Marlene Feist

New digester planned at treatment plant

Marlene Feist, Utilities Communications Manager, No Phone Number Available

Thursday, August 7, 2014 at 3:39 p.m.

New digester planned at treatment plant

Keeping the City's Riverside Water Reclamation Facility operating efficiently and effectively is an important priority for the City. The facility processes an average of 34 million gallons of wastewater every day, protecting the health of our citizens and environment, so it's critical to continue to invest in its effective operation.

This fall, construction will begin on a third solids digester at the facility. Digesters use a microbial process to break down the solids, oils, and suspended particles that are removed from the wastewater at various points at the plant. Final, processed solids are de-watered and spread on fields as fertilizer. About 6,500 tons of these biosolids are generated annually.

The new digester is needed to provide additional capacity at the plant and to provide regulatory redundancy to allow the City to more easily complete maintenance on the other two digesters, which have been in operation since 2008.

In July, the City Council approved an $11 million contract with IMCO General Contractors, of Ferndale, WA, to build the digester and to remove an older concrete digester facility that have been idle for a number of years. The image included here displays the new digester and the facility that will be removed.

The new digester is one in a series of upgrades to the facility since it was first built in 1958 to keep up with advancing technology, improved water quality standards, and odor control for surrounding neighbors.

More work is coming soon, too. Planning and design is under way to add an additional level of treatment. Commonly called the Next Level of Treatment, this project will add membrane technology to further improve the quality of the water that is discharged to the Spokane River. The membranes will remove pollutants including heavy metals, PCBs, and phosphorus. Construction on this $80 million to $100 million project is expected to begin in 2017.

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