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Doc Date:1 211 112 0 0 1 III IIIIIIIIIIIII III SI~ 4.07 SEALING OF DRILLED HOLES AND UNDERGROUND OPENINGS 4.07.1 GENERAL REQUIREMENTS With the exception of drillholes completed as either water supply wells or monitoring wells, all exploration drillholes, boreholes, and exposed underground openings will be plugged and sealed in order to prevent acid or toxic drainage, minimize disturbance to the prevailing hydrologic balance and ensure the safety of animals, persons and equipment within the permit and adjacent areas. 4.07.2 TEMPORARY SEALING Drillholes completed as water supply or monitoring wells will be cased to just above the ground surface and capped. No other temporary sealing measures are proposed since capping of wells will adequately address any potential concerns and will facilitate access to the wells when needed. As part of the hydrologic monitoring program, the condition of well installations including surface casing and caps will be inspected on a regular basis. Any damage will be noted and repairs will be completed on a timely basis. 4.07.3 PERMANENT SEALING Any drillholes not completed as monitoring wells will be sealed and abandoned. Abandonment will involve establishing a cement grout seal extending approximately 20 feet above and below any water producing zones(s), backfilling the remainder of the drillhole with cuttings to within approximately 20 feet of the collar, cementing an interval from the top of the backfill to approximately three (3) feet below the surface, placing a metal fence post as a permanent marker, and backfilling the remainder of the hole with soil material. • When mining is completed, the mine portals will be sealed to prevent access. Sealing will involve fabrication of concrete block walls located a minimum of 25 feet inby the portal openings. The outside surface of the block walls will be sealed with an MSHA approved sealant to prevent 4.07-1