Five and a half miles through solid granite and basalt—the kind of rock formation where conventional trenching burns through budgets and schedules. CPNA maintained 2,000 feet per day of conduit installation for weeks, production PG&E had never seen in these conditions. Phase 1 finished three weeks early. 

When PG&E and C&C Utility Inc. needed underground infrastructure along Gaston Road in Alleghany, Washington, the project faced some of the most demanding geological conditions in the region. This high forest fire zone required 5.5 miles of underground cable installation through solid rock formations that would challenge any trenching operation. The utility needed integrated cable installation services capable of maintaining production and controlling costs despite extreme ground conditions. 

The Challenge: Solid Rock and Extreme Variability 


Solid rock comprised of granite and basalt dominated the project corridor. Extreme variations of cobble and large rocks throughout the installation route compounded the difficulty, making both trenching and backfilling operations challenging. Tight working conditions along Gaston Road limited equipment access and staging flexibility. These combined geological conditions would extend timelines and increase costs with conventional trenching approaches. PG&E required one-pass trenching contractors capable of maintaining consistent daily production through these demanding rock formations. 

CPNA's Solution: Specialized Equipment for Rock Conditions 


CPNA deployed its one-pass trenching system for the demanding rock formations. The integrated approach combined rock excavation, 4-inch HDPE conduit placement, and backfilling into a continuous operation. CPNA's equipment maintained an average production rate of 2,000 feet per day through the solid rock, handling the extreme geological variations without requiring multiple equipment passes. The continuous operation allowed CPNA to maintain production efficiency through conditions that would extend conventional project timelines. 

Measurable Results: Record Production, Significant Cost Savings 


CPNA achieved production levels PG&E had never seen on a project before, maintaining 2,000 feet per day average through extreme rock conditions. 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 unprecedented production delivered multiple areas of value-added solutions and generated cost savings to PG&E's overall budget. The accelerated timeline allowed earlier system energization, advancing wildfire mitigation objectives for the Alleghany community. 

Strategic Takeaway: Production and Value in Extreme Conditions 


This Alleghany project demonstrates how specialized integrated cable installation services deliver superior outcomes when extreme geological conditions threaten project economics. CPNA's one-pass approach maintained production rates through granite and basalt that conventional methods struggle to handle efficiently. The combination of unprecedented production and significant cost savings proves that turnkey underground cable projects deliver measurable value when rock conditions demand both technical capability and operational efficiency. For utilities managing infrastructure budgets while executing wildfire mitigation programs, integrated services provide the cost control needed alongside schedule performance. 

Ready to control costs on your next underground installation in challenging geology? Contact CPNA to learn how our integrated cable installation services maintain production through extreme rock conditions. 

Project Specifications: 

  • Location: Alleghany, Gaston Rd., Washington, CA 

  • Scope: 5.5 miles of 4" HDPE conduit 

  • Installation Depth: 3.5 feet of cover 

  • Geological Conditions: Solid rock (granite and basalt), extreme variations of cobble and large rocks, high forest fire/burn area 

  • Production Rate: 2,000 linear feet per day average 

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

  • Cost Impact: Multiple value-added solutions, cost savings to overall budget