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. Mr. Steve Sasson Project 22794-100.001 August 10, 1998 Page 11 methane in groundwater in the western part of Stockton as factors for taking the well out of service. Thus, generally poor water quality in the site vicinity precludes use for drinking water. — Additional data shows that the groundwater quality is generally poor in the first-encountered water-bearing zone and the secondary MCLS for chloride, TDS, and sulfates are exceeded at the Port of Stockton fuel distribution terminals — Chemrisk prepared a Tier 2 Report for the site in February 1996. Chemrisk evaluated the volatile and semivolatile organic chemicals in site soils. The RBCA results concluded the concentrations are below levels that pose unacceptable risk to workers and to groundwater quality. SSTLs calculated for BTEX and PNA constituents are not exceeded by the maximum detected concentrations for the respective parameters. Since the site is covered with concrete paving, infiltration of surface water is not considered a mechanism for transporting residual petroleum hydrocarbons down to groundwater. In addition, natural attenuation would further reduce any residual concentrations of petroleum hydrocarbons In summary, based on the facts that (1) the bulk of petroleum hydrocarbons has been removed, and (2) infiltration at the site is expected to be minirnal, it appears that any remaining on-site petroleum hydrocarbons are unlikely to adversely impact groundwater. Furthermore, based on subsurface investigations conducted upgradient of the former Safeway UST's and historical land use on and near the property, it appears other sources of groundwater impact are present in the site viciruty Therefore, on behalf of Safeway, EMCON respectfully requests closure of the 1111 Navy Drive, Stockton,project. SAC%N\PJZ\Z794\279410001CS-98\Pwaner8 Emeon Rev 0.8/10/98