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Northeastern District
Metal and Nonmetal Mine Safety and Health

Accident Investigation Report
Surface Nonmetal Mine

Fatal Explosives Accident

Explo-Tech Incorporated
ID No. 36-02362-W21
Miller Quarries
Division of Miller & Son Paving Incorporated
Rushland, Bucks County, Pennsylvania

May 8, 1996


Dennis A. Yesko, Supervisory Mine Safety and Health Inspector

Charles J. Weber, Mine Safety and Health Inspector
Special Investigator


C. Okey Reitter, Jr., Supervisory Mine Safety and Health Inspector

Mine Safety and Health Administration
Northeastern District Office
230 Executive Drive, Suite 2
Cranberry Township, Pennsylvania 16066-6415

James R. Petrie, District Manager


Gerald T. Little, truck driver/laborer, age 31, was fatally injured at approximately 9:20 a.m. on May 8, 1996, when a non-electric down-hole primer he was assembling detonated prematurely. Little was employed by Explo-Tech Inc., an independent contractor that specialized in blasting. He had a total of 20 months mining experience as a truck driver/laborer with this contractor, 17 months of which included assisting the blaster in charge in assembling primers and loading holes.

Little had last received annual refresher training on April 5, 1996, in accordance with 30 CFR Part 48. This training addressed safe handling of the various products utilized by Explo-Tech Inc., including protecting explosives from impact.

MSHA was notified at 10:00 a.m., the day of the accident, by Joseph Johnson, Jr., quarry superintendent at Miller Quarries, the site of the accident. An accident investigation was started the same day.

Miller Quarries, an open pit crushed stone operation, owned and operated by Miller & Son Paving Inc., was located in Rushland, Bucks County, Pennsylvania. The principal operating official was Joseph Johnson, Jr., quarry superintendent. The plant was normally operated one 9-hour shift per day, 5 days per week, and a �-day maintenance shift on Saturday. A total of 15 persons was employed.

Explo-Tech Inc., was owned and operated by Explosive Technologies International (ETI), Wilmington, Delaware, and was contracted to conduct blasting at Miller Quarries Inc. The principal operating official was Sherman Hayes, south east area sales manager-explosives.

Argillite, a sedimentary rock, was mined by drilling and blasting multiple benches. Broken stone was loaded by a front-end loader into trucks and hauled to the processing plant where it was crushed and sized. The finished product was stockpiled and primarily sold as construction aggregate.

The last regular inspection of Miller Quarries Inc., was completed on November 2, 1995. Another regular inspection was conducted on June 19, 1996, in conjunction with this investigation.


At the time of the accident, Little was assembling a non-electric down-hole primer at the back of the explosives truck. The primer, which prematurely detonated, consisted of either a Detaslide MS 450 or MS 500 delay detonator, inserted into a 1-pound, HDP-1 cast booster. The Detaslide detonators contained a Remington .22 caliber rimfire casing held in an "L" shaped plastic body. The MS 450 delays were manufactured on February 6, 1991, and the cast boosters were manufactured on April 1, 1996, both by Ensign-Bickford. The MS 500 delays were manufactured on April 2, 1991, by Dupont. Detaslide , Detaline detonating cord was used as the downline initiation source for the detonators.

The manufacturer's product literature shipped with the detonators and cast boosters instruct the user to fully insert the Detaslide detonator into the capwell of the cast booster when assembling a primer. Also included was a warning to never force or attempt to force a detonator into explosive material.

The rear of the 1978 Mack, R model explosives truck, V.I.N. R685T7216, was provided with a bumper approximately 12 inches wide, extending the width of the truck. This bumper served as a work platform for loading/unloading explosives, and for assembling primers. It was constructed of a 2-by 10-inch oak board, covered with a layer of -inch steel diamond plate, on top of which was a layer of -inch aluminum diamond plate. One hole was blown through the left side of the bumper. The opening measured approximately 10 inches through the aluminum plate, and 5 inches in diameter through the steel plate and oak board.

Little was found approximately 10 feet from the rear of the truck. He had sustained massive injures to the abdominal area of the body, and the upper extremities. The pattern of damage to the bumper, and of the injuries to Little, indicated that he was holding a primer with his left hand against the top, left side of the bumper when it detonated.

On the rear of the explosives truck there were five bags of emulsifier, numerous starters and surface delays, one damaged booster, and the remnants of several boosters damaged in the explosion. Some other damaged explosive materials were found approximately 75 feet from the truck. A wood handled steel knife, used to cut the Detaline cord and slit bags of ammonium nitrate fuel oil (ANFO), was found on the ground approximately 10 feet from the victim. A lead weight, normally attached to a plastic measuring tape, used to measure the depth of the boreholes, was also found on the ground near the rear of the truck. Many small pieces of the measuring tape were found scattered about the scene.

The knife and lead weight were examined after the accident to determine if either may have been used by Little to seat the detonator in the booster. The preliminary results of the examination, however, were inconclusive. Two of Little's co-workers stated that about 1 year prior to the accident, they had seen Little tap on a detonator with a knife to seat it in a booster. At that time, both employees said they had separately cautioned Little about this practice, and that Little had told them he would not do it again. Neither employee had informed their supervisor of Little's actions.

Examination of the detonators and cast boosters found at the accident site, and at the contractor's explosive magazine, revealed that the detonators easily fit into the capwell in all the boosters examined, with the exception of one booster damaged by the explosion. Explo-Tech Inc. also provided additional Detaslide detonators and HDP cast boosters for further examination and testing by MSHA. Several of these MS 450 Detaslide detonators subsequently provided were found to be slightly longer than the others examined. Sherman Hayes, sales manager, and Ernest Leffler, blaster-in-charge, stated that about 9 years ago they had experienced an instance where four cast boosters in one case had been defective. The detonators could not be inserted because of malformed capwells when the boosters were cast. The defective boosters were not used, and were returned to the manufacturer.

MSHA also requested that the U.S. Department of Energy conduct testing of the functional sensitivity of the detonators and boosters. Preliminary results of this testing appear similar to tests conducted by the explosives manufacturer in 1985 and 1987, with the results indicating that the Detaslide detonators were not unusually sensitive to impact.

There were no signs of lightning in the area at the time of the accident.


On the day of the accident, Gerald Little, victim, reported to work at approximately 6:30 a.m., his normal starting time. He unloaded explosives from the explosives truck until two of his co-workers and supervisor arrived.

After unloading the truck, Little assisted Ernest Leffler, blaster-in-charge, and H. Craig Keck, blaster, in loading holes with primers and ANFO at the west end of the No. 5 production bench. Little then assisted Cliff Wood, truck driver, in repositioning the dewatering truck on the bench, after which Little proceeded toward the rear of the explosives truck.

At approximately 9:20 a.m., Leffler, Keck and Wood reported they heard an explosion. Leffler said he looked up, saw a flash by the explosives truck, and realized that a premature detonation had occurred. He ran around the driver's side of the truck and found Little lying on the ground about 10 feet from the rear of the truck. Little had sustained massive injuries and was killed instantly. Leffler drove to the mine office where he reported the accident and 911 was called. A local ambulance responded to the call. Little was pronounced dead at the scene by the county deputy coroner.


Evidence indicated that the victim was assembling a primer, consisting of a Detaslide detonator and an HDP-1 cast booster, on the rear bumper of the explosives truck when it prematurely detonated. The detonation was apparently caused when the primer assembly was subjected to impact. Co-workers stated, that on two prior occasions, they had seen the victim tapping on a detonator with a knife to seat it in a booster.


The following violations were issued during the investigation:

Order No. 4441176
Issued on May 8, 1996, under the provisions of Section 103(k) of the Mine Act to ensure the safety of persons during the recovery operations and until the affected areas of the mine could return to normal.

This order was terminated on May 10, 1996.

Citation No. 4439688
Issued on August 5, 1996, under the provisions of Section 104(a) of the Mine Act for violation of 30 CFR 56.6302(b):

A premature detonation of explosives occurred at this operation on 5/8/96, resulting in a fatal injury to Gerald T. Little, who was employed by Explo-Tech Inc., an independent contractor. The victim was assembling a detonator and cast booster to form a down-hole primer when the explosion occurred. It was stated by witnesses that Little was seen tamping a detonator into a booster on at least two occasions. The primer was not protected from impact during its assembly.

This citation was terminated on August 16, 1996. Explo-Tech retrained all its employees on the need to protect explosives from impact. Each employee signed a copy of the training received, and a copy of the company policy was provided to MSHA.

Dennis A. Yesko
Supervisory Mine Safety and Health Inspector

Charles J. Weber
Mine Safety and Health Inspector, Special Investigator

C. Okey Reitter, Jr.
Supervisory Mine Safety and Health Inspector

Approved by:

James R. Petrie, District Manager

Related Fatal Alert Bulletin:
Fatal Alert Bulletin Icon [FAB96M17]