Agenda - Council - 04/23/2024 - Laserfiche WebLink

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Review of ground penetrating radar(GPR), as-built plans, and the Bowers Drive Mill and Overlay Evaluation performed by Braun Intertec indicates three separate mill and overlay thicknesses will be used on the various street segments. Orchard Hills Townhomes subdivision does not have sufficient pavement thickness for a 2-inch mill and overlay improvements, therefore a 1.0-inch mill and 1.5-inch bituminous overlay will be used. The section of Cobalt Street between Alpine Drive and 152nd Lane is proposed to receive a full-depth mill and fill of approximately 3.5-inches. Bowers Drive will receive a full-depth mill and overlay of approximately 3.5-inches. The bituminous will be placed in 2 lifts. Additionally, some minor base corrections are anticipated to be required. All remaining subdivisions have sufficient existing bituminous thickness to perform a 2-inch mill and bituminous overlay. Per typical overlay improvements, spot concrete curb and gutter repairs will be performed on damaged curb. Where feasible,the City has switched to a saw& seal method for curb cracks at a significant cost savings. This is performed on hairline cracks,without vertical displacement. For areas of bituminous curbing, repairs to the curbing are not anticipated,though the City typically updates curb adjacent to storm sewer inlets to concrete during mill and overlay projects. Municipal sewer and water exist under all street segments in the project except for Bowers Drive. This project is not proposing any repairs to watermain or sanitary sewer. Minor storm sewer structure repairs, typically re-grouting catch basins, is proposed. Additionally,the project proposes adding hydrodynamic separators to the storm sewer system along Bowers Drive for the two outlets to the Mississippi River. The separators are a cost-effective TSS removal device,which is used in leu of infiltration basins. Infiltration basins would require significant surface area, grading, and drainage easements which the City do not currently have. Four of the townhouse subdivisions include extensive pedestrian ramps which do not meet current American with Disability Act(ADA) standards, and will require upgrades. A total of 50 pedestrian ramps were found to require upgrades, and will be replaced during construction. As an alternative bid item,this project also includes constructing the gravel segment of Basalt Street south of 141 st Avenue to a fully paved street section including concrete curb and gutter. The street will be built to a width of 36 feet,with parking on one side, and terminate in a cul-de-ac built to 66 feet in diameter. This is the largest cul-de-sac which will fit in the existing right of way. Staff reviewed options for increasing the cul-de-sac to the standard 100-foot diameter,but found it not feasible, largely due to the significant impacts on the existing commercial sites adjacent to the street. The pavement will be built to a 10-ton pavement strength design which is typical for commercial/industrial streets, this will be achieved by placing 4-inches bituminous on top of 6-inches aggregate base. Preliminary Schedule Remaining • Staff receives bids o June 4, 2024 •Council awards contract to the lowest responsible bidder o June 11, 2024 •Contractor begins construction o On or around July 8, 2024 (dependent on Contractor's schedule) • Substantial Completion o August 31, 2024 o Final lift of bituminous pavement in-place, concrete repairs compete,boulevard restoration in-place •Final Completion o September 30, 2024