After 15 years of work, the Land Conservancy of San Luis Obispo County has the authorization it needs to transform the historical Octagon Barn into an agricultural museum and event center.

The county Planning Commission approved the project Thursday. An appeal of the project to the Board of Supervisors is unlikely because no one spoke in opposition to it Thursday.

The project will be built in phases over the next decade or so. When complete, the barn and surrounding 6.25 acres will serve as a trailhead for the Bob Jones City to the Sea Trail, a community meeting place and a monument to the county’s agricultural heritage.

Commissioner Carlyn Christianson described the facility as a “very unique project.” Initially, she had concerns about parking and traffic, but she said those have been addressed.

The other commissioners were also supportive of the project but had lingering questions about noise, the number of events that would be held there annually and other issues. The facility could host as many as 300 events a year — 100 large events and 200 smaller gatherings.

“These loose ends can come back and bite a project in the end,” Commissioner Ken Topping said. “We don’t want to love it to the point it goes out the door without asking the appropriate questions.”

The 112-year-old barn, on South Higuera Street just south of San Luis Obispo, was on the verge of collapse when the Land Conservancy began restoring it in 1997. That restoration is complete, and the group is moving on to other structures on the site, including a milking parlor.

Speakers from diverse groups including bicyclists, farmers, regional planners and the San Luis Obispo Film Festival spoke in favor of the project. Bob Hill, the Land Conservancy’s executive director, said the barn facility is intended to be a bridge between urban and rural parts of the county.