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'' 71W" I <br /> �ad a <br /> ,��',-.- y'�� +'�.v.:9' .a,a ar �'liw . r�.�.c� r .`S`t �a� � '"�, "w.*°'i ;�"' oe':e .4, e �} -•� ,k:' -W i'�.a;,t.. SJ _-,.,�r <br /> 1 ' <br /> Chevron/South Center 4 <br /> September, 1990 <br /> hydrocarbons in excess of 50 parts per million (ppm) in four soil <br /> samples (two from the fuel-tank pit, one from the waste-oil tank <br /> pit, and one from the southern end of the eastern pump island) . <br /> Based on these findings, Groundwater Technology, Inc. conducted <br /> additional scil excavation in these areas. Subsequent sampling <br /> of the bases of the deepened tank-excavation pits showed levels <br /> of adsorbed hydrocarbons below 5o ppm- Excavation in the <br /> T vicinity of the pump island could only proceed to a depth of <br /> 6-feet below grade due to the presence of building rubble in the <br /> subsurface. Samples taken from this excavation showed levels of <br /> adsorbed gasoline hydrocarbons in excess of loo ppm. <br /> The excavated soils were treated on site and disposed of at <br /> „,. the West Contra Costa Sanitary Landfill in Richmond, California. <br /> The site was reconditioned and is in operation as a Chevron <br /> Service Station. <br /> WORK STEPS <br /> The following work steps are proposed: <br /> Rwi <br /> o Install four groundwater-monitoring wells on-site. <br /> is <br /> o Monitor and sample the wells to establish local <br /> gradient and to assess the possible impact to <br /> groundwater from gasoline and waste-oil hydrocarbons. <br /> -. o Issue a report on the results and findings of this <br /> R, assessment. This report will include recommendations <br /> for any additional assessment and/or remediation for <br /> his site. <br /> GR{)L'tiIIN'ATF.R <br /> Trch.Noi omti:Inc. <br /> t <br />