ARCHIVED REPORTS XR0012588 - Laserfiche WebLink

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1.0 BACKGROUND .- The subject site is located in San Joaquin County, at 1403 Country Club Drive, Stockton, California (Figure 1). Hydrocarbons have been determined present in both soil and groundwater at this facility (Section 1.3). This work plan is being submitted in order to satisfy San Joaquie'Cuunty requirements for: • A Work Plan to define the extent of groundwater contamination. - A Work Plan to deal with soil contamination, prior to backfilling - either of the former UST excavations. i This work is being conducted with oversight by the San Joaquin County Public Health Services Site MitigationUnit. : A Tarek Closure Report is currently being prepared -which will discuss tank removal, associated soli sampling and - results; and characterization and disposal of excavated soils. That report +1111 be provided to both the County UST and Site Mitigation Units. SITE HISTORY BP Station No. 11192 was built in 1976, and operated by Mobil Oil Company j'•. until it was purchased by BP Oil in 1959. A soil vapor survey 1ras conducted as part of that sale whic.•h found hydrocarbons in soil gas samples. in April _ 1990, four groundwater monitoring wells were installed. This effort determined that both-soil and groundwater contained hydrocarbon constituents. In January 1991, the station was closed for renovation. USTs were removed in early February and additional hydrocarbons were found at that - ! time. Figure 2 shows the location of fuel storage and delivery systems prior to their removal. 1.2 SITE GEOLOGY/HYDROG�OLOGY The site i - { , s located in a fiat, near sea-level area underlain by alluvial sediments to depths of thousands of feet. Groundwater occurs at a depth of 0 to 100 feet in the area and flows northeastward. Site hydrogeology has been investigated to a depth cf 30 feet. . Sediments consisted of a black clay (weathering profile) to about_ .-. underlain -- feet, underlain by brown lean clay (dominantly) to the limit of ex�laration. A clayey sand was present in several well bores at 22 to 26 feet. Groundwater was,present.a.t 23 to.25 deet when wells were installed in April 1990. By December 1990 the wells had _.iA:f NG:9205/03.291 ;