The National Park Service has gained a scenic waterfront bike trail in Alexandria and more than $400,000 worth of bike trail improvements in settling its suit against the Potomac Electric Power Co. over waterfront land.

In addition, the Park Service is about to announce a master plan for developing Daingerfield Island, just south of National Airport, that will open the island's 107 acres of parkland to much broader public use.

The Park Service also has settled with the Marina Towers condominium, on Slaters Lane at the north end of Alexandria, winning a permanent easement for a bike trail along the Potomac River in front of the 13-story complex.

To date the federal government has settled with five of the 15 waterfront property owners, including the city itself, in its nine-year-old suit over who owns 39.5 acres of the historic Alexandria waterfront.

The city and the Park Service agreed last summer to a joint plan to rezone the 11.5 acres of city-owned land along the river. Most of that land is to be in a new parks zone that would allow some city development. The Northern Virginia Conservation Council has filed objections to that settlement, which U.S. District Court Judge John G. Penn is now considering.

Under the Pepco settlement, the power company has given the Park Service $250,000 and an easement along the shore that averages well in excess of 100 feet, according to Jack Benjamin, coordinator of the waterfront project for the Park Service. The easement gives a permanent public right-of-way along the river's edge.

In addition, Pepco has agreed to pay for construction of a steel bicycle and pedestrian bridge, cantilevered over the river from its plant. Construction on the bridge, to be about 150 feet long and estimated to cost $172,000, must begin by May under terms of the contract.

The Pepco settlement also involves a land swap, with the Park Service gaining half an acre near the water and Pepco a quarter-acre close to the power plant. Pepco gets clear title to its disputed waterfront land, including land under its "screen house," where water pumped in from the Potomac is screened of debris. The bike bridge will be attached to the screen house.

Most of the Pepco land is now fenced in and inaccessible to the public.

The $250,000 from Pepco will be used to build and landscape a new bike trail along the river's edge by the power plant, Marina Towers and through Daingerfield Island. This construction is expected to begin by early summer.

Construction of the bike trail through Daingerfield Island will coincide with the master plan, to be released next month after almost two years of discussion and public meetings. The plan is expected to call for preserving most of the island's woods and natural areas, and for building a larger restaurant overlooking the marina and Four Mile Run inlet. It also is expected to recommend adding a baseball field and grassy parking areas for weekend use.

Much of the island, once a large Park Service nursery, is closed to the public.

Under the Park Service's settlement with Marina Towers, a permanent public easement has been given the Park Service, ranging from a minimum of 12 feet directly in front of the building and its riverside swimming pool to widths of 141 and 171 feet at north and south ends of the Marina Towers property along the river. The trail will be fenced off and landscaped. The settlement drops all federal claims to Marina Towers property and thus gives the condominium complex clear title to its land.