The Class VI Rule requires Class VI permit applicants to develop and implement a comprehensive testing and monitoring plan for their projects that includes injectate monitoring, corrosion monitoring of the well’s tubular, mechanical, and cement components, mechanical integrity testing, pressure fall-off testing, groundwater quality monitoring, carbon dioxide plume and pressure front tracking, and, at the UIC Program Director’s discretion, surface air and/or soil gas monitoring [40 CFR 146.82(a)(15); 146.89; 146.90]. 

The purpose of the UIC Program’s evaluation of the applicant’s proposed Testing and Monitoring Plan is to ensure that the testing and monitoring procedures will be appropriate to planned operations, the well’s construction, and site-specific geologic conditions. The UIC Program should ensure that the Testing and Monitoring Plan is designed to generate information over the duration of the project to: 

• Demonstrate that the well is maintaining mechanical integrity, the site is operating as planned, and the carbon dioxide plume and pressure front are behaving as predicted; 

• Provide essential points of comparison for modeled predictions, allowing for validation of the AoR delineation model and helping to address uncertainties during AoR reevaluations; and 

• Form the basis of the non-endangerment demonstration that must be made before the owner or operator may proceed with site closure. 

The UIC Program should also ensure that planned monitoring locations, methods, frequencies, parameters, etc., contribute to a comprehensive, tailored strategy for evaluating the performance of the project against modeled predictions and determining how other required activities will be implemented. 

See the UIC Program Class VI Well Testing and Monitoring Guidance for additional information on testing and monitoring procedures for Class VI projects; also see the UIC Program Class VI Well Project Plan Development Guidance for additional information on evaluating Testing and Monitoring Plans. 

Source: Environmental Protection Agency. (2018, January). Geologic Sequestration of Carbon Dioxide Underground Injection Control (UIC) Program Class VI Implementation Manual for UIC Program Directors.  Page 56. Retrieved from