SITE INFORMATION AND CORRESPONDENCE

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0 RI/FS Report Review -3- 5 July 1991 DDRW, Tracy Soils and ground water investigations in the southern portion of the site are very limited. Monitor wells have been installed in the southern portion of the site, however these wells have not been monitored and generally are not downgradient from the WMUs. The site-wide RI needs to be expanded to include a hydrogeologic analysis of the southern portion of the site, building the ground water level and quality data base by the installation and monitoring of additional monitor the wells, more monitoring of the existing monitor wells and implementation of soils investigations in each of the WMUs, if warranted. Waste Management Units Previous soils investigations (soils borings and soils gas) at Tracy have primarily focused on the detection of VOC contamination. Overall , there has been an inadequate soil/sludge sampling program for each of the WMUs because the WMUs have generally not been sampled for other potential contaminants such as heavy metals, pesticides and hydrocarbons. Additional soil sampling is needed in the WMUs to determine if there are contaminants in the soils or sludges and subsoils, whether the contaminants are at hazardous concentrations, at concentrations posing a threat to water quality and to determine the extent of the contamination. Based on Figure 2. 1-1 in the RI Report, the following WMUs are of primary concern and need to have additional soils investigations: the current industrial lagoons (3) , the old industrial lagoon (5) , the sump containing wastes from Recoup (6) , the burn pits (7 and 8), the medical supplies (10) , the embalming fluid dump (12) , the lube/oil dump (14) , the pesticide waste disposal trench (15) , the waste disposal area (16) , the fuel storage tanks (19) , the battery acid sump (21) and the hazardous materials storage area (22) . The other WMUs may have contaminants in the soils/sludges, but are not of primary concern due to the type of wastes disposed. The above listed WMUs should be sampled first and the list of analytes should be tailored to the type of wastes disposed in the WMUs. There is a limited amount of data which indicate that there is the potential for soil contamination by heavy metals and pesticides. The (Canonie) industrial lagoons sludge sampling data indicated that there are hazardous concentrations of copper, lead, mercury, Chlordane and DDD, DDE and DDT (organochlorine pesticides) . The heavy metals which appear to be at elevated concentrations are: arsenic, beryllium, cadmium, chromium, lead, mercury, nickel , silver, thallium and zinc. These metals should be considered for analysis, particularly in the WMUs which contained industrial wastes. Not all of the Title 22 metals may be need to be analyzed if Tracy can provide adequate rationale as to why these constituents may not be present. With respect to pesticides, there are six major types of pesticides: organochlorine and organohalide pesticides, chlorinated herbicides, triazine pesticides, organophosphorus pesticides, thiocarbamate pesticides and carbamate pesticides. Not all of the different types of pesticides may need analysis however, Tracy must provide adequate justification to eliminate any type of pesticides from analysis. The hazardous concentrations of pesticides and metals in the sludges in the industrial waste lagoons make these surface impoundments subject to the Toxic Pits Cleanup Act (TPCA) , Section 25208, et al . of the Health and Safety Code. The two major requirements of the TPCA are: 1) to cease the discharge of liquid hazardous wastes and hazardous wastes containing free liquids into the surface impoundment and 2) to submit a hydrogeologic assessment report (HAR) . The specific requirements of a HAR are listed in Section 25208.8 of the TPCA. Much of the work required for a HAR has already been