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--> Milwaukee Water Pollution Abatement Program: Underground Safety—Dealing With Osha John Ramage Abstract Underground construction is fraught with hazards. Although many of these can be anticipated, sometimes workers' own choices put them beyond the protection of countermeasures. The Milwaukee Water Pollution Abatement Program (MWPAP) can attribute three of its six fatalities to such a choice. Guidance in structuring a safe underground work place can be found in regulations published by the Occupational Safety and Health Administration (OSHA), the Mine Safety and Health Administration (MSHA), and other agencies with a similar mission. OSHA regulations have improved recently, but the industry still requires better understanding and definition of responsibilities for such issues as tunnel classification and control of a multiemployer work site. Those involved in tunnel construction should work with OSHA to establish clearer direction on these issues. Background MWPAP began in 1977 as a program imposed by the federal and state regulators that encompasses the 450 square mile Milwaukee metropolitan area. The work consists of upgrading two waste water treatment plants, as well as establishing a large-diameter, in-line storage interceptor system and a program to relieve combined sewer overflows in the Milwaukee metropolitan area. MWPAP is now 97 percent complete, with completion expected in the fall of 1995, a year ahead of schedule.
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--> The total cost of MWPAP is $2.29 billion. The program comprises 324 separate construction contracts,1 and construction costs represent $1.6 billion of the total cost. The underground component, with construction costs of approximately $900 million, consists of 20 miles of 17-to 32-ft-diameter rock tunnels lying 300 ft below the ground surface, 24 drop shafts and approach channels connecting to that deep system, and 62 miles of small-diameter (i.e., 60 to 144 inches) near-surface collector tunnels at depths of 30 to 100 ft below the surface. Organization of MWPAP The owner of MWPAP is the Milwaukee Metropolitan Sewerage District (MMSD), which was the first special service agency in the United States. CH2M Hill is the program manager and as such is responsible for planning, design, construction management, cost and schedule control, and claims management or mitigation. All construction contracts were procured using the normal public works bidding process. Construction contracts are between MMSD and the construction contractor. Eighty-eight engineering firms work under direct contract to CH2M Hill, with a maximum of 650 personnel. At the height of construction in the late 1980s there were 75 active construction contracts, employing 1,200 construction personnel. The controlling regulatory code for safety is the federal OSHA code. Underground construction is governed by Subpart S, "Tunnels and Shafts, Caissons, Cofferdams, and Compressed Air," which was revised in 1989. Subpart K of the OSHA regulations, "Electrical Code," was another critical regulatory component for the program. Safety on MWPAP was also under the review of the Wisconsin Department of Industrial Health and Labor Relations. The roles and responsibilities of team members are well defined and have been throughout the program. The owner, MMSD, alone has the authority to shut down work for any reason. MMSD also committed to fund, train, and have available the rescue team for all underground contractors. To meet this commitment, the Milwaukee Fire Department assembled three full rescue teams staffed through the Milwaukee metropolitan area that meet the OSHA 30-minute response criterion, with more than adequate backup for the second team. Finally, and most importantly, the prime construction contractor (i.e., the organization responsible for the work on site) carries the overall responsibility for work-site safety. 1 MWPAP's 324 separate construction contracts have been distributed across the years of the program's existence.
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--> The program manager, as one employer on a multiemployer work site, has the responsibility to train its own staff for their work activities underground. This also requires an understanding of the prime contractor's safety program and an implementation of appropriate components of the program by the program manager's staff. All personnel are to report their safety concerns to the contractor and the program's on-site representative (usually the resident engineer). Finally, each individual has the responsibility to take action as a prudent professional if danger appears imminent. Program Safety The subsurface environment in the Milwaukee metropolitan area has had a significant impact on underground construction and associated safety requirements and programs. The metropolitan area lies at the confluence of three rivers as shown in Figure 1. These rivers are surface expressions of deeply carved glacial valleys. Since the last glacial period, these valleys have been filled with a wide range of deposits ranging from dense glacial till to sand and gravel alluvial deposits and highly organic marsh deposits. While construction challenges occurred on the deep rock tunnel component of MWPAP, the major challenges occurred in work conducted in materials deposited since the last glacial period. Three major elements challenged the construction team. First, since most of the near-surface tunnels constructed on MWPAP followed the paths of the three rivers in the area, ground water levels were close to the surface. This required soft-ground tunneling methods, as shown in Figure 2, that control the inflow of water to minimal levels. Second, the variable nature of these subsurface deposits required ground support systems that were robust, with the flexibility to support widely varying loading conditions. This was particularly crucial in the soft organic marsh deposits. Finally, the most significant challenge of all was dealing with the potential of methane produced from the natural decay of organic materials in the marsh deposits. These deposits were the source of the methane that fueled a 1988 explosion. Safety Record MWPAP has had six fatalities in over 20 million hours of underground work. One worker fell in a shaft, another was hit on the head by falling debris, and a third was caught in a conveyor. The last three fatalities resulted from the 1988 methane explosion. There were no citations for the first three, but litigation and federal action continue in the case of the explosion.
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--> Figure 1 Metropolitan Milwaukee area map showing the confluence of the Menomonee, Milwaukee, and Kinniokinnic rivers.
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--> Figure 2 Soft-ground tunneling method used to control the inflow of water.
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--> The Regulatory Environment And The Team's Response The OSHA Code, Subpart S, in force through most of the program's underground construction, did not include the current classification system, that provides definitions classifying tunnels as nongassy, potentially gassy, or gassy. In addition, before 1989, Subpart S contained only minimal language on air quality and ventilation. It required mechanical ventilation, a reversible ventilation system, 30 ft/min of airflow in the tunnel, 200 ft3/min per worker, and mandatory shutdown and evacuation of workers at 1.5 percent (i.e., 30 percent of the lower explosive limit [LEL]) or higher concentrations of flammable gas, with no return to work until concentrations diminished to less than 1 percent (i.e., 20 percent of the LEL). The OSHA regulations also required that evacuation plans be developed and made known to the employees and that electrical equipment conform to the requirements of Subpart K. These requirements set the minimum standards for underground safety. In December 1987, a contractor ran into methane while mining through a highly organic soft clay. Several shutdowns occurred. Responding to the contractor's concern, CH2M Hill conducted a major investigation to determine the potential occurrence of methane in this environment. The findings, shared with all underground contractors, led the program manager to take a proactive approach to the potential methane hazard by modifying all of the contracts to establish stringent, specific safety requirements. They took the best, most stringent requirements from several sources, including California OSHA, MSHA, and the federal OSHA. From these requirements they crafted precise language for the seven tunnel contracts in the soft organic clay environment. The contract modification required the following: ventilation 24 hours a day, using Class I, Division 1 fans for the main ventilation system (Subpart K, Section 1926.449, "Electrical Code, Classification of Hazardous Work Space"); an airflow increase from 30 to 60 ft/min; continuous monitoring at the heading with warning broadcast at 10 percent of the LEL and shutdown and evacuation at 20 percent (recall that Subpart S at the time required shutdown and evacuation at 30 percent of the LEL); and the conformance of all electrical components on the TBMs to Class I, Division 2 requirements (also from Subpart K). Contractors were required to develop a detailed, formal training program and a detailed evacuation and recovery plan should a shutdown occur.
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--> CH2M Hill performed a detailed fault-tree analysis of failure mechanisms in the underground construction environment to establish redundancy priorities. (A fault tree is a logic diagram that allowed CH2M Hill to reason through the chains of circumstances and events that lead to the failure mechanisms.) Ventilation proved most critical in providing a safe working environment. The team required 24-hour ventilation; fully reversible, explosion-proof fans; and air velocities greater than those required by OSHA (see Figure 3). The next redundancy priority was early detection. The team required continuous monitoring and early detection and warning. Shutdown and evacuation were the third redundancy priority, and comprehensive training was the fourth. Class I, Division 2 electrical components were considered the fifth level of redundancy. Preventing the environment from becoming hazardous was the first objective of the contract safety program. If prevention proved impossible, getting the workers out and the power off before it became hazardous was the backup. The Event On November 10, 1988, the contractor started the morning shift and quickly encountered a concentration of methane in excess of 20 percent of the LEL that shut down the TBM. The 11 people in the tunnel at that time evacuated safely. The contractor's evacuation and recovery plan required that the superintendent account for all workers who had been in the tunnel and then de-energize the tunnel, reverse the fan on the main vent line, and monitor the return air, waiting a minimum of one hour or until he or she could no longer detect a flammable mixture in the return air, whichever period of time was longer, before reentering the tunnel. Instead of following the evacuation and recovery plan, the superintendent, the safety engineer, and the shift foreman—the three most experienced people on the contractor's team—reentered the tunnel after 45 minutes. They neither reversed the ventilation system's air flow nor monitored the methane levels in the return air, they never shut off the power, and they did not wait the minimum hour. Five minutes after they reentered the tunnel, an explosion killed them. The Fallout Despite the belief of the MWPAP team that program roles and responsibilities are well established, legal determination of responsibility for the explosion remains unresolved. OSHA continues to pursue action against CH2M Hill.
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--> Figure 3 Tunnel ventilation system using fully reversible, explosion-proof fans.
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--> The consequences for the contractor included convictions for negligent homicide at the state level and for criminal violation of OSHA regulations at the federal level. The contractor's total expenses for litigation, recovery of the tunnel, and returning to work ran over $7 million. The contractor also was disqualified from a bid that he had essentially won for work on the Los Angeles subway system. CH2M Hill was charged with 47 willful violations of OSHA regulations, with a fine of $10,000 per violation. Twenty-seven of those violations were for the lack of explosion-proof light bulbs, as required in Subpart K, in the string leading from the shaft to the heading. OSHA has taken the position that the hazardous classifications under Subpart K, which were intended for work spaces such as paint shops and manufacturing facilities, apply to underground construction. CH2M Hill was also charged as having control over the construction work site. Their cost thus far has exceeded $2 million. Personally, the author has spent much time giving depositions to federal lawyers, state lawyers, and insurance company lawyers. He has been a witness in the criminal proceedings. And the U.S. Attorney from the southeastern district of Wisconsin believed that the author sat down with the contractor's project manager after the explosion and drafted the evacuation plan. The author testified before a federal grand jury, as the Department of Labor and U.S. Attorney explored a possible corporate and personal indictment for criminal violation of OSHA regulations. Fortunately there were two engineers on the grand jury. One of these, who had worked in a manufacturing facility, observed that using Subpart K hazardous classifications in the underground environment was inappropriate. Criminal indictment of CH2M Hill and the author was not pursued. Subpart K's hazardous classifications assume that work must be conducted in a hazardous environment. However, the MWPAP team's approach to the underground environment, demonstrated by their contract modifications in the face of a high probability of methane being encountered, was to detect hazards early, shut down work, and evacuate the tunnel before the environment became hazardous. From that perspective, Subpart S and the MWPAP team's contract modifications were far more stringent than Subpart K. Five years later, CH2M Hill is still embroiled in legal repercussions. On August 25, 1993, upon CH2M Hill's formal appeal, a Department of Labor administrative judge dismissed all charges, saying in his decision that it was unequivocally clear that the program manager did not control the work site. The contractor even asserted under oath that he controlled the work site and assumed all responsibility for safety. However, OSHA filed an eleventh-hour appeal and continues to insist that CH2M Hill controlled the work site, despite the contractor's insistence to the contrary. The case will go before the OSHA Review Commission and quite possibly to the U.S. Appeals Court and the Supreme Court. CH2M Hill expects that a resolution of the case is three or more years away.
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--> Lessons Learned The following lessons can be drawn from the CH2M Hill experience with the methane explosion on the MWPAP. First, in underground construction, all responsibility for and direction of safety must be centered in a single entity or organization. That entity must have a well-documented safety plan and must ensure that all involved are properly trained in safe practices and responses to contingencies. All employees on the project must follow the safety program. The responsible entity must exhaustively document all its efforts to ensure safe practices. Second, those involved in underground construction have a number of issues to resolve with OSHA. Subpart S was revised in 1989, after the MWPAP methane explosion, to provide definitions for tunnel classification as nongassy, potentially gassy, or gassy. The revisions also require a warning when explosive gases reach a level of 10 percent of the LEL and evacuation at 20 percent, as was required by the revised contracts on MWPAP. Finally, the revisions add details concerning ventilation requirements and training and evacuation plans. However, despite the revisions providing the definitions, OSHA has shown no willingness to classify tunnels. Those involved in tunnel construction must work with OSHA to determine who is responsible for doing so. Also, the question of whether the hazard classifications of the Electrical Code apply underground must be resolved. Finally, in a multiemployer work site, what does control of the work site mean? Roles and responsibilities of the various parties to a project must be better defined. In the end, safety is an attitude that must be maintained continuously. Those involved in an underground construction project must work together as an integrated, coordinated, and committed team with safety as a primary focus; otherwise, accidents will happen. Discussion In response to participant questions, John Ramage added the following points of clarification. Before the methane explosion, there had been one other shutdown because of a high methane concentration. Interpreting the question further, he added that there is not really any way to prevent workers from making bad decisions, such as the one to go back into the tunnel, either with regulations, program plans, or training. The decision to go back into the tunnel was made by the safety engineer, who had returned two days before the incident from a week-long training course given by MSHA.
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--> He was an employee of the contractor and had the authority to make that decision. The safety engineer was one of the three who reentered the tunnel. Following the question period, Ted Petrie, who is a division manager for the Department of Engineering at the Department of Energy (DOE), described the process by which DOE selects the regulations to be imposed contractually at the Exploratory Studies Facility (ESF) at Yucca Mountain and named the agencies involved in the safety oversight of the program. The following are the regulations from which DOE has selected the health and safety requirements to be met at the ESF: the State of California Tunnel Safety Orders, the OSHA Orders, the MSHA Orders, the State of Nevada Health and Safety Standards, and the State of Nevada OSHA regulations. From these various sources, DOE selects the most stringent requirements (i.e., the ones providing the most protection) in each category and imposes them contractually upon the prime contractor and, through the contractor, upon all parties working on the ESF. The enforcement agency with jurisdiction over the ESF is the State of Nevada OSHA. That agency has formal inspection authority at Yucca Mountain. DOE also has a memorandum of understanding with MSHA, through which MSHA will provide, upon request, less formal design review and inspections to assist DOE in ensuring safety at the Yucca Mountain ESF.
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--> Bibliography Goodman, G.V.R. 1988. An assessment of coal mine escapeway reliability using fault tree analysis. Mining Science and Technology. 7:205-215. MSHA. 1986. Fault Tree Analysis. Safety Manual Number 8. U.S. Department of Labor, Mine Safety and Health Administration.
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