SITE INFORMATION AND CORRESPONDENCE

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Mr. Joseph Salazar, Jr Former Busy Bee Cleaners -2 - August 20, 2003 RDFS Work Plan In sum,Busy Bee proposes to install 3 dual completion SVE wells, 2 dual completion sve/ozone sparging wells, 4 ozone sparging wells, 4 additional groundwater monitoring wells, 1900 feet of buried pipeline, vapor and liquid phase carbon treatment systems, and ozone generation equipment. Comments on the Work Plan The document proposes a substantial amount of work that should serve to greatly increase the definition of the conditions at the site such that Busy Bee will be much closer to being able to select and implement an appropriate remedy for the site. Based on the results of the proposed work,particularly the analytical results of samples taken from the proposed new monitoring wells, the possibility remains that additional characterization efforts may be needed. However,the work proposed represents the logical next steps towards remediation of the site. There are some identified deficiencies associated with the work plan itself that will need to be corrected prior to our concurrence with the work plan. In general, those deficiencies are as follows: 1. The Health and Safety Plan(HSP)presented in the report was prepared in support of the Phase 1 and Phase 2 Site Investigations. The proposed work involves many construction-related activities that were not contemplated in those investigations. The HSP needs to be updated to address health and safety concerns regarding the trenching, treatment plant construction and operation, and ozone generation activities. 2. Section 2.6 ("Preliminary Remedial Goals, Soil Screening Levels,Risk-Based Screening Levels and MCL") contains information related to some of the published values for threshold PCE contamination levels of concern for various media and exposure pathways. We recommend deletion of section 2.6 and instead, Busy Bee should include a section in the Feasibility Study that develops site-specific vadose zone remediation goals based on 1)human health risk and 2) threat to groundwater quality. Vadose zone remediation levels will be the lower of these two remediation goals. An analysis of threat to groundwater quality(a"water quality site assessment"or WQSA) is performed by modeling the impact to groundwater caused by the residual levels of contaminants in the vadose zone. Soil moisture that which enters the groundwater(recharge water or leachate) must meet groundwater cleanup levels. Groundwater cleanup levels will be based upon the Regional Board's Central Valley Basin Plan that requires, as a point-of-departure, cleanup to background levels (i.e., non-detect for PCE). Cleanup levels may be above background based upon a technical and economic feasibility analysis but in no case can cleanup levels exceed maximum beneficial use levels. Health-based cleanup levels for PCE are established by calculating the residual levels that do not pose an unacceptable residual human health risk, including an analysis of the potential health risks associated with indoor air. Indoor air risks are estimated using the Johnson and Ettinger Q &E)model. Busy Bee needs to become familiar with the J&E model and include in its RI work plan the activities necessary to obtain the data required to input to the model.