Section 58.01.13.201 - DESIGN CRITERIA FOR LEACH PADS AND OTHER NONIMPOUNDING SURFACES THAT CONTAIN AND PROMOTE HORIZONTAL FLOW OF PROCESS WATERPlans and specification for leach pads and other nonimpounding surfaces that temporarily contain, not impound, process water and promote the horizontal flow of process water must provide for all of the following.
01.Minimal Hydraulic Head. Process water is limited to twelve (12) inches or less hydraulic head pressure on the liner systems.02.Engineered Liner System. In addition to meeting the general liner requirements in Subsection 200.06.b., the engineered liner system plans and specifications are to provide for geomembrane liners with a minimum thickness of eighty (80) milli-inches (two point zero (2.0) mm) or equivalent liners approved by the Department.a. If leach pads or other non-impounding surfaces are located above areas where ground water is considered near the surface pursuant to Subsection 200.06.a.iii., the Department may require a liner system with a higher level of engineered containment.b. When a material or system that provides hydraulic relief is installed, beneath a single liner, including, but not limited to, sand, French drains and geotextiles, regardless of the intent of its design, it is to function as a leak detection system and include a means for recovering process water.c. Depending on the methods and materials used for their construction, the Department may require all open channels that routinely transport process water to be traced by a leak detection system.03.Ore Loading Procedures. Procedures for loading ore onto the leach pads that minimize tensile stresses in the containment liners that may result in failure of the liners.04.Monitoring. Monitoring points that will provide for early detection of any discharge.05.Process Water Containment. Where appropriate, process water containment calculations at the leach pad perimeter should include the potential for drainage constrictions, including constrictions due to talus or washouts at the ore pile toe. Ore pile setbacks from the leach pad perimeter should be calculated based on local climatic conditions, ore properties, and site specific operating conditions. Solution collection ditches in which the liner is contiguous with the leach pad may be used to satisfy perimeter containment requirements.Idaho Admin. Code r. 58.01.13.201