Plans for an $88 million sewer plant on the banks of the Wakarusa River should take a large step forward tonight.

City commissioners at their weekly meeting are scheduled to approve the annexation, zoning and special-use permit for the city-owned facility that is planned on about 540 acres at North 1175 and East 1600 roads.

The project has drawn an official protest petition from neighbors in the area. About a dozen property owners near the site have submitted petitions against the zoning and special-use permit applications. That means city commissioners will have to approve the applications with a supermajority – by at least four votes.

But so far, the five-member commission has been unanimous in its support for the project. The city already has purchased the property, and commissioners have issued debt to fund portions of the project.

The sewer treatment plant is expected to be the largest project ever undertaken by a Douglas County government. Construction could begin later this year, and is expected to last into 2011.

Commissioners meet at 6:35 p.m. today at City Hall, Sixth and Massachusetts streets.