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(YVAT conducted in conjunction with this closure and the UST was reported to have never contained a hazardous substance. During a May 1998 site visit conducted by ATC, a relatively large oil surface stain was observed on the asphalt surface at the eastern portion of the site. This stain appears to be associated with a spill from a piece of machinery temporarily stored on-site. The estimated volume of the original surface spill is 5 to 10 gallons. The cleanup of the spill was initiated however not completed, as indicted by oil saturated absorbing material observed remaining on the asphalt. It is our understanding that this absorbent has since been collected and the spill mitigated. On November 18, 1998, ATC performed groundwater monitoring and sampling at the subject site. Following the collection of groundwater level measurements in all on-site monitoring wells, ATC collected water samples from monitoring wells MMI, located in the upgradient direction, and from on-site monitoring well MW6, located in the downgradient direction, to determine any site contribution of chlorinated solvents. Additionally, a water sample was collected from well MW4 located near the wastewater treatment system. SCOPE OF WORK- METHODOLOGY In brief, the scope of work includes the following: performing a soil gas survey to document current subsurface conditions beneath the site; soil sampling under each end of a 14,960-gallon underground storage tank (UST) which was filled in-place; and assessing soil beneath a surface stain for the presence of PCBs. All work described in this proposal will be performed under the direction of a California Registered Professional Engineer. Completed soil boring permit applications and associated fees are included in Attachment 2. A site specific Health and Safety Plan is included in Attachment 3. Soil Gas Survey ATC will perform a soil gas survey of the site's suspect areas including the existing and former water treatment compounds. Direct push technology will be employed to advance soil gas probes to desired depths where soil gas will be extracted and sampled. It is anticipated soil gas samples will L1; collected at depths of approximately 7 to 14 feet below ground surface (bgs). At minimum, one soil gas sample will be collected from each boring, however, one additional sample may be collected from selected locations. The soil gas survey will include the collection of up to a total of 14 soil gas samples. Following sample collection, each open bore hole will be grouted to the surface with neat cement. The gas samples will be forwarded to a State-certified laboratory for the analysis of halogenated and aromatic volatile organic compounds utilizing EPA methods 8010/8020 WA16962\REP0RTS\W0RK_PLN.D0C 5