Africa Surveyors May-June issue 2023 digital

UXO SURVEYING
“Modern weapons are estimated to have a failure rate of 5%.
Depending on various factors, the failure rate can be up to 40%. Any
armed conflict in the world has created, creates, and will create the
same problem,” perceive Alexey Dobrovolskiy, Chief Technology Officer
at SPH Engineering.
Although UXO threat is increasing globally, however, survey
technologies and clearance methodologies are also improving in line
with this threat, allowing for faster, more accurate target identification,
environmentally conscientious clearance and the reduction of overall
risk to land-based and water-based site projects. Detecting land or
underwater UXO is complex and can require well designed surveys
with high sensitivity sensors.
"Unexploded ordnance pose significant risks to both human lives and
infrastructure development. Ground penetrating radar (GPR) can be
an effective tool for locating land-based UXO. GPR can detect objects
at various depths, ranging from a few centimeters to several meters,
depending on the specific equipment and soil conditions. GPR enables
survey teams to detect subsurface anomalies, such as munitions or
buried objects, in real-time without the need for excavation, enabling
faster and informed decision-making,” comments Allison Annan-Bujold,
GPR Product Management Director at Sensors & Software Inc.
Managing the process of UXO surveys is important and often involves
multiple stakeholders. It can be a costly and time-consuming task.
This is where a good workflow and commonly agreed data quality
factors are important. This can make it easier for project stakeholders
to understand how a survey will be conducted, and what data quality
thresholds are expected from the sensors used in order to detect a
given reference object. It also allows the team to spend more time on
data analysis, interpretation and reporting.
With reference to Stephen Wilson, Director of Business Development
& UXO Manager at EPI Group, “We always start with a UXO Threat
& Hazard Assessment. Covering the project site boundaries and
surrounding areas of influence, this is a desk-based study of the
UXO history in the area, describing the types, possible condition, and
density of UXO that may be present within an area of investigation,
where, and why. These potential UXO hazards are then risk assessed
against the planned project operations for their likelihood to cause
harm to people, plant, environment and species of concern. Only those
potential UXO that pose a risk need to be the subject of a UXO survey,
if there are no risks identified, no survey is required. This ensures the
UXO survey is specific to managing the actual project risks and that
the “As Low As Reasonably Practicable” safety methodology, is a viable
cost-effective solution that can be reached by all project developers.”
As multi-sensor datasets become increasingly large, a well-defined
workflow with commonly agreed data quality factors is essential to
improve the transparency of both land or water-based UXO surveys
and trust in their results. This will help to avoid miscommunications
between survey teams, clients and project managers that could lead to
expensive delays or even cancellation of a project.
“GPR systems can collect data over a large land area and map the
results," says Allison. "The software enables detailed data visualization,
interpretation, and integration with geospatial information systems
(GIS), aiding in the creation of UXO hazard maps that accurately
represent the land locations, depths, and sizes of potential UXO
targets. The mapping capability enables UXO detection teams to
prioritize and plan their clearance operations," she adds.
Importance of UXO Surveys
UXO is a major concern for a wide range of projects, from construction
and excavation to wind farm installations, oil exploration, offshore
oil & gas platforms and capital dredging. As a result, it is necessary
to plan and execute the survey to ensure that any potential hazards
are identified prior to any land or sea activities. Detection is the most
important aspect of any UXO survey. The aim is to locate, identify and
then remove any items that are a threat to any property or people
within an area. To achieve this, an expert survey team will need to
understand the local environment and the likely threats. This will
enable them to recommend the best possible detection method for
the site.
“UXO surveys are a key part of the management of UXO contamination,
management meaning normally to remove the contamination for land
release. There are different types of UXO surveys, and the process
would depend on the specific situation at different geographic
levels. Arguably the most important UXO survey is the Non-Technical
Survey (NTS) or desk top survey, normally conducted prior to any
planned encounter with UXO contamination, consisting of research
and interviews. This would determine areas of priority, non or less
contaminated areas, and the type of contamination, which in turn
would determine the type of detection equipment needed for ‘on-site’
survey to further confirm the findings of the NTS, and further clearance
techniques and technologies required,” remarks Steve Marner, Senior
Technical Delivery Manager at Artios Global Ltd.
According to Wolfgang Suess, Managing Director at SENSYS, the
importance of UXO surveys is manifold as buried UXOs in the ground
that are leaking over time. “Chemicals are a threat to our environment
and intact ammunition will lead to a lot of collateral damages and
injuries or deaths. In order to release mined or contaminated areas
to vitalize an economy especially in the areas of agriculture and
civil engineering, UXO surveys have to be done addressing 100%
of an area. For this kind of survey, an assigned expert will provide
(aerial) remote operated or man operated detection systems with
Magnetometers or electromagnetic sensors to detect all kind of bombs
and ammunition in that particular land area. Additionally, metal and
iron free plastic mines have to be detected by more specific devices
or in labor intensive man based ground surveys – which by far are
the most dangerous processes in demining,” expresses Wolfgang. “The
problem of UXO is not only a problem on land, but in the water as well.
Here again, leaking ammunition is harming our marine environment
such that, TNT (Trinitrotoluene) and other elements are found in water,
fishes and plants,” he adds.
“There are four general methods for performing a sea based UXO
survey. The two most common solutions are towed magnetometer/
gradiometer or ROV based gradiometer. In certain scenarios and
regions ROV based electromagnetic systems or 3D chirp systems
could also be used, however, this is a more uncommon approach. The
industry standard towed solution for large scale UXO campaigns today
uses one or several remotely operated towed vehicles (ROTV), with an
array of magnetometers or gradiometer,” acclaims Thomas Mennerdahl,
Technology Director Subsea at Reach Subsea AS.
www.africasurveyorsonline.com
May-June issue l 2023 13