Yikes! I hadn't been aware of this ugly aspect of coal-powered generation which has lead to the devastation of a large area in Tennessee:
United States coal plants produce 129 million tons of postcombustion byproducts a year, the second-largest waste stream in the country, after municipal solid waste. That is enough to fill more than a million railroad coal cars, according to the National Research Council.
Federal studies have long shown coal ash to contain significant quantities of heavy metals like arsenic, lead and selenium, which can cause cancer and neurological problems.