Agenda - Public Works Committee - 11/21/2023

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2023. The streets within the White Pines Estates subdivision were built in 1977. Pavement maintenance has included initial crack seal / seal coat improvements in 1984 and 1992. An overlay was performed in 2001, and the only pavement maintenance project since was a crack seal / seal coat improvement in 2009. Maintenance crews have performed patching as needed over the last several years. Proposed Improvements Staff review of the geotechnical report found generally sandy subsoil make up the roadway embankment throughout the project area. There are areas of silt and highly plastic clay below the roadway embankment 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 street 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 reconstruction, the in -slopes will likely be disturbed approximately 3 to 5 feet off of the edge of pavement. No changes to the current drainage pattern 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 stormwater within these subdivisions drain to a ditch located on 16512 Germanium Street. Existing there is a large bump in the road at the culvert crossing location to this outlet, because of the lack of clearance above the pipe. This project proposes raising Germanium Street approximately 1-foot to allow clearance over the new crossing pipe. This will require the driveway at 16512 to be replaced further back, and additional grading to match into the new roadway, however, work is still anticipated to be contained within the right-of-way. Special Concrete Driveway During the project open house held on November 2, 2023, Staff was made aware of two special concrete aprons. Initial review shows the driveways having colored concrete, and a stamped design. Previous practice on reconstruction projects is to replace the materials and patterns to match existing as best as practical. This is achieved by having a special concrete driveway pay item, and special provision in the specifications. It has required that City Staff coordinate with the Contractor and Property Owner to go over the special concrete, and potentially have the property owner present during the concrete pouring. In the past, this has been difficult to achieve, and has required removal and replacement of concrete several times to meet home owners' expectations. Staff would like to discuss the following options moving forward with special concrete driveway replacements: • Continue to replace back concrete driveways to match existing as best as practical • Replace back special concrete driveways with standard concrete, within the right-of-way