Asbestos is a fact of life in the majority of hydroelectric facilities in North America. Owners and operators of these projects discuss how they are dealing with asbestos on a day-to-day basis.
By Elizabeth A. Ingram
The presence of asbestos is an ongoing issue of concern for owners and operators of hydroelectric facilities. Asbestos use was so widespread during the construction of many of these facilities, it is difficult to know exactly where this material is located in the powerhouse, which is the first step in determining how to deal with it. In addition, asbestos is also still used sparingly in new construction.
The reality is that asbestos cannot be dealt with in one fell swoop and completely eliminated from facilities. Instead, its presence must be managed on a case-by-case basis, usually while other work is being performed at a facility. For example, during the recent upgrade of the 100-year-old Boulder Canyon project in Colorado, plant owner the city of Boulder included plans to upgrade wiring and remove asbestos to reduce environmental hazards and improve safety.
Read on to learn more about this unique issue and how hydro project owners and operators are dealing with it daily.
|Work around asbestos-containing equipment in hydroelectric facilities requires specialized tools to ensure personnel safety.|
Asbestos is a naturally occurring fibrous material with high tensile strength, the ability to be woven, and resistance to heat and most chemicals. Asbestos was mined for industrial use in North America in the 1850s, even before the first hydroelectric facility was built. According to the Environmental Protection Agency, asbestos has been used in a wide range of manufactured goods, including roofing shingles, ceiling and floor tiles, paper and cement products, textiles, coatings, and friction products (such as automobile clutch, brake and transmission parts).
In hydropower plants, asbestos was used as insulation for generators and turbines and sprayed on piping and conduits. By the mid-20th century, it was used in fire-retardant coatings, concrete, bricks, pipes, gaskets, pipe insulation, ceiling insulation, fireproof drywall, flooring and roofing. Asbestos may also be present in generator brakes and control cables.
As the material ages, it begins to crumble and flake. The long, thin fibers are released into the air, where they can be inhaled by workers and cause a host of problems, such as asbestosis, lung cancer and mesothelioma. Complicating this situation is the fact that symptoms can take 10 to 40 years to develop. Asbestos has been classified as a known human carcinogen by the U.S. Department of Health and Human Services, EPA and International Agency for Research on Cancer.
According to the EPA, asbestosis is a progressive, long-term non-cancer disease of the lungs caused by inhaling asbestos fibers that causes scarring of lung tissue and makes it difficult for oxygen to get into the blood. Lung cancer causes the largest number of deaths related to asbestos exposure. Mesothelioma is a rare form of cancer found in the pleura lining the lung, chest, abdomen and heart, as well as in the peritoneum, and is almost always linked to exposure to asbestos.
Although the danger of asbestos has been recognized in the U.S. since the 1930s, asbestos regulations were not passed until 1971, when the Occupational Safety and Health Administration started regulating exposure limits. Throughout the 1970s, as understanding improved regarding the dangers of asbestos, the exposure limit was lowered, and the regulations have been tightened several times since then.
In 1989, the EPA banned all new uses of asbestos, but uses developed before 1989 are still allowed. Domestic consumption of asbestos amounted to about 803,000 metric tons in 1973 but had dropped to about 2,400 metric tons by 2005, according to the National Cancer Institute. Both OSHA and the EPA have regulations on asbestos that are meant to be compatible.
Today, worker exposure to asbestos hazards is addressed in OSHA standards for the construction industry, general industry and shipyard employment sectors. These standards require that employers provide personal exposure monitoring to assess the risk and hazard awareness training for operations where there is potential exposure to asbestos.
The facilities in which asbestos was used have aged and need maintenance or rehabilitation work. This is a problem because any activities that disturb the materials containing asbestos has the potential to release the fibers into the air. In fact, according to OSHA, heavy exposure to asbestos tends to occur in facility construction and repair, particularly during the removal of asbestos-containing materials due to renovation, repairs or demolition.
In the hydro industry, owners of most plants have engaged in asbestos abatement and containment programs. Encapsulation, the usual method, involves covering surfaces of mechanical equipment. For example, this may involve wrapping pipe insulation with canvas (lagging). Containment involves sealing off the area containing asbestos so that it cannot be damaged and released to the air.
Cleanup is a multi-step process that starts by creating a setup wherein HEPA-filtered negative air pressure machines pull fresh air into the enclosure and thus do not allow asbestos fibers into the surrounding environment. A special vacuum cleaner designed for asbestos containment typically must be used. Wet methods also may be used, which involve placing waste directly into 6 mil poly bags and wet wiping for cleanup. This work is best entrusted to a company experienced in dealing with asbestos.
How hydro is coping
What challenges are hydro plant owners facing with regard to asbestos? And how are they dealing with them? Hydro Review interviewed three plant owners to get their take and share their strategies.
Bureau of Reclamation
The U.S. Department of Interior undertook an effort to determine the presence of asbestos in all of its facilities, then extrapolated this out for the entire department, including the Bureau of Reclamation, says Peter Soeth, public affairs specialist. Through this survey, the location of typical asbestos-containing equipment and materials has been established. Asbestos has been identified throughout the power plants, including in wiring, electrical insulation, breakers, arc chutes, cable trays, floor tile, mastic, drywall, gaskets, brake shoes and ducting.
The main challenge Reclamation faces is that the presence of asbestos increases the cost of replacement projects. Conducting maintenance activities on equipment that contains asbestos dramatically increases the cost and amount of time required. In addition, there is some equipment in the hydro facilities, such as the windings of the generators, that cannot be completely cleaned and so is simply handled to prevent exposure until it can be replaced or refurbished.
For example, in May 2013, Reclamation was seeking bids to clean motor-generators at the 200-MW Mt. Elbert Pumped-Storage project in Colorado. This work must include the construction of a contaminant containment system and cleaning of the generator stator, rotor, upper guide bearing bracket and thrust bracket of contaminants including asbestos.
Over the years, Reclamation has undertaken several projects to mitigate the presence of asbestos in its hydro plants. These include:
- Hiring industrial hygiene support and certified personnel to ensure that personnel are trained to properly identify and label, handle, dispose of and/or manage asbestos in place;
- Training in-house employees in the use of protective equipment and the appropriate action if asbestos is encountered on the job;
- Managing asbestos in place where this is possible and replacing equipment when needed; and
- Adopting work practices to prevent contamination and exposure to asbestos fibers, such as the "wet" method for asbestos removal and the use of isolation bags when removing asbestos insulation from piping.
In addition, cleanup and abatement of components containing asbestos is planned into Reclamation's maintenance, equipment replacement and remodeling operations. Before working on an item or part of a facility, personnel survey and test to determine whether asbestos is present and incorporate asbestos abatement into the contract for that work, if needed, Soeth says.
Reclamation has several tips for hydro plant owners facing a similar problem. First, owners should employ industrial hygiene expertise to survey and identify asbestos-containing materials and equipment. Second, they should develop a plan to manage asbestos that coordinates facility operations and maintenance with exposure potential. Third, they should provide awareness training for employees working in known asbestos-containing facilities. Finally, they should provide training commensurate with the standards for personnel who work with equipment that contains asbestos.
Canadian provincial utility Manitoba Hydro has investigated the situation regarding the presence of asbestos in its 14 hydro facilities, two thermal plants, three converter stations, and substation buildings, underground transmission ducts and manholes, utility poles, customer service and service center buildings.
The utility has determined asbestos is present in a multitude of locations, says Edward Gatey, occupational health officer: pipe insulation, underground duct lines, cable wrap, control cables, flooring, exterior trim, soffits, arc chutes in breakers, "ebonite" board for mounting electrical devices, boiler insulation, gaskets, cable trays, asbestos-cement boards for battery rooms and as blast shields between switches, corrugated asbestos cement board for the powerhouse exterior or as roofing for other buildings, incandescent light heat shields, asbestos cement used for walls, crack filler for drywall and for smoothing transitions around flanges and valves, vermiculite in attics and cinder block walls, and fire doors.
The biggest challenges the utility faces include labeling of materials by a person competent in identifying asbestos-containing material; developing an accurate inventory that extends beyond the powerhouses (any structure built before about 1985 likely contains asbestos); time and distance (covers the entire province); sampling suspect materials not readily sampled (such as control cables and plaster); and annual inspection of installations not readily inspected (such as metal-clad breaker arc chutes).
Manitoba Hydro has included a requirement to identify, label and annually inspect asbestos in its safety management system. The utility also has an ongoing "asbestos awareness" training program so that employees understand the hazards and risks, as well as a program to identify asbestos-containing materials.
The utility removes and replaces components containing asbestos when the opportunity arises, such as during maintenance outages or when asbestos-containing materials are damaged (such as during removal of eroded transite trim on buildings). A program is in place to abate asbestos wrap on lead cables in underground systems and remove transite pipe from dips and risers. Manitoba Hydro also is working to replace breakers that have asbestos arc chutes with breakers that have non-asbestos arc chutes.
Manitoba Hydro's best advice to other plant owners is to hire competent personnel to identify asbestos-containing materials, provide a central computer database so that all employees can find out where asbestos is or might be when they enter a building to do work, and ensure building "owners" inspect and report annually with regard to damage that must be repaired and ensure that labels are in place and the inventory description is adequate for locating the material again.
Gatey indicates the utility does not have numbers with regard to the cost of dealing with asbestos, but "it has to be substantial considering the list of activities that is required (respirators, training, consumables). The cost often not considered is the health effect that may result from lack of recognition and subsequent exposure to asbestos."
U.S. Army Corps of Engineers
The Portland District of the Corps has surveyed all 12 of its hydropower facilities for the presence of asbestos, says Kenneth Duncan, environmental compliance coordinator. The asbestos survey process at a hydropower facility involves conducting a detailed site inspection where any materials that could be asbestos are sampled and identified as to whether or not they contain asbestos. The survey also includes a damage assessment to determine if any asbestos-containing materials present a hazard for employees.
The Corps tends to see asbestos in pipe insulation, gasket materials, electrical wire and concrete asbestos board (used in cable trays and as a wall material).
The Corps conducted major asbestos removal projects in the early 1990s that removed the majority of asbestos insulation and pipe insulation from its hydro plants. Today, the Corps only removes asbestos when this is necessary for maintenance of the facility. For example, at John Day Dam, the Corps is removing asbestos pipe insulation on the gate heater system at the navigation lock before replacing the pipe, Duncan says.
The biggest challenge had been the ongoing process of identifying and removing asbestos before performing work at hydro facilities, but the Corps now has contracts established for inspection and removal of asbestos.
The Corps maintains asbestos inspection-trained staff at its hydro facilities to allow quick identification of asbestos and to make sure that known asbestos is monitored to ensure worker safety.
In February 2011, the Corps sought companies that could sample for and abate asbestos and lead at 21 dams and hydroelectric projects in Oregon. Three companies bid against each other for each Corps asbestos inspection or removal task, Duncan says. The Corps has used contractors about 12 times in the past two years to conduct new surveys and remove asbestos. This has greatly improved the process and allowed the Corps to respond to problems related to asbestos-containing materials much faster.
Elizabeth Ingram is senior editor of Hydro Review.