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Eastside Big Pipe completed and put into service

by: Sue Bednarz A unique overhead view of the very deep diversion structure constructed in the middle of the intersection of S.E. Insley at 18th in Westmoreland – the very southernmost point of the Eastside Big Pipe Project. If this excavation doesn’t look that deep to you, compare its size with the automobile parked near it at the upper right!

With a surprising lack of flourish or publicity, the Portland Bureau of Environmental Services ended years of excavation and construction in November, and switched sewage outfall lines to the Eastside Big Pipe, which carries sewage and stormwater runoff north to the Swan Island pumping station and ultimately to the Columbia Boulevard sewage treatment facility, instead of spilling rainwater overflow mixed with sewage into the Willamette River.

At one time, there was no sewage treatment, and Portland's combined sewer system just went into the river. By the mid-Twentieth Century, the treatment facility had been built in North Portland, and sewer lines were rerouted to ship the sewage and stormwater there. But, even a light rain in the Rose City was enough to fill these lines to overflowing, so every single time it rained at least a tenth of an inch in 24 hours, there was sewage in the river again.

It was to solve that problem that Portland's biggest-ever public works project resulted in huge underground tunnels to collect stormwater runoff and sewage, and send it all to the treatment plant to keep it out of the Willamette River. When the Westside tunnel was completed, the BES turned to the Eastside, and started by carving a huge, deep shaft just south of OMSI, on the Portland Opera parking lot, and then lowering and assembling a giant boring machine dubbed 'Rosie' into it, to tunnel north to Swan Island, passing several other deep access shafts on the way.

When that job was done, 'Rosie' was hauled out at Swan Island, barged upriver, and again lowered into the 'Opera Shaft', this time aimed southeast….to bore towards the terminus, a huge shaft constructed between S.E. 17th and 18th on the north side of McLoughlin Boulevard, where motorists and residents have watched huge cranes at work for years.

When 'Rosie' finished that job, early in 2011, she was disassembled, hauled out of the McLoughlin terminus shaft in pieces, and then resold by the tunnel contractor, alas, as scrap metal. An ignominious end for a fine tunnel boring machine, with a name and a personality.

But, while this was going on, there was one more major related project - a secondary southernmost shaft dug in the middle of the intersection of S.E. 18th and Insley Street three years ago, into which a smaller, but still impressive, tunneling machine was turned loose to bore northward to the bigger shaft on the north side of McLoughlin in the Brooklyn neighborhood.

This secondary project connected to the 'Insley Collector', a major outfall into the Willamette River, and diverted the collected sewage and rainwater from a large area of Southeast Portland from the outfall pipe to the Big Pipe terminus at McLoughlin.

In mid-November, with no fanfare, the project ended and the Big Pipe began to do its work. From now on, any sewage spills into the river will occur only when severe rain events overload the Big Pipe, which is estimated to happen an average of four times each winter, and once every third summer - a vast improvement.

Somewhat ironically, the Eastside Big Pipe was placed into service at just about the moment when Portland actually had one of those unusual rain events - over three inches of rain fell in three days, November 21-23.

But in the future there will be very, very few warnings to stay out of the river for a few days after rain falls in Portland.