Date: August 3, 2016
Source: US EPA
A federal appeals court, siding with environmental groups, tossed out part of a contentious air pollution rule for boilers for an improper exemption within the regulation. In its 162-page opinion, the Court of Appeals for the District of Columbia Circuit rejected arguments from industry that the EPA's maximum achievable control technology, or MACT, standards for industrial, commercial and institutional boilers is too strict. A key piece of the decision found that the EPA was wrong to leave certain boiler units with low levels of emissions out of the subcategories it constructed for the rule. The Clean Air Act, the judges wrote, "demands that source subcategories take the bitter with the sweet," and requires "without ambiguity" that all relevant units be kept in a subcategory.
Under the rule, the EPA created subcategories based mainly on the type of fuel the boiler burned. To qualify for a particular subcategory, the source only has to burn 10% of the subcategory-defining fuel. Yet when determining average emissions from the best-performing sources by fuel type, the EPA declined to consider emissions from boilers that burned less than 90% of the subcategory-defining fuel. The court said doing so excluded some of the best-performing facilities from being considered when the EPA determines each subcategory's MACT "floor." The court vacated that part of the rule, while remanding five other parts of the boiler and incinerator MACT standards to the EPA for review without vacatur.