Geosynthetics October/November 2022 - 20

Evaluating new technologies to limit geomembrane destructive testing
Consistent
with ordinary
geomembrane
installation, the
geosynthetic installers
established the target
seaming temperature,
speed and pressure
appropriate for
the geomembrane
material and ambient
weather conditions.
holes and, if a deficiency is found, there
is no data to indicate its extent. At best, a
destructive sample/test passes and confirms
that it was not needed in the first
place. At worst, a seam is subjected to
several additional destructive samples/
tests to try to identify the extent of the
seam failure.
Pilot project and field study
evaluation background
Sequoia Services was retained by the
owner as the general contractor for two
projects that included geomembrane
seaming. Wood Environment & Infrastructure
Solutions, the design engineer
and Construction Quality Assurance
(CQA) firm for both projects, collaborated
with the owner to determine how
to implement new technologies to limit
destructive testing for future, larger-scale
projects. The team met with regulators,
material manufacturers and installers
to understand how to achieve this goal.
The team recognized that monitoring
and evaluating geomembrane seaming
parameters using data acquisition
Project ID
Project type
Project size
Lining system profile
(top down)
Geomembrane installer
Data acquisition welder
Installation date
TABLE 1
Welding parameter
Target temperature
Target speed
Target pressure
TABLE 2
20
Geosynthetics | October November 2022
Site 1
± 40°F (4.4°C)
± 0.5 feet/minute (0.15 m/minute)
± 20 pounds force (89 N)
Site 2
± 40°F (4.4°C)
± 0.5 feet/minute (0.15 m/minute)
± 50 pounds force (222 N)
Site 1
Leachate pond replacement
0.20 acre (.08 hectare)
60 mil HDPE primary
geonet composite
60 mil HDPE secondary
GCL
Chesapeake Containment
Systems Inc. (CCS)
Leister Geostar G7
December 2020
Site 2
Temporary processing pad
20 acres (8.09 hectares)
Geonet composite
40 mil HDPE
Environmental Specialties
International Inc. (ESI)
Demtech VM-20/A with Pro Data
March 2022
welding machines would enable pinpointing
seam defects. Furthermore,
seam contamination could be reduced
thereby improving seam quality by using
taped geomembrane edges. The resulting
goal was to evaluate these new technologies
in practice aiming for destructive
testing only as the data indicated a need.
Two pilot projects and field studies
were conducted. The project-specific
details are summarized in Table 1.
Project design
and specifications
Data and quality-based
geomembrane-seaming
Wood designed the projects, preparing
construction drawings, technical specifications
and the CQA plan. Technical
specifications for the high-density
polyethylene (HDPE) geomembranes
included some key differences from a
standard geomembrane specification,
including requiring taped geomembrane
edges to limit seam contamination and
requiring the use of data acquisition
welding (DAW) machines to continuously
monitor double-track fusion seaming
performance.
The technical specifications required
fusion welding machines equipped with
data acquisition capabilities to measure,
record and display seaming temperature,
speed and pressure as well as to display
voltage. The technical specifications
defined the required tolerances for each
seaming parameter presented in Table 2.
Consistent with ordinary geomembrane
installation, the geosynthetic
installers established the target seaming
temperature, speed and pressure appropriate
for the geomembrane material and
ambient weather conditions.
The technical specifications and CQA
plan defined procedures for data/qualitybased
field seam evaluation instead of
prescribing destructive seam sampling
Geosynthetics October/November 2022

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