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Wendy L. Cohen -2- e. Results show that the tracers were not detected along the Mobile/Shell pipeline or the SFPP Mainline. However, 32 of the 54 samples at the Time Oil line had detectable levels with detection limits ranging from <1000 to <10000 with unspecified units. Most of the positive results were on the sourthern end of the Time Oil property. Five other locations also had detectable levels: four at the northeast corner and one near the western end of the tank farm. Tracer Research Corporation (TRC) says "It is highly possible that the tracer was released above ground and that the soil gas detection has resulted from vapor contaminaion (sic) from above ground." If the tracer was released as a gas, dispersion into the ground would occur only if the gas was heavier than air. Otherwise, it would volatilize into the atmosphere. If the tracer was released as a liquid, it would seep into the ground. Once in the ground, its fate would depend on the amount released and its characteristics, but the concentrations would decrease radially from the point of release. The report does not discuss the phase of the tracer that might have been spilled or the point of release. Nevertheless, regardless of the phase of the tracer, the above supposition would not explain the positive findings at the northeast section of the tank farm. The tracer could not have been released at this location since the highest concentration was detected at SG-45 approximately 300 feet southwest. The other scenario of underground release through leaks in the pipeline seems more plausible. This would explain the positive results detected along the pipeline and also at the northeast section of the tank farm since there are pipelines leading to the tanks. f. The report concludes that the Mobile/Shell Pipeline and the SFPP Mainline were not leaking. It also states that uncovering of the section of Time oil line which had detectable levels of tracer gas indicated that the line was not leaking. However, the report does not specify whether the bottom section of the pipeline was exposed. Exposure of the bottom section of the pipeline would have ascertained the presence or absence of leaks. g. The report does not provide QA/QC documents. In conclusion, the leak detection test results are unreliable. 2. Investigation of Subsurface Fuel Hydrocarbons, Southern Pacific Pipelines, Inc. I concur with a previous conclusion by Board staff that the fingerprint charac- terizations (gas chromatograms) in this report showed the floating product along the SFPP pipeline matched the chromatograms of regular and unleaded gasoline samples collected directly from the SFPP pipelines at the Stockton terminal which were used as standards for the analyses. Thus, SFPP could be the contaminant source. 3. Ground Water Investigation and Environmental Assessment, Stockton Terminal , Stockton, California. This investigation found soil and ground water contamina- tion at the site. However, the horizontal and vertical extent of contamination was not defined and a proposal for additional work was not included. The report also indicated the ground water flowed to the northeast based on ground water elevation measurements from 17 November 1988 to 9 December 1988. Based on this flow direction, all onsite monitoring wells are downgradient of SFPP's loading racks, tanks, and associated piping. Ground water elevation measurements by Emcon Associates in June 1989 show the ground water trending east-southeast. This flow direction still places all the monitoring wells except M-2 downgradient