DEFINITION OF BACT AND TBACT

District Regulation 2, Rule 2, Section 206 defines Best Available Control Technology as follows:

2-2-206 Best Available Control Technology (BACT): For any source or modified source, except cargo carriers, the more stringent of:

206.1 The most effective emission control device or technique which has been successfully utilized for the type of equipment comprising such a source; or

206.2 The most stringent emission limitation achieved by an emission control device or technique for the type of equipment comprising such a source; or

206.3 Any emission control device or technique determined to be technologically feasible and cost-effective by the APCO; or

206.4 The most effective emission control limitation for the type of equipment comprising such a source which the EPA states, prior to or during the public comment period, is contained in an approved implementation plan of any state, unless the applicant demonstrates to the satisfaction of the APCO that such limitations are not achievable. Under no circumstances shall the emission control required be less stringent than the emission control required by any applicable provision of federal, state or District laws, rules or regulations.

The APCO shall periodically publish and update a BACT Workbook specifying the requirements for commonly permitted sources. BACT will be determined for a source by using the workbook as a guidance document or, on a case-by-case basis, using the most stringent definition of this Section 2-2-206.

The proposed District Regulation 2, Rule 5, Section 201 defines Best Available Control Technology for Toxics as follows:

2-5-202 Best Available Control Technology for Toxics (TBACT): For any new or modified source, except cargo carriers, the most stringent of:

202.1 The most effective emission control device or technique which has been successfully utilized for the type of equipment comprising such a source; or

202.2 The most stringent emission limitation achieved by an emission control device or technique for the type of equipment comprising such a source; or

202.3 As a minimum, TBACT shall include the most stringent emission control for a source type or category for which a Maximum Achievable Control Technology (MACT) standard has been proposed, or for which the CARB has developed an Air Toxic Control Measures (ATCM). Under no circumstances shall the emission control required be less stringent than the emission control required by any applicable provision of federal, state or District laws, rules, regulations or requirements.

Clearly the recurring theme in the above definitions of BACT and TBACT is "the most effective emission control" or "the most stringent emission limitation." In most cases, TBACT is the same as BACT in actual application. Most sources which meet TBACT will be in compliance with the relevant federal MACT standards when these standards are established with respect to the level of control required. However, TBACT may not necessarily include the compliance and enforcement measures (such as monitoring, test methods, recordkeeping, reporting, and compliance certification) of a MACT standard, which may be substantially different.