SITE INFORMATION AND CORRESPONDENCE

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Antonia K. J. Vorster 3 �) 28 November 1989 a location with negative TVH levels, and consider locating wells based upon the results of the soil vapor survey. 5) Prior to the purging of the wells, the ground water table should be inspected for the presence of a floating layer of product. The thickness of this layer, if present, should be measured. 6) Attached is an internal memorandum regarding the presence of hydrocarbons in the shallow ground water approximately one mile east of the Tracy Orchard site (See Figure 1) . The Tracy Orchard investigation should be expanded to evaluate if the Chevron pipeline leak is the source of the hydrocarbon contamination identified in this memorandum. The most likely pathway for contaminant migration, to this off-site area, are the granular backfilled trenches in which the utilities, including the Chevron pipeline, are buried. Information on the types of utilities buried within the Grant Line Road right-of-way, their total depths, backfill materials, and the . dimensions of the backfilled trenches, should be collected. The details of the pipeline leak (i .e. , duration, depth, product type) , soil cleanup activities, and the depth to shallow ground water should all be considered, in conjunction with the information on the utility trenches, to determine if these trenches are potential pathways for contaminant migration. If it cannot be conclusively determined that the utility trenches are not potential pathways, then a work plan to sample the trench backfill materials must be developed. 7) Finally, based upon the results of the soil vapor survey it appears that the ground water contamination is fairly limited. Since the dewatering well , DW-1, has the highest concentrations of fuel contaminants, I suggest that cleanup commence as soon as possible with the extraction of ground water from this well . The complete assessment of the extent of the ground water contamination can be done concurrently with this cleanup. V