ARCHIVED REPORTS XR0012678 - Laserfiche WebLink

Home Browse Search

w w IM P MMM A third phase of site investigation was performed by Leedshill- Herkenhoff, Inc. in which eight soil borings and three groundwater monitoring wells were drilled and sampled to determine subsurface conditions at the site (Figure 4). In addition to the gasoline plume, the used-oil tank failed a precision tank test on June 5, 1990. The contents of the used-oil tank were removed and disposed of Off-site. The tank inlets were then capped and the tank has been out of service since that time. Soil samples were collected from both the soil borings and monitoring wells and laboratory analyzed for - benzene, toluene, ethylbenzene, total xylenes (STEX) using EPA method 8020 and total petroleum hydrocarbons (TPH) as gasoline using modified EPA method 8015. Samples collected from near the used-oil tank were also analyzed for TPH as diesel using modified EPA method 8015. Laboratory analyses of soil samples determined that petroleum hydrocarbons are present largely near the center and on the eastern side of the former storage tank excavation. This was confirmed by additional soil sampling -�rformed by RESNA/WaterWork as discussed below. A fourth phase of investigation was conducted by RESNA\WaterWork in April of 1990. RESNA/WaterWork Corporation supervised the drilling of 7 additional soil borings at the site, two of which were converted to groundwater monitoring wells and three of which were converted to vapor extraction wells (Figure 4). one soil boring was located north of the fo=,ar tank pit excavation in Channel Street to help determine the lateral extent of soil contamination north of the site. One soil .. ^ boring was angle drilled beneath the eastern dispenser island to a total depth of approximately 20 feet below grade to determine subsurface conditions beneath the dispenser island. Two borings, one in the northeast corner and one west of the former tank pit excavation, were advanced 15 feet below first groundwater and -- converted to monitoring wells to determine water quality in these areas. Logs of these two wells are contained in Appendix 1. All soil and groundwater samples were sent to state-certified Applied Analytical Environmental Laboratories in Fremont, California. Selected soil samples were laboratory analyzed for BTEX using EPA method 8020 and TPH as gasoline using modified EPA method 8015. Laboratory analyses determined that benzene above method detection limits was detected only in soil samples from borings VP1 and VF3 in concentrations which ranged from 0.008 ppm to 0.076 ppm. Total -- petroleum hydrocarbons as gasoline concentrations were detected only in borings ASBI and VP1 in concentrations which ranged from 2.4 ppm to 33O0 ppm. Table I summarizes laborgtory results from soils. Laboratory reports with chain-of-..ustody documents are presented in Appendix II. Based on the laboratory analyses of__soil__samples-.bg, -both- Leedshill - Herkenhoff and, RESNA; the lateral extent of hydrocarbon impacted soils is restricted to the former storage tank excavation and beneath the eastern dispenser island. The vertical extent .of hydrocarbon impacted soils has been constrained by the shallow water table at approximately 30 feet below grade. A vapor extraction .feasibility test was conducted by RESNA\WaterWork in April 1991 to determine the possibility of vapor extraction as a weber Potnt Property - 475 N208nP791.TLP :;