10-13-08 Drainage and Flooding Committee minutes

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k lot z 4~~ ass 0 cia t e s be provided to drain away accumulating runoff waters, a localized drainage problem can be possibly resolved. Improved sheet flow pathways were identified for use in the five City-Identified Drainage Problem Areas discussed in Section 2.3.4 above. 2.4.2 Flow Path Elevation Adjustment Sheet flow drainage is sometimes prohibited by the elevation of a street, parking lot, or other large open area. Lowering of such areas can promote more effective sheet flow. This strategy was used in addressing some of the drainage problems in the City-Identified Drainage Problem Areas listed in Table 2-2. Table 2-6 and Exhibit 2-13,2-14,2-15 and 2-16 shows the cost and locations of possible sheet flow paths. Detail information on elevation and flow path direction is required to implement this improvement strategy. 2.4.3 Storm Sewerage Improvements Storm Sewerage, the set of pipes and appurtenances composmg a system, may be inadequate because of several causes: . Insufficient inlet capacity, which may be the result of insufficient size or type of inlet, insufficient number or spacing of inlets, inadequate street grading toward the inlet, or shifting of the elevation of a street or inlet which inhibits flow into the inlet. . Inadequate sewer pipe capacity, which may be the result of insufficient size, too shallow of a pipe slope, or excessive energy losses due to pipe material or junction conditions. . Outfall limitations which limit the maximum discharge from a sewer, due to outfall pipe material, size, or slope. . Incorporation of sheet flow options to provide addition drainage capabilities and prevent excessive ponding can be considered a particular type of sewerage 2-10 Klotz Associates Project No. 0127.008.000 January 2009 La Porte Citywide Drainage Study City of La Porte