On December 19, 2014, the Environmental Protection Agency (EPA) finalized national regulations to provide for the safe disposal of coal combustion residuals (CCRs) from coal-fired power plants. CCRs, generically referred to as coal ash, also includes by-products such as fly ash and bottom ash. Fly ash in particular has been designated as a non-hazardous material, and many of the groups whose input influenced legislation are now focused on reforming the regulations on disposal to be more lenient, promoting responsible recycling of fly ash, such as ASTM C618-grade fly ash processing. In place of disposal, several safe uses for reprocessed fly ash have been distinguished in the new regulations, and are estimated to result in billions of dollars in savings.
Since publication in the Federal Register on April 17, 2015, states are now required to adopt the federal minimum criteria and revise their Solid Waste Management Plans (SWMPs) accordingly for EPA approval. The actual effective dates for each part of the rule varies from 6 months to 30 months.
Dust Solutions, Inc. (DSI) has been closely monitoring the technical requirements and implementation timelines that pertain to air quality criteria and fugitive dust protection. Two key items that have a six (6) month implementation timeline include:
DSI has experienced a recent uptick in inquiries regarding dust suppression for coal and fly ash applications as owners and operators work towards meeting these requirements. For fly ash handling, there are several new criteria that may require adjustments to owner and operator’s operating procedures. Controlling fly ash can be very challenging due to two physical properties of the material. First, fly ash is inherently moisture repellent, making the dust particles dry and potentially mobile. For this reason, many dust suppression methods that use water or chemicals to wet the material are not effective. In addition to not suppressing fly ash dust, suppression methods that add moisture also have the potential to harden the material prematurely, resulting in handling problems and the inability to achieve the required degree of compaction for future use. The second challenge is that fly ash particles are extremely lightweight and fine, measuring in size of approximately 5-12 microns, whereby the material is easily taken airborne and can remain in the air for an extended period of time, potentially blowing into neighboring areas.
DSI’s dry fog dust suppression systems are effective where other technologies are not due to the unique ultrasonic, air-atomizing nozzles that creates fog droplets 1-10 micron in size. Scientific research has shown that for effective dust suppression to occur, dust particles and the binding material (fog droplet) must be comparable in size. Dry Fog systems produce the smallest droplet and achieves the closest match to fly ash in particulate size enabling a more effective agglomeration to occur. The minimal amount of water used also prevents over-wetting of ash, reducing mess, the need for drying, and assurance that ash compaction specs are met.
Find answers to frequent questions on how the coal ash rule addresses fugitive dust here: http://www2.epa.gov/coalash/frequent-questions-coal-ash-rule#11.
Read about how the final rule addresses operating criteria in Section 257.80-Air Criteria (page 179): http://www.gpo.gov/fdsys/pkg/FR-2015-04-17/pdf/2015-00257.pdf.