The Seattle Art Museum is going ahead with a ceremonial groundbreaking for its new Olympic Sculpture Park next Monday, even though questions remain over the fate of Metro's trolley line and waterfront maintenance facility, located on a prime part of the park property.

Consultants hired by Metro and the Port of Seattle are analyzing costs and other issues related to extending the trolley line about a mile north and relocating the barn at a new, northern terminus.

The existing maintenance barn would be razed if the museum completes the $85 million sculpture park as architects have designed it. The museum hopes to open the park — a green space with an indoor pavilion and outdoor art — in summer 2006.

The park possesses a commanding view of Elliott Bay and the Olympic Mountains except for the unsightly barn, which is fundamental to the streetcar's operation because it is where the vintage fleet is serviced and stored. The barn sits on the lower, 2.5-acre portion of the sculpture park's sloping 8.5 acres, closest to the shoreline.

Port Commissioner and City Council candidate Paige Miller initiated the idea of extending the line north as a way to both rescue the trolley and build the park the way it was intended. In April, Miller imposed a deadline of June 1 for local officials to resolve several issues, such as setting a timeline and determining how much it would cost to tear down the barn, build a new one, relocate existing utilities and build a new substation.

But Port spokesman David Schaefer said a detailed plan won't be unveiled for at least another couple of weeks.

Once costs are determined, the overriding issue will be how they will be apportioned among stakeholders. King County (which operates Metro), the city and Port would share the burden, with the museum possibly pitching in to pay for tearing down the barn.

"Everyone is waiting to find out what are the things that need to be done and who is going to pay for them," Schaefer said.

County Executive Ron Sims and Mayor Greg Nickels are on record supporting the trolley service and the sculpture park. But the county or city still could balk on a northern extension if its share proves too costly. County Councilman Dwight Pelz, who is running against Miller for the City Council, has estimated the county share could range from $5.5 million, which he considers acceptable, to $9.4 million, which he calls unreasonable.

Miller has said the Port is committed, no matter its share of the cost. The Port has offered to donate the land for the barn and to come up with financing for the new track and two new stations, whether the money would come directly from Port funds or from private sources that would benefit from the line extension.

As conceived, the new track would run within Port and city park land, parallel to the Elliott Avenue West business district, and end near the Amgen campus. Port officials have asked BNSF Railway officials about the possibility of laying new track for the trolley within its railroad right of way, which could reduce costs.

Original construction plans for the sculpture park called for tearing down the maintenance facility in September.

Local officials still could ask the museum to delay the construction phase of the park nearest the shoreline, leaving the current barn standing so the trolley can continue to operate until a new barn is built. It is doubtful that one mile of new track could be laid and a barn built before the park's opening next year.

Chris Rogers, museum director of capital projects, said it makes sense to proceed with next Monday's groundbreaking event, which already has more than 250 RSVPs, even though the future of the barn is not known.

"The uncertainty relates to 30 percent of the site," he said. "The other portion is ready to go."

The project includes stabilizing the section of the Elliott Bay seawall that runs along the park and creating a small sand beach within Myrtle Edwards Park.

Rogers said no conclusion has been reached as to whether the museum could rebuild the crumbling seawall with the barn still standing. Environmental regulations allow construction within the bay only from November through February, when fish are not migrating. If the existence of the barn stops the work from taking place over the winter, seawall reconstruction would be delayed until at least the following winter, after the sculpture park is scheduled to open.

Stuart Eskenazi: 206-464-2293 or seskenazi@seattletimes.com