LOTT to expand Budd Inlet wastewater plant capacity 

The LOTT Clean Water Alliance plans to raise the Budd Inlet Treatment Plant’s influent pump station capacity to 75 million gallons per day from 59 million gallons per day.

The LOTT Board of Directors received an update on the Influent Pumping and Emergency Power Improvements Project at a meeting on Wednesday, Sept. 10. 

Engineering Director Kip Summers said the project is identified in the capital improvement plan as a new capacity project with a budget of $27.12 million. 

LOTT relies on the plant as its main wastewater site. The facility currently processes an average of 24 million gallons per day, which is  equal to about 20 Olympic-sized pools of wastewater. 

Summer noted flows vary with the seasons and time of day, reaching lows of 4 million gallons per day (mgd) in summer nights and highs of 65 mgd during peak periods. The station uses four pumps, each capable of processing 18 mgd.

Capacity

LOTT’s capacity planning shows the plant will need 90 mgd by 2050.  

To meet demand, LOTT’s project has been split into two phases. The first phase will replace the pumps and modify the wet wells to reach 75 mgd. A second phase, expected closer to mid-century, will replace the force main to lift the capacity to 90 mgd. 

Summers said the influent pump station basis of design report was completed in 2024. 

The report recommends expanding from the number of pumps to achieve the 75 mgd target. 

“The layout using five pumps allows us to install two smaller duty pumps that will be our main workhorses and operate efficiently for those average days and lower flows at night,” Summers said 

Generator upgrades 

The replacement of power systems is also part of the project. 

Two of the headworks generators date back to 1982, while a third was installed in 2004. They supply electricity to the influent pumps, headworks building, ultraviolet disinfection system and effluent pumping. 

A generator replacement memorandum prepared from 2023 recommends replacing the 400 kilowatt and 500 kilowatt units with three new 1,000 kilowatt generators.  The larger units would provide enough capacity for higher pumping demand and secure backup power for treatment during outages. 

Washington State Department of Ecology guidance, known as the Criteria for Sewage Works Design or the “Orange Book,” requires treatment plants to maintain at least primary treatment or disinfection during power interruptions. 

Summers said the new generators adhere to those standards and address the end of useful life for the two original units. 

“Two of those influent backup generators are 40 years old. They’ve lived out their useful life, and we need to be replacing them,” Summers said. 

In terms of construction impacts, Summers said it would disrupt access near Gate Four, the main entrance to the plant, and would also require careful sequencing of shutdowns. 

Wet well modifications, a revised pumping layout, electrical and HVAC work, and replacement of the fuel storage tank are part of the scope. 

He said LOTT is now preparing a refined basis of design that would select major equipment, model wet well hydraulics, size fuel storage, and evaluate ventilation and electrical needs. 

“There’ll be a lot of shutdowns that will require detailed planning,” Summers said. “To do all this work, there’s a lot of staff workload impacts when we implement these large projects.” 

LOTT expects to return to the board by mid-2026 with the refined basis of design, a revised cost estimate and construction schedule.