Geosynthetics October/November 2022 - 22

Evaluating new technologies to limit geomembrane destructive testing
CCS seamed approximately 520 feet
(158 m) of double-track fusion seam on
the primary geomembrane and approximately
550 feet (168 m) on the secondary
geomembrane. In addition to the
machine display, the equipment allowed
CCS personnel to monitor seaming using
a tablet PC (connected to the welding
machine by Wi-Fi).
Due to site constraints, the preferred
FIGURE 4 Leister Geostar display
deployment direction did not always
allow the taped edges to shingle properly
toward the pond sump. Given the small
size of the project, some of the panels
were rotated by hand to allow the taped
edges to mate properly. Additional area
was prepared to be able to deploy the
geomembrane from the opposite side of
the pond and alleviate the need to rotate
the sheets.
Each welding machine automatically
assigned sequential seam numbers (e.g.,
1, 2, 3). Therefore, the first trial seam
began with seam number 1 and production
seams started with the next sequential
seam number after trial welding (e.g.,
3 or 4), depending on the number of trial
seams prepared. At select times during
the day, the geosynthetic installer transmitted
DAW reports electronically to
CQA personnel in portable document
format (.pdf). DAW reports were comprised
of the following information:
1. Seam summary record: One-page
report showing four seams (per summary
record), including 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.
2. Graphical report: One page showing
the temperature, speed and pressure
plotted versus the data measurement
position (distance) and color coded
to visually identify out-of-tolerance
seaming parameters.
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Geosynthetics | October November 2022
3. Detailed report: Multiple-page seam
record reporting each data measurement
position (distance), temperature,
speed, pressure, latitude and
longitude. Out-of-tolerance seaming
parameters were reported in red
text to visually distinguish them. The
minimum and maximum temperature,
speed and pressure, as well as the
specified welding limits (tolerances),
are summarized at the end of each
detailed report.
Site 2
Learning from the Site 1 installation,
which showed consistent speed and
temperature, but out of tolerance pressure
with acceptable results, the pressure
envelope was expanded from ± 20
pounds force (89 N) to ± 50 pounds force
(222 N) with the speed and temperatures
remaining the same. ESI used Demtech
VM-20/A (with Pro Data) double-track
fusion wedge welding machines to seam
the geomembrane. Unlike the Leister
machine that reported data recoding
intervals in inches (cm), the Demtech
equipment recorded data in time intervals.
ESI set the data recording frequency
to one recording every second.
ESI seamed approximately 35,601
feet (10,851 m) of double-track fusion
seam on the 40 mil (1 mm) HDPE geomembrane
over 10 workdays.
The processing pad was designed
to drain radially with a high point in
the center. This configuration did not
allow the taped edges to be used with the
desired panel shingle to allow down-slope
drainage to the perimeter channel. Due
to the fine particle size of subgrade soils
and the limitation on using the taped
edge on the major seams, CQA personnel
collected eight destructive samples to
confirm seam strength without the taped
edge. (See Figure 5.) The eight destructive
samples passed. In comparison, a
typical installation based on the current
Geosynthetics October/November 2022

Table of Contents for the Digital Edition of Geosynthetics October/November 2022
