Two of Thurston County’s wastewater treatment plants recently earned recognition for their exceptional performance. The Grand Mound and Tamoshan Wastewater Treatment Plants received 2023 "Wastewater Treatment Plant Outstanding Performance" awards from the Washington State Department of Ecology. This recognition highlights the Water and Sewer Utilities Operations Team’s incredible dedication, skill, and teamwork behind these essential services.

The Grand Mound Wastewater Treatment Plant, constructed by Thurston County in 1999, serves 425 customers, including 90 commercial connections. It features an extensive collection system of 15.2 miles of sewer mains and uses an oxidation ditch process to treat wastewater before discharging it into the Chehalis River. 

Consistently meeting and exceeding discharge permit requirements has been a hallmark of the Grand Mound plant's operations. “Maintaining high treatment performance with variable influent quality is a significant challenge,” noted Joe Plahuta, Senior Water Resources Engineer. “Our team’s diligent process monitoring and adjustments ensure we continue to protect the Chehalis River's water quality and support the area's growth.” Future plans for the plant include the Phase I Wastewater Treatment Plant Improvement Project to increase capacity and meet changing permit requirements.

The Tamoshan Wastewater Treatment Plant received the award for the third consecutive year. Initially constructed by a developer in the mid-1970s and transferred to Thurston County in the early 1980s, the plant serves 115 connections, including Beverly Beach. Following its acquisition by Thurston County, the Tamoshan sewer system underwent multiple capital improvements to meet permit standards. It operates with a sequencing batch reactor system, which discharges treated water into Budd Inlet. 

“The consistent performance at the Tamoshan Wastewater Treatment Plant showcases our team’s skill and dedication,” said Plahuta. “Their ongoing professional development and proactive optimization of treatment processes keep us ahead of regulatory requirements.” 

The diverse operational strategies in all four of the county’s service areas offer valuable lessons and best practices shared across the team. Because every facility is unique, the team must manage different process variables at each site. “Our team’s adaptability and adherence to best industry practices are the foundation for our program,” Plahuta added.

“These outstanding performance awards highlight the professionalism of Thurston County’s Water and Sewer Utilities Operations Team. Their unwavering commitment to protecting our receiving waters and providing excellent customer service ensures our wastewater management systems' continued success and reliability,” said Tim Wilson, Thurston County Public Works Water Resources Division Manager.

Aerial view of the Grand Mound Wastewater Treatment Plant

Aerial view of the Tamoshan Wastewater Treatment Plant