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1) Northern Ditch Section (See Exhibit 3) - For approximately 1000 LF, the existing swale <br />will be expanded to 24 ft. bottom width channel, and the average depth is about 2.0 ft. The <br />existing drainage structure 24 will be replaced by a 24" pipe. This pipe functions as a <br />restrictor for this linear detention basin. This detention provides approximately 2.66 ac-ft. <br />of storage. <br />2) East Ditch Section - The right bank of the ditch (towards the airport side) will be sloped at <br />1% from the channel bottom to the existing ground elevation. The Ditch segments 7, 16, <br />and 21 are proposed to function as linear detention. The proposed channel section is about <br />300 ft. wide at the top (See Figure 10). The modifications to Ditch Segments 7 and 21 <br />provide approximately 4.80 ac-ft. of additional storage. <br />Improvements to the northern section involve about 7.5 ac-ft of soil excavation for both the linear <br />detention and conveyance improvement. <br />1? A <br />23 <br />22. <br />11. <br />20 <br />LLJ <br />19 <br />18 <br />1.d <br />00 <br />Linear Dtention, Catch Segment 21 <br />Prol:rorar-ed Ex6sUng. <br />-250 200 1.50 -1.00 -50 0 50 100 150 2R J <br />Station (rt) <br />Figure 10 Linear Detention Geometry <br />Other modifications to the ditch system include: <br />1) Several ditch sections will be lowered with minimal changes to bottom width or side slopes. <br />La Porte Municipal Airport — Offsite Drainage Analysis <br />HT&J, LLC, January 2018 Page 17 <br />