1994-06-06_REVISION - M1977378 - Laserfiche WebLink

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r A Ms. Patricia Nelson June 1, 1994 Page 2 Division of Minerals and Geology ("DMG") (All correspondence originating from SGC has been copied to you for your information and file), four internal bulkheads have been constructed to-date. A Technical Revision (TR-016) was submitted to and approved by the DMG that, among other items, will allow the Terry Tunnel bulkhead to be constructed with a drainage pipe and valve thereby giving SGC some flexibility in construction and control over drainage after construction. The American Tunnel bulkhead, of course, will also be constructed with a valve. The construction schedule calls for the Terry Tunnel bulkhead to be constructed next, followed by the American Tunnel bulkhead. It appears that realistically the Terry Tunnel bulkhead could be completed by the end of July, 1994 and the American Tunnel bulkhead could be completed as early as September, 1994. This schedule would allow up to 4 data points for most of the seep monitoring sties. No final decision has been made on the schedule for building the American Tunnel bulkhead. Has the monitoring program been revised per our concerns? The monitoring program has not been changed from that approved by the DMG and summarized in the November 10, 1993 letter attachment. SGC and the Division have a basic difference of opinion on the use of the monitoring program and SGC's responsibilities. This basic difference needs to be resolved either through negotiation or judicial action. To this end, as you are aware, SGC has filed a request for Declaratory Judgment. Concurrently, SGC would welcome a dialogue if the Division believes there is room for agreement based on previous meetings and correspondence. Please advise me. Has the bromide been introduced into the mine? Bromide has not been brought on-site and will not be until after the Terry Tunnel bulkhead is completed. The Division has questioned the toxicity of bromide and the potential for stratification. Attached is a poster presentation that addresses the subject of toxicity. At SGC's target concentration (1 ppm) there should be no acute toxicity or sublethal chronic effects. This concentration is the same as that recommended in the attached poster presentation for protection of water quality, therefore it is believed that using the tracer will not have adverse toxic effects on the waters of the State, even in the unlikely event that bromide were eventually to find its way to the surface. The DMG was concerned with density settling, which would be the most likely mode of tracer failure (although density settling would not be likely at the proposed concentrations). Annual samples will be taken at the American Tunnel bulkhead (the lowest point in the system) to address this concern. In addition, we would be interested in any additional monitoring data which was gathered subsequent to your previous submittal to the Division.