They are nothing more than mounds of earth, often camouflaged by grass. But in the fight to stave off suburban sprawl in northwestern Montgomery County, sand mounds have taken on unusual prominence.

Twenty-five years ago, county planners created one of the nation's most ambitious land preservation programs, setting aside 93,000 acres for farmland and open space. To deter residential development, they kept public water and sewer service out of most of this agricultural reserve, forcing property owners to use wells for water and septic systems to filter sewage into the ground for absorption.

Back then, the planners knew that sewage would not drain well in much of the clay-like dirt, making large chunks of land unsuitable for traditional septic systems and for development. As is often the case, however, technology has caught up with them -- in the form of sand mounds.

The mechanics of sewage disposal are well-known to residents of Montgomery's "upcounty." In a conventional septic system, waste flows into a storage tank, then into a drain field where the soil soaks up most of it. In a sand mound system, a pump carries the sewage up into a man-made mound of sand and gravel, bypassing the unsuitable soil. A pipeline then lets the waste drain down through the soil.

Sand mounds are "a cheat in terms of the intent and the spirit of the ag reserve," said Larry Schaudies, a horse farmer near Poolesville.

Last week, two County Council members took on the sand mounds, proposing a six- to nine-month moratorium on the building of such systems while the county decides how, or whether, to regulate them. The council will hold a public hearing on the proposal tomorrow.

Schaudies has a vested interest in the outcome. His farm sits next to 704 acres of hills, wetlands, streams and forest. Not long ago, soybeans and corn grew there, he said. This year, the county's Planning Board gave preliminary approval for a Bethesda-based developer to build 15 single-family homes on the property; most would rely on sand mounds for sewage disposal.

"They're ruining the land for agriculture," Schaudies said on a recent afternoon, a faded John Deere cap covering his long, gray hair.

Many other farmers, developers and some county officials believe that to be an overreaction, considering that just 37 sand mounds have been approved in the vast reserve since 1999. "I don't see where the crisis is," said Wade Butler, co-owner of Butler's Orchard in Germantown.

As the county celebrates the 25th anniversary of the agricultural reserve this year, its leaders face a number of potential showdowns between preservation and development. A council vote to limit the ability of churches to build large complexes in the reserve is expected this month. The Planning Board, meanwhile, is trying to determine whether some farmers have sold for profit houses that they were allowed to build specifically for their children's use.

"The concern about the ag reserve is the proverbial death by a thousand cuts," said Council President Tom Perez (D-Silver Spring), who is sponsoring the sand mound proposal. "There's no one, specific initiative that ends up eating into the agricultural reserve. But little by little, it becomes like Pac-Man . . . potentially eating its way into the commitment of the ag reserve."

A Shield From Sprawl

County leaders have touted the reserve as a national model, proof that a local government can protect a large swath of land from suburban invasion. Despite a housing shortage throughout the county, the council has restricted development in the reserve to one house per 25 acres.

"The agricultural reserve is our Central Park," Planning Board Chairman Derick Berlage said. "It is a great oasis surrounded on all sides by urbanization."

But it is far from a preservationist's dream: From 1997 to 2002, the amount of farmland in the county dropped from 77,266 to 75,077 acres, according to last year's census figures. County officials expect it to shrink to 70,000 acres by 2010.

"I want to live here instead of Fairfax because I don't want my county paved over," Perez said. "The challenge is: How do we continue to preserve that in the face of demographic changes and an array of pressures to develop? That is going to be one of the paramount public policy challenges before the council over the course of the decade."

In many cases, the county's policies and practices have opened the reserve to development. For example, Montgomery allows the extension of water and sewer into the reserve for churches and other so-called private institutional facilities, such as day-care centers, a practice the council is considering ending.

Another county policy allows farmers who owned their property before the reserve was created in 1980 to build houses for their children without having to abide by normal zoning restrictions. It was meant to promote family farming, but county officials say they have anecdotal evidence that property owners have built houses using the "child lot" provision only to sell them to people not related to them.

How many times this has happened or even how many child lots exist is unclear, which some say is part of the problem.

"We can pass legislation, but the reality is we have clear legislation in the books," said council member Michael Knapp (D-Upcounty). "It's just a matter of getting people to enforce it."

Perhaps the most ambiguous county policy governing development in the reserve is the one that opened the door to sand mounds.

When writing the master plan that created the reserve, the Planning Board prohibited the use of "alternative" sewage disposal systems. In the early 1990s, Nancy Dacek, then the council member who represented the upcounty, was approached by a farmer whose parents had to move from his property because he could not get a traditional septic system to work. Dacek said that led her to ask the council to approve the use of sand mounds, which by then had become popular across the country.

Saving the Reserve

Dacek now says the policy the council approved was too vague. She and others believe that sand mounds should be used only when existing septic systems fail or when children of farmers legitimately want to live on the land.

Royce Hanson, chairman of the planning board that created the reserve, also cautioned against the use of sand mounds. "They permit pods of development to occur in such a way that it fragments the agricultural land and therefore runs against the purpose of the zone and particularly of the master plan," he said.

"It's an acceptable system," said Raquel Montenegro, associate director of the Maryland-National Capital Building Industry Association. "It has a successful record here in Montgomery County."

Jeremy Criss, the county's agricultural services chief, said taking away the right to build sand mounds could hurt farmers by reducing the equity on their land. "If the county wants to limit the application of sand mounds, I think it has to be done in a very careful way so that it is sensitive to the rights of the landowner," he said.

A dozen or so sand mounds could end up next to Schaudies's farm if Winchester Homes, a company that builds communities in Maryland and Virginia, has its way. Planning Board officials point out that the company will build 15 homes rather than the 28 it proposed in January 2003.

The Stoney Springs project, as it is known, has galvanized the community. Supporters of the reserve fear it will signal to other developers that they can use sand mounds to bypass the lack of public sewer lines. John Monacci, vice president of operations for Winchester Homes, declined to comment.

"It's more than a small battle over one piece of land," said Michael Rubin, a real estate investor who owns more than 3,000 acres that he has put into preservation. "To many of us here, this is a battle to save the agricultural reserve."

Larry Schaudies, a horse farmer near Poolesville, fears mound drainage systems will allow development to encroach on his land. "They're ruining the land for agriculture," he says of the systems, which he calls "a cheat in terms of the intent and the spirit of the ag reserve."

A development of 15 single-family houses near land owned by Larry Schaudies and his wife, Jo-Ann, would rely mainly on sand mounds for sewage disposal.