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Mr. Mike Higgins 3 December 5, 1991 <br /> Soil stockpile samples were analyzed by the same methods as the original pit sample. <br /> Analytical results revealed the presence of oil and grease at 195 ppm, diesel at 1.6 ppm and <br /> several metals (vanadium, copper and barium) at concentrations slightly greater than Title 22 <br /> STLC values. <br /> Tables 1 and 2 list all analytical results and attached sketches depict ep sampling locations. <br /> Copies of all analytical reports and chain of custody forms are included in Attachment 1.0. <br /> Recommendations _ <br /> ' IT recommends backfilling of the oil/water separator pit with no further action required, based <br /> on the following: <br /> - no product staining or odor were encountered upon separator removal, thereby <br /> indicating areally limited impact, <br /> - oil and grease is non-volatile and highly viscus, therefore it is unlikely that <br /> further migration will occur, <br /> ' - vertical oil and grease concentrations decreased to slightly above detectable <br /> limits following over excavation efforts, <br /> - a lean clay of low permeability was encountered in the excavation bottom, <br /> - groundwater is located at a minimum of 36 feet below the excavation floor, <br /> and <br /> - virtually all metal concentrations encountered in the excavation were below <br /> Title 22 STLC values (with the exception of cadmium found at 1.8 ppm in the <br /> ' original excavation bottom sample; however, the soil in that location was over <br /> excavated. <br /> Upon your approval, the excavation will be backfilled and the site will be repaved. If there <br /> are any questions or comments, please contact me at (510) 372-9100. <br /> Sincerely, 26& <br /> Sydney Mills <br /> Project Manager <br /> SM:mr <br /> 1 <br />