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COLORADO DEPARTMENT OF PUBLIC HEALTH & ENV/RONMEM -Water Quality Control Division Rationale -Page 3 Permit No. COR-040000 !V. STORMWATER DISCHARGES ASSOCIATED WITH MINING OPERATIONS The stormwarer 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 mines) which have individual CDPS permits for discharge of process waters. A. Tvoes 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 (S/C) Code 10 -Metal Mining and Milling, at sires 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 meta[ mining or milling sire that are not already subject to effluent limitations under 40 CFR 440. Those previously urscontrolled 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 srormwater and process water at a mine site. This permit may also 6e used to cover existing discharges composed entirely of stormwater from any other metal or coal mining operations that are currently covered by an indi4idua! CDPS permits for discharge of process water. At the time of reissuarsce or amendment of the individual CDPS permit, terms and limitation from both permits may be combined into a new individual permit. Table 1 presents the categories of the mining industry and their COPS Stormwater permit coverage. The Division intends ro continue its practice to cover only one area with each permit certification. As long as the operations or inactive mines are comiguous, 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 obtairsed for the disposal site. B. Mine-Waste Remediation Proiects This permit is intended to authorize most stormwater discharges from mine-waste remediation projects. There are numerous inactive mirse sites located throughout the State that may undergo remediation operations to reduce impacts to water quality, to relieve the obligation for permit coverage, or to return land to a different land use. These types of sites and their stormwater discharges were not specifically addressed in the preceding version of this permit. This permit has been revised to address the special considerations of these types of operations. This permit now 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 thesc provisions: Inactive mirse sites where the permittee begins a remediation project in order to terminate coverage under an existing. /n 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. Inactive mine sites where no previous stormwater permit coverage exists, and the owner or a third parry (with permission of the owner) plans to remediate the site. In this case, the SWMP would be prepared, including the items in Pan I.C.S of the permit, and the owner or third parry 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 6e terminated when the termination criteria and other conditions listed at Part I.F of the permit are met.