Federally owned sites near Union Station and at the long-stalled Southeast Federal Center on the Anacostia River waterfront will be considered as locations for a new Department of Transportation headquarters, according to government documents released last week.

The department wants to rent 1.35 million square feet of space near a Metro stop in the District, a lease that will be worth as much as $55 million a year to the landlord. The General Services Administration, the government's real estate agency, laid out detailed requirements for that consolidated headquarters last week in a draft version of what is known as a Solicitation for Offers, or SFO. That's the document that sets the rules for a government real estate search.

The department's 7,000 headquarters employees are housed mostly in two rented buildings, the Nassif Building at 400 Seventh St. SW and the Transpoint Building at 2100 Second St. SW. The agency moved into Nassif in 1970; its lease expires March 31, 2000. The lease on the smaller Transpoint Building expires in 2003. The GSA aims to make a decision about the consolidation before the Nassif lease expires.

The owners of the Nassif Building plan to try to keep their big tenant by proposing a major renovation.

Usually when landlords compete to snag a government tenant, they propose building on land they control. In this case, though, the federal sites are an added twist.

The Southeast Federal Center is a long-proposed collection of federal office buildings that is supposed to be built on a riverfront tract next to the Washington Navy Yard. Although the GSA has been talking about the project for years and has spent millions preparing the land, no agency has agreed to move there. For the Transportation Department's competition, the government is offering to sell would-be landlords ground at "fair market value" as determined by an appraiser.

The other government tract specified in the department's solicitation is a 100,000-square-foot plot behind the Government Printing Office at 730 N. Capitol St. NW. By itself, that's not big enough for the new headquarters, but the solicitation says the "GPO may be willing to convey an interest in this land" and suggests that "adjacent landowners" should get in touch with the printing office.

The Transportation Department's search is also different from the standard GSA space competition because bidders will not be required to complete detailed designs before a winner is picked. The usual requirement can make it very expensive for a developer to bid for a big federal tenant.

"I want to get lots of good feedback from market on this draft, because we're trying a different approach," GSA's Tony Costa said.

The GSA is accepting comments on the draft solicitation until Sept. 3; the full text is available on the Internet at www.evolv .com/DOT.

Net 2000 Signs Dulles Park Lease

Telecommunications company Net 2000 has signed a lease on 126,276 square feet of space at Dulles Park Technology Center in Herndon, a building under construction at 2180 Fox Mill Rd.

The 181,000-square-foot building, owned by Koll Metropolitan Partnership, is scheduled for completion next month.

Earlier, Koll had leased 36,685 square feet to the General Services Administration, acting on behalf of the National Park Service. The two leases account for 90 percent of the building's space.

Moe Hamilton and Joe O'Brien of Insignia/ESG represented Koll in both deals. The Irving Group represented Net 2000.

SAIC Signs Lease in Falls Church

Science Applications International Corp. (SAIC) has leased 89,302 square feet at 6565 Arlington Blvd. in Falls Church, which is 64 percent of the newly renovated building.

The computer systems company is filling all the remaining space in the building.

Moe Hamilton and Joe O'Brien of Insignia/ESG represented the landlord, Horne & Folger Associates. Kenneth Rudy, Jeff Groh and Nancy Liffman of Jones Lang LaSalle represented SAIC.

Sold

Velsor Properties LLC of Tysons Corner purchased four buildings in the Sullyfield Business Park in Chantilly for $15 million. The buildings, which total 215,000 square feet of office, industrial and flex space, are at 14120, 14121, 14140 and 14141 Parke-Long Court. The seller was Transcontinental Realty, which bought the four buildings in 1994 for $8.8 million. The broker on the transaction was Don Devine of Devine Commercial. . . . CMD Realty Investors sold One Monument Place, an eight-story, 226,000-square-foot building at 12150 Monument Dr. in Fairfax Center, to TIAA Realty. Costar Inc. reported the sale price as $34.5 million. Brokers Margaret Hirl, Lee Alexander and Bill Prutting Jr. of CB Richard Ellis handled the deal. . . . Castleton M St. LP bought the 40,500-square-foot office building at 2555 M St. NW from the Lauriston Co. for $7.15 million. Brokers Nicholas Pappas, Vernon Knarr, John Kyle and Nicholas Demas of Julien J. Studley Inc. represented the buyer. Brokers William Kaye and Drew Genova of Trammell Crow represented the seller.