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GEOTHASE <br /> ENVIRONMENTA <br /> Yen <br /> DEC 0 6 2006 <br /> Date: 12/4/2006 ENVIRONI4E(V <br /> TN <br /> PERM/T/SE,gVICES <br /> GPE Project No.: 518.2 <br /> i <br /> Mr. Harlan Knoll <br /> San Joaquin County EHD _ <br /> 304 E. Weber Avenue, 3"Floor <br /> Stockton, CA 95202 <br /> Re: Diesel Spoil Pile <br /> Nelson Ready Mix,2059 Navy Drive,Stockton,CA <br /> Dear Mr. Knoll: <br /> As you know, an estimated 150 cubic yards of diesel-impacted spoil material remain on the <br /> site from the over-excavation of the former tank pit. On October 20, 2006, a suite of three <br /> 4-point composite samples of the soil was collected from the soil, and the.samples were <br /> tested for BTEX and TPH-G. Copies of the laboratory data sheets are attached. No BTEX <br /> constituents were detected in any of the samples. Diesel-range petroleum hydrocarbons <br /> were detected as follows. <br /> Sample I.D. TPH-D <br /> C-1 ND<5 <br /> C-2 110 <br /> C-3 90 <br /> MDL 5 mg/Kg.g <br /> The average diesel concentration detected in these samples is 68.ppm; assuming the value <br /> of C-1 is 5 ppm. Referring to the leaching potential table in the old LUFT manual <br /> (attached), the leaching potential score'for this site is 39, which corresponds to an <br /> allowable residual soil concentration of 100 ppm. This result suggests that the residual <br /> spoil dirt on the site does not pose an environmental threat to the groundwater. ' <br /> Given the industrial use of the site, the low diesel concentration in the soil would also <br /> appear to pose a minimal health hazard to workers. Assuming a conversion factor of 1.6 <br /> 2937 Veneman Ave.,#B240 Geo-Phase Environmental Inc. Phone: (209)569-0293 <br /> Modesto, Ca 95356 Fax: (209)569-0295 <br /> i <br />