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fff Santa Fe Pacific Pipeline Partners, L.P. J-6075.03 <br /> L� January 6, 1994 STOCKTON WORK PLAN Page 2 <br /> detected in the subsurface. Floating hydrocarbon product up to six inches <br /> thick was detected in several test pits during LF's investigation. However, <br /> based on product analysis and pipeline testing, LF concluded that the <br /> hydrocarbons in the subsurface did not originate from a SPPL pipeline leak. <br /> Results of the Levine-Fricke investigation are presented in a report titled: <br /> "Investigation of Subsurface Fuel Hydrocarbons, Southern Pacific Pipelines", <br /> dated March 23, 1988. <br /> In March 1989, Hydro-Search, Inc. conducted a subsurface soil and <br /> groundwater quality investigation at the SPPL Stockton Terminal to evaluate: <br /> regional and site specific hydrologic conditions; the impact and extent of <br /> hydrocarbons in the subsurface; and the potential movement of the identified <br /> hydrocarbons. The Hydro-Search investigation identified aromatic <br /> hydrocarbons, diesel and gasoline in the soils and groundwater beneath the <br /> site. Groundwater monitoring wells M-1 through M-4 were installed at that <br /> time. Results of the Hydro-Search investigation are presented in a report <br /> titled: "Groundwater Investigation and Environmental Assessment, <br /> Stockton Terminal, Stockton, California", dated April 28, 1989. <br /> In July 1992, Hart Crowser conducted a preliminary subsurface investigation <br /> to further characterize the horizontal and vertical extent of the dissolved <br /> hydrocarbons beneath the site and to determine the presence of a potential <br /> onsite source of hydrocarbons. The results of the investigation indicated that: <br /> ■ It is possible that an offsite, upgradient source of petroleum <br /> hydrocarbons is impacting the groundwater beneath the site. <br /> ■ The soils in the vicinity and downgradient of the manifold/prover loop <br /> area had been impacted by hydrocarbons and some downgradient <br /> migration of the hydrocarbons had occurred. The details of the <br /> preliminary subsurface assessment are presented in a report titled, <br /> "Preliminary Site Assessment, Santa Fe Pacific Pipeline Partners, <br /> Stockton Terminal, Stockton, California", dated September 3, 1992. <br /> In November 1992, RWQCB requested that SFPP install a monitoring well <br /> into the lower groundwater bearing zone (B-zone) to assess the vertical <br /> groundwater gradient and to determine the quality of groundwater. On <br /> February 11, 1993, Hart Crowser submitted an addendum to the Additional <br /> Site Assessment work plan for the well installation to the RWQCB. The well <br /> was installed during the last week of April 1993. <br />