THE CURRENT STATUS OF LAWS AND REGULATIONS REGARDING HYPERBARICS

摘要

Working under compressed air for tunnel excavation has traditionally been applicationswhere the entire tunnel was pressurized and the workers remained under pressure forthe entire shift. These tunnel excavations were usually at pressures below 20 psi butthere were some applications at greater pressures, with 50 psi being the maximumpressure allowed. The majority of the current regulations for Compressed Air Workersin the tunneling industry were generated for this type of compressed air excavationof the tunnel and do not reflect recent advances in technology and equipment. Withadvances in compressed air technology and improvements in tunnel equipment andmethods, tunnels are now capable of being driven in geologic conditions that werenot possible before these advances. The regulations that govern working conditions inthose circumstances have not kept up with the advances and this paper will detail thecurrent status of efforts to revise those regulations.Tunnel boring machines have revolutionized the tunneling industry in recent years.While the techniques have evolved a great deal, the regulations in the United Stateshave not kept pace. The regulations were written for a time when a section of the tunnelwas isolated with a pressure bulkhead and the tunnel itself was pressurized. Entirework crews would pass into the pressurized area and often work their entire shift underpressure, essentially digging the tunnel by hand. Modern tunnel boring machines havechanged that. It is common now for the tunneling crew to spend almost all their timeworking at a safe one atmosphere pressure ( regular ambient air pressure), with smallcrews only occasionally making “Interventions” into the pressurized excavation chamberbehind the cutter head, usually to inspect or change the cutters. A recent trend ismany projects in soft ground require that the TBM be equipped with man locks so thatthe crew is properly equipped to perform hyperbaric interventions.The Occupational Safety and Health Administration (OSHA) is the federal governmentagency with the responsibility and the authority to both set and enforce workplacehealth and safety standards. OSHA has authority in every state; however, each statealso has the option of creating its own state OSHA system. If a state choses to do thisFederal OSHA must approve and monitor each states plan. For a state to get their ownprogram approved they must have safety and health regulations at least as effectiveas the federal OSHA program. 22 states currently have their own plan covering privatesector workers.The major hurdle facing tunneling companies is that the current regulations aretechnologically inapplicable and the regulations are recognized as being outdated.There exists no concerted national effort to modify the current compressed air regulationscompatible with the advances that have been made by the tunneling industry.To date Federal OSHA appears reluctant to undertake this endeavor as participantstates can require additional mandates beyond those required by the federal requirements.Further, states do not appear to be willing to establish reciprocation of approved hyperbaric operation and safety plans. Currently there is no concerted national effortby any group, Federal, State or Industry to update compressed air regulations into onecohesive standard that the Tunnel Industry can rely on or to use as a template to adaptto specific circumstances.Tunnel Boring machines are not mentioned in the Federal OSHA Regulations.Tunneling technology and hyperbaric technology have both changed greatly in theyears since the regulations were written. Even though the regulations are outdated,they still apply. The contractor must apply for and receive a variance from either Federalor State OSHA for any regulations that he does not comply with. Most of the state planshave standards that are the same as the Federal OSHA’s, some have standards justslightly different from federal OSHA and a couple have standards that are significantlydifferent from Federal OSHA. States may raise the required level of worker protectionfrom that of the federal OSHA program, but they cannot lower it below the standard ofprotection required by federal OSHA. Even if a state has their own plan, the federalOSHA rules still apply in that state and the state cannot lower the workers standard ofsafety to less than what the federal plan demands. If a contractor is working in a statethat has its own plan, then he looks to state OSHA for the regulations he must follow.If he is operating in a state without its own plan, he looks to federal OSHA for rules.All federal rules and regulations including the Federal OSHA regulations are partof the Code of Federal Regulations, or “CFR.” These rules are treated by the courtsas being legally binding as law. The CFR is divided into 50 titles with each title representingbroad areas subject to Federal regulation. The safety and health regulationsfor construction are found in title 29, part 1926. The rules specially for compressed airtunneling are found in title 29, part 1926, section 803. This would usually be written as29 CFR 1926.803.The general layout of most compressed air work involving larger diameter tunnelboring machines is to have a man lock (man lock is another word for decompressionchamber) mounted on a bulkhead near the front of the machine. The workers, usually2 or 3 at a time, enter one end of the man lock, are pressurized and then exit theother end of the man lock either directly into the excavation chamber of the TBM orinto a pressurized “motor room” (housing the drive motors for the TBM) that is directlybehind the excavation chamber (OSHA calls this the “working chamber”). If they passthrough the man lock and enter a motor room, they must next move across the motorroom to the forward bulkhead separating the motor room from the excavation chamber,and carefully open the hatch to enter the excavation chamber and begin work.On the surface, near the entrance of the tunnel, there is a compressor plant supplyingthe breathing quality compressed air to the tunnel. In some instances or asrequired by some agencies, there should also be a “medical lock.” The medical lockis a decompression chamber that is kept ready to treat decompression sickness or,perhaps, other medical emergencies if the worker also has a decompression obligationthat must be dealt with. There have been instances where a hospital equipped with amedical lock is close enough to the Project to qualify for the sites medical lock facility.It has become a common practice on larger tunnels to have a rail mounted hyperbaricevacuation shuttle that can transport workers under pressure from the tunnel tothe medical lock. This provides a means to safely transport workers with a decompressionobligation if the tunnel must be evacuated for some reason or the worker has aninjury that is too serious to deal with in the tunnel. This evacuation shuttle is not directlyrequired by the OSHA regulations, but it has become a common industry practice andcould be required under the General Duty Clause, particularly for tunnels working athigher pressures.