During five decades of tumultuous growth and rapid urbanization, the 93-acre diamond-shaped swath of hills and trees on the northern edge of Manassas remained an untouched jewel. For the last several years, the parcel has been the site of expectation and anticipation, what was to become the city's final installment in major residential development.

The waiting, it appears, is about to end.

With the announcement last week that a developer has a contract to buy the pristine "Smitherwood" acreage in the hope of building a residential community there, Manassas officials have begun to plan for what will likely be the last large-scale residential project in the city. There will be much discussion about the size and type of development that will be allowed on the land, which is currently zoned agricultural.

The Airston Group, a Gainesville development company that focuses its efforts in Prince William County and Northern Virginia, announced Thursday that it had reached a purchase agreement with Selwyn and Virginia Smith to purchase the 93 acres.

Although no terms of the agreement have been released, the deal is likely worth several million dollars. Some have speculated that the land was worth more than $10 million at the height of the real estate boom in the late 1980s but that price has likely dropped significantly since then.

The deal is contingent on zoning approvals and a city go-ahead, a course of action that Manassas officials say they won't take lightly. City officials have expressed excitement over the deal but also have made it clear that certain elements must exist for a community to develop. Those include: The development must be unintrusive, innovative, unusual and one that will lure a new crop of upscale residents to Manassas.

"We want some high-end housing for corporate owners and presidents, the type of housing for people who want to move out into Manassas and up in quality," said Roger Snyder, the city's director of community development. "It's a milestone in that the 90 acres is by far the largest piece left and that everything after this will be small. That's why we want this to be done right."

Snyder said the planned community for the property would have 270 to 300 units, most of which would be single-family houses designed for an upscale clientele, with a host of custom homes boasting original designs. He said there likely would be a man-made lake and a significant buffer zone of trees and greenery to allow the surrounding neighborhoods to maintain their woodsy atmosphere.

"The Airston Group does not want to cut up the land in a cookie-cutter fashion," Carlos G. Vasquez, the project's architect, said in a statement released Thursday. "They are serious about creating a special project that they, the city and the residents will be proud of."

City officials are clear about their desires because they have been planning for at least 10 years to make such a community happen -- from infrastructure design around the property to general urban planning issues such as traffic and schools, said Public Works Director Michael C. Moon.

The two major concerns, city officials said, are transportation and education. The new community is estimated to generate an additional 3,000 car trips each day and incorporate hundreds of additional school-age children.

City officials boast that the community would be self-contained, with one entrance on Plantation Road, and thus the strain on neighboring streets would be diminished. Snyder said the developer, not the city, would be responsible for widening Plantation and possibly creating turn lanes at the Route 234 intersection.

City staff plans to meet at the beginning of July to discuss various infrastructure issues. The discussions will include how Manassas would handle an influx of children: send them to several existing schools, or build more?

Moon said that much of the infrastructure questions already have been answered through years of planning and that the addition of a new neighborhood won't be nearly as traumatic as when the Wellington community gobbled up a huge chunk in the southern part of the city and added thousands of residents.

"If we could deal with a Wellington in this city, we can deal with this project," Moon said. "This is about one-eighth the size, and we've been expecting it for a long time. After all of the planning and debating, it's good to finally see it happen."

But there is a blemish on the diamond. By all accounts, an additional residential community would only increase the city's tax burden. Although industrial development pays the bills, residential development almost always ends up pulling money out of the coffers, mainly because of educational costs.

Snyder said city officials had never intended for the land to be used for commercial development and thus expected such a burden at some point.

The additional 1,000 or so residents would bring the city one step closer to its inevitable population plateau. Current estimates predict that within 10 to 15 years, Manassas's population will level off at 40,000 residents. Anticipating little growth, the city does not have to worry about a swelling residential tax burden because the current population is already at 35,000.

"I have spoken about impacts of future growth before, and I had this parcel in mind," said City Council member Harry J. "Hal" Parrish II (R). "We've been very much aware that the business climate in Manassas is very helpful to economic development.

"By and large, as we all know, homes don't pay the amount of taxes that are used. We all go through that, and we all need to provide the solutions for that," he said.

The next step, Parrish said, is for the whole plan to go through a process of scrutiny, where zoning and planning officials will make sure the project is what both Manassas and the developer are looking for.

Parrish said that he is sure the project "will get a lot of attention in the not-so-distant [future]" and that he thinks it could be "very good" for the city. Manassas officials have estimated that residents could be moving within three years.

Mayor Marvin L. Gillum (R) said the project is a major one for several reasons.

"It's the last important parcel of land that we have in our city, and we will be very careful about what we allow on that property," said Gillum, adding that he, too, will be keeping an eye on it.

"It's exciting, and I hope it turns into a nice community out there," he said. "It's an exciting event for the city."