4 The record articles

A Preponderance of Evidence

Posted: February 29th, 2012

Author: All4 Staff 

In 2008, the United States Court of Appeals for the District of Columbia Circuit (D.C. Circuit Court) vacated portions of CAA section 112 regulations (i.e., 40 CFR 63.6(f)(1) and (h)(1)) that governed emissions of hazardous air pollutants (HAP) during periods of startup, shutdown, and malfunction (SSM) (see Sierra Club v. EPA, 2008).  Prior to the vacatur, affected sources were exempt from the requirement to comply with the otherwise applicable emission standard during SSM events, provided that they operated in accordance with their SSM Plan.  Under Sierra Club v. EPA, the court established that MACT standards apply at all times.  Admitting that malfunctions do actually occur at manufacturing facilities, U.S. EPA has been adding an “affirmative defense” provision in MACT standards to address emissions that occur during periods of malfunctions. The affirmative defense provision is applied “after the fact,” that is, it is applied “in the context of an enforcement proceeding,” a key point.  This change represents a significant difference from previous “protection” under the SSM provisions.  Under SSM, sources were, in general, innocent until proven guilty.  With the vacatur of SSM provisions, excess emissions at any time are violations.  A valid affirmative defense only provides mitigating circumstances for consideration in a judicial or administrative proceeding.  To be valid, facilities must prove by a “preponderance of evidence” that the malfunction-related excess emissions meet stringent criteria that are defined in the rule.   As such, routine facility operating records have been elevated, in essence, to legal document status.  For exceedances caused by malfunctions, regulatory authorities will determine an appropriate response (during an enforcement proceeding) based on:

  • Good faith efforts to minimize emissions during malfunction periods
  • Preventative and corrective actions
  • Results of a root cause analysis to ascertain and rectify excess emissions
  • Whether the source’s failure to comply was really as a result of a “malfunction”

As new MACT standards are promulgated and existing standards are revised, more and more source categories will be affected by this regulatory shift.  ALL4 recommends that affected facilities evaluate current facility operating and related records (e.g., employee training) and implement plans to ensure that an affirmative defense can be developed in response to excess emissions during malfunction periods.


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