ENTRAPMENT IN GRAVEL HOPPER CHALLENGES RESCUERS
BY MICHAEL G. BROWN
On November 11, 1996, the Chesapeake (VA) Fire Department (CFD) was called to the report of a “man trapped” at LaFarge Calcium Aluminate Corp. in the 100 block of Ohio Street, in the South Norfolk area of Chesapeake, a large industrial complex bordering the Norfolk and Chesapeake city limits. On arrival, CFD`s Engine 1 was met by LaFarge employees, who stated a man was trapped in an elevated hopper (shaking machine) approximately 60 feet high, on the dock adjacent to the heavily traveled Elizabeth River. The hopper receives “Clinker 41,” a fabricated gravel composite delivered by a huge clam-shell bucket and crane on the dock. Clinker is removed from ocean-going colliers, deposited into the top of the hopper (approximately 50 feet by 50 feet by 40 feet deep, elevated to about 60 feet in the air), where it is shaken by hydraulic rams, not unlike a massive vibrating funnel. The gravel is then transported to various on-site storage facilities.
Initial size-up by Engine 1`s crew indicated that a worker had descended into the giant opening of the hopper in an attempt to unplug a clump of hardened gravel that was preventing several hundred tons of Clinker 41 (large chunks about the size of a balled fist) from shaking down into the separator. (Stomping onto and poking a metal rod into the gravel to free up blockages in the vibrating hopper is apparently not an uncommon occurrence.) The victim was trapped up to his thighs in the material and conscious but in considerable pain. The shaking mechanism had been turned off, and coworkers were attempting to dig the victim out of the product.
Battalion Chief Paul Brandt and Para-medic Bobby Pugh discussed immediate safety requirements and strategies. Their first move was to remove the coworkers from the hopper and secure an effective lockout and tagout of the machinery and electricity. Initial response teams comprised of Engine 1, Engine 82, and Ladder 2 were instructed to don the Class III harnesses kept on Ladder 2; attach them to rescue ropes for fall protection; and descend into the hopper to attempt to dig the victim out of the gravel. This safety precaution of maintaining independent rescuer support proved effective and warranted when on at least two occasions the Clinker shifted and large holes opened up, which had the potential to suck rescuers and equipment into entrapment. Rescuers were easily belayed to awaiting ladders on three sides of the hopper. The victim was secured with a Class III harness, which was fastened over his shoulders and tied off to the top of the hopper. His helmet was replaced on his head.
VARIOUS ATTEMPTS FAILED
Initial efforts to free the victim proved fruitless. In fact, he was sinking gradually, and his pain was increasing proportionately to the escalating weight of the gravel on his legs. Brandt and Pugh [both members of the Tidewater Regional Technical Rescue Team (TRTRT)1 and VA Task Force-2 (TF-2)] notified dispatch of the need for additional personnel, equipment, and expertise. A call was made for the on-duty members of the TRTRT.
The Virginia Beach TRT component arrived approximately 15 minutes later and conferred with Brandt and Pugh on the status of the ongoing rescue attempt. TRT members began arriving at staging and received detailed instructions from incident command and on-scene technical operations team managers. TRTRT rescue specialists replaced exhausted initial fire and rescue workers on ropes in the hopper.
Numerous attempts–isolation tunneling, limb confinement, gravel stabilization, innovative and modified digging tools, and so on–to dig the victim from the product only caused him to sink further and intensified his pain. Paramedics maintained IV lines, conferred with emergency room staff, maintained vitals checks, and administered pain medication. As the seemingly simple “dig-out” rescue approached the three-hour mark, a call for additional TRTRT members was dispatched throughout the Tidewater region.
To this point, the victim`s status remained stable. However, paramedics reported worsening pain and increased signs of shock. Due to the entrapment, the extent of injury to the legs was impossible to determine and Compartment Syndrome (compression of the trapped portion of the body impedes circulation and causes proteins to break down into toxins; when the victim is freed, the rush of toxins from the previously compressed portion of the body through the body can cause complications such as renal failure–similar to crush syndrome) was becoming a greater concern to the medics.
The technical operations team managers sent out a call for three additional resources: Dr. David Cash, one of VA TF-2`s trauma physicians, who had a reputation for climbing into the danger zone with the rescue specialists; Jim Torrey, one of VA TF-2`s heavy equipment riggers; and the “Supervac” vacuum truck from the Virginia Beach Public Utilities Division.
A four-step plan was devised to accelerate the victim`s removal from the hopper:
1. Get Dr. Cash down to the victim to perform a thorough examination and upgrade medications as required.
2. Use the giant Supervac hose (if it would reach from the dock) to suck the gravel away from the victim, facilitating his removal.
3. Make a “bosun`s chair” of sorts to support the victim from any further settling and to help in removal when he was freed.
4. Set up for heavy torch (burning) operations should nothing else work.
Firefighters and rescue workers from Chesapeake and Norfolk would continue digging out the Clinker by hand and tossing it safely into the river while preparations for the four-step plan were underway.
The doctor made medication adjustments and a final evaluation of the victim. Rotating crews of rescue specialists built a removal/lifting rope system and attached it to and fitted a modified bosun`s chair to the victim. The hose on the Supervac would not reach the top of the hopper; however, it was fully capable of removing the Clinker 41 in large quantities. A smaller, towed version of the Supervac could be lifted to the top of the hopper via crane, but it was not capable of sucking up the hand-sized gravel.
It was decided to attempt to cut the heavy steel underneath the victim to attempt to “drain” the gravel away. There was some concern that unusual shifting of the load in the machine would further complicate his injuries. Atmospheric monitoring and the relatively open area of the hopper ensured a safe environment for torch operations. Hoselines were stretched for spark suppression. All other operations were stopped, and the entry team was reduced to two rescuers on standing (on the gravel) rope belay. One rescuer was “floated” into position inches above the victim, attached to a “shutdown, locked, and chocked” crane boom by a rope system hooked to the rear “D” ring on a Class III harness. While not particularly comfortable, this effectively put a hands-free rescuer, out of harm`s way, immediately in the face of the victim.
Torrey and a group of rescue specialists began cutting an access hole waist high and about four feet away from the victim. This cut was a test of sorts, releasing some of the gravel and giving rescuers access to the victim through the wall. That cut seemed successful, and it was determined to continue with another, closer, and more aggressive cut under the victim. Torrey made a triangular cut in the 12-inch steel plate, causing some of the gravel to flow harmlessly into the river below. Some prodding of the gravel with a shovel handle made it unnecessary to open the cut further, which could possibly have induced rapid movement of the product.
From the top, the gravel seemed to magically fade in a conical swirl from around the victim. The two rescuers standing belayed on top of the gravel scrambled to the safety of their egress ladders. From the bottom, the thundering of tons of gravel could be heard throughout the industrial area. Suddenly the victim was floating in his modified bosun`s chair, securely hugged by his floating rescue specialist.
REMOVING THE VICTIM
The victim was moved horizontally and up onto a stabilized section of the gravel for placement into the stokes litter and medical evaluation.
A two-rope raise/lower system had been secured to the stabilized crane boom. A rescue specialist with a radio was sitting with the crane operator to ensure that the crane remained off and in the locked position. The victim was packaged for the raising operation out of the hopper. The raising operation consisted of two 12-inch low stretch kernmantle ropes reeved through a double sheave pulley anchored to the crane boom. The raise was accomplished by three rescue workers hauling on a 4:1 simple mechanical advantage pulley system, piggybacked onto the “main” line with tandem prusiks. Tandem 8-mm prusiks were attached to the main line and the belay line, to act as safety brakes. The load–victim, rescue specialist/paramedic, stokes basket, and medical equipment–was raised out of the hopper. Ground crews then tag lined the load over the edge of the hopper. A closed-end rack was added to the main line for descent control, and the load was lowered approximately 60 feet to the ground and an awaiting ambulance. Ultimately, the victim fully recovered from deep muscle bruises and minor circulation injuries to his legs. He returned to work one week later.
1. The Tidewater Regional Technical Rescue Team (TRTRT) was founded in 1987, answering the growing Hampton Road area`s requirements for specialized rescue services. Hosted by the Virginia Beach Fire Department, neighboring cities of Norfolk, Chesapeake, Newport News, and Franklin and personnel from the Norfolk Naval Operations Base, Little Creek Amphibious Base, and Dam Neck Naval Base provide 24-hour-a-day technical rescue services to the approximately two million inhabitants of the Tidewater, Virginia, area. The regional concept has proven to be a highly successful example of how interjurisdictional cooperation can be combined to effectively handle low incidence/extremely high-hazard rescue calls. The team is also home to FEMA`s Virginia Task Force 2 (VA TF-2).
MICHAEL G. BROWN is a fire captain with the City of Virginia Beach (VA) Fire Department, currently assigned to the Division of Fire Training. He has an extensive background in technical rescue team development, regionalization concepts, and high-performance special operations team integrity training. He is captain of Virginia`s Department of Fire Programs, Heavy and Tactical Rescue Team and of the Tidewater Regional Technical Rescue Team. He is heavily involved with FEMA`s Urban Search and Rescue program as rescue team manager of VA Task Force-2. Additionally, he is a FEMA rescue specialist instructor and FasT (Field Assessment Team) member. He is a partner with Spec. Rescue International, a technical rescue training and consultation company, and a Fire Engineering editorial advisory board member.