During the tests, 57 mm rounds were fired straight up. The book includes a picture of workers digging up the fallen shells.
The Department of Natural Resources bought Newtowne Neck in 2009 and opened the 776-acre state park. It includes seven miles of shoreline, a boat launch and walking trails.
Responding to the 911 call on New Year's Day, St. Mary's County sheriff's deputies closed the area and contacted the state fire marshal. The fire marshal's bomb squad confirmed that it was a military munition and called the Army Corps of Engineers. The 55th Explosive Ordnance Disposal unit from Fort Belvoir, Va., detonated the shell.
Carl Dubac, whose waterfront property is next to the park, was watching television when he felt the blast. The former Marine Corps test pilot figured an overenthusiastic flier at Naval Air Station Patuxent River nearby had accidentally broken the sound barrier, unleashing a sonic boom.
His wife said she knew it was an explosion.
"It was too loud," Franziska Dubac said. "It was like something exploded not right on top of us, but right next door."
Bouch said bomb-disposal protocol requires that such items be blown up.
"When you're talking about something that old, the potential for instability is paramount," he said. "You don't take them anywhere."
The Dubacs have lived alongside Newtowne Neck for 22 years. They walk and bike through the park. Neither had any idea that ordnance might turn up there.
The fire marshal's office, the state park service and the Corps of Engineers converged on the park, interviewing neighbors and sweeping the shoreline with metal detectors in a search for more munitions.
They have found 27 suspected pieces to date, including 57 mm rounds; 23 have been confirmed to be military ordnance.
When several were found underwater, a team from Naval Surface Warfare Center Indian Head was called to destroy them.
The Corps of Engineers is reviewing real estate records to determine whether Newtowne Neck is a Formerly Used Defense Site — in which case, spokeswoman Andrea Takash said, the agency would take over the effort to find and neutralize the munitions. For now, the Corps of Engineers, fire marshal and park service are working together.
As the research continues, questions appear to outnumber answers.
"We're still trying to ascertain why these were there," Bouch said. "These are World War II-era devices. Obviously, we have to go way back into archives."
If you find suspected ordnance
The Army Corps of Engineers advises people who encounter possible military ordnance to practice The Three R's:
•Recognize that any suspicious objects should not be touched under any circumstances.
•Retreat, or carefully leave the area.
•Report immediately what was found and its approximate location to the police.