Agenda - Public Works Committee - 01/17/2017

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4. PROPOSED IMPROVEMENTS 4.1 Street and Stormwater Improvements The segment of Alpine Drive between Armstrong Boulevard and Variolite Street is part of the City's Municipal State Aid System (MSAS). The proposed improvements must therefore be designed and constructed in accordance with current Minnesota Department of Transportation (MnDOT) State Aid standards which are generally based on the street's functional classification, projected traffic volume, design speed, lane designations and widths, and proposed pedestrian facilities. Based on the proposed design, Alpine Drive must be reconstructed in accordance with State Aid Rule 8820.9936 or 8820.9946. This will depend on the percentage of damaged curb and gutter that needs to be removed and replaced, which will be determined during final design. The scope of the proposed surface improvements is shown in Figure 1 in Appendix A. 4.1.1 Street Improvements Alpine Drive is proposed to be reconstructed with bituminous pavement matching the existing width. This design will meet current State Aid standards. All damaged B618 concrete curb and gutter is proposed to be removed and replaced in kind. A typical section for the proposed pavement reconstruction improvements is shown in Figure 2 in Appendix A. The proposed reconstructed pavement design must accommodate a 10-ton design in accordance with State Aid design standards. City staff is proposing a pavement section design of 1.5 inches bituminous wear course, 2 inches bituminous base course, and 6 inches of aggregate base composed of full depth reclamation material. This pavement section would be constructed over the existing subgrade after it is reshaped and compacted. The proposed pavement design should result in a minimum pavement life of 30 years, assuming that proactive, regular pavement maintenance treatments are performed during the life of the pavement. While staff would typically target a 60-year design life for reconstructed streets,this project is not proposing to remove and replace all curb and gutter due to the good condition of the existing 15 year old curb and gutter. Therefore, it may make sense to replace the pavement section at the time the existing curb and gutter is replaced, which will likely be 30 or more years into the future. 4.1.2 Stormsewer Improvements The existing storm sewer system is in good condition but will require the addition of three catch basins and 100 feet of storm sewer pipe to meet all current State Aid standards. In addition, several catch basin castings will require minor improvements. No stormwater quality treatment improvements are required for this project since the street is proposed to be reconstructed at its current width. Feasibility Report Alpine Drive Reconstruction City of Ramsey Project No.I7-0I Page 6