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small brand Polychlorinated Biphenyls Management

NorthWestern Energy routinely tests any equipment that may contain polychlorinated biphenyls (PCBs) – an organic chlorine compound once widely used as dielectric and coolant fluids in electrical equipment. PCBs are highly toxic and classified as a persistent organic pollutant and as a carcinogen. Because of this, the U.S. Congress banned the production of PCBs in 1979, followed by a ban endorsed by the Stockholm Convention on Persistent Organic Pollutants in 2001.

We test dielectric fluid in any equipment manufactured before the PCB ban or that might contain oil-filled components (e.g., bushings on a transformer) that are known or suspected to have been manufactured before to the PCB ban. As required by corporate policy, we label any tested equipment found to contain PCBs and replace or refurbish the equipment if necessary.

PCB tagging codes

Field test kits, known as Clor-n-oil tests, are carried and deployed by employees in the field to provide real-time information to assist in directing emergency cleanup work or to provide information during the initial stages of project planning. The field tests are followed by appropriate confirmation sampling and analyses by an accredited laboratory.

Case-in-Point: Strong thunderstorms swept through Letcher, S.D. in May 2018, bringing down numerous poles, including one supporting an old transformer that happened to contain 100 parts per million (ppm) of PCBs. The lid of the transformer was damaged, and 22 gallons of oil was released. Responding employees, following established spill training and protocol, used a Clor-n-oil test kit and determined that the oil was positive for PCBs. Cleanup efforts began and excavated materials were consolidated into appropriate containers, then transported to a local warehouse for storage in a designated PCB storage area.

A confirmation sample of the oil was sent to a lab, and upon receiving validation of PCB levels, the release was reported to the South Dakota Department of Environment and Natural Resources (SD DENR) and the Environmental Protection Agency (EPA).

NorthWestern Energy, working in cooperation with regional EPA, sampled the excavated material and had it reanalyzed for PCB content and Total Petroleum Hydrocarbons. Using these sample results and soil property data, calculations were developed showing anticipated PCB concentrations in the soil at various stages of oil saturation. Utilizing an EPA-approved saturation value of 70%, the calculations showed that anticipated PCB concentrations in the affected soil at the spill site were less than 50ppm. EPA granted NorthWestern approval of the formal spill cleanup report, as well as granting approval for disposal of the effected/excavated material in an appropriately licensed municipal landfill located near Mitchell, S.D.
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