Mary Bourassa was wearing her recycling uniform yesterday: a bright red T-shirt declaring the Fourth of July a "Recycling Celebration" and a green plastic bag tied through a loop of her pants.

As captain of a group of volunteers who gave up the holiday to collect recyclable glass and cans from special receptacles on the grounds of the Washington Monument, she spelled out the duties to her crew.

"Okay, two of you check the boxes in the back row, and two do the ones closer in," she said. "Take a bag with you. Now, two more need to retape the signs on the boxes. Any questions?"

The 200 or so volunteers were recruited by Science Applications International Corp., an environmental protection support contractor that had collected recyclable trash from the Mall during April's Earth Day rally.

Science Applications and Browning-Ferris Industries, a waste management firm, had asked the National Park Service if they could assist in the cleanup during yesterday's celebration. Their offers were accepted.

National Park Service spokeswoman Sandra Alley said 124 tons of trash were carted from the monument grounds in 1988, the most recent year for which a figure was available. "The Fourth is one of our most intensive trash days because the activities last a long time," Alley said.

The spokeswoman said the volunteer effort will cost the federal government nothing. In fact, Alley said, any profits from the recycling will be given to the Park Service.

Peter Marroletti, a district manager for Browning-Ferris, said the day's effort probably would produce a profit.

"Aluminum cans bring $1,000 a ton," he said. "We are expecting a lot of cans today." The glass collected in the effort isn't expected to generate any profit, he said, since it sells for less.

Yesterday afternoon, Janelle Derwees and Reagen Romine found that the can boxes held far more than the bottle boxes. Following Bourassa's directions, they checked the containers along a walkway on the south side of the monument.

Derwees spotted two crumpled beer cans on the grass. "Are these empty?" she asked politely of two men tossing a frisbee nearby. "We'd like to recycle them."

"Yes they are, but we're already recycling," said Gary Pfadenhaver. "We've already dumped three cases of cans in one of those boxes."

Derwees carried the two cans to a box; inside were dozens of others. She added two more to the growing pile.

By late afternoon, only grass could be seen between the blankets spread out around the base of the monument. And all that green looked good to the National Park Service's regional superintendent, Arnold Goldstein, who is responsible for the cleanup.

"Usually by this time we'd have trash everywhere," he said. "This is very different. There is no trash."