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Ms Tammy Hodge CAMBRIA <br /> November 1, 1996 <br /> RECOMMENDATIONS <br /> The primary objective of Cambna's review was to assess whether the site can be considered a low-nsk ground <br /> water site' A low-risk ground water site has the following general characteristics <br /> • The leak has stopped and the hydrocarbon source has been removed, <br /> • The site is adequately characterized, <br /> • Ground water is less than 50 ft deep, <br /> • The hydrocarbon plume is stable or decreasing, <br /> • No water wells or other sensitive receptors are likely to be impacted, <br /> • No preferential pathways exist at the site, <br /> • The site presents no significant risk to human health, <br /> • The site presents no significant risk to the environment <br />. Site specific characteristics relevant to each of the RWQCB characteristics are discussed below <br /> The Leak Has Stopped and the Hydrocarbon Source Removed The tanks and piping have been removed, j <br /> no liquid-phase hydrocarbons have ever been detected at the site and the hydrocarbon concentrations detected <br /> in soil do not suggest the presence of liquid-phase hydrocarbons in soil In addition, the clayey site soils to 10 <br /> ft depth prevent leaching of hydrocarbons from the vadose zone Therefore, there does not appear to be <br /> hydrocarbon source remaining in soil that could result in increasing hydrocarbon concentrations in ground <br /> water This conclusion is supported by the decreasing hydrocarbon concentrations in ground water which <br /> indicate that no significant source is present <br /> Site Characterizatton The extent of hydrocarbons in soil and ground water has been adequately defined by <br /> the eight soil borings (five of these were converted to monitoring wells) and five monitoring wells As <br /> discussed earlier,hydrocarbons in soil are confined to a small area at about 10 ft depth adjacent to the eastern <br /> wall of the former gasoline tank pit <br /> ' California Regional Water Quality Control Board-Central Valley Region Revised Draft Recommendation for Low Risk <br />• Site Classification 6 pages July 1996 <br /> I <br /> 7 <br />