HARRISBURG, Pa. -- A coal company will treat mine drainage on the land where Flight 93 crashed, according to an agreement reached with the state that could move the federal government closer to building a permanent memorial at the site.

PBS Coals Inc. and the state Department of Environmental Protection agreed in a consent order announced Monday that the company will also monitor water quality in the Somerset County area where the plane crashed on Sept. 11, 2001.

PBS Coals owns more than 800 acres at the site. The federal government can't take possession of the land until the mine drainage is addressed.

Because of the sensitive nature of the crash site, the company was prevented from treating the mine drainage there as it normally would. Instead, it had been pumping groundwater from an adjacent mine pool to lower the water table, thus stopping the discharge.

That water was being discharged into Lamberts Run, where it was treated to remove iron. The process was expensive and required PBS also to test for manganese, state officials said.

Under the new agreement, PBS will not have to be required to treat for manganese, unless the state finds elevated levels of the metal in the local water supply.

"We do not believe manganese will degrade Lamberts Run, as there is no evidence existing manganese concentrations will impact aquatic life, or create a problem for the downstream public drinking water supply," DEP Secretary Kathleen McGinty said. "The levels at the supply intake should be well below the level required for safe drinking water."

Flight 93 was en route from Newark, N.J., to San Francisco when it crashed as passengers apparently tried to rush the cockpit of the hijacked airliner. All 33 passengers, seven crew members and the hijackers died.

Construction of a $58 million permanent memorial and national park is scheduled to begin by 2009. A ribbon-cutting is planned for the 10-year anniversary of the attacks.

The park will encompass 2,200 acres, of which more than 1,350 acres include the crash site, debris field and land needed for visiting the national memorial. Another 907 acres would comprise the perimeter around the memorial.