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Environmental <br /> Mr Harlin Knoll Resources <br /> 14 August 1998 Management <br /> Page 4 <br /> Subsurface Conditions <br /> Boring B-5 was drilled in the location of the former UST and through the <br />' backfill of the tank removal excavation Based on the boring log, the soil <br /> lithology of boring B-5 consisted of artificial fill from ground surface to <br /> 10 feet bgs, silty clay from 10 to 25 feet bgs, and silty sand from 25 to 41 <br /> feet bgs The sand transitioned to clay near 41 feet bgs and the borehole <br /> was terminated at 415 feet bgs The initial depth to water in boring B-5 <br />' was 39 5 feet bgs, which stabilized at a depth of 38 6 feet bgs <br /> Boring B-6, located 15 feet northeast of boring B-5, was drilled within the <br /> asphalt-paved area Soil lithology at boring B-6 consisted of clayey silt <br /> from below the asphalt to a depth of 40 feet bgs and silty clay from 40 to <br /> 415 feet bgs The initial depth to water in boring B-6 was 38 3 feet bgs, <br />' which stabilized at a depth of 37 9 feet bgs <br /> According to San Joaquin County, based on previous investigations in <br /> the vicinity, ground water typically occurs at depths between 40 and <br /> 50 feet bgs with a northeast gradient The ground water flow direction at <br />' this site was not confirmed during this investigation <br />' SoiI Borings <br />' Borings B-5 and B-6 were drilled using a truck-mounted hollow-stern <br /> auger drilling rag, utilizing 8-inch outer-diameters augers A 2-inch <br /> diameter split-spoon sampler with an 18-inch long core barrel was used <br /> to collect soil samples in brass liners for lithologic description and <br /> chemical analysis Soil samples were monitored for volatile organic <br /> vapors using a photo ionizing detector (PID), then described by an ERM <br /> geologist according to the Unified Soil Classification System The results <br /> of the PID monitoring, a visual description of the soil, and blow counts <br />' were recorded on boring logs Soil borings were advanced until ground <br /> water was encountered at approximately 38 feet bgs Soil borings were <br /> abandoned by falling the borehole with a bentonite/cement grout <br /> mixture <br /> The sampling strategy involved collecting soil samples from borings <br /> located within and downgradient of the former UST location Although <br />