Agenda - Council - 01/08/2019 - Laserfiche WebLink

Home

3. EXISTING CONDITIONS 3.1 Existing Pavement, Soil, and Traffic Conditions All streets proposed to be improved were constructed in 1979 with 1.5-inches of bituminous pavement, 3.0-inches of aggregate base, and ditches. The streets are generally centered within a 66-foot wide right-of-way. Pavement maintenance treatments applied to the street segments included overlay in 1993, and crack seal and seal coat improvements in 2001. Spot patching has been performed on an as -needed basis, and has been a yearly treatment recently. In 2018, Staff assigned a PASER rating of 3 on both street segments. In September of 2018, City Staff recorded a traffic volume of 72 average annual daily traffic (AADT) on 173rd Avenue east of Germanium Street, and 278 AADT on Germanium Street north of 170th Lane. The speed limit is 30 mph for these street segments. Northern Technologies, LLC (NTI) was employed to complete a Geotechnical Exploration and Engineering Review for this project, which included seven (7) soil borings spaced evenly along 173rd Avenue and Germanium Street. The locations of the borings are shown in the Soil Boring Location Map 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, subgrade soil conditions, existing ground water elevations, and potential issues, which may be encountered during construction. The borings general terminated at a nominal depth of 10 feet below the existing ground surface, boring number 4 terminated at 20.5 feet as it was following a layer of clay. There was groundwater observed in 4 of 7 borings, with elevations varying from approximately 872.5 to 877, 6.5 to 9.0 feet below the existing surface. Based on the work proposed groundwater is not anticipated to be a significant issue for work completed with this proposed project. There is the small potential for groundwater impacts if storm sewer is required, and is placed at a depth greater than 6-feet below the existing ground. The soil borings generally indicate the existing bituminous pavement thickness ranges between 2 1/4 to 5 inches, and aggregate base thickness is 5 to 6 inches. The subgrade generally consists of poorly graded sand with silt, silty sand, and poorly graded sand. Below this 4 of the 7 borings had layers of lean clay with sand, clayey sand, and / or lean to fat clay. The depths of the layers varied among the borings, and the pockets with clay seemed to be spread out along the project. Braun Intertec was employed to complete a ground penetrating radar (GPR) analysis for the project area, which included driving the GPR equipped vehicle throughout all street segments within the project area. A summary table and charts of the GPR Analysis are attached in Appendix C. The GPR data determined a median bituminous pavement thickness of 3.6-inches, and a median aggregate base thickness of 2.7-inches. The median street pavement and base section thickness was 6.2-inches, with a minimum section of 3.7-inches located on Germanium Street, 310 feet north of 173rd Avenue. GPR data was not able to be obtained for 173rd Avenue. Feasibility Report Brookview Estates Street Reconstructions City of Ramsey Project No. 19-02 7