Safely Managing and Securing Coal Combustion Residuals

Because of its abundance and proven effectiveness as an energy source, coal is currently used to generate around 40 percent of the electricity in the U.S., and is projected to be a major component of the energy mix for the foreseeable future. When coal is burned to make the steam that drives electricity generators, ash is the noncombustible mineral matter left behind. Ash is the most prevalent of Coal Combustion Residuals (CCRs) taking the form of fly ash (fine, smaller particles collected in air emission controls such as electrostatic precipitators) or bottom ash (coarse larger particles that settle at the bottom of boilers). Depending on the coal type, the amount of ash that remains is 10 to 30 percent of the coal that is burned as fuel.

 

Some metals that occur naturally in coal in trace amounts (arsenic, mercury and lead) remain in the ash. By using proper management procedures, the metals are contained within ash management facilities on site at the power plants. The two most common types of ash management facilities are landfills, which are used to dispose of dry ash, and surface impoundments, also called wet ponds (in which ash settles at the pond bottom). Ash collected for beneficial reuse is in some cases stored in dry ash silos. Coal ash surface impoundments are a standard practice for managing fly ash and bottom ash.

There are many beneficial uses for fly ash, including use in concrete, cement, road building and gypsum in wallboard and agricultural applications. A strong market for recycled fly ash and power plant synthetic gypsum has developed over many years, and new uses are being explored.  Bottom ash recycling is more problematic due to its lower capacity for pozzolanic reactions.

On April 17, 2015, the EPA published its final rule establishing comprehensive regulations for the disposal of CCRs from coal-fired power plants under subtitle D of the Resource Conservation and Recovery Act (RCRA), classifying CCRs as nonhazardous solid waste. The EPA issued the final rule under a self-implementing approach because EPA lacks the authority under subtitle D of the RCRA to require states to issue permits in this context. Therefore, EPA requires the minimum federal criteria to be administered by each owner and/or operator that manages CCRs in surface impoundments and landfills.

The rule applies to three categories of CCR management

1. Inactive facilities: these impoundments or landfills stopped receiving CCR waste before October 19, 2015
2. Active or existing facility: a management unit that is in operation on October 19, 2015, and
3. New CCR facility: a unit that receives CCR or starts construction after October 14, 2015.

Inactive facilities contain by far the most CCR material.  Closure must be completed by April 17, 2018 in order to avoid technical requirements for closure systems.  Active facilities and inactive facilities failing to meet the closure deadline will be subject to the technical requirements for closure including development of an approved closure and post-closure care plans as well as install a groundwater detection network and institute corrective action if required.  New facilities will be required to meet the siting criteria and technical requirements for bottom liners and cover systems in addition to the requirements for existing facilities.

REUSE

Historically, power plants have managed CCR in impoundments and landfills proximate to the point of generation which was the least expensive option allowable under the rules at the time, i.e., there was an incentive for this practice.  The new EPA technical requirements for impoundments and landfills may change this equation to favor beneficial reuse.  The North Carolina Coal Ash Management Commission (CAMC) looked at reuse methods that would use the maximum amount of ash, make economic sense, and be environmentally sound.  The CAMC determined that two scenarios fit these criteria, i.e., use of CCR:

1. In concrete products
2. As structural fill

Drawbacks to using CCR for the stated purposes have been the carbon content of CCR is greater than 4% limiting its utility in concrete and the susceptibility of ash road base to develop reflection cracks. Other potential uses listed in the study included use in flow able fill mixes, mine reclamation, brick manufacturing, Rare Earth Element (REE) extraction, agriculture, waste stabilization, and snow/ice control.

A key to safe and secure CCR management in impoundment systems is ensuring the integrity of the containment system. The key is to develop a safety program which is comprehensive and includes inspections, reporting, analysis, regulatory compliance, emergency response preparedness, routine maintenance and vegetation-control standards. Inspections of dams and dikes are critical components and are conducted on a regular basis – at least annually by professional dam safety engineers and at least weekly by trained plant personnel. In addition, inspections are performed after unusual events such as storms.

The inspections provide assurance that structures are sound and that action is taken, as needed, based on the findings. Safety inspections include numerous checklist items. Specific items vary from site to site but may include observations of such things as pond levels, weather conditions, rainfall since the prior inspection, instrument readings, conditions of slopes and drains, erosion, animal damage, ant hills, alignment of retaining structures and more. Dam safety engineers assess instrument readings, inspect any maintenance or remediation performed since the previous inspection, check the status of work recommended at prior inspections, ensure that the posting of emergency notification information is up to date and evaluate any items noted during plant personnel inspections.

So how can we help? 360factors, Inc. is a cloud based Enterprise Risk and Compliance Management Technology and Services Company. 360factors helps companies improve business performance by reducing risk and ensuring compliance. 360factors’ flagship platform, Predict360, uses unique mapping and cognitive computing technologies to provide regulatory insight, predict risks and drive operational excellence.

Rosengarten, Smith & Associates our EHS consulting services division, offers a wide range of services in regulatory compliance and permitting (air, water, and waste), site investigation and remediation, environmental and dredge material sampling and evaluation, and health, safety and risk management services. RSA maintains a staff of experienced key personnel including registered professional engineers, geologists, and health & safety specialists. For over 27 years, RSA has completed projects in 38 states across the United States and in four other countries for Fortune 500 companies, lending institutions, and small businesses.

Remain up-to-date on industry news / updates through our  Twitter & Linkedin profiles.

*All images are property of their respective owners.