LAWRENCE — Using saws, hammers and nails, teenagers and adults built garden beds at the former site of the Covanta trash incinerator.

The boxes are part of the finishing touches to what is now called Covanta Park on Manchester Street.

"We built a safe place for gardening because neighbors told us that's what they wanted," said Heather McCann, director of Groundwork Lawrence.

Helping build the boxes were: Plus Co., a program for special needs people in Lawrence; Green Team of Groundwork Lawrence; employees of New Balance; The Home Depot in Reading and Methuen; and members of Lawrence Community Development.

The five acres once filled with bricks, rubble, garbage and part of a smokestack, is now covered with grass and trees, swings, a playground, monkey bars, walking trails, and a pavilion in a rainbow of colors that overlooks Stevens Pond.

Forty volunteers built 26 of the 30 garden beds and had to stop because they ran out of wood. Green Team planted flowers, tomatoes, peppers, melons and squash in four of the gardens.

Volunteers will return today to finish the remaining beds and fill the ones made last week with soil.

Tennis Lilly of the Conservation Commission was elated to see the new park.

Lilly, who lived on Myrtle Street for 18 years, was instrumental in closing the incinerator.

"Every night I looked out my window and saw the smoke," he said. "To come back now and see an incredible park is deeply satisfying." A mural and full site lighting will be the next phase of the construction.

"It taught me the importance of service," Jennifer Pagan, 17, said. "The park not only makes people more welcomed, but it helps out the community and makes the city a better place."

This is the third time Leya Neilson, quality engineer at New Balance, volunteered to work in Lawrence. "It's great to give back to the community," she said.

The park has not only beautified the neighborhood, but it has brought wildlife back to the area. McCann has seen blue herons and a turtle in the water.

Eighty trees line the park, including crab apples, cherry, red maple, oak, birch and elms, which will soon attract birds for nesting.

The plant closed after 20 years in 1998 due to cost and pressure from the government to clean up.

TRC in Lowell did the cleanup. Matt Robbins, of TRC, said they found dioxins, arsenic, polycyclic aromatic hydrocarbons on the site, which they covered with 3 feet of clean soil to isolate the contamination from park users.

Money for the cleanup came from a $500,000 grant from the urban self-help program of the state Executive Office of Energy and Environmental Affairs.

Dioxins are a byproduct in the incineration of chlorine-containing substances, paper bleaching, and from natural sources such as volcanoes and forest fires; arsenic can be found in wood preservation, glass production, nonferrous metal alloys, and electronic semiconductor manufacturing and occur in oil, coal, and tar deposits, and are produced as byproducts of fuel burning (whether fossil fuels or biomass).

Frank Calandra, project manager, who wrote the cleanup design submitted to the Department of Environmental Protection said capping the contaminated soil was more cost-effective because it would have cost $1 million to haul it away.

"It was also safer because we did not have to take it somewhere else to dump it," Calandra said.

The land was owned by Covanta — hence the name of the project — which operates the Haverhill incinerator. The city purchased the land from Covanta.