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HARLAN & ASSOCIATES, INC. <br /> Mr. Walter Avramenko <br /> Colorado Department of Public Health & Environment <br /> June 3, 1996 <br /> Page 3 <br /> from the pile. The appropriateness of the location of GS-1 for assessing water quality <br /> is also supported by observations in the field of ground-water discharge from the toe of <br /> the Sutey Pile immediately upgradient of the well. <br /> Similarly, the Sutey Pile underdrain is suitably located within a naturally-occurring <br /> topographic depression formed by the drainage that formerly flowed through the area <br /> now underneath the Sutey Pile. In summary, both the Sutey Pile underdrain and existing <br /> monitoring well GS-1 are believed to be appropriately located to assess water quality <br /> exiting the Sutey Pile. <br /> 5. Comment: The plan proposes to collect ground-water samples from only two areas at <br /> the Coal Basin property: downgradient of the Sutey Pile and Maintenance Shop. <br /> Without knowing what activities occurred elsewhere on-site, it is currently not possible <br /> to say whether additional ground-water samples are needed downgradient of the other <br /> buildings, storage piles or ponds scattered across the site. A decision as to whether the <br /> sampling program should be expanded to other portions of the facility should be made <br /> following the historical review and field reconnaissance tasks. <br /> Response: In the initial phase of the site investigation, it is proposed to collect a <br /> combination of surface-water, ground-water and soil samples in order to assess whether <br /> or not there are potential environmental liabilities that can be identified with respect to <br /> the Coal Basin property. In this regard, one of the objectives is to assess if there are <br /> potential environmental problems related, for instance, to elevated metal concentrations, <br /> or improper disposal of industrial solvents, or other organics, and so forth. As such, <br /> during the initial investigations, it is proposed to sample seepage from each of the waste <br /> disposal facilities, namely the Old Refuse Pile, the Sutey Pile, and the Rock Tunnel <br /> Waste Pile. In addition, it is proposed to collect samples of the discharge from the <br /> haulage tunnels and seepage from the embankment which is directly downgradient from <br /> the former maintenance shop and yard. If environmental liabilities are identified, then <br /> additional investigations will be undertaken, as appropriate, to further evaluate the nature <br /> and extent of the problem. <br /> 6. Commen : All water samples will be analyzed for metals. Since naturally occurring <br /> ground water may contain measurable metal concentrations, the Division recommends <br /> that ground-water samples be collected from locations upgradient of the area being <br /> investigated. The facilities influence on ground-water quality may then be determined by <br /> comparing the background data to the downgradient sample data. <br /> Re=nse: The initial sampling and analysis program as detailed in the ESA Work Plan <br /> provides for collection of a limited number of samples (1) to assess whether or not there <br /> are potential environmental liabilities associated with the Coal Basin property, and (2) <br />