3.4
GEOMEMBRANE SEAMING
A.
Seaming equipment shall be equipped with temperature gauges and readout
devices that enable continuous monitoring of equipment temperatures during
seaming. Electric generators shall be capable of providing constant voltage
under load and shall be underlain with a splash pad to collect spilled fuel or oil
when located on the GGcomembrane.
Surfaces to be seamed shall be overlapped a minimum of 4 inches and cleaned
of moisture, grease, dust, dirt, debris, and any other foreign material. No solvent
or adhesive shall be used for seaming without approval from the manufacturer
and the ENGINEER.
Where moisture or dirt interferes with the seam, a protective sheet of plastic
shall be placed below the seam overlap to protect the panels being seamed. This
may consist of a “rub sheet” of plastic that is pulled along beneath the seaming
apparatus.
Surfaces to be seamed using extrusion welding shall be cleaned of oxidation by
disc grinder not more than one hour before extruding the seam. Abrasion of the
seam area with the disc grinder shall not extend beyond the extrusion bead area
unless inspected and approved by the CQA Consultant. Tack welding of the
panels to be seamed shall not damage the Gcomembrane or adversely affect the
seaming operation. The top Gcomembrane of the seam overlap shall be beveled
and the extrusion apparatus shall be purged of heat-degraded extrudite before
seaming.
Should wrinkles occur, a cut shall be made along the ridge of the wrinkle and
laid flat so the edges of the material overlap. The overlap shall be extrusion-
seamed and any portion of the seam with less than 3 inches of overlap shall be
patched with a circular or oval patch extending a minimum of 6 inches beyond
the cut in all directions.
All T-seams and air testing needle holes are to be capped with a circular or oval
patch extending a minimum of 6 inches beyond the spot weld in all directions.
The Installation Contractor shall visually inspect seams and panels for holes,
crimps, abrasions, or defects, and shall mark each suspect location. Each
marked location shall be repaired, and non-destructively tested.
Methods of repair shall consist of spot welding small tears or over-abraded
areas where thickness of the GGomembrane was reduced by more than 6 mils
(0.006 inches) abrading and re-welding small sections of defective extrusion
welds and removing a defective seam and replacing with a new strip of material.
The surface of the GGomembrane in the seam/repair area shall be abraded no
more than one hour before the repair is made. All GGomembrane surfaces shall
be cleaned and dried at the time of the repair. Patches over larger holes and
File No. 3066.21 Geomembrane 02550 - 7 of 10 January 2021
