Class VI

A well that is used for injecting a carbon dioxide stream for geologic sequestration that:

• Is not experimental in nature and injects a carbon dioxide stream for geologic sequestration, beneath the lowermost formation containing an underground source of drinking water;
• Has granted a waiver for the injection depth requirements pursuant to requirements of Water Quality Rules Chapter 24, Section 15; or
• Has received an expansion to the areal extent of an existing Class II enhanced oil recovery or enhanced gas recovery aquifer exemption pursuant to Water Quality Rules, Chapter 24, Section 16.

Wyoming Environmental Quality Act and Industrial Development Information and Siting Act (2020 Edition) 35-11-103:

• (xx) "Geologic sequestration" means the injection of carbon dioxide and associated constituents into subsurface geologic formations intended to prevent its release into the atmosphere;
• (xxi) "Geologic sequestration site" means the underground geologic formations where the carbon dioxide is intended to be stored;
• (xxii) "Geologic sequestration facilities" means the surface equipment used for transport, storage and injection of carbon dioxide.

Carbon sequestration permit requirements and Unitization are outlined in 35-11-313 through 35-11-317

Water Quality Rules Chapter 24, Section 2(v) “Geologic sequestration project” means an injection well or wells used to emplace a carbon dioxide stream into an injection zone for geologic sequestration.  It includes the subsurface three-dimensional extent of the carbon dioxide plume, associated pressure front, and displaced fluid, as well as the surface area above that delineated region.

The Wyoming Department of Environmental Quality implements the Underground Injection Control Class VI Program.  Water Quality Rules, Chapter 24 outlines the permitting requirements for Class VI wells. 

The following is the permitting, operating and closure process for a Class VI well in Wyoming:

For more information on how to apply for a Class VI permit, please review the Class VI Injection Wells and Facilities Underground Injection Control Program Informational Program Packet located in the ‘Forms and Guidance’ tab above.

Forms are also available for:

• Informational Meeting
• Site Characterization
• Pre-application Meeting
• Permit Application Part 1
• Permit Application Part 2 (a Word Version is available upon request)
• Depth Waiver Form
• Expansion of the Areal Extent of a Class II Aquifer Exemption

Questions regarding Class VI wells and the permitting process, or to request a Word version of the Permit Application Part 2, please contact Lily R. Barkau, P.G. at (307) 777-7072 or lily.barkau@wyo.gov

Section 1421 of the Safe Drinking Water Act (SDWA) requires the US EPA to develop UIC program requirements that protect underground sources of drinking water.  Primary enforcement authority, often called primacy, refers to state, territory, or tribal responsibilities associated with implementing US EPA approved UIC programs.  Primacy programs are established under Section 1422 and 1425 of the SDWA. Wyoming received primacy over Class I through V in 1983.  The Wyoming Department of Environmental Quality received primacy over Class VI wells on September 3, 2020.  Wyoming is one of two states to have received primacy for implementing the Class VI program; the other is North Dakota.

Wyoming’s primacy documents can be found here:

https://www.federalregister.gov/documents/2020/10/09/2020-20544/wyoming-underground-injection-control-program-class-vi-primacy