tailieunhanh - PCBs, MINING, AND WATER POLLUTION by Dan W. Bench B.Sc., Min. Eng.

Pollution prevention practices include low impact development techniques, installation of green roofs and improved chemical handling (. management of motor fuels & oil, fertilizers and pesticides). Runoff mitigation systems include basin infiltration basins, bio retention systems, constructed wetlands, retention basins and similar devices. Thermal pollution from runoff can be controlled by storm water management facilities that absorb the runoff or direct it into groundwater, such as bio retention systems and infiltration basins. Retention basins tend to be less effective at reducing temperature, as the water may be heated by the sun before being discharged to a receiving stream | Page 1 of 12 PCBs MINING AND WATER POLLUTION Dan W. Bench . Min. Eng. Region 8 PCB Coordinator . Environmental Protection Agency 999 18th Street Denver Colorado 80202-2466 ABSTRACT The presence of PCB-containing electrical equipment in underground mines has been documented during US Environmental Protection Agency EPA Region 8 mine inspections conducted over the last 20 years. PCB-containing electrical equipment may be found in mines throughout the world because electrical systems in mines follow the same general patterns as any other industry. The abandonment of this equipment in underground mines is likely to cause worldwide ground water contamination in mining districts. BACKGROUND Polychlorinated biphenyls PCBs are a group of 209 man-made structurally related chemicals manufactured in the US from1929 until 1977 when manufacture was voluntarily discontinued. In 1978 manufacture was prohibited and use and disposal closely regulated by the PCB regulations written by EPA as required under Section 6 e of the Toxic Substances Control Act TSCA . TSCA regulates the manufacture and use of industrial chemicals including the disposal of PCBs. It was enacted in 1976 after the discovery that PCBs had become a ubiquitous environmental contaminant that had been detected in air water soils and biosystems worldwide where they threatened human health and the environment. The discovery came in the mid 1960s when analytical equipment was sufliciently refined to detect the presence of PCBs. Unlike DDT another ubiquitous environmental contaminant which had been intentionally introduced into the environment on a large scale for insect control PCBs had been confined to limited industrial uses. PCBs were now beginning to show up all over the world. Despite the fact that manufacture has been prohibited in the US and many other countries PCBs are still authorized by the PCB regulations for use in electrical equipment primarily as dielectric fluids or contaminants in dielectric .