Portland's economic development agency picked a Colorado firm to assist in planning for the soon-to-be-vacated downtown post office blocks, one of the largest development opportunities in the city center.

The board of Prosper Portland picked Denver-based Continuum to undertake the planning effort, which includes the 14-acre post office site near the west end of the Broadway Bridge and surrounding city-owned properties. The adjacent sites bring the project area to a total of 32 acres.

As the chosen developer, Continuum would advise the city on how to develop the site being vacated by the U.S. Postal Service, which is moving its operations to a site near the Portland International Airport, as well as the adjacent sites that include the west end of the Broadway Bridge, Union Station and the Greyhound bus terminal.

The development firm won't be paid for its advisory work, but it will get the first chance to buy the post office site from the city and pursue the development once the plan is complete. The sale of the land will pay back the $88 million the city spent to buy the site from the Postal Service.

The agency also selected Portland-based ZGF Architects to complete the master plan, an effort for which it will be paid up to $2.1 million.

Continuum has undertaken similar projects in its hometown. It was the master developer for Denver Union Station, a 10-acre redevelopment of former rail yards. It's nearing completion of the redevelopment of the 26-acre site of the former University of Colorado Health Sciences Center.

It was the only of the three finalist applicants who hadn't partnered with local firms or individuals, but Prosper Portland officials said the firm had committed to including locals in its team if selected.

The redevelopment effort is expected to include more than 500 units of public housing developed by the Portland Housing Bureau plus nearly 2,000 units of privately-developed housing, 10 percent of them with rent restrictions for low-income households.

-- Elliot Njus

enjus@oregonian.com

503-294-5034

@enjus