_GENERAL DOCUMENTS - C1981017 (304)

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COLORADO DEPARTMENT OF PUBLIC HEALTH& ENVIRONMENT- Water Quality Control Division Rationale-Page 3 Permit No. COR-040000 IV. STORMWATER DISCHARGES ASSOCIATED WITH MINING OPERATIONS The stormwater regulations require that stormwater discharges associated with certain industrial activities be covered under the permit program. Mining operations are specifically included in the listed industrial activities. This general permit is intended to cover stormwater discharges from most active and inactive metal mines. It is also intended to cover stormwater discharges from mines (e.g., coal trines) which have individual CDPS permits for discharge of process waters. A. Types of Sites Covered This permit is intended to authorize most new and existing discharges composed entirely of stormwater from mining operations that are within Standard Industrial Classification (SIC) Code 10-Metal Mining and Milling, at sites that discharge stormwater only. This category includes active and inactive mining and milling operations, and remediation projects at such sites. This permit is intended to cover those portions of a metal mining or trilling site that are not already subject to effluent limitations under 40 CFR 440. Those previously uncontrolled areas which discharge stormwater that comes in contact with overburden, raw material, intermediate products, byproducts,finished products or waste products may be covered by this permit. Division policy number WQP-17 describes the difference between stormwater and process water at a mine site. This permit may also be used to cover existing discharges composed entirely of stormwater from any other metal or coal mining operations that are currently covered by an individual CDPS permits for discharge of process water. At the time of reissuance or amendment of the individual CDPS permit, terms and limitation from both permits may be combined into a new individual permit. Table I presents the categories of the mining industry and their CDPS Stonnwater pennit coverage. The Division intends to continue its practice to cover only one area with-each permit certification. As long as the operations or inactive mines are contiguous, one permit certification is sufficient. However, if a mine-waste remediation plan calls for removal of material and disposal at a location away from the mine-waste site, separate permit coverage must be obtained for the disposal site. B. Mine-Waste Remediation Projects This permit is intended to authorize most stormwater discharges from mine-waste remediation projects. This permit contains additional SWMP requirements for remediation projects. These are detailed at Part I.C of the permit, and summarized at VI.B.2 below. The Division foresees three general cases where permittees will use these provisions: 1. Inactive mine sites where the permittee begins a remediation project in order to terminate coverage under an existing. In this case, the permittee will amend their SWMP to address the remediation concerns as outlined in Part I.C.S of the permit, and proceed with remediation. Certification under this permit would be terminated when the termination criteria and other conditions listed at Part I.F of the permit are met. 2. Inactive mine sites where no previous stormwater permit coverage exists, and the owner or a third party (with permission of the owner)plans to remediate the site. In this case, the SWMP would be prepared, including the items in Part L C.5 of the permit, and the owner or third party would submit the completed permit application. After the permit certification is issued, stormwater discharges from the remediation project would be authorized. Certification under this permit would be terminated when the termination criteria and other conditions listed at Part I.F of the permit are met.