SITE INFORMATION AND CORRESPONDENCE

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_ J Lodi Groundwater; Busy Bee C ,hers - 2 - April 30, 2002 Phase 1 RDFS Work Plan beneath the alley adjacent to the site need further investigation as to their location and condition (video logging). These investigations should be included in the phase 1 work so that the information is available for the purposes of planning the phase 2 work. 4. Soil gas samples should be collected from the boreholes at selected intervals in lieu of, or in. addition to, soil samples. Soil gas sampling has proven to be a reliable technology and is a better indicator of the more mobile, gaseous contaminant fraction. The RWQCB no longer believes that soil samples alone are sufficient to characterize a VOC site due to deficiencies in soil sampling methods for VOCs and due to the way VOCs behave in the subsurface (VOC soil contamination may be hard to locate due to preferential flow paths, etc.). Soil gas results are necessary for estimating risk to both human health and groundwater quality and for determining the feasibility of remedial technologies such as a soil vapor extraction system. It is our experience that that soil sampling alone generally underestimates the mass of contaminants, and thus the threat, of VOCs at a spill site. 5. Because of the potential for hollow-stem augering to pull contaminants to to deeper zones and to reduce the production of contaminated drill cuttings, a push-technology drill rig should be used. 6. Boring and well locations should be surveyed. Also, data should be submitted in an electronic delivery format(EDF). 7. Neat cement grout should be used when decommissioning all soil borings and for backfilling a groundwater monitoring well boring annular space above the bentonite seal. 8. The bottom sample tube should be used for chemical analysis and the middle tube should be used for lithologic description and field screening. Also, if soil samples are collected, preservation of soil samples for VOCs should be conducted in the field or at the lab within 48 hours of collection as required by US EPA Method 5035 (which replaced Method 5030). 9. Target depths for collection of soil and soil vapor samples should be stated in the work plan although some flexibility in the selected sample interval should be accorded to field personnel based upon field observations. We look forward to receiving the revised Phase 1 RI/FS Work Plan. Nothing in this letter is intended to relieve Busy Bee of any obligation imposed by law, a court or any other public agency. Performance of the subject work plan does not constitute completion by Busy Bee of its legal obligations to perform environmental investigation or remediation at or around its site. Although the Central Valley Regional Water Quality Control Board ("Board") and the Department of Toxic Substances Control (DTSC) have coordinated in preparing comments on the work plan, the comments below are on behalf of the Board only. You are advised to contact DTSC to obtain any required comments, oversight or approval. Please provide copies of any responses to comments and future submittals to the Board and DTSC.