AMEC IS removing spent ammunition from 7,500t of soil as part of the clean-up of a firing range at Fort Dix in New Jersey.
The $1.36M (£875,000) scheme is being carried out under RangeSafe, a US Army programme to support more effective, economical and environmentally friendly technologies to clean up and maintain the nation's firing ranges.
More 7,500t of soil from Range 25 is being cleaned using a soil washing process developed by subcontractor Brice Environmental Services.
Soil mixed with water runs through a series of screens and classifiers adapted from the mining industry to isolate the soil fractions that contain lead particles. These fractions undergo density separation in a 'jig' using upward-vertical water flow. The lead, being heavier than the soil particles, sinks faster and is retained while the water and suspended soil particles flow out.
'Our process can remove even very small lead particles, and it produces no secondary wastes for disposal, ' said Michael Warminsky, technical director at Amec's Somerset, NJ office.
'Also, because it is waterbased, it is dust-free and requires no air permits. When coupled with stabilisation, it provides best value to the client as both source removal and long-term soil stability are achieved.' After washing the soil is mixed with chemicals to bond any remaining lead to the soil particles and prevent it leaching into groundwater.
Sediment traps will be installed on the range to prevent runoff carrying lead off site. Berm soil will be conditioned so that future maintenance can be accomplished through dry sifting.