Geosynthetics October/November 2022 - 23

industry standard would have required
70 destructive samples.
The Demtech equipment allows the
welding technician to input the seaming
data so the weld/seam number can be customized
at the time of installation instead
of requiring post-processing by the CQA
firm. ESI marked the liner with paint each
time a welding tolerance was exceeded,
which simplified identifying and visually
evaluating locations with parameters outside
of specified tolerances. In addition,
an exception report was produced that
only identified out-of-tolerance areas for
the day's installation instead of reporting
all data for each seam. The reporting can
be adjusted to provide all data for each
seam, but the project specification and
regulatory reporting requirements did not
dictate showing all data. ESI transmitted
DAW reports electronically to CQA personnel
in portable document format (.pdf)
at the end of each installation day.
The seam weld report is a multipage
report produced for each seam where a
welding parameter exceeded tolerances.
The first section contained project information,
welding machine make/serial
number, seam number, seam start and
end times, and the set and measured temperature,
speed, and joining force (referred
to as pressure) at the seam start and end
times. The second section contained seam
data, which showed a graphical representation
of the seam for each parameter
followed by a seam detail report providing
all out-of-tolerance parameters and their
location on the seam.
Data and quality-based
geomembrane seaming-
evaluation
Wood Environment & Infrastructure
CQA personnel reviewed DAW reports
in conjunction with non-destructive
seam test results and field observations.
Fusion seams were non-destructively
FIGURE 5 Site 2 processing pad (note residue on new installation in highlighted area)
tested using the air-channel method
(ASTM D5820) consistent with standard
practices and technical specification/
CQA plan requirements. Non-destructive
test results indicated all seams passed
test requirements. DAW reports for Site
1 indicated that seaming speed and temperature
remained stable, constant and
were within specified tolerances. DAW
reports indicated that seaming pressure
fluctuated above and below specified
tolerances. Interestingly, for Site 2, the
pressure and temperature were constant,
while the installer needed the ability to
vary the speed to avoid burnouts on the
thinner 40 mil (1 mm) geomembrane.
During trial welding, personnel
observed that the welding machine
" set " pressure, before the machine was
clamped onto the geomembrane, was
higher than the " welding " pressure displayed
after the machine was clamped
onto the geomembrane. The welding
pressure was approximately 70 poundsforce/foot
(311 (kN/m)) less than the
" set " pressure. Therefore, the seaming
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Geosynthetics October/November 2022

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