Corrosion of unexploded ordnance in soil-field results

Unexploded ordnance (UXO) are found on 400 000 Ha of land across 1400 different sites in the United States. In many cases, UXO contain high explosives posing a risk to groundwater quality. This paper provides results from a field survey of 14 inactive Army ranges distributed throughout the mainland United States. Metal samples and adjacent soil were collected from 161 UXO. Soil samples were analyzed for a variety of chemical and physical properties. Metal samples were analyzed for pitting corrosion. Climate data were also compiled. Of these analyses, only rainfall correlated with extent of corrosion. Samples had been buried from the Civil War era through the 1990s. Photographs taken in the field illustrate that corrosion occurs more rapidly on the underside of a UXO. Field observations also revealed that low-order detonations and UXO are difficult to distinguish in the field. The deepest individual pit measured on any of the 161 metal samples was 2400 microm. Low rainfall environments had shallower average pit depths (590+/-130 microm)than moderate and high rainfall environments, which produced deeper average pit depths (940+/-90 microm). The UXO studied in this effort were not a significant source of explosives to the unsaturated soil environment.