ARCHIVED REPORTS XR0011054 - Laserfiche WebLink

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to TABLE 5 for a summary of those results. The high levels of TPH-G detected in the water samples were not expected, since those in the soil samples were very low. It was mentioned by ESE, Inc. that the known groundwater contamina- tion site diagonally across the street, (Exxon Gaso, ) may be the source. More recent monitoring work at both the Morita & Gaso sites supports that analysis. The groundwater contamination problem is a separate issue from the subject of this report, and will be addressed in other documents. Because of the very low levels of contamination encountered in soil samples below 20' , it is not considered feasible to attempt insitu remediation. Removal of the contaminated spoil which was returned to the hole, and additional excavation to remove any remaining hydrocarbon components was agreed by all parties to be the best approach. On February 12, 1993, Jim Thorpe Oil , Inc. , (JTO, ) submitted a workplan to the San Joaquin County EHD for accomplishing that task. A copy of that workplan is attached as • EXHIBIT E. S �Y OFDOI� UNDER WORKPLAN SURMITTEED 2/12/1 93: Work began on March 31, 1993, by JTO personel using a 690C exca- vator and a 966D front loader. Concrete was removed from the area occupied by the pump island, and placed to one side for later removal. Heavy gauge black plastic was placed in an area at the southeast end of the property, and also at the north end adjacent to the existing building. Clean soil was to be placed on the north side, and contaminated soil in the area south of the building. Under the direction of Wm. Hunter, RG, from Wm. J. Hunter & Associates, (WJH, ) the excavator was located on the south side of the existing excavation, and began by removing the top 6' of fill , which was not contaminated. The soil was placed on the asphalt adjacent to the hole, and then picked up by the front loader and placed on plastic at the north end of the property. Below a depth of about 6' , a definite petroleum odor was noted, although no visible staining or discoloration was evident. The contaminated spoil was moved by the front loader and placed on Plastic at the southeast end of the lot. The removed spoil consisted primarily of tan to brown sandy loam, with occassional layers of "hardpan. " Visual observation indicated that the con- tamination was highest near the end of the piping trench. A dark gray layer of clay, (9"" to 12" thick, ) at a depth of about 10-12' 4