When the Bull Run Hydroelectric project was built in the early 1900s, it was considered a feat of engineering and skilled construction. Sited in what was then a remote wilderness about 35 miles east of Portland, Ore., the project comprised an integrated network of construction and engineering : dams on the Sandy and Little Sandy Rivers, more than three miles of canals and tunnels, a wooden box flume to transport water nearly three miles to the man-made Roslyn Lake reservoir and a powerhouse on the banks of the Bull Run River.
Following design by Mount Hood Railway and Power Co., its subsidiary Mount Hood Construction Co. began construction in 1909. The job was completed in 1912 by Portland Railway Light & Power, a predecessor to Portland General Electric (PGE). The power station would serve Portland’s growing population for decades, but in 1999, after nearly 94 years of operation, PGE determined that the environmental costs associated with relicensing were too high to justify continued operation. In 2007, PGE began decommissioning. Restoring the Sandy and Little Sandy Rivers to their original flows was a key component.
Because it can moderate the damaging effects of earthquakes, base-isolation is a technique used primarily in seismically active regions. ENR takes a look at some of the largest applications of base-isolation technologies in the world.