Wastewater Treatment Plant Dewatering Facility

This project was needed to address the City’s biosolids removal needs at the Wastewater Treatment Plant. In August 2016, the City purchased the centrifuge equipment and the pre-fab building for this project. This contract is to construct the building and install the equipment. Once this project is completed, the City will be able to process our bio-solids by dewatering them to a 20% solids consistency or “cake” that can be transported to the landfill.

Historically, the City had land applied liquid biosolids onto fields in the Siletz Valley. We had been contracting to have 1.8 to 2.0 million gallons per year of liquid Class B at approximately 2.0 to 3.0 % solids (or 97% water) dredged, screened, hauled and applied to the fields from one of two sludge holding lagoons at the wastewater plant. This process has served us well, but in the past 10-15 years we have lost some of our fields and have faced challenges from neighbors of the fields that do not want the biosolids in their area.

In 2015, we only applied 600,000 out of the 2 million gallons produced. In 2016, we found there were no fields available. Consequently, we have been building an excess inventory in the holding lagoons and we needed to develop a short term solution to dispose of our biosolids as soon as possible. City Council reviewed options on how to manage the City’s biosolids or sewer sludge on June 20, 2016 during a Council works session. In the meeting, we discussed the short term solution for removing the biosolids from the plant due to the lack of available fields. The outcome was to purchase and install the dewatering equipment and haul to the landfill.

The new treatment plant was completed in September, 2017.

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