Comparison of Quantity-Distance Standards for Earth-Covered Magazines in
Various National/International Manuals
David D. Bogosian
1
& Jon Chrostowski
2
1
Baker Engineering and Risk Consultants, Inc.
2
ACTA, Inc.
360 N. Pacific Coast Hwy., Suite 1090 2790 Skypark Drive, Suite 310
El Segundo, CA 90245, USA Torrance, CA 90505, USA
dbogosian@bakerrisk.com chrostowski@actainc.com
Keywords: earth-covered magazine, igloo, separation distance, IMD, standards
ABSTRACT
National and multi-national agencies tasked with regulation of explosives storage have produced a number of different
manuals governing the maximum amounts of HD 1.1 material that can be stored in an earth-covered magazine (ECM).
These quantity-distance (Q-D) requirements are set forth in prescriptive language in manuals published for use by the
engineering and planning community.
A recent comprehensive review of five such manual sources resulted in a compilation of a set of comparative tables
in which the requirements for minimum separation distance, as well as for blast loading on various elements of the
ECM, were outlined side by side. The five manuals represent requirements for the United Kingdom, Canada, and
U.S.A., as well as multi-national entities such as NATO and the United Nations. All manuals use the same designations
for categories of ECMs (namely, 7-bar, 3-bar, or undefined). But the actual requirements, both in terms of scaled
distances and the applied loading (pressure and impulse), are not entirely consistent across the various requirements.
This paper identifies some of those inconsistencies, as well as potential inconsistencies in the correlation between
separation distance and its corresponding pressure and impulse.
BACKGROUND
In early 2017, BakerRisk was engaged by the Department of National Defence, Canada, to evaluate their long-span
earth covered magazine (ECM) design for blast loads from an accidental detonation in an adjacent magazine. The
study was a comprehensive one involving high-fidelity finite element models of structural response as well as the
latest analytical estimates of blast loads from ECMs. That study is documented in a separate paper [1], as well as a
fully detailed technical report [2].
In the course of that study, the authors were tasked to review a broad range of national and international safety
standards for storage of ammunition, particularly as they related to design requirements for siting of ECMs. Five such
standards were identified representing the US, UK, UN, NATO, and Canadian requirements. All are formulated in
terms of quantity-distance (Q-D), and so they all provide minimum separation distances; in addition, most provide at
least some design loads (pressure and impulse) that ECMs must satisfy in order to qualify for one of three different
standard ratings, depending on the load that the headwall of the ECM is designed to resist:
7-bar
3-bar
Undefined
