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500-feet for the majority of the project, and at 100-feet for areas of higher concern, including areas with known groundwater issues and in areas with adjacent wetlands. The borings terminated at depths ranging from approximately 10.5 to 18.5 feet below the top of pavement. The locations of the borings are shown in the Soil Boring Location Map in NTI's report, included in Appendix D. The soil borings generally indicate the existing bituminous pavement thickness ranges from approximately 1.5 to 8.0 inches at the boring locations. Apparent aggregate base thickness ranges from approximately 3.0 to 24.0 inches. Apparent previously placed fill soils generally consisting of poorly graded sand, poorly graded sand with silt, silty sand, and sandy lean clay were encountered to depths ranging from approximately 2.0 to 7.0 feet below the top of pavement. Organic materials and bituminous pieces were occasionally encountered within the fill materials. The apparent previously placed fill was not observed at Boring SB-38 and Boring SB-5 terminated in fill materials at a depth of approximately 10.5 feet below the top of pavement. Native glacial deposit soils consisting of poorly graded sand to poorly graded sand with gravel, poorly graded sand with silt to poorly graded sand with silt with gravel, silt sand, and clayey sand were observed extending to the boring termination depths. Swamp deposit soils were observed at Borings SB-23, SB-24, SB-35, SB-37, SB-39 through SB- 44 and SB-46 through SB-49 consist of silty sand, poorly graded sand, poorly graded sand with silt, sandy silt, and peat. Organic contents of selected samples ranged from 2.1 to 53.7 percent with moisture contents ranging from 26 to 236 percent. Groundwater was observed in 35 of the 57 boreholes at the time of drilling. The groundwater depths, which can fluctuate seasonally, ranged from approximately 2.5 to 11.5 feet below the top of pavement. The lack of observed groundwater in the remaining borings is likely due to the short duration for which the borehole remained open combined with the varying site elevations. Additionally the on -site silt laden soils have the potential to be impervious and conducive to the development of zones of perched water at varying elevations and locations across the project area. 3.2. b R-Value NTI estimated that a properly prepared subgrade would have an average stabilometer R-value based on soil types as referenced below: • Poorly graded sand (SP) — R-value of 50 • Poorly graded sand with silt (SP-SM) — R-value of 40 • Silty sand (SM) — R-value of 25 City Staff reviewed the boring logs within the Geotechnical Report, and calculated an average R- value of 36 for Variolite Street. This R-value directly affects the support of the pavement section, Feasibility Report Variolite Street Reconstruction City of Ramsey Project No. 20-01 4