oEPA
United States	office of Water
Environmental Protection	epa 8I6-U-I6-001
Agency	September 2016
Frequently Asked Questions: Class VI and Subpart RR Reporting
Underground Injection Control (UIC) Class VI Guidance Questions:
What is the purpose of the "Geologic Sequestration of Carbon Dioxide: Underground Injection Control (UIC) Program
Class VI Reporting, Recordkeeping and Data Management Guidance"?
•	This guidance will assist permit applicants and owners or operators in submitting and managing the large
volumes of information associated with Class VI geologic sequestration projects. The guidance identifies
common file formats used for geologic data and technical reports. It also describes how Class VI permit
applicants and owners or operators can use the Agency's electronic Geologic Sequestration Data Tool to meet
the Class VI electronic reporting requirements (at 40 CFR 146.91) throughout the duration of a Class VI project.
Why is EPA developing this and other Class VI guidance documents?
•	In December 2010, the EPA finalized UIC requirements for wells injecting carbon dioxide for geologic
sequestration, creating a new well class, Class VI. In the final Class VI GS Rule, EPA committed to develop a series
of technical guidance documents to help implement the rule.
•	The UIC Program initiated the development of a series of twelve documents addressing all aspects of Class VI
geologic sequestration. The Geologic Sequestration of Carbon Dioxide: Underground Injection Control (UIC)
Program Class VI Reporting, Recordkeeping and Data Management Guidance fulfills our commitment to provide
clarity and guidance regarding the Class VI reporting and recordkeeping requirements.
To whom does this guidance apply?
•	This guidance applies to Class VI owners or operators and cites requirements under 40 CFR Part 144 and 146.
•	This guidance does not apply to operators of other UIC Well Classes -such as Class II wells.
What other resources are available to assist me with a Class VI Project?
•	Guidance documents and technical references addressing many aspects of a Class VI project are available at:
https://www.epa.gov/uic/class-vi-guidance-documents.
Class VI and Subpart RR Questions:
What is the relationship between the UIC Program's Class VI Rule and the Greenhouse Gas Reporting Requirements
under Subpart RR?
• In 2010, the EPA finalized an effective and coherent regulatory framework to ensure the long-term, secure and
safe storage of large volumes of carbon dioxide. The regulatory requirements and safeguards of the UIC Program
and complementary monitoring and reporting requirements of the Greenhouse Gas Reporting Program,
together ensure that sequestered carbon dioxide will remain secure and provide the monitoring to identify and
address potential leakage using Safe Drinking Water Act and Clean Air Act authorities.

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The UIC Class VI requirements are focused on ensuring protection of underground sources of drinking water
where carbon dioxide is injected through an injection well for geologic sequestration (long term storage of
carbon dioxide). The requirements focus on the siting, permitting, operation, testing and monitoring, post-
injection site care and site closure of a Class VI well or wells.
Reporting under subpart RR is required for facilities that have received a UIC Class VI permit. Subpart RR
facilities are required to report basic information on the mass of carbon dioxide received for injection; develop
and implement an EPA-approved monitoring, reporting, and verification (MRV) plan; report the mass of carbon
dioxide sequestered using a mass balance approach; and report annual monitoring activities.
Information gathered or developed and submitted for compliance with UIC Class VI technical requirements
could also be used to meet subpart RR requirements. For example, a subpart RR MRV plan could draw on the
site characterization and computational modeling data required for UIC Class VI permitting.

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