Underground Cable Installation Case Study: Record-Breaking 3,200 Feet in One Day 


PG&E's four-month timeline meant another fire season with overhead lines still exposed in Forest Ranch. Five weeks later, CPNA had buried 5.5 miles of conduit through volcanic lava cap and layered rock—finished before conventional crews would have completed mobilization. 

When PG&E and C&C Utility Inc. needed underground cable installation in Cohasset, Butte County, the project presented extreme urgency. This high forest fire zone required 5.5 miles of underground infrastructure to eliminate wildfire ignition risk from overhead lines. Unstable soil conditions threatened to compromise conventional trenching effectiveness and extend timelines in an area where residents needed protection from future fires. PG&E required utility grid hardening contractors capable of maintaining production through unpredictable ground conditions while accelerating delivery. 

The Challenge: Unstable Soils in a High Fire-Risk Zone 


Unstable soil conditions throughout the Sycamore project area would have created challenging conditions for conventional trenching methods. Tight working conditions along Cohasset Road further constrained equipment access and staging areas. For a community in a designated high fire-risk burn area, extended construction timelines meant continued exposure to overhead line ignition risk. PG&E needed one-pass trenching contractors who could maintain aggressive production rates through these challenging ground conditions. 

CPNA's Solution: Integrated Installation Through Challenging Conditions 


CPNA deployed its one-pass trenching system for the variable soil conditions. The integrated approach combined excavation, 4-inch HDPE conduit placement, and immediate backfilling into a continuous operation that reduced open trench exposure in unstable conditions. CPNA's equipment maintained an average production rate of 2,000 feet per day through the challenging soils. The continuous placement and backfill process minimized the extended open trench periods that create safety and stability concerns with conventional multi-pass operations, allowing CPNA to maintain consistent production through soil conditions that would have required additional safety measures with traditional methods. 

Measurable Results: Five Weeks Ahead, Record Production 


CPNA accelerated the schedule by five weeks, completing the underground cable installation ahead of PG&E's target timeline. The project achieved an unprecedented production milestone: 3,200 feet installed in a single day—a record never achieved on PG&E's 10,000-mile undergrounding program or any other utility program. Phase 1 of the 5.5-mile installation finished three weeks ahead of schedule, with all conduit successfully installed at 3.5 feet of cover throughout the high fire-risk zone. The accelerated timeline delivered immediate wildfire mitigation benefits, converting overhead distribution to underground infrastructure that eliminates ignition risk from powerlines. Faster completion reduced project costs through compressed overhead and allowed PG&E to energize the protected system sooner, reducing future forest fire risk for Cohasset residents. 

Strategic Takeaway: Production Through Instability 


This Cohasset project demonstrates how specialized utility grid hardening contractors overcome soil instability to deliver record-breaking production in high fire-risk areas. CPNA's integrated underground cable installation methodology eliminated the safety constraints and timeline extensions that unstable soils impose on conventional trenching. The five-week schedule acceleration and record daily production prove that one-pass trenching technology delivers superior outcomes when ground conditions demand both speed and safety. For utilities executing wildfire mitigation programs in challenging terrain, integrated installation services provide the production capacity needed to protect communities quickly. 

Ready to accelerate wildfire mitigation infrastructure in challenging conditions? Contact CPNA to learn how our underground cable installation solutions deliver record production while maintaining safety in unstable soils. 

Project Specifications: 

  • Location: Sycamore, Cohasset Rd., Cohasset, Butte County, CA

  • Scope: 5.5 miles of 4" HDPE conduit 

  • Installation Depth: 3.5 feet of cover 

  • Soil Conditions: Unstable soils, high forest fire/burn area 

  • Production Rate: 2,000 linear feet per day average; 3,200 feet peak daily production 

  • Schedule Performance: 5 weeks ahead of schedule, Phase 1 completed 3 weeks early