater 1 1 CONCRETE PIPE CULVERT; NO BEVELED RING ENTRANCE SQUARE EDGE ENTRANCE WITH HEADWALL Off 17.6100 cfs 0.0140 245.9800 ft 236.4000 ft 235.7800 ft 24.0000 in 61 .7000 ft 0.5000 2.0000 ft 23 8.9949 ft Inlet Control 0.0100 ft/ft 7.4932 fps Culvert 3B -25 Year Storm Cu lver t Calculator Entered Data: Shape ... .' ...................... . Number of Barrel s .............. . Solving for .................... . Chart Number ................... . Scale Number ................... . Chart Description .............. . Scale Description .............. . Overtopping .................... . Flowrate ...................... . Manning 's n ................ . Roadway Elev ation .............. . Inlet Elevation ................ . Outlet Elevation ............... . Diameter ....................... . Length ....................... . Entrance Loss ................ . Tailwater .... Computed Resu l t s : Headwater ...................... . Slope .......................... . Velocity ....................... . Circular 1 Headwater 1 1 CONCRETE PIPE CULVERT; NO BEVELED RING ENTRANCE SQUARE EDGE ENTRANCE WITH HEADWALL Off 17.4700 c fs 0.0140 240.6300 ft 235.6800 ft 235 .3800 ft 24.0000 in 30 .0000 ft 0 .5000 2.0000 ft 238.3073 ft Ou tlet Control 0 .0100 ft/ft 5 .5609 fps Culvert 3B -100 Ye a r Storm Culvert Calculator Entered Data: Shape .......................... . Number of Barrels .............. . Solving for .................... . Chart Number ................... . Scale Number ................... . Chart Description .............. . Scale Description .............. . Overtopping .................... . Flowrate ....................... . Manning 's n .................... . Roadway El e v ation .............. . Inlet Elevation ................ . Outlet Elevation ............... . Diameter ....................... . Length ......................... . Entrance Loss ........... . Tailwa ter .. Computed Results : Headwater Slope .... Velocity . \·l i l l.iarns Creek Subdiv i sion -Ph ase CollegE' S .. ~tion, J°,'";.:cis Circular 1 Headwater 1 1 CONCRETE PIPE CULVERT; NO BEVELED RING ENTRANCE SQUARE EDGE ENTRANCE WITH HEADWALL Off 20.7800 cfs 0. 0140 240.6300 ft 235.6800 ft 23 5.3800 ft 24 .0000 in 30.0000 ft 0.5000 2.0000 ft 238.7513 ft I nlet Control 0.0100 ft/ft 7.6279 fps Culvert 4 -25 Yea r Storm Culvert Calcu l ator Entered Dat a : Shape ...... . Number of Barrels .............. '. Solving for .................... 1 • Chart Number ................... . Scale Number ................... . Chart Description .............. . Scale Description .............. . Flowr ate ....................... . Manning 's n .................... . Roadway Elevation .............. . I nlet Elevati on ................ . Outlet Elevati on ............... . Di ameter ....................... . Length ......................... . Entrance Lo ss .................. . Tailwater ................... . Comput ed Results : Headwater ...................... . Slope .......................... . Velocity ....................... . Circ ular 1 Headwate r 1 3 CONCRETE PI PE CULVERT; NO BEVELED RING ENTRANCE GROOVE END ENTRANCE , PIPE PROJECTING FROM FILL 15.8000 c f s 0 . 0140 228 . 1900 ft 222.940 0 ft 222 .1800 ft 24.0000 in 64.0000 ft 0.5000 2 .5000 ft 225.1604 ft From Inlet 0.0119 ft/ft 7 .8708 f ps Culver t 4 -100 Year Storm Culver t Calcul ator Entered Data: Shape .......................... . Number of Barr els .............. . Solving for .................... . Chart Number ................... . Scale Number ................... . Chart Description .............. . Scale Descr iption .............. . Flowrate ....................... . Manning ' s n .................... . Roadwa y Elevation .............. . Inlet Elevation ................ . Outlet Elevation ............... . Diamete r ................. . Length ................. . Entrance Loss Tai l water .... Compu ted Results : Headwater ...................... . Slope .................... . Velocity ................. . Wi l l iams Creek Subdiv i s i o n -Pha se 3 Co l leqe Statio n , Texa s Circular 1 Headwater 1 3 CONCRETE PIPE CULVERT; NO BEVELED RING ENTRANCE GROOVE END ENTRANCE, PIPE PROJECTING FROM FILL 18.8200 c fs 0 .0140 228 .1900 ft 222.9400 ft 222 .1800 ft 24.0000 i n 64.0000 ft 0 .5000 2 .5000 f t 225 .4457 f t From Inlet 0.0119 ft/ft 8.1460 fps Culvert 5 -25 Year Storm Culvert Calculator Entered Data: Shape .......................... . Number of Barrels .............. . Solving for .................... . Chart Number ................... . Scale Number ................... . Chart Description .............. . Scale Description .............. . Flowrate ....................... . Manning's n .................... . Roadway Elevation .............. . Inlet Elevation ................ . Outlet Elevation ..... . Diameter ....................... . Length ......................... . Entrance Loss ...... . Tailwater .......... . Computed Results: Headwater ...................... . Slope .......................... . Velocity ....................... . Circular 1 Headwater 1 3 CONCRETE PIPE CULVERT ; NO BEVELED RING ENTRANCE GROOVE END ENTRANCE, PIPE PROJECTING FROM FILL 14.8100 cfs 0.0140 242.9200 ft 237 .6700 ft 236.5000 ft 24.0000 in 116 .3000 ft 0.5000 2.5000 ft 239.7775 ft From Inlet 0.0101 ft/ft 7.2780 fps Culvert 5 -100 Year Storm Culvert Calculator Entered Data: Shape .......................... . Number of Barrels .............. . Solving for .................... . Chart Number ................... . Scale Number ................... . Chart Description .............. . Scale Description .............. . Flowrate ....................... . Manning's n .................... . Roadway Elevation .............. . Inlet Elevation ................ . Outlet Elevation ............... . Diameter ....................... . Length ......................... . Entrance Loss .................. . Tailwater ...................... . Computed Results : Headwater . Slope ..... . Velocity .. . Williams Creek Suhd i vision -Phase 3 College Station, Texas Circular 1 Headwater 1 3 CONCRETE PIPE CULVERT; NO BEVELED RING ENTRANCE GROOVE END ENTRANCE, PIPE PROJECTING FROM FILL 17.6100 cfs 0. 0140 242.9200 ft 237.6700 ft 236.5000 ft 24.0000 in 116.3000 ft 0.5000 2.5000 ft 24 0.0521 ft From Inlet 0 .0101 ft/ft 7.5244 fps APPENDIXC Drainage Channel Design Data & Calculations 7 ' _, Williams Creek Subdivision -Phase 3 Channel Summary Bottom Side Slope 25-year storm Channel No. Width Slopes Design Flow Depth (in) (H:V) (%) (cfs) (in) 4-Segment 1 96 4:1 5.00 51.73 9.9 4-Segment 2 48 2:1 3.43 51.73 8.7 -- 4-Segment 3 48 2:1 5.95 51.73 7.5 - 5-Segment 1 24 2:1 5.00 17.80 10.9 5-Segment 2 24 2:1 7.75 17.80 5.3 6 60 4:1 1.00 17.47 9.2 100-year storm Channel V2s Design Flow Depth V100 Lining (fps) (cfs) (in) (fps) Material 5.5 61.53 10.9 5.8 Concrete --- 13.1 61.53 9.6 13.8 Concrete - 15.9 61.53 8.2 16.7 Concrete - 5.2 21 .21 11 .8 5.4 Concrete 13.9 21.21 5.9 14.6 Concrete --·- 2.8 20.78 10.0 3.0 Grass Sod Channel 4 -1 -25 Year Storm Channel Calcul ator Given Input Data : Shape .......................... . Solving for .................... . Flowrate ....................... . Slope .......................... . Manning ' s n .................... . He i ght ......................... . Bottom width ................... . Left slope ..................... . Right slope .................... . Computed Resu lts : Depth .......................... . Ve l oci ty ....................... . Full Flowrate .................. . Flow area ...................... . Flow perimeter ................. . Hydraulic radi us ............... . Top width ...................... . Area ........................... . Perimeter ...................... . Pe rcent full ................... . Trapezoidal Depth of Flow 51 .7300 cfs 0 .0050 ft/ft 0 . 0140 24 .0000 i n 96 .0000 in 0 .25 00 ft/ft (V/H) 0 .2500 ft/ft (V/H) 9.933 6 in 5.5247 fps 28 7 .0370 cfs 9.3634 ft 2 177 .914 2 i n 7.5785 i n 175 .4685 in 3 2.0000 ft 2 2 93 .9091 i n 41 .3 8 98 % Channel 4 -1 -100 Year St orm Channel Calculato r Given Input Data: Shape .......................... . Solving for .................... . Flowrate ....................... . Slope .......................... . Manning' s n .................... . Height ......................... . Bottom width ................... . Left slope ..................... . Ri ght slope .................... . Computed Results : Depth .......................... . Velo city ....................... . Flow area ...................... . Flow p erimeter ................. . Hydraulic radi us ............... . Top wid th ...................... . Area · ........................... . Perime t er ...................... . Percent f ull ................... . Wi lliams Creek Subdivi sion -Pha se 3 Col leg e Sta tion, Texas Trapezoidal Depth of Flow 6 1 .5300 cfs 0 .0050 ft /ft 0.0140 24 .0 00 0 i n 96.0000 in 0 .25 0 0 ft/ft 0 .25 00 f t/ft 10.9068 i n 5 .8 1 81 fps 1 0 .5755 ft2 185.9394 i n 8 .1902 in 183 .2 541 i n 32 .00 0 0 f t 2 2 93 .9091 i n 45 .4448 % Channel 4-2 -25 Year Storm Channel Calculator Given Input Data: Shape .......................... . Solving for .................... . Flowrate ....................... . Slope .......................... . Manning's n .................... . Height ......................... . Bottom width ................... . Left slope ..................... . Right slope .................... . Computed Results: Depth .......................... . Velocity ....................... . Full Flowrate .................. . Flow area ...................... . Flow perimeter ................. . Hydraulic radius ............... . Top width ...................... . Area ........................... . Perimeter ...................... . Percent full ................... . Trapezoidal Depth of Flow 51.7300 cfs 0.0343 ft/ft 0.0140 24.0000 in 48.0000 in 0.5000 ft/ft (V/H) 0 .5000 ft/ft (V/H) 8.6878 in 13. 1153 fps 362.2592 cfs 3.9443 ft2 86.8531 in 6.5395 in 82. 7513 in 16.0000 ft2 155 .3313 in 36.1993 % Channel 4-2 -100 Year Storm Channel Calculator Given Input Data: Shape .......................... . Solving for .................... . Flowrate ....................... . Slope .......................... . Manning's n .................... . Height .......................... . Bottom width ................... . Left slope ..................... . Right slope .................... . Computed Results: Depth .......................... . Velocity ....................... . Flow area ...................... . Flow perimeter ................. . Hydraulic radius ............... . Top width ...................... . Area ........................... . Perimeter ...................... . Percent full ................... . Wi ll iams Creek Subdivision -Phase 3 College Station , Texas Trapezoidal Depth of Flow 61 .5300 cfs 0.0343 ft/ft 0.0140 24.0000 in 48.0000 in 0.5000 ft/ft 0.5000 ft/ft 9.5571 in 13.8137 fps 4 .4543 ft2 90.7406 in 7.0687 in 86.2284 in 16.0000 ft2 155.3313 in 39.8212 % Channel 4 -3 -2 5 Year Storm Channel Calc u l ato r Given Input Data : Shape .......................... . Solving for .................... . Flowrate ....................... . Slope .......................... . Manning' s n .................... . Height ......................... . Bott om width ................... . Left slope ..................... . Right slope .................... . Computed Results : Depth .......................... . Velocity ....................... . Full Flowrate .................. . Flow area ...................... . Flow perimeter ................. . Hydraulic radi us ............... . Top width ...................... . Area ........................... . Perimeter ...................... . Percent full ................... . Trapezoidal Depth of Flow 51.7300 cfs 0 .0595 ft/ft 0 . 0140 24 .0000 in 48 .0000 i n 0 .5000 ft/ft (V/H) 0.5000 ft/ft (V/H) 7.4550 in 15.8832 fps 477 .1235 cfs 3 .2569 ft2 81.3398 i n 5.7659 in 77.8200 in 16.0000 ft2 155.3313 in 31.0625 % Channel 4-3 -100 Ye a r Stor m Channel Calculator Giv en Input Data: Shape .......................... . Sol ving for .................... . Flowrate ....................... . Slope .......................... . Manning' s n .................... . Height ......................... . Bottom width . · .................. . Left slope ..................... . Right slope .................... . Computed Results: Depth .......................... . Velocity ....................... . Flow area ...................... . Flow per ime ter ................. . Hydr aulic r adi us ............... . Top width ...................... . Area ........................... . Pe r imet er ...................... . Percent f u ll ................... . Will i ams Creek Subd ivisio n -Phase 3 Col leg e Statio n , Texa s Trapezoidal Depth of Flow 61.5300 cfs 0.0595 ft/f t 0. 0140 24.0000 in 48.0000 in 0.5000 ft/ft 0 .5000 ft/ft 8.2113 i n 16.74 94 fps 3 .6736 ft2 8 4.722 1 in 6.243 9 i n 8 0 .8453 in 16.0000 ft2 155.3313 in 34.213 8 % Channel 5 -1 -25 Year Storm Channel Calculator Giv en Input Data : Shape .......................... . Solving for .................... . Flowrate ....................... . Slope .......................... . Manning 's n .................... . Height ......................... . Bottom width ................... . Left slope ..................... . Right slope .................... . Computed Results: Depth .......................... . Velocity ....................... . Full Flowrate .................. . Flow area ...................... . Flow perimeter ................. . Hydraulic radius ............... . Top width ...................... . Area ........................... . Perimeter ...................... . Percent full ................... . Trapezoidal Depth of Flow 17.8000 cfs 0 .0050 ft/ft 0.0140 24 .0000 in 24 .0000 in 0.5000 ft/f t (V/H) 0 .5000 ft/ft (V/H) 10.8616 in 5 .1612 fps 95.7679 cfs 3.4488 ft2 72.5745 in 6 .8430 in 67 .4464 in 12.0000 ft2 1 31.3313 in 45 .2567 % Channel 5 -1 -100 Year Storm Channel Calculator Given Input Data: Shape .......................... . Solving for .................... . Flowrate ....................... . Slope .......................... . Manning's n .................... . Height ......................... . Bottom wi dth ................... . Left slope ..................... . Right slope .................... . Computed Results : Dept h .......................... . Velocity ....................... . Flow area ...................... . Flow pe r imeter ................. . Hydraulic r adi us ............... . Top width ...................... . Area ........................... . Perime t er ...................... . Percent fu ll ................... . Williams Creek Subdivision -Phase 3 College S tat i on , Te xas Trapezoidal Depth of Flow 21 .2100 cfs 0.0050 ft/ft 0.0140 24 .0000 in 24 .0000 i n 0 .5000 ft/ft 0.5000 ft/ft 11 .8441 in 5.4074 fps 3.9224 ft 2 76.9685 in 7.3384 in 71 .3765 in 12.0000 ft 2 131.3313 in 49.3505 % Channel 5-2 -25 Year Storm Channel Calculator Given Input Data : Shape .......................... . Solving for .................... . Flowrate ....................... . Slope .......................... . Manning's n .................... . Height ......................... . Bottom width ................... . Left slope ..................... . Right slope .................... . Computed Results: Depth .......................... . Velocity ....................... . Full Flowrate .................. . Flow area ...................... . Flow perimeter ................. . Hydraulic radius ............... . Top width ...................... . Area ........................... . Perimeter ...................... . Percent full ................... . Trapezoidal Depth of Flow 17.8000 cfs 0.0775 ft/ft 0. 0140 24.0000 in 24.0000 in 0 . 5000 ft/ft (V/H) 0 .5000 ft/ft (V/H) 5.3296 in 13. 8761 fps 377.0386 cfs 1.2828 ft2 47.8347 in 3.8616 in 45 .3184 in 12 .0000 ft2 131 .3313 in 22.2067 % Channel 5 -2 -100 Year Storm Channel Calculator Given Input Data: Shape .......................... . Solving for .................... . Flowrate ....................... . Slope .......................... . Manning's n .................... . Height ......................... . Bottom width ................... . Left slope ..................... . Right slope .................... . Computed Results: Depth .......................... . Velocity ....................... . Flow area ...................... . Flow perimeter ................. . Hydraulic radius ............... . Top width ...................... . Area ........................... . Perimeter ...................... . Percent full ................... . WilJ ia111s Cre ek Subdivi sion -µ11ase 3 Coll ege Sta t ion , Texas Trapezoidal Depth of Flow 21.2100 cfs 0.0775 ft/ft 0 . 0140 24.0000 in 24.0000 in 0 .5000 ft/ft 0.5000 ft/ft 5.8574 in 14.5999 fps 1 .4528 ft2 50.1951 in 4.1677 in 47.4296 in 12.0000 ft2 131.3313 in 24.4059 % Channel 6 -25 Year Storm Channel Calculator Given Input Data: Shape .......................... . Solving for .................... . Flowrate ....................... . Slope .......................... . Manning's n .................... . Height ......................... . Bottom width ................... . Left slope ..................... . Right slope .................... . Computed Results: Depth .......................... . Velocity ....................... . Flow area ...................... . Flow perimeter ................. . Hydraulic radius ............... . Top width ...................... . Area ........................... . Perimeter ...................... . Percent full ................... . Trapezoidal Depth of Flow 17.4700 cfs 0.0100 ft/ft 0.0350 24 .0000 in 60 .0000 in 0.2500 ft/ft 0.2500 ft/ft 9.1794 in 2.8336 fps 6.1654 ft2 135.6955 in 6.5427 in 133.4354 in 26.0000 ft2 257.9091 in 38.2476 % Channel 6 -100 Year Storm Channel Calculator Given Input Data: Shape .......................... . Solving for .................... . Flowrate ....................... . Slope .......................... . Manning's n .................... . Height ......................... . Bottom width ................... . Left slope ..................... . Right slope .................... . Computed Results: Depth .......................... . Velocity ....................... . Flow area ...................... . Flow perimeter ................. . Hydraulic radi us ............... . Top width ...................... . Area ........................... . Perimeter ...................... . Percent full ................... . Wil liams Creek Subcilv is ion -Phase l Co l Lege Sta t.ion , Tc~:-:as Trapezoidal Depth of Flow 20.7800 cfs 0.0100 ft/ft 0.0350 24.0000 in 60 .0000 in 0.2500 ft/ft 0 .2500 ft/ft 10 .0392 in 2.9760 fps 6 .9826 ft2 142.7855 in 7.0420 in 140.3137 in 2 6 .0000 ft2 2 57.9091 in 41.8301 % APPENDIXD Drainage Ditch Data & Lining Material Williams Creek Subdivision -Phase 3 Left Ditch Evaluation Data Area, c Area# A (acres) 402 0.28 0.50 --403 0.23 0.50 ---403,406 0.43 0.50 -409 0.29 0.50 -409,408 0.40 0.50 --- 413 0.24 0.50 ----- 423 0.23 0.50 -----423,422 0.31 0.50 ----- 423,422,419 0.39 0.50 -----423,422,419,418 1.15 0.50 ------423,422,419,418,415 1.37 0.50 The Rational Method: tc (min) 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 Q =CIA I = b I (tc+d)" 5 year storm 1 O year storm 25 year storm Is Os 110 0 10 l2s 0 2s (in/hr) (cfs) (in/hr) (cfs) (in/hr) (cfs) 7.693 1.08 8.635 1.21 9.861 1.38 7.693 0.88 8.635 0.99 9.861 1.13 7.693 1.65 8.635 1.86 9.861 2.12 7.693 1.12 8.635 1.25 9.861 1.43 7.693 1.54 8.635 1.73 9.861 1.97 7.693 0.92 8.635 1.04 9.861 1.18 7.693 0.88 8.635 0.99 9.861 1.13 7.693 1.19 8.635 1.34 9.861 1.53 7.693 1.50 8.635 1.68 9.861 1.92 7.693 4.42 8.635 4.96 9.861 5.67 7.693 5.27 8.635 5.91 9.861 6.76 0 = Flow (cfs) A= Area (acres) C = Runoff Coeff. le = Time of concentration (min) tc = L/(V*60) L = Length (ft V =Velocity (ft/sec) I = Rainfall Intensity (i n/hr) Brazos Count'i_: 5 't_ear storm 10 'i_ear storm 25 'i_ear storm b = 76 b = 80 b = 89 d = 8.5 d = 8.5 d = 8.5 e = 0.785 e = 0.763 e = 0.754 50 year storm 100 year storm 150 Oso 1100 0 100 (in/hr) (cfs) (i n/hr) (cfs) 11.148 1.56 11 .639 1.63 11 .148 1.28 11.639 1.34 11 .148 2.40 11.639 2.50 11 .148 1.62 11 .639 1.69 ------ 11 .148 2.23 11 .639 2.33 11 .148 1.34 11 .639 1.40 -- 11.148 1.28 11 .639 1.34 ·- 11 .148 1.73 11 .639 1.80 -11.148 2.17 11 .639 2.27 -11 .148 6.41 11 .639 6.69 ------·-11 .148 7.64 11 .639 7.97 50 't_ear storm 100 't_ear storm b = 98 b = 96 d = 8.5 d = 8.0 e = 0.745 e = 0 .730 Williams Creek Subdivision -Phase 3 Right Ditch Evaluation Data Area, c Area# A (acres ) 401 3.02 0.50 -------401 ,401A 4.82 0.50 ----404 1.76 0.50 -404,405 2.99 0.50 ----· 404,405,407A 3.59 0.50 410 1.35 0.50 ----------410,407 2.66 0.50 -411 0.47 0.50 -424 1.15 0.50 ----424,421 1.41 0.50 --424,421 ,420 2.11 0.50 ----424,421 ,420,417 3.14 0.50 -----424,421 ,420,417,416 3.96 0.50 ----424,421 ,420,417,416,414 4.64 0.50 424,421,420,417,416,414,412 4.86 0.50 The Rational Method: tc (min) 21 .4 22.3 34.8 35.8 36.3 16.4 17.6 16.1 28.0 28.7 29.1 30.0 30.7 31 .1 31.6 Q = CIA I = b I (tc+d)8 5 year storm 1 O year storm 25 year storm Is Os 110 0 10 l2s 0 2s (l nlhr) (cfs) (I nf hr) (cfs) (inf hr) (cfs) 5.277 7.97 5.986 9.04 6.866 10.37 5.156 12.43 5.852 14.10 6.715 16.18 3.946 3.47 4.513 3.97 5.194 4.57 ------3.876 5.79 4.435 6.63 5.105 7.63 3.842 6.90 4.397 7.89 5.062 9.09 6.093 4.11 6.883 4.65 7.882 5.32 ---------5.872 7.81 6.640 8.83 7.608 10.12 6.151 1.45 6.947 1.63 7.955 1.87 -- 4.512 2.59 5.141 2.96 5.908 3.40 4.446 3.13 5.067 3.57 5.824 4.11 4.409 4.65 5.026 5.30 5.777 6.09 4.327 6.79 4.936 7.75 5.675 8.91 ------4.267 8.45 4.869 9.64 5.598 11 .08 ------4.233 9.82 4.831 11.21 5.556 12.89 4.191 10.18 4.785 11 .63 5.503 13.37 ll = Flow (cts) tc = Time ot concentration (min) tc = L/(V*60) L = Length (tt A= Area (acres) C = Runoff Coeff. I = Rainfall Intensity (inlhr) Brazos Count'i_: 5 'i_ear storm b = 76 d = 8.5 e = 0.785 V =Velocity (ft/sec) 10 'i.ear storm 25 'i.ear storm b = 80 b = 89 d = 8.5 d = 8.5 e = 0.763 e = 0.754 50 year storm 100 year storm lso Oso 1100 0 100 (lnlhr) (cfs) (inf hr) (cfs) 7.796 11 .77 8.135 12.28 7.625 18.38 7.958 19.18 5.916 5.21 6.185 5.44 5.816 8.70 6.081 9.09 5.768 10.35 6.031 10.83 8.934 6.03 9.321 6.29 ---8.626 11.47 9.000 11 .97 9.015 2.12 9.406 2.21 6.719 3.86 7.017 4.03 6.625 4.67 6.919 4.88 6.572 6.93 6.865 7.24 6.457 10.14 6.746 10.59 6.371 12.62 6.656 13.18 6.323 14.67 6.607 15.33 6.264 15.22 6.546 15.91 50 'i.ear storm 100 'i.ear storm b = 98 b = 96 d = 8.5 d = 8.0 e = 0.745 e = 0.730 Williams Creek Subdivision -Phase 3 Johnson Creek Loop Left Ditch From To Slope Drainage Area # Station Station 13+70 16+56 0.60% 402 ------16+56 19+25 -1 .32% 403 -19+25 21+57 -0.60% 403,406 ---,_ 21+90 23+00 2.20% 409,408 ----23+00 25+25 4.45% 409 --25+25 28+60 2.28% 413 -28+60 29+40 -0.60% 413 29 +4 0 32+00 7.00% 423,422,419,418,415 32 +00 34+00 5.48% 423,422,419,418 --34+00 35+00 4.54% 423,422,419 35+00 36+00 2.23% 423,422 -36+00 37+50 0.80% 423 -37+50 38+64 0.60% 423 n = 0.035 for Grass "V" bottom ditch n = O 014 for Concrete 4H·1v Side slopes 0 10 V10 d10 0 100 V100 d100 Ditch Lining Material (els) (fps) (in) (els) (fps) (in) 1.21 1.3 5.9 1.63 1.4 6.6 Grass seeded 0.99 1.6 4.7 1.34 1.7 5.3 Grass seeded --------1.86 1.4 6.9 2.50 1.5 7.7 Grass seeded --1.73 2.2 5.3 2.33 2.4 5.9 Grass seeded 1.25 2.7 4.1 1.69 2.9 4.6 Grass seeded >-1.04 2.0 4.3 1.40 2.2 4.8 Grass seeded 1.04 1.2 5.6 1.40 1.3 6.2 Grass seeded 5.91 9.4 4.8 7.97 10.1 5.3 Concrete ---------4.96 4.1 6.6 6.69 4.4 7.4 Grass Sod ------------1.68 2.9 4.5 2.27 3.2 5.1 Grass sod --------1.34 2.1 4.8 1.80 2.3 5.3 Grass seeded ----0.99 1.3 5.2 1.34 1.4 5.8 Grass seeded ----0.99 1.2 5.5 1.34 1.3 6.1 Grass seeded Williams Creek Subdivision -Phase 3 Johnson Creek Loop Right Ditch From To Station Slope Drainage Area # Station 13+70 15+00 0.60% 401 - 15+00 16+56 1.63% 401, 401A ---16+56 19+25 -1.32% 404 19+25 20+25 -0 .60% 404,405 20+25 20+90 -1.24% 404,405,407A 21+02 21+50 1.88% 404 ,405,407A 21+50 21+85 1.79% 410,407 ----21+85 25+91 4.45% 410 --25+91 27+50 -1.00% 411 ------27+50 27+88 -1.83% 411 ·---27+88 29+00 1.34% 424,421 ,420,417,416,414 29 +00 32+00 7.00% 424 ,421,420,417,416 32+00 34+00 5.48% 424 ,421 ,420,417 34+00 35+00 4.54% 424,421 ,420 35+00 36+00 2.23% 424,421 -------·--36+00 37+50 0.80% 424 ----37+50 38+64 0.60% 424 n = 0.035 for Grass "V" bottom ditch n = 0.014 for Concrete 4H:1V Side slopes 0 10 V10 d10 0100 V100 d100 Ditch Lining Material (els) (fps) (in) (els) (fps) (in) 9.04 2.1 12.5 12.28 2.3 14.0 Grass seeded 14.10 3.4 12.2 19.1 8 3.7 13.7 Grass seeded 3.97 2.3 7.9 5.44 2.5 8.9 Grass seeded 6.63 1.9 11 .1 9.09 2.1 12.5 Grass seeded 7.89 2.6 10.4 10.83 2.9 11.7 Grass seeded 7.89 3.1 9.6 10.83 3.3 10.8 Grass seeded ----8.83 3.1 10.1 11 .97 3.4 11 .3 Grass sod 4.65 3.7 6.7 6.29 4.0 7.5 Grass sod -1.63 1.6 6.0 2.21 1.8 6.7 Grass seeded - 1.63 2.1 5.3 2.21 2.2 6.0 Grass seeded 11.21 5.9 8.3 15.33 6.4 9.3 Concrete 9.64 10.6 5.7 13.18 11.4 6.4 Concrete -7.75 4.6 7.8 10.59 5.0 8.8 Grass Sod ·-5.30 3.9 7.0 7.24 4.2 7.9 Grass sod --3.57 2.7 6.9 4.88 2.9 7.8 Grass seeded 2.96 1.8 7.8 4.03 1.9 8.7 Grass seeded 2.96 1.6 8.2 4.03 1.7 9.2 Grass seeded EXHIBIT A Drainage Area Map -Post-Development, Culverts & Channels .~() EXHIBIT B Drainage Area Map -Post-Development, Ditch Velocities 42