Frequent Questions

Are toxic chemicals in ash manufactured during combustion eligible for the de minimis exemption?

A covered facility combusts coal in a combustion unit. The coal contains a non-PBT chemical below de minimis amounts. During combustion, chemicals are manufactured. The ash containing the toxic chemicals is generated from the combustion of the coal. The ash is then sold to another facility for direct reuse in the manufacture of concrete blocks. If the toxic chemicals in the ash are below the appropriate de minimis concentration, are they eligible for the de minimis exemption?

The toxic chemical in the coal being combusted should be considered towards the facility’s otherwise use threshold and this activity is eligible for the de minimis exemption. The toxic chemicals that are manufactured as a result of the combustion process are byproducts and therefore not eligible for the de minimis exemption. The chemicals in the ash that is sold for direct reuse off-site are considered processed. After combustion, when the facility is preparing the toxic chemicals in ash for distribution in commerce, the non- PBT chemicals are eligible for the de minimis exemption. Additional guidance regarding the de minimis exemption can be found in Directive #2 of the Addendum to 1998 Question and Answer Document and the Revised 1998 EPCRA Section 313 Questions and Answers Document.

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