1996-02-06_REVISION - M1977493 (16)

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e Mr. Allen Sorenson Division of Minerals and Geology February 1, 1996 Page 5 Technical Exhibit No. 4 contains a geochemical analysis of waters located at the toe of Dam 5 at the Mayflower Tailing Impoundment compared to water located at GWM #1 and GWM #2. The data indicate that water chemistry profiles in the monitoring wells do not match the chemistry of waters at the seep. Water at the currently established wells is demonstrative of whole basin water chemistry including, but not limited to, water treated at the Mayflower Treatment Pond, intercepted and diverted water east and west of the Climax process facilities, and water from nearby Humbug, Tucker, and Mayflower drainages. CMC feels that the Division's argument that GWM #1 should be used as a point of compliance because of its proximity to the Climax facilities is unrealistic. 3) Any ground water discharge to Tenmile Creek above GWM #2 is regulated by the Climax CPDS permit, the outfall for which is located between GWM #1 and GWM #2. Your point number 3 cites the argument that "where ambient ground water quality exceeds values for the protection of existing and reasonably potential future uses of ground water, permit conditions shall be established to protect those uses..." Ambient ground water quality does not exceed the existing or reasonably potential use of ground water for protection of the ground water use in the Tenmile Creek Valley. Stream standards are met by compliance with the CPDS Permit. Given the above points, GWM #2 is the appropriate compliance point for the Tenmile Creek Valley. CMC is willing to share analytical data from GWM #1 with the Division. The same discussion for numeric protection levels presented for GWM #2 also applies to GWM #1. Arkansas River Valley Please note the discussion above concerning the establishment of an additional well in the Arkansas River basin west of the Mosquito Fault. Eagle River Valley CMC concurs with the Division that, under Rule 3.1.7(6)(a), 'protection afforded ground water' requires the establishment of one or more points of compliance. CMC will work with the Division to either use the existing EVMW, located down-gradient of the cut-off wall for seep waters from Robinson Lake, or to develop a new well as a new point of compliance for future monitoring in demonstration of the cut-off effectiveness. CMC will work with the Division to establish numeric protection levels based on an evaluation of surface and ground water flows associated with an Eagle Valley well. It is not possible to determine a multiplier for this well at this time due to unknown flow conditions following construction of the cut-off. In the interim, no numeric protection levels would be applicable. CMC will, however, share interim analytical data with the Division.