SITE INFORMATION AND CORRESPONDENCE

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City of Stockon • • Department of Housing and Redevelopment 2 24 September 2004 not discuss how the RDA will collect samples from the provided. excavation. This information must be 5• The Revised Work Plan does not include analysis for total petroleum hydrocarbons (TPH) as gasoline, but lists it as a constituent of concern in the Health and Safety Plan. The RDA must include TPH as gasoline analysis for soil and groundwater samples. 6• The Revised Work Plan proposes soil borings to 20 feet below ground surface. The soil borings should terminate a few feet into the groundwater so that appropriate grab groundwater samples are collected. Therefore, soil borings may terminate deeper than proposed in the Revised Work Plan. 7. The first bullet on Page 5 of the Revised Work Plan lists the proposed analytical methods for "selected samples." The RDA needs to provide a discussion of how the field geolost will determine which samples to submit for testing. gi 8. The second bullet on Page 5 of the Revised Work Plan states excavation and resampling will continue until cleanup goals are met. Cleanup goals for this site are non-detectable or background concentrations. 9• The last bullet of Page 5 is not complete. If there are detections of TPH, volatile organic compounds (VOCs), semi-volatile organic compounds, or polynuclear aromatic hydrocarbons in soil, that soil may not be used for fill in the excavation. For the metals detected in soil, the RDA needs to run a waste extraction test using deionized water to determine how if the meta] concentrations in soil are acceptable for use as fill in the excavation. 10. It is unclear why the Revised Work Plan lists WET test for groundwater samples on page 7 and not for the soil samples proposed in the fifth bullet on Page 6. The RDA needs to clarify the sampling proposed on Page 7 and in fifth bullet of Page 6 and include that the RDA will not filter any of the groundwater samples. 11. The Health and Safety Plan included in Appendix D of the Revised Work Plan states VOC monitoring will occur"periodically." The RDA needs to define"periodically" and provide a more detail explanation of the VOC monitoring on-site. 12. Page 3 of the Soil and Dust Management Plan, which was included in Appendix D of the Revised Work Plan states,"air monitoring will be performed during all site activities in which soil containing elevated lead concentrations or potentially elevated concentrations of lead are being disturbed or handled." The RDA will continue air monitoring and dust control measures for the duration of the project. Regional Board staff concurs with the Revised Work Plan provided that responses to the above comments are received a minimum of two weeks prior to the field week, but no later than 22 October 2004. By 28 January 2005, please submit an investigation report detailing the field