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<br /> <br /> <br /> 42 C1981-041 RN7 findings <br />All Refuse disposal piles; RSRDA, CRDA-1 and CRDA-2 have previously been <br />approved for Phase III bond release. CRDA-1 and CRDA-2 have been removed from <br />the permit area with the approval of TR-70. <br /> <br />V. Sealing of Drilled Holes and Underground Openings <br /> <br />The method for sealing portals is depicted in Permit Figure 14-2. The South Mine <br />Portals have been sealed with a 24” thick concrete seal, and will be backfilled with <br />approximately 100 feet of dirt backfill extending out from the concrete seals. An <br />underdrain will be installed in conjunction with final backfilling to drain portal area <br />seepage away from the portal backfill. Other mine area portal openings were <br />backfilled with a minimum of 25 feet of incombustible backfill. Long term mine <br />discharge (post reclamation) from the Roadside South Mine will be from a gravity <br />discharge pipe installed by angled drilling in the vicinity of the North Decline area <br />(Outfall 016); a back-up discharge system is provided by a portal drain installed in the <br />seal of the reclaimed Northwest Intake Portal, which allows discharge through CDPS <br />Outfall 002 via siphon tubes. Outfall 002 would only be used in the event of <br />malfunction of Outfall 016. Due to the orientation of the North Mine workings, which <br />slope away from the portal and river, and due to the elevation of the portal which is <br />above the recovered groundwater elevation, no surface discharge from the North <br />Portal Mine is projected following reclamation, and thus no provisions were made for <br />discharge from the North Mine following reclamation. <br /> <br />Exploration drill holes, boreholes, or wells not completed in an aquifer will be sealed <br />by replacing cuttings in the hole and placing a cement plug in the top of the hole from <br />ten feet down to within three feet of the ground surface. The South Fan shaft was <br />sealed in this manner in the fall of 2000. <br /> <br />If a hole is completed in an aquifer, it will be sealed by placing an approved cement <br />or sealant in the hole from the bottom to within ten feet of the ground surface, a cement <br />plug will be placed in the upper ten feet. <br /> <br />Figure 14-2 illustrates typical permanent mine seals, and Figure 14-3 depicts a typical <br />“dry hole” permanent drill hole seal. <br /> <br />In 2014 a landowner directed water from a ditch to an area of north of the “Carey pit” <br />located in Township 10 South, Range 98 West, Section 34, and South of the sealed <br />Roadside South Portals. The water “disappeared” into the ground at a rate faster than <br />would be expected with normal infiltration. In response to the disappearance of the <br />water at this point, flow was noted at the French drain at the South Portals. Once the <br />water applied in Section 34 was stopped, flow from the French drain slowed and <br />eventually stopped. Investigation of Section 34 found that an air shaft had existed in <br />the area previously that had been sealed. No records or documentation were located <br />to confirm how or when this air shaft had been sealed. SCC conducted a study of the <br />air shaft vicinity to narrow down the locale of the suspected hydrologic <br />communication between the surface and underground workings. As a result of the