Prince George's County officials announced plans yesterday to build what they say will be the nation's largest facility to recover recyclable materials.

The county will also expand its voluntary residential recycling program by 50 percent this fall.

County Executive Parris Glendening said the county's recycling program is expected to encompass all single-family houses in the county -- more than 160,000 -- by the end of 1992.

"The local, national and foreign environment is in trouble," Glendening said at a news conference yesterday morning announcing the initiatives. "Prince George's recognizes this and we are making significant advances in cleaning the environment."

Known as a material recovery facility, the plant will be located at the Hampton Park Industrial Park in the Capitol Heights area. It will serve as a place to sort, separate and process more than 70,000 tons a year of recyclable material, including newspapers, cardboard, glass, aluminum, plastic, tin and bimetal, a material commonly used to make soda cans, Glendening said.

The Rhode Island Central Landfill in Johnston, R.I., says it is the largest facility of this type in the country, processing just under 70,000 tons of material a year, according to Barbara Yuhas, chief of the Prince George's County Office of Recycling.

The Prince George's facility will be built by Sanford Cos. at a cost Yuhas said will be $3 million to $5 million. The county still is negotiating a contract for construction. The facility will be operated by New England CRInc., which also runs the Rhode Island facility, and leased by the county.

Construction is set to start this fall on the five-acre complex, which the county will have the option to purchase after the lease expires, according to Yuhas. The project is expected to be completed by midsummer or early fall of next year, she said.

The facility will cost $2 million a year to operate. But the county hopes to make $4 million a year selling the recyclable materials once the plant is in operation, Glendening said.

The expansion of the county's curbside collection program, already the largest voluntary multi-material program in Maryland, increases the number of single-family households eligible to participate from 22,000 to 35,000. Recycling officials estimate that more than 10 percent of the waste in the county will be recycled by 1991.

The eight areas participating in the expansion are Berwyn Heights, Forest Heights, Hyattsville, New Carrollton, North Brentwood, Seat Pleasant, Southlawn (Oxon Hill) and West Laurel. Collection in these areas is scheduled to begin this fall.

Currently, aluminum, glass, newspapers, corrugated paper and other materials are recycled as part of the county's program. Residents bundle newspapers and cardboard and place other materials in round receptacles that are picked up weekly in front of their houses.

In October, the county will start recycling plastic. Until the material recovery facility is completed, a plastics recycling plant in Baltimore will process the collected plastics.

"By recycling plastics, we can further extend the life of our landfills," said Glendening, adding that plastics account for more than 30 percent of the county's trash by volume.

Martin W. Walsh Jr., Maryland secretary of the environment, called the expansion ambitious yet pragmatic.

"We knew they were serious before this, but this shows Prince George's commitment to the environment," Walsh said.

In a separate statment, Walsh announced that 20 of 24 Maryland jurisdictions had submitted recycling plans to the Maryland Department of the Environment. The Maryland Recycling Act of 1988 required that jurisdictions submit a plan by July 1 and that the plans be approved by 1992.