Agenda - Council - 10/26/2021 - Laserfiche WebLink

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3.2 Soil Conditions Buried Topsoil Soil boring SB-11 encountered an approximate 2-inch layer of black silty sand directly below the aggregate base or possible aggregate base which appears to be buried topsoil. Buried topsoil or other organic soil were not encountered in the remaining borings. Fill Below the pavement section soil borings SB-04, SB-08, SB-09, SB-10 and SB-13 encountered previously placed Fill that extended to depths ranging from about 4 to 9 feet below the ground surface. The remaining borings did not appear to encounter Fill below the pavement section. The Fill consisted of poorly graded sand, poorly graded sand with silt and silty sand that was brown or dark brown in color. N-Values, shown as blows per foot (bpf) on the boring logs within the previously placed Fill ranged from 5 to 23 bpf. These values indicate the Fill had a loose to medium dense relative density. Native Alluvium Beneath the pavement section or Fill the soil borings encountered native alluvial deposits that extended to the termination depths of the borings. The native alluvial deposits consisted of fine to coarse grained poorly graded sand and fine to coarse grained poorly graded sand with silt that contained varying amounts of gravel. These soils generally correspond to the ASTM Classifications SP and SP-SM, respectively. N-Values within the sands ranged from 3 to 26 bpf. These values indicate the sands had a very loose to medium dense relative density. 3.3 Groundwater Groundwater was encountered in some of the borings while drilling and sampling or after removing the augers form the boreholes at depths ranging from about 8 1/2 to 14 feet below the ground surface corresponding to elevations ranging from about 851 1/2 to 856 feet. The observed water levels are summarized in Table 2. Table 2. Summary of Groundwater Levels Boring Number Ground Surface Elevation (ft) Approximate Depth to Groundwater (ft)* Approximate Groundwater Elevation (ft)* Krypton Court SB-01 874.E NE - Iodine Court SB-02 884.7 NE - SB-03 871.6 NE - Junkite Street SB-04 866.2 12 854 SB-05 864.5 81/2 856 SB-06 870.2 14 856 146th Circle SB-07 876.3 NE - 4