Cal/OSHA Fines Firms After Deadly Tunnel Collapse
State regulators cited two companies for safety violations following a fatal incident at the Canyon Tunnel project.
Updated on Oct. 22, 2026 in Unions
Cal/OSHA has issued $212,500 in citations to two employers after a collapse at the Canyon Tunnel project in Knights Ferry left one worker dead and another seriously injured. The agency determined that the employers failed to provide adequate ground support as required by state tunnel safety standards.
Why it matters
The citations highlight critical enforcement actions regarding workplace safety standards in California tunnel construction projects. Ensuring compliance with ground control regulations is essential to preventing future accidents and protecting the lives of workers in high-risk environments.
Cal/OSHA proposed $117,500 in penalties for the Clovis-based Provost & Pritchard Engineering Group and $95,000 for Antioch-based Drill Tech Drilling & Shoring Inc. The companies are required to meet safety standards that mandate inspections of ground support systems upon initial entry into tunnels.
The players
Cal/OSHA
This is the California Division of Occupational Safety and Health, the state agency responsible for enforcing worker safety and health regulations.
Twyla Capurro
She was a 35-year-old geologist who died while working at the Canyon Tunnel construction project.
Provost & Pritchard Engineering Group
This civil engineering firm based in Clovis provides professional engineering and consulting services across California.
Drill Tech Drilling & Shoring Inc.
This Antioch-based company specializes in geotechnical drilling, shoring, and underground construction services.
The details
The collapse occurred 200 feet inside the irrigation water diversion tunnel, trapping 35-year-old geologist Twyla Capurro and a colleague. Investigators found that work was permitted to proceed without the necessary removal or support of dangerous ground conditions.
Timeline
The Canyon Tunnel collapse occurred on April 14, 2026.
Political Context
This enforcement action aligns with the strict requirements of California tunnel safety standards regarding ground control. The opposition and affected firms may argue that the penalties are disproportionate or dispute the technical findings regarding the site-specific ground conditions at the time of the incident.
The state's move to impose significant fines serves as a regulatory reminder of the legal obligations companies have to ensure site safety for employees. Taxpayers and residents in California benefit from stricter oversight, which is intended to prevent construction disasters that can halt infrastructure progress and endanger lives.
The takeaway
Workplace safety remains a critical regulatory priority to ensure that engineering firms and contractors maintain rigorous ground support standards. Employers must adhere to documented safety protocols to protect staff and avoid significant financial penalties from state oversight agencies.
Further reading
For more information on labor safety enforcement, visit the Unions section.
Source note: This article includes information reported by Insurance Journal.
