PG&E needed to lay cable through twelve miles of basalt and limestone formations where trenches had collapsed on previous crews. Traditional methods would put workers inside those same unstable conditions for weeks. CPNA's rock saw system eliminated trench entry entirely—maintaining 1,000 feet per day with crews positioned safely above the cut. 

When PG&E and C&C Utility Inc. required underground infrastructure along Caribou Road in a remote section of Caribou, CA, the project presented serious safety challenges. This 12-mile installation demanded solutions for unstable soil conditions that had previously compromised trench safety on similar projects. The utility needed one-pass trenching contractors capable of maintaining production in a remote location while protecting crew safety in unpredictable ground conditions.

The Challenge: Unstable Trenches in Remote Rock Formations 


Dense layered rock, cobble, limestone, and basalt dominated the native soils along the project corridor. Previous trenching methods had struggled to maintain safe trench conditions due to soil instability. The combination of hard rock requiring excavation and unstable conditions presented conflicting demands: aggressive rock cutting combined with worker safety protection. Tight working conditions and the remote location compounded these challenges, limiting equipment access. PG&E required specialized contractors who could maintain consistent production while eliminating the need for workers to enter unpredictable and unstable trenches. 

CPNA's Solution: Integrated Rock Cutting for Enhanced Safety 


CPNA deployed a specialized dual-equipment approach for the demanding safety and geological conditions. The solution combined a reverse pre-cut rock saw operating in tandem with CPNA's ST2 trencher to cut through the rock formations and place HDPE pipes in a continuous operation. The rock saw pre-cuts the formation, allowing the trencher to place conduit ranging from 2-inch to 6-inch HDPE at the specified 3.5-foot depth while continuously backfilling. The approach maintains consistent installation of 1,000 feet safely by keeping workers positioned away from the unpredictable and unstable trench zone throughout the operation. 

Measurable Results: Consistent Production, Zero Trench Entry 


CPNA's dual-equipment approach is maintaining consistent 1,000-foot daily production through the challenging rock and soil conditions on this ongoing 12-mile project. The integrated rock cutting and trenching system allows installation to proceed without requiring workers to enter the trench, eliminating the safety exposure that had compromised previous work in these soil conditions. For a remote location where equipment access is limited, the ability to maintain production while keeping crews out of hazardous trench conditions delivers critical safety value alongside schedule performance. 

Strategic Takeaway: Safety Through Integration 


This Caribou project demonstrates how specialized one-pass trenching contractors solve complex safety challenges in demanding geological environments. CPNA's integrated rock saw and trencher approach eliminates the worker exposure that makes unstable soil conditions dangerous, while maintaining production through rock formations that require aggressive cutting. For utilities managing infrastructure projects in remote areas with challenging geology, integrated solutions provide the safety controls needed to protect crews while delivering consistent installation performance. When soil instability threatens both crew safety and project timelines, specialized equipment integration proves essential. 

Ready to improve crew safety on your next remote underground installation? Contact CPNA to learn how our integrated rock cutting solutions maintain production while eliminating trench entry requirements. 

Project Specifications: 

  • Location: Caribou Rd., Caribou, CA 

  • Scope: 12 miles of 2", 4", and 6" HDPE conduit (ongoing project) 

  • Installation Depth: 3.5 feet of cover 

  • Geological Conditions: Dense layered rock, cobble, limestone, basalt; unstable soil conditions; remote location 

  • Equipment: Reverse pre-cut rock saw in tandem with ST2 trencher 

  • Production Rate: 1,000 linear feet per day consistent 

  • Safety Achievement: Zero trench entry required; workers positioned away from unstable trench zone