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J U N- 2 9- 9 4w W E D 1 3: 0 0 P. 0 3 <br />• • <br />Carl Mount <br />June 29, 1994 <br />Page 3 <br />Teohn~.oal Sasues <br />The aquifer descriptions provided in this report were apparently <br />lifted directly from Rocky Flats Plant-generated reports. The <br />alluvial aquifers are similar but the description should be written <br />more specifically for the proposed area. Both the Rocky Flats <br />Alluvium and the Valley Fill Aquifer within the Rocky Flats buffer <br />zone have received site specific use classifications in <br />"Clase:ifications and water Quality Standards for Ground Water" <br />3.12.0 (5CCR 1002-8). <br />The g~aologic situation of the bedrock aquifers differs from the <br />plant site and should be revised to reflect those differences. <br />The Arapahoe Formation is thin under the plant and is not likely <br />present under the proposed area. Discussion of the Arapahoe <br />Formation in the vicinity of the proposed area is contained in the <br />Phase II Geologic Characterization, "Surface Geologic Mapping of <br />the Rocky Flats Plant and vicinity Jefferson and Boulder Counties, <br />Colorado", March 1992. <br />The Laramie-Fox Hills Formation is upturned and outcrops or <br />subcrops to the west of the Phases 2-7 mining areas. Phases S-il <br />are directly, west of the upturned sediments. This upturned area of <br />the Laramie-Fox Hills is considered part of the recharge zone for <br />the Laramie-Fox Hills Aquifer and the unconfined portion of that <br />aquifer was also included in the Rocky Flats site specific ground <br />water classification. <br />Impacts to ground water quality and flow need to be discussed in <br />more detail in the application as they will affect the <br />hydrogeologic system in the Rocky Flats buffer zone. <br />9umma:ry <br />Based on the above concerns and comments, CDH requests that this <br />application process be delayed until the necessary federal agency <br />evaluations and decisions regarding the use oP the buffer zone are <br />completed. A letter from EPA to DOE on this matter is attached. If <br />you have any questions regarding our comments, please contact me at <br />692-3013. <br />Since~ely, <br />'~~. ~U <br />t ve Tarlton, Manager <br />Rocky Flats Program <br />