The Phase 5 Outfall Project provided critical upgrades to Clark Regional Wastewater District’s wastewater output system, increasing the region’s output processing for the next 50 years. The 900 feet of new pipeline upgrades tying into the Columbia River was completed by a Joint Venture with Advanced American Construction – a marine contractor who employs divers, barge operators, and crane operators. As the General Contractor, Advanced American Construction completed all off shore erosion control, 70 foot deep dive pipeline installation, and barge work. As the onshore contractor, our team constructed the on-shore tie-in of the 48″ HDPE pipeline, on-shore pipeline excavation and installation, and temporary construction of the causeway needed to assemble and float the fabricated steel section of the pipeline to prepare for Advanced American Construction’s work. The on-shore work alone required over 60,000 CY of excavation to place the 500 feet of pipeline forty-feet below elevation.
To overcome the challenges of pipe installation along the shoreline highly affected by the changing tides, we built a temporary causeway – mining approximately 5,000 CY of river material to build the causeway up for excavator access, installing a turbidity curtain, constructing soil wraps to prevent erosion, and working within the fish migratory season to minimize impact to the river. To complete the project, crews worked together to piece together a 700 foot section of the pipeline with flange joints and concrete anchor blocks, floating it on the river and utilizing a barge to position and sink it to grade.