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Meeting Notes <br /> OEHHA/Unocal <br /> Former PureGro/Brea Facility <br /> March 4, 1998 <br /> Page 2 <br /> Dr. Salinas stated that OEHHA does not have an established policy,but prefers to have most <br /> chemicals included as chemicals of concern, and to use a screening risk assessment approach <br /> to eliminate ones of little to no concern. If such a compound occurs at a place on a site <br /> which is known to have been an area where such contaminants were handled, dispensed, etc. <br /> it might constitute representation of a"hot spot" and should therefore be included in the risk <br /> assessment. If such a compound is present in some definable pattern(a plume, in proximity <br /> to some previous or current source, such as a tank, dispenser, etc.) it should be considered <br /> as well. If, on the other hand, it is isolated from such associations,and confirmatory testing <br /> is negative, it might well be eliminated. <br /> 3. Nick asked if they would require strict adherence to the Preliminary Endangerment <br /> Assessment (PEA) Guidance Manual? <br /> Dr. Salinas stated that the PEA manual was a starting point,but that he does not require strict <br /> adherence to PEA, and that it should be considered as a guideline. <br /> 4. John Rapp asked if Julio had seen solid, defensible, science-based risk assessments approved <br /> by OEHHA, then rejected by the risk manager based upon arbitrary policies (i.e. strict <br /> adherence to the Basin Plan)? <br /> Dr. Salinas replied that in about 90 percent of cases no difficulties had occurred between <br /> OEHHA and the risk manager. <br /> Comment by Eric Chase: Can we therefore infer that in 10 percent of cases Mr. Rapp's <br /> scenario is played out? <br /> 5. Lee Shull asked if probabilistic risk assessment (as compared to deterministic risk <br /> assessment) will be accepted by OEHHA? <br /> Dr. Salinas said yes,that probabilistic risk assessment was good science and he considers it <br /> the wave of the future in risk assessment. Lee Shull agreed with these statements. <br /> 6. Nick asked if OEHHA accepts probabilistic risk assessment, will the risk manager <br /> (RWQCB) also accept it for this project? <br /> Dr. Salinas suggested that both a deterministic and a probabilistic approach be employed, <br /> and that a case be made for the use of one or the other approach. A consensus was reached <br /> by the consultants and the OEHHA personnel that no provision for probabilistic risk <br /> assessment is expressed in the Basin Plan, but Julio pointed out that it is not precluded by <br /> the basin plan either. He also stated that in a probabilistic approach,more than one exposure <br /> scenario would have to be evaluated. <br />