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REOU T FOR SITE CLOSURE <br /> Genersi kMiHs Faclry <br /> 2000 Wes[Turner Road <br />• Lodi. Cauforrna <br /> Delta P-plecc No -0-92-708 <br /> Page 4 <br /> At the April 15, 1993 meeting, the County suggested that we present our case for leaving soil m place <br /> with concentrations of TPH as diesel No b over 100 ppm to the Technical Advisory Committee After <br /> consideration. General Mills has decided to proceed with this suggestion To support our case, General <br /> Risk Appraisal analyses were perrormed. <br /> 2.7 Leaching Potential inalvses <br /> The Leaching Potential Analysis, presented in the LUFT Manual was developed to estimate the <br /> concentration of BTEX, TPH as gasoline, and TPH as diesel that can be safely left in soil at a site <br /> without posing a risk to around water quality It is used as a screening methoa to determine whether <br /> additional site analyses are necessary As stated by Odencrantz, at_ al , "This screening table is <br /> incorrectly used throughout Califorma by a wide variety of agencies and private entities to determine TPH <br /> and BTEX cleanup concentrations If it is found during the screening step using Table 2-1 (LUFT <br /> Manuai) that additional detailed analysis are required, the LUFT manual provides a more detailed analysis <br /> that compares "cumulative concentrations" of BTEX to compound-specific tables for determinations of <br /> appropriate cleanup levels. Tnis second, more involved analysis, termed the General Risk Appraisal, is <br /> rarely performed or enforced" <br /> The County is incorrectly applying the screening table to trigger further remediation, winch is clearly not <br /> the intent of the LUFT manual. <br /> 3.0 GENERAL RISK APPRAISAL <br /> Proceeding on the prenuse that the County's Leaching Potential Analysis results are appropriate <br /> (maximum allowable concentration of TPH as diesel Yo b should be 100 ppm), the next step <br /> recommended in the LUFT Manual is either cleanup or additional site analysis such as a General Risk <br /> Appraisal. Delta has performed a General Risk Appraisal as described on pages 36 througa 46 of the <br /> LUFT manual. <br /> The General Risk Appraisal is more sophisticated than the Leaching Potential Analysis. It was developed <br /> 10 to evaluate the risk of o ound water pollution at an underground fuel storage tank site from BTEX <br /> concentrations in soil. Delta performed three analyses: one for toluene, one for ethylbenzene, and one <br /> RpTW6 TA <br />