Agenda - Council - 07/09/2019 - Laserfiche WebLink

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Motion carried. Voting Yes: Chairperson Riley, Councilmembers Kuzma and Johns. Voting No: None. 6. COMMITTEE / STAFF INPUT 6.01: Review Drainage Concerns at 17290 Germanium Street NW City Engineer Westby stated that the property owner at 17290 Germanium Street NW informed the City Council on November 13, 2018 that he was concerned that the runoff from the Covenant Meadows residential development was flooding his property. He also stated that the City Engineer has been unresponsive to his concerns and requests. City Engineer Westby provided background information noting that the property owner at 17290 Germanium Street NW built their home in 1992. They built a garage in the southwest corner of the property in 1998, which was rebuilt in 2005 after the first garage burned down. The garage was constructed in a low area of the lot and was not elevated. The garage door faced a private property which was used to access Germanium Street approximately 300-feet to the east. In 2017, construction began on the Covenant Meadows residential development, which included construction of a new public street (172nd Lane NW) abutting the south property line of 17290 Germanium Street NW. During construction of this development, the property owner contacted City Staff and the developer on numerous occasions to request modifications to the new driveway installed between his garage and 172nd Lane NW. He also requested grading modifications to prevent drainage from entering his property from the north and west, noting he had issues with standing water on his property. City Engineer Westby stated that before Covenant Meadows was developed (pre -development), 11.125 acres of land drained onto this property from the north and the west, contributing 3.1 cubic feet per second of runoff from a 100-year storm event. After Covenant Meadows was developed (post -development), 1.306 acres of land drain onto this property from the north and the west, contributing 0.75 cubic feet per second of runoff from a 100-year storm event. He reviewed the memorandum from the Engineering Department outlining pre and post - development drainage conditions and displayed maps showing the pre and post -drainage areas that contribute runoff onto this property. City Engineer Westby reviewed the driveway modifications that have been made throughout this process which included a driveway constructed with a 15" driveway culvert but noted that the property owner was not satisfied as his work trailer bottomed out. He stated that two eight -inch culverts were then evaluated but during that process the property owner removed the culvert and regraded the driveway himself. The property owner objected to the use of any culverts. He stated that the property owner expanded the driveway using aggregate base provided by the developer, so there is now a 60-foot-wide driveway with no culvert. He stated that drainage is forced to flow over the driveway as constructed. City Engineer Westby reviewed drainage modifications noting that the property owner requested a swale to drain the pad west of the garage. He stated that the developer was still discussing options with the property owner when the property owner addressed the City Council. He stated Public Works Committee / December 18, 2018 Page 6 of 11