PURPOSE: This rule sets forth the requirements for casing and sealing of exposed underground holes pursuant to sections 444.810, 444.855.2(3)(iii), and 444.860, RSMo.

1. (1) General Requirements. Each exploration hole, other drillhole or borehole, shaft, well, or other exposed underground opening shall be cased, lined, or otherwise managed as approved in the permit and plan to prevent acid or other toxic drainage from entering ground and surface waters, to minimize disturbance to the prevailing hydrologic balance, and to ensure the safety of people, livestock, fish, and wildlife, and machinery in the mine plan and adjacent area. Each exploration hole, drillhole or borehole, or well that is uncovered or exposed by mining activities within the permit area shall be permanently closed, unless approved for water monitoring or otherwise managed in a manner approved in the permit and plan. Use of a drilled hole or monitoring well as a water well must meet the provisions of 10 CSR 40-3.200(13) and those of the Wellhead Protection Section, Division of Geology and Land Survey at 10 CSR 23 Chapter 6. This section does not apply to holes drilled and used for blasting in the surface area affected by underground operations.

2. (2) Temporary Casing and Sealing of Underground Openings.

   1. (A) Each mine entry, which is temporarily inactive but has a further projected useful service under the approved permit application, shall be protected by barricades or other covering devices, fenced and posted with signs to prevent access into the entry and to identify the hazardous nature of the opening. These devices shall be periodically inspected and maintained in good operating condition by the person who conducts the underground mining activities.
   2. (B) Each exploration hole, other drillhole or borehole, shaft, well, and other exposed underground opening which has been identified in the approved permit and plan for use to return underground development waste, 10 CSR 40-3

coal processing waste to underground workings, or to be used to monitor groundwater conditions shall be temporarily sealed until actual use.

1. (3) Permanent Casing and Sealing of Underground Openings. When no longer needed for monitoring or other use approved in the permit and plan, upon a finding of no adverse environmental or health and safety effects, or unless approved for transfer as a water well under 10 CSR 40-3.200(13) and those of the Wellhead Protection Section, Division of Geology and Land Survey at 10 CSR 23 Chapter 6, each shaft, drift, adit, tunnel, exploratory hole, entryway, or other opening to the surface from underground shall be capped, sealed, backfilled, or otherwise properly managed as required in the permit and plan under section (1) and 10 CSR 40- 3.200(11) and consistent with 30 CFR 75.1771. Permanent closure measures shall be designed to prevent access to the mine workings by people, livestock, fish and wildlife, machinery, and to keep acid or other toxic drainage from entering ground or surface waters.

AUTHORITY: section 444.810, RSMo 2000.* Original rule filed Aug. 8, 1980, effective Dec. 11, 1980. Amended: Filed Dec. 17, 2012, effective July 30, 2013. *Original authority 1979, amended 1983, 1993, 1995.