Fairfax County planners recommended yesterday that the Lorton regional landfill be doubled in size, despite intense community opposition and concern that the landfill is polluting local streams and rivers.

The proposed expansion would increase the size of the landfill from 300 acres to about 605 acres and place the dump within 500 feet of some houses.

The additional land would hold about 15 years of trash from Fairfax, the District of Columbia, Arlington County and Alexandria, according to the planners' report, which says the current landfill will run out of space in 1994.

The plan calls for converting the District's existing 52-acre Youth Center prison facility into landfill space and building a new Youth Center, for 800 inmates, north of Lorton Road, near the central prison facility. The cost of prison relocation is unknown, officials said, but it would be financed by fees levied at the dump.

"The fact that I'm going to pay to move the D.C. prison flips me out more than anything," said Angela Greenberg, who lives near the landfill. "What we're going to be building them will be a palace compared to what they have now . . . . If we had a bond issue, do you know anybody in Fairfax County that would vote to pay for them to move the prison?"

Greenberg said she also is concerned that the state Department of Waste Management has cited the county for allowing chemical residue to escape from the landfill into streams that empty into the Occoquan River and eventually the Chesapeake Bay. The chemical seepage, which Fairfax officials say is contained in runoff from the prison dairy farm, is occurring below the water supply intakes.

The landfill and the District's prison complex are on 3,000 acres in southeast Fairfax County that are owned by the federal government and used by the District under a long-term lease. Fairfax County has operated the landfill since 1982.

The Lorton reservation, as it is sometimes known, has been the focal point of tension between Fairfax and the District for years, with county residents complaining that their community is the dumping ground for city's most undesirable elements.

Lorton residents see the proposed expansion as flying in the face of their own community improvement efforts and have been fighting it for months.

They complain that expansion would increase odor, water pollution and truck traffic in their neighborhoods. They argue that the District has not taken steps to reduce the trash it dumps by repairing its incinerator, building a second incinerator and mounting an aggressive recycling program. Such steps are required in a memo of understanding between the county and the District.

"The county can no longer take a cavalier attitude with the District," said Steve Gageby, a civic activist who has lived in the Lorton area for about five years. "They have to rewrite the memos of understanding and give them real teeth and make the District comply . . . . The county has got to act now to cut off D.C. trash."

John W. di Zerga, director of the Fairfax County Department of Public Works, said the county had "written several letters and held several conversations" with District officials asking them to take more aggressive steps to reduce trash.

He said the county has little clout to enforce the memo of understanding because the District controls the land under its federal lease.

Tara Hamilton, a spokeswoman for the D.C. Department of Public Works, said the city is abiding by its memo of understanding with the county but, under a law passed by the D.C. Council, cannot construct a new incinerator until the city reaches a goal of recycling 25 percent of its solid waste, which she said is anticipated in 1993.

In the meantime, she said, the city is recycling at least 7 percent of its solid waste under recycling laws that went into effect in October.

She said a $5 million contract is about to be awarded to repair the city's existing incinerator, which will increase the amount of trash burned there from 200 tons a day to more than 600 tons in 1991.

According to Fairfax officials, the District sends about 2,500 tons of trash to the landfill every day. The county delivers about 2,600 tons to the landfill daily, but burns all but 200 tons, dramatically reducing its size and weight. Arlington and Alexandria together deposit roughly 300 tons a day of ash from their joint incinerator and another 40 tons of materials that cannot be burned.

The proposed expansion would come in two phases, according to the county staff report.

The first would expand the landfill to a 253-acre tract north of the current dump, which is also home to a prison dairy farm.

When that reaches its capacity in about a dozen years, the landfill would be expanded to the Youth Center site, which could accept trash for another three or four years, according to the report.

Under state law, the expansion needs only the approval of the county Planning Commission, which has scheduled a public hearing on the matter for Sept. 13.

Rep. Stan Parris (R-Va.) succeeded in July in getting the House to pass legislation requiring a formal environmental impact statement before any landfill expansion is permitted.

Fairfax officials argue that such an environmental study is unnecessary and could delay expansion for years.

Senate action on the bill is expected within a few weeks.

Fairfax Planning Commissioner John R. Byers, who represents the Lorton area, said yesterday that he will ask the commission to delay its public hearing for 90 days to see whether the Senate passes, and the president signs, the requirement for the environmental impact statement.