REVISION - 12/1/2009, 7:12:39 AM-JWD

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radium -226 concentrations. As raised in previous comments on that previously proposed modification, Powertech had used this one measurement to conclude that the entire aquifer has elevated uranium and radium. As then, this single analysis is insufficient, and inappropriately assumes complete homogeneity of the aquifer. Regarding this lack of pre- activity data, the undersigned recently submitted comments to EPA regarding this proposal, similarly identifying the lack of comprehensive data necessary to evaluate and protect against the impacts of the proposed activities, among other concerns relevant to DRMS review. These comments are attached as Exhibit 1 hereto, and are fully incorporated herein by reference. Of particular note with respect to the lack of baseline data is the discussion in the letter at pages 2 -3. Apart from the lack of baseline data, there is no information as to the length of the screened interval in the well. Rather, Powertech simply states that "[b]ased on the geophysical logs the completion interval and screen length will be determined on a. site - specific basis." Powertech Request for Modification, Appendix 1 at p. 5. In order to provide sufficient information, the wells must be screened through the entire thickness of the aquifer, rather than just the ore zone within the aquifer. The wells must be developed until the turbidity falls below acceptable standards, as suspended particles in a water sample can result in high uranium and radium values. While the Request indicates that some of the wells to be used are already in existence, there is also no information as to how long the wells were developed and whether any turbidity measurements were taken prior to taking any previous samples. Additional critical technical information is also lacking. For instance, there is no demonstration as to how pumping the relatively large amounts of ground water involved is likely to change the hydraulic flow within the aquifer, which can lead to changes in groundwater quality (e. g., flow from reduction zones into more oxidizing zones could lead to iron oxyhydroxide precipitation and well fouling). The proposed volume should be compared to local use of the groundwater aquifer in order to determine the level of stress the proposed activities may put on the aquifer flow geometry. This is critically important due to Colorado Geological Survey publications indicating that "recent mineral exploration drilling activities and water extraction from existing wells appear locally to have altered natural flow paths..." (Hydrogeologic and Stratigraphic Data Pertinent to Uranium Mining, Cheyenne Basin, Colorado - Kirkham, O'Leary, and Warner. Colorado Geological Survey, 1980, at 18). The Request also lacks any information related to the multitude of historically drilled wells, exploration and bore holes, or other holes in the immediate vicinity that may affect the hydrologic balance or groundwater quality during any aquifer pump tests (this issue is addressed extensively in Exhibit 1 at 4 -6). The Request also fails to provide any information or description on how reinjection of the groundwater may impact the aquifer. Powertech states that no additional pressure will be needed to inject the water, relying instead on gravity flow, but does not indicate how long this might take. Powertech proposes to collect water samples from the pump wells. If the company is permitted to perform the pump test, the water quality samples should be collected at the end of the pump test before it shuts down the pumps. This will provide some assurance that the groundwater zone affected by drilling fluids has been flushed out prior to collecting the sample. Additionally, the sample should be collected from a well that is screened through the entire thickness of the aquifer. These issues all further demonstrate the need for this activity to be coordinated with, and approved only after completion of, a comprehensive baseline characterization plan.