OAR 340-043-0000: Purpose and Policies

(1) The purpose of these rules and guidelines is to prevent water pollution and protect the quality of the environment and public health in Oregon, consistent with the policies of ORS 468B.015 and 468B.020, by requiring application of all available and reasonable method for control of wastes and chemicals relative to design, construction, operation, and closure of mining operations which use cyanide or other toxic chemicals to extract metals or metal-bearing minerals from the ore and which produce wastes or wastewaters containing toxic materials. (2) The following policies are established to provide further guidance regarding the level of environmental protection these rules are intended to achieve: (a) Liner, leak detection and leak collection systems (systems) are necessary for heap leach pads, solution ponds, and tailings facilities to assure that any leak will be detected before toxic materials escape from the liner system and are released to the environment. For purposes of these rules, the environment is considered to begin at the bottom of the last liner. These systems shall assure that a leak is found, and that sufficient time is available to allow for the repair of the leak and cleanup of any leaked material before there is a release to the environment. Natural conditions, such as depth to groundwater or net rainfall, shall be considered as additional protection but not in lieu of the protection required by the engineered liner system; (b) The toxicity of mill tailings and the potential for long-term cyanide and toxic metals release from mill tailings shall be reduced to the greatest degree practicable through removal, reuse, or destruction of chemical solutions prior to placement of tailings in the tailings disposal facility; (c) The closure of heap leach pads and tailings disposal facilities shall prevent future release to the environment of residual potentially toxic chemicals contained in the facility.