SITE INFORMATION AND CORRESPONDENCE

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Mr. Roy Thun • -2- • 18 November 1993 The work plan does not specify which areas are not fully defined and how these areas would be affected if interim remediation is implemented. The work plan also does not say what remedial actions in Zone A could adversely affect Zone B. Since Zone A is a source to Zone B, any remedial efforts in Zone A should reduce the potential to impact or further degrade Zone B. Furthermore, a phased approach to investigation and cleanup should be employed as stipulated in State Water Resources Control Board Resolution No. 92-49. Adjustments can be made along the way until the entire site is remediated. Obviously, remediation should not be conducted where there is a potential for spreading the contamination. 2. The report states shat the extent of contamination at non-STTC member tcaiuinals has not been fully defined, and the STTC should not be required to clean up contamination caused by other responsible parties. Once again, the work plan does not specify which non-STTC members have not identified the extent of contamination at their sites. However, since there are only three other potential sources in the general vicinity of the Port of Stockton fuel terminals which are non-STTC members, it is clear that the work plan refers to Santa Fe Pacific Pipelines (SFPP), Union Pacific Railroad, and Unocal. Union Pacific Railroad sold its storage tanks, piping, and other ancillary facilities to ST Services in 1988 after an investigation indicated no evidence of contamination by petroleum hydrocarbons. Therefore, there are actually only two non-STTC members, namely, SFPP and Unocal. SFPP has an on-going investigation and a monitoring program. A source investigation has recently been completed. The report was submitted on 15 November 1993 and is under review by Board staff. Unocal's contamination related to its underground tanks appears to be completely defined as far as petroleum hydrocarbons are concerned. (The facility used to store stoddard solvent in a 10,000 gallon underground storage tank. Stoddard solvent contains chlorinated hydrocarbons and may be the source of chlorinated hydrocarbon contamination which has been detected in the past). According to Mr. Harlin Knoll of the San Joaquin County Public Health Services, Unocal's monitoring results for May 1993 show nondetectable levels of petroleum hydrocarbon constituents except for monitoring well (MW) 5. We are not aware of any Unocal structure or equipment in the vicinity of MW 5, except maybe the vapor flare whose location was not shown in the 1 September 1988 and 29 June 1989 assessment reports and subsequent monitoring reports for Unocal. In fact, the 1 September 1988 and 29 June 1989 assessment reports also show that the northeastern area in the vicinity of MW 5 was subleased to ST Services. The status of this sublease is unknown. Interim remediation measures can be selectively applied so that they do not influence areas which have not been defined or have contamination that could be spread by the remediation measures. For example, vapor and/or ground water extraction wells can be placed away from SFPP's source areas to prevent spreading or cleaning up SFPP's contamination.