10-13-08 Drainage and Flooding Committee minutes

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k lot z f~. ass 0 cia t e s 5.2.7.2 Construction in Special Flood Hazard Areas While the City does allow under certain conditions construction in known floodplain areas (i.e., special flood hazard areas), the City should allow such construction only under very special circumstances. Experience has shown construction in special flood hazard areas is an invitation to flooding if such construction is not carefully designed with flooding issues fully recognized. Critical to allowing such construction, if the City feels it essential to proceed with such construction, is 1) requiring finished floor slabs to be above the lOa-year flood level; 2) requiring flood proofing of the ground floor structures; and 3) allowing such construction only in storage areas well beyond the floodway so that flood flow velocities are quiet small; 4) mitigation of fill in the floodplain along with any needed detention. Also to be recognized is that detailed flood flow analysis and floodplain delineation has not been accomplished for many of the smaller creeks, streams, and channels in the City. Thus locations of anticipated flooding when severe storm events occur are not accurately known at the current time. It would be to the City's benefit to conduct flood analyses that would delineate floodplain areas not currently known. 5.2.7.3 Minimum Low Chord Clearances New bridge or bridge modifications in the future should be sure to have low chord clearances in accord with City criteria. 5.2.7.4 Capacity Improvements in Storm Sewer Systems Review of storm sewer capacity should be considered in areas where this CWDS report has identified inadequate capacity as the likely key source of reported flooding in a particular area. In making such review, several factors should be considered: 1) what is 5-12 Klotz Associates Project No. 0127.008.000 January 2009 La Porte Citywide Drainage Study City of La Porte