Replacing critical infrastructure without increasing permitting risk
Reliable operation of the Fluid Catalytic Cracking Unit (FCCU) is essential for refinery performance. When our client determined that the aging reactor at its refinery needed upgrading, the project introduced a potential air-permitting challenge. Located in a severe ozone nonattainment area, the refinery operates within an especially stringent regulatory environment. Because the work qualified as a physical modification to a major emissions source, it could trigger Major New Source Review (Major NSR) permitting, one of the most rigorous air-permitting programs under the U.S. Clean Air Act.
For refinery operators, entering Major NSR can add significant cost, extend the project schedule and require major new emissions control equipment. Rather than waiting for permitting challenges to emerge, the refinery proactively engaged Onterris to develop a strategy that would not add to the existing regulatory requirements while supporting reliable facility operations.
Building a permitting strategy around operational reality
Working alongside refinery, environmental and operations teams, Onterris developed a permitting strategy grounded in a thorough understanding of refinery operations. The team evaluated historical operating data, evaluated future operating scenarios and assessed both upstream and downstream process impacts to understand how FCCU upgrades would affect emissions.
Using projected actual emissions and excluding emissions that the unit “could-have-accommodated”, the analysis demonstrated that increases in nitrogen oxides (NOx) and volatile organic compounds (VOCs) would remain below the five-ton netting trigger. This allowed the upgrades to proceed under a minor NSR permit instead of entering the more complex Major NSR permitting process.
The evaluation also established that Best Available Control Technology (BACT) for sulfur dioxide did not require installation of an expensive wet gas scrubber. By combining a technical analysis with practical operating limits, the permitting strategy aligned regulatory requirements with operational realities.
Bringing engineering, operations and environmental expertise together early helped speed up permitting, prevent additional regulatory complexity and create measurable value through better planning
Delivering measurable business value
The permit application was submitted using the Texas Commission on Environmental Quality’s expedited permitting program and was issued within a six-month timeframe. The approval enabled the client to move forward with replacing critical equipment while maintaining the project’s schedule.
Beyond securing the permit, the strategy reduced financial and schedule risk. Avoiding Major NSR shortened the regulatory pathway, while demonstrating that the existing controls are protective of the environment, preventing a potential capital investment estimated in the hundreds of millions of dollars. The project established practical operating limits that support long-term compliance without creating unnecessary operational or financial constraints.
Navigating complex permitting with confidence
Onterris worked closely with this client to navigate a complex framework of overlapping federal and Texas air regulations across multiple permitting requirements and project activities.
The team integrated emissions analyses, air dispersion modeling, BACT evaluations, Nonattainment NSR and Prevention of Significant Deterioration (PSD) applicability and public notice obligations into a cohesive permitting strategy that created a clearer path to authorization while supporting client business objectives.
By bringing together engineering, operations and regulatory expertise early in project planning, Onterris helped the client authorize the project without creating additional regulatory complexity, protect the project schedule and make informed investment decisions that supported both compliance and long-term operational performance.