EPA's November 30, 2016 final rule changed how oil-and-gas equipment leaks could be detected and reported under subpart W of the Greenhouse Gas Reporting Program. Detection identifies leaking equipment. Emission factors then help calculate the emissions attributed to those leaks. These are related steps, but they are not interchangeable measurements or a repair requirement. [2016-27981]

The final rule permitted Method 21 using a 500 parts-per-million-by-volume leak definition as an alternative to the specified optical gas imaging method. EPA supplied separate leaker factors appropriate to that alternative. The 500 ppmv figure describes the method's leak definition, not a universal safety threshold. Choosing a detection method did not authorize a reporter to mix calculation factors without regard to that choice. [2016-27981]

The January 29 proposal had already paired additional monitoring methods with emission factors and nine new or substantially revised data elements. It linked the design to then-proposed new-source performance standards; the November rule referred to finalized standards. The proposal supplies the earlier design stage, while the final establishes the adopted decisions. Neither document independently verifies emissions reductions. [2016-01669][2016-27981]

The timing also had separate parts. Effectiveness was January 1, 2017; the revised methods applied for reporting year 2017, with first annual reports due April 2, 2018. Subpart W did not itself require leak repairs, but that did not remove obligations under other rules. Reporting an emissions estimate, meeting a deadline and fixing equipment remained distinct questions. [2016-27981]

Source documents

  1. Greenhouse Gas Reporting Rule: Leak Detection Methodology Revisions and Confidentiality Determinations for Petroleum and Natural Gas Systemshttps://www.govinfo.gov/content/pkg/FR-2016-11-30/html/2016-27981.htm
  2. Greenhouse Gas Reporting Rule: Leak Detection Methodology Revisions and Confidentiality Determinations for Petroleum and Natural Gas Systemshttps://www.govinfo.gov/content/pkg/FR-2016-01-29/html/2016-01669.htm