VANCOUVER -- The downtown branch of the Vancouver post office has been sold to the British Columbia Investment Management Corporation (bcIMC), one of Canada’s largest institutional investment managers.

No sale price was announced, but real estate sources believe the sale price was in the $130-million range.

The site had been the subject of a claim by several local First Nations, but Jon Hamilton of Canada Post in Ottawa said a “confidential understanding” had been reached with the Musqueam, Squamish and Tsleil-Waututh (Burrard) nations that allows the sale to go through.

The mammoth seven-storey, 686,000 sq. ft. structure was designed by McCarter and Nairne, opened in 1958 and occupies an entire block between Georgia, Dunsmuir, Homer and Hamilton. The post office will move its main processing plant into a new 700,000 sq. ft. facility in Richmond in 2014.

There has been speculation the old post office will be converted to a mall, but bcIMC spokeswoman Gwen-Anne Chittenden said “that’s not correct.”

“Our vision is for a sustainable mixed-use development that will leverage the great transit and the nearby amenities that the site offers,” she said.

Asked what that means, she said “it’s too early to talk about the actual land uses, but we do see there will be mixed land use. The next step of our process is to really go into ... the more detailed planning for the site, working with the city of Vancouver.”

Asked whether the existing building will be retained, she said “the status of the existing building will be considered as part of the whole development planning process. It’s too early to contemplate the plans.”

Heritage expert John Atkin said the “sheer physicality” of the current building means it will likely be retained — and perhaps expanded.

“When it was built, they claimed it was the largest welded-steel structure in the world,” he said.

“In the original architectural drawings McCarter and Nairne had a huge tower off the stump. Budget cuts cut the office tower down, but there were plans for the post office to essentially be a large base for a very tall tower.”

The inside of the building features tall ceilings and large spaces, which offers the new owner plenty of options.

“It’s kind of like Pacific Centre,” Atkin said. “They’re doing the Sears redo for Nordstrom and they’re carving offices out of it and a department store, but no one thought of tearing it down because its square footage is huge.”

BCIMC isn’t a household name, but it quietly invests “more than $95 billion of managed gross assets,” including B.C.’s public-sector pensions.

“Our clients include public-sector pension plans, public trusts and insurance funds,” said Chittenden.

It owns several buildings in Metro Vancouver, including downtown landmarks like Park Place and the Evergreen Building, Willowbrook Shopping Centre in Langley and Broadway Tech, a 1.1-million sq. ft. campus at Broadway and Renfrew. It is currently building 745 Thurlow, a 23-storey office tower on the old Keg site at Thurlow and Alberni.

In addition to its new Richmond facility, Canada Post recently purchased the old Aero Garment block at 333-385 Woodland in East Vancouver for $12,682,500. It’s just east of the Waldorf Hotel.

Ken McGregor, manager of the Musqueam First Nation, declined to go into any specifics about the deal with the post office.

“It is not a land claim, it is an accommodation, and an accommodation has been reached,” he said. “It is confidential. It is not a rights and title case.”

jmackie@vancouversun.com