Class II Injection Wells

If you are new to FracTracker.org, our coverage of Class II injection is thorough and growing. There are over 150,000 injection wells in the U.S. A break down by state is available from the US EPA.

Class II underground injection wells are a major disposal pathway for liquid oil and gas exploration and production wastes. Much of the solid waste from oil and gas wells will end up in landfills or other types of impoundments, as well as spread on the surface (called land-spreading).

Class II Wastes Include:

• Produced water
• Drilling fluids
• Spent well treatment or stimulation fluids
• Pigging wastes
• Gas plant wastes (including Amine and Cooling tower blowdown)

For disposal, the majority of the liquid is pressed from the solid waste and re-injected back into the ground into Class II injection wells. These liquids are a combination of drilling mud compounds, hydraulic fracturing chemicals, well cleansing acids, and formation fluids. These fluids can be high in naturally occurring radioactive materials (NORMs), hydrocarbons, heavy metals, and other toxics. Such a disposal process is regulated by the U.S. EPA’s underground injection control program, with primacy (authority) granted to states to regulate permitting (COGCC in Colorado, DOGGR in California, RRC in Texas, PADEP in Pennsylvania, Ohio EPA in Ohio, etc.).

This is all outlined in Resource Conservation and Recovery Act (RCRA) Subpart C on Exempt Waste. But because RCRA’s exempt status here is based on the relationship of the waste to exploration and production operations, and not on the chemical nature of the waste, it is possible for an exempt waste and a non-exempt hazardous waste to be chemically very similar.