The Duluth Planning Commission on Tuesday signed off on plans for a Costco store at the corner of West Arrowhead Road and Haines Road.

The plans, from Illinois-based developer TJ Design Strategies, call for a 161,225-square-foot retail warehouse and a 747-stall parking lot on almost 21 acres of a 56-acre site.

With the commission's approval, work on the project could begin within one year, but the developer could request up to a yearlong extension.

During Tuesday's meeting, nearby residents and business owners expressed concern that traffic would worsen on already busy streets.

Adam Fulton, Duluth's interim director of planning and development, said that while both Haines and Arrowhead roads are county highways and outside the city's jurisdiction, city staff is working with St. Louis County to widen the roads and add turn lanes. Haines Road already has a public sidewalk and Costco plans on building a public sidewalk on Arrowhead Road along its property. Additionally, a traffic signal is planned for Costco's easternmost access to Arrowhead Road.

The commission unanimously approved the mixed use-commercial planning review of Costco.

Earlier in the meeting, the planning commission approved the preliminary plat of the 56-acre site with a 6-1 vote with commissioner Tim Meyer voting no.

Meyer said he had a hard time approving it without knowing if there would be plans for future development on the property's other 34 acres.

"I guess I have a little bit of trouble approving the plat without having an idea of what the intent to build on the remainder of the property is," Meyer said.

Fulton said that the developer has not said it would build anything on land it would own to the north and east of the planned Costco, in part because much of that area is wetlands. He also said any future development on that site would have to go back in front of the commission.

"While the developer has not indicated with any level of definition what the plan is for the parcels to the east, they have indicated that there are significant development limitations because there are substantial wetlands in that area of the plat," Fulton said.