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r Mr.Nuel Henderson �.. .. Re: 102 S. Wilson Way—Petition for Closure Page 6 Previous Action by the SWRCB In 2004, the State Water Resources Control Board (SWRCB)considered a petition by Chevron with regard to a site located in Santa Cruz County(WQ Order 2004-0005, attached). The SWRCB unanimously supported the assertion that it was unreasonable to require Chevron to conduct further investigation or remediation of the site in question. The SWRCB stated that the Regional Board did not provide substantial evidence indicating that contamination originated from the Chevron site. Although this WQ Order was not designated precedential due to the unique facts of the case,the facts presented in the Chevron petition strongly correlate to the facts relevant to the 102 S. Wilson Way site. Overview of WQ Order 2004-0005 Chevron operated a service station on the site in question from 1953 to 1972,with the underground storage tank system being removed in 1973. Another former gasoline retail site is located across the street. After investigations,the Central Coast Regional Board staff concluded that two separate plumes of petroleum hydrocarbon contamination emanated from the sites of both former service stations. Evidence submitted by Chevron showed only one plume with contaminants migrating from the other site. The Regional Board staff reiterated its conclusion that evidence showed two separate sources of contamination. Chevron appealed to the SWRCB contending that the evidence shows a single plume of petroleum hydrocarbon contamination spreading from the other site,and argued that it should not be held responsible for the continuing investigation and cleanup at the site of its former service station. The SWRCB agreed with Chevron. The SWRCB staff conducted a technical analysis of the evidence,concluding the following: Water samples collected that year [1995] from the basement sump on the former Chevron site showed contaminant levels at very low to non-detect values. In 1998,by contrast, water samples collected when the sump flooded showed concentrations of TPH-g and BTEX from 1,000 to 10,000 times greater than the values detected three years earlier. The low concentrations of BTEX in the sump water in 1995, followed by high concentrations in 1998,without any new source at the former Chevron site, provide direct evidence that gasoline and groundwater with high concentrations of gasoline constituents have migrated from the Opal Cliffs site [the site across the street] onto Chevron's site. The significant increase in contaminant levels from 1995 to 1998 is much more consistent with operation of the sump pump drawing in contaminants from the Opal Cliffs plume than from lingering contamination at the Chevron site,which had not operated for more than twenty five years.