2002-04-16_REVISION - M1977342 - Laserfiche WebLink

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STATE OF COLORADO DIVISION OF, MINERALS AND GEOLO Department of Natural Resources ~ /p y'[ /~ ~ 1313 Sherman St., Room 215 Permit #: ~ ~1 /77'7'1 ~ Confidental?: / ~ Denver, Colorado 80203 O18SS: -7-~__ Type-SE:q.: DIVISION O F Phone: (303) 866-3567 From: To: it1,,,ce MINERAL S FAX: (303) 832-8106 Doc. Name:5 ~ e .s csa I• w a (• 2 April 16, 2002 Doc. Date (if no da a stamp): lt -~(,La7- G E O L O G Y RECLAMATION MI NING•SAFET7 Mr. Tony Lucero ~ -- -- --- ' Bill Owens Climax Molybdenum Company Governor P.O. BOX 68 - Greg E. Walther Emptre, CO 80438 Executive Director Michael B. Long Division Director RE: Water Treatment Sludge Disposal in Pond I.2, Henderson Mine, Permit No. M-1977-342, Technical Revision No. TR-008 Deaz Mr. Lucero: Thank you for your letter dated April 9, 2002 proposing specific procedures for disposal of dewatered high-density sludge generated at the Urad wastewater treatment plant into Pond 1.2 at the Henderson Mine. The Division of Minerals and Geology (DMG) approved the disposal of Urad sludge into Pond 1.2 through the conditional approval of technical revision TR-008 on September 7, 1999. The condition to approval of TR-008 was that: The Henderson-Mine will develop a strategy to protect the geosynthetic liner in Pond 1.2 during placement of sludge. No sludge will be placed in the pond until liner protection measures have been reviewed and accepted by the Division of Minerals and Geology. Subsequent to the conditional approval of TR-008, DMG approved Henderson's proposal for sludge disposal from a conveyor belt, but required certain descriptions and commitments by Henderson to assure that no rocks with the potential to damage the geosynthetic liner would be dropped from the conveyor belt into Pond 1.2. The DMG is satisfied that adherence to procedures described in your letter dated Apri19, 2002 to prevent the introduction of potentially damaging rocks into Pond 1.2 will provide adequate protection for the liner. The DMG is further satisfied that disposal of sludge into the pond using a front end loader where travel over the lined surface by the loader is prevented, as described in your April 9, 20021etter, will not result in damage to the liner. In consideration of the foregoing discussion, the DMG hereby approves Henderson's plan to dispose of Urad sludge into Pond 1.2 using either a conveyor belt system or a front-end loader where contact of the loading equipment with the geosynthetic liner is prevented. DMG further approves Henderson's plan to wash sludge into the bottom of the pond using water hoses. However, it is the DMG's direct experience that a focussed stream of water under high pressure can damage geosynthetic liners; Henderson is advised to carefully observe liner washing operations and control water pressure to assure that the liner is not damaged within the body of the geosynthetic panels or at the seams. The Henderson Mine letter dated Apri19, 2002 describes the use of earthmoving and compaction equipment on the liner as well as placement of gravel and compacted fill on the liner. The DMG has identified the following issues to be finalized prior to approval of the placement of liner cover fill.