The Washington Suburban Sanitary Commission staff recommended yesterday that one sewage sludge disposal site to serve both Montgomery and Prince George's counties be constructed in a rural region of Montgomery away from densely populated communities.

After receiving the recommendation, a majority of the Montgomery County Council said they would vote for the proposal if Prince George's officials agree to give Montgomery the additional sewage capacity it needs to avert a new sewer moratorium that would stop all development in Montgomery.

"We'll use sludge as a bargaining tool," David Scotton, a Montgomery commissioner to the WSSC, said yesterday following the staff briefing given the county council.

"We'll take the sludge, they'll take the sewage," said council member Rose Crenca after yesterday's meeting.

Montgomery Executive Charles W. Gilchrist also is willing to consider locating a bicounty sludge site in Montgomery, according to Robert Wilson, Montgomery's chief administrative officer who is in charge of the current round of negotiations in the two countries' sewer feud.

Last month, the WSSC informed Montgomery that it had exhausted its share of capacity at the regional Blue Plains sewage treatment plant in the District of Columbia.

Since then, Montgomery officials have been desperately searching for ways to prevent the crisis. Next Wednesday, the WSSC will consider requests from 19 Montgomery Builders for sewer allocations for about 730 new homes under construction-an occasion that could provide the first test of Prince George's willingness to give up some sewer capacity.

Prince George's has enough unused treatment capacity to permit construction of 100,000 new homes. That county's population is expected to grow by 75,000 people in the next 15 years.

Last week, Montgomery Executive Gilchrist renewed the county's request for a "share" of that capacity and announced he would proceed with planning a new $60 million sewage treatment plant in Montgomery as a long-term solution to the region's sewer problems.

As part of the complex sewer debate, the WSSC and Montgomery officials had approved last year a site for composting sludge, the semi-solid residue of the sewage treatment process, in Calverton near the county's eastern border with Prince George's.

However, Prince George's officials, who had agreed on their own site deeper in their county, publicly objected to Montgomery's choice of locations.

At the council's initiative earlier this year the WSSC hired consultants for another study of possible sludge disposal methods and locations. Yesterday, WSSC General Manager Robert McGarry presented the council a new list of 24 possible locations, mostly in rural areas of western Montgomery.

McGarry said the WSSC has determined that constructing and operating the two sites would cost $92 million, a "staggering" sum that he said the WSSC "can't afford."

He urged the council agree to the more "cost-effective" approach of locating one site for both counties in a "remote" section of Montgomery. "The remoter the better," he said.

"I'd be willing to vote for that in return for a reasonable tradeoff," said Council Member Elizabeth Scull reflecting comments of several of her colleagues. "That means that we won't take their sludge for 100 years in return for sewage capacity for just one year, however."