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4.07 SEALING OF DRILLED HOLES AND UNDERGROUND OPENINGS <br />The Southfield Mine is in reclamation only status since operations permanently ceased <br />in 2000. EFCI commenced reclamation activities at the mine site in 2001, demolishing <br />surface facilities and sealing all mine openings. By 2001, backfilling, regrading, and <br />topsoil replacement was completed according to plans approved by the DRMS. All <br />remaining drillholes, including monitoring wells, will be sealed in accordance with <br />approved plans prior to application for final bond release of the mine site. <br />4.07.1 GENERAL REQUIREMENTS <br />With the exception of driliholes completed as either water supply wells or monitoring <br />wells, all exploration drillholes, boreholes, and exposed underground openings will be <br />plugged and sealed in order to prevent acid or toxic drainage, minimize disturbance to <br />the prevailing hydrologic balance and ensure the safety of animals, persons and <br />equipment within the permit and adjacent areas. <br />4.07.2 TEMPORARY SEALING <br />Drillholes completed as water supply or monitoring wells will be cased to just above <br />the ground surface and capped. No other temporary sealing measures are proposed <br />since capping of wells will adequately address any potential concerns and will facilitate <br />access to the wells when needed. As part of the hydrologic monitoring program, the <br />condition of well installations including surface casing and caps will be inspected on a <br />regular basis. Any damage will be noted and repairs will be completed on a timely <br />basis. <br />4.07.3 PERMANENT SEALING <br />Any drillholes not completed as monitoring wells will be sealed and abandoned. <br />Abandonment will involve establishing a cement grout seal extending approximately <br />20 feet above and below any water producing zones(s), backfilling the remainder of <br />the drillhole with cuttings to within approximately 20 feet of the collar, cementing an <br />interval from the top of the backfill to approximately three (3) feet below the surface, <br />placing a metal fence post as a permanent marker, and backfilling the remainder of <br />4.07 -1 <br />Revised 5/14/14 RN -06 <br />