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Sent. By. Rt'VOCS SACRAMENTO; 916 255 3015; Feb-24-99 14:10; Page 5/5 I <br /> 1665 Pacific Avenue -4- 16 February 1999 <br /> Petition Summary and Conclusions Regional Board Respomse <br /> (Pages 12- 14 <br /> b). Additional soil and groundwater monitoring at During January and February 1999,at the request <br /> petitioners site is not necessary. of the San Joaquin County Isocal Oversight <br /> Program,with concurrence from Regional Board <br /> staff,UNOCAL completed deep plume assessment <br /> activities and installed deep monitoring wells. The <br /> results of these activities have not been submitted <br /> for regulatory review and this information must be <br /> reviewed before considering the site for no further <br /> action required. <br /> 7). The level of site cleanup is consistent with the This is a very general statement and is not <br /> maximum benefit to the people of the state. supported by the body of the petition review. <br /> 8). Given the adverse technical and economic No argument for technical and economic <br /> implications statewide if further corrective action infeasibility has been presented. Soil vapor <br /> was required,and minimal benefits,if any,that extraction was effective as a remedial alternative <br /> would be gained by further corrective action,it is during the limited duration of system operation. <br /> not feasible to attain background water quality at The system was shut down when SVE air <br /> the petitioners site. emissions exceeded permitted threshold values. <br /> Continued SVE operation is needed prior to any <br /> determination that it is not feasible to attain <br /> background water quality. <br /> 9). Detectable concentrations of BTEX int shallow This statement implies that remaining <br /> groundwater in contact with the limited residual concentrations of BTEX are close to detection <br /> petroleum hydrocarbons adsorbed to soil particles li` its. This isnot the case.Respective benzene <br /> may remain above MCLS and thus violate the and toluene concentrations up to I.00()pg&(ppb) <br /> Basin Pian objectives in a very localized,small and 12,000µSIL remain in groundwater below the <br /> volume of surrounding groundwater for decades. site. I agree that contaminant concentrations in <br /> groundwater below the site and offsite do and will <br /> violate Basin Plan objectives for a substantial <br /> period of time(an estimatc of the duration has not <br /> been presented). The contaminated subsurface <br /> volume and the residual mass of petroleum <br /> hydrocarbons in soil and groundwater Inas not been <br /> provided,therefore the statement("...limited <br /> residteal petroleum hydrocarbons...")is not E <br /> appropriate. <br /> I <br /> f <br /> I <br /> _ _ l <br />