In an effort to dispose of its sewage neatly, efficiently, organically and cheaply, Montgomery County will turn it into soil conditioner.

Controvery erupted at public hearings last week over the five proposed composting sites, all lying along the border between Montgomery and Prince George's Counties. Residents in the areas of the sites protested that the composting facility would produce foul smells and potentially harmful bacteria.

The Montgomery County Council is expected to decide by the end of this month which of the five sites will hold the facility. The Washington Suburban Sanitary Commission must have the decision by that time to get the site ready for use by next July, when the county will run out of places to put its sewage, said Dave Sobers, director of environmental planning for the country.

For three years Montgomery County and Prince George's County have taken turns disposing of what is now 600 tons a day of sludge - treated sewage from which solids have been removed - produced at the Blue Plains sewage treatment plant near I 295.

Currently, Montgomery County puts it in 30-foot deep trenches on a site at New Hampshire and Ednor Road in the county at a cost of approximately $50 a ton, said Sobers.

The county will use up the capacity for trenching at the site by December of this year, the agreement between the two counties to take sludge will technically end at that time as well.

According to Donald Vogt, WSSC project manager for the composting facility, Prince George's and Montgomery officials have reached a "gentleman's agreement" under which Prince George's County will trench sludge for both jurisdictions in Cheltenham until the capacity of the site is exhausted in July of 1978.

Based on the success of an experimental composting facility in Beltsville, run by the United States Department of Agriculture, the county council and county executive James P. Gleason recommended using a compost facility for its share of sludge as an amendment to county and WSSC sewerage management plans.

In composting, which Sobers says will cost about $14 to $17 a ton, a 14-foot-long, 80-foot-wide layer of sludge is mixed with wood chips. Sludge produces the foul smell, so the layer is covered with a blanket of already composted non-smelling material that insulates the sludge.

The sludge and wood chips mixture are aerated through covered pipes, and the air keeps tiny air-breathing or aerobic bacteria in the sluge alive, said Vogt. These bacteria generate so much heat that the temperature inside the pile reaches 150 to 170 degrees Fahrenheit. The intense heat dries moisture in the pile and kills off the aerobic bacteria plus any viral germs in the sludge. After 21 days, the mixture is set aside for 30 more days, and the result is a humous, unobjectionable smelling compost that can be used as soil conditioner, according to Vogt.

The resulting soil conditioner "fluffs up the soil. It holds water better so you don't have to water your grass so much," said Louis Peltier, an environmental planner.

"We'll have no problem in getting rid of it, but I don't know if we'll make any money on it," said Peltier. He added that the county has no plans yet for giving away or selling the soil conditioner.

In April, the county asked WSSC to select suitable sites, and they proposed five near industrial parks and what they have defined as low density residential areas near Rt. 29 between New Hampshire Avenue and Sandy Spring Road.

Citizens in those areas protested at the public hearing however, that the proximity of the sites to their homes would prove smelly and unhealthy.

"It's patently unfair for one community to receive all of the sludge from Montgomery County," said Margaret Hardy at the public hearing.

Hardy, a spokeswoman for the Calverton subdivision near the sites, scoffed at the designation "low density." She said that her community contained 1,500 single-family homes and had projected 1,000 families for the planned Calverton apartment complex.

"An eventual 800-ton a day opeation has potential for emissions of fungi that are of concern to the aged, the infirm, and the allergic," Hardy added. Another problem she noted was the future of the housing in the area. "The value of property will go down," she said.

"Sewage areas are usually associated with slum areas and builders may be reluctant to build here," Carrie Lusby testified about her Briggs Chaney Road area where another proposed site is located.

WSSC spokesman and agriculture officials claimed the smells and health hazards are minimal.

"The process of composting is designed to control odors to as low a level as possible," said Department of Agriculture official Eliot Epstein at the hearing. "The odor is musky and woody, resulting from the decay of organic materials."

The germs in the material that worry residents are the germs that may escape into the air as the sludge is being poured into layers, not as the actual composting is taking place, engineer Vogt explained later. Those are pathogenic materials like germs, bacteria, worms carrying diseases such as typhoid, Vogt said.