Sifting through the past: Cleanup of buried “bomblets” continues at Scioto Ordnance Plant

Published June 30, 2014
Contractors use the Thermal Flash Unit, which processes the remaining metal to remove any particles of white phosphorous.

Contractors use the Thermal Flash Unit, which processes the remaining metal to remove any particles of white phosphorous.

Sifting through mounds of soil and safely detonating M74 bomblets, or WWII-era bombs, has been a daily task for environmental workers on site at the former Scioto Ordnance Plant in Marion, Ohio. Workers are unearthing small M74 bomblets that were discovered in a burial pit on the property.

Workers have safely detonated 2,883 M74s and have run approximately 2,000 cubic yards of soil through a high energy sifter to clear it of any munitions debris.

"This was a complex removal action," said Dr. David Brancato, U.S. Army Corps of Engineers (USACE) Louisville District technical manager for the project. "Safety of the community and the workers has been our top priority, and with over 13,000 person hours spent removing and decommissioning the M74s, we are proud to say that worker and community protection was achieved."

USACE oversees the cleanup of the nation’s Formerly Used Defense Sites (FUDS), and the Scioto Ordnance Plant has been an ongoing environmental restoration effort for the past 17 years. In the fall of 2013, small M74 bomblets were successfully cleaned up from a lagoon on the property, but led to the discovery of more buried M74s that needed to be unearthed when the weather warmed in the spring of 2014.

The three-acre area was surveyed in late April with geophysical mapping and one burial pit of M74s that were left buried on the site in the 1940s was confirmed. Pit excavation began May 16 to unearth the bomblets, which were four feet below ground level.

USACE’s contractor, CAPE Environmental Management went right to work destroying the munitions debris, which involves a three-step process. First, workers safely detonate the unearthed bomblets to inert the white phosphorous by simply exposing them to air.

"The detonation of the M74s vents the white phosphorus to the air, causing it to safely burn out," said Brancato. "Detonations were controlled to ensure neighboring citizens and businesses were informed and protected from the blasts."

Next, the remaining metal is processed in a Thermal Flash Unit (TFU) to remove any remaining particles of white phosphorous. Lastly, the surrounding soil that has been excavated is processed through a high-energy sifter to expose any particles of white phosphorous to the air, causing deactivation of the white phosphorous.

"Only a few TFUs are available this side of the Mississippi, and we were fortunate through the efforts of our contractors to procure the unit, which offset any safety concerns of the bomblets’ casings retaining any particle of white phosphorous," said Brancato.

Detonations were completed June 6 and site restoration was completed by the end of June 2014. After the Remedial Action Construction Report and the No Further Action Proposed Plan and Decision Document are completed—expected by June 30, 2015­—the project will be closed.