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          Texas Natural Resource Conservation Commission

                      INTEROFFICE MEMORANDUM

NSRP Chemical Section

March 25, 1999

Tammy Villarreal

Kurt Kind

Integration of 40 CFR 63.11 Flare Requirements with Flare BACT
Requirements (40 CFR 60.18)

40 CFR 63.11 provides flare control requirements for sources covered by MACT standards
(National Emission Standards for Hazardous Air Pollutants for Source Categories). A
permitted flare may be subject to these requirements, in addition to the operating and
testing requirements of 40 CFR 60.18 (NSPS) referenced to ensure BACT in a permit

Although these two federal regulations are organized differently, the technical
requirements for flare operation may be considered equivalent. EPA regulation
background documents also confirm that both sets of regulations are meant to provide at
least 98 percent destruction efficiency and are derived from the same flare testing results.
Therefore, the regulations are considered technically equivalent and provide for a flare
that satisfies BACT.

Given that the two federal regulations are technically equivalent, any flare testing to be
performed for permit purposes may be done in accordance with 40 CFR 63.11 rather than
40 CFR 60.18, if flare testing is required by 40 CFR 63.11. The option to test per 40 CFR
63.11 must be stated in the permit conditions. This does not allow the permit holder to
substitute for any flare testing that is required by any federal regulations.

Flare permit conditions should still reference 40 CFR 60.18 when specifying the flare
operating conditions to provide for consistent permit language and enforceability.  An
example using condition language from the sample conditions in the Flares and Vapor
Oxidizers guidance document is provided below (added language is underlined):

  1.    Flares shall be designed and operated in accordance with the following
   A.   The combined assist natural gas and waste stream to the flare shall meet the
          40 CFR 60.18 specifications of minimum heating value and maximum tip velocity
          under normal, upset, and maintenance flow conditions.  Compliance with this
          condition shall be demonstrated by monitoring required section D below.  Flare
          testing per 40 CFR 60.18(f) may be requested by the TNRCC regional office to
          demonstrate compliance with this condition.  Flare testing per 40 CFR 63.11(b)
          may be substituted to satisfy this permit requirement if flare testing per 40 CFR
          63.11 is required any federal regulation.
   b.   The flare shall be operated with a flame present at all times and have a constant
          pilot flame... (there is no change in the rest of the condition)