Harmonization of Part 60 and Part 75

1

• Harmonization of Part 60 and Part 75
• CEM Requirements
• Robert Vollaro
• U.S. EPA
• Clean Air Markets Division

2
Background

• On February 28, 2005, EPA proposed amendments to
  the SO2 , NOx, and PM emission limits in three
  NSPS boiler regulations---Subparts Da, Db and Dc.
• As part of that rule package, the Agency also
  proposed revisions to
• Certain CEM provisions in Subparts D, Da, Db, and
  Dc
• 60.13(h) of the NSPS General Provisions and
• Appendices B and F of Part 60.
• The purpose of these additional rule changes was
  to harmonize, to the extent possible, the CEM
  provisions of Parts 60 and 75, for sources
  subject to both sets of regulations.

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Background (contd)

• The proposed revisions would
• Make the method of calculating hourly emissions
  averages from CEMS data consistent between Parts
  60 and 75
• Allow Part 75 span values to be used for Part 60
  monitoring applications
• Allow the 7-day calibration drift test in Part 60
  to be done on 7 consecutive unit operating days,
  rather than 7 consecutive calendar days
• Allow the CEMS Quality Assurance provisions of
  Part 75, Appendix B to be substituted for the
  procedures in Part 60, Appendix F, for sources
  subject to both sets of QA requirements

4
Background (contd)

• Comments received on the proposed CEMS rule
  changes were generally supportive.
• However, a number of adverse comments were
  received on the proposed revisions to the Subpart
  Da, Db and Dc emission limits.
• Issues regarding the impact of the emission
  limits were also raised by the Office of
  Management and Budget (OMB) and the Department of
  Energy (DOE).
• But EPA was under a court-ordered deadline to
  finalize the Subpart Da, Db, and Dc emission
  limits by February 9, 2006.
• Therefore, to meet the deadline, the Agencys
  legal and technical staff focused exclusively on
  resolving the controversy over the Subpart Da,
  Db, and Dc emission limits

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Background (contd)

• Consequently, there was insufficient time to
  properly review the CEMS amendments, and they
  were not included in the final rule that appeared
  in the Federal Register on February 27, 2006.
• EPA subsequently received petitions to reconsider
  the Subpart Da, Db, and Dc emission limits
• On February 9, 2007, EPA published a proposed
  response to the petitions to reconsider (72 FR
  6320).
• In that Federal Register notice, the Agency
  stated its intention to finalize the Part 60 vs.
  75 CEM harmonization amendments along with the
  final Subpart Da, Db, and Dc emission limits
• Under a court order, the final rule was signed by
  the EPA Administrator on April 13, 2007.
• As of May 7, 2007, the final rule has not yet
  been published in the Federal Register.

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What Changes Have Been Made to the Part 60 CEM
Requirements ?

• Based on comments received and internal
  discussion and deliberation within the Agency
  during the rulemaking process, the final CEM rule
  revisions will differ somewhat from the proposal.
  
• Despite this, EPA believes that the revisions go
  a long way toward accomplishing the intended
  purpose, which is to simplify and reduce the cost
  of compliance for sources under both Parts 60 and
  75.
• The revisions to 60.13(h), concerning the
  validation of CEM hourly averages, were finalized
  with only minor edits.
• The revision to PS 2, allowing the 7-day drift
  test to be done on 7 consecutive unit operating
  days was finalized

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What Changes Have Been Made to the Part 60 CEM
Requirements ? (contd)

• Revisions to Subparts D, Da, and Db, allowing the
  site-specific Part 75 SO2 and NOx span values to
  be used in lieu of the more prescriptive Part 60
  span values, were finalized
• The proposed revisions to Part 60, Appendix F
  were withdrawn. Instead, Subparts Da and Db were
  revised to allow
• Data from certified Part 75 monitors (SO2, NOx,
  CO2, O2, and flow rate) to be used to demonstrate
  compliance with the Part 60 emission limits
• The QA/QC procedures in Part 75, Appendix B to be
  followed instead of the procedures in Part 60,
  Appendix F

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What Changes Have Been Made to the Part 60 CEM
Requirements ? (contd)

• However, the use of Part 75 CEM data and QA/QC
  procedures for Subpart Da and Db compliance is
  not unconditional
• Part 75 bias-adjusted data and substitute data
  are not to be used for Part 60 compliance
  determinations
• For units subject to a lb/mmBtu SO2 standard, the
  RATA of the SO2 CEMS must be done on a lb/mmBtu
  basis and meet the RA specification in PS 2, in
  addition to meeting the Part 75 RA specification
  on a ppm basis
• If the span value of an SO2 or NOx monitor is lt
  100 ppm, the calibration drift and out-of-control
  provisions in section 4.3 of Appendix F must be
  followed for Part 60 data validation
• If the span value of an SO2 or NOx monitor is
  30 ppm, cylinder gas audits (CGAs) must be
  performed according to section 5.1.2 of Appendix
  F

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What Changes Have Been Made to the Part 60 CEM
Requirements ? (contd)

• For the RATA of a NOxdiluent CEMS, if the
  average NOx emission rate measured by the
  reference method is lt 0.100 lb/mmBtu, the RA
  specification in PS 2 must be met in addition to
  the Part 75 RA specification
• The last three conditions above pertain to
  low-emitting sources. The reason for these
  conditions is that there are a few cut points
  at which the Part 60, Appendix F specifications
  actually become more stringent than those in Part
  75, Appendix B
• For SO2 and NOx span values lt 100 ppm, the
  highest single-day calibration error allowed by
  Appendix F (i.e., 10 of span) is more stringent
  than Part 75
• For SO2 and NOx span values 30 ppm, Part 75
  does not require linearity checks, but Appendix F
  requires CGAs
• For NOx emission rates lt 0.100 lb/mmBtu, the
  relative accuracy specification in PS 2 becomes
  more stringent than the alternative Part 75 RA
  specification (0.020 lb/mmBtu mean difference)

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What Changes Have Been Made to the Part 60 CEM
Requirements ? (contd)

• Two commenters on the harmonization amendments
  asked EPA to consider making revisions beyond
  those that were proposed. Most of the requested
  revisions were considered to be too controversial
  and were not incorporated. However, the
  following additional revisions were made based on
  comments received
• The requirement for the unit to be operating at gt
  50 of normal load during the 7-day drift test
  has been removed. The unit needs only to be
  on-line during the measurements.
• Sections 5.1.1 and 5.1.4 of Appendix F have been
  revised. In a non-operating quarter (i.e., zero
  hours of unit operation)
• CGAs are not required and
• If a RATA is due, its deadline is automatically
  extended to the end of the next operating quarter.

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Next Steps

• The amendments to Part 60 that were signed on
  April 13, 2007 represent a significant step
  forward. However, the Part 60 and Part 75 CEM
  provisions can (and, we believe, should) be
  further harmonized.
• CAMD will look for opportunities to work with
  OAQPS to bring about the necessary rule
  revisions.
• Some recommended items for discussion
• The adequacy of the CEM performance
  specifications in both Parts 60 and 75 for very
  low-emitting sources
• Possibly adding more flexibility (e.g., grace
  periods, the QA operating quarter concept,
  etc.) to Appendix F

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Next Steps (contd)

• Inconsistent opacity monitoring requirements
• Possibly allowing a wider application of Part 75
  QA/QC procedures to other sources that are
  subject to Appendix F, either by permit or
  regulation
• Possibly extending the procedural aspects of the
  Part 75 QA/QC (i.e., the types of tests
  performed, test frequency, etc.) to other CEMS
  that are not subject to Part 75 (e.g., CO
  monitors).