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Mr.Nuel Henderson Re: 102 S. Wilson Way—Petition for Closure Page 7 Subsequent investigation showed degraded diesel-range hydrocarbons in shallow soil samples. At lower soil levels(depths of 10 feet below ground surface and greater), however, samples from the Chevron site reflected a relatively fresh gasoline constituent profile inconsistent with a pre-1972 release. With respect to the soil contaminants,the SWRCB concludes the following: The Chevron station may have had minor surface releases during its operations... However, there is sufficient evidence available in the record to determine that the magnitude of any possible releases prior to 1972 were minor in nature, did not materially contribute to the plume,and would not warrant further investigation or remediation. Under these circumstances, we are unable to conclude that the Regional Board appropriately named Chevron as a party responsible for the ongoing investigation and remediation of a plume originating off-site. With regard to the Regional Board assigning Chevron responsibility for ongoing monitoring activities,the decision includes the following: The letter order under petition was issued pursuant to the Regional Board's authority under Water Code section 13267. That section broadly authorizes the regional water quality control boards to require persons who discharge, have discharged, or are"suspected of having discharged or discharging"waste that could affect water quality to furnish technical or monitoring program reports. When acting under this broad authority, regional boards must identify the evidence that supports requiring that person to provide the reports... In this case, however,evidence gathered pursuant to the earlier investigations does not support continuing requirements that Chevron investigate and remediate petroleum hydrocarbon contamination at its former site. Applicability of Facts The similarities between the two cases are profound. There are only two substantive differences between the facts presented by Chevron and the facts relevant to the site at 102 S. Wilson Way. The first difference is the level of contamination present at the initial investigation. Where the Chevron site showed contaminant levels at very low to non-detectable values,the investigation of the 102 S. Wilson Way site showed a higher concentration of many contaminants. A critical fact,however, is that even at the initial monitoring of the 102 S. Wilson Way site there was evidence of a gasoline constituent profile that is inconsistent with a pre-1977 release. This data should have been factored into the County's initial determination of responsibility. The second primary difference is the level of monitoring and remediation undertaken by the previous owner of the underground storage tanks. Chevron was issued a letter order from the Central Coast Regional Water Quality Control Board on November 9, 2000 and