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Home My WebLink AboutDrainage ReportDrainage Report for Holiday Inn Development Liberty Subdivision College Station, Texas June 2004 Revised July 2004 Developer: Texas Hotel Management Corp. 1203 University Drive East College Station , Texas, 77840 Prepared By: TEXCON Genera] Contractors 1 707 Graham Road Coll ege Station, Texas 77845 (979) 764-7743 )"NA . ~-lq -Olf e ·.~pr<) ~ DV7-d-\-d\ ~l~m.2WY CERTIFICATION I, Joseph P. Schultz, Licensed Professional Engineer No. 65889, State of Texas, certify that this report for the drainage design for the Holiday Inn Development, was prepared by me in accordance with the provisions of the City of College Station Drainage Policy and Design Standards for the owners hereof. _,_,,,,, --'\~ OF r ,, r;(,,_~ ······· ~-t: '• "'<?> ••••••• •• ""i'ui •• , .. · ·. , I!•: ... * ' "*• .• ., ~ ................................... 'i.: i ... 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'\"~AL;.---... .-: -;~ ~df TABLE OF CONTENTS HOLIDAY INN DEVELOPMENT CERTIFICATION~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~l TABLEOFCONIB 2 LISTOFTABIES 2 INTRODUCTION. 3 GENERAL LOCATION AND DESCRIPTION 3 FLOOD HAZARD INFORMATION. 3 DEVEWPMENTDRAINAGEPATIERNS 3 DRAINAGE DESIGN CRITERIA 4 STORM WATER.RUNOFF DETERMINATION. 5 DETENTION FAClllIYDESIGN. 6 CONQ USIONS 7 APPENDIX A 8 Tim e of Concentration Data & Calculatio11s Storm Pipe Design Data & Calculatio11s Pond A rea-Capacity Data, Depth-Discharge Data, & Storage Routing Analysis Parameters Storage Routing Analysis -Detention Pond Table 1.2-Twin City Church of Christ Drai11age Report Hydro graphs EXFD.BITA ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~41 Pre-Development Drainag e Area Map Post-Development Drainage A rea Map Liberty Subdivision Lot 2 Gradi11g & Drai11age Plan Holiday Inn Grading & Drai11age Plan LIST OFT ABLES TABLE 1 -Pre-Development Runoff Info rmation ........................................................................... 5 TABLE 2 -Post-Development Runoff Info m1ation .......................................................................... 5 TABLE 2A -Flow from Church of Christ Detenti on Pond .............................................................. 5 TABLE 2B -Post Development Flow into Holiday Inn Detenti on Facilities .................................. 5 TABLE 3 -Detention Pond -Comparison of Pre-& Post-Development Flows ............................. 6 TABLE 4 -M aximum Water Surface Elevations & Water Depths .................................................. 7 2 DRAINAGE REPORT HOLIDAY INN DEVELOPMENT INTRODUCTION The purpose of this report is to provide the hydrological effects of the construction of the Holiday Inn Development, and to show that the storm water drainage structures and the proposed detention facility for this site will control the stonn water runoff in such a manner so as to have no offsite or downstream impact. GENERAL LOCATION AND DESCRIPTION The proposed Holiday Inn Hotel will be located on a 2.763 acre tract, Lot 1, Block 1 of the Liberty Subdivision, located south of the intersection of State Highway 6 and Southwest Parkway in College Station, Texas. The Holiday Inn project site is not adjacent to SH 6 or Southwest Parkway. Vehicular access to the site will be provided by the construction of access driveways to each roadway through Lot 2, Block 1 of the Liberty Subdivision. The existing ground elevations range from elevation 280 to elevation 285 for the Holiday Inn site, and they range from elevation 276 to elevation 287 for Lot 2. The proposed development will consist of a 5-story hotel building with parking and/or driveways on all sides of the building. Exhibit B shows the location of the proposed buildings and pavement. FLOOD HAZARD INFORMATION The project site is located in the Wolfpen Creek and Bee Creek Drainage Basins. This development is located in a Zone X Area according to the Flood Insurance Rate Map prepared by the Federal Emergency Management Agency for Brazos County, Texas and incorporated areas dated July 2, 1992, panel number 48041C0144-C. Zone X Areas are dete1mined to be outside of the 500-year floodplain. DEVELOPMENT DRAINAGE PATTERNS The storm water runoff from the site prior to this development flowed into 2 different directions. The majority of the runoff from Lot 1 flows southeast onto the adjacent property and then into an existing pond. The runoff from Lot 2 flows east and then n01ih to an existing stonn sewer inlet in the SH 6 right-of-way. This existing stom1 sewer system discharges to the north into a tributary of Lick Creek. The pre-development drainage areas are shown in Ex hibit A. The topography shown withi n the limits of the site is from field survey data. The topography shown adjacent to this prope1iy is from aerial topo graphy prepared in 1994 for the City of Co llege Station. The majority of the runoff fro m the 2 adjacent properti es to th e no1ihwest of Lot l drains onto Lot l . The McCord Engi neering Building site has a stonn sewer inl et in the rear parking lot which drains south to ward Lot 1 through a 12" diameter pip e. The Twin City Church of Christ site wi ll have a detention pond which discharges into the northwest comer of Lot 1. , -' After the proposed development, a majority of the storn1 water runoff will continue to flow in the pre-development direction. The Grading & Drainage Plan for Lot 2 of the Liberty Subdivision has been included as Exhibit C. The Grading & Drainage Plan for the Holiday Inn project has been included in this report as Exhibit D. A curb opening and flume has been added to receive the runoff from the adjacent properties and convey it to the parking lot of the Holiday Inn project. The location of these flumes is shown on Exhibit D. The amount of runoff flowing offsite will be addressed in subsequent sections of this report. The post development drainage area boundaries are shown in Exhibit B. The post- development runoff onto the adjacent property will be controlled and released at or below the pre-development peak runoff rates for the design stom1 event by detaining the runoff in the detention facility. The runoff from Lot 2 will continue to flow to the existing inlet in the SH 6 right-of-way. The design criteria and results of the proposed detention facility design are included in subsequent sections of this report. DRAINAGE DESIGN CRITERIA The design parameters for the private stom1 sewer and detention facility are as follows: • The Rational Equation is utilized to detem1ine peak storm water runoff rates for the sto1m sewer and detention facility design. Q=CIA Q =Flow (cfs) A = Area (acres) C = Runoff Coeff. I = Rainfall Intensity (in/hr) • The rainfall intensity (I) used for the peak flow calculations area was determined by the following equation: I = b I (tc+d)e tc =Time of concentration (min) Brazos County: 10 )J_ear storm 25 vear storm b = 80 b = d = 8.5 d = e = 0.763 e = • Design Storm Frequency Private Stom1 Sewer Detention Pond 89 8.5 0.754 50 vear storm I 00 )J_ear storm b = 98 b = 96 d = 8.5 d = 8.0 e = 0.745 e = 0.730 10 and 100-year storm events 10, 25 , 50 and 100-year sto1m events • The following runoff coefficients were used for this proj ect: Open Space/Grass Wooded Areas Landscape Areas Paved Areas Building Roof 0.40 0.20 0.50 0.90 0.90 The composite runoff coefficient values used in computing the peak runoff values can be found in Tables 1 & 2. • Time of Concentration, tc -Calculations fo r the pre-development and post- development conditions are based on the method found in the TR-55 publication. Refer to Appendix A for the equations and calculations. A minimum tc of 10 minutes is used to detem1ine the rainfall intensity. The drainage runoff flow path used for calculation of the pre-development and post-development time of concentrati on for the drainage areas are shown on Exhibits A & B. Pre-development runoff conditions are summarized in Table 1. Post-development runoff conditions are summarized in Table 2. The runoff from the Twin City Church of Christ property was not calculated. The peak runoff values were taken from the Drainage Report prepared in October 2003 by Ash & Browne Engineering, Inc. The peak runoff outflow values for the proposed detention pond for Twin City Church of Christ are shown in Table 2A. (Table 2.1 from the drainage report is included in Appendix E.) These values were added to the peak runoff values from Drainage Area 201 and used as the peak runoff into the proposed detention facility for the Holiday Inn. These values are shown in Table 2B. TABLE 1 -Pre-Development Runoff Information Area c 5 year storm 10 year storm 25 year storm 50 year storm Area# (acres) le 1, a, 1,. a,, 1,, a,, 1,, Q,. c, c, c, c, CTot•I 100 year storm 1100 a,,. A, I A, I A, I A. I ATot•I (min) (in/hr) (cfs) (in/hr) (els) (in/hr) (els) (in/hr) (cfs) (in/hr) (cfs) 101 0.11 I 2.35 + 0 I o.98 I 4.04 0.20 0.40 0.50 0.90 0.49 13 6.837 13.43 7.699 15.12 8.805 17.29 9.967 19.57 10.400 20.43 102 5.62 I 3.51 0 I 0 I 9.13 0.20 0.40 0.50 0.90 0.28 32.1 4.151 10.49 4.740 11.98 5.452 13.78 6.207 15.69 TABLE 2 -Post-Development Runoff Information Area c 5 year storm 10 year storm 25 year storm 50 year storm Area# (acres) le I, Q, I,. Q,. I,, Q,, 1,, Q,, c, c, c, c, C Tot•I A, A, A, A, ATol•I (min) (in/hr) (els) (in/hr) (efs) (in/hr) (efs) (in/hr) (els) 201 0 0.44 0.72 2.98 4.14 0.20 0.40 0.50 0.90 0.78 15.0 6.376 20.52 7.194 23.15 8.234 26.50 9.328 30.02 202 2.76 1.84 0 0.27 4.87 0.20 0.40 0.50 0.90 0.31 10 7.693 11.78 8.635 13.22 9.861 15.10 11 .148 17.07 203 2.04 0.40 0 0.14 2.58 0.20 0.40 0.50 0.90 0.27 ~ 4.664 3.24 5.308 3.68 6.098 4.23 6.933 4.81 204 0.24 1.22 0 0.12 1.58 0.20 0.40 0.50 0.90 0.41 25.7 4.749 3.06 5.403 3.48 6.205 4.00 7.053 4.54 203 future 2.04 0.40 0 0.14 2.58 --------0.60 27 4.612 7.14 5.251 8.13 6.033 9.34 6.860 10.62 TABLE 2A -Flow from Church of Christ Detention Pond 0 50 3.27 3.68 4.17 4.73 4.95 TABLE 2B -Post Development Flow into Holiday Inn Detention Facilities 23.79 26 .83 30.67 34.75 36.27 STORM WATER RUNOFF DETERMINATION The peak runoff valu es for the access dri veway storn1 sewer Pipe No. 1 was determined in accordance with the criteria presented in th e previo us section for the 10-and 100-year storm events. Pipe o. 1 is a 24" RCP, 48 feet in length with a slope of 0.5 %. Drainage Area 203 drains to this pipe. The pipe has been designed fo r the fu ture development of Lot 2. The peak runoff values are as lollows: 6.486 16.40 100 year storm 1100 0 100 (in/hr) (els) 9.732 31.32 11.639 17.82 7.239 5.02 7.364 4.74 7.163 11.09 Q JO = 8 .13 cfs Qi oo = 11.09 cfs The private 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 or HDPE pipe manufactured by Hancor or ADS. Appendix B presents a summary of the stonn sewer pipe design parameters and design calculations. As the data shows, the velocity in the pipe will exceed 2 feet per second and prevent sediment build-up in the pipe. The maximum velocity for Culvert o. 1 will be 3.5 feet per second. This pipe will pass both the 10-and 100-year storm events. Data for the storm sewer pipe can be found in Appendix B. Storm Pipe No. 2 will be installed and both ends plugged since this pipe will be used to convey runoff under the access driveway after development of Drainage Area 204. o design data is presented for this pipe in this report. DETENTION FACILITY DESIGN The design storm fo r the Holiday Inn detention facility is the 100-year storm event. The detention pond is located along the southeast portion of the tract, and the parking lot also functions as a detention pond. The peak runoff values were determined in accordance with the criteria presented in previous sections for the 5, 10, 25, 50 & 100-year stonn events for pre-development conditions. Table 3 shows a summary of these results. Appendix F has hydrographs for each stom1 event which shows the pre-development, post-development and detention pond outflow. The post-development peak runoff values are also summarized in Table 3. Figure 1 in Appendix C shows the required detention storage vo lume for the pond for the 100-year storm event. TABLE 3 -Detention Pond - Comparison of Pre-& Post-Develop Description 05 0 10 0 100 (2._w\~ ~-)CO~ (cfs) (cfs) (cfs) Pre-Development-DA 101 13.43 17.29 19.57 20 .43 Church of Christ Detention Pond 4.17 4.73 4.95 18.80 21.46 24.30 25.38 14.67 16.38 18.52 20.89 21.14 2.03 2.42 2.94 3.41 4.24 The area-capacity data, the depth-discharge data and the Storage Routing Analysis Parameters for the proposed detention pond is provided in Appendix C. The peak flow out of the detention faci lity was detem1ined by a Storage Routing Analysis based on the Continuity Equation as fo llows: (Jl +I2)+((2sl/dt)-01 )=((2s2/dt)+02). The time interval, dt, used was 1 minute. The calcu lations and results of the Storage Routing Analysis are provided in Appendix D. TABLE 4 -Maximum Water Surface Elevations & Water Max Water 6.0 9.0 Minimum parking lot driveway pavement elevation = 281 .30 As shown at ottom of Table 3, the peak runoff from the project site for the post- development condition is less than or equal to the pre-development peak flow for the site for each stom1 event. Table 4 shows the maximum water surface elevation and maximum depth in the parking lot for the 10-and 100-year stonn events. The maximum depth of water in the parking lot for the 100-year storm event is less than 1 O'', as required by the Drainage Policy and Design Standards. CONCLUSIONS The construction of this project will increase the storm water runoff from this site. However, the proposed detention facility will adequately control the peak post- development runoff to that of the pre-development runoff for each design storm event for Lot 1. Additional detention facilities will be required for Lot 2 at the time this property is developed. No flood damage to downstream landowners is expected as a result of the development of Lot 1 or the initial development of the access driveways for Lot 2. 7 APPENDIX A Time of Concentration Data & Calculations 8 Time of Concentration Equations The time of concentration was determined using methods found in TR-55, "Urban Hydrology for Small Watersheds. " The equations are as follows: Time of Concentration: For Sheet Flo w: Tc= Ti(shcet flow)+ T t(concentratecl sheet flow) where: T1 = Travel Time, minutes 0.007 (n L)°-8 (P2)0.s so.4 where: T1 = travel time, hours n =Manning's roughness coefficient L = flow length, feet P2 = 2-year, 24-hour rainfall = 4.5" s = land slope, ft/ft For Shallow Concentrated Flow: T, =LI (60*V) where: T1 = travel time, minutes V =Velocity, fps (See Fig 3-1 , App. E) L = flow length, feet Time of Concentration Calculations Pre-Development Drainage Area 101: Sheet Flow #1: Sheet Flow #2: Flow length = 23 ' = L Slope = 0.66% n = 0 .15, short grass prairie P2 = 4.5" ti = 0.007 (0.1 5 * 23)0 8 (4.5)05 (0.0066)04 t1 = 0.066 hours= 4.0 minutes Flow length = 29' = L Slope = 0.66% n = 0.01 1, concrete pavement P2 = 4.5" ti = 0.007 (0.011 * 29)0·8 (4.5)05 (0.0066)04 t1 = 0.0099 hours= 0 .6 minutes Shallow Concentrated Flow: 1st Segment Flow length = 302' = L Slope = 0.54% For paved surface at 0.54%, Velocity (V) = 1.5 fps (see Fig. 3-1 ) ~ t1 = 302' I ( 60* 1.5) = 3 .4 minutes Flow Through Drainage Pipe: Segment Flow length = 61 ' = L Slope = 0.84% From Culvert Calculator data, Velocity, V = 5.0 fps t1 = 61 ' I (60*5 .0) = 0.2 minutes Shallow Co ncentrated Flow: 2"d Segment Flow length = 150' = L Slope = 1.0% For paved surface atl.0%, Velocity (V) = 1.6 fps (see Fig. 3-1) t1 = 150' I (60*1.6) = 1.6 minutes Shallow Co ncentrated Flow: 3 rct Segment Flow length = 315 ' = L Slope = 1.0% For paved surface atl.0%, Velocity (V) = 1.6 fps (see Fig. 3-1 ) t1 = 315 ' I (60*1.6) = 3.3 min utes T c= 4.0 + 0.6 + 3.4 + 0.2 + 1.6 + 3.3 = 13.1 minutes Pre-Developm ent Drainage A rea I 02: Sheet Flow: Flow length = 200' = L Slope = 1.5% n = 0.24, dense grass P2 = 4.5" ti= 0.007 (0.24 * 200)08 (4.5)05 (0 .015)04 t1 = 0.392 hours= 23.5 minutes Shallow Concentrated Flow: 151 Segment Flow length = 525 ' = L Slope = 1.5% For unpaved surface at 1.5%, Velocity (V) = 2 fps (see Fig. 3-1) Similarly: 2"ct Segment L = 240' @ S = 0.38%, V = 1.05 fps 3rct Segment L = 65 '@ S = 2.46%, V = 2.46 fps ~ tt = 525 '/(60*2) + 240'/(60*1.05) + 65 '/(60*2.46) Tc= 23 .5 + 4.4 + 3.8 + 0.4 = 32.1 minutes Time of Concentration Calculations, continued Post-Development Drainage Area 201 : Sheet Flow #1: Sh eet Flow #2: Flow length = 23' = L Slope = 0.66% n = 0.15, short grass prairie P2 = 4.5" ti= 0.007 (0.15 * 23)°-8 (4.5)05 (0.0066)04 t1 = 0.066 hours= 4.0 minutes Flow length = 29 ' = L Slope = 0.66% n = 0.011 , concrete pavement P2 = 4.5" ti= 0.007 (0.0 11 * 29)0 8 (4.5)05 (0.0066)04 t1 = 0.0099 hours= 0.6 minutes Shallow Concentrated Flow: 151 Segment Flow length = 302' = L Slope = 0.54% For paved surface at 0.54%, Velocity (V) = 1.5 fps (see Fig. 3-1) t1 = 302' I (60*1.5) = 3.4 minutes Flow Through Drainage Pipe/Flume: Segment Flow length = 78 ' = L Slope = 0.84% From Culvert Calculator data, Velocity, V = 5.0 fps ~ t1 = 78 ' I (60*5.0) = 0.3 minutes Shallow Concentrated Flow: 211d Segment Flow length = 173' = L Slope = 0.65% For paved surface at 0.65%, Velocity (V) = 1.65 fps (see Fi g. 3-1) ~ t1 = 173 ' I (60* 1.65) = 1.8 minutes Similarly: 3rd Segment L = 200 '@ S = 0.83%, V = 1.85 fp s 4111 Segment L = 280'@ S = 0.54%, V = 1.5 fps ti= 200'/(60*1.85) + 280'/(60*1.5) = 4.9 Tc= 4.0 + 0.6 + 3.4 + 0.3 + 1.8 + 4.9 = 15.0 minutes Post-Development Drainage Area 202: Using Tc = 10 minutes Post-Development Drainage Area 203: Sheet Flow: Flow length= 200' = L Slope = 1.75% n = 0.24, dense grass P2 = 4.5" ti = 0.007 (0 .24 * 200)08 (4.5)0'5 (0.0175)04 t1 = 0.368 hours= 22.1 minutes Shallow Concentrated Flow: Flow length= 360' = L Slope = 0.7% For unpaved surface at 0.7%, Velocity (V) = 1.35 fps (see Fig. 3-1) ~ t1 = 360' I (60*1.35) = 4.4 minutes ~ Tc= 22.1 +4.4 = 26.5 minutes Post-Development Drainage Area 204: Sheet Flow: Flow length = 200' = L Slope = 1.5% n = 0.24, dense grass P2 = 4.5 " ti = 0.007 (0.24 * 200)°8 (4.5)05 (0.015 )04 t1 = 0.392 hours= 23 .5 minutes Shallow Concentrated Flow: 151 Segment Flow length = 85 ' = L Slope= 1% For unpaved surface at 1 %, Velocity (V) = 1.6 fps (see Fig. 3-1) t1 = 85' I (60*1.6) = 0.9 minutes 2"d Segment Flow length = 155 ' = L Slope = 1% For paved surface at 1 %, Velocity (V) = 2.0 fp s (see Fig. 3-1) t1 = 155' I (60*2.0) = 1.3 minutes Tc= 23 .5 + 0.9 + 1.3 = 25.7 minutes APPENDIXB Storm Pipe Design Data & Calculations 14 Culvert 1 -10 Year Storm Culvert Calculator Entered Data: Shape ................... . Number of Barrels ....... . Solv ing for ............. . Chart Number ............ . Scale Number ............ . Chart Description ....... . Scale Description .. . Flowrate .......... . Manning's n ....... . Roadway Elev ation . 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 8.1300 cfs 0.0140 281.2000 ft 277 .3400 ft 277 .1000 ft 24.0000 in 48.0000 ft 0.2000 2.0000 ft 279 .0564 ft From Outlet 0.0050 ft/ft 2.5879 fps Culvert 1 -100 Ye ar 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 Elev ation .. Outlet Elev ation Diameter ........ . Length . . . . . . .... . Entrance Loss .. . Tailwater .... . Computed Results: Headwater .. Slope ... Velocity ... Holiday Inn College Station, Texas Circular 1 Headwater 1 3 CONCRETE PIPE CULVERT; NO BEVELED RING ENTRANCE GROOVE END ENTRANCE, PIPE PROJECTING FROM FILL 11.0900 cfs 0.0140 281.2000 ft 277 .3400 ft 277.1000 ft 24 .0000 in 48.0000 ft 0.2000 2.0000 ft 279 .2255 ft From Outlet 0.0050 ft/ft 3 .5301 fps 17 35.00 30.00 25.00 - -IJ) ..... ~ 20.00 a 15.00 10.00 5.00 - Figure 1 Storage Volume Determination Post-Devlopme t =36.27 cfs I Storage Area=1 9,210 CF t e-Dev~lop~ent 0 10 =25.38 cfs I I f I -+----+---+-----+-+---J__ I I r I O .OO +-~~~~~~~~.____--'--~~~__,~__,_~~~--'~...,.-~~--'---'-~~-+~__._~~~~~-r--~~~~~~-1 0 500 1000 1500 2000 2500 3000 Time of Concentration (sec) Holiday Inn Pond Area-Capacity Data V = H * {[A1+A2 + (A1*A2)112] / 3} V = volume, ft2 A= area, ft2 H = difference in elevation, ft INLET NO. 1 Area -Capacity Data Elevation Depth Area Area (ft) (ft) (ft2) (acres) 279.75 0.00 0 0 280.00 0.25 465.33 0.0107 280.50 0.75 3,362.34 0.0772 281.00 1.25 6,637.82 0.1524 281 .50 1.75 11238.10 0.2580 282.00 2.25 22875.41 0.5251 282.50 2.75 33107.14 0.7600 Volume (ft3) 0 38.78 846.42 2,454.07 4,418.81 8,357.85 13,917.06 E 112-area -capacity data-0709.04 xis Cumulative 90 % Cumulative Volume Volume (ft3) (ft3) 0 0 38.78 34.90 885.20 796.68 3,339.27 3005.34 7,758.07 6982.27 16, 115.92 14504.33 30,032.98 27029.68 Holiday Inn Pond Outlet Structure Depth Discharge Data Orifice Equation: Q = 4.82 *A * y112 Weir Equation: Q = 3.0 * L * d312 Elevation (ft) 279.75 280.00 280.50 281.00 281.50 282 .00 282.50 * Weir Flow ** Orifice Flow 1 y = 0.5' 2 y = 1.0' Depth d (ft) 0 0.25 0.75 1.25 1.75 2.25 2.75 Depth -Discharge Data Q y 3.0'x0.75' opening (ft) (cfs) 0 0 0.25 1.13* 0.50 5.85* 0.875 10.14** 1.375 12.72** 1.875 14.85** 2.375 16.71 ** Q Total Q 5.0' weir FL@ 281 .5 (cfs) (cfs) 0 0 0 1.13 0 5.85 0 10.14 0 12.72 15.30* 20.15 215.00* 34.71 Holiday Inn Storage Routing Analysis Parameters t=60s Detention Pond Elevation Depth Discharge Storage 2 sit 2 sit+ 0 (ft) (ft) (0, cfs) (s, cf) 279.75 0.00 0 0 0.00 0.00 280.00 0.25 1.13 34.90 1.16 2.29 280.50 0.75 5.85 796.68 26.56 32.41 281.00 1.25 10.14 3005.34 100.18 110.32 281.50 1.75 12.72 6982.27 232.74 245.46 282.00 2.25 20.15 14504.33 483.48 503.63 282.50 2.75 34.71 27029.68 900.99 935.70 3.0'x0.75' opening & 5.0' w1er at 281.50 22 Storage Routing Analysis Detention Pond 5-Year Storm Event Time Inflow 11+12 Outflow (min.) (cfs) (cfs) 2s/t-O 2s/t+O (cfs) 0 0.00 0.00 0.00 0.00 0.00 1 1.59 1.59 0.02 1.59 0.78 2 3.17 4.76 1.74 4.78 1.52 3 4.76 7.93 5.10 9.67 2.29 4 6.34 11 .10 9.58 16.20 3.31 5 7.93 14.27 14.83 23.85 4.51 6 9.52 17.45 20.62 32.28 5.83 7 11 .10 20.62 28.57 41 .24 6.34 8 12.69 23.79 38.46 52.36 6.95 9 14.27 26.96 50.09 65.42 7.67 10 15.86 30.13 63.26 80.22 8.48 11 17.45 33.31 77.80 96.56 9.38 12 19.03 36.48 93 .84 114.27 10.22 13 20.62 39.65 112.33 133.49 10.58 14 22 .20 42.82 133.16 155.15 11.00 15 23 .79 45.99 156.24 179.15 11.45 16 23 .00 46.79 179.21 203.03 11.91 17 22 .20 45.20 199.78 224.41 12.32 18 21.41 43.62 218.03 243.39 12.68 19 20 .62 42.03 233 .78 260.06 13.14 20 19.83 40.44 247 .13 274.22 13.55 21 19.03 38.86 258.21 285.98 13.89 22 18.24 37.27 267.16 295.48 14.16 23 17.45 35.69 274 .10 302.85 14.37 24 16.65 34.10 279 .15 308.20 14.53 25 15.86 32.51 282.41 311 .67 14.63 26 15.07 30.93 283 .99 313.34 14.67 27 14.27 29.34 283.99 313.34 14.67 28 13.48 27.76 282.49 311 .74 14.63 29 12.69 26.17 279 .58 308.66 14.54 30 11.90 24.58 275.34 304.16 14.41 31 11 .10 23.00 269 .86 298.34 14.24 32 10.31 21.41 263.19 291 .27 14.04 33 9.52 19.83 255.41 283.02 13.80 34 8.72 18.24 246 .59 273.65 13.53 35 7.93 16.65 236.78 263.24 13.23 36 7.14 15.07 226.04 251 .85 12.90 37 6.34 13.48 214.3 1 239.52 12.61 38 5.55 11 .90 201 .50 226.20 12.35 39 4.76 10.31 187.65 211 .81 12.08 40 3.97 8.72 172.81 196.37 11 .78 41 3.17 7.14 157.01 179.95 11.4 7 42 2.38 5.55 140.28 162.56 11 .14 43 1.59 3.97 122.67 144.25 10.79 44 0.79 2.38 104.21 125.05 10.42 45 0.00 0.79 84.93 105.00 10.04 e112-pond-3.0x 75-opening.x ls Storage Routing Analysis Detention Pond 5-Year Storm Event Time Inflow 11+12 Outflow (min.) (cfs) (cfs) 2s/t-O 2s/t+O (cfs) 46 0.00 0.00 67.44 84.93 8.74 47 0.00 0.00 51.88 67.44 7.78 48 0.00 0.00 38.04 51.88 6.92 49 0.00 0.00 25.72 38.04 6.16 50 0.00 0.00 16.12 25.72 4.80 51 0.00 0.00 9.52 16.12 3.30 52 0.00 0.00 5.00 9.52 2.26 53 0.00 0.00 1.89 5.00 1.55 54 0.00 0.00 0.02 1.89 0.93 55 0.00 0.00 0.00 0.02 0.01 56 0.00 0.00 0.00 0.00 0.00 57 0.00 0.00 0.00 0.00 0.00 58 0.00 0.00 0.00 0.00 0.00 59 0.00 0.00 0.00 0.00 0.00 60 0.00 0.00 0.00 0.00 0.00 e112-pond-3.0x.75-opening.xls Storage Routing Analysis Detention Pond 10-Year Storm Event Time Inflow 11 +12 Outflow (min.) (cfs) (cfs) 2s/t-0 2s/t+O (cfs) 0 0.00 0.00 0.00 0.00 0.00 1 1.79 1.79 0.02 1.79 0.88 2 3.58 5.37 2.16 5.39 1.62 3 5.37 8.94 6.08 11 .10 2.51 4 7.15 12.52 11 .23 18 .60 3.69 5 8.94 16.10 17.22 27.33 5.05 6 10.73 19.68 24 .70 36 .90 6.10 7 12.52 23 .25 34 .54 47.95 6.71 8 14.31 26 .83 46.48 61 .37 7.44 9 16.10 30.41 60 .29 76 .89 8.30 10 17.89 33.98 75 .76 94 .28 9.26 11 19.68 39.35 94.65 115.11 10.23 12 21.46 41 .14 114.54 135.79 10.63 13 23.25 42 .93 135.39 157.47 11.04 14 25.04 48.29 160.60 183 .68 11 .54 15 26.83 51 .87 188.29 212.47 12 .09 16 25.94 52.77 215.78 241.05 12 .64 17 25.04 50.98 240 .09 266.76 13.33 18 24.15 49.19 261.32 289.28 13 .98 19 23.25 47.40 279.64 308.72 14 .54 20 22.36 45.61 295.22 325.25 15.02 21 21.46 43.82 308 .21 339.04 15.41 22 20.57 42 .03 318 .78 350.25 15.74 23 19.68 40.25 327 .04 359.02 15.99 24 18.78 38.46 333.15 365.50 16 .17 25 17.89 36.67 337 .22 369.82 16 .30 26 16.99 34.88 339 .37 372.10 16 .36 27 16.10 33.09 339.71 372.46 16 .38 28 15.20 31 .30 338 .35 371.01 16 .33 29 14.31 29.51 335.37 367.86 16 .24 30 13.42 27.72 330.89 363.10 16 .11 31 12.52 25.94 324 .97 356.82 15.92 32 11 .63 24.15 317.71 349.12 15.70 33 10.73 22 .36 309 .19 340.07 15.44 34 9.84 20 .57 299.46 329.76 15.1 5 35 8.94 18.78 288 .61 318.24 14.81 36 8.05 16.99 276.71 305.61 14.45 37 7.15 15.20 263.80 291.91 14 .06 38 6.26 13.42 249.94 277.21 13.63 39 5.37 11 .63 235.20 261 .57 13 .18 40 4.47 9.84 219 .62 245.04 12 .71 41 3.58 8.05 202 .90 227.66 12 .38 42 2.68 6.26 185.11 209.16 12 .03 43 1.79 4.47 166 .28 189.58 11 .6 5 44 0.89 2.68 146.44 168.96 11.26 45 0.00 0.89 125 .64 147 .33 10.85 e112-pond-3.0x.75-opening.xls Storage Routing Analysis Detention Pond 10-Year Storm Event Time Inflow 11+12 Outflow (min .) (cfs) (cfs) 2s/t-0 2s/t+O (cfs) 46 0.00 0.00 104.78 125.64 10.43 47 0.00 0.00 84.71 104.78 10.03 48 0.00 0.00 65.41 84.71 9.65 49 0.00 0.00 46 .84 65.41 9.28 50 0.00 0.00 33.55 46 .84 6.64 51 0.00 0.00 21.73 33.55 5.91 52 0.00 0.00 13.37 21.73 4.18 53 0.00 0.00 7.64 13.37 2.87 54 0.00 0.00 3.70 7.64 1.97 55 0.00 0.00 1.00 3.70 1.35 56 0.00 0.00 0.01 1.00 0.49 57 0.00 0.00 0.00 0.01 0.01 58 0.00 0.00 0.00 0.00 0.00 59 0.00 0.00 0.00 0.00 0.00 60 0.00 0.00 0.00 0.00 0.00 e112-pond-3.0x.75-opening xis Storage Routing Analysis Detention Pond 25-Year Storm Event Time Inflow 11+12 Outflow (min.) (cfs) (cfs) 2s/t-0 2s/t+O (cfs) 0 0.00 0.00 0.00 0.00 0.00 1 2.04 2.04 0.03 2.04 1.01 2 4.09 6.13 2.69 6.16 1.74 3 6.13 10.22 7.32 12.91 2.79 4 8.18 14.31 13 .31 21 .63 4.1 6 5 10.22 18.40 20.23 31 .71 5.74 6 12.27 22.49 29 .89 42.72 6.42 7 14.31 26.58 42.12 56.47 7.17 8 16.36 30.67 56 .64 72.79 8.07 9 18.40 34.76 73 .20 91.40 9.1 0 10 20.45 38.85 91 .71 112.05 10.17 11 22.49 44.98 115.40 136.69 10.64 12 24.54 47.03 140.16 162.43 11 .13 13 26.58 49.07 165 .94 189.23 11.65 14 28.63 55.21 196 .63 221 .15 12.26 15 30 .67 59.30 229.89 255.93 13.02 16 29.65 60.32 262 .19 290.20 14.01 17 28.63 58.27 290.70 320.46 14.88 18 27.60 56.23 315.65 346.93 15.64 19 26.58 54.18 337.24 369.84 16.30 20 25.56 52.14 355.65 389.38 16.86 21 24.54 50.09 371 .08 405.75 17.33 22 23 .51 48.05 383 .69 419.13 17.72 23 22.49 46.01 393 .65 429.70 18.02 24 21.47 43.96 401 .11 437.62 18.25 25 20.45 41.92 406 .22 443.03 18.41 26 19.42 39.87 409 .10 446.09 18.49 27 18.40 37.83 409.89 446.93 18.52 28 17.38 35.78 408.71 445.67 18.48 29 16.36 33.74 405.67 442.45 18.39 30 15.34 31 .69 400.87 437.36 18.24 31 14.31 29.65 394.43 430.52 18.05 32 13.29 27.60 386.43 422.03 17.80 33 12.27 25.56 376.96 411 .99 17.51 34 11.25 23.51 366.11 400.48 17.18 35 10.22 21.47 353.96 387.58 16.81 36 9.20 19.42 340.58 373.39 16.40 37 8.18 17.38 326.05 357.96 15.96 38 7.16 15.34 310.42 341 .38 15.48 39 6.13 13.29 293.77 323 .71 14.97 40 5.11 11 .25 276.15 305.01 14.43 41 4.09 9.20 257.61 285.35 13.87 42 3.07 7.16 238.22 264.77 13.28 43 2.04 5.11 217.97 243.33 12.68 44 1.02 3.07 196.53 221 .04 12 .2 5 45 0.00 1.02 173.94 197 .55 11.81 e112-pond-3 .0x75-openin g.xls Storage Routing Analysis Detention Pond 25-Year Storm Event Time Inflow 11 +12 Outflow (m in.) (cfs) (cfs) 2s/t-0 2s/t+O (cfs) 46 0.00 0.00 151 .23 173.94 11 .35 47 0.00 0.00 129.39 151.23 10.92 48 0.00 0.00 108.38 129.39 10.50 49 0.00 0.00 88 .31 108.38 10.03 50 0.00 0.00 70.46 88.31 8.93 51 0.00 0.00 54 .57 . 70.46 7.95 52 0.00 0.00 40.43 54 .57 7.07 53 0.00 0.00 27 .84 40.43 6.29 54 0.00 0.00 17.58 27 .84 5.13 55 0.00 0.00 10.52 17 .58 3.53 56 0.00 0.00 5.68 10.52 2.42 57 0.00 0.00 2.36 5.68 1.66 58 0.00 0.00 0.08 2.36 1.14 59 0.00 0.00 0.00 0.08 0.04 60 0.00 0.00 0.00 0.00 0.00 e112-pond-3.0x.75-opening.xls Storage Routing Analysis Detention Pond 50-Year Storm Event Time Inflow 11 +12 Outflow (min.) (cfs) (cfs) 2s/t-0 2s/t+O (cfs) 0 0.00 0.00 0.00 0.00 0.00 1 2.32 2.32 0.05 2.32 1.13 2 4.63 6.95 3.26 7.00 1.87 3 6.95 11.58 8.65 14.85 3.10 4 9.27 16.22 15.53 24.87 4.67 5 11.58 20.85 24.24 36.38 6.07 6 13.90 25.48 36.12 49 .73 6.80 7 16.22 30.12 50.81 66 .24 7.71 8 18.53 34.75 68.01 85 .56 8.78 9 20.85 39.38 87.43 107 .39 9.98 10 23.17 44.02 11 0.36 131.45 10.54 11 25.48 50.97 139.10 161.33 11 .11 12 27.80 53 .28 168.97 192 .39 11.71 13 30.12 55.60 199.93 224.57 12.32 14 32.43 62.55 236.06 262.48 13.21 15 34.75 67.18 274.48 303.24 14.38 16 33.59 68.34 311 .78 342 .82 15.52 17 32.43 66.03 344.74 377 .80 16.53 18 31 .28 63 .71 373.63 408.45 17.41 19 30.12 61 .39 398.67 435.02 18.18 20 28.96 59.08 420.09 457 .75 18.83 21 27.80 56.76 438.09 476.85 19.38 22 26.64 54.44 452.87 492.53 19.83 23 25.48 52 .13 464.60 504.99 20.20 24 24.33 49.81 473.38 514.41 20.51 25 23.17 47.49 479.41 520.87 20.73 26 22.01 45.18 482.87 524.59 20 .86 27 20.85 42 .86 483.94 525.73 20.89 28 19.69 40.54 482 .78 524.48 20 .85 29 18.53 38.23 479.53 521 .00 20 .74 30 17.38 35.91 474.3 5 515.44 20 .55 31 16.22 33.59 467.35 507.94 20.30 32 15.06 31 .28 458.61 498.62 20.01 33 13.90 28.96 448.19 487.57 19 .69 34 12.74 26.64 436.19 474.83 19.32 35 11.58 24.33 422.70 460.52 18.91 36 10.43 22 .01 407.80 444.71 18.45 37 9.27 19.69 391.57 427.49 17 .96 38 8.11 17.38 374 .10 408.95 17.43 39 6.95 15.06 355.44 389.16 16 .86 40 5.79 12.74 335.68 368.19 16 .25 41 4.63 10.43 314.87 346.11 15.62 42 3.47 8.11 293.08 322 .98 14 .95 43 2.32 5.79 270.36 298.87 14.26 44 1.16 3.47 246.76 273.83 13 .54 45 0.00 1.16 222.34 247.92 12.79 e112-pond-3.0x. 75-opening.xls Storage Routing Analysis Detention Pond 50-Year Storm Event Time Inflow 11+12 Outflow (min.) (cfs) (cfs) 2s/t-0 2s/t+O (cfs) -- 46 0.00 0.00 197.78 222.34 12.28 47 0.00 0.00 174.16 197.78 11.81 48 0.00 0.00 151.44 174.16 11.36 49 0.00 0.00 129.59 151.44 10.93 50 0.00 0.00 108.58 129 .59 10.51 51 0.00 0.00 88.49 108.58 10.04 52 0.00 0.00 70.61 88.49 8.94 53 0.00 0.00 54.71 70.61 7.95 54 0.00 0.00 40.55 54 .71 7.08 55 0.00 0.00 27.95 40.55 6.30 56 0.00 0.00 17.65 27.95 5.15 57 0.00 0.00 10.58 17.65 3.54 58 0.00 0.00 5.72 10.58 2.43 59 0.00 0.00 2.38 5.72 1.67 60 0.00 0.00 0.09 2.38 1.14 e112-pond-3.0x.75-opening.xls Storage Routing Analysis Detention Pond 100-Year Storm Event Time Inflow 11+12 Outflow (min.) (cfs) (cfs) 2s/t-O 2s/t+O (cfs) 0 0.00 0.00 0.00 0.00 0.00 1 2.42 2.42 0.12 2.42 1.15 2 4.84 7.25 3.52 7.37 1.93 3 7.25 12.09 9.17 15.61 3.22 4 9.67 16.93 16.38 26.10 4.86 5 12.09 21.76 25.81 38.14 6.17 6 14.51 26.60 38.50 52.41 6.95 7 16.93 31.43 54.11 69.94 7.92 8 19.34 36.27 72.29 90.38 9.04 9 21.76 41.11 93.00 113.40 10.20 10 24.18 45.94 117.57 138.94 10.69 11 26.60 50.78 145.85 168.35 11.25 12 29.02 55.61 177.71 201.47 11.88 13 31.43 60.45 212.99 238.16 12.58 14 33.85 65.29 . 250.95 278.28 13.66 15 36.27 70.12 291.28 321.07 14.90 16 35.06 68.91 290.14 319.86 14.86 17 33.85 68.91 327.08 359.06 15.99 18 32.64 66.50 359.61 393.57 16.98 19 31.43 64.08 387.99 423.68 17.85 20 30.23 61.66 412.45 449.64 18.60 21 29.02 59.24 433.23 471.69 19.23 22 27.81 56.82 450.54 490.05 19.76 23 26.60 54.41 464.55 504.94 20.19 24 25.39 51.99 475.37 516.54 20.59 25 24.18 49.57 483.20 524.94 20.87 26 22.97 47.15 488.25 530.35 21.05 27 21.76 44.73 490.71 532.98 21.14 28 20.55 42.32 490.74 533.02 21.14 29 19.34 39.90 488.52 530.64 21.06 30 18.14 37.48 484.19 526.00 20.90 31 16.93 35.06 477.90 519.25 20.68 32 15.72 32.64 469.77 510.54 20.38 33 14.51 30.23 459.91 500.00 20.05 34 13.30 27.81 448.33 487.72 19.69 35 12.09 25.39 435.14 473.72 19.29 36 10.88 22.97 420.43 458.11 18.84 37 9.67 20.55 404.29 440.99 18.35 38 8.46 18.14 386.80 422.43 17.81 39 7.25 15.72 368.04 402.52 17.24 40 6.05 13.30 348.08 381.34 16.63 41 4.84 10.88 326.98 358.96 15.99 42 3.63 8.46 304.83 335.45 15.31 43 2.42 6.05 281.67 310.87 14.60 44 1.21 3.63 257.56 285.29 13.87 45 0.00 1.21 232.56 258.77 13.10 e112-poncl-3.0x.75-opening.xls Storage Routing Analysis Detention Pond 100-Year Storm Event Time Inflow 11+12 Outflow (min.) (cfs) (cfs) 2s/t-0 2s/t+O (cfs) 46 0.00 0.00 207.62 232.56 12.47 47 0.00 0.00 183.62 207 .62 12.00 48 0.00 0.00 160.54 183.62 11 .54 49 0.00 0.00 138.35 160.54 11 .10 50 0.00 0.00 117.00 138.35 10.68 51 0.00 0.00 96.46 117.00 10.27 52 0.00 0.00 77.71 96.46 9.38 53 0.00 0.00 61 .02 77 .71 8.34 54 0.00 0.00 46.17 61 .02 7.43 55 0.00 0.00 32.95 46.17 6.61 56 0.00 0.00 21 .19 32.95 5.88 57 0.00 0.00 13.01 21.19 4.09 58 0.00 0.00 7.39 13.01 2.81 59 0.00 0.00 3.53 7.39 1.93 60 0.00 0.00 0.88 3.53 1.32 e112-pond-3.0x.75-opening.xls APPENDIXE Table 1.2-Twin City Church of Christ Drainage Report Drainage Report October 2003 Twin City Church of Christ Table 1.2 Runoff Quantities for Basin #3 Point of Study Existing Conditions and Developed Conditions with Detention Existing Runoff , Proposed Runoff lncrease/(Decrease) (cfs) (cfs) (cfs) Stonn Frequency (yr) Stonn Frequency (yr) Stonn Frequency (yr) 2 I 5 110 1 25 so 1 100 2 5 10 . 25 50 100 2 5 10 1 25 50 100 2.10 I 3.38 I 3.85 I 4.43 5.04 I 5.26 2.54 3.27 3.68 4.17 4.73 4.95 (0.16) (0.11) co.1n I co.26> (0.31) (0.31) As can be seen from the above table, the proposed development with the detention facility will decrease the amount of runoff that is currently being discharged at the Point of Study for Basin #3. CONCLUSION Compliance with City Standards From the information that is presented in this report, we have shown that the development of this site will meet the City's policy. Effectiveness .of Drainage Design The proposed drainage pla'n shows how the stormwater will be conveyed onto the adjacent street and property. The installation of a detention facility for the Basin #3 will help control runoff being discharged onto the adjacent property. Explanation of the Effectiveness of Existing and Proposed Improvements The creation of the detention facility for this project allows the increase in runoff to be detained on site so that the discharge off of the site is less than the existing undeveloped conditions. Upon review of the design calculations, the detention facilities will be capable of handling all storm events from a 2-year storm to a 100-year storm. 4 APPENDIXF Hydrographs 35 - 0 --+-----+ I ,i I I '- + --;------'- I ' -- I ~ : I ~ 11 I + 10 I ' ' { I I ' 20 Holiday Inn 5-Year Storm Event I ~--I 30 40 Time (min.) 50 60 I-Existing Conditions - -Developed Conditions -Developed Cond itions w/ Detention I 70 30 25 20 -I/) ..... () Q) -15 (13 0:: ~ 0 u. 10 5 0 I _J_ I -~ ~ f I I -~-t--' t -1--j- I '- ~ '=!f J1 I ..... -----+--1 I I '+--j I k ~t 1-. I J ~ I ,f 7 I ',/' -+-J + -+---~ - '/ +----- --l- I Holiday Inn 10-Year Storm Event I I I I I I I --+--+--+--+--l-l--+---+---+--1---+----+--+--+-l-l----+---f--+---I-, I ~ ~+--;---~ I I --t--I I I I ... --~ "' I L ~"'-+---+---+ r-- I I '~ - I I I I , .... ~I " -......... I I -1----~ r-_;_"'-~~ ·+11~ ..... ....... " --t I'-. I "' I I - i"'lio.....· i ...........i.. ......,,.. t --= t -r -~ I I I I I ~ '"I ..... --t-f f ·f' I 1 ~ "' ....,,,, "' ~~ ~I TJ -+-I --+-I -+-1--.1-\ ~ -I t=:= ~ : ~ + -!------)_ I '-I I ~ ---, I L t--~ J_ ----I- -+-t --+---~ 'I ' '-I I'- 0 10 20 30 40 50 60 70 Time (min .) I-Existing Cond itio ns - -Devel oped Conditions -Developed Conditions w/ Detention I 35 30 25 -~ ~ 20 Q) -ra 0:: 3: 15 0 u. 10 5 0 ~ . I I i -I __,_ -,~ I -,---'--4 + I ' I ____,_ I I " I -+------+--- + + . I + -+ I ,, '" I-~l I I -P ri I ' .-;>< I j + + 1 1 ! '/- + ;, ! i 1 / ~I! ,;/( t i--t I j/ -+ -· + -_[ -+ I T I Holiday Inn 25-Year Storm Event I I I I I I t I =+=~ t J_ ' I ! : i -t t +-t-~ ------"--+ --+----+ """"" ! l=t i I I I ,-1---I .......,.... 1-4-l"°"'oo- I .......... -+--" ~ .......... -~ " ......... ...... ,_I I I I '-~ I I .... ' I fl ~ -l---+- i i ... ' ' " I • I I I I _ _L_ I I ! I I --.....,_ I I I I I ± "I , i ,I_ I ..... +-- +-. t-t---= ist -1-L + .. 0 10 20 30 40 Time (min.) I Li I t- --+--I t -I I I i -+--i t-I ~~ ~ T -+-+--I I 1 I ------r--_j I I l l -.. I t ----r-t j--~ + ·1 i I f ,. t- + T ~+ I I I I I I f i +---+ ------+-L -I j--t--t + + --+--__j --i i ... ___J___,_ I j -j--... =Ff I -~ I -t-I I -j· t -· -+ ...... , ...... I t-+ ' I I I I i -: ~ ! ' --t-----+-~ I'-• ~ t-\. I L --t -t--l " I . -...... ~ t ~ i t 50 60 I-Existing Co nd itions - -Developed Co nd iti ons --Developed Conditions w/ Detention I - 70 0 10 20 Holiday Inn 50-Year Storm Event 30 40 Time (min.) 60 I-Existing Conditions - -Developed Conditions -Developed Conditions w/ Detention I 70 40 35 30 en 25 -(.) -Q) -20 "3 ~ ~ 0 LL 15 10 5 0 --+-- --+---+ + ""-t--r ' I --;---- + + ' -I + -----'--- I '-- I t' I + + I .. I ~ -· -+ +- ----+ =+ ~ i-----. Holiday Inn 100-Year Storm Event I I I I I I I I I i ! ! + ~ + : I I • I i i ~ i-. -+-------+ I : -r '--.----+--t -t I I I ! ~~ -T i += ~ t' r---+--- 4-T + -'-i It I I ! J I + f t-+ i T ' ~-, --'----+--I : I ----r----+ -+ ,.~ I--+-t _j_ i + +-+ I t --r-i I r + I -Ir-"-+ ' +-I '-I I I I I I I i ! i~ ,_+ L± I I I ' ;-I ~-+-I -I I -1 ~ I ----I I J / ~ ·--t-t-'---± -1 ~Ht= -i=Ct L + ~ --+ • -+--. ,....,.. . -~ '1 ~ ~ ' -· ~ + t ~ l_ , ---... I . . ;}fJt= ,lo. ' ._,I J I I -----+-- 'I I-+ ~r--r..... 1$ ~-· +-----+-' I ~ .... t I I '-I __,,..._ . -t t -i--· -I .-I :-... 1" I I I ~'!/ i tt i =± ! I I .... ' t-f--+ -±--j-"""' I' " ' I ... I -I I ---i-.. ..... T I ' I ~ 7 J_ ~ i-m .. ~ I I =ttn; "'---~ tf I ~-I I + ~ 1 t I ~ ,, I 1 --+ -I l r I'--~ -+ I 0 10 20 30 40 50 60 70 Time (min .) I-Existing Cond it ions - -Developed Cond itions -Deve loped Co nditions w/ Detention I EXHIBIT A Pre-Development Drainage Area Map -ll EXHIBIT B Post-Development Drainage Area Map 43 EXHIBIT C Liberty Subdivision Lot 2 Grading & Drainage Plan 45 EXHIBITD Holiday Inn Grading & Drainage Plan 47