Wastewater Processing
- The existing treatment plant went on line in February 1981.
- The City of Hermiston treats approximately 1.5 million gallons per day of domestic wastewater. The plant is a secondary treatment process using a rotating biological treatment system.
- Disinfection of the effluent is completed using chlorine gas. After disinfection, the city has two discharge points: discharge 001 is to the Umatilla River and 002 is to LGW Ranch for irrigation of fodder crops.
- Solids processing is accomplished using two identical anaerobic digesters. This is a high rate primary/secondary system. In 1999 the city added a 4,000,000 gallon sludge storage lagoon to aid in the handling of its class B biosolids. There are also 12 drying beds which are used during the warmer months.