The Oak Harbor City Council voted unanimously last week to approve contract negotiations with Carollo Engineers for a new Oak Harbor wastewater treatment facility. The contract will likely go before council by early May.

At present, a portion of the city’s wastewater is processed at the Windjammer Park treatment plant at the end of City Beach Street. Constructed in the 1970s, the facility has reached the end of its useful and practical life, said City Engineer Eric Johnston.

A second wastewater treatment plant located on the Seaplane Base is now threatened by flooding as a result of an effort to restore the Crescent Harbor marsh area. The flooding puts at risk the long-term viability of a treatment plant at Crescent Harbor, Johnston said. That site was favored by some in an effort to move the sewer plant from the Windjammer Park area.

Eight firms submitted proposals to Oak Harbor for the wastewater treatment facility project. From that list, public works standing committee members Danny Paggao, Rick Almberg and Beth Munns, in addition to Mayor Jim Slowik and several city staff members, interviewed four firms last month.

“There wasn’t a rock unturned,” Munns said of the selection process. “We should get started.”

Carollo Engineers of Arizona will first develop a facility plan, or the “what and where” of the project, Johnston said.

“The facility plan will examine the long-term life cycle costs, financial impacts to rate payers, effluent disposal, solids handling and public transportation,” he said.

The next step is to develop a scope of work, which will include extensive public involvement in the form of stakeholder, public and City Council meetings.

The city will meet with Whidbey Island Naval Air Station, Island County and multiple agencies including the Army Corps of Engineers, Department of Health, Department of Natural Resources and Department of Fish and Wildlife, among others, to develop the facility plan, Johnston said.

“This is a very, very expensive project,” he said.

Depending on the final location and treatment methods used, the cost will range from $30 to $60 million, he said. If all goes as planned, construction is expected to start in 2017.