Rapid OGI Monitoring for Pipeline Leak Repair and NESHAP 6B Compliance

Trihydro’s optical gas imaging (OGI) team supported a refined products pipeline operator in the Pacific Northwest after a potential underground gasoline leak was identified at a pumping station during voluntary fugitive emissions monitoring. The work was conducted in advance of anticipated National Emissions Standards for Hazardous Air Pollutants (NESHAP) Subpart BBBBBB (6B) OGI requirements, and required rapid mobilization, continuous monitoring, and close coordination with the operator to support safe leak confirmation, excavation, and repair under evolving site conditions.

After the initial investigation suggested the leak may be severe, the pipeline operator requested immediate onsite support. Trihydro mobilized a certified OGI thermographer within 24 hours to assist with leak confirmation, emissions monitoring, and health and safety support during excavation and repair. Once the active leak was confirmed, the operator excavated the affected area and installed a stopple upstream to isolate the damaged segment.

Timely repair was important because the pipeline supplied refined products to several major metropolitan areas. The outage contributed to a temporary regional fuel price increase of approximately 16 cents per gallon, drawing attention from state agencies and elected officials. Trihydro maintained continuous availability throughout the repair, adjusting schedules and extending monitoring coverage to support real-time decision-making and reduce risk to personnel and the surrounding environment.

OGI Monitoring for Pipeline Leak Detection and Site Safety

Trihydro integrated OGI monitoring with site-specific safety protocols to support safe work practices during all phases of the response. Key safety and monitoring measures included:

• Conducted hourly checks of the excavated area to support the protection of maintenance personnel and the environment
• Maintained separation from the excavation during welding and other higher-risk maintenance activities, keeping non-essential personnel clear of the work zone
• Worked within engineered controls, including shoring and platforms, to support safe access and stable monitoring positions
• Performed short-duration monitoring intervals to limit personnel exposure while maintaining situational awareness
• Tracked emissions in real time using OGI to inform safe work decisions as site conditions changed

OGI Monitoring for Leak Repair Verification and 6B Regulatory Readiness

Following completion of the permanent repair, Trihydro verified that no emissions were visible using OGI during pipeline re-pressurization. This confirmation, along with the required pressure testing, provided the operator with greater confidence in the integrity of the repair and the success of the overall response effort.

By pairing rapid field mobilization with disciplined safety controls and OGI-based verification, the project demonstrated readiness for emerging NESHAP Subpart BBBBBB (6B) OGI requirements through field implementation under active conditions, and reinforced the value of voluntary monitoring as an early indicator of potential pipeline integrity issues.

Pipeline Leak Repair Results with OGI Monitoring

• Demonstrated readiness for emerging NESHAP Subpart BBBBBB (6B) OGI requirements through field implementation under active conditions
• Mobilized OGI support within 24 hours to support leak confirmation and response actions
• Supported safe repair activities with continuous monitoring and controlled exposure practices during excavation and welding
• Verified no visible emissions upon re-pressurization using OGI to support repair confirmation
• Contributed to restoring pipeline operations supplying multiple metropolitan areas
• Supported response efforts during a regional fuel supply disruption associated with an approximate 16-cent-per-gallon price increase