Oct 29, 2019

Combined Sewer Overflow (CSO) Tank under Spokane, Wash. Plaza Complete

A combined sewer overflow (CSO) tank built under a new plaza in Spokane, Wash. has been completed and is set to go online in 2020.

A combined sewer overflow (CSO) tank built under a new plaza in Spokane, Wash. has been completed and is set to go online in 2020.

Underneath the new pedestrian plaza in Spokane, Wash., is a combined sewer overflow (CSO) tank, which has caused the closure of the Monroe Street Bridge and traffic blocks for years, according to KXLY News.

The tank is one of two dozen built across the city and will be online sometime in 2020, reported KXLY News.

The tank can collect approximately 2.2 million gal of storm water from city streets before it is discharged to the city’s water plant. Large, white pipes will collect the smell it emits, diffusing and then releasing it elsewhere.

"From the very beginning, we began to look and explore the concept of integration. The work led to our integrated clean water plan, which saved some $150 million and gave us better pollution reduction benefits," said Mayor David Condon to Spokane Public Radio. "It sparked the idea that we should create above-ground benefits when we’re building below-ground infrastructure. This plaza is a perfect example of that.”

Its construction is part of an effort to keep the Spokane River clean, a project which has been in development for about three years. A connecting path underneath the Monroe Street Bridge will be built eventually, according to KXLY News.

"Just to get this size of a structure on the side of a hill was very challenging," said Garco Construction Project Engineer, Justin Ludwig.

The plaza is decorated with metal art pieces celebrating the historic role of native fishing at the site.

“These falls over here, for 100 days every year, our tribe would fish an average of a thousand salmon out of this river," said Jeff Ferguson, the project's lead artist. "We would pull, on average, 30-pound salmon. They would get as large, in June, as 110 pounds and over five feet long. When they would ride away with the horses, the salmon would drag from the saddle horns. It was an amazing site to see.”

The plaza will soon be closing for the winter to protect the concrete, reported KXLY News.

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