The National Park Service dealt with discoveries of old explosives at two sites in recent days: detonation cord near Glen Canyon Dam in Arizona and cannon ammunition embedded in a monument at Antietam National Battlefield in Maryland.
Workers found several boreholes containing detonation cord along a restricted service road near Glen Canyon Dam, outside Page, Arizona. The material, a flexible line used to set off blasting charges, was traced by an explosive ordnance disposal team to the dam’s construction in the 1950s and 1960s.
Officials said the discovery posed no threat to public safety and presented a low risk to the dam. However, Chains Road and The Chains day-use area were temporarily closed while officials considered how to address the material. The wider recreation area remains open, but the closure affects a shoreline spot used for swimming, fishing and picnicking. No reopening date was announced.
The discovery came after construction crews blasted diversion tunnels through sandstone and excavated foundations for the dam, which began construction in 1956. The newly found cord has not been linked to the ceremonial first blast, remotely triggered by President Dwight D. Eisenhower that year.
At Antietam National Battlefield, Marine Corps explosive ordnance disposal specialists removed ten pieces of cannon ammunition from the concrete base of the O.T. Reilly Monument. Park officials announced the removal plans on October 21. Because the ammunition might still contain explosives, the operation required temporary closures around the visitor center, Dunker Church, nearby roads and two walking trails.
Oliver T. Reilly, a local battlefield witness who later worked as a guide and historian, dedicated the monument in 1927. He set ten artillery projectiles from his collection into its base. The ammunition was scheduled to be taken to Quantico, Virginia, and the monument returned to a rebuilt base.
The National Park Service has procedures for dealing with unexploded munitions and construction explosives. The agency began reviewing museum collections for potentially explosive ammunition in 2022 and issued guidance on handling historic munitions that year, followed by further safety procedures in 2023.
Sources: Outside.