Watch our webinar where we will discuss industry best practices to accurately and cost-effectively detect and analyse UXO.
This webinar covers:
– An overview of common challenges faced when trying to locate UXO
– How to overcome these challenges, reduce time and costs, and enhance detection accuracy
Director, Segment Business Development – Seequent
(soft intro music)
<v Lorraine>Hello, everyone.</v>
I’d like to welcome you to today’s webinar
on industry best practices
for unexploded ordnance detection and analysis.
My name is Lorraine Godwin.
I’m the Global Business Director
for Seequent’s near surface and marine division.
Unexploded ordnance detection can be expensive, risky,
and time consuming to find and locate,
and excavation costs can quickly add up,
but there are industry best practices,
which we’re going to be talking about today.
All right, before I introduce our speaker,
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Seequent create powerful geoscience analysis
and 3D modeling software
that allows for integration of different geo datasets
to understand the subsurface of the earth.
The company was originally founded in the early 2000s,
born out of medical 3D imaging technology,
which in 2004 was applied to understanding
geological science and the subsurface of the earth.
These geo datasets are used to find mineral resources,
for looking at infrastructure and construction projects,
understanding the geo-technical properties,
oil and gas deposits, geothermal, natural hazards,
and looking for water resources.
Today, we’re a team of over 350 people
that includes geo scientists, engineers, researchers.
Our head office is in New Zealand
and we have 18 locations around the world.
The vision of the company
is to enable better decisions about earth,
environment and energy challenges using geo data
to understand the subsurface of the earth.
Today, we are focusing on
Seequent’s geo-physical solution platform
called Oasis montaj.
Oasis montaj is a powerful geoscience platform
for analyzing and interpreting geophysical data
and integrating it with other types of bore hole,
drill hole and geochemical data.
It’s been applied for unexploded ordnance detection
for over 30 years.
I am going to be your host for today,
and our speaker is Laura Quigley.
Laura Quigley is the technical analyst
with our near surface and marine division.
She received her Bachelor of Science degree in Geophysics
from Memorial University in Newfoundland
and her Master’s of Science degree in Geophysics
from the University of Toronto.
Her professional career started with
Fugro Airborne Surveys,
where she would process
and interpret airborne geophysical data.
She then worked for a marine seismic company
where she participated in a large number of research cruises
After completing her master’s degree in 2013,
Laura moved to Australia
and worked in a research environment
with various universities in Brisbane.
She worked for the University of Queensland
on seismic projects
for unconventional coal seam gas development,
and then moved to Queensland University of Technology
where she spent several years researching
geo dynamical processes through analog modeling.
Laura returned to Canada in January, 2020
to join Seequent as our Technical Analyst
with our new surface and marine team.
Please welcome Laura Quigley.
<v Laura>Great. Thanks Lorraine.</v>
and welcome to this webinar about industry best practices
for UXO detection and analysis.
Why digital geophysical methods
are best for identifying UXO.
So an agenda of the webinar today is as follows.
I’m going to talk about what are UXO.
Why are they a problem.
Methods of detecting UXO,
and pros and cons of each method.
And then finally, some Oasis montaj solutions for UXO.
So what are UXO?
UXO stands for unexploded ordnance.
Other acronyms referring to the same thing
include UXB for unexploded bombs,
ERW for explosive remanence of war,
MEC for munitions or equipment of concern.
So all these acronyms refer to explosive weapons
that did not explode and still pose a threat of detonation.
So UXO is a global problem.
More than 80 countries are affected by UXO.
So this map highlights the number of UXO casualties
around the world with red being the most extreme.
Most of the UXOs are from past wars.
So World War I and World War II over 70 years ago.
Also more recent conflicts in certain parts of the world,
such as Vietnam, Laos, and Cambodia,
which were heavily bombed during the Vietnam War
in the 60s and 70s are highly contaminated by UXOs today.
In the UK alone,
there were still tens of thousands of tons of explosives,
which did not detonate from World War II.
And unlike parts of Europe and Asia,
UXO problem in the US
mainly comes from previous military testing sites
as opposed to world wars or other wars.
And also, UXO can be located onshore and offshore.
So why are UXO a problem?
So today, UXO from recent conflicts, legacy wars
and old military training sites
still kill and injure thousands of people.
Often rural farmers have no choice, but to farm land,
which is contaminated by UXOs.
15 to 20,000 people a year are injured or killed,
and approximately 80% of those are civilians.
Another reason UXO are a problem
is because of the environmental hazard.
So environmental contamination.
For example, TNT was an important military explosive.
Red water associated with TNT pollution
is toxic to the environment
and is considered hazardous waste.
Also, many UXO still remain on the sea floor.
So this is a problem for fishing, oil and gas,
So the risk of detonation,
as well as chemicals leaching into the ocean.
And finally, infrastructure and community growth
is affected by UXOs.
So cities cannot expand and grow
without UXO remediation and removal.
Previous military sites, for example, in the US
which were located in the middle of nowhere
during war times are now encroaching upon
areas that are being developed for residential
or business uses.
And this is a danger for both onshore
and offshore construction and excavation work.
Okay, next I’m going to show you some examples
of how UXO are affecting the communities today.
This is an onshore example.
So this is a recent airport closure in Germany.
Germany was heavily bombed during World War II.
So thousands of UXO from World War II
are uncovered each year in Germany.
In this particular instance,
a 450 kilogram bomb
was located on the outskirts of the city.
And this picture shows travelers
waiting outside the Hamburg Airports in 2017
while bomb disposal experts defuse this bomb.
This also resulted in evacuation of 300 homes in the area.
And now I’m going to show you an offshore example.
So this picture here shows the mast of a US cargo ship.
It sank in 1944 off the coast of UK.
So this is the SS Richard Montgomery.
It was carrying tens of tons of munitions
and they sank with the ship.
And all are still onboard today,
which is actually only 15 meters below the sea surface.
So it’s constantly monitors.
However, the removal of the munitions is just too complex
and dangerous at this point.
So who’s involved in the cleanup?
So much effort is
and continues to be put into UXO remediation.
It is not easy.
It’s often difficult to locate UXO and manage them,
and very costly to remove.
So due to these risks,
the removal is a joint effort between government agencies,
private companies, contractors,
as well as humanitarian groups.
So humanitarian groups include MAG and the HALO Trust,
and these groups work in developing countries
to help give the land back to the people.
So they clear land for agricultural development
and community purposes.
In the US, the Department of Defense
and the US Army Corps of Engineers
are responsible for clearing formerly used defense sites,
and various other private organizations and contractors
work around the world on UXO projects.
Okay, so now I’m going to talk about
methods for UXO detection,
both analog methods and digital geophysical methods.
So analog also known as mag and flag
involves hand-held metal detectors.
These metal detectors have been used for centuries
to find treasures.
So operators walk along the ground,
moving the instrument from side to side.
And when they either hear or see a signal,
they place a small pin flag in the ground,
and this signal is from passing over a metallic object.
So this results in a large number of flags,
all which have to be dug as it is unknown
what is associated with each flag.
Okay, so digital geophysical methods.
I’m going to show you some examples.
So for digital geophysics,
the two primary techniques are electromagnetic induction
Data is digitally stored on a computer system.
So these two onshore systems shown here.
The one on the left is an electromagnetic conduction system.
It uses transmitter and receiver coils.
So a transmitter coil sends a signal into the ground,
and when it encounters a metallic object,
a secondary signal is generated
and this secondary signal is picked up by receiver coils.
So this method is an active method,
meaning you can send a signal into the ground
and it detects any metallic objects,
so ferrous or non-ferrous.
On the right, we have a magnetic sensor.
So this is a passive method.
It’s a method that detects any changes
in the earth’s magnetic fields.
So this works well for ferrous objects.
So any object that contains a high concentration of iron.
A lot of UXO have steel casing.
So this method works particularly well.
Okay, so now I’m going to show you some systems
for digital geophysics offshore.
So the same principles apply.
We have electromagnetic induction on this slide.
This is an EM61 sensor
that is now designed for offshore surveying.
So this is a fairly recent technology.
And magnetic sensors.
So these have been used offshore for a number of years
to do offshore surveying.
So this is a single sensor on the left,
a marine magnetometer,
and two sensors shown on the right.
So this is gradiometry mode for surveying.
This is easy to tow behind ships,
and you can tow just meters above the sea floor.
Another way of collecting UXO survey data
is using drones or UAVs.
So this picture here on the left shows the mag arrow,
so a magnetic sensor being operated by a drone,
and the picture on the right shows another system
known as the drone mag.
So this is a good option
for when the terrain is often difficult to walk.
And it can produce quite a dense dataset.
So with airborne surveys, line spacing is often 100 meters,
where with drones, you can get line spacing
down to just a few meters.
Okay, so advanced classification.
This is the latest digital geophysical method
for UXO surveying.
It involves electromagnetic induction, as I spoke of before,
the difference being it uses multiple receiver
and multiple transmitter coils at different orientations.
So a large number of information is collected
at each data point,
and this information can provide
the necessary properties of the target
that can distinguish it as a UXO or non-UXO.
So it has the ability to actually classify your targets.
And this is done based on prior knowledge of UXO signals
that have been recorded.
Okay, so now I’m going to talk about
the advantages and disadvantages of each method.
So I’ve listed on the left, mag and flag disadvantages
and on the right, geophysical method advantages.
So on the left.
So for mag and flag, data is not recorded,
and with digital geophysical methods,
you have all your data recorded as well as geo-referenced.
So you have GPS data along with all your geophysical data.
And mag and flag is very influenced by the operator.
So system sensitivity can be turned up or down.
Signals can be missed either audio or visual signals
and operator keys in the pocket or cell phones
can interfere with the signal.
And with digital geophysical methods,
you can have an audit trail of your data.
So because all the data is recorded,
you can go back and analyze it later
to see if your survey coverage was 100%,
make sure all the instruments were working, all the sensors.
So magnetic soils tend to cover up signals, UXO signals,
where they exist.
So digital geophysics can allow you to process
the effect of the magnetic soils from your data,
as well as any background geology effects can be removed.
So this leaves just your UXO signal clear in the data.
Mag and flag has a high false alarm rate.
So that means the number of targets flagged
versus the number of UXOs discovered is very high.
And with digital geophysics,
we’re able to characterize and often classify targets.
So this reduces the number of false alarm rates,
so reducing the digs.
And mag and flag,
you cannot reference flag locations to any other data.
With digital geophysics, each data point is geo-referenced.
So you can bring in other maps,
such as other geophysical maps or geological maps
to help with your interpretation.
Mag and flag is relatively inefficient
as it can scan smaller areas of land at a time,
and digital geophysics allows for dense datasets.
And then finally, for mag and flag,
every target needs to be dug
and digital geophysics allows one to compile a dig list
based on data analysis.
Okay, so now I’m going to talk about the way forward.
So costs associated with UXO detection and removal.
So this graph highlights some of the costs associated
with detection and removal.
Site assessment, survey mapping,
vegetation removal, scrap metal removal,
and UXO removal and disposal.
So as we can see,
a vast majority of the costs
are associated with digging up scrap metals,
so non-UXO targets.
So there’s often thousands of targets on a site,
which are identified for digging,
and each dig can cost between about 35 and 100 euros.
So costs add up really quickly.
And it’s been shown that advanced geophysical techniques
have stopped excavation of non-UXO targets by up to 90%.
And this money can be used on other projects,
other UXO projects.
So false positive ratio: Mag and flag.
It’s 100:1 on average.
So that is 100 digs that were non-UXO
to every one UXO discovered.
And with digital geophysical methods,
this ratio reduces to 10:1.
Okay, so now I’m going to go into our Oasis montaj software
and just show you some tools you can use for UXO processing
of digital geophysical data.
So I’ve created a project and it’s called single mag,
and I’m going to show you a Marine Magnetic survey
off the coast of Hawaii, just some sample data.
And I’m going to show you a lot of the processing
that we can do in this particular workflow
of UXO marine mag.
So I can import my data
and it gets imported into a database.
I’ll call the database, single mag_2.
And then you can locate your survey file,
which is a CSV for this particular survey.
And then I create a template for the imports.
And on the last step of the import,
I can tell which channels are line channel.
So this way the survey data is split on the line channel
and in the rest of the columns are channels or data type.
Okay, so now I have my data in a database,
and it’s very similar to an Excel spreadsheet.
However, I’m going to geo-reference my data now
so it knows which coordinate system it’s in.
And this is projected X, Y.
And its UTM zone for North for Hawaii.
And then click okay,
and now your data is geo-referenced
and you can see in the bottom
which coordinate system your data is in.
So we can see all the survey lines
if we right click on the top left cell.
There’s 57 lines in the survey.
We can scroll through them.
And I’m just going to show you a database view
where we use our profile windows,
which are available here.
And I have a view that’s been set up.
So this is a good way to check all your data.
I have X channel displayed on top,
then the Y channel, then the magnetics channel,
and the altitude on bottom.
And I can scroll through my lines and check for any errors,
any dropouts, any spikes.
So now I’m going to show you how to correct for the X and Y,
which is the GPS positions.
Any spikes, any dropouts, any errors in the GPS.
So we go to UXO marine mag and we do a path correction.
I just tell it which database to look in,
and it’ll create a backup of my X and Ys.
And then I click, okay.
This also produces a map
and the map shows you your survey coverage,
which is a really great tool.
Okay, so here’s my survey lines with the corrected GPS data,
X and Y data.
And we can overlay some aerial imagery
using our seek data, add bing imagery tool.
So this aerial data is just a really good way
to interpret your data
to see if the coverage was where you thought it was.
However, it doesn’t export with any final products.
Okay, so we see our survey was in the marine environment.
There’s some man-made structures.
So there’s a dock and it was off the coast of Hawaii.
Okay, so now I’m going to close this.
And I can always come back to it
if I wanted to use it for interpretation purposes.
Next, I’m going to show you some magnetics data,
which I’ve processed.
And I’m going to use a different database that I’ve worked on.
So that’s the same data just with some processing done.
So in the UXO marine mag menu,
we can process data for altimeter corrections,
and we can also model the background’s magnetic fields,
which we can then remove from our data.
So the top profile window here shows the magnetics
before and after an altitude correction.
So before the altitude correction is the blue curve
and after is the red curve.
In the middle profile I’ve shown the altimeter.
And this is just a good way to see
if our data correction did what we thought it should do.
So it’s actually, the altimeter is slightly higher here.
So it’s actually brought my anomaly up a bit.
And the bottom profile we’re now showing here
is just the magnetics data with a modeled background field
shown in green.
So we can use this modeled background fields
to subtract from our magnetics data,
leaving just the anomalies of interest.
And all this was done in the data corrections tool.
Okay, so that’s my data in profile view.
Next, I’m going to talk about grids.
So we can grid our data.
So this interpolates the magnetics
or anything we choose to grid between survey lines.
And I’m going to show you my grids on a map.
So you can drag any of these grids onto a map window.
It’s just a nice way to display your data.
You get a North arrow, scale bar and you can add a title.
So I’m going to show you.
This is the magnetics data I processed.
I can also bring out my survey path.
And you can see it’s a bit hard to interpret
for any UXO targets.
You see highs and lows.
So the highs are red, the lows are blue.
However, we have a tool within Oasis
that allows us to calculate an analytical signal.
So that’s under UXO marine mag.
And it’s done here.
Using the analytical signal is a great way to pick targets.
So I’m going to show you that.
So I’ve gridded my analytical signal.
It’s the same data.
However, now we have our targets as positive values.
So the red blobs on the map are all high magnetic values.
And it’s a good way to pick targets.
It’s much easier to visualize your targets this way as well.
So within this workflow, we can also pick targets.
We can pick them manually or automatically from the grid
that I’ve shown here.
We can also pick them manually or automatically
from our profile view.
So I’ve picked my targets automatically from a grid.
And when you pick your targets,
a target database will be created.
So this target database is great
’cause it can serve as a dig list
you can give to any clients you’re working for
or anyone who wants to know the coordinates
of where the potential UXO targets are.
So you have a target ID plus your X and Y,
and an analytical signal value.
Okay, so I’m just going to now show you those targets
that I’ve picked.
I can display them as symbols on my map.
And if I zoom in,
you can see all my targets is yellow crosses on the map.
Another great way to visualize your data,
and you can also go in and further edit these targets.
So I can manage my target list.
And then I can do that based on what I see here.
So I can actually click and delete,
draw a polygon around a bunch of targets
and tell them to merge.
And, okay, so finally, I want to show you
that we can invert each target for size and depth,
and that is done in our UXO marine mag tool as well.
So we have a couple of different options here.
We have the Euler deconvolution,
we have batch (indistinct) queue.
So these are various ways to model targets
for size and depth.
And finally, I’m going to show you a 3D view
of some target depths that I’ve modeled.
So I’m just going to open a view here.
And just so you know,
I’ve exaggerated these depths
for the purpose of this webinar
just to show you what they can look like in a 3D view.
So we have my analytical signal on top
with the targets as black Xs,
and then the target depths modeled here
with the pink circles.
Again, this is exaggerated depths,
but this is something you can do.
And you can export this as a PDF file.
Okay. Now I just want to make a few concluding remarks.
So digital geophysical methods reduce dig costs.
They increase UXO detection,
so fewer UXO are left in the ground
and this ultimately saves lives.
<v Lorraine>Thank you, Laura.</v>
We’ll now take questions from the audience
at the end,
and several have come in over the GoTo webinar.
So please keep those coming.
And we’ll do our best to get to them,
and if we can’t,
we’ll follow up with answers afterwards.
So Laura, I’ve got a question here.
“How do you determine which geophysical method
is best for your survey?”
<v Laura>Okay, so whether you choose</v>
or magnetic techniques depends on several factors.
You want to consider the ground type
and the likelihood of UXOs being in the area,
and the potential depth of your targets
needs to be considered
as well as the use of the sites after the survey.
So for magnetic sensors,
they’re very sensitive.
So you can detect very low signals.
However, electro-magnetic sensors
detect both ferrous and non-ferrous metals.
And electromagnetic techniques
don’t see quite as deep as magnetic sensors.
So with electromagnetic techniques,
you can do advanced classification
so you can determine if your target is a UXO or not.
<v Lorraine>I’ve got another one here.</v>
“How can one best design a UXO survey
for geophysical methods
in terms of data coverage and processing?”
<v Laura>Okay. So UXO surveys</v>
require a large number of data points
for accurate interpretation.
It is recommended that a grid be used
so you outline your survey sites using your grids,
and you often run lines
parallel to the longest dimension of this grid.
Line spacing is pretty small.
So maybe two meter line spacing for UXO surveys.
And then you can also collect tie lines.
So lines perpendicular to your survey lines. (clears throat)
This will help with data processing
and they can be about 10 to 20 times
the survey line spacing.
So this will provide more information about targets
which are parallel to survey lines as well.
Another question is,
“What are leveling and instrument drift corrections?
And should I be concerned with them
when I’m conducting a UXO survey?”
<v Laura>Yes. So geophysical instruments are not perfect,</v>
and as with all electrical systems,
they will drift and also have directional influence.
So drift corrections occur
when a zero condition
is no longer reading zero on your instrument.
So this is an offsets and it can be a small percent,
but it’s usually important
when you’re looking for small targets such as UXO.
And then tie lines are useful,
tie lines which I just mentioned,
they’re useful for applying leveling corrections.
So you can level your data for any drift that does occur.
You’ll have two data points at the same spatial location.
Magnetometers often exhibits directional differences.
So depending on which way you’re surveying,
you can apply a heading correction.
So instrument lag tests can also be run.
So this determines the inherent latency in an instrument,
and this can be applied to your data.
<v Lorraine>Okay. Thank you, Laura.</v>
Laura, we have another question.
“If I’m working with someone who doesn’t have Oasis montaj,
can I still share my maps and dig lists with them?”
<v Laura>Yes. That’s a great question.</v>
I can show you our webpage where you can do that.
So if I just open my browser
I can show you our free viewer.
So you can easily download Geosoft free Viewer,
and this way you can look at Geosoft files,
you can import and export files,
and you can view files of different formats
and convert between file formats.
It also allows you to print maps.
So if you’re working with anyone that you need to give maps
or dig lists to, or any sort of grids,
you can do this and they can easily view them
and export them.
Wait, we have another question.
You showed a lot of systems in your presentation,
which of these are available commercially?
<v Laura>So magnetometers and electromagnetic sensors</v>
have been available commercially for a number of years
by a number of manufacturers.
They can be purchased as individual sensors
or in a small selection of prefabricated arrays,
or it can be built into more complex arrays
by individual survey contractors to meet specific needs.
So providers include Geometrics, Geonics, Gym Systems
and Marine Magnetics,
and advanced DM sensors capable of collecting data
to facilitate classification of UXO targets,
include MetalMapper, which is from Geometrics,
and it’s now commercially available.
<v Lorraine>Great. Thanks, Laura.</v>
All right, we have another question on,
“How is interference removed in high density, metallic areas
to determine which are UXO versus debris?
At my sites, we’ve had no success with this method,
especially around buildings.”
<v Laura>So all sensors</v>
are subject to some degree of interference,
from buildings or fences or other nearby cultural effects.
In general, EM sensors are less impacted
than magnetic sensors.
And with advanced electromagnetic sensors,
it is also possible to use a portion of the data
to reduce the impact
that a thin surface layer of metallic debris
or metallic soil will have on your final interpretations.
<v Lorraine>Great. Thanks, Laura.</v>
All right, I think we have time for one last question
and there are ones that we didn’t get to
we’ll send answers by email to those.
So thank you for all your questions today.
Our final question is
“Which methods are the US Army Corps using
on their UXO sites?”
And that’s a great one.
So the US Army Corps had been using magnetics originally
and then they did switch to electromagnetics over time
because they found that electromagnetic sensors
could give so much more information about the target below
as Laura pointed out earlier in the presentation.
In today’s projects,
they are requesting for their contractors to use
advanced geophysical classification methods
using advanced sensors like the MetalMapper 2×2
And the reason for this
is because it reduces the excavation costs
of unexploded ordnance by such a large amount.
Going back to what Laura was talking about,
that 10:1 factor.
It gets your digs down to that kind of a ratio
versus 100:1 or higher.
And so on all of their projects today,
they are requesting that
advanced geophysical classification methods be used
unless there’s a reason that it can’t
for terrain or accessibility reasons.
So thanks for that question. That was a great one.
All right, I’d like to thank everyone
for joining us for today’s webinar,
and I’d like to thank Laura for being our presenter today.
Our contact information is up on screen,
and we do encourage you to reach out to us
if you have any questions.
And as mentioned, we have recorded today’s session.
The recording will be sent out to all of the participants
and anyone who registered for this webinar.
And any of the questions that we didn’t get to,
we will answer those and send our responses by email
Thank you for joining us today, once again,
and we hope that during this difficult time in the world,
that your families and yourself
are keeping safe and healthy.