A series of leaks in underground propane gas pipes forced the evacuation of 75 people yesterday from a federally subsidized housing project for low- and moderate-income families in the Good Hope area of Montgomery County.

Officials of the Montgomery County fire marshal's office said yesterday they had been monitoring the leaks at Great Hope Homes north of Colesville as early as Dec. 8, when directors of the nonprofit housing development reported the leaks.

Officials said the leaks occurred in dozens of joints in the underground piping system that feeds furnaces and stoves in the development and that 75 of the project's 1,500 residents were evacuated when unacceptably dangerous levels of gas were recorded beneath 12 town houses on the tract.

Smaller amounts of gas have been found in the ground beneath a "number" of the development's 104 other town houses, according to Lt. Leonard King of the fire marshal's office.

"We've put out directives saying there is to be no smoking and no open fires in the area," King said.

Most of the evacuated residents were temporarily sheltered last night at the nearby Good Hope Community Center, where Red Cross workers provided sleeping cots, food and blankets.

O.D. Field, president of the project's board of directors, said the development was built four years ago with a $2 million grant from the U.S. Department of Housing and Urban Development. He said the subdivision was intended to replace a collection of ramshackle shacks, buses and trailers that previously stood on the tract.

The project was developed by Leonard Kapiloff, owner of the Montgomery County Sentinel newspaper, who said last night he was "stunned" at learning of the propane leaks. He said theyfinished developing the project four years ago and no longer have a financial interest in it. The project was designed and built by Kollins and Kronstadt, a Montgomery County architectural firm.

Robert Wasser, a member of the project's board, said propane was chosen as an energy source for the development because it was the only source available. "Washington natural gas doesn't come out here and we couldn't find a supplier of oil," he said.

In early December residents complained of smelling gas and the project's board of directors asked the county Office of Economic Development for rehabilitation funds, according to Jacqueline Rogers, director of the office.

"My office contacted the fire marshal and together we decided to figure out a way to accurately measure the gas at the project," Rogers said. She said measurements were taken daily at "dozens" of locations around the five-acre tract. "It wasn't until today that the problem became acute," she said.

In the meantime, several plumbers were hired by the board to locate exactly where the leaks were in the galvanized steel piping, which lies three feet below the ground. "They found leaks at pretty much every joint or turn in the piping," Lt, King siad. "It got to a state of danger when we found pockets of gas directly beneath some of the town houses."

Rogers said the project's board of directors, in consultation with the plumbers, would determine today whether to attempt to patch each of the leaks or replace the entire propane delivery system. It would cost about $200,000 to replace the system and work could not begin until spring when the ground thaws, according to Rogers.

In the aftermath of a seven-alarm fire Wednesday in Anne Arundel County that fire officials attributed to leaking propane gas, Montgomery County fire marshals moved quickly yesterday to relocate those residents who were considered to be in the most danger.

Many residents first heard about the relocation when they returned home from work yesterday and found official notices on their front doors and their door locks changed, to prevent looting.

"I've got seven kids to feed and clothe and all of a sudden they tell us to move out," said Annie Williams, as she packed clothes, food, blankets and other odds and ends into an over-crowded station wagon.

We've known about that gas a long time. It should have all been solved sooner than this."