A new plan for long-range development in Gaithersburg proposes to further intensify business, industrial and residential growth in much of the I-270 corridor, the fastest-growing section of Montgomery County during the last decade.

The plan, which will be discussed at an open house Saturday and at several public meetings during the next month, proposes two major changes to the present Gaithersburg-area master plan: making the 212-acre Washingtonian Country Club in Shady Grove a huge business, commercial and hotel complex instead of a residential development, and increased industrial, commercial and residential development around the Montgomery County Airpark.

The plan calls for expansion of the county-owned airport, already one of the busiest general aviation airports in the Washington region, by extending the runway and adding an instrument landing system to attract even more business and pleasure aircraft.

To accommodate this growth and relieve present congestion, extensive highway and street improvements are proposed in the plan, including widening many existing roads, putting additional interchanges on I-270 and building several new highways: the Intercounty Connector, I-370, and an Eastern Arterial and Western Arterial (Great Seneca Highway) that would parallel I-270 and relieve some of its traffic. The road improvements may be crucial because a shortage of state highway funds for area roads is forcing Montgomery County to limit growth around Gaithersburg and has just killed a Mobil Corp. plan to develop the Washingtonian Country Club.

The Gaithersburg plan proposes less growth in the Smokey Glen neighborhood adjacent to Seneca State Park, where residential land would be zoned for minimum two-acre lots. The Oakmont area on the southeastern edge of Gaithersburg city also would maintain its present two-acre zoning.

Proposals for two major areas targeted for development -- around the airpark and in Shady Grove -- now call for increased housing, "especially affordable housing" that employes of the many proposed business firms could afford to buy, says Planning Coordinator John Matthias.

Shady Grove and the airpark area also would become receiving areas for the new development rights that farmers in rural areas can sell to developers under the county's agricultural preservation program. Farmers who lost the right to develop their land under new rural zoning can now sell their development rights to developers in designated receiving areas. The transferrable development rights (TDRs) alone would allow close to 4,000 additional housing units in the Gaithersburg area, according to Matthias.

An open house will be held Saturday from 10 a.m. to 4 p.m. at Lakeforest Mall for residents who wish to discuss the master plan draft, which was prepared by the Maryland-National Capital Park and Planning Commission staff. Staff members will be at the open house.

A public forum to record citizen comments will be held Dec. 1 at 8 p.m. at Ridgeview Junior High School, 12100 Cheyenne Ter., off Quince Orchard Boulevard. The Montgomery Planning Board has scheduled two work sessions on the plan, at Ridgeview Junior High Dec. 7 at 8 p.m. and at its offices, 8787 Georgia Ave., Silver Spring, on Dec. 17, also at 8 p.m.