PRINCE WILLIAM COUNTY — A plan to develop 400 homes and a new mixed-use community on an old dairy farm outside Manassas is moving forward.

The houses would sit on Kline Farm, a 100-acre tract of land in Prince William County that abutts Manassas City, where Prince William Parkway meets Wellington Road and Liberia Avenues. Homes, offices, and retail shops would replace the old grain silos that stand on the property today.

The Prince William County Planning Commission could hear the case as early as October 4. Manasass-based builder Stanley Martin Homes submitted their final proposal documents to the county’s planning office on Wednesday.

Before the homes can be built, a series of land rezonings and special use permits must be approved by the Planning Commission, and ultimately by the Prince William County Board of Supervisors.

For the development to be approved, supervisors would need to amend the county’s comprehensive plan for the area. The current land use of semi-rural residential on half of the property and office and retail on the second half of the land would be changed to “center of community” to allow for a mixed-uses to include homes, office, small retail shops, and restaurants.

The proposal calls for building commercial buildings along Prince William Parkway across from a Harris Teeter grocery store in Manassas City. For these structures, supervisors must also approve multiple special-use permits for a Sheetz gas station, an unnamed drive-through fast food restaurant, a CVS Pharmacy with a drive-through window, and a self-storage facility that would all be built at the site.

“With the number of rezonings and special use permits needed, this is like six projects in one,” said Prince William County Planner Scott Meyer.

Clusters of single-family homes would be built three to an acre on the southern end of the property closest to Buckhall Road, while 265 townhomes with front-loading garages would be erected in the middle of the property.

The development’s proximity to Manassas City is touted in the Stanley Martin’s proposal, noting residents would likely walk to existing shops and grocery stores in the city, and bike to its downtown. Residents would also enter Manassas to commute via Virginia Railway Express and Amtrak trains from the city’s downtown station.

The majority of the new residents, however, are expected to drive, generating some additional 9,000 trips per day on the already heavily congested Route 28, and feeder streets like Liberia Avenue.

Inhabitants of the Kline neighborhood would live in Prince William County, and their children attend county schools. But traffic congestion remains a regional issue, and Manassas officials are closely watching this project.

“Any growth along Route 28, until we do something to relieve traffic congestion, is a tough, tough act,” said Manassas Mayor Hal Parrish II.

Parrish or members of his city council won’t get a say on whether or not the Kline development is approved because it’s a county project that lies just outside the jurisdictional bounds of his city. However, he does support exploring a congestion relief option for Route 28 that involves extending Godwin Drive along the Manassas City and Prince Wiliam County lines across Sudley Road and connecting it to Route 28 near Fairfax County.

The move would relieve pressure on Route 28 closer to Downtown Manassas. A community meeting on the proposal, as well as an option to widen the existing Route 28, or extend Euclid Avenue parallel along the Route 28, will be discussed at a meeting at 7 p.m. Thursday, Sept. 7 at the Manassas Park Community Center.

Back at the Kline property, an unnamed extension of what could be Hastings Drive, from its intersection with Prince William Parkway behind the Harris Teeter, would be built into the neighborhood.

Pedestrian improvements on Prince William Parkway would include a 10-foot-wide shared use path for joggers and bicyclists, constructed by the developer. Bus stops envisioned for local and commuter bus riders on OmniLink and OmniRide buses, respectively, would be built in the center of the property and not be located on Prince William Parkway.

The Kline property would also feature a series of small parks and trails in and around the development. A total of 30% of the property would remain open space.

Meyer said his office is reviewing the proposals and is looking at a total of 136 acres of land — not just the 100 acres on which the Kline property would encompass –to examine how changing the comprehensive plan would affect the mostly rural surrounding areas along Buckhall Road and Lake Jackson Drive.

“Does it make sense to have the center of community land use abuts a rural land use?” said Meyer. “This is one of the things we are looking at.”

The old Kline dairy farm has been defunct since 1989. Drivers on Prince William Parkway passing by its tall silos are reminded time when farming was at the center of life in Manassas when it was a farm town.