Credible Evidence Revisions

In an October 22, 1993 Federal Register, EPA solicited public comment on a proposal to amend 40 CFR Parts 51, 52, 60 and 61 to eliminate language that has been read to provide for exclusive reliance on reference test methods as the means of demonstrating compliance with various emission limits under the Clean Air Act (``CAA'' or ``Act''). These revisions--generally referred to as the ``credible evidence'' revisions--were designed to clarify that non-reference test data can be used in enforcement actions, and to remove any potential ambiguity regarding this data's use for compliance certifications under Section 114 and Title V of the Act. In the same document, EPA proposed an ``enhanced monitoring'' rule under Section 114 and Title V. EPA subsequently decided to suspend development of the original enhanced monitoring rule and develop a compliance assurance monitoring (``CAM'') approach to serve the same statutory goals as the original enhanced monitoring proposal. Today's rulemaking finalizes the previously proposed credible evidence revisions to Parts 51, 52, 60 and 61. EPA will take final action regarding enhanced monitoring and CAM in a separate rulemaking.