Portland's Big Pipe Project

completed

Portland's Big Pipe is a major public works project completed in 2011 to overhaul the city's wastewater system. It consists of three major tunnel segments: the Columbia Slough Big Pipe (completed in 2000), the West Side Big Pipe (completed in 2006), and the East Side Big Pipe (completed in 2011). The project was designed to reduce combined sewer overflows into the Willamette and Columbia rivers by routing wet-weather flows to the Columbia Boulevard Wastewater Treatment Plant. The project significantly reduced overflow events from about 50 times a year to fewer than four times a year, cutting overflow volume by about 95%.