LOTT Clean Water Alliance provides wastewater management services for approximately 120,000 people in Thurston County, Washington. Since 1994, LOTT’s Budd Inlet Treatment Plant has employed biological nutrient removal (BNR) to protect water quality in Budd Inlet, where most treated water is discharged. LOTT is recognized as an industry leader in progressive treatment approaches that meet the most stringent discharge limits in the Puget Sound region.

LOTT recently completed a major construction project to upgrade the BNR process. The project optimized the biological treatment process, replaced aging equipment, enhanced operational control and flexibility, and increased process reliability.

The Biological Process Improvements (BPI) project was many years and many team members in the making. Project design began in 2016 with active engagement of plant and engineering staff and use of innovative design tools like 3D modeling. LOTT was first in the state to utilize an innovative alternative procurement process for contractor selection. Construction began in 2020. Careful coordination over 12 full plant shutdowns ensured wastewater treatment was not disrupted. The first two new treatment trains were started up in March 2022, the third in July 2022, and the remaining two trains in March 2023. Overall, the BPI project was delivered on time and on budget. Funding for the $29 million project was supported by low interest loans through the Department of Ecology Water Quality Program and Department of Commerce Public Works Board.

Resulting treatment performance is excellent, with total inorganic nitrogen levels as low as 0.4 mg/L and an average tracking at 1.6 mg/L, compared to the 3 mg/L permit limit. This high performance improves water quality in Budd Inlet, provides capacity to meet community growth, and delays needing to build new costly treatment capacity. It also prepares LOTT to meet even more stringent discharge permit limits anticipated in the future.

The upgrades also significantly reduced energy usage through installation of highly efficient pumps, enhanced aeration control, and advanced controls technology. Energy savings are estimated at 2.5 million kilowatt-hours per year, which represents utility cost savings of over $180,000 annually and offsets 1,143 tons of CO2, reducing LOTT’s carbon footprint. 

Because of state efforts to reduce nutrient inputs into Puget Sound from wastewater treatment plants, LOTT’s success with the second generation BNR upgrade has been of great interest to others. LOTT has given many presentations and tours to share information about this project as a valuable example of what is possible with BNR.

NACWA awarded LOTT Clean Water Alliance a 2024 National Environmental Achievement Award in the Operations & Environmental Performance category for its innovative and effective project. Congratulations to everyone involved!