At least six cannonballs have been unearthed since construction began last year, mostly on the South Island. One was only found in September, said Larissa Ambrose, VDOT’s environment manager.

A find like this is considered live ammunition, until decided otherwise, and triggers a call for military explosives experts. In this case, personnel from the Navy’s Explosives Division and experts from Langley Air Force Base are called in to investigate – and construction usually comes to a halt.

“Until now (the cannonballs) were about 8 inches to 9 ½ inches, so they’re decent sized cannonballs,” Ambrose said. “It’s the construction people on the ground who find them. Their construction equipment gets stuck on those cannonballs.

Holma, whose specialty is the review of road projects, is usually consulted to assess whether something found qualifies for the National Historic Register.

Alas, cannonballs, some made of solid iron, others with gunpowder inside and probably used during the Civil War era, did not do the trick. Because the cannonballs were found inside an island made of “borrowed earth” from other places, they are only an isolated find, he said.

Among the criteria that the DHR seeks to examine, it is necessary to know whether the artefact is related to a historical event, to someone of historical importance, to something of architectural or archaeological significance, or whether it conveys historical information. After that, seven other characteristics are taken into account, including the integrity of the location. The cannonballs were not found in their original location, which disqualifies them as having historical significance.