12/24/2018

‘Twas the night before Christmas – well, not quite. It was on December 22, 2008. On that day, the Tennessee Valley Authority (TVA) Kingston Fossil Plant experienced a collapsed dike, resulting in 1.1 billion gallons of wet coal ash spilling into the environment.

Coal ash? Coal ash is the byproduct of electricity generated by coal-fired power plants. Sometimes referred to as coal combustion residuals or CCRs, this material is produced primarily from the burning of coal and includes numerous by-products, such as:

• Fly Ash, a very fine, powdery material composed mostly of silica made from the burning of finely ground coal in a boiler.
• Bottom Ash, a course, angular ash particle that is too large to be carried up into the smoke stacks, so it forms in the bottom of the coal furnace.
• Boiler Slag, molten bottom ash from slag tap and cyclone type furnaces that turns into pellets that have a smooth glassy appearance after it is cooled with water
• Flue Gas Desulfurization Material, a material leftover from the process of reducing sulfur dioxide emissions from a coal-fired boiler that can be a wet sludge consisting of calcium sulfite or calcium sulfate or a dry powered material that is a mixture of sulfites and sulfates.

Coal ash is one of the largest types of industrial waste generated in the United States. According to the American Coal Ash Association’s Coal Combustion Product Production & Use Survey Report, nearly 130 million tons of coal ash was generated in 2014 (that’s the latest tabulated statistics). According to U.S. EPA, there are over 1,000 operating coal ash landfills and ponds and many hundreds of “retired” coal ash disposal sites.

Aside from environmental concerns, coal ash contains many toxic substances that can negatively impact human health. Employees working in coal-fired power plants or populations near coal ash waste sites are at risk of inhaling coal ash dust. Coal ash dust is sometimes referred to as particulate pollution and its dust particles can cause adverse conditions to the lungs when inhaled. As such, workers have an increased risk when they inhale coal ash dust particles. The smaller the coal ash dust particle, the deeper the potential to be inhaled into the lungs. When particles get so small – less than 10 micrometers (microns) in diameter – they can bypass the body’s natural defenses and reach the alveoli: the tiny sacs at the very distal regions of the lungs where oxygen is transferred into the blood stream. As a result, the alveoli can become physically impaired, rendering them incapable of allowing their vital gas exchange function. Thus, the body will not receive the required oxygen that is necessary for the various parts of the body. This is referred to as hypoxia and can cause severe illness including death. Typical diseases associated with damaged alveoli include asthma, chronic bronchitis and emphysema.

Furthermore, coal ash dust can be absorbed through the blood-brain barrier resulting in swelling of the brain. Regardless of route of exposure (i.e. inhalation, ingestion, etc.) the toxicity from coal ash can cause harm to major body parts such as the brain and lungs (already mentioned) and heart, liver, kidneys, stomach and intestines. Thus, individuals working near coal ash surface impoundments or landfills are at increased risk for many serious health problems.

Typical metals contained in coal ash include: lead, cadmium, chromium, arsenic, mercury, boron (which is technically a metalloid), molybdenum, and thallium. These materials are known to be extremely toxic to humans and are classified as carcinogens. Damage to kidneys, bones, bladder, intestines, stomach, liver

and brain are targets for these substances (while these materials are associated with disfunction to the many organs listed here, no single contaminant targets all these organ systems).

Another contaminant associated with coal ash is silica. When silica is inhaled, fetal lung disease or silicosis can develop. Furthermore, exposure to silica can cause loss of appetite, poor oxygen circulation, breathing complications and fever. And chronic exposure of silica can cause lung cancer.

From a worker health aspect, organizations such as OSHA and the American Conference of Industrial Hygienists (ACGIH) have established worker health exposure limits, known as permissible exposure limits (PELs) and Threshold Limit Values (TLVs). These limits are workplace air concentrations, typically expressed as milligrams per cubic meter, and have been established so that employers have the responsibility to ensure workers do not work a full shift (8-hour day) where such conditions exist. When concentrations reach such levels, the employer is responsible to reduce exposures by installing engineering controls (ex. ventilation) or administrative controls (ex. prudent work practices, using shorter work periods, etc.). And if these controls are not feasible or applicable, then personal protective equipment such as wearing respirators must be established.

From an environmental perspective, the EPA established the first regulation for controlling coal ash with respect to public health. It is known as the Disposal of Coal Combustion Residuals from Electric Utilities and was promulgated in April 2015. It provided a comprehensive set of requirements for the safe disposal of coal ash from coal-fired power plants while implementing technical requirements for CCR landfills and surface impoundments under subtitle D of the Resource Conservation and Recovery Act (RCRA): the nation’s primary law for regulating solid waste. In addition, it addresses the risks from coal ash disposal, including leaking of contaminants into ground water, blowing of contaminants into the air as dust, and catastrophic failure of coal ash surface impoundments. Additionally, the rule sets out recordkeeping and reporting requirements as well as the requirement for each facility to establish and post specific information to a publicly-accessible website.

As a method to minimize coal ash disposal into landfills, the regulation supports the responsible recycling of CCRs. How beneficial is coal ash recycling? Recycling coal ash conserves natural resources and saves energy. In many cases, products made with coal ash perform better than products made without it. For instance, coal ash makes concrete stronger, less permeable and more durable. It also reduces the need to manufacture cement, as it acts as an excellent partial replacement in concrete production, up to 50%! This results in significant reductions to CO2 greenhouse gas emissions.  Other beneficial recycling uses include: mixing coal ash with native soils for road stabilization and other in-ground structural fill uses such as a reclamation product in oil fields and numerous other applications where it has an economic value.

Sounds like there are some great environmental solutions when it comes to coal ash as a byproduct. Nevertheless, we cannot forget that handling this material requires a concerted effort by the employer to ensure workers and the public are properly protected. Such controls – as discussed earlier – are quite feasible to implement, thereby providing effective means for managing coal ash.

The only thing worse than a liar is a liar that’s also a hypocrite!

Tennessee Williams Jr.