Corps begins Phase II Remedial Investigation at Plum Tree Island

Posted December 9, 2009
By Jerry Rogers
Norfolk District Public Affairs

12/09/2009 - POQUOSON, Va — The U.S. Army Corps of Engineers, or USACE, began its Phase II Remedial Investigation (RI) work at the southern portion of Plum Tree Island National Wildlife Refuge, a formerly used defense site.

The Corps re-mobilized a small crew in October to perform limited non-intrusive collection of geophysical data through December. There are no plans to perform detonations. Full mobilization of the unexploded ordnance team begins in January and runs through March 2010, with RI of anomalies and collection of soil, sediment and water samples for testing.

The primary focus of Phase II is to characterize the nature and extent of Munitions and Explosives of Concern (MEC) and Munitions Constituents, or MC, at the refuge, said Project Manager George Follett.

From January through March 2009, USACE and contractor Shaw Environmental, Inc., completed Phase I of the RI, which culminated in two munitions detonations.

"Work consisted of a 123-acre shoreline surface sweep from the top of the sand dune to the low tide line," said Alex Smith of Shaw Environmental. "The team identified and removed surficial material potentially posing an explosive hazard."

Approximately 263 Jet-Assisted Takeoff (JATO) rockets were recovered, along with bomb and rocket fragments. The only items found during the surface sweep that contained energetic material were six JATO rockets. These were disposed of by detonation, Smith said.

Additionally, eight tons of munitions debris, primarily consisting of empty JATO rocket bodies, was demilitarized on site, certified as hazard-free and transported to nearby Messick Point for temporary storage prior to disposal.

Phase I work included the geophysical investigation of a pre-planned percentage of 2,000 acres of the northern interior of Plum Tree Island, using sub-surface metal detecting. All accessible subsurface anomalies potentially representing munitions were excavated as part of the investigation.

MEC located in the sample areas included 13 World War I-era MK 1, 50-pound demolition bombs/fuses. The explosive ordnance disposal detachment at Langley AFB in Virginia worked with Shaw Environmental during munitions detonations.

"Our Phase I work went extremely well in large part to the outstanding support received from our key partners, the U.S. Fish and Wildlife Service, Virginia Department of Environmental Quality, Langley AFB, the city of Poquoson and the U.S. Coast Guard," said Follett.

Plum Tree Island National Wildlife Refuge was formerly known as the Plum Tree Island Range and was used for aerial bombing and gunnery practice from 1917 through the late 1950s.

The former bombing range, which consisted of approximately 3,200 acres, was transferred to the U.S. Fish and Wildlife Service in 1972.

With the exception of waterfowl hunting on Cow Island, which was not part of the bombing range, the refuge remains closed to the public due to the potential for encountering unexploded ordnance.

For more information on future fieldwork at Plum Tree Island, visit the Norfolk District Plum Tree Island web site.