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January 7, 1993 Working To Restore Nature <br /> ARCO Station No 760, Lodi, California <br /> v <br /> CONCLUSIONS <br /> TPHg, kerosene and unspeciated petroleum hydrocarbons have been detected at locations <br /> and depths at and leading away from the former waste oil tank The test method used by <br /> Sequoia Analytical to analyze samples for the presence of diesel fuel can identify <br /> hydrocarbon compounds from C8 - CM A review of all TPHd chromatograms by Sequoia <br /> Analytical indicates that the compounds identified by this test method are in the gasoline <br /> and kerosene (C8- C16) range Therefore, the unspeciated petroleum hydrocarbons detected <br /> by gravimetric analysis (SM 5520) appear to be in the carbon range of CM and higher The <br /> petroleum compounds identified in the vicinity of the former waste oil tank appear to be <br /> a mixture of gasoline, kerosene and high molecular weight petroleum <br /> Data indicates that the vertical extent of gasoline hydrocarbons has been determined at each <br /> drill site On the basis of this and previous investigations, the lateral extent of petroleum <br /> hydrocarbons have not been delineated In the following directions from the former waste <br /> oil tank 1) to the west of B-14, 2) to the north of B-14, 3) to the east of B-18 <br /> Because gasoline and kerosene hydrocarbons were not detected in samples below 36 feet / <br /> • bsg in most soil borings, and attenuate before ground water was encountered, ground water L/ <br /> beneath the site probably has not been affected by gasoline and diesel hydrocarbons <br /> RECOMMENDATIONS <br /> We recommend additional assessment of soil at locations north and west of the station <br /> building and in the northeast cornor of the site to further delineate the lateral extent of <br /> petroleum hydrocarbons. We recommend that the following addendum work plan be <br /> submitted to the appropriate agencies for review and approval <br /> ADDENDUM TO WORK PLAN <br /> At the request of ARCO, RESNA will conduct an additional investigation at the site to <br /> delineate residual hydrocarbons in soil and install additional vapor-extraction wells (if <br /> warranted). Work will be performed according to this addendum to our Work Plan No <br /> 38048-3W (Applied GeoSystems, April 23, 1990) We propose the following work <br /> o Obtain permits from San Joaquin County Public Health Services- Environmental <br /> Health Division (SJCPHS-EHD) to drill borings and install vapor-extraction wells <br /> onsite. <br /> 0 082Occar <br /> 380x8-7 4 <br />