Two memorials proposed for Constitution Gardens -- a major Vietnam War memorial and a small memorial to the signers of the Declaration of Independence -- have run into objections from federal planners.

Under bills soon to be given hearings in both the House and Senate, the Vietnam memorial would take two of the 46 acres of land in the four-year-old park. It would include sculpture, a place to inscribe the names of the more than 57,000 Americans killed in the war and possibly a carillon to provide musical tributes.

The National Park Service is concerned because the bills require the memorial to be constructed specifically in Constitution Gardens. The bills also give final approval of the design to only one federal agency, the Commission of Fine Arts.

The location and design of monuments and memorials built on federal land here traditionally are decided by the Park Service, Fine Arts and the National Capital Planning Commission. Additional advices comes from two other agencies, the Joint Committee on Landmarks and the National Capital Memorial Advisory Committee, formed in 1976 to help avoid uncoordinated spread of monuments here.

NCPA Chairman David Childs said this week he is concerned that in bypassing the normal planning process, Congress may be setting a precedent that will make planning chaotic. Such a precedent, he said, could allow groups that want a memorial to "shop around for a favorable agency," and then get Congress to give that agency final approval. "And there must be 1,000 memorials waiting in the wings Childs said.

Even Fine Arts Commission chairman J. Carter Brown said at a commission meeting this week he was concerned about legislation that called for a specific memorial site because this could set a precedent and open up the city to memorials in inappropriate places.

Although bills for Vietnam memorial have been introduced in Congress every year since the war ended in 1973, only last year a nonprofit group -- the Vietnam Veterans Memorial Fund -- was formed to raise money for a Washington memorial. Its cost is projected at $1 to $2 million.

The location of the memorial concerns the Park Service because it would have no say in the matter, and because the proposed location is Constitution Gardens, which the Park Service had hoped to keep largely free of memorials and monuments.

It favors the small memorial to the 56 signers of the Declaration of Independence, proposed for the island in the middle of the six-acre lake in Constitution Gardens.

But even that memorial, to be built with $350,000 in funds left over from the Bicentennial, has run into trouble with federal planning agencies.

Last week NCPC approved the idea of the memorial and its location on the island, but rejected the design that would put a semicircle of two-by-three foot steppingstones out into the lake.

Park Service planners liked the idea of a circle of stones -- half on the island, half in the lake -- for visitors to walk on. But the Commission of Fine Arts last month also opposed the steppingstones, and called for the memorial to be "simplified and limited to the island." The city's Joint Committee on Landmarks, which advises NCPC on national landmarks like the Mall, liked the steppingstones in the lake, but agreed the memorial should be "restudied and simplified."

The landscape architectural firm EDAW, which is doing the design, will return to the three federal agencies with modifications this spring.

Constitution Gardens, the major Bicentennial project in Washington, was constructed on the site of "temporary" World War I Navy Department buildings demolished in the late 1960s.