POWER March 2014 - 49

THE FUTURE OF COAL-FIRED GENERATION
Be Prepared for Coal Ash
Regulations
The ways of Washington are murky and slow, but once the Environmental Protection
Agency finally finalizes its rules on coal combustion residuals, you'll
have to move fast to comply, so carefully consider your options today.
Brandon Bell, PE
A
little over five years ago, on the night
of Dec. 22, 2008, the residents of
Kingston, Tenn., were devastated
when a dike holding back an 84-acre ash
pond broke loose. The ash pond servicing
Tennessee Valley Authority's (TVA) Kingston
facility was holding 5.4 million cubic
yards of coal ash sludge that spread over 400
acres and damaged 42 houses. The release of
coal ash into the environment was so significant
that the consequences of the devastation
took approximately four years to clean up
(Figure 1). Even with significant cleanup efforts,
some reports estimate that as much as
500,000 cubic yards of coal ash remain in the
nearby Emory River.
Since that event, the promulgation of Environmental
Protection Agency (EPA) regulations
for coal combustion residuals (CCRs)
has been a concern of coal-fired power generators
nationwide.
Double-Edged Sword
Ash ponds were originally constructed as an
economical option to provide temporary storage
for CCRs generated from the combustion
of coal. Approximately 15% to 40% of ash
generated by coal combustion is in the form
of heavy ash agglomerations, commonly referred
to as bottom ash. This ash is too heavy
to be carried by the combustion flue gases
and thus falls to the bottom of the boiler. This
ash is particularly hot (upwards of 2,400F)
and needs to be quenched and processed prior
to handling. For this reason, most pulverized
coal boilers are designed with hydraulic bottom
ash systems to cool, crush, and convey
these heavy ash agglomerations.
At the Kingston facility, the hydraulic
bottom ash system made use of an ash
sluicing (or slurry) system to convey the
cooled bottom ash to an ash pond. Once
the ash has settled in the pond, it can be
dredged and dried, then used for secondary
purposes or landfilled.
From an operational point of view, the
ponds were designed to accommodate a
March 2014 | POWER
significant volume of ash to maintain safe
and uninterrupted power plant operations.
However, the ash in the pond contains hazardous
substances (such as heavy metals)
that can be detrimental to the environment
in a catastrophe such as the Kingston Fossil
Plant release.
Regulatory and Legal Roundabout
The EPA previously proposed regulating
CCRs in June 2010 under the authority of
the Solid Waste Disposal Act of 1970, the
Resource Conservation and Recovery Act of
1976 (RCRA), and the Hazardous and Solid
Waste Amendments of 1984 (the combined
regulations are often commonly referred to
as RCRA). Although proposed over three
and a half years ago, the regulation was never
finalized and remains in limbo.
1. TVA Kingston coal ash release.
This photograph was taken Dec. 23, 2008, a
day after the earthen containment walls holding
more than five million cubic yards of fly
ash and bottom ash sludge failed. Source: Tennessee
Valley Authority
CCRs are defined as fly ash (combustion
by-product consisting of fine particles that
rise with flue gases), bottom ash (agglomerated
coal ash particles too heavy to rise
in flue gas), boiler slag (molten bottom ash
consisting of silica and aluminosilicates),
and flue gas desulfurization (FGD) materials
(predominantly CaSOx
materials).
Fly ash consists of fine particles that are
carried through the boiler by combustion flue
gases. Because of the fine nature of fly ash,
systems designed to transport it are typically
pneumatic (vacuum or positive pressurize)
conveying systems. FGD systems are typically
designed with gypsum dewatering systems
and wastewater treatment and are not a significant
concern for CCR regulation. Bottom
ash and boiler slag that are typically handled
via hydraulic bottom ash systems and make
use of ash ponds are of significant concern
for the regulation of CCRs.
www.powermag.com
Since the introduction of the proposed
CCR regulations in 2010, the power industry
has been anticipating the release of a finalized
rule. Year after year the industry has expected
the promulgation of these regulations, but no
direction has been afforded by the EPA. That
is due to change in 2014.
On Oct. 29, 2013, in the case of Appalachian
Voices v. McCarthy, a federal judge
ruled that the EPA is required to submit a
plan and schedule for finalizing CCR regulations
within 60 days. Although this is a solid
push for the EPA to finalize CCR regulations,
it does not guarantee an expedited release of
final rules. As further incentive to finalize
CCR regulations, the ruling also requires the
EPA to review RCRA coal ash rules every
three years. The requirement for a regulatory
review of RCRA, as it relates to CCRs, could
open the door for environmental groups to
file suit against the EPA.
As this article was being written, a consent
decree was reached between the agency and
environmental groups on Jan. 29 that requires
the EPA to issue a proposed revision of its
RCRA rules no later than Dec. 18, 2014.
It is because of recent actions by the
courts that utilities still operating ash removal
systems that make use of ash ponds
need to consider alternative options for future
operations.
Subtitle C vs. Subtitle D
As part of the proposed regulation, the EPA
is considering two paths for the regulation of
CCRs (see table). The first path is using Subtitle
C of RCRA to create federally enforceable
requirements for waste management and
disposal of CCRs. The second path utilizes
Subtitle D of RCRA, which sets performance
standards for waste management facilities
that will be enforced by states that adopt their
own coal ash management programs.
Under the Subtitle C proposal, wet handling
of CCRs, including the use of coal ash
ponds, would be phased out. The Subtitle D
path would require existing coal ash ponds
47
http://www.powermag.com
POWER March 2014

Table of Contents for the Digital Edition of POWER March 2014
