The Provo City Council took its first official look at a proposed 20,000-seat open-air music venue near the base of Provo Canyon — and members had a lot of questions for the developers.

At a meeting Tuesday, council members made clear their hesitation to move forward without more data on the Vesper Amphitheater project, first announced in May by David Osmond, a member of Utah’s famed Osmond family.

The amphitheater, if completed, could be home to major concerts and other live events, with a seating capacity equal to that of the Delta Center in downtown Salt Lake City.

The amphitheater project is being spearheaded by David Osmond, son of the late Alan Osmond of the singing brothers, and David’s uncle, Las Vegas showman Donny Osmond.

No public comment was scheduled at Tuesday’s meeting. The council has not set a vote on the Vesper proposal; the earliest a vote could happen is Aug. 25, though the city said a decision may be delayed until September.

Council member Katrice MacKay said that the developers haven’t provided “enough numbers” to ensure the project’s safety, or enough information about how much Provo residents will have to pay to build and maintain the venue — either through the city, Utah County or the Utah Department of Transportation.

Developers have not said how much it would cost to build the amphitheater. They have said some of the cost would be paid through private donations.

“All these things, supposedly you’re going to be paying for all of them, which seems infeasible,” MacKay told Vesper’s project manager, Bryan Bayles. “We need a better idea from UDOT exactly how much these things are going to cost.”

Council member Rachel Whipple had questions about a “conservation easement” mentioned in the proposed development agreement with Provo, meant to limit development and protect land around the venue for agriculture, wildlife or historical purposes.

Vesper asked to acquire two adjacent parcels of land from the city, totaling about 100 acres. About 60 acres of that space, the proposed agreement says, would be put in the easement and left largely undeveloped.

Whipple said she wants to see a binding commitment in the development agreement to guarantee no further commercial or residential activities on those parcels. She also wants assurances the public would still have access to trails in that area.

“I would want this area to be very strictly bounded so that the concerns of commercial creep would be addressed,” Whipple said.

Bayles, in his presentation to the council, also talked about some additions to the project, made since he spoke to the Provo Planning Commission in June. The commission voted down Vesper’s request for a zoning change and approval of the concept plan.

Bayles said Vesper has been working closely with UDOT to alleviate concerns about canyon traffic. He also showed some new renderings for the amphitheater, including a plan to construct an overpass across Highway 189 to allow visitors to exit the site on a right turn.

“As you’ll notice, a lot of the structures and facilities don’t change that much,” Bayles said. “The change has been in the site plan to really accommodate traffic and access to the site.”

He also reminded council members that Vesper is attempting to reclaim and “improve a disturbed property, rather than develop a pristine canyon landscape.”