Agenda - Council - 01/24/2017 - Laserfiche WebLink

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3. EXISTING CONDITIONS 3.1 Existing Pavement and Soil Conditions Based on record plans, this segment of Alpine Drive was constructed in 2001 with 3.5 inches bituminous pavement, 6 inches class 5 aggregate base, B618 concrete curb and gutter, and concrete storm sewer. However, field observations show that the 6 inch class 5 aggregate base was substituted with roughly 5 inches of recycled crushed concrete base. No information on the reason for this substitution could be found. The street was constructed to a width of 32 feet from face-of-curb to face-of-curb in locations where parking is restricted, and to 38 feet from face-of-curb to face-of-curb in locations where parking is allowed along one side. The street is centered within an 80 foot right-of-way, and striping is used to delineate the parking lanes. The only pavement maintenance treatment that has been applied to this segment of Alpine Drive was spot patching on an as-needed basis. In 2016, Staff observed a Pavement and Surface Evaluation Rating (PASER) of 3. In 2011, MnDOT recorded a traffic volume of 1,100 average annual daily traffic (AADT). While truck counts are not available, Staff believes it is reasonable to assume less than 5 percent of vehicles using this street segment can be classified as truck traffic, and that the percentage of trucks using this corridor will not substantially increase over time. The posted speed is 45 mph. Northern Technologies, Inc. (NTI) was employed to complete a Geotechnical Exploration and Engineering Review for this project, which included thirteen (13) soil borings that were spaced at approximately 200 feet along Alpine Drive. The locations of the borings are shown in the Boring Location Diagram in Appendix C of NTI's report, attached in Appendix C. The soil borings provide information on existing bituminous pavement and aggregate base course thicknesses, subsurface soil conditions, existing ground water elevations, and potential issues that may be encountered during construction. All borings terminated at a nominal depth of 11 feet below the existing ground surface. Groundwater was observed in two soil borings at depths ranging between 10 and 10.5 feet below the existing ground surface. Based on the work proposed and the recorded water level depths, groundwater is not anticipated to be a significant issue for work completed with this proposed project. The soil borings generally indicate that existing bituminous pavement thicknesses range between 3.5 to 5.0 inches. Apparent aggregate base was observed in five boring locations. Previously placed fill soils, generally consisting of poorly graded sand with silt and poorly graded sand with silt and gravel (SP-SM), poorly graded sand with clay (SP-SC), and clayey sand (SC) are present at depths ranging from 3.0 to 9.5 feet below the top of the pavement. Native alluvial soils consisting of poorly graded sand (SP) and poorly graded sand with silt(SP-SM)generally extend to the bottom of the borings. WSB and Associates (WSB)was employed to complete a total of four pavement corings. Their results showed an average bituminous pavement thickness of 4 inches, which was constructed over approximately 5 inches of recycled concrete base material. Feasibility Report Alpine Drive Reconstruction City of Ramsey Project No.I7-0I Page 4