Underground Construction - November 2019 - 26

Harnessing Better Data to Embrace Defensive Digging
frequencies emitted by the system are
transmitted back, creating datasets that
can be saved, reviewed and post-processed
later. This can be done both before and
after a job has been completed.
The data that these GPR systems
compile gives contractors a clear picture
of any existing buried infrastructure,
miscellaneous objects or soil conditions
that could play key roles in the outcome

An example of 3D image created in postproduction by lining up multiple radar images
in sequential order to gain a more detailed
perspective of a surveyed area.

of the project. This information can then
be saved and shared digitally to provide
a common point-of-reference for any
interested party on or off-site.

Navigating soil conditions
Breaking ground is nothing new for underground construction, but the conditions of
the job-site soil can make a huge difference
when acquiring data for defensive digging.
The dielectric properties of the soil directly
impact a locating device's ability to get a
clear read of what's beneath the surface.
Common soil conditions that can affect
locating tools include the soil's material
composition, moisture content and density. For example, a dense, wet clay soil is
often more difficult for most tools to scan
through than clean and dry sand.
Well-made GPR systems have a way
to get around this common obstacle. A
high-quality antenna should be able to
auto-calibrate itself to prevailing soil conditions. This means less loss of signal, which
leads to a clearer set of data to reference.

Doing what other
locating tools cannot

Example of a screenshot created using a
GPS-integrated GPR system where a real-world
visual map is shown highlighting the presence
of a buried utility line.

Example of raw GPR data. Arch-shaped
hyperbola indicate the likely presence of buried
objects. The arches stacked vertically on the
right side of the screen indicate the possibility of
multiple objects stacked on top of one another.
The series of arches ascending from the bottomleft indicates a likely change in soil structure or
water table some distance beneath the surface.

NOVEMBER 2019 | UConOnline.com

Most traditional locating devices are
designed to only detect a specific type
of material or only scan to a certain,
often shallow, depth. When preparing
for trenching, directional drilling or
maintaining existing infrastructure, not
all tools will be effective. This is especially
true when locating non-conductive
objects. A device manufactured specifically

Data collected using a true, triple-frequency
GPR antenna will display three perspectives
- high, mid, and low-frequencies. The arch
shapes in the data indicate the likely presence
of a buried object. The operator can compare
these perspectives for a more detailed analysis
of findings.

for detecting metal pipe won't be able to
reveal if there is also clay pipe, poly lines
or fiber optic cables alongside.
Using GPR, however, the operator can
locate all conductive and non-conductive
objects. Each one is displayed as an
arch-shaped hyperbola on the screen. The
narrower and sharper the hyperbola, the
smaller the object. A high, slim arch is
more likely to be cable, whereas a broader
arch could be something similar to a buried
septic tank.

More efficient digging
environment
Like hydro or vacuum excavation systems,
sophisticated GPR systems do not require
digging or a complex setup process. You
only have to connect a battery, activate
the software, calibrate the antenna and
start scanning. This creates a more efficient
environment, where the locating team can
gather high-quality data without having to
engage in large-scale setup or teardown.
All you need to generate effective results
is some minor, low-intensity training and
your field knowledge.

Mapping for future
defensive digging
With the right GPR system, the operator
can post-process the scan data into sharp,
dynamic visual representations. Whether
that is creating a 3D model or mapping
findings on a GPS-integrated application,
the data can translate into a format that
allows for easier understanding and more
actionable decision-making.
Should the contracting team ever have
to return to that same site for maintenance
or new installation, there is a common
reference point that all team members can
implement for safer and more efficient
operations. This cuts down prep time and
eliminates uncertainty by informing the
team where buried objects are located
before any ground is broken.
Data is everywhere. Using the right
subsurface locating system, it can be used
to help protect and prosper underground
construction professionals. It's time to
start harnessing it more effectively to
maximize efficiency and reduce risk. *
For More Information:
US Radar Inc., (732) 566-2035, usradar.com

http://www.usradar.com http://www.UConOnline.com

Underground Construction - November 2019

Table of Contents for the Digital Edition of Underground Construction - November 2019