By meeting the demands of counter- improvised explosive device (C-IED) operations, the explosives industry has improved the design of explosives detection kits to include portability and easy use to avoid having to transport samples to a laboratory, which could delay results, says international independent consulting firm RA McClure.

“These improved explosives detection kits provide rapid and accurate trace detection of a variety of explosives in the field,” says presi- dent Robert McClure.

He adds that, when disposal personnel try to locate buried explosives, low-level trace detection can indicate when targeted explosives are in close vicinity, which means that recovery should proceed with caution.

At the 21st Annual BME Drilling and Blasting Conference, held at the CSIR Con- ference Centre in Pretoria, on November 7, McClure told delegates that improperly stored, discarded, deteriorating, misfired, stolen or surplus products are often the primary sources of explosives that require safe, expeditious disposal.

He further mentioned that only trained technicians with enough knowledge and experience should dispose of explosives.

“With complicated disposal operations, technicians are constantly challenged in today’s litigious society to safely carry out the task of rendering safe these types of explosives and devices, while reducing potential liabilities and meeting strict regulatory compliance,” McClure tells Mining Weekly.

He further notes that additional safety factors should be considered when disposing of explosives, depending on the type of explosive, its age, shelf life and level of decomposition.

He adds that, owing to recent develop- ments in C-IED and commercial blasting technologies, detection and disposal tools currently available to technicians have advanced significantly to help meet these challenges.

“These technologies have provided safer, more efficient ways to detect, investigate and dispose of commercial explosive products to reduce property damage and potential harm to disposal personnel and the general public,” says McClure.

During disposal operations, which include burning, detonation and countercharging, dilution and dissolving or chemical neutrali- sation, the detection and investigation process can be problematic. “Advanced systems and tools provide quick and accurate information to meet the challenge,” he says.

When hazardous devices of an unknown origin or composition require a risk assessment, X-ray systems can provide valuable images to determine safe handling and disposal.

Video cameras and closed-circuit television (CCTV) systems have greatly enhanced disposal safety. “Remotely operated CCTV provides coverage of hazardous operations while disposal personnel view footage from a safe location,” says McClure, adding that wired and wireless systems can be used, depending on the type of operation.

Meanwhile, McClure points out that lightning is a significant safety concern for any operation involving explosives. “Undetected, lightning can cause a premature detonation when unsuspecting crews do not have adequate time to prepare,” he says.

Lightning prediction and detection systems provide advanced notification of electrical charge build-up, thereby providing a safer operational work area.

“The explosives detected may be highly unstable and pose a danger to the handler, or it may not be possible to transport the explosives owing to public safety or for regulatory reasons. All these situations may require on-site disposal, including those sites near highly populated urban environments. A safety zone must be established and the site may require the temporary displacement of individuals from their home or workplace,” says McClure, adding that every effort must be made by the disposal operation to mitigate liabilities by controlling fumes, air overpressures, blast vibration and shrapnel.

Initiation Sources

McClure notes that, when handling explosives for disposal, it is important to understand that the characteristics of the explosive or initiation system may have changed from its original condition.

He adds that its sensitivity to initiation may increase significantly as a result of these influences, making the explosive vulnerable to premature detonation. “When planning disposal, certain energy sources, such as impact, friction, sparks, flames, shock, heat and electrical discharge, should be considered, he says.

“Incidents can occur as a result of explosives users failing to recognise that explosives should be disposed of or destroyed, rather than stored,” says McClure, adding that a lack of knowledge and supervision on explo- sion disposal sites also causes incidents.

He further mentions that the common causes of incidents at an explosion site, including poor working systems, people who fail to understand the properties and behaviour of explosives, as well as those who do not employ basic safety precautions, often arise from a failure to conduct suitable risk assessments.

Risk Assessment

A risk assessment is required to decide on the most suitable method of disposal. “The assessment needs to include the nature of the explosive and its hazards, the disposal method and the subsequent hazards created during the disposal process, as well as the location of the disposal site,” explains McClure.

He says that, when faced with a disposal operation, law enforcement, regulatory agencies and industry are often not equipped with the tools and systems to complete a disposal job safely.

“Often, people do not have the technical expertise to conduct close-proximity or large disposal operations, which require specialised services to reduce potential liabilities,” he says.

Emergency response and technical teams from RA McClure have employed these advanced technologies to conduct disposal operations safely. “Products, including mili- tary, speciality explosives for the oil and gas industry and commercial explosives for the mining industry, have been safely destroyed using these technologies,” says McClure.

He highlights two operations that were successfully completed using this technology. “In the first operation, a natural disaster created a safety concern, whereby explosives storage magazines were submerged under water during a hurricane.”

McClure explains that, owing to the volume of deteriorated products in this operation, disposal through quarry or construction blasts was not an option.

“The level of deterioration found in the initiation system prompted the regulatory agency not to transport any of the products, but to destroy them on site. There were several homes in close proximity, which was a concern. As a result, controlled countercharging was selected as the disposal method,” McClure says.

In the second operation, a document was discovered, which showed a borehole containing undetonated explosives in an oil and gas well.

“The site was secured and protected by frac tanks and fencing. A diverter, wellhead and blasting mats confined the borehole to protect the surrounding area from an unintentional detonation, while flushing systems provided the dilution of potentially unstable explosives and devices during the recovery operation,” he says.

Devices were removed from the borehole using application-specific overshot and grapple-fishing recovery tools, after which the recovered devices were identified to determine the hazard. “Once identified, various methods, such as burning, dilution and chemical neutralisation disposal, were used to destroy the recovered devices,” says McClure.