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Hearings on Crandall Canyon mine Part XXV


Senator Kennedy Senate report released on mine disaster

Technical Analyses of Retreat Mining

The Secretary, in consultation with NIOSH and the Safety and Health Technology Center, should promulgate regulations establishing uniform methods, requirements and parameters for technical analyses of retreat mining, including:

• A list of acceptable software or other analytical tools (such as the ARMPS or LAMODEL software packages) that NIOSH deems of sufficient quality to be accepted by the Agency in mine plan submissions;

• A list of approved methods of operating or applying these tools. Such approved methods should (a) specify acceptable parameters and other inputs to be used (or ranges for those parameters or inputs) and (b) where parameters and other inputs are based on site-specific data, establish approved techniques for determining such site-specific data;

• Minimum stability factors (for both barrier pillars and production pillars), calibrated for various depths, for retreat mining plans.

The Secretary should direct all Agency personnel to reject retreat mining plans where pillar stability factors are not equal to or greater than these minimum stability factors, unless the mine operator submits a petition under section 101(c) of the Federal Mine Safety and Health Act of 1977, using site-specific data collected through approved techniques and the petition is approved by the Safety and Health Technology Center as not exposing miners to unusual dangers.

In consultation with the Safety and Health Technology Center and NIOSH, MSHA should formulate a Roof Control Handbook (similar to the MSHA Ventilation Review.

For example, item 4 under "Management System Controls" in section V.G-4 of the Program Policy Manual should be revised to include a requirement that MSHA re-run software or other engineering tools used to assess mine safety.

ARMPS (Analysis of Retreat Mining Pillar Stability) and LAMODEL (Laminated Model) are displacement discontinuity computer models used by mine engineers to calculate mine stability factors and measure stress and displacement.

NIOSH distinguishes between "'production pillars' that are within the mining panel" and "'barrier pillars' that isolate individual panels from adjacent mined out areas." (Handbook) that contains guidelines for MSHA personnel charged with reviewing roof control plans and amendments.

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