International Explosives Safety Symposium
San Diego, California, August 2018
1
An Overview of Risk-Based Explosives Safety Siting
Jon Chrostowski & Ryan Schnalzer; ACTA; Torrance, California, USA
Michael Oesterle Ph.D., P.E. & Ruby Domingo; NAVFAC EXWC; Port Hueneme, California, USA.
Keywords: risk-based explosive safety siting, ESS, RBESS, hazard/consequence analysis
ABSTRACT
A recent effort has been completed to incorporate hazard-consequence analysis tools into the Explosives Safety Siting
(ESS) software as Risk-Based ESS (RBESS). ESS is an automated site planning tool developed by the Naval Facilities
Engineering and Expeditionary Warfare Center (NAVFAC EXWC) and funded by the Department of Defense
Explosives Safety Board (DDESB). The Department of Defense (DoD) has mandated the use of Automated Site
Planning (ASP) by the military services for siting all facilities that store and handle explosives (i.e. potential explosion
sites (PES’s)). All DoD ammunition and explosives facilities around the world must be approved by the DDESB to
ensure they present an acceptable level of risk to DoD personnel, assets and mission, as well as to the public. For
situations when facilities cannot meet the DoD criteria the tools that are available in RBESS generate data on the
consequences from an accidental explosion and are used to provide the proper acceptance authority with information
required to assume risk for un-sited PES’s. There are two tiers currently available in RBESS to perform a hazard-
consequence analysis; RBESS Tier 1 and 2a. The Tier 1 tool is a qualitative risk management analysis that requires
little to no additional input from a user beyond typical information required for an ESS analysis. The analysis uses
hazard zones that correspond to explosives safety quantity-distances (QD) (i.e. intermagazine distance, intraline
distance, inhabited building distance, etc.) to estimate consequences in terms of facility replacement cost, fatalities,
and injuries. The Tier 2a tool is a qualitative risk analysis tool that calculates hazards and consequences based on the
combination of methods and algorithms in DDESB Technical Paper (TP) 14 Revision 4 and TP-23. Most of the input
required to run RBESS Tier 2a can be read from an existing ESS dataset, such as number of occupants and replacement
cost, but some additional input is required to determine event probability; PES category, soil type, and more. Both
RBESS Tier 1 and Tier 2a have been developed to generate risk information for a single PES that affects multiple
exposed sites (ES’s). The output for both Tier 1 and Tier 2a RBESS include color-coded maps that display information
on replacement cost, fatalities, and injuries. The output also displays consequence information for individual ES’s as
well as summary information for all the ES’s affected by the PES. Both tiers of RBESS automatically populate the
Department of Army (DA) Form 7632 which is known as the Deviation Approval and Risk Acceptance Document
(DARAD). RBESS is being released in ESS v6.1.4 and will be available to ESS users in the near future.
INTRODUCTION
A recent effort is near completion to incorporate hazard-consequence analysis tools into the DDESB funded ASP
software tool ESS. The implementation of these hazard-consequence tools into ESS is referred to as RBESS. The
development of RBESS has been accomplished by NAVFAC EXWC with their support contractors VSolvit and
ACTA, under the direction of DDESB and the military service component representatives of the automated site
planning working group and ESS configuration control board.
All organizations and military services that manage and operate DoD ammunition and explosives (A/E) facilities must
comply with DoD requirements and regulations that are published in DoD 6055.09-M, “Ammunition and Explosives
Safety Standards [1].” DoD 6055.09-M includes criteria for QD separation distances that are required between PES’s
and ES’s. The DDESB is the approval authority for DoD explosives sites and grants authority for operation through a
formal process that requires installation planners to prepare individual Site Approval Request (SAR) packages for a
PES. This approval process is supported by military component explosives safety approval authorities, who have the
authority to impose additional requirements over-and-above the DoD requirements. The DDESB will not approve
SAR packages for facilities that do not meet QD separation distances because the risk associated with these deviations
exceeds the risk commensurate with that of the DoD explosives safety regulations.
A common deviation or violation of QD criteria occurs when the required PES to ES separation distance exceeds the
actual separation distance. Multiple measures exist to address QD violations, including compensatory measures,
engineering analysis, DDESB approved risk-based explosives safety (i.e. SAFER, [2]) siting. Risk acceptance of a
QD violation occurs when a military service component assumes the risk that a QD violation imposes on the related
mission, operations, facilities, and people at the site. The level at which a risk acceptance occurs is governed by
military service component regulations and policies. Depending on the service component, required risk acceptance
