On March 20, 2001, Norman Jenkins, road
construction foreman, age 38, was fatally injured when an explosion occurred
while he was melting a layer of ice from the bottom of an enclosed truck scale
pit with propane torches. The accident occurred because an open flame was
introduced into an area where flammable gases had accumulated.
Jenkins had a total of 11 years, and 10 months experience as a foreman, with the
last seven years working on scales. He had received training in accordance with
30 CFR, Part 46.
Plant No. 4, a portable crushing plant, owned and
operated by Michels Pipeline Construction, Inc., traveled to various locations
within Wisconsin. The plant had been moved to the Hamilton Hills Quarry in
Byron, Fond du Lac County, Wisconsin on March 16, 2001. The principal operating
official was Patrick D. Michels, President. The mine operated one, 11-hour
shift, five days a week. Total employment was three persons.
Limestone was drilled and blasted at the quarry by contractors. The limestone
was fed into a portable crushing plant by front-end loaders, crushed, sized, and
stockpiled. The finished products were loaded into over-the-road trucks, weighed
at the quarry's truck scales, and sold for construction aggregate.
The last regular inspection of this operation was completed on October 5, 2000.
Another inspection was conducted following this investigation.
On March 19, 2001, the day before the accident,
at approximately 4:00 p.m., Norman Jenkins (victim) was informed by John
Westerman, crushing supervisor, that the scale at the Hamilton Hill Quarry
needed to be checked because they were going to start hauling out of that
quarry.
On the following morning, Jenkins went to the Hamilton Hill Quarry at about 9:00
a.m. He went to the portable crushing plant and asked Joe Schmitt, plant
foreman, for an extra tarpaulin. He stated that he needed to get heat under the
scale to thaw out the ice. He said that he was going to use LP gas tanks with
barrel heating torches and cover the scale to retain the heat. Jenkins stated
that he would leave after it was covered, but would return later and check on
it.
Sometime between noon and 1:00 p.m., Jenkins returned to the crushing plant
where he informed Schmitt that he would use both a 20-pound and a 100-pound
propane tank with torches to produce heat. He said he would return at the end of
the day.
Jenkins returned to the mine at approximately 4:15 p.m. About 10 minutes later,
Schmitt, who was in the quarry, heard a loud explosion. He looked up toward the
truck scale and saw deck plates and debris flying into the air. He immediately
got into his truck and headed to the site. When he arrived, he saw the scale
deck plates, a 100-pound propane cylinder, a torch with a broken hose, and
tarpaulins scattered about. Jenkins' truck was covered with dust. Schmitt saw
Jenkins lying face down on the ground at the south end of the scale with one of
the scale deck plates partially covering him. He called the company dispatcher
to request emergency assistance. Westerman was on the road nearby the quarry and
arrived almost immediately. Schmitt, who was previously an EMT, and Westerman
checked Jenkins for vital signs and found none.
The County Sheriff's Department and local emergency personnel arrived a short
time later. The victim was pronounced dead at the scene by the County Medical
Examiner.
Death was attributed to multiple traumatic injuries due to an explosion.
MSHA was notified at 7:15 p.m. on March 20, 2001,
by a telephone call from A. David Stegeman, general counsel of Michels Pipeline
Construction, Inc., to Steven M. Richetta, assistant district manager. An
investigation began the same day. An order was issued pursuant to Section 103(k)
of the Mine Act to ensure the safety of miners.
MSHA's investigation team conducted a physical inspection of the accident site,
interviewed a number of persons, and reviewed procedures performed by the
victim. Management officials and employees assisted in the investigation. The
miners did not request, nor have, representation during the investigation.
?The truck scale was manufactured by the Thurman
Company of Columbus, Ohio. It was rated for 50-ton capacity and measured 10 feet
by 40 feet. It was installed in a 3-foot deep concrete pit which made it level
with the surrounding road and ground surfaces. Seven steel deck plates were
bolted to the top of the scale. The deck plates were made of 1/4-inch thick
steel with a raised checkered pattern. The deck plates weighed approximately
11.25 pounds per square foot. Six of the plates measured 10 feet by 6 feet and
weighed approximately 675 pounds each. The seventh plate, normally located in
the center of the scale, measured 10 feet by 4 feet and weighed approximately
460 pounds. The force of the explosion had broken all of the deck plates from
their bolted positions and one of the plates landed about 98 feet from the
scale.
?There was approximately a 2-1/2 inch layer of ice on the scale pit floor during
the investigation, which restricted scale movement for weighing trucks.
?A 20-pound propane gas cylinder was found in the scale pit by firefighters,
apparently blown back from its original location. The diameter of the stand ring
on the bottom of the cylinder was approximately 7-3/4 inches, matching the
diameter of the circular imprint melted in the ice layer near the center of the
pit approximately 6 feet north and east of the access hatch. There were no signs
of excess heat, such as scorching or charring, on the painted surface of the
cylinder. One very small dent was found in the cylinder.
?A 100-pound cylinder was found approximately 55 feet south of the scale. The
cylinder shutoff valve had been knocked off where the stem threads into the
cylinder head. The cylinder was laying on its side and was venting some but not
a significant volume of fuel, according to a witness who arrived approximately
three minutes after the explosion.
?Neither cylinder had signs of internal over-pressure and neither was ruptured.
?The torch and hose assemblies for both the 20-pound and 100-pound cylinders
were model WB-101, heavy duty Hotspotter burners, manufactured by Western
Enterprises of Westlake, Ohio. The assemblies included the torch, a 24-inch long
steel pipe feeding the torch (also used for a handle), and a manual shutoff
valve at the end of the pipe connected to 10 feet of propane-approved hose with
a proper connector at the other end for the propane cylinder valve. A striker
was also included. These torches are sometimes referred to as "rosebud" or
"barrel" torches.
?The torch assembly for the 20-pound cylinder was intact and still connected to
the cylinder. Emergency personnel closed both the cylinder valve and torch valve
as a precaution during the emergency response.
?The Material Safety Data Sheet (MSDS) from the propane gas supplier indicated
that the content of each cylinder was 100 percent propane, with ethyl mercaptan
to odorize.
?When full, the 20-pound cylinder would contain 20 pounds of liquified propane.
This was sufficient fuel to fill a volume approximately 6.5 times the volume of
the scale pit at the Lower Explosive Level (LEL) concentration of 2.1 percent.
?The victim had used the same method to thaw scales in the past but they were
above ground level or open on at least one side.
?The weather at the time of the accident was clear, calm, and 40 degrees
Fahrenheit.
The cause of the accident was the introduction of
a flame into an enclosed area where flammable gases had accumulated.
The root cause of the accident was management's failure to establish a safe work
procedure for this task that would have included appropriate warnings of
possible hazards. A proper task evaluation should have identified the scale pit
as a confined space.
Order No. 7841295 was issued on March 20, 2001, under the provisions of Section 103(k) of the Mine Act:
A fatal accident occurred at this operation on March 20, 2001, when an explosion occurred while a maintenance worker was in the process of melting ice from the bottom of the truck scale. This order is issued to assure the safety of persons at this operation and prohibits any work in the affected area until MSHA determines that it is safe to resume normal operations as determined be an authorized representative of the Secretary of Labor. The mine operator shall obtain approval from an authorized representative for all actions to recover and/or restore operations in the affected area.
This order was terminated on March 23, 2001. The
conditions that contributed to the accident no longer exist and normal mining
operations can resume.
Citation No. 7817895 was issued on March 28, 2001, under the provisions
of Section 104(a) of the Mine Act for violation of 30 CFR 56.4100(a):
A fatal accident occurred at this operation on March 20, 2001, when an explosion occurred as a result of an open flame being used where flammable gasses had accumulated. The victim had inserted a heater, consisting of a propane tank and a lit torch, under a truck scale to melt ice. The worker then covered the scale with tarpaulin to confine the heat. The flame from the torch consumed the oxygen levels in the enclosed space, eventually extinguishing itself. The propane, however, continued to flow and accumulate. The worker meanwhile left the area and later returned with a larger propane tank and a second torch. When the victim lit the second torch and introduced it to the accumulated propane down in the scale pit, the explosion occurred, resulting in fatal injuries to the victim.
This citation was terminated on April 4, 2001.
The operator has implemented a safe method of thawing scales in the future, will
follow appropriate confined space entry procedures including air monitoring to
ensure a safe atmosphere, and will train employees who will be assigned to the
task.
. Related Fatal Alert Bulletin: FAB00M05
Persons Participating in the Investigation
Michels Pipeline Construction, Inc.
Brian P. Johnson .............. executive vice
president and secretary
A. David Stegeman .............. general counsel, Michels
Ralph Miller .............. safety director
John Westerman .............. superintendent of all crushing
Joseph Schmitt .............. foreman, plant 4
Keith Martin .............. trencher operator
Richard Burrow .............. yard maintenance man
Fond du Lac County Sheriff's Department
Charles Sosinski .............. detective
Fond du Lac County Medical Examiner's Office
David Gustavus .............. chief investigator
Mine Safety and Health Administration
Ralph D. Christensen .............. supervisory
mine safety and health inspector
Stephen W. Field .............. mine safety and health inspector
Derrick M. Tjernlund .............. fire protection engineer
Michael Hockenberry .............. fire protection engineer
John S. Miller .............. mine safety and health specialist
Persons Interviewed
Michels Pipeline Construction, Inc.
John Westerman .............. superintendent of
all crushing
Joseph Schmitt .............. foreman, plant 4
Keith Martin .............. trencher operator
Fond du Lac County Sheriff's Department
Charles Sosinski .............. detective
Fond du Lac County Medical Examiner's Office
David Gustavus .............. chief examiner