2004-04-12_REVISION - M1977424 - Laserfiche WebLink

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_ ~ = Western Water & Land, Inc. ~~ Apri19, 2004 Mr. Steve Shuey / Colorado Division of Minerals and Geology !/ Departrnent of Natural Resources Grand Junction Field Office 101 South Third Street, Room 301 Grand Junction, CO 81501 RE: Response tyl.ogan Wash Mine hnical Revision Evaluation (Permit M-77-424) Dear Mr. Shuey: No. 4 Research Mine Portal Seal Western Water & land, hoc. (W W[,), agent for Glenn Springs Holdings, Inc. (GSHI) and Occidental Oil Shale, Inc. (OOSI), has prepared this letter in response to the Division of Minerals and Geology (DMG) letter of March 26, 2004 which contains an evaluation of the Research Mine portal seal as described in Technical Revision fI'R) No. 4 for the Logan Wash Mine. The DMG evaluation asks that the operator more specifically define the proposed period of monitoring during the "spring runoff season" and imposes several monitoring stipulations for head build-up within the sealed mine. The monitoring stipulations include: 1. Monitor the head within the sealed mine on a weekly schedule during a specific monitoring period of the yeaz. 2. Should the head pressure exceed 1.5 pounds per square inch (psig) or a level of 3.5 feet behind the concrete dam, or if any signs of instability such as seepage occur, immediate reporting (within 24 hours) to DMG is required. 3. Should the head pressure exceed I.5 pounds per square inch (psig) or a level of 3.5 feet behind the concrete dam, the opemtor will draw down the level of water in the mine by opening the valve in the discharge pipe outside of the sealed portal. in addition, DMG requires that the opemtor demonstrate that there is no near term short-circuiting from the mine pool to the surface in the form of seeps or springs. Mine Head Monitoring Period While preparing TR No. 4, W WL, studied the discharge daffi available for the Research Mine. These data show that the for the period between 1993 and 2003, the period of discharge began as eazly as April ], (1999) and ceased as late as December 30 (] 998). No flow occurred in 2002, in 2003, flow was held back by the concrete dam and water levels did not exceed cone-foot depth. As the data suggest, it would be logical to establish the monitoring period as April through December. However, W WL proposes that once head build-up (in Feet or in pressure) has subsided to zero after reaching a peak level, that no further weekly monitoring should be required for that season. If, for example, after a moderate head build-up in the spring, the head falls to zero by the end of June, weekly monitoring AppGcarionsin Earth Science 743 Horizon Court Suite 330, Grand Junction, CO 81506 Phone: (970) ?A2-0170 Fax: (970) TA2-0270