class VI permitting

January 12, 2026

Advancing Class VI Permitting: A Lessons Learned Approach to Critical Pressure Modeling and Impact Analysis

Class VI permitting requires robust computational models to demonstrate containment and integrity. A recent development of a Class VI permit application by SCS Engineers revealed restrictions on the ability of the EPA-recommended Method 2 for Critical Pressure (CP) calculations, underscoring the need for a practical, structured approach to Critical Pressure (CP) modeling.

CP modeling is important to the viability of proposed carbon sequestration projects because it determines the size of the Area of Review and the scope and cost of Corrective Action. This blog presents a lessons-learned framework that balances rigor with simplicity and introduces an innovative concept for analyzing the impacts of emerging risks.

The proposed methodology is built on five key elements:

1. Conceptual clarity—defining essential components such as boundary conditions, injection scenarios, and performance metrics.
2. Streamlined implementation—using standardized assumptions and modular design to minimize complexity and improve reproducibility.
3. Parameterization and sensitivity analysis—identifying critical variables and enhancing transparency for regulators and stakeholders.
4. Real-world application—demonstrating feasibility and lessons learned through a test case that highlights practical challenges and solutions; and
5. Forward-looking impacts analysis—addressing novel regulatory and technical questions, including emerging risk pathways and adaptive management strategies.

Applying this framework has shown measurable benefits: improved clarity in model documentation, reduced regulatory review time, and greater confidence in outputs. By emphasizing simplicity, defensibility, and sensitivity, the approach mitigates common pitfalls in current review processes and fosters stronger communication between operators and regulators. Ultimately, this methodology provides a template for consistent, efficient Class VI permitting and lays the foundation for future advancements in risk assessment and regulatory alignment.

To learn more, please reach out to our co-authors at SCS Engineers.

Meet the Co-Authors:

Kacey Garber has professional experience as a geologist and hydrogeologist. Her expertise includes Class VI Underground Injection Control (UIC) permitting for CO2 storage projects, Class I UIC permitting for liquid waste disposal, and environmental permitting and groundwater studies for landfills and coal combustion residual disposal sites.

Tara Gross is a project advisor providing strategic insight and technical oversight for key initiatives, including critical minerals, oil and gas, carbon capture, utilization, storage, underground injection control Class I, II, and VI well permitting, lithium extraction, and Department of Energy grant programs.

Dr. Charles Hostetler is an experienced project manager and subject matter expert in geochemistry, hydrogeology, risk assessment, environmental regulations and permitting, and natural resources assessment. He serves clients in the coal combustion residue, solid waste, real estate, manufacturing, mining, nuclear waste, and governmental sectors.

Additional Resources for Critical Pressure Modeling and a New Standard for Class VI Permits:

• SCS Engineers will present the new approach at several conferences this year, including the 2026 GWPC UIC Conference in Fort Worth, TX, on Thursday, February 12, from 9:30-10:00 AM.
• Article: Groundbreaking Time-Based Model Sets New Standard for Class VI Permits
• Carbon Sequestration & Deep Well Injection