PITTSBURGH The Families of Flight 93 have reached an agreement with a coal mining company to purchase about 1-1/2 square miles of land needed for a planned national memorial, the organization said today.

The deal follows an agreement between PBS Coals Inc. and the state Department of Environmental Protection for the company to treat drainage from a former surface mine at the site about 65 miles southeast of Pittsburgh.

Financial terms were not disclosed, but the group said proceeds from the sale will be placed into a trust fund to pay for the operation and maintenance of the mine water treatment system. The transaction is expected to be completed within 60 days.

The National Park Service then plans to buy the 932 acres -- the largest single tract of land needed for the 2,200-acre memorial -- from the group of relatives of victims who died in the Sept. 11 terrorist attacks.

Flight 93 was en route from Newark, N.J., to San Francisco on Sept. 11, 2001, 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.

"This is very significant," said Patrick White, vice president of Families of Flight 93. "It represents all interested parties, citizens across the country included."

The transaction will not include key land needed for the memorial, including the crash site, he said.

An appraisal of the property that includes the crash site was completed last week and has been submitted to the National Park Service, White said. An offer is expected within weeks, he said.

The group continues to negotiate with other property owners over the acquisition of additional land needed for the memorial, White said. A total of about 300 acres still must be purchased, he said.

The agreement with PBS Coals includes roughly 27 acres that will be donated by the company.

Rep. Bill Shuster, R-Pa., said the land transfer agreement was "the culmination of months of careful negotiations" among the parties.

The federal government would have been unable to take possession of the land before the mine drainage had been addressed.

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

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

Flight 93 National Memorial Project: http://www.honorflight93.org

National Park Service Flight 93 National Memorial Project: http://www.flight93memorialproject.org