The Alexandria City Council is expected to sign off Saturday on a plan for a Potomac Yard fire station that includes affordable housing, a project city planners hail as a new model of public-private partnership in development.

"This will be an innovative mix of uses," said Jeffrey Farner, division chief for development in the city's planning department. "And it is a new way to leverage resources between the city and Potomac Yard."

The council is expected to approve the project's final design and vote on a series of amendments to the area's master plan to permit the fire station, a community facility, to be built on private land. The developers, Potomac Yard Development, plan to donate the land and facility to the city once the fire station is built.

The developers have promised to pay $6 million toward the 24,800-square-foot fire station, the first to be built in the city in more than 30 years. The city would spend an additional $1 million to add a fourth bay at the station to accommodate future growth in the area off Route 1. The building, which would be 70 feet high, would use environmentally friendly, or "green," building materials and be designed for maximum energy efficiency.

The developers also would pay the city $6 million to build 81,000 square feet, or 64 units, of moderately priced housing atop the fire station, which the city plans to leverage, along with $11 million in federal affordable housing tax credits, to cover the $21 million cost of the housing.

The fire station also would have an 800-square-foot room for community meetings and 1,500 square feet for ground-floor retail on the southwest corner.

The apartments in the four stories above the fire station would range from 700 to 1,300 square feet each, with one-, two- and three-bedroom units. Some would have balconies, others private access to a public roof terrace.

The plan calls for 44 of these units to be rented as "affordable" housing, meant for tenants who earn 60 percent of the Washington area's median income, or about $54,000 for a family of four. The remaining 20 units would be set aside as "workforce" housing, designed to recruit and retain public employees such as firefighters and teachers who earn 80 percent of the regional income, or about $72,000 for a family of four.

The goal is that those renting the workforce housing units not pay more than 30 percent of their monthly income on rent. Monthly rents are expected to range from about $1,000 for a one-bedroom to $1,400 for a three-bedroom apartment.

Once the apartments are built, the plan calls for the city to lease or sell them to a nonprofit housing agency to manage.

According to the final design, the fire station's glass bay doors would open onto a green open space that, Farner said, will be a place for people to hang out and help create a sense of community.

The city's Planning Commission unanimously voted to approve the design this month. "Our goal is to have the fire station and affordable housing open by October 2009," said Cathy Puskar, an attorney representing the developers. "Everyone has agreed that this partnership between Potomac Yard and the city is a win-win and is actually going to be the first example of this kind of unique and innovative way to use land throughout the country."

The plan does not come without its critics, however, including Amy Slack, chair of the land-use committee for the Del Ray Citizens' Association, which has argued against the proposal to fill the new fire station with the fire engine and squad now based in their Del Ray neighborhood. They worry that firefighters would no longer be able to respond to emergencies in their community within four minutes, the city standard.

"Our question all along has been, why are you taking something from our community, that builds community, to put it in some other community?" she said. "We don't mind you having it, but why take ours?"

The proposal on the table includes $700,000 to remodel the Del Ray station and a plan to keep a hazardous materials response squad and ambulances there.

The controversy over the fire station began last year when the city's chief code inspector studied the overall design for Potomac Yard, which is intended to be a "city within a city" with townhouses and retail shops set close to the street, similar to Old Town. He worried that ladder trucks would not be able to negotiate the turns onto some of the planned neighborhood's narrow streets and alleyways without having to back up and maneuver, which would cut into response time in an emergency.

It was then that the developers proposed building a fire station in the neighborhood. The Fire Department did its own study of engines, fire stations and response times and determined that the best option would be to move the fire engine from the antiquated Windsor Avenue station in Del Ray.

Residents protested. A task force studied the issue through the summer and ended up agreeing with the Fire Department.

Still, Slack said, she and others say they were promised that the city's decision to build the fire station would be separated from the decision on the future of the Windsor Avenue station. City officials said the future of the fire station will be decided during the coming budget process when they allocate staff and resources.

But that's not the way Fire Chief Gary Mesaris sees it.

"From the Fire Department's stand, it's still the right thing to do," he said. "And from our perspective, it's part of what we're planning to do."

Mesaris said that although no large ladder truck is envisioned for the new Potomac Yard station at this point -- the station will be large enough to accommodate one -- he is confident that the location of the station and the resources there will ensure adequate response times in both the new development and in Del Ray.

"If I thought, in my professional opinion, that response times would be hurt, I would not do it," he said. "This is going to be a noteworthy facility, for the community -- even for the nation."