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6633 Pacific Ave <br /> Page 2 <br /> 2.0 Conceptual Site Model <br /> Physical Characteristics <br /> The CAP indicated that there were three known fuel cases that were located; <br /> however, these cases were not specifically identified. Please identify the cases which <br /> were referenced. <br /> A parking lot is not located to the west of the facility, but rather a series of <br /> businesses. <br /> The December 1986 tank removal did not include sampling of the piping which <br /> presumably was removed. There is not documentation to support the presumption <br /> that the piping was removed. While the replacement tanks were double contained, <br /> the piping was not. In 1991, PHS/EHD received a piping removal and replacement <br /> plan which was approved on July 31, 1991. Please note that this plan was never <br /> implemented. <br /> Primary Source <br /> The CAP indicated that the available data suggested that the primary sources of <br /> petroleum hydrocarbons were the former product storage and piping facilities. <br /> Unfortunately, PHS/EHD does not concur with this conclusion because the <br /> concentrations detected during the 1986 tank removal do not correlate with the level <br /> of groundwater contamination which has been evidenced and there were no soil <br /> samples collected from beneath the piping which was associated with the operation <br /> of the former underground storage tanks. <br /> The CAP included a brief discussion of a relatively recent source of hydrocarbons but <br /> does not provide sufficient information to show that the product delivery system is <br /> no longer contributing to the contamination of the site. <br /> Secondary Source <br /> The CAP failed to include residual soil contamination as a secondary source of <br /> contamination. The CAP did include capillary fringe soils and continuing <br /> groundwater contamination. <br /> The discussion of the vadose zone of impacted soil stated that the hydrocarbons were <br /> limited to soils directly underlying the former USTs and were not laterally or <br /> vertically continuous. It is true that the contamination did not extend to MW1 and <br /> MW3; however, there is no evidence to suggest that the vertical or horizontal extent <br /> of the contamination associated with the former underground storage tanks has been <br /> determined. <br />