SITE INFORMATION AND CORRESPONDENCE

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t Warehouse Excavation Plan -2- 23 August 1991 DDRW, Tracy 6. Page 10. Section 3.7 states that treatment/disposal shall be off-site. If the analytical results of the top soil and subsoils reveal that there there are no hazardous concentrations of waste constituents and the residual waste constituents do not pose a threat to water quality, then the soil could remain on-site. 7. Page 18. Section 5.9 is entitled "Environmental and Personal Monitoring" . The discussions in this section are geared toward health monitoring and do not indicate whether the ground water will be monitored. Tracy should monitor the ground water in wells which are up and down gradient of the warehouse excavation. This may be accomplished by summarizing the existing data and sampling the wells for other potential contaminants (as listed in Table 1) , if needed. The down gradient wells which potentially need to be monitored are LM-13, LM-14, LM-21, LM-22 and the two Corps of Engineers wells in the area of Building 29. In addition, an up gradient well , possibly LM-11, should also be monitored for comparative purposes. If the existing data base is insufficient, then the wells should be sampled and analyzed for all of the same potential waste constituents that are being conducted for in the subsoil samples. Based on Table 1, the potential waste constituents include: Title 22 heavy metals (both filtered and non-filtered samples) , pesticides and polychlorinated biphenols (PCBs) , volatile organics, semi-volatile organics and cyanide. It is unnecessary for the ground water samples to be sampled for dioxins unless the subsoils samples have high concentrations of these constituents because dioxins are hydrophobic and tend to bind up in the soils. 8. Page 25. Table 1 lists the potential waste parameters and methods of analysis to be used for the samples from the drums, topsoil and subsoils and the burn pits. It is unnecessary to analyze for all of these potential parameters in all of the different type of samples for the following reasons. a. The top soil does not have to be sampled and analyzed for any potential waste parameters because the soils were above the original waste disposal sites. Potential soluble wastes from the disposal sites would move downward from the waste sites. b. Analyses for soluble concentrations of metals and pesticides need to be performed only on the subsoil samples. This information would be superfluous if performed on the drum samples. Analyses for total concentrations of metals and pesticides should be performed on the drum samples. c. Dioxins/Furans should not be sampled in the subsoils and would not need to be sampled in the burn pits if the analyses for pesticides and PCBs are at very low concentrations or are non-detect. It is known that in burn pits the dioxins are break down products from pesticides and PCBs. Therefore, analyses for dioxins should be withheld pending the analytical results of the pesticides and PCBs. d. Table 1 does not include analyses for total petroleum hydrocarbons (TPH) in the burn pits. It has been a common waste disposal practice to add fuel to a burn pit. Therefore, analyses for TPH, both gas and diesel , should be conducted on the burn pits samples.