Three Solutions for Legacy Coal Ash Disposition
When coal combustion residuals (CCR), such as coal ash, fly
ash, bottom ash, gypsum and other solids produced by coal-fired power plants are
improperly stored, they can contaminate surrounding soil and ground and surface
water, causing a host of environmental problems.
The most expedient way to deal with legacy CCR stored in
outdoor ponds has been “cap in place,” which involves covering it where it lies.
This is deemed “safe under certain conditions” by EPA regulations, but environmentalists
and the public have become more savvy to the inherent drawbacks and consider
cap in place a non-solution.
No one intentionally wants to harm the environment, so utilities
that have legacy CCR, environmentalists, legislators and energy end users do share
common goals for its proper disposition. Foremost is the desire to recycle as
much as possible to keep the coal ash out of landfills, but the simple fact is
that the quantity of legacy CCR far outstrips current capacity and requires
innovation to solve it.
For instance, in Virginia, legacy coal ash is estimated to be 30 million tons or 27 million cubic yards. Indiana is wrestling with what to do with 60 million cubic yards. These are examples of only two states dealing with legacy CCR.
is a simplified process for beneficiation or recycling and the federal CCR rule
defines this as “a beneficial use of CCR that binds the CCR into a solid matrix
that minimizes its mobilization into the surrounding environment.” So, CCR is repurposed
to create building/construction products such as brick or aggregate, and as Portland
cement (PC) substitute in concrete.
We support CCR microencapsulation as the preferred method of
CCR recycling, but it currently faces production and market limitations. For
utilities, it’s a race to get processing plants online to prepare coal ash for
recycling by end-product manufacturers who have finite production capacity and accept
CCR on a first-come, first-served basis.
is another, often simpler, solution for beneficial use that deals with the
remaining legacy coal ash. For years, using CCR, rather than earth, as fill
material to construct embankments for landfills, highways, dikes and levees has
proven itself a virtually foolproof and comprehensive beneficial use.
Coal ash is transferred and encapsulated into berms or bunkers
designed with the land’s eventual reuse in mind. They’re lined with the same geosynthetic
material used in modern landfills that blocks seepage into surrounding earth
and groundwater. As these structures are completed, they’re fully entombed in liner.
This method is an accepted reuse by engineering firms and utilities which has
been used for land redevelopment, solar farming or any project that beneficially
reuses materials that would otherwise be disposed of; offsetting the use of
other natural resources.
Macroencapsulation, in most cases, is a large-volume beneficial
use. It’s the most practical solution for constructing berms or bunkers near
the coal ash source because roadway logistics, transportation costs and risks
are all minimized. In addition, no time is spent, as with microencapsulation, in
locating and negotiating terms with end-product manufacturers, building processing
plants or guessing what the construction market will do. Once the initial macroencapsulated
bunker is lined, coal ash removal can begin, efficiently and immediately.
environmentally, the last resort – has historically been the first choice of
utilities across the U.S. after cap in place efforts have been exhausted because
disposal is relatively easy. However, it’s the last resort because the number
of U.S. landfills is dwindling and they tend to be in remote locations.
Additionally, current projections for landfills’ remaining
“air space” (waste capacity) don’t include coal ash. So, to begin adding coal
ash to an existing landfill’s waste stream maxes out that landfill’s capacity
years sooner and creates the need for expansion.
Using landfills also comes with the drawbacks of trucking coal
ash over public roadways, exacerbating congestion and risk of spills, as well as
increased transportation costs to reach landfills in remote rural areas.
Therefore, disposal as a disposition method for legacy CCR
should only be considered after ALL
other methods have been exhausted.
No matter what method is chosen, project costs matter in all
CCR disposition. Next, we’ll discuss the time factors and financial pros and
cons of each solution.