Agenda - Public Works Committee - 06/21/2016

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Public Works Committee 5. 1. Meeting Date: 06/21/2016 By: Bruce Westby,Engineering/Public Works Title: Provide City Council Recommendation for Gibbon Street and 173rd Avenue Drainage Improvements Feasibility Report Purpose/Background: Purpose: The purpose of this case is to provide a recommendation to the City Council for accepting the Gibbon Street and 173rd Avenue Drainage Improvements Feasibility Report(draft copy attached), and for moving forward with a project. Background: Over the years, City Staff has received numerous reports of flooding and wet basements from owners of properties located in various low-lying, land-locked areas of the City. The year 2014 was particularly wet resulting in numerous reports of flooding and wet basements. This included the property owners at 17421 Gibbon Street NW who contacted the City in the spring of 2014 with high water concerns. They stated that water was coming up through their basement floor from the adjacent wetlands. Staff visited the site in 2014 and observed that the surrounding wetlands were full and the water level was near the road two lots to the north. The flow direction was not readily apparent,though there may have been a slight cast to west flow indicating that water may flow to the north when water levels are high enough. Staff did not observe any water flowing over Gibbon Street,or that standing water was threatening to flood any homes. This area is land-locked meaning no overland drainage routes exist that are lower than the lowest openings of the homes in the area. On March 31, 2015, several property owners addressed the Public Works Committee to inquire if the City could do anything to help them with their drainage issues. Based on direction from the Public Works Committee,with subsequent ratification by the City Council, City Staff was directed to analyze the drainage areas for three areas that reported the most significant flooding issues in 2014. Brief background information on these three areas is included below. The areas are listed in order of priority based on the significance of the reported damage. Though several other property owners contacted the City about standing water on their properties during the 2014 spring snow melt, the three areas discussed herein continued to experience high water levels long after the snow melt was finished. Property owners from the other areas never contacted the City again which indicated that their issues were not as significant. Gibbon Street north of 173rd Avenue This area is in the Deerwood Plat which was platted in 1974. The area to the west was platted in 1991 as Wildwood Acres. Drainage and utility casements were recorded over some wetlands in the plat and over County Ditch 27 which runs across the north side of the plat and through wetlands that were not encumbered with drainage and utility casements. There are also drainage and utility casements along the lot lines from the ROW to the wetlands. This area is relatively flat with minimum elevation change. The residents at 17421 Gibbon Street NW reported high water levels around their home and water coming into the basement. The home is a split level style with a 4 foot basement. The nearest wetland and casement recorded on the plat are on the north side of the next lot to the north and extend onto the 2nd lot to the north. The address of the parcel with the majority of the wetland is 17511 Gibbon Street. There is a drainage and utility casement on the west side of Gibbon Street that connects to the casements on the Wildwood Acres plat. West of the Wildwood acres plat is an un-platted parcel. A County Ditch runs through this parcel. A drainage and utility casement exists west of Gibbon Street across from the wetland at 17511 Gibbon Street. This casement also connects with the casements on Wildwood Acres.