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UNITED STATES
DEPARTMENT OF LABOR
MINE SAFETY AND HEALTH ADMINISTRATION

REPORT OF INVESTIGATION

Surface Nonmetal Mine
(Limestone)

Fatal Electrical Accident
September 16, 2002

Plaza Materials Corporation
Plaza Materials Corporation
Crystal Springs, Pasco County, Florida
Mine I.D. No. 08-00956

Accident Investigators

Steve J. Kirkland
Supervisory Mine Safety and Health Inspector

Joel B. Richardson
Mine Safety and Health Inspector

Stephen B. Dubina, Jr.
Electrical Engineer

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

OVERVIEW

Leon R. Davison, welder, age 43, was fatally injured on September 16, 2002, when he contacted an energized welding electrode.

The accident occurred because the victim was welding in a confined space while lying on a metal screen, when the electrode contacted his wet clothing. Davison had a total of 22 years welding experience with two years, two months mining experience at this operation. He had received training in accordance with 30 CFR Part 46.

GENERAL INFORMATION


Plaza Materials Corporation, a crushed limestone operation, owned and operated by Plaza Materials Corporation, a subsidiary of Yonkers Contracting Company, was located at 41150 Yonkers Boulevard, Zephyrhills, Pasco County, Florida. The principal operating official was Dain Williams, general manager. The mine normally operated one production ten-hour shift a day, five days a week. An excavating crew worked the two ten-hour shifts, five days a week and a maintenance crew worked night shift, five days a week and Saturdays. Total employment was 29 persons.

After overburden was stripped, limestone was drilled, blasted, excavated with draglines and stockpiled in windrows to dry. The material was then hauled by truck to the plant where it was crushed, washed, screened, sized and stockpiled. The final product was sold for use in road construction and to make concrete block and concrete mix.

The last regular inspection at this operation was completed July 2, 2002. A regular inspection was conducted following the investigation.

DESCRIPTION OF ACCIDENT

On the day of the accident, Leon Davison (victim) reported to work at 5:00 p.m., his normal starting time. He was instructed to replace the wear plate on the triple deck screen at the screen tower.

Davison went to the screen tower and met Donald Thomas, maintenance foreman, who had taken the measurements for the wear plate. Davison then cut the piece of metal to replace the plate. He returned to the screen tower and started welding the piece of metal into place. At about 6:30 p.m., Wayne Lohmeyer, maintenance helper, was working below the screen tower when he heard Davison call out to him. Lohmeyer answered back and received no response. He went up on the screen tower to check on Davison and found him lying on the screen with the welding electrode in his hand, against his chest. Lohmeyer called to Thomas who was near the screen tower. Thomas arrived at the scene, then checked Davison for a pulse. Lohmeyer stayed with Davison while Thomas drove to the office and called 911 for assistance.

The emergency rescue unit arrived a short time later and was unable to detect a heartbeat. Davison was pronounced dead at the scene due to electrocution.

INVESTIGATION OF THE ACCIDENT

MSHA was notified of the accident at 8:05 p.m., on the day of the accident by a telephone call from the dispatcher for Pasco County Sheriff's Department to Harry Verdier, assistant district manager. 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 triple deck shaker screen of the No. 2 screening plant. The screen measured about 6 feet by 20 feet and was equipped with three different size wire mesh screens. The top screen, where the victim was working, had one-inch by one-inch openings. The two lower screens had smaller openings.


  • Stone was fed onto the shaker screen from two conveyor belts. The belts measured 24 inches and 30 inches wide. Clearances between the conveyor belts and the top of the screen were 18 inches and 15 inches, making it difficult for a person to weld the plate into place.


  • Davison was found lying on the top screen, partially positioned under the conveyor head pulleys, near the plate he was welding. He was found lying on his back, with the welding electrode across his chest. Burn marks on the left side of Davison's chest were consistent with electrical shock.


  • Rock was discharged from the conveyor belts against two deflector plates and then down onto the wear plate. The wear plate, which measured � inch by 11 inch by 6 foot, was a metal strip installed at the top of the shaker screen to take the abrasive wear and prevent the screens from prematurely wearing out. It was installed so that it could easily be changed out.


  • The diesel-powered 400 amp Miller Big Blue 400D welder provided DC current for welding. The open circuit voltage at the accident site, between the ends of the leads, measured 79.5 volts DC, while the welder was running. The voltage across the lead lugs at the welder measured 79.6 volts. The spring was missing from the spring loaded ground clamp and the clamp was attached to the wire screen by sticking the ends of the clamp through the one-inch openings in the screen and wedging the clamp. The grounding lead had been damaged and several wires were severed; however, ground continuity was adequate to operate the welder. Upon inspection of the welder, no safety defects were observed.


  • Prior to the accident, the victim had welded the right side of the wear plate solid. Two support shims under the plate had been welded and welding had begun on the third shim.


  • A new 1/8-inch 7018 welding rod had been installed in the electrode and about half of the flux was broken off the rod. It could not be determined if the flux was broken before or after the accident.


  • Welding gloves were found at the accident site and the supervisor stated that he had removed one glove to check for a pulse.


  • A burn place on the victim's right side indicated that he was partially on his side or turned onto his back when he received the electrical shock, possibly while attempting to change the welding rod.


  • Weather on the day of the accident was about 95 degrees with high humidity. Light rainfall had occurred just prior to the accident. The victim's clothing was wet.


    • CONCLUSION

    The cause of the accident was the victim contacting the energized welding electrode. The root causes were the failure to utilize dry insulating material while welding when lying on steel, and failure to wear dry clothing.

    VIOLATION

    Order No. 6067379 was issued on September 16, 2002, under the provisions of Section 103(k) of the Mine Act:
    A fatal accident occurred at this operation on September 16, 2002, when a welder came in contact with the energized electrode while welding at the top of the triple deck shaker screen. This order is issued to assure the safety of all persons at this operation 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 September 18, 2002. Maintenance employees were trained in proper procedures to be followed when welding in confined spaces.

    Related Fatal Alert Bulletin:
    Fatal Alert Bulletin Icon FAB02M27



    APPENDIX A

    Persons Participating in the Investigation

    Plaza Materials Corporation
    Dain Williams ......... general manager
    Brenda Spivey ......... office manager
    Dennis Riley ......... day shift supervisor
    Donald Thomas ......... maintenance supervisor
    Wayne Lohmeyer ......... maintenance helper
    St. Paul Insurance Company
    Flickey Homan ......... claim account specialist workmans' compensation
    Pasco County Sheriff's Department
    Delia Carter ......... deputy
    Harmon Campbell ......... deputy
    Mine Safety and Health Administration
    Steve J. Kirkland ......... supervisory mine safety and health inspector
    Joel B. Richardson ......... mine safety and health inspector
    Stephen B. Dubina, Jr. ......... electrical engineer


    APPENDIX B
    Persons Interviewed

    Plaza Materials Corporation
    Donald Thomas ......... maintenance supervisor
    Wayne Lohmeyer ......... maintenance helper