Montgomery County Executive James P. Gleason and the County Council have declared a truce in their five-year-old sewer war.

Gleason has backed away from his firm position that the controversial Dickerson regional plant must be built and agreed to work with the council on developing smaller-scale solutions for Montgomery's sewage-treatment needs.

"We're not going to have one, big monster solution," one of Gleason's planners said. "We're going to have incremental solutions." The County Council is talking the same way.

Gleason's critics on the council have complained in the past - along with the federal Environmental Protection Agency - that Dickerson was too costly and too big.

Gleason said in an interview that the alternatives he and the council will consider will include land treatment. "I feel land treatment would be terrible - it takes too much acreage - but I will recommend it if the public hearing (scheduled for September) supports it," he said.

Land treatment, which EPA is heavily promoting, involves spraying partially treated sewage on farmland or woodland. Most of the remaining pollutants are taken up nutrients by the soil.

"Land treatment of some size is in the county's future," one Montgomery environmental planner said. "Somewhere, we will have to try it - primarily because the EPA is insisting on it."

While environmentalists generally support land treatment because it returns clean water to the land, proposals to bring it to a suburban county like Montgomery are likely to arouse intense opposition from neighborhoods that would be affected by such facilities. Already there have been allegations at public hearings that land treatment is smelly and a health hazard.

While Gleason is retrenching on Dickerson, he said he probably will go forward with an appeal of the recent federal court decision upholding EPA's veto of the project. "But," he said, "If we (Gleason and the County Council) can reach an agreement on alternatives, I will drop the appeal." (On May 19, the County Council urged Gleason to drop the appeal.)

According to new staff figures, Montgomery has about six years before it runs out of sewage treatment capacity. Based on that timetable, the county wouldn't be able to make any more advance allocations by 1982.

Since sewer construction funded by EPA can take more than 6 1/2 years, (counting planning), according to the Washington Suburban Sanitary Commission, Gleason and the council hope to get EPA to approve an accelerated timetable. If that's not possible, they will work on a plan that does not involve federal participation and which would be funded entirely by the county.

Gleason's and the council's decision to work together ends five years of feuding that began when the county executive decided that a big regional facility at Dickerson upcounty was the answer to Montgomery's long-term treatment needs.

With Dickerson's estimated cost mounting and questions being raised about the wisdom of discharging effluent above water intakes, the council urged that alternatives be explored. But Gleason had stood firm.

The recent federal court decision upholding EPA's veto to Dickerson was a blow to Gleason's no-compromise position. He has acknowledged to the council that he doesn't expect an appeal to prevail.

The Gleason-council truce was praised by one of the strongest critics of the Dickerson strategy, council member John Menke. "I think what we're getting is an enormous amount of movement involving the County Council and the county executive - and that hasn't existed over the past five years."

Gleason said that whatever he and the council agree to will go to the public hearing before the November election.

Gleason said he wants an agreement with the council before the November election so voters will know where candidates for executive and council stand on sewage-treatment solutions. Sewer capacity has become perhaps the overriding issue in the county. Without adequate treatment capacity - and that is a question mark beyond 1982 - the county would have to put a moratorium on any kind of significant development, residential or industrial.