Turns out toxic heavy metals are, um, toxic

EPA determines coal waste raises cancer risk

Posted by David Roberts at 11:25 AM on 07 Sep 2007

Read more about: energy | coal | toxics | US EPA

The waste from burning coal -- coal combustion products, or CCPs, like coal ash and boiler slag -- contains toxic heavy metals like mercury and cadmium. But don't worry, the coal industry says that the concentrations aren't high enough to do anyone harm. Taking the coal industry's word for it, the U.S. EPA decided in 1993 and again in 2000 not to regulate CCPs as hazardous waste.

As a consequence, the coal industry isn't all that careful with CCPs. Using a composite liner under CCP landfills can reduce the seepage of heavy metals into the water table, but eh, it's kind of expensive, so why bother? Most don't (sub rqd.):

EPA's own assessment of the nation's 600 coal combustion waste sites in 2000 found that 43 percent of landfills and 74 percent of surface impoundments were unlined.

Now, however, a draft EPA report (PDF) says that, oops, CCPs are dangerous after all:

People exposed to arsenic groundwater contamination from unlined coal ash landfills face a cancer risk 50 times greater than is considered safe under federal rules, the report said.

The report has been opened to public comment; the EPA is trying to figure out whether and how to regulate CCPs.

Special bonus fact: the cleaner coal's air emissions are, the more ash it produces. Sweet.

For story: Turns out toxic heavy metals are, um, toxic
2 Comments | Post a Comment

Excellent post, David

I was waiting for somebody to talk about this ... a major component of any coal power plant is to handle cooled bottoms from the power boiler. There's a bunch of relatively benign stuff in there like silica (cough, cough), alumina, and iron but the main offenders are mercury, cadmium, selenium, barium, chromium, zinc, lead, arsenic, molybdenum and other trace metals; some of it it radioactive.

The EPA wants more folks to use it as a filler for concrete and asphalt, since that at least renders the CCP less mobile in the environment. However, ash and slag handling is expensive, more expensive than using ... you guessed it, dirt like lime, sand, gravel, and stone.

Oh well.

Interesting factoid: if the bottom slag drain on a cyclone boiler fouls up and clogs, the entire power plant would blow up. They even have a video camera to make sure it still flows. That's why scrap tires aren't used anymore for boiler fuel, since the stainless steel belts clogged the slag drains.

Onward through the fog

by Sam Wells at 2:30 PM on 07 Sep 2007

Nearer than you might think

CCPs have been reused in construction materials for several decades. The quantities are large: According to the American Coal Ash Association, about 50 million tons -- forty percent of all CCPs produced in 2005 -- were reused, with more than 26 million tons going into construction materials.

CCPs work their way into all sorts of homebuilding materials and other products destined for human usage. 16 million tons go into concrete and grout. Gypsum is created from the coal desulpherization process and is said to be "96 to 99 percent pure"; eight million tons of it are used to manufacture gypsum wallboard. 1.5 million tons are used as blasting grit and roofing granules.

CCPs have been used to manufacture cinder blocks, bricks, and asphalt road surfacing. They have been used in drinking water reservoirs, such as the Seymour-Capilano Filtration Plant that serves Vancouver. They are spread on roads to melt snow and ice. The have been tested on agricultural soils, but "regulators are reluctant to allow the use of soil amendments that contain mercury, no matter how stable."

The industry hopes to increase the CCP reuse rate to 50 percent and is looking into applications such as "plastics and thermoplastics, paper, pharmaceuticals, food, adhesives, and paint."

Ped Shed Blog

by Laurence Aurbach at 9:20 AM on 08 Sep 2007

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