POWER October 2011 - 78

COAL ASH MANAGEMENT
Constructing Maryland's First
Permitted Landfill for Coal
Combustion By-products
Constellation Power Source Generation Inc., which owns and operates three
coal-fired power plants in Maryland, has contracted with Charah Inc., an
ash management company, to build a landfill to strict environmental requirements
for the disposal of its plants' coal combustion by-products
that can't be recycled for other uses.
By Angela Neville, JD
C
oal-fired power plants produce approximately
40% of the electricity generated
in Maryland. Constellation Power
Source Generation Inc. (CPSGI), an affiliate
of Baltimore-based Constellation Energy,
owns and operates three of these plants that
help meet the growing demand for electricity.
Although more than half of the coal combustion
by-products (CCBs) produced by these
three plants is recycled for reuse in products
such as cement and concrete, not all can be
reused due to a lack of market demand. The
remainder is placed in landfills permitted to
dispose of such materials.
Overview of Coal Combustion
By-products
Approximately 43% of CCBs were recycled
for " beneficial uses " in 2008, according to the
American Coal Ash Association. The remainder
were landfilled, placed in mine shafts, or
stored on site at coal-fired power plants.
The University of North Dakota has extensively
researched the characteristics of
different types of CCBs typically produced
by coal-fired power plants. Here are the main
types of CCBs the university has identified:
■ Boiler slag is a molten ash collected at the
base of slag tap and cyclone boilers that
is quenched with water and shatters into
black, angular particles having a smooth
glassy appearance.
■ Bottom ash consists of agglomerated ash
particles formed in pulverized coal boilers
that are too large to be carried in the flue
gases. Consequently, they impinge on the
boiler walls or fall through open grates to
an ash hopper at the bottom of the boiler.
Bottom ash is typically gray to black in
color, is quite angular, and has a porous
surface structure.
78
■ Fluidized bed combustion (FBC) materials
consist of unburned coal, ash, and spent bed
material used for sulfur control. The spent
FBC material (removed as bottom ash) contains
reaction products from the absorption
of gaseous sulfur oxides (SO2
and SO3
).
■ Flue gas desulfurization (FGD) materials
are derived from a variety of processes
used to control sulfur emissions from boiler
stacks. These FGD systems include wet
scrubbers, spray dry scrubbers, sorbent injectors,
and a combined sulfur oxide (SOx
and nitrogen oxide (NOx
)
) process. Sorbents
include lime, limestone, sodium-based
compounds, and high-calcium coal fly ash.
■ Fly ash is the coal ash that exits a combustion
chamber in the flue gas and is captured
by air pollution control equipment such as
electrostatic precipitators, baghouses, and
wet scrubbers.
Charah's Decision to Develop a
CCB Landfill
In the fall of 2007, CPSGI voluntarily began
hauling and placing its nonbeneficially reused
CCBs at privately owned lined landfills
in Virginia and western Maryland as part of
a consent decree signed with the Maryland
Department of the Environment (MDE).
At that time, CPSGI's evaluation of alternative
disposal locations to manage its CCBs
in a manner that ensured the health, safety,
and welfare of the community intensified. In
addition, CPSGI was determined to secure a
disposal site for its sole use, as a monofill for
CCBs. To facilitate this evaluation, CPSGI
turned to Charah Inc., a Louisville, Ky.-
based leading ash management provider for
the coal-fired electric utility industry. Charah
was initially tasked with evaluating longterm,
cost-effective CCB disposal opportunities,
including beneficial mine reclamation,
www.powermag.com
industrial waste landfills, and additional
beneficial reuse applications. In 2008, more
than 300 sites in four states were evaluated
for environmental, regulatory, capacity, and
operational feasibility.
By late 2008, Charah presented CPSGI
with a recommendation to purchase and develop
an existing, unused 65-acre industrial
waste landfill, located in Baltimore City, just
miles away from the plants. The site identified
by Charah was already permitted as an
industrial waste landfill and was located within
a heavy industrial zoning district separated
from any residential land use. In addition, no
private wells were located within the vicinity
of the site. The site conformed to CPSGI's
strict environmental requirements and provided
for long-term and cost-effective CCB
disposal. The site would also reduce CPSGI's
carbon footprint by decreasing CCB disposal
hauling distances and travel times.
CPSGI accepted Charah's site recommendation
and shortly thereafter secured an
option to purchase the property. Having successfully
completed the site selection process,
and having met the day-to-day needs of CPSGI,
Charah was then tasked with providing
the design and engineering for converting the
industrial waste landfill into a newly permitted
landfill for disposal of CCB materials.
Permitting Process
While CPSGI and Charah were evaluating
alternative disposal locations for CPSGI's
CCBs, the MDE began reforming its regulatory
program and issued a 68-page report
detailing proposed action on regulations associated
with CCBs. The purpose of this action
was to establish requirements pertaining
to the generation, storage, handling, processing,
disposal, recycling, beneficial use, or
other uses of CCBs.
POWER | October 2011
http://www.powermag.com
POWER October 2011

Table of Contents for the Digital Edition of POWER October 2011
