US EPA recently denied a petition to revise the definition of a corrosive hazardous waste in the RCRA regulations.The petition sought to “lower” the threshold for a corrosive hazardous waste from a pH of 12.5 to a pH of 11.5. It also sought to expand the definition of corrosive to cover non-aqueous wastes.
The changes requested would have brought more substances under regulation as corrosive hazardous wastes (i.e., D002). Ammonia, for example, has a pH of about 11.6 and would have been subject to the full scope of the RCRA hazardous waste regulations when discarded if EPA had approved this petition.
EPA “tentatively” denied this petition in April 2016
and has now “officially” denied it. The decision is effective June 15, 2021.
In 2015, Lion News reported on a lawsuit lodged by the Public Employees for Environmental Responsibility (PEER)
that sought to persuade EPA to change the definition of a corrosive hazardous waste.
Under RCRA, a hazardous waste is corrosive if it is:
- Aqueous and has a pH less than or equal to 2 or greater than or equal to 12.5; or
- A liquid and corrodes steel at rate greater than 6.35 mm (approx 1/4 inch) per year at a test temperature of 55 degrees Celsius (40 CFR 261.22).
Why Are Corrosive Liquids Hazardous Wastes?
In 1976, the Resource Conservation and Recovery Act (RCRA) amended existing law to create a cradle-to-grave management system for hazardous waste. The law ordered US EPA to identify wastes that should be regulated as hazardous.
In 1980, EPA proposed regulations to make corrosiveness
a hazardous waste characteristic. Defined as “the property that makes a substance capable of dissolving material with which it comes in contact,” corrosiveness (or corrosivity) can endanger human health and the environment in various ways.
A corrosive waste can damage human skin and cause injury or destroy the container it’s in and cause a release to the environment. A corrosive waste also can react with other wastes
during disposal and create new hazardous substances, dangerous amounts of heat, toxic fumes, fire, or explosion.
What About Corrosive Solids?
The denied petition also sought to expand the definition of corrosive to include non-aqueous waste (i.e., solids). EPA claims that liquid wastes constitute a far greater percentage of hazardous wastes and have a more immediate potential to damage the environment.
In addition, corrosive solids
are less likely than liquid wastes to cause problems because the ability of a solid to form an aqueous solution of high or low pH varies with its physical and chemical characteristics and the management conditions.
As a result, the EPA concluded that there is no demonstrated need to address solids which may become corrosive in the definition of corrosivity.
History of the Corrosive Characteristic
In its original proposed regulations (1980),
EPA defined aqueous wastes with pH levels below 3 or above 12 as hazardous wastes.
Stakeholders who commented on the proposal pointed out to EPA that an upper limit of pH 12.0 could include waste lime and many lime-treated wastes and sludges with beneficial uses, including in agriculture.
Stakeholders also told EPA that a lower limit of pH 3.0 would include common substances like cola drinks and many industrial wastewaters (prior to neutralization).
After considering those public comments, EPA changed the range of acceptable pH levels under the corrosivity characteristic, creating the corrosivity criteria we use today.
EPA’s denial of the petition to change the definition of a corrosive hazardous waste means that criteria will remain the same, at least for now.
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