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UNITED STATES
DEPARTMENT OF LABOR
MINE SAFETY AND HEALTH ADMINISTRATION

District 11

Accident Investigation Report
(Preparation Plant)

Fatal Haulage Accident
(Structural Failure)

Kellerman Prep Plant, I. D. No. 01-00563
Drummond Company, Incorporated
Kellerman, Tuscaloosa County, Alabama

November 28, 1995

By

Walter W. Deason
Coal Mine Inspector

Stanley J. Michalek
Civil Engineer
Pittsburgh Health Technology Center

Terence M. Taylor
Civil Engineer
Pittsburgh Health Technology Center

Originating Office - Mine Safety and Health Administration
135 Gemini Circle, Suite 213, Birmingham, Alabama 35209-5842
Michael J. Lawless, District Manager

General Information

The Kellerman Preparation Plant, Drummond Company, Incorporated, is located in Kellerman, Tuscaloosa County, Alabama on the Warrior River. The plant employs 57 miners and processes daily an average of 4,864 tons of clean coal. The plant operates two production shifts and a maintenance shift five to six days per week.

The plant has a barge loading facility that operates two to three shifts per day, five to seven days per week. The barge loading facility, on the day shift, loads clean coal trucked from the No. 4 Mine, Jim Walter Resources, Incorporated, located in Brookwood, Tuscaloosa County, Alabama. On the evening and owl shifts, the barge loading facility is used to load coal washed at the prep plant hauled in from the Kellerman-Peterson Mine, Drummond Company, Incorporated, located in Brookwood, Tuscaloosa County, Alabama.

The prep plant has three belts that transfer the coal after it has been washed. The No. 15 conveyor is the first clean coal belt out of the washer. The No. 15 conveyor transfers coal to the No. 16 conveyor. If the No. 16 conveyor is out of service, coal can be discharged at the end of the No. 15 conveyor onto the ground. The No. 16 conveyor transfers coal to the No. 17 conveyor.

The No. 17 conveyor belt is located approximately 100 feet above ground level and is 725 feet in length. The No. 17 conveyor belt is supported by four towers. They are located 200 feet apart. The towers are numbered one through four with the number one tower being nearest the river. There are four stalls located in the No. 17 conveyor belt. The stalls are located 200 feet apart. The stalls are numbered one through four with the number one stall being nearest the river. The stall sections are discharge locations where the different grades of coal are discharged and stored on the ground. The No. 17 belt was constructed in 1972. The prep plant had received notice that the plant was closing and was within two weeks of the closing date. The last Mine Safety and Health Administration (MSHA) regular health and safety inspection was conducted September 18-21, 1995.

Officials of Drummond Company, Incorporated are:

Garry N. Drummond................................Chief Executive Officer/Chief Operating Officer
Donald Baxter..........................................President of Mining
Ronald Handley........................................Director of Safety


Description of Accident

On Tuesday, November 28, 1995, at 4:00 p.m., the evening shift prep plant crew met in the eating area located on the first floor of the washer. Jimmy Ray, Outside Plant Foreman and Novey H. Dreher, Inside Plant Foreman, gave job assignments to the sixteen crew members.

The plant was idle due to the refuse slurry line being clogged. They assigned most of the plant crew to work on the slurry line and the remainder of the crew was to operate the belt to run bypass coal through the plant.

Gerald S. Noles, Inside Plant Foreman and Ruel Narramore, Outside Plant Foreman, came on duty of 6:00 p.m. They were informed by Ray and Dreher of the problems with the slurry line. At approximately 7:00 p.m., the crew that was working on the slurry line returned to the plant to eat lunch.

Harold Nelson Hubbard, Central Control Operator, called Noles and informed him that the No. 17 conveyor belt was slipping in the belt conveyor drive and had tripped out and that Jimmy Ray Ellenburg, Electrician, had reset the breaker and the overloads had tripped.

Noles and Gary Isabell, Table Man, went to the No. 17 conveyor belt to see if they could determine the source of the problem. As they examined the No. 17 conveyor belt, they noticed that the belt was loaded heavily. Isabell walked the No. 17 conveyor belt to the No. 1 stall and, while returning, noticed the cat walk leaning in the area of the No. 4 stall. Isabell brought this to Noles attention. Noles examined the area and returned to the first floor of the plant and informed Narramore.

Narramore and Isabell went to the No. 4 stall on the No. 17 conveyor belt to examine the area. Noles called Gene Narramore, Assistant Mine Superintendent, to inform him that the No. 17 conveyor belt was down and that there was a bent angle at the No. 4 stall that probably had the belt in a bind. Noles asked Gene Narramore if he wanted him to pull the men off the pipeline to get the No. 17 conveyor belt running. Gene Narramore told Noles to leave it alone that they could run coal off the end of the No. 15 conveyor belt and he would look at it the next day. When Noles returned to the first floor of the plant, Ruel Narramore had returned from examining the area of the No. 4 stall on the No. 17 conveyor belt. Narramore told Noles that what they looked at was old damage that had already been repaired. Noles told Narramore what Gene Narramore had instructed them to do and Ruel Narramore did not reply. Ruel Narramore told Noles to get six shovels and they could remove some coal off the No. 17 conveyor belt and get it running.

At approximately 8:45 p.m., Ruel Narramore, Noles, Isabell, Jack Pittman, Filter Operator, Jerry Taylor, Mag Man and Richard Benny Lowe (victim), Dozer Operator, left the plant going to the No. 17 conveyor belt. When they arrived on the No. 17 conveyor belt, Lowe started removing coal from the belt at the tailpiece and was working toward the No. 4 stall area. The other five men went down the belt to the area of the No. 3 tower and started removing coal from the belt. They were approximately 75 to 100 feet from the No. 4 stall.

At approximately 9:30 p.m., the No. 4 stall collapsed, starting a toppling effect. When the No. 4 stall fell, it pulled and twisted the No. 4 tower. The No. 4 tower was supporting approximately 100 feet of the No. 17 conveyor belt and the No. 16 conveyor belt and conveyor belt drive.

Approximately 100 feet of the No. 17 conveyor belt fell straight down and the No. 16 conveyor belt fell across the No. 17 conveyor belt. Five of the miners were trapped on the remaining structure of the No. 17 conveyor belt. Three men climbed down the No. 3 tower and the other two men were removed by the use of a crane and work platform, approximately two hours later.

Isabell and Tommy Styron, Truck Operator, located Lowe approximately twenty minutes after the collapse of the structure on the catwalk of the No. 16 conveyor belt that had fallen. There were no vital signs detected. The rescue squad located in Brookwood, Alabama, arrived in approximately twenty-five minutes. Lowe was pronounced dead by the medical examiner at the scene.


Physical Factors Involved

  1. The entire stacker belt structure, including the No. 16 and No. 17 conveyor belts was designed and constructed in 1972. These belts were used to handle the washed coal product leaving the preparation plant facility. Cleaned coal from the plant was transported up the inclined No. 16 belt. At its upper end, the No. 16 belt would discharge the coal onto the elevated No. 17 belt. The No. 17 belt was the coal stacker belt. Both belts were 36 inches wide. Based on the quality and properties of the washed coal product, the coal would be dumped from one of four deposition locations along the stacker belt.

  2. The No. 17 stacker belt structure was 725 feet long and was elevated approximately 100 feet above the ground. The belt rested on a truss structure. The No. 17 belt was supported by four steel frame towers and spanned 190 feet between towers. The No. 16 belt was supported at its upper end by the No. 4 tower. This tower was common to the Nos. 16 and 17 belt lines. The four columns common to the No. 16 belt truss were approximately 18 feet taller than the two outer columns supporting the No. 17 belt truss. The top level of the tower supporting No. 16 belt consisted of four horizontal beams tying the columns together. Once material was dropped onto the No. 17 belt, it could be deposited off three chutes, located midspan of the trusses between the four towers. The end of the trusses cantilevered out beyond the No. 1 tower. The No. 17 belt could also discharge off this final location at the end roller. The chute described as the No. 4 chute was located between towers 3 and 4. Similarly, the No. 3 chute was located between towers 2 and 3, and the No. 2 chute was between towers 1 and 2.

  3. The No. 17 belt truss consisted of three 5 feet deep, 50 feet long sections called suspended galleries. They were suspended from 50 feet long tapered trusses that extended from each of the towers. These are referred to as the intermediate galleries. The intermediate galleries were 15 feet deep at the tower locations and tapered to 5 feet deep, where they were bolted to the suspended galleries. Near the tower location the intermediate galleries were connected to the corbel galleries. The corbel galleries were 50 feet long and approximately 15 feet deep trusses. They straddled over each of the four towers. Each of the three chutes were located midspan of the suspended galleries. The suspended galleries consisted of single angle sections, while other galleries were composed of channels as well as angle sections. Most connections were welded.

  4. Two days prior to the failure under the No. 4 chute, it is believed a fracture occurred under the No. 3 chute. The failure occurred at approximately 5:00 p.m. on Sunday, November 26, 1995. The two bottom truss chords under the chute fractured at midspan. Both members were corroded from the constant exposure to moisture and built-up coal, and had experienced a loss of cross- sectional area. According to plant personnel, the bottom chords separated approximately 5 inches. The fracture occurred when the tension in the bottom chord exceeded the capacity of the angle section. Five sections over from the No. 3 chute, the bottom chord buckled when the compression load in the angle section exceeded the critical buckling load of the member. The buckle of this bottom chord member most likely occurred immediately prior to the bottom chord separation under the No. 3 chute.

  5. The No. 3 chute is located near the geometrical center of the entire No. 17 belt structure. It is centrally located between the No. 2 and No. 3 towers. Both of these towers are symmetrically loaded by the belt truss frame. When the bottom chord under the No. 3 chute broke, the entire truss did not fall to the ground. The top chord remained intact. The suspended truss structure under the No. 3 chute was held in place by the cantilevered support being provided by the tapered intermediate truss sections, extending from both the No. 2 and No. 3 towers. Both of the cantilevered trusses remained stable, because they were symmetrically balanced over their respective towers.

  6. The truss size and shape under chute No. 4 were identical to that under chute No. 3 with two angles 3" x 3" x 3/8" used for the top chord and two angles of identical size composing the bottom chord. These truss members were also severely corroded, as there was coal built-up on the bottom chords of the truss. Measurements taken of the fractured truss members under chute No. 4 were as follows:
                                                 MEASURED         MEASURED        REDUCT.
                     ORIGINAL     ORIGINAL      THICKNESS*       LEG LENGTH         IN
                    LENGTH OF    THICKNESS         (in)             (in)          CROSS-
                      EACH        OF EACH     --------------   ---------------    SECTION
                       LEG          LEG       VERT.   HORIZ.   VERT.    HORIZ.     AREA
 CHORD     SIDE       (in)         (in)        LEG     LEG      LEG      LEG       (%)

  Top      Woods       3           .375      .271     .250    3.000     3.000       29

  Top      Plant       3           .375      .325     .257    2.500     2.627       33

 Bottom    Woods       3           .375      .179     .174    2.500     2.375       61

 Bottom    Plant       3           .375      .115     .162    2.313     2.375       70

* thicknesses were measured approximately 1.5" in from the fracture

The two bottom chord members under chute No. 4 experienced a reduction of up to 70% in cross-sectional area. Due to the potential instability of the remaining portion of the No. 17 belt truss still standing after the collapse, the investigating team was unable to take caliper measurements of the chord thickness under chute No. 3. Therefore, a dimensional comparison could not be made.
  1. Chute No. 4 was located between towers 3 and 4. Tower No. 3 was an interior tower, whereas tower No. 4 was an exterior tower (meaning it is located at the end of the No. 17 belt superstructure). In general the interior towers were loaded symmetrically by the truss, while the loading on the exterior towers was unsymmetrical. In comparison, chute No. 3 was located between towers 2 and 3, both of which were symmetrically loaded towers. It is believed that the reason the structure did not collapse when the chord under the No. 3 chute fractured was because the superstructure was still symmetrically balanced over Towers 2 and 3, which minimized any overturning effects of these towers.

  2. Perhaps the reason the fracture occurred at chute No. 3 two days earlier was due to a more advanced stage of corrosive deterioration under chute No. 3, although no measurements could be taken. Eyewitness reports from workers who repaired the break indicated the bottom chord members of the truss were severely deteriorated.

  3. In conducting the failure investigation, there was evidence indicating that the belt was fully loaded beyond chute No. 2. There was also eyewitness testimony that the belt was overloaded. At the time of failure, men were on the structure shoveling off excess coal to restart the No. 17 belt that had stopped possibly from an overload. There was also a considerable amount of coal heaped around the No. 3 chute.

  4. There were other signs of prior structural distress as well. At the location of the No. 4 chute, the top chord had previously buckled approximately three feet over from the section that failed. This suggests that, in the past, the capacity of the top chord member had been exceeded, probably due to a loss of cross- sectional area from corrosion. None of the individuals interviewed were knowledgeable of when this prior buckle had occurred. In the suspended gallery section of truss, the bending moments were largest under the No. 4 chute. Therefore, the angle section top chord was experiencing its highest compressive load at this location and it followed that this area would be the first area to experience a compressive buckle. The company had repaired the buckled top chords by adding a new angle section and bolting it to the bent member.

  5. Reportedly, some "dirty" coal had been run through the plant in the weeks prior to the collapse. This coal had a considerable fraction of fine-grained, cohesive particles combined with the coal. During the investigation, it was observed that material with this characteristic had accumulated unevenly on one of the rollers under the No. 4 chute. This build-up of material would have caused the belt to track unevenly and could have accelerated the fracture by causing additional dynamic forces. In addition, in the hours leading up to the collapse, witnesses had reported that it had been raining. The belt canopy was missing over many areas of the belt. The wet conditions would have added weight to material on the No. 17 belt. All the above factors could have caused the belt to slip on its drive rollers, which would have slowed it down, allowing the belt to accept coal from Belt No. 16 at a faster rate than it could transport it.

  6. The culvert beneath the No. 4 tower was inspected for collapse and was found to be in its original shape. In addition, the base elevations of the six columns were surveyed to check for differential settlement. The column pedestals were acceptably level and, therefore, a foundation settlement failure was eliminated as a possible cause of the collapse.

  7. It is possible that the connection of the No. 17 belt truss to the top of the No. 4 tower may have failed prior to the fracture of the truss at midspan beneath chute No. 4. Under this scenario, overload of the No. 17 belt may have over-stressed the connection of either the front or rear legs of the No. 17 belt support. The front connection could have either sheared downward or the back leg lifted upward. If either connection failed, the truss between towers No. 3 and No. 4 would dip downward over-stressing and fracturing the bottom chords, then top chords, before ultimately rotating to the ground. The connections at this location were partially corroded, however no measurements were taken. If the structure failed in this manner, the truss could still have fallen through the No. 4 tower causing impact damage to the cross members and destabilizing the common columns with the No. 16 belt. As with the previous failure scenario, the events following a destabilization of the No. 16 belt would be similar. In addition, this type of failure could also have been the result of steel corrosion and belt overload.

  8. Based on the structural analysis, it appears that four events occurred to ultimately collapse the structure:

    1. The top chord near midspan had to first buckle, as it experienced the highest compressive loads. As mentioned earlier, this chord under chute No. 4 had, in fact, buckled previously.

    2. Once the top chord buckled, the load redistributed, over-stressing the bottom chord of the suspended gallery section near its end location, where the truss connects to the intermediate gallery section. This chord would then buckle from the load increase.There was evidence under chute No. 3 that its end chord buckled near the interface of the two truss sections. The similar section of truss under chute No. 4 had been damaged by the failure, and it was not possible to verify whether an identical buckle had occurred in this location, although it seems likely. Its observed condition was buckled, however, there was the possibility that the chord bent after the main truss was rotating downward. Based on the previous experience of the condition of the suspended gallery under chute No. 3, it seems reasonable to expect a similar buckling behavior in the suspended gallery supporting chute No. 4.

    3. With both the top chord under the chute and the bottom chord at the end of the suspended gallery buckled, the tension loads in the bottom chord directly beneath the chute increased significantly. The results of the analysis indicate that the tensile force at the time of failure, in combination with the reduced cross sectional area measured during the investigation, produced a stress in the bottom chord near its yield level. This yielding member elongated or "necked" to the point where its cross-sectional area further reduced. The reduced area in combination with the member tensile force, caused the member to fracture. Field measurements along the feathered edge of this member further substantiated that the stress in the member along its fractured edge was at its predicted fracture strength.

    4. After the bottom chord fractured, the entire load transferred to the support connections at the top of tower No. 4. The connections became over-stressed and failed, then the truss began to fall. The rotation downward then failed the top two chords at midspan. This final fracture occurred when there was considerable sag at midspan of the suspended gallery. The skewed frame showed that the top chords were being pulled upward when they failed. Based on the direction of the skew, it appeared that the plant side chord was the last to break.


Conclusion

The failure of the No. 17 stacker belt was most likely the result of a sequence of buckling and fracture of truss chords within the suspended gallery section, which supported chute No. 4. The evidence indicates that the belt was fully loaded and the load carrying capacity of the No. 17 truss had clearly been reduced by the amount of corrosion on the structural steel members. A load redistribution from these events led to a failure of the connection at the top of tower No. 4, allowing the belt to fall through the tower and destabilize the No. 16 beltline. Ultimately, these deteriorated conditions of the structure caused it to collapse, resulting in the fatality of an employee.


Violations

  1. A 103-K Order No. 3397389 was issued to ensure the safety of miners until the investigation was completed.

  2. A 104-A Citation No. 3021236 was issued for a violation of 30 CFR Section 77.200. The No. 16 and No. 17 conveyor belt lines and support structures were not being maintained in good repair, so as to prevent accidents to employees.

  3. A 104-A Citation No. 3021237 was issued for a violation of 30 CFR Section 77.1713. Daily inspections were not being performed during each working shift on all active working areas.



Respectfully submitted by:

Walter W. Deason
Coal Mine Inspector

Stanley J. Michalek
Civil Engineer

Terence M. Taylor
Civil Engineer


Approved by:

Michael J. Lawless
District Manager

Related Fatal Alert Bulletin:
Fatal Alert Bulletin Icon FAB95C41