Escalating Threats of Contamination
149
such hazards. For example, federal statutes such as the Migratory Bird
Treaty Act and the Endangered Species Act prescribe strict penalties
(monetary fines and/or imprisonment) for killing wildlife by these
means, whether or not the owner/operator knowingly allows this "take"
to occur (eg, Margolin 1979).
The underlying problem with constructed wetlands is the failure of
those who develop wetland selenium treatments to adequately evaluate risks to fish and wildlife. For example, researchers developing treatment methods typically seek to establish how effective wetlands can
be in removing selenium from water, but make little or no effort to
document or acknowledge ecological hazards (eg, Hansen et al. 1998;
Terry and Zayed 1998). Consequently, the methods have inherent dangers that are not readily apparent to potential users, a major shortcoming that is pervasive in the wetland treatment technology field. Many
wetland-treatment methods are being marketed on a national scale in
the United States without full knowledge or disclosure of the risks they
pose to fish and wildlife. Constructing a wetland to treat seleniumladen wastewater may result in selenium poisoning wherever this practice is used.
Disposal of Fly Ash
Treatment technologies to reduce airborne particulate emissions from
coal-fired power plants have reached a high level of efficiency, sometimes achieving in excess of 99.5 % removal. However, this impressive
protection of air quality belies other environmental risks associated
with large-scale burning of coal. Huge volumes of seleniferous fly ash
(50-300 Ilg Se/g) and other combustion wastes are generated in the
process. The current annual production of coal ash in the United States
is about 120 million tons and is projected to steadily increase in the
coming decades (EPA 1998). Most fly ash is disposed in landfills that
are generally built on clay soils (to impede downward movement of
contaminants or upward movement of groundwater), capped with a
layer of clay (to impede infiltration of rainwater) and topsoil, and revegetated. Over time, landfills can become unstable, allowing the surface
clay cap or the underlayment clay to crack, rainwater or groundwater
to infiltrate, and leaching of selenium to occur. Selenium-laden seepage (50-200 Ilg SelL) can then be transported off-site, where it may
ultimately reach streams or other surface water, bioaccumulate, and
threaten the health of fish populations. In fact, the design specifications for fly-ash landfills acknowledge that, even under the best conditions, some contaminated leachate will result (Murtha et al. 1983).
One example of this problem occurred in 1991 in eastern Pennsylvania, where plans were being made to construct a 65 hectare landfill
149
such hazards. For example, federal statutes such as the Migratory Bird
Treaty Act and the Endangered Species Act prescribe strict penalties
(monetary fines and/or imprisonment) for killing wildlife by these
means, whether or not the owner/operator knowingly allows this "take"
to occur (eg, Margolin 1979).
The underlying problem with constructed wetlands is the failure of
those who develop wetland selenium treatments to adequately evaluate risks to fish and wildlife. For example, researchers developing treatment methods typically seek to establish how effective wetlands can
be in removing selenium from water, but make little or no effort to
document or acknowledge ecological hazards (eg, Hansen et al. 1998;
Terry and Zayed 1998). Consequently, the methods have inherent dangers that are not readily apparent to potential users, a major shortcoming that is pervasive in the wetland treatment technology field. Many
wetland-treatment methods are being marketed on a national scale in
the United States without full knowledge or disclosure of the risks they
pose to fish and wildlife. Constructing a wetland to treat seleniumladen wastewater may result in selenium poisoning wherever this practice is used.
Disposal of Fly Ash
Treatment technologies to reduce airborne particulate emissions from
coal-fired power plants have reached a high level of efficiency, sometimes achieving in excess of 99.5 % removal. However, this impressive
protection of air quality belies other environmental risks associated
with large-scale burning of coal. Huge volumes of seleniferous fly ash
(50-300 Ilg Se/g) and other combustion wastes are generated in the
process. The current annual production of coal ash in the United States
is about 120 million tons and is projected to steadily increase in the
coming decades (EPA 1998). Most fly ash is disposed in landfills that
are generally built on clay soils (to impede downward movement of
contaminants or upward movement of groundwater), capped with a
layer of clay (to impede infiltration of rainwater) and topsoil, and revegetated. Over time, landfills can become unstable, allowing the surface
clay cap or the underlayment clay to crack, rainwater or groundwater
to infiltrate, and leaching of selenium to occur. Selenium-laden seepage (50-200 Ilg SelL) can then be transported off-site, where it may
ultimately reach streams or other surface water, bioaccumulate, and
threaten the health of fish populations. In fact, the design specifications for fly-ash landfills acknowledge that, even under the best conditions, some contaminated leachate will result (Murtha et al. 1983).
One example of this problem occurred in 1991 in eastern Pennsylvania, where plans were being made to construct a 65 hectare landfill