1
Research Plan for ECM Required Earth Cover
Joshua E. Payne
1
, John Q. Ehrgott, Jr., Denis D. Rickman, T. Neil Williams; U.S. Army Engineer Research and
Development Center; Vicksburg, Mississippi, USA
Michelle M. Crull; U.S. Army Engineering and Support Center; Huntsville, Alabama, USA
Daniel L. Linehan; U.S. Army Technical Center for Explosives Safety; McAlester, Oklahoma, USA
Keywords: Earth-Covered Magazine, Above-Ground Magazine, ECM, AGM, Magazine, Earth Cover,
Safety Standards, Ammunition
Abstract
The U.S. Army has a large number of earth-covered magazines (ECMs) for storing ammunition and explosives. These
ECMs are generally sited for a maximum of 250,000- or 500,000-lb net explosive weight and designed to have a
minimum of 2 ft of earth cover as specified in DoD 6055.09-M. Over time, the earth cover may erode or settle resulting
in an earth cover that is less than 2 ft thick. In accordance with DoD 6055.09-M, the ECM must then be sited as an
above-ground magazine (AGM) impacting quantity-distance requirements and resulting in lower explosive quantities
that can be stored in the ECM. It is not clear that this requirement is realistic. To address this issue, the U.S. Army
Technical Center for Explosives Safety requested support from the U.S. Army Engineering and Support Center,
Huntsville and the U.S. Army Engineer Research and Development Center to address the issue of the effect of varying
earth covers for ECMs. Of interest is the point at which an ECM behaves as an AGM, from the perspective of a donor
of and an acceptor for explosive loading. This paper presents the initial series of experiments that will be conducted
at ¼ scale to begin to evaluate the effect on ECM loading due to varying earth cover thickness.
Introduction
The U.S. Department of Defense (DoD) has a very large number of earth-covered magazines (ECMs) for storing
ammunition and explosives. The majority of these earth-covered magazines are arch-type structures with widths of
26.5 ft and lengths varying from 40 ft to 80 ft. These magazines are generally sited for a maximum of 250,000- or
500,000-lb net explosive weight (NEW) and are designed to have a minimum of 2 ft of earth cover as specified in
DoD 6055.09-M, DoD Ammunition and Explosives Safety Standards [1]. Over time, the ECM earth cover may erode
or settle, resulting in an earth cover that is somewhat less than 2 ft thick. In accordance with DoD 6055.09-M,
paragraph V2.E5.5.3.2, the Earth-Covered Magazine must then be sited as an Above-Ground Magazine (AGM). This
potentially impacts quantity-distance requirements, usually resulting in the need to lower the NEW stored in the
magazine. The largest impact this has on siting is on the required inter-magazine distance (IMD). For example, with
less than 2 ft of earth cover, the side-to-side exposure IMD would increase from K1.25 (D = 1.25*NEW
1/3
) to K6 (D
= 6*NEW
1/3
). For 500,000-lb NEW, this would increase the IMD from 99 ft to 476 ft. Since the distance between
existing magazines cannot be changed, the storage capacity in this case must be drastically reduced.
The origin of the 2 ft of earth cover requirement is not documented. The earliest known ECM designs (Army 652-686
& 652-693 from 1941 [2, 3] and Navy 357428-357430 from 1944 [4]) required a minimum of 2 ft of earth cover.
However, no basis of design or calculations for these ECM designs have been found.
The following questions have been raised.
1. At what point does an ECM really behave like an AGM?
2. Is it possible that the quantity-distance requirements can be adjusted between the ECM requirements and the
AGM requirements by some sort of equation dependent on the actual earth-cover thickness?
In order to address these issues, the U.S. Army Engineer Research and Development Center (ERDC) and the U.S.
Army Engineering & Support Center, Huntsville (CEHNC) developed a series of experiments (code-named
MERCURY) to investigate the effect of varying earth-cover thickness for ECMs. MERCURY is an acronym for
Magazine EaRth Cover Update/Reassessment studY. Of particular interest to this effort is the point at which an ECM
