The agreement gives the National Park Service access to the land, including the site where the plan crashed, and allows for the planning and construction of the memorial.
The three also agreed to let a court determine the value of the land. Patrick White, vice president of the Families of Flight 93, and Patrick Svonavec, the attorney for Mike Svonavec, the treasurer of the company, characterized the deal as an amicable condemnation.
Families of Flight 93 last month asked the Bush Administration to seize the land after negotiations with Svonavec to buy the parcel stalled.
"I am proud and pleased that we now have an agreement that delivers the property to the National Park Service so they can complete the project in a timely manner," Michael Svonavec, president and treasurer of Svonavec, Inc., said in a statement.
"The agreement allows the parties to cooperatively move forward on a methodology by which the evaluation will be determined."
Patrick White characterized the property as the "soul" of the memorial.
Under the agreement, Svonavec will donate six acres that encompasses the actual impact site. He has said he did not want any money for that parcel.
"I feel a sense of relief and accomplishment, a sense of gratitude for those who've participated to get us here. I'm certain that those feelings will evolve into action that will renew our effort in the days and weeks ahead," White said. "We're very optimistic. It's a real watershed day."
The planned memorial is to cover more than 2,200 acres, and the families had said ground had to be broken early this year in order for a memorial to be build for the 10th anniversary of the crash in 2011.
Flight 93 was en route from Newark, N.J., to San Francisco on Sept. 11, 2001, when it was diverted by hijackers. The official 9/11 Commission report said the hijackers crashed the plane as passengers tried to wrest control of the cockpit.
