The saga of Chiles Tract, one of the longest-running discussions in Fairfax County, appears to be heading for a conclusion, at long last.

The issue was once again before the county Board of Supervisors Monday, and while it looked as if the supervisors might be writing another long-winded chapter to the story, they apparently are prepared to make a final decision on the complicated and controversial issue at their next meeting Monday.

And there were solid indications at the meeting this week that the supervisors are prepared to give the developers the zoning densities they want, but with enough built-in controls to prevent citizens from shouting, in unison, "Sellout!"

What to do with the Chiles Tract, the county's last piece of prime undeveloped land on the Beltway, has been debated by the supervisors, citizens and developers since 1975.

Neighboring residents who have long benefited from the tranquility of the undeveloped tract want as little development as possible, while developers are bargaining for high density zoning. And the supervisors seem to want just as little and just as much to satisfy both sides.

The Chiles Tract is actually two holdings -- 155 acres in the northeast corner of the Beltway and Rte. 50, and 179 acres in the southeast corner. Costain Washington Inc., a Canadian-controlled development firm that has a contract to buy the northeast parcel, and Cadillac Fairview, another Canadian development firm that owns the other parcel, have joined forces in offering $18 million in road improvements as well as other public goodies to make their rezoning proposals palatable.

Costain has proposed construction of 1.7 million square feet of office space, 450 houses and apartments and 50,000 square feet of commercial space. Fairview has proposed 1.9 million square feet of office space, a 500-room hotel, 690 houses and apartments and 50,000 square feet of retail space.

The total office space would, as one apprehensive citizen noted, be the equivalent of "24 Massey Buildings." The 12-story Massey Building in Fairfax City is Fairfax County's administrative headquarters.

In addition to making $18 million worth of highway improvements, which would include a Rte. 50 overpass, Costain and Fairview have promised to set up an extensive car- and van-pooling program to reduce the impact of their developments on the already overburdened roads straddling the Chiles Tract.

They say that while their developments eventually would employ 11,000 persons, ride-sharing and other transit systems such as shuttle and regular bus service would reduce traffic from 9,700 trips a day to about 4,500.

In an 11th-hour offer that appeared to sway some of the supervisors, Costain and Fairview said that if ride-sharing wasn't successful in reducing traffic, they would stop building at the 3-million-square-foot mark for up to two years.

Last Monday's hearing produced a sight seldom seen in Fairfax -- two of the county's most formidable zoning attorneys talking opposite sides.

On one side was John T. Hazel Jr., attorney for Costain, who, in defending the densities proposed by his client, said the total development would provide Fairfax with annual net revenues of $7 million, while conventional development would mean no surplus whatsoever.

On the other side was Edgar A. Prichard, attorney for the Melpar Corp. adjacent to the Costain site, saying "We most strenuously oppose the (high) densities."