Agenda - Council - 02/10/2015 - Laserfiche WebLink

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4. PROPOSED IMPROVEMENTS 4.1 Street and Stormwater Improvements 4.1.1 Garnet Street Garnet Street is proposed to be reconstructed with bituminous pavement and concrete curb and gutter which will better facilitate drainage over time. Numerous streets exist throughout the City with bituminous curbing and almost all of them are deteriorating more rapidly than streets with concrete curb and gutter due to their inability to rapidly convey drainage off of the pavement surface, particularly along edges of streets. The proposed surface improvements are shown on Figure 1 in Appendix A. Pathway/Sidewalk: New sidewalk segments are proposed to be constructed along the east side of Garnet Street to connect to existing concrete sidewalks located along the north side of 167th Avenue at the south end of the project, and along the east side of Garnet Street at the north end of the project, both of which are immediately available at the project termini Existing pedestrian facilities are shown on Figure 2 in Appendix A. Street Design: Garnet Street is currently an urban residential street with bituminous curb and pavement 31 feet in width from back -of -curb to back -of -curb. Existing and proposed traffic counts are consistent with typical residential streets. Garnet Street is proposed to be reconstructed maintaining its current width of 31 feet from back -of -curb to back -of -curb. NTI recommends a pavement section of 6" class 5 aggregate base, 2" bituminous base course, and 11/2" bituminous wear course. However, the City's standard residential street pavement section is 4" class 5 aggregate base, 2" bituminous base course, and 11/2" bituminous wear course. Based on the low traffic volumes on these streets, staff recommends using the City's standard residential street pavement section. NTI recommends completing a 12" minimum subgrade correction by scarifying and re - compacting existing poor subgrade soils, then test rolling the corrected soils after and checking for poor or unsuitable areas and making spot corrections as needed. NTI recommends also adding sub -drain pipe along the outside bottom edges of subgrade on all streets and plugging the drain pipe into storm sewer catch basins. However, NTI also suggests there will be a long-term potential for differential settling of the streets if the existing subgrade soils are scarified and re -compacted as per their recommendation. Staff is therefore recommending to correct all poor subgrade soils by excavating 3 feet of existing poor soils and replacing it with clean imported select granular borrow. This will provide a uniform subgrade section that will not be prone to differential settling over time and will therefore require less maintenance over time to reduce the City's long-term maintenance costs, and will maximize the life of the street. Feasibility Report Garnet Street and l68`" Avenue Reconstruction City of Ramsey Project No. 13-10 Page 9