Coeur d'Alene-based Contractors Northwest Inc. has submitted an apparent low bid for a $4.9 million project to upgrade portions of a wastewater treatment system that serves the city of Chelan in Central Washington.

Contractors Northwest President Bryan Taylor says the city was scheduled to review the bids for the planned second phase of upgrades at the wastewater treatment facility on Jan. 12. Assuming its bid is approved, he expects Contractors Northwest to be able to begin work on the project around March 1 and to complete the upgrades by early 2013.

Jason Cates, a Contractors Northwest project manager, says the improvements are planned for an upper area and a lower area of the wastewater treatment facility system that are about 10 miles apart.

The lower-area site is off Chelan Falls Road along the Columbia River, Cates says. More work will be done at the upper site, on the east end of Lake Chelan.

The work at the lower site will include building a new head works building, which screens and diverts the effluent sludge, and a new primary clarifier. The lower-site work also calls for installing a new odor control system, upgrading an ultraviolet disinfection system, and installing new pumps and other types of equipment.

Additionally, the upper-site project work will involve constructing a new odor-control system, erecting a new electrical building, modifying an existing transfer pump station, and adding retaining walls along a steep bank. The contractor also is expected to construct transmission main manholes, which are concrete vaults leading down to an underground pipe that extends between the two sites.

Separately, Contractors Northwest is wrapping up work on a $2.1 million contract to build a critical care unit at the West Valley Medical Center in Caldwell, Idaho, about 30 miles west of Boise.

The contractor started that project in November with demolition of the interior third-floor space, Taylor says. That project includes construction of new patient rooms, nurses' station, laundry facilities, storage rooms, and reception areas.

In renovating the third floor, the project is expanding the critical care unit from 5,800 square feet to a total of 11,000 square feet. The work is expected to be completed by April.