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UNITED STATES
DEPARTMENT OF LABOR
MINE SAFETY AND HEALTH ADMINISTRATION

REPORT OF INVESTIGATION

Surface Nonmetal Mine
(Limestone)

Fatal Machinery Accident
November 13, 2002


Cantera Master Aggregates
Master Aggregates Toa Baja Corp.
Arenales Bajo, Isabela, Puerto Rico
Mine I.D. No. 54-00297

Accident Investigators

Juan A. P�rez
Supervisory Mine Safety and Health Inspector

Roberto Torre-Aponte
Mine Safety and Health Inspector

Armando Pe�a
Mine Safety and Health Inspector

Luis Valent�n
Mine Safety and Health Inspector

Donald T Kirkwood
Supervisory Civil Engineer


Originating Office
Mine Safety and Health Administration
Southeast District
135 Gemini Circle, Suite 212; Birmingham, AL 35209
Martin Rosta, District Manager


OVERVIEW

Julio R�os-Beauchamp, bulldozer operator, age 30, was fatally injured while working near a highwall when a large boulder fell, crushing the victim in the cab of the bulldozer.

The accident occurred because the loose material had not been removed from the highwall. The highwall had not been examined or tested for loose ground prior to persons working in the area.

R�os-Beauchamp had a total of 11 years mining experience, 18 months as a bulldozer operator at this operation. He had received training in accordance with 30 CFR Part 46.

GENERAL INFORMATION

Cantera Master Aggregates, a crushed limestone operation, owned and operated by Master Aggregates Toa Baja Corp., was located at State Road #2, km 114.9, Arenales Bajo, Isabela, Puerto Rico. The principal operating official was Ricardo Cardona, president. The mine normally operated one 10-hour shift, 5 days a week. Total employment was 22 persons.

The mine was a multiple bench quarry accessed by decline roadways. Benches were drilled and blasted. Material was loaded by front-end loader then transported by haul trucks to the primary crushing plant where it was crushed, screened, and stockpiled. The finished product was sold for construction aggregate.

The last regular inspection at this operation was completed July 24, 2002. A regular inspection was conducted following the investigation.

DESCRIPTION OF ACCIDENT

On the day of the accident, Julio R�os-Beauchamp (victim) reported to work at 7:00 a.m., his normal starting time. R�os-Beauchamp worked on the first level of the quarry until approximately 11:00 a.m., when he was instructed by Otoniel Acevedo, supervisor, to move to the second level to push and pile material near the highwall. At 1:00 p.m., Edgardo Mercado, loader operator, Christian Lorenzo and Heriberto Gonz�lez, truck drivers, arrived at the second level to begin loading the material. At about 1:45 p.m., Mercado was loading Christian's truck when he saw a boulder fall from the highwall, land near R�os-Beauchamp's bulldozer, topple over and fall on the roll-over protective structure (ROPS) of the bulldozer. Mercado went to R�os-Beauchamp and found him pinned under the collapsed ROPS. He was unable to obtain a response from R�os-Beauchamp. Lorenzo went to assist Mercado, then placed a call to management to inform them of the accident. Local emergency assistance was summoned and paramedics arrived a short time later. R�os-Beauchamp was pronounced dead at the scene. He died as a result of crushing injuries.

INVESTIGATION OF THE ACCIDENT

MSHA was notified of the accident at 2:30 p.m. on November 13, 2002, by a telephone call from Jes' s Burgos, environmental health and occupational safety administrator for Master Aggregates Toa Baja Corp., to Juan A. Perez, supervisory mine safety and health inspector. An investigation was started that day. An order was issued under the provisions of Section 103(k) of the Act to ensure the safety of the miners. MSHA's accident investigators traveled to the mine, made a physical inspection of the accident scene, interviewed employees, and reviewed conditions and work procedures relevant to the accident. MSHA conducted the investigation with the assistance of mine management and employees.

DISCUSSION
  • The accident occurred at the base of a 27-foot highwall on the second level of the quarry that extended from the upper access on the northwest to the lower area toward the southeast.


  • This highwall had been blasted 3 weeks before the accident occurred and had not been worked for about a week prior to the accident.


  • The normal production shot consisted of 30 blast-holes drilled 34 feet deep in a three-row pattern and spaced 10 feet apart. However, a new three-row trial-blasting pattern consisting of 30 holes, drilled 50 feet deep, spaced 14 feet apart, had been detonated at the highwall involved in the accident.


  • The highwall consisted of limestone that was chalky, with numerous fossils and small pockets of clay throughout. No signs of dissolution cavities could be seen in the area of the failed highwall. The limestone in the upper third of the highwall appeared harder than the limestone in the lower two-thirds. This was evidenced by a tendency for the limestone in the lower two-thirds to ravel back, creating a slight overhang and some undercutting of the harder limestone in the upper third.


  • Cracks were observed at the top of the highwall where the failure occurred. These cracks were primarily oriented parallel to the edge of the highwall, varied in length from a few feet to tens of feet, and varied in width from hairline to several inches. These cracks were found above the fall area as well as northwest and southeast of this area and resulted from the rock close to the edge of the highwall shifting toward the pit.


  • The top of the highwall, above the fall area, had not been inspected on the day of the accident. The last inspection of this area was conducted by Acevedo about a week prior to the accident when the upper level was being drilled. At that time, although cracking was observed, no large cracks were reportedly seen.


  • The bulldozer involved in the accident was a Komatsu D-155-A, serial number 30720, manufactured in 1979. It weighed about 85,000 pounds. It was equipped with a four-post rollover protective structure (ROPS) that was cantilevered forward, beyond the front support posts, providing falling object protection to the front of the cab. The cab of the bulldozer was not completely enclosed.


  • The ROPS was manufactured by Medford Fabricating, CSC, Inc., Medford, Oregon, and was fitted with a plate that stated that the ROPS was certified for in excess of 93,000 pounds gross vehicle weight. The ROPS serial number was NH210.


  • The bulldozer was pushing broken rock into three piles. The CAT 988-B front-end loader was working on the bench loading two Euclid R-35 (35 ton) haul trucks, which were cycling back and forth between the bench and the plant.


  • At the time of the accident, the bulldozer was being backed parallel to the highwall and was approximately 8 to 10 feet from the base of the wall.


  • The boulder that struck the bulldozer was estimated to be approximately 14-1/2 feet long, 6 feet wide and 6 feet high. The volume of the boulder was estimated to be about 380 cubic feet and it was estimated to weigh 23.4 tons, based on a unit weight of the intact limestone of 123 pound per cubic foot (pcf).


  • The impact force of the boulder rolling onto the ROPS could not be determined; however, the impact force of it rolling onto the dozer would likely be much greater than the equivalent gross vehicle weight of the dozer and of the ROPS certification load.


  • Considerably more material fell from the highwall than just the boulder that struck the dozer. The volume of broken rock which fell, in addition to the large boulder, was estimated at approximately 45 cubic yards and included rock from the entire 27 feet of the highwall.


  • Weather on the day of the accident was clear with the temperature in the eighties.
  • ROOT CAUSE ANALYSIS

    A root cause analysis was conducted. Causal factors were identified that could have averted the accident or mitigated the severity of the accident.

    Causal Factor: The dozer was operating parallel to, and about 10 feet away from, the base of the highwall.

    Corrective Action: A procedure should be established for equipment working at the base of a highwall. The procedure should require that equipment should not be operated parallel to the highwall, close to the base. The equipment should be positioned perpendicular to the highwall. If is necessary for equipment to work parallel to a highwall, the distance from the base of the highwall should be determined by the height of the wall and the location of the equipment operator when performing work.

    Causal Factor: The highwall and the areas above the highwall had not been examined for unsafe conditions prior to work being performed.

    Corrective Action: A policy should be established that requires a responsible management person to examine each highwall, prior to work being performed, to identify ground conditions that pose hazards. Corrective action should be taken and work cycle procedures should be discussed before work is performed.

    Causal Factor: Highwall was undercut, allowing overhanging material in the area where work was being performed.

    Corrective Action: A procedure should be developed that addresses actions to be taken when a highwall has become undercut. This procedure should include guidelines for safely performing work beneath the highwall as well as safe procedures for working on top of the highwall. Consideration should be given to modifying drilling, blasting, and mining procedures to eliminate or reduce undercutting and back break at the top of the highwall.

    CONCLUSION

    The cause of the accident was the failure to remove the loose material from the highwall prior to persons being assigned to work in the area. Failure to inspect the highwall for loose material prior to beginning work contributed to the cause of the accident.

    Root causes identified during the investigation include the following: Failure to train or instruct equipment operators on the hazards of operating equipment parallel to a highwall and failure to develop a procedure for safely handling a highwall when the upper portion has become undercut.

    VIOLATION

    Order No. 7798589 was issued on November 13, 2002, under the provisions of Section 103(k) of the Mine Act:
    A fatal accident occurred at the quarry on November 13, 2002, when the operator of a bulldozer, Komatsu D-155-A, was crushed by material that fell from the highwall. This order is issued to assure the safety of all persons at this operation and prohibits any work in the affected area until the area can be returned to normal operations as determined by an authorized representative of the Secretary of Labor. The mine operator shall obtain prior approval from an authorized representative of the secretary for all actions to recover and/or restore operations to the affected area.
    This order was terminated on December 12, 2002. The mine operator removed all the overhanging material and the area is safe to resume normal operation.

    Citation No. 7798760 was issued on November 14, 2002, under the provisions of Section 104(a) of the Mine Act for violation of 30 CFR 56.3401:
    On November 13, 2002, a bulldozer operator was fatally injured when he was stockpiling material from a previously blasted area in the quarry. Unconsolidated material, containing large boulders, struck the bulldozer causing two columns of the ROPS structure and roof of the dozer to collapse, crushing the victim. Persons experienced in examining and testing for loose ground had not adequately inspected the area prior to work being performed.
    This citation was terminated on December 12, 2002. Persons experienced in examining and testing for loose ground were adequately inspecting the quarry area prior to work being performed.

    Citation No. 7798761 was issued on November 14, 2002, under the provisions of Section 104(a) of the Mine Act for violation of 30 CFR 56.3200:
    On November 13, 2002, a bulldozer operator was fatally injured when he was stockpiling material from a previously blasted area in the quarry. Unconsolidated material, containing large boulders, struck the bulldozer causing two columns from the ROPS and roof of the dozer to collapse, crushing the victim. Loose ground had not been taken down or supported before work was permitted in the area.
    This citation was terminated on December 12, 2002. All loose ground in the area had been removed.

    Related Fatal Alert Bulletin:
    Fatal Alert Bulletin Icon FAB02M38




    APPENDIX A


    Persons Participating in the Investigation

    Master Aggregates Toa Baja Corp.
    Jes' s Burgos ............. environmental safety and occupational health adm.
    Jeffrey Albrecht ............. plant manager
    Otoniel Acevedo ............. supervisor
    Mine Safety and Health Administration
    Juan A. P�rez ............. supervisory mine safety and health inspector
    Roberto Torres-Aponte ............. mine safety and health inspector
    Armando Pe�a ............. mine safety and health inspector
    Luis Valent�n ............. mine safety and health inspector
    Donald T. Kirkwood ............. supervisory civil engineer
    APPENDIX B

    Persons Interviewed

    Master Aggregates Toa Baja Corp.
    Jeffery Albrecht ............. plant manager
    Otoniel Acevedo ............. supervisor
    Edgardo Mercado ............. front-end loader operator
    Christian Lorenzo ............. truck driver