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• U.S. Environmental Protection Agency	21-P-0175
§ mmj \ Office of Inspector General	July 8 2021
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At a Glance
Why We Did This Audit
We conducted this audit to
determine whether the
U.S. Environmental Protection
Agency and state and local
agencies provide sufficient
oversight to assure that
synthetic-minor sources of air
emissions comply with the
limits in their air permits.
Synthetic-minor sources are
facilities that agree to
restrictions in their permits to
reduce their actual emissions
below major-source thresholds
to avoid being major sources of
air pollution under Clean Air Act
permitting programs. Major
sources are the largest emitters
of air pollution and are subject
to stringent permitting and
compliance requirements.
This audit addresses the
following:
•	Improving air quality.
This audit addresses a top
EPA management challenge:
•	Overseeing states
implementing EPA programs.
EPA Should Conduct More Oversight of Synthetic-
Minor-Source Permitting to Assure Permits Adhere to
EPA Guidance
What We Found
While the EPA oversees state and local	Without clear and
compliance monitoring for synthetic-minor-source	enforceable limitations in
permits, the EPA conducts only limited oversight	synthetic-minor-source
of the permits themselves. The EPA has issued	permits, facilities may
guidance to state and local agencies to develop	emit excess pollution that
enforceable permit limitations in synthetic-minor-	would otherwise subject
source permits, but the Agency does not review	. the more stringent
.. r. ,, 0 .	....	requirements of the Clean
permits to assure the agencies meet this	^ Act major.source
guidance.	permitting programs.
We reviewed 16 natural gas extraction industry synthetic-minor-source permits
from Colorado and Oklahoma and found that many of the permit limitations did
not adhere to the EPA's guidance. For example, in those permits, we found that
102 of 529 permit limits did not have sufficient information within the permit or the
permit's supporting documentation to determine whether the limits were
technically accurate. We also found that 26 limits did not specify the method for
assessing compliance. In addition, 55 limits did not have sufficient monitoring
requirements to determine whether the facility's assumed pollution reduction from
pollution control devices was being achieved. This could result in a synthetic-
minor facility emitting pollutants at or above major-source levels without being
detected.
In addition, we found that the EPA had not communicated several key
expectations for synthetic-minor-source permitting to state and local agencies via
guidance. Further, Oklahoma does not allow the public to participate in its
permitting process for certain synthetic-minor-source permits, as required by
EPA regulations. EPA staff said this may be the case in other states as well.
Recommendations and Planned Agency Corrective Actions
Address inquiries to our public
affairs office at (202) 566-2391 or
OIG WEBCOMMENTS@epa.gov.
We recommend that the EPA (1) develop and implement an oversight plan for
synthetic-minor-source permitting; (2) update its practical enforceability guidance;
(3)	assess EPA studies and other relevant information on enclosed combustion
devices during its next review of applicable regulations to determine whether
revisions to monitoring, record-keeping, and reporting requirements are needed;
(4)	develop and issue new guidance that includes key EPA expectations for
synthetic-minor-source permitting; and (5) take steps to assure that all states
adhere to public participation requirements for synthetic-minor permits. All
recommendations are resolved with corrective actions pending.
List of OIG reports.

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