Drainage_and_Flooding_Report-dated_03-10-08

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Mr. Ron Bottoms March 10, 2008 Page 9 of 15 k I o t z associates A storm sewered pipe system along this same alignment could also work but construction easements would be needed to place the pipe. This would probably be more expensive than the open ditch system but would require less ROW. Constructing a storm sewer system from the Park due north across the park to H Street would require an easement across one of the properties due north from the Park. Additionally the drainage along H Street will have to be evaluated to make sure that what ever improvements are made that the street drainage can be improved to handle the drainage. This project would be the shortest distance and may prove to me more economical to construct if one of the property owners works with the City on the alignment and acquisitions of the needed ROW and if the H Street drainage can be improved to handle the flows. Recommend that the City work with one of the property owners due north of the Park to determine if a suitable and available ROW can be worked out along this shorter path. This may prove to be the best alignment. Coordination with HCFCD will be required if a new outfall pipe is constructed. Short Term Drainage Project 3. Drainer e Im ravemerrts alon Dri twood Dave This area is located between Fairmont Parkway and Spencer Highway (see Exhibit 8). The area is drained by a storm sewer system. Currently the storm sewer from areas north of the detention basin sends flows through the storm sewer in a southerly direction. During rainfall events, some of the southbound flows intersect the existing manhole, head west, and then go to a HCFCD ditch while some of the flows backup eastward into the detention basin on the east side of the road. There is also a storm sewer system that conveys flows northward toward the detention basin from areas south of the basin. Drainage plans show the existing two storm sewer systems (48" from the north and 36" from the south). During heavy rainfall events water backs up in Driftwood Drive with some flows coming to Driftwood Drive from the Fleetwood Drive area making the ponding along Driftwood even worse. Remedy of the current flooding problems should consider enlarging the sewer outfall pipe from Mesquite to the ditch and detention basin to provide for sheet flow in this same area. Relief sheet flow pathways for backup runoff waters could include buyout of the house at the intersection of Mesquite and Driftwood. The City provided Klotz Associates a set of plans dated 2-21-08 that is aimed at relieving some of the hydraulic impacts along Driftwood Drive. The drainage plans show a new 36" outfall from Driftwood into the detention basin. Comments to the current City plans: 1. The plans show the existing two storm sewer systems (48" from the north and 36" from the south). Are those two systems connected together under the road? If not it might be