The following case studies illustrates
the uses of the technologies employed in the services
we provide. Further information can be found in the our publications
for various international conferences.
EM-31 Survey of a large industrial
soil electrical conductivity (or resistivity) survey was used
to detect and plot areas within an industrial complex, which
were affected by chemical contamination.
Using this totally non-intrusive method meant that the affected
areas could be quickly and accurately defined. This (EM 31)
survey meant that the complete area, approximately 1000m by
450m, could be carried out and completed on-site in 3 days.
Soil samples were subsequently taken from the identified areas
for laboratory analysis to determine the precise nature of the
Using this technique represented a significant cost saving
for the client over the traditional multiple borehole investigation
of the whole site.
GPR survey of historic burial
penetrating radar has been used to successfully locate and plot
many different types of subsurface targets.
An example is plotting the layout of old unmarked
graves at cemeteries and Maori urupa sites. A burial site is
normally characterised by the void or uncompacted soil resulting
from the presence of the buried body and/or decomposed remains.
Some of the gravesites detected date back to the 1860’s
The radargram shows a typical distinctive response seen from
old burial sites.
Many hundreds of gravesites have been
found and plotted using this technique.
UXO survey using EM-61
This type of survey is used to
detect, both ferrous and non-ferrous, buried metal objects.
A typical example would be a survey to detect
and plot the location of buried UXO (unexploded ordnance). The
EM61 used for this type of survey is mounted on a small handcart,
which is pulled behind the operator along grid lines laid out
to cover the survey area.
example is a survey of an area near Manilla Airport which was
heavily bombed during WW2. Detected targets can be seen as the
red coloured anomalies on the adjacent plot of the surveyed
In a similar manner to the EM31 survey these
investigations area carried out at walking pace and can therefore
cover a large area during the course of a normal survey day.
shows a recovered ex military airborne bomb most likely from
the WW2 era.
Ground Penetrating Radar in
Ground penetrating radar can be used to detect
and plot a wide range of subsurface conditions including buried
This example shows a survey carried out over
the site of an old sawmill site. Buried waste material left
behind under the surface can create problems for later generations.
Gradually rotting buried organic matter can cause subsidence
problems and lead to ground instability.
In the example shown a long since buried
sawdust pit can be clearly seen as the circled dark homogenous
area on the radargram. The top of the pit is situated around
1.0 to 1.5m below the surface.
Ground Penetrating Radar in
Dropping levels of the local
water table caused a collapse in the soils underneath a concrete
floor slab at an industrial site. This in turn caused distortion
of the slab and a serious problem to operation of the plant.
Using non-intrusive Radar
the voids beneath the concrete slab could be detected and plotted.
A scaled layout drawing was then produced allowing repairs to
the voided areas to targeted and carried out with minimal disruption
to the concrete floor slab.
A detailed discussion can be
found in one of our publications