For many decades, Open Burning/Open Detonation (OB/OD) has been used as a safe, effective, and economic way to demilitarize munitions for energetic material disposal. Field OB/OD air emissions have been difficult to characterize because of rapid dispersion, short event duration, heterogeneous emission concentrations, large plume lift, soil entrainment, and explosive safety restrictions. This project is a continuation of SERDP project WP-1672, which determined that an aerostat-lofted instrument sampling package called the “Flyer” appeared to be a feasible measurement platform for determining emission factors for the OB of propellants and the OD of explosives.
The objectives of this project were to:
- Provide innovative field scale measurement methods capable of obtaining representative air emission data and filling OB air emission factor data gaps.
- Conduct a field campaign to measure emissions of CO2, CO, PM10 and PM2.5, metals (e.g., Pb and Al), volatile organic compounds (VOCs), semi-volatile organic compounds (SVOCs), HCl, ClO3-, ClO4-, and other chlorinated compounds.
- Compile OB and static fire field emission factor data and develop the capability to measure emissions from field scale OB using single-, double-, and triple-based propellants and the static-firing of rocket motors containing aluminized ammonium perchlorate (AP) propellant.
In order to meet the objectives of this project, a field campaign was conducted to characterize air emissions from OB in pans of three propellants (M31A1E1, M26 and SPCF) and static firing of Sparrow rocket motors (containing AP composite propellant). The research team also studied the feasibility of using the Flyer to characterize air emissions from soil-covered OD.
During the field campaign, the Flyer was maneuvered into the OB and static fire plumes for sampling. The 46 lb (21 kg) instrument package was lofted with a helium-filled balloon of 16 ft (4.9 m) nominal diameter, maneuvered by two tethers connected to two vehicles. Continuous measurements of CO2 and CO, and batch samples for particulate matter (PM10 and PM2.5), metals, HCl, perchlorate, chlorate, VOCs, and SVOCs allowed determination of emission factors.
CO2 readings indicated that the Flyer was successfully maneuvered into 90-98% of the OB plumes from pan burning of the three different propellant types and 92% of the static firing plumes. The resulting emission factors for PM10 and PM2.5 were close, suggesting that OB plumes generate mostly fine PM (PM2.5). The calculated emission factors were compared to the first year results and literature values for similar propellant types. The derived emission factors for Pb and Ba from SPCF and M26, respectively, were in the same range as the Pb emission factor from the first year study of M1 propellant during SERDP project WP-1672. HCl was measured from the Sparrow rocket motor OB plumes with two different sampling methods, each resulting in comparable emission factors. The derived HCl emission factor was approximately ten times lower than found in the literature. Chlorate was also detected, but was close to the method reporting limit. No perchlorate and CO were detected for any of the propellants. Low levels of these emissions are expected with complete combustion of propellants.
Overall, the study was successful in determining the feasibility of the deployed measurement systems. The field campaign and its data analysis results clearly indicated that many of the deployed systems can become powerful tools to characterize air emissions from field OB operations.