D.C. police went public yesterday in their long-running battle with the U.S. Army Corps of Engineers to get a stretch of old railroad trestle pilings removed from the Potomac River off the Blue Plains sewage treatment plant.

Lt. Thomas McGlynn, D.C. police harbor master said the pilings constitute a serious hazard to navigation because they lurk just below the surface of the water at high tide. One man has been drowned in one of at least a dozen of accidents in which boats slashed their hulls on the pilings.

The pilings, which dated the days of the Civil War, just out of the water at low tide. But at high tide their tops are about a foot below the surface - enough to hide them from view but not enough to let most boats clear them.

The most recent wreck on the hazard occured 3:30 p.m. on Sunday, May 8. "Teh sun was shining, it was clear as a bell," said Charles W. Groover, who was piloting his new $10,000 Cobalt downriver from the Columbia Island Marina toward Pohick Bay Regional Park near Woodbridge.

Groover was heading home. His 17-year-old son had taken the boat up to the marina while Groover, himself, studied ment charts of the area. Groover said he recently purchased Commerce Department charts of the area. Groover said he did not look at the charts on the downriver trip, but said he stayed well inside the buous marking the channel.

"We were roughly abeam of Boiling Air Force Base doing about 30 or 35 miles an hour," he said, "when all of a sudden the boat wasn't moving even though the engine was still running. My son looked over the side and said, 'The outdriver propeller and coupling is gone.' And so it was."

Groover says he studied the charts afterwards and "damned if I know waht I hit."

On March 28, 1976, a 40-foot Chris-Craft struck the pilings and a salvage company estimated the damage at $8,000, police said.

The worst accident occured on Oct. 29, 1967, when an 18-foot runabout owned and operated by James C. Bryan Jr. hit the pilings. When Bryan tried to get the boat into Alexandria, it took on water and sank. Bryan drowned.

According to McGlynn who took reporters and photographers on a tour of the area off Marbury Point yesterday, D.C. police have been trying to get the Corps of ENgineers to remove the pilings for years. He said formal negotiations for the removal began last July, but the corps, which has jurisdiction in all navigable waterways, has refused to do the work.