Ε ΡRI, the research arm of the electric utility industry, announced a $7 million, five-year research program to find ways to manage . . .
The persistent PCB problem On the one hand, PCBs are a very small segment of any hazardous waste management scheme. On the other hand, they are persistent environ mental contaminants whose use has been controlled. They are the only group of chemicals specifically men tioned by the Toxic Substances Con trol Act, now five years old. Between 1929 and 1977, about 1.4 billion lb of PCBs were produced in the U.S. Although its chemical manufac ture has now ceased, 750 million lb are still in service, but only 162 million lb are associated with the electric utility industry. PCBs are used in two types of sealed electric equipment: • transformers that raise or lower the voltage of a power line • capacitors, the bread box-sized cans on utility poles that help maintain constant voltage in homes. Their good electrical properties (for capacitors) and low flammability (for transform ers) make polychlorinated biphenyls especially suitable for these uses. Of the other half of the PCBs, 3.6% have been destroyed; another 10.7% were exported. Some 21.4% are buried in landfills and 10.7% have escaped into the environment, much of that portion coming to rest at the bottom of the ocean. The EPA regulations on PCBs have caused trouble for the electric utility industry. These regulations address two types of equipment: that contain ing PCB concentrations over 500 ppm, and so-called PCB-contaminated equipment containing 50-500 ppm PCBs. Concentrations below 50 ppm are not regulated. Extent of the problem The electric utilities estimate that fewer than 22% of the 750 million lb are the responsibility of their industry. According to estimates of the Edison Electric Institute, Askarel transform 98A
Environ. Sci. Technol., Vol. 16, No. 2, 1982
ers contain 75 million lb of PCBs and PCB capacitors another 87 million lb. Askarel contains PCBs with up to 50% trichlorobenzene. Together, the 162 million lb account for essentially all PCBs in the electric utility industry. In addition, however, there are an other 262 000 lb of PCBs in other transformers. These other transform ers are filled with mineral oils. Ap proximately 10% of the utility trans formers are contaminated with PCBs in the 50-500 ppm range. This in cludes 1.9 million distribution trans formers and 25 000 power transform ers. The remainder, below 50 ppm, are
considered free of contamination. PCBs are an obvious problem for the electric utilities, though not ex clusively, since fewer than 22% of the remaining PCBs still in use are found in their industry. Other industries are said to have a PCB problem; for ex ample, the metal die-forming industry. Another use is in electrical equipment in high-rise buildings, industrial plants, and commercial operations. Here the equipment is not the responsibility of the electric utility industry per se, but rather that of other industry. The regulations have caused such concern to the electric utility industry that the Electric Power Research In stitute (EPRI) has launched its re search effort to find ways to manage this PCB equipment. A recent threeday seminar in Dallas was devoted to the detection, extraction, destruction, and cleanup aspects of the problem. Now nine years old, EPRI operates on the premise that the research it con ducts will save the utilities more money than the cost of the research. A look at the statistics from another angle reveals that there are about 150 000 PCB transformers now in service. Some 40 000 are owned by utilities. Most are relatively small, and each contains about 200-600 gal of PCB liquids. Many are found in high-rise buildings where they were installed for fire safety reasons. In practice, many are allowed to stay in service until they become faulty. Nevertheless, real problems exist. There is no reliable way to fore warn of incipient failure of trans formers; however, there is partial dis charge detection or measure of gas evolution. Using present methods, mainly incineration, disposal costs might be as much as $2000 per unit, in which case the total cost to this in dustry might be $300 million. PCB-contaminated transformers, those with 50-500 ppm PCBs, repre-
0013-936X/82/0916-098A$01.25/0 © 1982 American Chemical Society
sent a headache for the utilities. The location of these units is unknown. Finding faulty transformers is difficult and expensive. The most frequently used method of checking transformer oil is to take a sample, send it to the analytical laboratory, and have the analysis performed by gas chromatography with an electron capture detector. The cost of this analysis is $50-100 per sample, so the total cost of testing 20 million transformers could reach $1-2 billion. Eventually the contaminated oil must be drained, disposed of, or decontaminated. One of the goals of the research program is to find better and lower-cost ways of reducing PCB-contaminated transformer oil to acceptable (less than 50 ppm PCBs) levels while saving the oil. The problem with capacitors differs. There are an estimated 2.8 million capacitors in use; about 2000 of them rupture each year, spilling PCBs into the environment. EPRI research goals in this area are to find a way to predict capacitor failure and to develop a mobile device for testing soil samples for PCB contamination. Unlike transformers, there are no valuable materials to be recovered from capacitors. In capacitors, PCBs are absorbed into paper insulation; at present this solid PCB-containing material must be shredded before it is fed into an incinerator. Research on new capacitors is needed because exhaustive toxicological tests have not been made on the liquids now being used. Research is also needed for a mobile facility that could be used to destroy PCBs from the old capacitors. Most capacitors made before 1977 contained PCBs. Detection and extraction The electric utilities need a number of industry-specific detection and analytical devices. There is a need for a device to detect incipient failures in capacitors. Also needed is a portable device for testing transformer oil for PCB content in the 50-500-ppm range. Another device is needed to detect the PCB content of soils in the field so that cleanup completion could be declared when the level of PCBs is less than 50 ppm. There are prototype instruments or ideas being developed in each of these problem areas, but they are just beginning to be tested in the field. Commercial instruments are not here today. A portable X-ray fluorescence instrument for screening transformer oil for 50 ppm PCBs or less by measuring total chlorine content is being field-
tested by the Salt River Project, a utility in Arizona. Capacitors that are about to fail typically emit ultrasonic sounds. An acoustical detector (Dunnegan-Endevco) being field-tested alerts utility management to incipient capacitor failure. Another device, an infrared scanner, is being used to measure the temperature of operating capacitors. Capacitors that are about to fail may show a higher-than-normal operating temperature. Spills In the case of spills of either transformer oil after rupture or capacitor material after failure, it is necessary to
EPRI s Oil Addis: managing PCB destruction take samples of the contaminated soil and send them to a laboratory for analysis. A more expedient approach would be to have a field instrument. EPRI is working with the Oak Ridge National Laboratory on a field device for on-the-spot analysis of PCB spills. A technique using a portable infrared spectrometer looks promising for Askarel spills from capacitors. Destruction Although there are several semicommercial processes for destroying or removing PCBs in oil, none have been fully tested for treating transformer oil. A number of proposed processes use sodium in a reactive chemical to combine with the chlorine in the PCBs. A possible unknown in these latter processes is that the sodium treatment may also damage or remove some components of the mineral oil, making it unfit for continued use in transformers. Tests are under way to check this point. Sunohio, based in Canton, Ohio, has constructed a mobile PCB chemical destruction unit (ES&T, November 1980, p. 1278) and has demonstrated that its system is capable of reducing the PCB concentration in contami-
nated mineral oil to a nondetectable level. Sunohio has received approvals for the unit in EPA Regions 1, 4, and 7. Acurex Corp. has also constructed a mobile PCB destruction system and demonstrated it for EPA. Incineration on land and at sea seems to be the best option for disposal of Askarels (high-level PCB concentrations) at present. Two land-based incineration disposal sites are now licensed by the EPA—a Rollins incinerator in Texas and the Ensco (Energy Systems Co.) incinerator in El Dorado, Ark. The ocean incinerator ship, Vulcanus, is another option. The ocean incineration record with Vulcanus included EPA-approved test burns in 1974 and 1975 at designated sites in the Gulf of Mexico. In 1977, the Vulcanus incinerated the stockpile of Agent Orange, the defoliant used in Vietnam, in an area west of Johnston Island. More recently, an EPA permit, dated Oct. 23, 1981, granted permission for four separate burns in an area known as a near-biological desert, 200 miles south of Galveston, Tex. PCBs will be incinerated on Vulcanus for the first time. The Vulcanus can burn 4000 gal/h and has a holding capacity of 850 000 gal; the waste must be liquid and pumpable. Other processes for removing PCBs from transformer oil are being investigated by EPRI in lab studies. These include solvent extraction, several additional alkali metal dechlorination processes (removing chlorine atoms from the PCB molecule), electron irradiation, and super critical fluid extraction. Since a number of alkali metal processes are already under way, EPRI may sponsor scale-up of an extraction process, the most attractive of the alternative processes. Other destruction processes include Rockwell International's molten saltbath and the plasma arc process of Dr. Barton, Imperial College, Ontario, Canada. Prognosis The EPA regulations for PCBs are the classic example of a moving target. The EPA regulation has been challenged in a court case brought by the Environmental Defense Fund. The case has been remanded to the agency, which must now show cause for setting the 50 ppm cutoff. The preliminary agency response should appear in the Federal Register in March, but the final ruling is not expected until about September 1982. Originally, the cutoff value was made to distinguish between two disposal options—incineration or landfilling. —Stanton Miller Environ. Sci. Technol., Vol. 16, No. 2, 1982
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