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<br />- <br /> <br />The remainder of the culverts will convey the 100 year flood peak. The <br /> <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />upper reaches of Drainageway L become increasingly steep with slopes up <br /> <br />to 30%, <br /> <br />The flood hazards in this drainageway are erosion, sediment and debris <br /> <br /> <br />removal, interrupted traffic and services, and a moderate to high life <br /> <br />hazard caused by the deep flows and high velocities. In addition, significant <br /> <br />erosion problems will be encountered on the embankments of the detention <br /> <br />dams (roadways) caused by local street flows overtopping the curbs and <br /> <br />flowing down the unprotected embankments. <br /> <br />2. Station 38+30 to 0+00, Upstream Study Limits to Confluence <br />with Drainageway L (Sheets 81 and 82) <br /> <br />The channel in this reach, designated Drainageway L-1, is tributary <br /> <br />to Drainageway L at station 129+50, near the Devinny School. The channel <br />consists of a deeply incised V-shaped section with an average slope of <br />6.3%, The channel is crossed by Welch Street and Beech Street with 36" RCP <br />culverts and outlet stilling basins. The flood plain is contained <br />within the channel area, except at Beech Street, where the 100 year flood <br />peak overtops the street, <br /> <br />The flood hazards consist of erosion, debris removal and cleaning, <br /> <br />interrupted traffic and services, and a moderate to high life hazard due <br /> <br />to the steep channel and high velocity flows, <br /> <br />22 <br />