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June 30, 1995 two <br /> Page 9 <br /> 3. The secondary water quality goal for gasoline should be S ppb; <br /> typical detection is 50 ppb. <br /> In regards to utilizing 5 ppb as a secondary water quality goal for <br /> gasoline at the site, Marshack used a 1953 study by Melpolder <br /> (Melpolder, F., et al., 1953, "Mass Spectrometer Determination of <br /> Volatile Contaminants in Water", Analytical Chemistry, Vol. 25 No. <br /> 10 pp 1453-1456) for selecting a concentration for taste and odor <br /> threshold of gasoline in water. It is PACIFIC's opinion that the <br /> concentration listed by Marshack has no merit for use as a regulatory <br /> cleanup goal for the reasons listed below: <br /> • The criteria used to formulate this concentration'were not scientifi- <br /> cally based. The focus of the study was not taste-and-odor <br /> threshold, and the 5 ppb value was provided as hearsay without <br /> supporting data or description of methodology used; <br /> • The Melpolder article referenced by Marshack did not follow taste <br /> and odor threshold testing methodology established by the API <br /> which is suggested for a valid determination. Taste and odor <br /> threshold testing criteria recommended by API are: (1) odorants <br /> are presented to panelists in an ascending concentration series, <br /> (2) the maximum concentration interval between stimuli <br /> presentations do not exceed a factor of three, and (3) the panel <br /> used for threshold determination contains more than five individual <br /> judges. The study referenced did not appear to follow any of these <br /> criteria. <br /> • Regional Water Quality Control Board (RWQCB) - Central Coast <br /> Region and Santa Clara Valley Water District have recognized that <br /> the 5 ppb cleanup goal is unreasonable and have established higher <br /> TPH-g cleanup goals for their oversight areas (1,000 and 500 ppb, <br /> respectively). <br /> PACIFIC is in concurrence that the typical detection limit for TPH-g is <br /> 50 ppb. <br /> 4. The chlorinated plume investigation and subsequent remediation <br /> does not effect ►tater quality goals at the site associated with petro- <br /> leum hydrocarbons. <br /> 32013570CAPLET.DOC.doe <br />