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• No state or federal water quality goal has been developed for naphthalene, therefore the analytical detection limit was used, • The environmental attenuation factors for the Site are above average because of the low infiltration asphalt paved surface, the fine-textured soils, and the depth to groundwater of 56 feet bgs, • The environmental attenuation factor for TPH-d was estimated to be above average because of its low water solubility (high LF), and the sharp reduction in TPH-d concentration with depth, • The environmental attenuation factors for napthalene and other semivolatile constituents reported in soils were estimated to be average because of their moderate water solubility, and • For total designated level calculations, the lower (more conservative) value for the LF was used ► Despite the use of conservative assumptions in the DLM evaluation, the residual TPH in soils does not exceed the total or soluble designated levels ► Based on this DLM evaluation, none of the reported site constituents present in soils present a potential to impact groundwater . Groundwater Chemistry • No detections for TPH-d or BTXE were reported for DMW-1, DMW-2, DMW-3, or the newly installed DMW-5, • A reported detection of 0 18 mg/1 TPH-d in DMW-4 on 5/2195 was resampled on 5/26/95, and re-analysis of the groundwater sample reported a non-detectable concentration of TPH-d (c 0 05 mg/1), • Analysis of a groundwater sample from DMW-5 for volatile halogenated hydrocarbons reported detections of carbon tetrachloride, chloroform and 1,2- dichloroethane varying from 0 00065 to 0 04 mg/l, No. Given the number of potential off-site sources of volatile halogenated organic compounds in the vicinity of the site, off-site sources of these constituents should be evaluated Groundwater Level • Despite record precipitation levels in the Stockton area in 1994/95, groundwater levels only rose from approximately 61 feet bgs (5/94) to 56 feet bgs (5/95), still 20 feet below the high groundwater level mark of 35 feet bgs in 1987, ► Recent above-average precipitation in 1992/93 and 1994/95 has not compensated for the groundwater overdraft SAC156 14 14 DAMES &MOORE