SITE INFORMATION AND CORRESPONDENCE

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Se tt�Bd: -BASELINE; 510 420 1707; Nov-1.2-99 9:02; Page 516 i RECOMMENDATIONS � Based on the findings of the PEA, the following future actions are recommended: • No additional groundwater or soil investigations are recommended at this time to fill any data gaps. Several environmental investigations have taken place at the site since the early 1990s, which sufficiently Identify and delineate subsurface contamination. • The City of Stockton should implement a deed restriction at the Weber Black property to prevent future residential site use. The deed restriction should include restrictions on the use of shallow groundwater underlying the site for ingestion and bathing�showering. The deed restriction should also consider restrictions on future utility work at the Weber Block property for the protection of utility workers corning into contact with any groundwater and/or contaminated soil underlying the sitC. • The City of Stockton should encourage ARCO to quickly and efficiently begin groundwater remedial activities for aromatic hydrocarbons and chlorinated compounds at the former ARCO property. This site is upgradient of the Weber Block property and is now owned by the City of Stockton. The property purchase agreement included remediation of any groundwater plurnes by ARCO,extending off this property,under the direction of a regulatory agency. Groundwater samples collected at the Weber Block property indicate that contamination from this off-site property is migrating onto the Weber Block site and contamination of some compounds not associated with land uses at the Weber Block property has been increasing over time(i.e.,methyl tert butyl ether) adversely impacting groundwater quality. Remediation of groundwater at the ARCO property may require existing groundwater monitoring wells (or replacement wells) at the Weber Block property to be periodically monitored to assess the efficiency of the chosen remedial action. • Benzo(a) pyrene, a semi-volatile polynuclear aromatic hydrocarbon(PNA),was the greatest risk contributor to the exposure pathway of incidental ingestion and dermal contact with sail. Other PN As,including benzo(a)anthracene,benzo(b)fluoranthene,and benzo(k)fluoranthene, also collectively contributed to the risk estimate for soil ingestion and dermal contact. .This risk estimate was calculated assuming no capping or planned excavation at the site to prevent exposures, an extremely conservative assumption. Under the proposed development of the property as a water square,all of the locations where FNAs were reported above the laboratory reporting limit in soil samples are located-in areas proposed for raised landscape planters; paved areas (with a minimal distance frorn'the sample(s) to the paving of approximately 3 feet), landscaping with imported soil to support growth,.or are in areas that will undergo complete excavation to at least the depth that.the, sample(s) was collected. Paving, raised landscape planters with clean imported"soil, landscaping with clean imported soil, and/or excavation of these areas, as proposed for the Weber Block redevelopment project, ate effective means of reducing and/or eliminating this potential.exposure pathway,and therefore the resulting risk. • The City of Stockton should request Sari Joaquin County Public Health, Services, Environmental Health Division, to issue a letter of no further action for the Weber Blau: 97 369ctk.pe2.wpd-l 119;99 34