Balch Consolidation Conduit Project
Designed to reduce the environmental and sanitation impacts of Portland’s combined sewer overflow system (CSO) by controlling sewage overflow into the Willamette River, the Balch Project detours combined sewer and storm water runoff to be conveyed to the Columbia Boulevard Wastewater Treatment plant.
The ground conditions in Portland are known for being extremely challenging and this site was no exception. With soils ranging from aggressive open-graded gravels to very soft clays and silts, this project required high-quality microtunneling equipment paired with high-quality jacking pipe. 6,800 feet of 84-inch diameter and 1,200 feet of 54-inch diameter concrete jacking pipe was installed at depths ranging from 20 to 70 feet below the water table. The 84-inch pipeline was installed in five drives, while the 54-inch pipeline was completed as a single drive.
All pipe installed via microtunneling was reinforced concrete jacking pipe and the production of the pipe was completed in a joint venture between Geneva Pipe & Precast and Cascade Concrete Products. Geneva Pipe & Precast supplied all production equipment, design services, and technical expertise while Cascade Concrete Product produced and tested the pipe at their plant in Scappoose, Oregon.
The project received multiple awards including the prestigious ‘Top Project 2012’ by the Daily Journal of Commerce and the ACEC Engineering Excellence Grand Award: Special Projects 2011.