Both the liquids and the solids produced by Oak Harbor’s new sewage treatment plant are going to be put to use.
Oak Harbor City Council members on Tuesday approved a $78,000 increase in a contract with consultant Carollo Engineers to include the time and materials necessary to add an effluent reuse system to the facility being built in Windjammer Park.
Two years ago, the council decided to invest in a $14.5-million belt dryer that will turn the solids into a crunchy material that can be sold as fertilizer.
Project engineer Brett Arvidson explained to the council Tuesday that irrigating about 15 acres of Windjammer Park costs the city about $40,000 a year, so it’s both cost effective and environmentally wise to reuse the water that comes from the plant.
If it’s not reused, the water would be released into the bay.
Arvidson said the reuse capacity wasn’t part of the original plans because the city’s reuse permit had expired and the state was issuing new administrative rules for reuse, so the staff was unable to determine the requirements and costs until now.
Under new administrative rules, reused water has to have an “A-plus” classification in order to be in contact with humans, which requires a higher level of treatment, Arvidson said. The water that the plant will produce has an “A” classification.
Arvidson said the amount of treatment necessary for the higher classification necessary to reuse the water in the splash park planned for the park would be cost prohibitive.
The alterations to the system for reuse are minor, requiring the addition of a tank and a pump, as well as minor piping modifications. Under state rules, the pipes in the park will have to be purple; signage and public education are also required.
The city will have to get a permit through the state Department of Ecology.
“If we want to expand to another park or do a car wash it’s relatively easy because the regulatory framework is in place,” Arvidson said.
The sewage treatment plant is scheduled to start up next summer. The reuse system will begin shortly afterward.