Wastewater Treatment Plant Effluent Treatment Upgrades

Client—City of Astoria, Oregon

Gibbs & Olson provided engineering services for Astoria’s wastewater treatment plant effluent treatment upgrades project. The treatment plant was constructed in the early 1970’s and the existing plant is a 3-cell stabilization lagoon system with aeration in the first and second cells. The treated wastewater is discharged to the Columbia River. There have been no major modifications to the effluent disinfection system since the plant was built. Upgrades were required to comply with the City’s new NPDES permit effluent limits. Improvements include an automated system for chlorine injection for disinfection in the chlorine contact basin, an automated dechlorination system to remove chlorine residual prior to final effluent discharge, chlorine contact basin upgrades, effluent flow measurement, pH control system, and installation of a sonic algae removal/prevention control system.

All new systems and components are sized to handle a flow range of between 1.5 and 23 million gallons per day to ensure they will function properly over the plant’s flow range. The new system was put into operation in January 2014 and total project cost was $1.1 million.