SITE INFORMATION AND CORRESPONDENCE

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Wendy L. Cohen -2- 14 February 1994 In November 1992, leftover soil samples were retested for soluble lead using deionized water in the WET lab procedure instead of a citrate buffer. Soluble lead was non-detectable in all of these analyses. In December 1992, 14 surface soil samples were taken at the site and analyzed for lead. Results showed at least 32,000 square feet of surface soil with lead concentrations greater than 500 mg/kg. The full lateral and vertical extent of the contamination was not yet defined. In June 1993, 45 surface soil samples were taken at the site. Nine of the locations were sampled vertically: at the surface, one foot bgs and two feet bgs. Results revealed that the full lateral and vertical extent of lead contamination in the soil still was not defined and that offsite sampling would be needed. COMMENTS RECENT WORK PLAN A 17 December 1993 work plan for further site characterization was submitted by Industrial Compliance (IC). The work plan includes the following: 1. Analysis of 20 surface soil samples for soluble lead and 16 soil samples from a depth of three feet for total lead. Four samples also will be analyzed for chromium. 2. A proposed soil cleanup level for lead of 241 mg/kg. 3. Installation of one ground water monitoring well, and analysis of samples from that well and from the two existing wells at the site for 17 metals and the general suite of minerals. 4. Utilization of soil information collected previously and from the above proposals, to evaluate the potential for degradation of ground water quality from site soils. The proposed cleanup level of 241 mg/kg is a conservative estimate derived from a health risk based, soil lead action level model developed by the California Department of Toxic Substances Control (DTSC, 1992). They propose to carry out the soluble lead analyses using deionized water in the WET procedure. They note that they have received verbal permission from the Board to do this as long as the detection limit is a maximum of 50 gg/1 (based on the drinking water standard) and the pH of the soil is at least 6.0. Comments 1. The detection limit of 50 µg/1 for soluble lead is no longer acceptable because the drinking water standard was revised to 15 p g/1 in July 1993. Also, Cleanup and Abatement Order No. 92-707 issued to SPTCo for the Tracy Yard across the street from this site lists a ground water cleanup level for lead of 15 14g/l. Therefore, the maximum detection limit for lead should be 15 g g/l.