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(C) 1989 BIO NATIONAL CORPORATION <br /> 2 BACKGROUND OF SITE CHARACTERMATION <br /> 2.1 Two groundwater monitoring wells were installed at points directly <br /> through as former tank sites into the aquifer. <br /> 2.1.1 The groundwater under Site #1 was impacted with a significant <br /> layer of hydrocarbon contamination. <br /> -. 2.1.2 Site #2 indicated slight solvent contamination, probably from paint <br /> shop operations, and not the waste oil collection operation being <br /> tested for. <br /> 2.7..3 Soil samples, drawn every five feet, through a hollow stem auger, <br /> indicated contamination above action level in a significant, but <br /> indeterminate, portion of the soil, <br /> 2.2 Two rdditional groundwater monitoring wells were installed in outlying <br /> locations north and east of the known contamination. <br /> These were shown to be negative, with r? evident contamination of soil <br /> or water. <br /> 2.3 The site characterization work to this point did not delineate the full <br /> _F extent of the soil or groundwater contaminat�Dn. <br /> 2.3.1 The groundwater gradient was determined to be from northeast to <br /> southwest, instead of the southwest to northeast direction shown in <br /> M Regional Water Quality Control maps. This seems to be a result of <br /> the dry years causing a change in net flow b3tween the ship <br /> channel to the north and the giver to the south. <br /> This finding in-dicated that further monitoring wells and soil <br /> borings would be required to accurately define the plume. Prior to <br /> facing the expense of this procedure, it was decided to perform a <br /> soil gas analysis on the site to determine the extent of plume <br /> movement, and mora accurately set the sites for additional <br /> monitoring wells. <br /> Based on the soil gas finding's, we anticipate a more cogent <br /> placement of monitoring wells and soil samples. <br /> 2.3.2 To complete the site characterization program, the soil gas report <br /> and verification borings .;need to be completed to verify the extent <br /> of both soil and groundwater contamination. <br /> u We 'have relied on the expertisF) in geology and hydrology of Dames <br /> & Moore, Sacramento office, for a comprehensive site analysis. <br /> Once these parameters are established, the treatment programs will <br /> be finalized. <br /> 2 HOLT805 <br />