CCP 05-10-1999 - Laserfiche WebLink

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I I r I I I I I I It I I I I I I I , I AREAS OF CONCERN/SUGGESTED REPAIRS Considering the extensive drainage system in the city relatively few problem areas were encountered during the field survey, Most of the drainage ways and wetland areas are in locations where problems caused by potential flooding are relatively low in severity. The majority of drainage ways are in ravines or channels, which are well below the elevation of any development or roadways, The vast majority of problems discovered are minor in nature and consist of replacing culvert end aprons, removing debris or sediment from culverts, etc, A few cases would involve a significant investment on the part of the city to remedy or keep in functioning order. The following are short descriptions ofthe more significant problem areas encountered during the survey, McClung Drive Problem The primary area of concern is a ditch that runs behind McClung Drive and Colleen Avenue, A resident at 1519 McClung drive has called the city reporting that the ditch has flooded numerous times in the last few years, The resident has stated that when the creek floods the water inundates their backyard and has come to within a foot of entering their walkout basement. The flooding can be attributed to a few reasons: * The walkout basement elevation is low compared to the creek bed and the backyard grade from the walkout to the creek is nearly flat. * The ditch bed behind the house up to the culvert outlet approximately 100 yards down stream is flat. As a result of the flat slope, flow velocity in the ditch bed is slow causing sediment to build-up, which fills in the stream channel. * The steep hill on the north side of the creek (Royal Hills Drive/Arden Vista Court) is lacking in vegetation, which tends to slow down storm water runoff flows. This ditch was cleaned by city crews a few years ago and has silted in and new vegetation has developed in the channel. The vegetation and sediment also acts to slow down storm water runoff flow rates, Potential Mitigation Measures * The primary mitigation measure is to clean the channel of sediment and debris to increase flow through the section. The inlet and outlet of the downstream culvert should also be cleaned out to maximize the flow capacity ofthe culvert. The steep slope on the north side of the channel should be stabilized to eliminate slope erosion and reduce the amount of sediment flow into the creek, It is likely that a periodic cleaning of this ditch will always be needed to maintain its usefulness, * Small check dams with stilling basins could be built along the ditch upstream of the problem area, The stilling basins would be constructed to hold more water upstream and reduce the flow through the area of the stream in question, This measure would require multiple stilling basins, 5