Open burn and open detonation (OB/OD) operations are used to destroy excess, obsolete, or unserviceable munitions and energetic materials. Detonation of energetic materials produces a wide range of air and surface pollutants, including carbon monoxide, nitrogen oxides, volatile organic compounds, acid gases, and particulate matter. These emissions, including un-decomposed or partially decomposed energetic materials, may lead to atmospheric pollution or groundwater contamination. The speciation and amounts of these emitted pollutants depend on the identity and amount of energetic material detonated, the detonation order, the detonation mode (air burst, surface detonation, buried detonation), and the munitions type (shell, mine, detonation charge, etc.). To determine whether U.S. military training or munitions disposal activities produce emissions that threaten air or groundwater quality, reliable estimates of emission factors must be available for a representative fraction of the thousands of munitions types in the inventory. A variety of detonation experiments, including detonation chamber tests, and open-air field detonations have yielded increasingly rich data sets of measured gaseous and particulate emissions factors from a range of energetic materials deployed as both unconfined charges and standard munitions.

Leveraging these data sets, the objective of this project was to develop a detonation source characterization model (SCM) for predicting emissions across munitions classes and detonation modes.

The detonation SCM is composed of a number of coordinated sub-models. These sub-models predict the chemical content of the detonation fireball, compute the mass of fireball entrained soil particles, estimate the amount of shock ablated energetic material that escapes beyond the fireball, model the entrainment of atmospheric oxygen mixed into the fireball and the subsequent afterburning effects on the chemical content of the detonation plume, predict the chemical interactions among both gas phase pollutants and soot and dirt particles in the plume, calculate the deposition pattern of larger plume entrained particles back to the surface, and predict the buoyant rise of the plume gases and entrained fine particles.

The detonation SCM has been validated with pollutant emission factor data obtained for a range of munitions and demolition charges obtained in an ongoing series of detonation tests managed by the U.S. Army Environmental Center. After validation against a sufficient range of diverse munitions and explosives, the SCM can be used to predict emissions factors for as yet unmeasured types of munitions. SCM predicted emissions factors can be used as inputs for traditional atmospheric dispersion or soil and groundwater transport models that may be used by environmental scientists and engineers to predict the impact of military training, weapons testing, or munitions disposal activities on military facilities and surrounding regions.

The detonation SCM can be used to predict the release, chemical transformations, deposition, and dispersion of emissions from high energy detonation of munitions and explosive charges. It incorporates a number of detailed microphysical processes that are important in understanding munition emission factors and the potential environmental impact. Of particular interest relative to previous models are the sub-models for crater dynamics, afterburning chemistry, and the impact of detonation plume vortex structure of particle deposition. Data analysis and model validation studies to date indicate that the model holds promise as a numerical tool for understanding detonation emissions and supporting environmental impact assessments at Department of Defense test and training sites.