The US Army has been fined $59,220 (£40k) for alleged violations of its hazardous waste permit in Fort Wainwright, Alaska.
The facility is covered under a permit which requires the Army to notify the Environmental Protection Agency (EPA) of any new solid waste.
EPA said the Army violated its permit by failing to notify it when an explosives dump and weapons pit was left in June 2013.
It also failed to provide a required assessment of the dump, it added. The agency learned of the dump more than a year later in a technical memo from the Army’s contractor.
Lead, brass and other heavy metals from the munitions dump were eroding into the Tanana River at the time of the initial investigation in 2013.
In 2015, the Army conducted a partial cleanup at the site, removing more than 300,000 pounds of “Material Deemed As Safe,” 150 items identified as “Munitions and Explosives of Concern,” and 5,000 buried and unfired 50 caliber rounds.
The Army will conduct an additional cleanup in 2016.
Ed Kowalski, Director of EPA’s Pacific Northwest Office of Compliance and Enforcement, said: “Compliance with hazardous waste permits helps us protect Army staff and the community from potentially dangerous materials.
“Failure to notify EPA could have delayed and impeded our ability to ensure timely, appropriate actions were taken to protect people and the environment.”