A deep breath
Published: 04 July, 2011
Carrying out a rescue in the most dangerous confined space entry in the world presents one set of problems – but two sets of safety rules makes it even more complicated, writes Neil T Lipski of the National Tunnel Institute.
The economies of many countries today are based in whole or in part on mining. Due to the huge impact a mining loss would have on a country’s economy, loss prevention in the mining industry is administered via rules, regulations and safe practices.
The health and welfare of the public relies on tunnels both for the safe transfer of sewage to treatment plants, the effluent outflow tunnels from treatment plants, as well as subway, train, fresh water, and vehicle and pedestrian movement tunnels. It should be noted that despite these rules, regulations, and safe practices, deaths and injuries continue to occur. It is during these occurrences that rescue teams play a huge role in mitigating these mine and tunnel emergencies.
The focus of this article is to discuss the rescue function and the rescue equipment used. Today, mining and tunnelling incidents represent potentially the most dangerous confined space entry in the world. The basis for this article will be rescues that have occurred in the mine and tunnel industries based in the United States and Puerto Rico.
Mining in other countries is quite similar in many respects, however some differences do exist. Contemporary multi-tiered mines with numerous working faces as well as tunnels with their great lengths and in many cases having only a single entry and access point present unmatched problems for rescuers. In the United States, the Mine Safety and Health Administration (MSHA) controls the mining industry, whereas the Occupational Safety and Health Administration (OSHA) controls the tunnelling industry.
The difference between the two lies in the finished product. In the mining industry the product is what is removed from the ground (coal, salt, gypsum, etc.). In the tunnelling industry the product is the hole left in the ground, with the material removed as waste. Having two sets of governing bodies creates a guidance problem because of the following: MSHA controls the mining industry and is very specific concerning rescueequipment needs and guidelines. Conversely, OSHA is weak concerning rescue equipment and guidelines. It is because of this disparity that the information contained in the MSHA manual, the Code of Federal Regulations 30 (CFR 30), should be used instead of OSHA’s CFR 29, which governs tunnels – and in practice this is already occurring.
Many tunnel owners are requiring that MSHA guidelines be followed as it concerns rescue even though OSHA is the governing body. This is safer and more pragmatic as it sets a higher standard of needs and equipment for the rescue team. To enhance the safety of the rescuer (as well as the rescuee) an MSHA driven statement of rescue needs, equipment, and standards should be included in every tunnel contract. A focus on rescue equipment is critical to this process.If the aforementioned is perceived as bothersome, realize that that is only the first issue in a series of issues that should cause us concern.
Another tunnel and mine rescue concern is the physical limitations of modern rescue equipment. The breathing apparatus used in the United States and abroad is the four-hour, closed circuit, oxygen-rebreathing type. When tested and used properly, the units provide and are approved for a full four hours of wear time. A critical distinction must be drawn when evaluating the true length of time available for entry. Only 40% of a four-hour rebreather should be used for entry (in effect reserving sixty percent for egress). This alone indicates that from the standpoint of entry we are limited to less than two hours. Given a casual review of the mining industry, with its many tiers, room and pillar construction, and miles of haulage ways, it becomes very apparent that these units are inadequate based on the potential distances required. This causes the rescue team to use a leapfrogging techniques or fresh air bases in order to finally get into the actual rescue position.
While it is true that many rescue teams have effected rescues in these types of mines, it should also be noted that it is just as true that our rescue breathing apparatus and our capability to rescue at great distances and depths has not kept pace with the need. One needs only to understand that the engineering that goes into mining and tunneling greater distances (and the productivity demands placed on work crews) far exceeds the engineering put into establishing better rescue equipment. Much of the equipment available today has long been the status quo, with no alternatives offered.
The exact physics and chemical reactions used in the four hour oxygen-rebreather units decades ago is used in the modern, dressed up units of today. This is not an article that provides a solution for the lack of equipment that would give us much greater duration. Rather, it emphasizes and re-emphasizes that the rescue equipment in its present state has not kept pace with the distances and depths of our mines.Consider an actual rescue scenario.
During a rescue with good vision and upright travel a rescue team is capable of striking, in the less than two hours afforded for entry, a very small portion of the distance required. Thus, the breathing apparatus has been the primary determining factor in rescue team reach, not, most definitely, the actual working distances being achieved in contemporary mines and tunnels.
Rescue team members are capable of performing rescues under the present equipment limitations. The people involved in rescue are selected based on their ability to perform. The breathing apparatuses are selected based on their maximum usage or duration. The limiting factors for a rescue are severe and having only a four-hour apparatus available is both a godsend and a hindrance. It is a godsend because four hours is greater than three, and the extra time may be the difference between life and death. It is a hindrance because four hours is likely not enough time.
The specifications concerning the four-hour oxygen rebreathers revolves solely around the rescue team members and carries no information for those that we are trying to rescue, other than the self rescuers that are required to be in the mine or tunnel. On a rescue team’s best day, they are limited by the duration of modern breathing apparatus. Surprisingly, there are alternatives. OSHA limits supplied air systems to three hundred feet in length. That limitation appears to this author to be in part responsible for the problem.
Whether in mining or tunneling a supplied airline under pressure is a solution that is long overdue. An airline plug-in on the compressed air line every fifty feet (or at a more effective or efficient interval as determined by studies) is a much safer alternative for everyone concerned. This would allow the miner or tunneler to carry a lightweight facemask and hose in a sealed bag that when needed could be donned and used every 50 feet while exiting. It is this author’s opinion that the authorities having jurisdiction for the approval of such a system have lobbied to prevent an inline compressed air system (ILCAS) from becoming reality. If this is not true, than the ILCAS needs to be given its due respect. Very obviously an ILCAS air source would be a huge advantage to someone trying to exit a mine or tunnel.
It is this area that we need to focus on. Tunnels are not typically built with multiple levels (or tiers) but in many cases have only one entry and exit point, the shaft. Horizontal distances in excess of seven miles long are not unheard of. This has the very real potential of preventing the rescue team from getting within striking distance of the objective for rescue.
The lack of tiers, in this case, further hinders progress as it eliminates the option of bypassing a problem area via a different level. While fans are reversible, directional ventilation used in tunnels means that a fresh air base concept is questionable at best if you are entering with air in your face. The guarantee of the fresh air base behind you is suspect at best if the tunnel is on positive pressure ventilation. It means that the contaminants are being forced towards the rescue team as they are entering. This in fact eliminates the ability to ensure fresh air behind the entering rescue team. Having worked in this industry and participated in numerous tunnel rescues since 1982, my recommendation is the following: all headings, haulage ways and working areas should be supplied with breathable, filtered, compressed air piping.
Realize that compressed air lines work well over great distances. Air used in this system would need to be filtered to ensure that is free of oil, contaminants, and other particulate matter. The compressed air piping system also would protect the rescuers in the event of mask failure as they still would have a means of self-rescue attached to their belt, acting in this case as a secondary, or redundant means of self-rescue.
Equal weight needs to be given to tunnelers and miners when exiting as is given to the rescuers entering. If the concern is truly to rescue the trapped victims, the OSHA limitation of 300 feet and other self-rescue equipment available for use by those that would be trapped demands more attention. The inline compressed air rescue system concept is long overdue and should no longer be lobbied out of the application process. It does not eliminate the need for four-hour oxygen rebreathers; the inline rescue system requires the trapped or escaping member to be conscious and interacting with the system.
Those who are incapacitated would still require rescue. There is a fundamental need to evaluate the present engineering of today’s rescue equipment. There is much to be gained by enhancing both the entrapped victims’ and the rescuers’ respiratory protection. Every step a miner or tunneler takes towards the exit is worth four steps of the entering rescue team.