Developers of Manchester Lakes, a 192-acre commercial and residential community under construction in southeast Fairfax County, lost at least 100 sales during a recent toxic waste scare that virtually halted marketing efforts for more than six weeks.

But now that the county's Department of Environmental Management and Board of Supervisors have accepted reports giving the project a clean bill of health, developers are moving rapidly to regain momentum they say they lost while the cloud of uncertainty hung over the project.

Sales are increasing, and developers are spending advertising dollars. Manchester Lakes promoters this week staged what they called a "reintroduction" of the development, about 14 miles south of the District near Franconia Road. More than 250 real estate agents and brokers showed up to visit models and existing town houses, according to Brian J. McSweeney, whose communications firm represents Manchester Lakes.

"Even some of those agents with bad tastes in their mouths from having lost commissions" on sales that did not go to closing after the toxic threat emerged showed up for the party at Manchester Lakes, McSweeney said.

Next Thursday the Fairfax County Planning Commission will hold public hearings and vote on the final development plan for a portion of the development called the Manchester Lakes Retirement Community. The 27-acre retirement center will be managed by the Fellowship Square Foundation of Reston, well-known in the Washington area for managing senior citizen housing developments and total care facilities.

The Manchester Lakes Retirement Community will include 204 apartments in two five-story buildings, 158 attached housing units and a 170-bed nursing home, according to James L. Brehoney, president of Manchester Lakes.

"We hope the board of supervisors will give it final approval Oct. 29," Brehoney said.

In midsummer, sales virtually halted when the Citizens' Clearinghouse for Hazardous Waste, a citizens watchdog organization, charged that the development was possibly being built on land contaminated with toxic materials. Representatives of the Clearinghouse, developers and county officials waited while four consultants studied the site's water and soil.

Two weeks ago the Fairfax Board of Supervisors accepted results of tests showing that soil and ground water at the construction site apparently were not contaminated with toxic materials. Manchester Lakes representatives had contended the site was safe.

"We are selling again," Brehoney said. Both NVHomes and Pulte, which continued to build while waiting for test results, started to sell town houses again last week, he said.

Last weekend, Brehoney said, "Pulte sold 20 homes , I think, including a lot of come-backs" -- purchasers who had signed contracts to buy town houses before the toxic waste scare but backed off.

"We are all optimistic. We have not done much to negate all the bad publicity," he said. "This community is the safest site in Fairfax County."

Dwight Schar, president of NVHomes, was more direct. "Sure we lost sales, but we kept on building, confident that this thing would work out," he said. "Of course, we had problems. How do you positively promote a project with something like that hanging over your head?

"We tried to get groups of those who had signed contracts organized to try to get facts out," Schar said.

NVHomes model units officially open this weekend, but "80 out of the 200 units are already sold," Schar said. Before the toxic contamination scare, more than 100 were sold.

"We have lost time, but we will make that up," he said. NVHomes usually builds only on a "pre-sell basis." That means construction on a unit does not begin until that unit has been sold.

"Here, we will be able to deliver the product in 60 days. We will be able to get you in there for Christmas," the company president said.

McSweeney predicted a "good month" this October for Manchester Lakes. He said response from brokers this week who still "had bad tastes in their mouth" was good. He said there had been talk about fallout from some of those agents who might not want to sell at Manchester Lakes, but many are coming back.

The applications for final site approval of the units designed to attract senior citizens is seen by many real estate agents as a major statement by the developers of "faith in the safety of their product."

The senior citizens section will create a total care and living environment for many elderly Fairfax residents. The proffers, or offers, in the original rezoning included accepting Medicaid recipients at the nursing home, Brehoney said.

"Ninety of those beds will be made available to residents of the Lee District," the magisterial district of which Manchester Lakes is a part, Brehoney explained. "This gives the community their own nursing home facility," he said.

Prices for town houses in the Manchester Lakes Development now range from the mid-$60,000 range to the low-$100,000 range.