| U.S. Department of
Labor |
Mine Safety and Health Administration 1100 Wilson Boulevard Arlington, Virginia 22209-3939 |
 |
| EFFECTIVE DATE: 10/14/2010 | EXPIRATION DATE: 03/31/2012 |
PROCEDURE INSTRUCTION LETTER NO. I10-V-16
FROM: KEVIN G. STRICKLIN
Administrator for
Coal Mine Safety and Health
SUBJECT: Accumulation of Combustible Materials and Rock Dust
Scope
This Procedure Instruction Letter (PIL) applies to Coal Mine Safety and Health (CMS&H) enforcement personnel.
Purpose
This PIL provides instruction for enforcement personnel on accumulation of combustible materials and rock dust. An Emergency Temporary Standard (ETS) for Maintenance of Incombustible Content of Rock Dust was published on September 23, 2010. The ETS was effective upon publication. Each mine operator must comply with the ETS by October 7, 2010, for newly mined areas, and November 22, 2010, for all other areas of the mine. This PIL provides instruction for enforcement personnel for implementing this ETS and taking spot rock dust samples.
Procedure Instructions
District personnel should review the mine operator's program and the enforcement history for regular cleanup and removal of accumulations of coal and float coal dust, loose coal, and other combustibles.
Section 75.400, regarding accumulation of combustible materials, requires that coal dust, including float coal dust deposited on rock-dusted surfaces, loose coal, and other combustible materials must be cleaned up and not permitted to accumulate in active areas of underground coal mines, or on diesel-powered and electric equipment therein. Section 75.400 is applicable to all underground coal mines, including anthracite coal mines.
Section 75.400-2, regarding the cleanup program, requires mine operators to establish and maintain a program for regular cleanup and removal of accumulations of coal and float coal dusts, loose coal, and other combustibles. Section 75.402, regarding rock dusting, requires mine operators to apply rock dust in sufficient quantities to all areas of an underground coal mine to within 40 feet of working faces, unless underground areas are too wet or too high in incombustible content to propagate an explosion or the areas are inaccessible or unsafe to enter. This would include all crosscuts that are less than 40 feet from a working face.
Section 75.403, regarding maintenance of incombustible content of rock dust, as revised by the ETS, requires bituminous mine operators to apply and maintain rock dust so the total incombustible content (TIC) of combined coal dust, rock dust, and other dust will be maintained at 80 percent in all accessible areas of a coal mine. Where methane is present in an aircourse, the TIC must be increased by 0.4 percent for each 0.1 percent of methane.
If mine operators allow coal, float coal dust, and other combustible materials to accumulate in active workings and on equipment in the mine, or if the TIC of the combined coal dust, rock dust, and other dust in any area of the mine does not meet the quantities required by the ETS, inspectors should take appropriate enforcement action.
Selective Spot Sampling
During regular inspections, MSHA inspectors should continue to sample the incombustible content as required by MSHA's existing sampling policy and procedures for collecting rock dust samples, including sampling to within 50 feet of the tailpiece. In addition, inspectors should take selective spot samples in areas that were rock dusted prior to September 23, 2010, to determine whether the mine operator is maintaining the 80 percent TIC requirements of the ETS. Inspectors should also conduct selective spot sampling in immediate return entries, especially longwall tailgate entries, and areas containing seals. Inspectors should begin spot sampling near the active faces and in areas that contain ignition sources, such as conveyor belt drives and conveyor belt entries because these areas pose the greatest potential for methane and coal dust explosions. Inspectors need to identify the spot samples in the same manner as samples collected under the existing sampling policy and use the same mailing procedures.
When a violation of 30 C.F.R. §§ 75.400, 75.402, or 75.403 is found, abatement should be set at the shortest reasonable time after careful evaluation of conditions on a mine-by-mine basis, including whether the mine liberates large volumes of methane gas or has a history of methane ignitions. If an operator fails to totally abate within the specified time, a Section 104 (b) Order of Withdrawal should be issued.
If a mine operator has repeat violations of §§ 75.400, 75.402 or 75.403, inspection personnel should discuss the adequacy of the cleanup program with the mine operator and consider requiring the use of more effective methods for controlling and maintaining the incombustible content of the combined coal dust, rock dust, and other dust along with elevated enforcement actions. Inspection personnel should also consider changes to the cleanup program which would require the use of bulk dusters, trickle dusters or high-pressure rock dusting machines to continuously rock dust the areas downwind of belt transfers, the returns of active sections, the tailgates of longwalls and the bleeder entries.
Background
MSHA's analyses of rock dust samples, sampling records, and enforcement data, indicate that some underground coal mine operators are allowing combustible materials or coal dust to accumulate and are not applying rock dust in all required areas. Also, some operators are not maintaining the required levels of rock dust application under 30 C.F.R. §§ 75.400, 75.400-2, 75.402, and 75.403.
Authority
The Federal Mine Safety and Health Act of 1977, as amended, 30 U.S.C. § 801 et seq.;
30 C.F.R. §§ 75.400, 75.400-2, 75.402 and 75.403.
Internet Availabilityu>
This PIL may be viewed on the Internet by accessing MSHA's home page at (www.msha.gov), choosing "Compliance Info" and "Procedure Instruction Letters."
Issuing Office and Contact Person
Coal Mine Safety and Health, Safety Division
Michael G. Kalich, (202) 693-9714
E-mail: kalich.michael@dol.gov
Distribution
MSHA Program Policy Manual Holders
