To get the blessing for large projects in places such as Prince William County, there is an often lengthy process that developers have to go through, which engages residents and, in the end, allows elected officials to decide what’s best for the community.

So, why are residents and activists already concerned about a yet-to-be-introduced proposal for 102 homes off Route 234 in the middle of the county?

A resistant neighborhood and new political realities seem to be colliding, they said.

Much of the proposal, called Mid-County Park and Estate Homes by landowner and developer Mark Granville-Smith, would reside in the county’s Rural Crescent, an 80,000-acre preservation area that was set aside by planners and policymakers in the 1990s.

County planners and advocates want to preserve the rural beauty and encourage redevelopment elsewhere.

That’s why some nearby residents, who are also concerned about issues such as traffic, are mounting an early effort to squash the project.

On Tuesday, the Board of County Supervisors is expected to decide whether to “initiate” a change to the county’s long-term planning document. The preliminary step means that county officials, along with the developer, further examine the plan and produce studies about traffic and ecological effects, among other issues. County officials and an advisory board study the proposal before it’s sent to supervisors for a final decision.

The proposal for 102 homes on 335 acres doesn’t make sense, said Gary O’Brien, president of the Landview Estates Civic Association, a nearby neighborhood. He said many homeowners bought in the area because their properties back up to Rural Crescent land, which is supposed to remain open space.

“We bought out here to get away from it all, and we paid a pretty premium to get it,” O’Brien said. “Now, he wants to destroy all that.”

O’Brien also said neighbors worry about more traffic on congested Route 234.

Granville-Smith said the project is different from those he has proposed in the past. In 2006, supervisors deferred a plan to reexamine whether 8,400 acres of nearby land should remain in the rural area. In 2009, supervisors rejected a plan for a similar number of homes on the land.

The homes, Granville-Smith said, would be placed on one portion of the property, and two-thirds of the acreage would be preserved as a park, turned over to the county and opened to the public. The park would be preserved as wooded area and also preserve 1.6 miles of stream.

Under existing zoning rules, Granville-Smith can build one house per 10 acres. The 30 homes that would be built — if his proposal is not accepted — would be spread out, hurting the environment, and neighbors would probably want to hunt and use four-wheelers on their rural properties, he said.

Neighbors probably wouldn’t want that, he said, whereas his proposal fits in well with the surrounding community.

Granville-Smith also said that his latest proposal would use the most environmentally sensitive techniques — such as a type of sewer system that requires less land be affected — that wouldn’t be required under existing rules.

“It’s probably one of the most environmentally sensitive developments in the last 10 years in this county,” he said. “It could be the premier executive community . . . from an environmental protection standpoint. Nobody talks about the benefits the county is getting.”

Board Chairman Corey A. Stewart (R-At Large) said his initial reaction to the project was positive. “These are . . . very nice single-family home lots with a large amount of open space preserved throughout the development,” Stewart said. “To me, it’s just common sense.”

Elena Schlossberg-Kunkel, who leads Advocates for the Rural Crescent, said developers have argued for other projects approved because of “unique” circumstances such as religion. “What’s unique about this piece of land is nothing,” she said.

Schlossberg-Kunkel also said that new Supervisor Peter K. Candland (R-Gainesville) is untested on Rural Crescent issues. John Stirrup, Candland’s predecessor, was a reliable advocate for the Rural Crescent, she said. She worries whether that means developers will have opportunities in the county’s rural area with Candland on the board.

Candland has said that he supports preserving the Rural Crescent, but during the recent campaign he declined to sign a pledge saying he would do so, which worried some voters and advocates.

“I’ve always supported the Rural Crescent, and as such, I’ll scrutinize this project very closely,” Candland said in an e-mail.