Ordnance Corrosion Study

[Lenny Siegel <lsiegel@cpeo.org>]

ARMY STUDIES UXO CORROSION

Increasingly, explosive compounds are being detected on military
munitions ranges. Rarely, however, are the precise sources known. Are
the substances there from disposal or training? Were they released
through corrosion, or by low-order detonation? It turns out that very
little study has been done on the fate and transport of explosive
compounds in munitions.

To fill this gap - in the furtherance of uninterrupted range use - the
Army Environmental Center's Range XXI Program is supporting research by
the Aberdeen Test Center (ATC) on the corrosion of bomb and shells. ATC
researcher Joseph Bucci presented his study at the UXO [unexploded
ordnance] Conference in Atlanta last week.

Bucci and his colleagues are drawing upon studies of other buried
metallic objects, such as culverts, and they are developing models based
upon several soil variables. At this stage, they are only looking at
conventional ordnance in "landlocked" soil. 

In landlocked soil - that is, where steel-shelled UXO is never immersed
in water - corrosion is an electrochemical process that depends largely
upon three, relatively easy to measure, variables: resistivity, pH, and
redox potential. Under typical conditions, corrosion creates a layer of
rust or calcium carbonate that protects the ordnance against additional
corrosion.

Bucci has concluded that there is a critical thickness, above which
corrosion is not likely - under normal soil conditions - to penetrate
the metal cases (skins) of UXO. Future studies, to be conducted at
Aberdeen Proving Ground and other UXO sites, are being designed to
determine that thickness, as a function of the three measured variables.
Results of those studies could lead to the segregation of weapons impact
areas by ordnance size, since smaller weapons tend to have thinner cases
and are thus more likely to corrode through and leach toxic substances.

Obviously, this kind of research could be broadened to determine the
fate and transport of munitions compounds in a much greater variety of
soils and water conditions. A comprehensive study of munitions fate and
transport would prove valuable, not just for test and training ranges,
but for determining ways to restore actual battlefields. As evidence of
the longevity of buried munitions, Bucci points to shells from the 1916
Battle of Verdun and even cannonballs possibly deposited in the
Baltimore harbor as Francis Scott Key wrote the Star Spangled Banner a
century earlier.

-- 


Lenny Siegel
Director, Center for Public Environmental Oversight
c/o PSC, 222B View St., Mountain View, CA 94041
Voice: 650/961-8918 or 650/969-1545
Fax: 650/968-1126
lsiegel@cpeo.org
(PLEASE NOTE THAT WE ARE PHASING OUT
MY OLD E-MAIL ADDRESS: lsiegel@igc.org)
http://www.cpeo.org