Agenda - Council - 02/26/2024 - Laserfiche WebLink

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due to the location of the subdivision and lack of destinations which would increase traffic above normal. Municipal sewer and water do not exist in the project area, and utility extensions to the area are not proposed. The existing drainage is through a combination of swales adjacent to the roadway, and on street drainage to curb cuts in the bituminous curbing area, as well as street crossing culverts. Additionally, Staff is aware of Northern Natural gas mainlines crossing in one location at 164th Lane, approximately 600 feet east of Trunk Highway 47. Proposed Improvements Staff review of the geotechnical report found generally sandy subsoil makes up the roadway embankment throughout the project area. There are areas of silt and highly plastic clay below the roadway embanlcrnent zone. These would only impact the project if excavation goes deeper than 3 to 4 feet, generally for storm sewer installation. Where these soils are found during pipe installation, the plans call for subsoil corrections in the immediate areas, and have quantities built into the plans to accommodate such a circumstance. In general, the current swales along the streets within the Barthel's Rum River Acres subdivision are not proposed to be re -graded as part of this project. Due to the nature of street reconstructions, the in -slopes will be disturbed approximately 6 feet off of the edge of pavement. No changes to the current drainage patterns are proposed. The existing culverts crossing the streets are proposed to be removed and replaced, this is to ensure the culverts will last at least through the proposed 60-year design life of the street. The bituminous curbing within the White Pines Estates subdivision is proposed to be replaced with surmountable concrete curb and gutter. At driveways, a curb cut similar to what is typically placed in B-style curb will be placed to avoid a high transition from the roadway to driveways. Additionally, concrete storm sewer inlets and piping will be added to better drain the urban section streets. As discussed previously, Staff is anticipating some subsoil corrections will be necessary as part of the storm sewer construction. This will consist of removing the poor soils and replacing with select granular sand, which is proper pipe bedding material. Restoration of the impacted boulevard areas will include a minimum of 4-inches topsoil and hydroseed with a residential turf seed mix. Though the pavement is generally going back to the same location and elevation, driveway aprons will be replaced to match into the new bituminous pavement as minor changes will occur. In general, driveway aprons will be going back 8 feet to tie the driveways into the new pavement. The majority of stonnwater within these subdivisions drain to a ditch located on 16512 Germanium Street. A significant bump in the pavement exists at the culvert crossing location to this outlet due to the lack of cover above the pipe. This project proposes raising Germanium Street approximately 1-foot at this location to provide additional cover over the new crossing pipe. This will require driveways in the immediate vicinity to be replaced slightly further back than other driveways so they will match the new roadway elevations. However, work is still anticipated to be contained within the right-of-way. Preliminary Schedule Remaining • Council Awards Contract to the Lowest Responsible Bidder o February 26, 2024 • Contractor Begins Construction o Spring 2024 • Contractor Substantially Completes Construction o New bituminous pavement in -place, topsoil and seed in -place o August 2, 2024 • Contractor Final Completion o Verify final restoration; punch list created o August 30, 2024 Permit Approvals Before construction can begin, Staff must obtain permits from MnDOT for a right of way permit, and Lower Rum River Watershed Management Organization for a grading, stormwater management and erosion / sediment