INDUSTRIAL ENGULFMENT RESCUE CONSIDERATIONS BY ROBERT RHEA

INDUSTRIAL ENGULFMENT RESCUE CONSIDERATIONS BY ROBERT RHEA

The information presented here will assist rescue teams in evaluating the hazards present and in developing tactics and methods for performing rescue operations at surface mining facilities, industrial complexes, and other potential engulfment accident sites. A variety of potential rescue scenarios exist at these facilities. Because you can find such facilities in most response areas or surrounding mutual-aid jurisdictions, you will need additional information and training on this subject.

This article is based on case studies of past incidents; safety and training information supplied by the Mine Safety and Health Administration, NIOSH, and related OSHA standards; and actual visits to these facilities and interviews with plant personnel.

SURFACE MINING FACILITIES: BINS

AND HOPPERS

Surface mining facilities include plants that operate actual stone quarries that perform rock-removal/blasting operations on-site and prepare the product for sale as well as those facilities that store the mined product and facilitate the sale and transfer of the product to the customer. However, the information contained here applies to any type of facility that may contain similar facilities, equipment, and engulfment hazards.

The major/structures facilities that can be found on-site include the following: bins and hoppers, draw off/feed tunnels, elevated walkways and conveyor systems, crushers, storage piles, and surge piles.

BIN/HOPPER HAZARDS

Bins and hoppers present the following hazards:

Elevated structures present will dictate the potential for falls and the need for high-angle rescue operations.

Bins and hoppers have been associated with approximately 42 deaths in industry between 1980 and 1988, according to the Mine Safety and Health Administration.

The primary reason for death has been suffocation.

The bridging-over or clogging of a draw point may require that workers enter an area not normally used for continued employee occupancy. While trying to unclog the bridged-over material from above or below, the workers can become trapped should the material suddenly break loose.

Any bin, hopper, silo, surge, or storage pile of granular material may look completely deceptive. The center of the material has the potential to give away at any second. Free-flowing material such as sand, coal, or limestone will at any moment increase its flow and move rapidly.

Personnel working in partially filled, closed storage bins may become covered by materials that fall from banked walls inside the bin (material clinging to the bin`s sides).

Any operating machinery inside a bin or hopper could pose dangers.

The material contained should be considered unstable. Do not walk on top of material inside a bin or hopper without being supported independently by a lifeline.

Bins, silos, and hoppers may be equipped with mechanical diggers, vibratory motors, or other mechanical means to keep material from clogging. These devices will be a hazard to rescue personnel.

Bins/silos over 20 feet in diameter are potentially a more severe hazard than smaller bins for the following reasons:

–Large masses of material are involved.

–Any material shifts are more dangerous.

–Flow accessories are not as effective.

–Unscreened crushed rock or ore routinely presents a greater flow problem than bins with finished product.

–The bins generally have only one vertical opening; workers cannot easily reach the necessary work area to clean walls or induce flow and often are lowered onto the material surface to work.

–The preferred installation will have a suspended and adjustable platform that can be lowered in place to allow work from above the trouble spot.

DESIGN/MATERIAL FLOWABILITY

CONSIDERATIONS

The design of bins/hoppers and the installation of proper flow-aid accessories should be based on the flowability of the materials. There are four categories of materials.

Very free flowing. Materials will flow through almost any size opening with no help. Examples are grains and plastics.

Free flowing. They flow about as well as the previous category but may occasionally need a flow aid.

Average flowing. They require a constant flow aid, such as a flow of air or a vibratory motor. The majority of materials fall in this category.

Sluggish. Materials in this category should have a bin designed specifically for the product.

Generally, a material`s classification is based on it size, shape, hardness, and moisture content. As a general rule, extremely fine powders such as talc or dusts will quickly pack and dry. Uniformly sized larger materials will be free flowing.

Weather conditions may change the flowability of the given material. Added moisture from rain or freezing conditions may change the classification of the material.

DRAW OFF/FEED TUNNEL HAZARDS

The following hazards are associated with draw off/feed tunnels:

Entrapment of workers trying to clear bridged-over material from above or below.

Moving conveyor belts and operating machinery.

Flowing product during normal operation.

Extreme noise levels.

Extreme dust accumulations.

Prolonged exposure to full-body vibrations from vibratory flow aids.

Confined space hazards.

When working in these tunnels, lock-out procedures are a must, and the tunnels should be equipped with emergency shutdown switches and escape tunnels.

STORAGE PILE/SURGE PILE HAZARDS

The following hazards are associated with storage piles/surge piles (material piles that are pushed into a tunnel feed opening):

Some materials will have a cementing or coagulating texture, which could result in a banked wall effect.

Material-removal operations could result in an undercut wall with dangerous overhang.

Workers in an unsafe area may be pushed or fall into a feed opening. Workers standing on top of a surge pile may be drawn into a tunnel feed opening.

Pockets from bridged-over materials may exist in storage piles.

RESCUE OPERATIONS/SAFETY PROCEDURES

Use the following safety procedures in rescue operations involving these facilities:

1. Confer with the plant personnel to ascertain the following:

The exact details of the situation, location of incident, and best access route.

Hazards.

Machinery and types of materials involved.

Machinery shut-offs and lock-out procedures.

2. Operations specific to storage and surge piles include the following:

Perform a good assessment.

Limit the number of people exposed to the surge/storage pile area.

Use ground pads to distribute weight when gaining access to the patient and while operating on the pile.

Use portable ladders, an aerial ladder, or a crane with a work platform for access when appropriate.

Use safety lines on each rescuer; maintain minimum slack on these lines while rescuers are on the pile.

Use an aerial ladder, cranes, or surrounding structures for overhead anchors for safety lines, if possible.

Prior to digging to free the victim, attach a safety line to the victim.

Prior to digging, if possible, use a barrel or pipe as an isolation tube around the victim to limit additional material from engulfing him.

3. Operations specific to bins/hoppers and feed tunnels include the following:

Before personnel enter, isolate and lock out machinery and flow of material.

When entering bins/hoppers, limit exposures to areas below banked wall materials.

Entry into bins and hoppers exposes rescue workers to the danger of engulfment. Void spaces under bridged-over material may suddenly and at any time collapse and engulf the rescuer. This hazard dictates the need for independent suspension of the rescuer using rope systems.

Rescuers will experience difficulty working upside down suspended from rope systems. Staffing requirements will increase. Work times must be shortened.

Consider the potential for confined space hazards at these structures.

Magnetic pickup devices may be used at the plant. They will be located along conveyor systems to remove foreign metal objects from the material product. Be aware of the possible existence of these devices, and use caution when working around them. They can pull a tool out of your hand or pull you into the conveyor system.

The potential for the collapse of feed tunnels or becoming entrapped in them by large quantities of flowing materials dictates that you always consider these structures to be confined spaces when effecting a rescue. Use confined space operational procedures, and remember to check for the existence of an escape tunnel as a primary or secondary means of entry/egress.

STRATEGIC AND TACTICAL CONSIDERATIONS

1. Consider placing a protective barrier around the victim to limit additional material from sliding in and further burying him. This barrier can be constructed on-site using substantial lumber, lightweight trench boxes, or prefabricated shoring panels. Various corrugated piping or drums are also a valid isolation device. If the opening to an enclosed bin is too small to allow the entry of protective barriers, enlarge the entrance using a power tool, if necessary.

2. You may need aerial devices such as aerial ladders, tower ladders, cranes, or elevated work platforms for placing rescuers, tools, equipment, or protective barriers. Or you may need them as an overhead anchor for rope systems.

3. Using mechanical flow-control devices to lower the level of the engulfing material may be a valid tactic if you can maintain good control during their use.

4. Preplan specialized equipment such as air-powered digging equipment and air-powered material vacuums. You can use large industrial vacuum trucks to remove engulfing materials from sewers. Rescue teams should identify the locations of this equipment and train with the crews who operate them.

5. Maintain an outside standby rescue team at all times.

6. Consider all stored material to be bridged-over with the potential to collapse.

7. Plan for the use of hand-digging equipment such as entrenching shovels and vacuum excavators or air pick devices.

8. Staffing needs will increase due to rotation needs of rescuers, standby teams, and support operations. Plan for this early, and call for additional resources.

9. Construction features of the storage bin/hopper may allow a work platform to be placed just above the material. It can be constructed with lumber cut to size and supported by the internal ribbing of the storage bin or the hopper`s walls.

10. Shut down all sources of vibration near the engulfment area to limit the potential for movement of the material.

11. Secure personnel transported in and out of an open top hopper or surge/storage pile area by crane and work platform with appropriate fall-protection equipment.

12. You must acquire and appropriately measure lumber for shoring moving product. You will need cutting tools to implement shoring operations around the victim.

13. Communications between the incident commander, rescuers, and support operations are extremely important. Backup batteries for portable radios will be needed for long-term operations.

14. For long-term operations in wet or cold weather conditions, you will require equipment for heating the rescue site to limit the effects of hypothermia on the victims. Rescuers will require more frequent rehabilitation.

15. Emergency medical care for the victim will include treatment for respiratory distress from the effects of the material`s constricting movement of the chest or the effects of total burial. Crush syndrome and hypothermia will also be concerns. Depending on the material of entrapment, the victim may benefit from placing the appropriate respiratory protection device to assist survival. Advanced life support measures should be initiated after the area has been made safe by removing material overhead, placing a protective barrier, and using independent support lines. Spinal immobilization devices that can be positioned around the victim while still trapped will be needed.

16. Implement rope operations and techniques that will ensure that rescuers are supported above the engulfing product. Full-body harnesses are necessary for this type of rescue. Boatswain chairs will allow rescuers to perform some work close to the patient while limiting the rescuers` body weight on the flowing product. n


Material storage piles and surge piles appear harmless, but they are potential engulfment problem areas. (Photos courtesy of author.)


You will need air vacuums or small digging tools for material removal. Rescuers must remain attached to rope systems during the rescue.



(Left) Isolating the victim from the engulfing material will protect him and assist in his extrication. (Right) Aerial ladders and cranes can be used to place isolation devices.

ROBERT RHEA is an 18-year veteran of the Fairfax County (VA) Fire and Rescue Department and currently is assigned as a battalion chief in the Emergency Services Division. He is rescue team manager of the Fairfax VA-TFI, USAR Task Force. He has served as the senior technical officer in charge of the department`s Technical Rescue Operations Team.

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