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The overall runoff from each subbasin was estimated using the rational method using a C value of <br />0.45 and rainfall intensity values from Harris County Flood Control District. Table 7 presents the <br />drainage area data and peak runoff for each outfall in the Glen Meadows subdivision. <br />Table 7 Glen Meadows Rational Method Calculations <br />Outfall <br />Drainage <br />Time of <br />Q, 2-YR <br />Q, 5-YR <br />Q, 10-YR <br />Q, 25-YR <br />Q, 100- <br />Outfall <br />Size <br />Area <br />C <br />Concentration <br />(CFS) <br />(CFS) <br />(CFS) <br />(CFS) <br />YR (CFS) <br />(in) <br />(acres) <br />(min) <br />1 <br />54 <br />76 <br />1 0.45 <br />36.44 <br />95.03 <br />123.66 <br />143.06 <br />167.24 <br />203.43 <br />2 <br />1 36 <br />1 14 <br />1 30.92 <br />19.20 <br />1 24.79 <br />1 28.59 <br />1 33.33 <br />1 40.38 <br />3 <br />60 <br />70 <br />36.13 <br />87.96 <br />114.41 <br />132.34 <br />154.68 <br />188.12 <br />Total <br />- <br />160 <br />- <br />- <br />202.19 <br />262.85 <br />303.99 <br />355.25 <br />431.93 <br />Though detailed analysis was not conducted for the neighborhood drainage system, we believe <br />the neighborhood storm sewer system was designed for 2-year storm event. <br />North Avenue 11 (North ofA sport) Hydraulic Analysis <br />There are two airport channels that run along the northern border of the airport property, that <br />converge before turning to flow south. The typical cross section for the converged channel is <br />shown below in Figure 7. <br />North Airport Ditch <br />- Typical Cross Section <br />23.0 <br />_................ Neighborhood <br />......................Airport Property <br />22.5 <br />22.0 <br />w <br />c <br />0 <br />21.5 <br />w <br />21.0 <br />20.5 <br />20.0 <br />0 <br />10 20 <br />30 40 50 60 <br />Station <br />Figure 7 Northern Channel Typical Cross Section <br />La Porte Municipal Airport - Offsite Drainage Analysis <br />HT&J, LLC, January 2018 Page 13 <br />