2011-09-30_REVISION - M1981185 - Laserfiche WebLink

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Sixth Adequacy Letter, Amended CN -01 May Day Idaho Mine Complex, M- 1981 -185 a. The Division had determined some of the proposed mining activities pose minimal potential to affect surface or ground water quality. Such activities may commence after the issuance of CN -01 and prior to the Division's approval of adequate hydrologic information for surface and ground water. These activities are limited to the following: • Stabilization and reconstruction of illegal access road from County Road 124 to bridge; • Grading of pre- existing access roads; • Installation of storm water management structures; • Excavation of the collapsed portal at May Day 1 level and establishment of a stable highwall and mine bench at the May Day 1 level; • Removal of soil, rock and mining related debris from the drainage channel of Little Deadwood Gulch at the Chief Portal and May Day 2 level; and • Corrective measures as necessary to comply with enforcement actions issued by other agencies, with written approval from the Division. b. The Division had determined some of the proposed mining activities pose significant potential to affect surface or ground water quality. Such activities may not commence until the Division receives and approves hydrologic information adequate to fully characterize baseline conditions for surface and ground water, and a hydrologic monitoring plan sufficient to verify compliance with water quality regulations. These activities, which cannot commence until hydrologic baseline conditions have been approved by the Division through a permit modification, include the following: • Mill retrofit and commissioning; • Ore stockpile consolidation; • Construction of the augmentation pond; • Mill optimization; • Production at May Day 1 level; • Production expansion; and • Milling completion and closure. The Applicant has committed to modifying Exhibit D, Mining Plan, to comply with this adequacy issue. The mining and milling activities listed above in paragraph 11.b. may not occur until the Division has reviewed and approved, through the Technical Revision and /or Amendment process, the following: 1) sufficient surface and ground water data to appropriately characterize baseline conditions; 2) a monitoring plan sufficient to verify compliance with water quality regulations; and 3) Environmental Protection Facility certifications for the entire mill facility and tailings disposal location(s). 12. In a correspondence dated September 16, 2011, WQCD confirmed an individual NPDES discharge permit must be obtained for the discharge from the Idaho No. 1 Adit. WQCD indicated the discharge could not comply with receiving stream standards without treatment or dilution of the receiving stream. 8