THERE'S POTENTIALLY grand news from one of America's most meticulously ruined landmarks. Union Station, where untold federal dollars and armies of bureaucrats converged for a Bicentennial savaging of a once-grand train terminal, may live again the way it always should have. New dollars and old ideas seem to be in place for a revival written off by all but the most chronic dreamers and train buffs.

It's still much too early for a visit, unless you're setting forth anyway to meet or take a train at Union Station, which in its current design requires a native guide and heavy-duty hiking shoes to get you from the front door to the tracks. But there are workers hacking their way through the forbidden territories inside where swamps, urban wildlife and other creepy products of neglect long ago forced the closing of what was once an awesome setting.

Transportation Secretary Elizabeth Hanford Dole, in her first month in office three years ago, went up to Union Station and announced an agreement -- with public and private money to make it real -- designed to bring back a semblance of the old terminal. In prospect is a mix of the original magnificence and contemporary commerce -- shops, restaurants, movie theaters and other attractions. Plans call for private developers to pay the government at least $1 million a year in rent. This, officials say, should cover outstanding debts and other costs.

Gone will be the huge pit that some hallucinating architects of the 1970s created for the central hall when they turned it into a "National Visitor Center" and hid all of the train tracks in almost another neighborhood. The pit will be hidden beneath concrete and -- here's the best part -- the train tracks will be put back where they belong.

Before the reopening expected next year or early in 1988, the developers could yet miss the mark. Just maybe, however, Union Station will live again as it should.