Over time, surface soil at Firing Range 1 has become laden with lead ammunition fragments due to security personnel training. And disposing lead contaminated soil at a hazardous waste landfill is not cost effective. Therefore, in FY98, ANRC researchers began investigating alternate methods for separating lead from the firing range soil. The method found by ANRC researchers Dr. Desmond Lawler and Dr. Howard Liljestrand of The University of Texas to be most promising combines soil screening with a technique known as soil washing. First, soil is screened to remove large fragments of lead.
Screened soil is then mixed, or washed, to remove and separate the remaining lead from the soil.
Following mixing, solids and liquids are physically separated. The solid material is then subjected to additional rounds of washing until the desired amount of lead is removed. A final wash using tap water is performed to raise the pH of the solid material above treatment level. In laboratory experiments, a total of six washes were required to achieve 98 percent lead removal. On a large scale project, implementing such a batch mixing system would not be cost effective due to the number of washing batches required.