The Point Pinole Tap 115 kV Transmission Line project involved relocating and replacing several existing wooden structures with tubular steel poles near Richmond, California. The proposed foundation sites were located in close proximity to Giant Marsh, a protected wetland habitat, and were subject to strict environmental regulations. Once complete, the planned upgrade will deliver more power and improve service reliability to the customers in the area.
Pacific Gas & Electric Company
Wilson Construction Company
Crux was selected to provide specialty design-build services for four foundations on the structure upgrade portion of the project. Prior to construction, a geotechnical investigation of the surrounding area showed deep, soft soils with varying levels of groundwater, requiring a foundation that could be designed for varying subsurface conditions. Micropiles were selected as the optimal foundation solution because they can be installed within a small footprint using low impact approaches. Crux’s equipment is compact and componentized, and all foundation work was successfully completed within the permissible 15-foot-wide area. In total, Crux drilled and installed 42 piles, ranging from 55 to 70 feet in depth.
The unstable soils and ground conditions did not permit standard proof testing, which requires an even ground line to support wood cribbing under a test beam and ram. Crux utilized an alternative testing method that took place once all piles and hardware were properly installed. In this method, the test ram was placed directly on the micropile cap and tensioned to the maximum factored load.
Specific challenges included congested spacing and unpredictable weather conditions. Throughout the duration of the project, crews encountered periods of heavy and unseasonable rainfall, resulting in slippery and muddy ground conditions. To minimize risks and avoid possible delays, equipment and materials were placed nearby to increase accessibility of resources. With multiple contractors in a confined space simultaneously and a limited construction area, high levels of communication and close coordination between crew members became paramount to ensuring safety.
All micropiles were installed on-schedule and with no impacts to the surrounding wetlands. Crews worked diligently to ensure all work was done in a safe and environmentally compliant manner, earning an exceptional safety review from the client.