Fly ash grains at magnified view, Image credit:Coal Ash Resource Center
Fly ash produced by coal-fired boilers is commonly used as an agricultural soil amendment/fertilizer in parts of the USA. Although the fly ash may be characterized to ensure toxic constituent levels remain under State agriculture department-established threshold concentrations, that constraint, where it exists, is aimed primarily at minimizing risks posed to crop health and to produce or grain consumers. As long as available nitrogen levels are adequate, and soil moisture sufficient, it is presumed that plant uptake-rates for heavy metals such as arsenic or lead can be kept to acceptable levels. The guidance's for determining application rates are based on a narrow view of environment impact potential, however, and are not uniform by state.
Unmeasured and un-managed risks.
It turns out that radium is a common constituent of fly ash. A common radium isotope decays into, among other things, radon gas. The half-life of radium is more than a thousand years. Think basements put on land where fly ash had been previously disposed. For this reason alone, soil amendments on the periphery of expanding cities is a questionable practice.
Should USEPA determine that fly ash should no longer be exempted from hazardous waste regulations, that it should instead be managed commensurate with the actual metal levels measured in each and every batch of fly ash shipped away from interim storage, managment costs could go up and this practice of soil amending may have to end, or at least be evaluated closely on a site by site basis.
What we didn't know because it wasn't previously measured could hurt us.
Other possible impacts that have been overlooked include: what might be moving into streams via runoff; levels of heavy metals making it into groundwater; and, metal-laced soil particles blown about by the wind.
This practice is occasionally referred to as...can you guess?
Fly Ash Recycling?
Environmental Health News has spilled the "recycling" story for us in, Is recycling coal fly ash at farms environmentally safe?. Here are a few choice excepts.
Tons of fly ash are routinely added to soil to nourish vegetables, peanuts and other crops, primarily in the Midwest and Southeast. But now the spill has raised questions about whether this longstanding agricultural practice is environmentally sound.
As a result of lobbyists keeping the Federal EPA from regulating fly ash disposal:
Some states regulate it but their guidelines vary and often require no monitoring of how it is used, said Jeffrey Stant, director of the Coal Combustion Waste Initiative for the Environmental Integrity Project... For more than a decade, companies have mixed fly ash with other waste to produce soil and compost. About 50,000 tons are used annually for agriculture nationwide.
It might end up used with root crops and leafy vegetables.
Crops grown in quantities of fly ash ranging from 5 to 20 percent of soil weight absorbed toxic metals, according to a study by Indiana State University researchers.
When the amount of fly ash increased, the crops absorbed higher concentrations of arsenic and titanium. Basil and zucchini contained potentially toxic amounts of arsenic exceeding 6 parts per million. Concentrations of greater than 2 ppm had severe effects on vegetables, damaging the plants and decreasing production, wrote the scientists in a 2004 paper published in Environmental Geology.
Best practices review by USEPA to determine effectiveness of existing fly ash soil "amendment" programs.
Congress requires creation of industry (not taxpayer) funded, research program, overseen by a special purpose board appointed by the USEPA Adminstrator, including representation by USDOE, selected state agriculture departments, utility industries, organic farming organizations, Environmental NGO's, etc. Report due to Congress to assist in regulatory needs assessment.
For your further fly ash reading pleasure.
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