SITE INFORMATION AND CORRESPONDENCE

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Ms. Frances Schmiedt, et. al. - 2 - 29 January 2003 useful information on activities that have occurred on the site. These interviews can provide valuable information that will be useful during scoping of the Phase II soil and groundwater investigation. In Task 4.0, the Report of Findings should also include the scope of the Phase 11 investigation along with the rationale for the proposed sampling. The following comments are specific to the second phase of proposed work: The Work Plan proposes to collect samples every five feet for lithology. A minimum of one boring must be continuously cored to record lithology. The Work Plan proposes monitoring well development. Monitoring well development must include recording physical parameters (temperature, electrical conductivity, pH, etc.). In Task 2.0, the Work Plan appears to reference a single soil boring and single temporary well. However, the proposed quantity, location, and analyses of samples should be based on information obtained during Phase I of the investigation. For risk assessment purposes, soil samples should be collected at the surface, 5 feet below ground surface (bgs), and 10 feet bgs. Additional samples should be collected between the 10-foot sample and the sample collected immediately above groundwater if contamination is identified in this interval. In Task 2.0, the Work Plan states, "A bentonite annular seal nor a surface seal will be installed on the temporary well." The "nor" in this sentence should probably be "or". You need to clarify the type of seal to be installed on temporary wells. Additionally, the temporary wells need to be developed to remove any fine sediments and allow collection of representative groundwater samples. The detection limits for soil and groundwater analyses must be adequate for risk assessment purposes. In addition, the Phase II Work Plan must include a description of the quality assurance/quality control process that will be employed for reviewing analytical data obtained for the site. Task 5.0 needs to include providing the direction of groundwater flow based on the temporary wells. This task also should include providing a discussion of how soil and groundwater results will be evaluated to determine if there is a threat to human health or the environment given the absence of background samples. The Phase II Work Plan should consider collecting background samples for comparison of results to characterization samples. We concur with the first phase of the investigation proposed in the Work Plan provided that the Comments 1 through 3 are incorporated. By 4 April 2003, please submit the findings from the first phase of work with a work plan for the soil and groundwater investigation. The work plan should include a schedule to perform the work and incorporate the above comments. A copy of