SITE HISTORY - Laserfiche WebLink

Home Browse Search

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