SITE INFORMATION AND CORRESPONDENCE

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PA/SI - 2 - 7 August 2000 California Army National Guard Facility- Stockton 1. Section 1.0,page 1, paragraph 1: This section states "The work plan was verbally approved by Mr. Robert Pierce of the CVRWQCB on August 13, 1999." Please change"Robert Pierce"to "Robert Reeves". 2. Section 2.1.1,page 3,paragraph 4: The groundwater results are summarized in Table 3. Change "Table 2"to "Table 3". 3. Section 3.2.1, page 7,bullet 6: This bullet states "Soil and soil vapor samples were collected at one location east of the former location of a 10,000-gallon gasoline UST ..". This sample location is actually west of the former UST. Correct this statement. 4. Section 3.6,page 9,paragraph 1: This section indicates laboratory analytical results from clarifier sampling were not available for inclusion in the PA/SI Report. It is unclear whether the PA/SI Report is referring to historical sample results or a sample that was collected while Versar observed the cleaning of the clarifiers on March 30, 2000. Revise this section to clearly indicate which results were not available and when these results will be provided to the CVRWQCB. 5. Section 6.1,page 16,paragraph 3: The PA/SI Report recommends decommissioning of the three groundwater monitoring wells at the AASF. This action is not supported by the monitoring data. A benzene concentration of 1.1 µg/1 was detected in well MW-3 during the last monitoring event in March 2000. This benzene concentration exceeds the Maximum Contaminant Level (MCL) of 1 µg/1 and the proposed Public Health Goal of 0.14 gg/l. Groundwater in the South Stockton area is used to supply drinking water, so these existing and proposed drinking water standards are applicable to the CA ARNG site. Remove this recommendation from the PA/SI Report. 6. Section 6.2,page 17: A hydraulic oil concentration of 1,630 mg/kg was detected in boring B-7 at a depth of 10 feet. This boring was collected near the washrack inside the CSMS building and no additional samples were collected from this boring to define the vertical extent of contamination. Add a recommendation to define the extent of this contamination. 7. Figure 4: The soil and soil gas sample location B15a is not shown on the figure. Add it. 8. Table 1: Discussions of metals results in the PA/SI Report involve comparison to background metals concentrations that are not tabulated anywhere. While we don't agree with comparison of site metals concentrations to background concentrations developed for the United States (see General Comment 1), any background values used for comparison should be tabulated in the PA/SI Report. Add these background metals concentrations or an alternative data set (per General Comment 1) to Table 1. The Preliminary Remediation Goal for lead in industrial soils is 1,000 mg/kg and not 11,000 mg/kg. Correct this value in Table 1.