Sewer plant expansion slated at Liberty Lake

Williams Brother Construction LLC, of Spokane, has landed an $11 million expansion and conversion project at the Liberty Lake wastewater treatment plant.

Work is expected to start later this month, and the project is scheduled to take 18 months to complete, says Dennis Fuller, vice president

The Liberty Lake waste-water treatment plant is located along Harvard Road, northwest of the Interstate 90-Liberty Lake interchange.

The project involves doubling the treatment capacity of the plant, to 2 million gallons of effluent a day from 1 million gallons a day. Such an expansion is designed to handle anticipated growth in the Liberty Lake area over the next 20 years, says Lee Mellish, manager of the Liberty Lake Sewer and Water District.

The sewer district still is seeking approval from the Washington state Department of Ecology to increase its discharge of effluent into the river, and expects to secure state approval by the time the project is completed, Fuller says.

Mellish says Ecology is developing new discharge standards, referred to as total maximum daily loads, and won't approve additional discharge capacity until the new standards are in place.

He says it's a calculated risk to go forward with the expansion without regulatory approval to increase discharge, but the plant is nearing its capacity.

"It was either this or a moratorium" on growth, Mellish says.

He, too, believes the district will have approval before the expansion is done.

In addition to expanding the plant's capacity, the project involves converting the plant to what's called a biological-nutrient removal treatment process, which the Post Falls waste-water treatment plant also uses. The Liberty Lake facility currently uses what's known as an extended-aeration treatment process.

"The new treatment is going to significantly improve the quality of effluent we discharge into the (Spokane) River," Fuller says.

The expansion will enlarge the plant's footprint by about 40 percent, he says.

Mellish says the sewer district has received a $7 million loan from the state Public Works Trust Fund and will use money from its own construction fund to pay for the balance of the project.