Local residents and officials are hotly contesting requests to create a special zoning category that would transform the Shady Grove area into a superdevelopment of commercial and residential complexes nicknamed "Rockburg" that would sweep west of I-270.

Montgomery County planners say they need the proposed Mixed-Use Planned Development zone currently before the Montgomery County Council to shape into orderly clusters the millions of square feet in office space and thousands of housing units they believe developers would bring to several tracts between I-270 and Rte. 28.

But officials in Rockville and Gaithersburg and residents of the surrounding area say that creating that zone--which planners are requesting first as a tool for developing the 211-acre Washintonian Country Club tract--would present a fait acompli, opening the floodgates that would commit Shady Grove to intense building as the zoning is applied to other tracts in that area.

They also say they fear that county planners assume too much, and that questions of road capacity and timing of development--and whether the market will support that development--remain with no solid answers.

MXPD would allow office and housing structures to be combined in condensed areas on the same tract; normally they are spread along separate parcels. Lawrence A. Ponsford, the county's principal urban planner working on the overall rezoning of the Gaithersburg area, said MXPD would cut down the sprawl of development, and keep much of the open space between small city-like clusters.

But opponents emphasize that MXPD would mark off land for intense construction. Gaithersburg Mayor Bruce A. Goldensohn told the council at a hearing on July 14 that launching the MXPD zone would put 19 million square feet of office space in the 2.7-square-mile Shady Grove area.

"That's more than what's in Rockville and Gaithersburg right now," Goldensohn said. "That's too much. . . . We're not looking for another Silver Spring."

Lyn Coleman, a planner for the county's northern planning department, said her staff is making final changes in the first comprehensive rezoning of Gaithersburg since 1971. The county council is expected to vote on that and the MXPD classification in September, according to Ralph Wilson, a council staff director.

Coleman said that planners have designated the Shady Grove area for development based on projections of Montgomery County's Economic Development Commission and indications of strong developer interest in Shady Grove.

However, leasing has fallen off recently along the I-270 corridor of office campuses, according to Patricia A. Terry, vice president for the suburban Maryland office of Julien J. Studley Inc., a national office-leasing company. More than 83 percent of the county's 1.2 million square feet of unleased office space lies between Democracy Boulevard and Germantown, she said.

Projects built in Shady Grove will have to compete for customers with similar, urban-style residential and commercial complexes scheduled for construction along Metro's Red Line at Chevy Chase, Bethesda, White Flint Twinbrook and Rockville, all due to become available in the next five to seven years.

Real estate specialists say there is more interest in close-in suburban locations, and that Fairfax seems to be attracting more distant firms as defense contracting under the Reagan administration has stepped up activity in Northern Virginia.

Currently, a partnership of Eig Enterprises and Ackerman & Co. of Atlanta is planning 3 million square feet of offices, 150,000 feet of retail shops, and up to 1,500 mid- to high-rise apartments for the 211-acre Washingtonian golf course tract that runs parallel to I-270, Ponsford said.

Farther south, planners have marked another 210 acres aroud the Shady Grove Adventist Hospital for development of a high-technology biomedical research park to be known as Shady Grove Life Sciences Center.

Another million square feet of offices and 480 apartments would go on a tract west of Shady Grove Road, just south of the Crown family farm on Fields Road. Although the Crowns want to continue farming, planners have tagged their land for future construction of more than 2,000 attached houses, the smallest of which would be town houses, Ponsford said.

Planners aim to concentrate half of the buildings on 20 percent of each site, he said. "What we're doing is creating the effect of a high-density project by clustering it together--piling it all in one place. . . . Each part supports and is supported by the others. Residential supports office, office supports retail and restaraunts, and they support hotel."

He said it would differ from the I-270 complexes because each development would have a multitude of uses that would share parking facilities and create a base for Ride-On bus service.

"Without creating a city out of it, you create the context where you can get some urbanity out of it, get enough [types of activities] going to make an amenity-filled environment," Ponsford said.

Planners have described a "pedestrian spine," an alignment of these complexes on their various tracts that would leave open areas surrounding them. Ponsford said that officials only hope to get 25 percent of the people who would live in these developments working there as well. The rest would join the commuters from Shady Grove neighborhoods who must fight daily tie-ups on the region's traffic-choked roads.

Coleman said that road expansions are on the way for Rte. 28 and the new I-370 "cross-county connector" to the Shady Grove Metro station.

But local residents and officials question whether those roads will be timed to match construction, and whether they will be sufficient.