A slowly unfolding vision for the transformation of the former Twin Cities Army Ammunition Plant (TCAAP) in Arden Hills is coming into sharper focus, with a mix of new neighborhoods, businesses and parks on the horizon.

A draft master plan which, when finalized next fall, will become the guidebook for how development of the 427-acre tract at the junction of Interstate 35W and Hwy. 10 will proceed was reviewed last week by the Arden Hills City Council and the Ramsey County Board. It also will set the zoning rules for the new development, said Jill Hutmacher, community development director for Arden Hills.

The draft master plan will get further scrutiny early next month by the TCAAP Joint Development Authority Board, comprising city and county officials, and at a public open house on Jan. 22.

After public comments are gathered, the Arden Hills City Council is planning a vote in February or March on whether to proceed with the plan.

Very much in the embryonic stage, design concepts presented by the Minneapolis architectural firm ­Cuningham Group envision a brand-new community within Arden Hills that employs 4,000 people and also holds 1,700 housing units where 4,000 people will live.

It envisions 2 million square feet of office space and 300,000 square feet of retail space (to compare, a football field is 57,600 square feet). The land use breaks down to 168 acres for ­housing, 156 acres for offices, 18 acres for retail, 13 acres of mixed uses and 53 acres of open space (an acre is slightly smaller than a football field).

The site comprises two chunks: a larger main portion that bends along the east side of Hwy. 10 to Hwy. 96, and a 47-acre piece connected to it referred to as the “thumb” in the northwest corner. The latter portion, which is flat, is isolated from the main chunk and overlooks Rice Creek near Rice Creek Regional Park, is best-suited for one special, single, as-yet-unknown use with a single owner, the plans show.

It also envisions three distinct residential neighborhoods with different types of housing offerings, interspersed with plenty of green space. The designs for the neighborhoods are intended to blend with the character of neighborhoods already in Arden Hills, with views to wetlands, lakes and woods.

Residents would be able to walk to shops and workplaces, meaning people could live and work within the community, and it would have easy access to trails.

“I’m very happy with the progress that has been made, and the recommendations that are coming forward,” said Ramsey County Board Chairman Rafael Ortega. He said the plan has a good mix of ­commercial areas, light industry and different types of residential offerings that meet the goal of creating jobs and bringing vitality to a long-neglected piece of land. And the plans have come together quickly.

“It’s hard to believe we just purchased this site a year ago,” Ortega said. “I’m already ­sitting down with developers and investment folks who are very interested in coming to TCAAP.”

Development of the site represents a once-in-a-lifetime opportunity, said Jonathan Weinhagen, regional director of the St. Paul Area Chamber of Commerce. The chamber and the county have formed a partnership group to support planning for the site’s ­redevelopment.

“It’s really a consequential development for Ramsey County, and the rejuvenation, if done right, will become an economic driver for decades,” he said.

In particular, he added, the early design concept has a mix of housing that includes features that resonate with Generation Y, an often overlooked population — generally the children/grandchildren of baby boomers — when it comes to community planning.

“Gen Y has different ideas of what housing should look like,” he said. “They like low-maintenance — they don’t want to take care of big yards, so they want smaller lots and higher density of housing.”

The early concept would allow younger people to cycle through different types of housing as their needs change. Access to public transit, including plans to extend Snelling Avenue’s bus-rapid-transit line that starts in 2015, also holds appeal, Weinhagen said.

The government-owned, contractor-operated TCAAP was built in 1941 at the outbreak of World War II. Ramsey County bought the site, with its heavily contaminated soil, for $28.5 million.

Nearly all of the buildings of the once-sprawling complex have been demolished, and the soil remediation is expected to be done in mid-2015.