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f. i a groundwater extraction system began operating to assist in controlling migration and enhancing ( vapor extraction. The soil vapor system was augmented in 1994 by a groundwater oxygenation system. The systems have been shut down and soil confirmation samples were collected in 1996. Additional information and previous environmental data are summarized in the Preliminary Site Closure Summary for Former Shell Service Station 141 North EI Dorado Street in Appendix E. Soil and' groundwater may have been impacted from other historical uses at the site (e.g., transportation and storage facilities). It is unknown whether the wood piers possibly treated with pentachlorophenol and creosote have leached into the sediments of the Stockton Channel. 2.5 Regulatory Involvement As part of the EPA-funded Brownfields grant awarded to the City of Stockton, the scope of this field investigation is limited to collecting soil samples, groundwater samples, sediment samples, and wood piling samples at locations on and beneath the site. The Weber Block site is not listed on the Comprehensive Environmental Response,Compensation,and Liability Information System (CERCLIS) or the Resource Conservation and Recovery Information System (RCRIS). A lead agency has not been selected for the Weber Block site at this time. 'DTSC has been asked to review this Sampling and Analysis Plan under a Voluntary Cleanup Agreement-between DTSC , and the Stockton Redevelopment Agency in anticipation of additional removal action or remedial activities that may be conducted at the site. PHS/EHD is .currently overseeing the investigation conducted for the former Shell service station. The oversight is'limited to the northeast portion of the Weber Block Site. No investigations have been conducted on other portions of the Weber Block site. 3.0 SAMPLING RECOMMENDATIONS As shown in Figure 3-1, soil sampling will be conducted at eight locations on Weber Block. All proposed sampling locations were discussed with Mr. Barry Padilla, DTSC, Mr. Wally Woo, ' EPA, and Mr. Tom Mix, EPA, on October 9, 1997. No samples,will be collected in the vicinity • of the former service station. The sampling locations, sample type (discrete subsurface), and analytical methods were determined based on the locations of the potential storage of hazardous . substances associated with the freight sheds, wharfs, and structures that formerly occupied the site. Because it is unknown what has been stored in the freight sheds, a full scan of analytes have been recommended by DTSC and EPA for soil. In general, discrete soil samples will be collected at 5 foot intervals to the water table (e.g., 5, 10, 15, 20 below ground surface [bgs]) at locations SBI through SB3 (up to 12 samples) to determine the soil lithology and to possibly attribute any groundwater contamination to onsite soil sources. If sampler notes soil staining, or unusual odors during coring, the sampler will submit the sleeve closest to the observed contamination. The approximate sample depth shall be noted. Discrete soil samples will be collected between 2 and 2.5 feet bgs and between 5.5 and 6 feet bgs at SB5 through S139 (10 samples). Based on discussions with EPA and DTSC, these sampling depths were selected to determine whether there is soil contamination from possible spills in the vicinity of the former f storage areas, freight sheds, and wharf(see Figure 3-1). Access onto the restricted site has been nA1362I0198SAPlwebsap2.wp5 WEBER BLOCK (Area 9) Sampling and Analysis Plan D Page 5