Contractors Northwest, of Coeur d'Alene, is the apparent low bidder, with a bid of about $5 million, to construct a wastewater treatment plant for the city of Plummer, Idaho.

Alan Gay, a project manager for the Spokane office of Anchorage, Alaska-based USKH Inc., which designed the project, says the city has accepted Contractors Northwest's bid, and a contract will be awarded soon for the first phase of the work, which will entail constructing the facility at a site north of Plummer. Later, the city likely will award a $750,000 contract to the company to demolish the city's current lagoon system and restore the land it sits on, a project that could take up to two years to complete, Gay says.

In the first phase, Contractors Northwest will construct an 85- by-65-foot multibasin concrete system for extended aeration treatment, including preliminary treatment basins and aeration basins, as well as clarifiers and aerobic digesters. That system will be designed to treat an average daily flow of up to 315,000 gallons of wastewater, with a peak capacity of 630,000 gallons a day. The project also will include installation of four filters, called ion exchange upflow filters, that are designed to reduce phosphorus to a level of 50 micrograms per liter, Gay says.

The plant is designed to be expanded later to double its initial capacity, Gay says. It is needed because the current system is designed for flows of about 130,000 gallons a day, but the community produces around 180,000 gallons of wastewater a day. Also, the lagoon system is not designed to reduce phosphorus levels in the treated wastewater, Gay says.

Separately, USKH is designing upgrades for the city of Omak's wastewater-treatment plant, Gay says. That $400,000 project will double the plant's capacity to 4 million gallons a day, and will include replacing the screens and grit removal systems there, as well as converting a concrete basin into an aerated sludge storage basin, which will expand its capacity. He says Omak expects to seek bids for construction of that project late this summer.