The Prince William Board of Supervisors recently approved the first residential development that sets aside some dwelling units for affordable housing.

Sami Totah, president of Tri-Land Inc., agreed to reserve 10 percent of the 3,655 planned residences in the Villages at Saybrooke for sale to families who earn 75 to 80 percent of county's median income of $50,434.

Located near the county's planned industrial and commercial center on Linton Hall Road, the 1,123-acre project is expected to house 11,600 people when it is completed. That makes it one of the county's largest developments and Tri-Land's largest project.

The supervisors approved the project unanimously late last month and praised Totah for bringing housing to an area near the planned employment center. They urged other developers to consider similar affordable housing projects.

Supervisor William J. Becker (R-Brentsville), who represents the area, said, "We need {Saybrooke} to support the industrial area. We didn't have any low-cost or reasonable-cost housing nearby."

The project is less than a mile from the 971-acre Broadview Center commercial and industrial park, which the board approved in September.

A county housing task force reported last year that 30 percent of the families who live in Prince William cannot afford to buy a house there.

The approval comes as the county staff begins drafting an ordinance on affordable dwellings that could allow developers to build extra houses on their property, provided they reserve some of the housing for low-income families.

Saybrooke's affordable units will include town houses and condominium apartments sprinkled throughout the development. The less expensive homes will not look any different on the outside than the others, said Tri-Land's attorney, Michael D. Lubeley.

The developer can afford to sell the houses at a lower price because "you have the rest of the development absorbing a large part of the infrastructure costs," including a $3 million bridge over Broad Run for Sudley Manor Drive, Lubeley said.

The project called for significantly more units than the county's current comprehensive plan would have permited. The comprehensive plan serves as a guide for development.

But a county staff report found that a "planned . . . community could be an appropriate transitional land use between suburban development to the north and west and the agricultural areas of Vint Hill and Nokesville."

In addition, the supervisors are expected to adopt a new comprehensive plan next week that recommends one to four dwelling units an acre for the area. Saybrooke's overall density is 4.7 units per buildable acre, or 3.3 per acre if unuseable flood plain land is included.

The developer also agreed to build the less dense parts of his project, such as single-family houses, school sites and a church site, on the exterior parts of the project, to minimize the effect on less dense neighboring properties.

Totah, who is based in Hyattsville, said he plans to file his first site plan for the project in six to nine months. From then on, "the economy will direct the pace of development," Totah said.

"We have the financing needed for now . . . . We need more {money} to put in roads, {but} by that time the economy will have improved," Totah said. Tri-Land, which specializes in residential development, built the 300-unit Potomac Crossing in Montgomery, and two 400-unit projects in Prince George's.

The Saybrooke proffers also include land for two schools, a fire station, a library, a police substation and a commuter parking lot. In addition, 70 acres of the flood plain part of the land has been set aside as part of a linear park along Broad Run.