Drainage_and_Flooding_Report-dated_03-10-08

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Mr. Ron Bottoms March 10, 2008 Page 11 of 15 k I o t z associates At this time, the flow from severe storm event has to travel down Fleetwood Drive, then east down Mesquite Drive, and onto Driftwood Drive. The sheet flow for this area flows to the outfall location but the neighboring lots arc higher than the street and serve to restrict the flow, much like a levee. An emergency flow path, with needed easements, could be built between the houses of Mesquite Street and along the storm sewer of Fleetwood Drive could direct the sheet flow directly to HCFCD B106-02-00. Inlet capacity at the intersections of Fleetwood Drive is also limited, so another option to consider is adding additional sewer capacity using a pipe or pipes between houses. Recommend that discussions be held with the property owners of the two lots where the sheet flow path of new outfall pipe might be constructed to determine their willingness to work with the City on a potential solution for this area. Short Term Drainage Project 5. Glen Meadows Subdivision Interceptor Inlet Glen Meadows Subdivision is located off Spencer Highway and drains into Big Island Slough by a storm sewer system (see Exhibit 10). Spencer Highway is higher in elevation than this subdivision and some sheet flow drains from Spencer Highway into Glen Meadows. The intersection of Spencer Highway and Valley Brook Drive is a high point which allows ponding water trying to drain off of Spencer Highway. We reviewed the information of the storm sewer system for this area and noted only 9 inlets exist along Valleybrook. During heavy rainfall events the water from upstream areas will sheet flow south along Valleybrook to the lowest point near Meadow Crest Street. The available information indicates that the storm sewer system will surcharge and that there is no relief route for the flows to get out of this portion of Glen Meadows without flooding of some homes. Upsizing of the outfall pipe or a sheet flow path between a couple of homes appear to be good solution for drainage. The City has informed Klotz Associates that an intercept inlet(s) may be added to the Spencer Road drainage system. Adding inlets would increase the capacity which would allow the sheet flow to enter the storm sewer system and thus help to reduce the surface ponding in that area. Additional coordination with the County should continue to determine any future plans they may have for this area. Recommend coordination with the County on their potential work in the area along with a detailed evaluation to determine if a new larger pipe and or sheet flow path is best or if a drainage pipe could be economically constructed south along Valleybrook to Spencer Road then to Big Island Slough. Coordination with HCFCD will be required if a new outfall pipe is constructed.