by Mike McLaughlin, P.E.
Coal combustion residuals (CCR) are one of the nation’s largest industrial waste streams, with more than 100 million tons produced annually. Roughly 40 percent of CCR produced is used beneficially, with the remainder disposed in landfills and surface impoundments.
Public and private waste management facilities will have new customers, as utilities that formerly operated their own disposal facilities seek reliable offsite disposal capacity. The cost of managing CCR is going up—EPA estimates the annual costs of its new CCR standards will be between $500 million and $750 million. Other estimates are as high as $2 billion.
However, before accepting CCR materials, MSWLFs should make sure they have modified procedures and otherwise accounted for the unique characteristics of CCR. CCR can have high sulfur content (on the order of 10,000 to 40,000 ppm), and under the right circumstances sulfur compounds can form hydrogen sulfide if CCR is mixed with MSW. To the extent high-sulfur wastes are disposed under conditions that can produce hydrogen sulfide, those conditions should either be controlled (or avoided), or appropriate precautions taken to manage the resulting hydrogen sulfide gas in gas collection and other systems.
There could be other reasons for segregating CCR. For example, placing CCR in a monofill areas might increase the potential for later beneficial use, especially if the materials can be kept dry. Moisture content is a critical factor affecting CCR use in pozzolanic cements, but not all ash materials are suitable for pozzolanic cement in any case. CCR also can affect structural stability of fill mass, operation of gas and leachate collection systems (e.g., through clogging with fines), and dust generation.
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