The intersection is expected to remain closed until about Thanksgiving.

The City Council on Monday hired Castor Construction, of Fort Dodge, to do the work at a cost of $3,007,008.21.

The city has a $2 million state grant to help pay for the job. The rest of the money will come from the city’s 1-cent local options sales tax.

The plan calls for a left turn lane, a right turn lane and a lane for traffic going straight ahead on all four sides of the intersection.

Chad Schaeffer, the city’s chief development officer, said the work will begin July 27.

He said on that day, the entire intersection will be closed. The first steps, he said, will be to tear up all the existing concrete and to demolish the former Sinclair station on the southwest side of the intersection.

According to Schaeffer, the work will be mostly complete by the end of November. He said new traffic signals will be placed at the intersection in the spring of 2027. At the same time, new traffic signals will be placed at the intersections of North 15th Street and Sixth Avenue North and North 15th Street and Seventh Avenue North.

North and south traffic will be detoured to Ninth and 12th streets. Schaeffer said the portion of North Ninth Street that is now closed will be reopened this week. It will be closed again for about two days next week for repaving, but will be fully open by the time the intersection is closed.

East and west traffic will be detoured onto First Avenue North and Central Avenue.

Other bidders for the intersection job were Rasch Construction, of Fort Dodge, $3,222,347.19; Concrete Technologies Inc., Grimes, $3,227,321.27; Reilly Construction, Ossian, $3,231,739.03; and Hulstein Excavating LLC, Edgerton, Minnesota, $3,266,490.21.