The Montgomery County Planning Board, after months of debate on one of the county's most protracted zoning cases, has endorsed a Rockville company's plan to develop a quarry on 530 acres of farmland outside Boyds, a rural town 18 miles northwest of Washington.

The board's action, a 3-to-2 vote recommending approval of a zoning map amendment, was a major victory for Rockville Crushed Stone Inc., which has been battling area residents over the quarry for the past seven years.

"It's obviously much better to have the planning board recommending for us instead of against us. We think it will help our chances," said James G. Topper, a company vice president.

The corporation, which operates a quarry in Travilah, is seeking to rezone the land from agricultural uses to a new "mineral resource recovery zone" that would permit the mining of millions of tons of diabase rock.

The request is pending before a county hearing examiner who is expected to make a recommendation to the county council sometime this summer. A decision by the examiner, and ultimately the council, which has final say on all zoning matters, is unlikely to settle the issue, however.

The Boyds Civic Association and adjacent property owners already have filed two suits in Montgomery County Circuit Court, challenging the rezoning process.

Lawyer William Chen, who represents the residents, said his clients did not attempt to contest the board's action last week, because the board already has violated their "due process rights" by holding "improper public hearings."

The allegation is one of two major issues raised in court papers. The suits also charge that the council adopted "illegal" zoning standards when it approved an amendment to the Boyds master plan last February.

The amendment sets forth a number of conditions that Rockville Crushed Stone must comply with to operate the quarry under the mineral resource zone.

"Those conditions are illegal because they're not enforceable," Chen said. "If you are going to rezone land, you look to the zoning ordinance. Those master plan standards are not contained in the zoning ordinance."

The property, which is wooded in some parts, open in others and criss-crossed by two streams, is bounded by B&O railroad tracks to the north and by White Grounds Road and Bucklodge Lane on the west and east.

Most of the land was zoned for rural uses in 1958. The quarry was first proposed in 1978, when the county updated the Boyds master plan.

From the outset, the proposal was hotly contested by area residents who raised concerns about dust, noise, truck traffic and storm water run-off, which threatened to contaminate area ground water.

The county ultimately did not include the quarry in the plan because local zoning ordinances did not adequately regulate quarry operations, Chen said.

To address the problem, the county adopted the mineral resource recovery zone in 1980. Rockville Crushed Stone filed its rezoning request the following year, according to planning records.

The planning board and the council have spent the time since then drafting an amendment to the master plan to "delineate the scope" of review for a quarry operation.

The amendment was approved last December, clearing the way for a final round of negotiations with the company that led to the planning board's vote last week.

To avoid generating heavy truck traffic in the Boyds area, the company has agreed to ship its stone by rail to two locations near Gaithersburg. From there, the stone will be loaded on trucks.

The company also has agreed to screen the property, monitor ground water, and to comply with county noise and air pollution standards.

Planning Board Chairman Norman Christeller, who supported the zoning change with board members Max Keeney and Mable Granke, said the company's development plan included "a comprehensive set of safeguards" to protect the Boyds community.

The state transportation department, Granke noted, considers the Boyds quarry an important supply for diabase rock, which is used extensively in road construction.

The quarrying operation would be carried out in three phases over the next 30 years. The company agreed to reclaim the land and make it suitable for recreation and the construction of homes when the supply is exhausted.