Underwater PVC Lining
Problem: A nine-foot-deep canal, conducted in two steps. The dredge
built in 1942 in sandy desert soil now leaks prepared the canal while the paver placed
up to 115,000 acre-feet annually - enough the geomembrane (bonded with geotextile)
fresh water for up to 150,000 households. and immediately covered it with 3 inches of
The canal needed relining but the project specially formulated concrete. To install the
had to be accomplished without draining geomembrane liner underwater, a unique
the water. tracking system was designed that allowed
Solution: Develop equipment that the liner to be rolled out flat against the
trims and grades the canal and then lines it sides and bottom of the canal. EPI
in one multi -layered process with a developed and patented the proprietary
polyvinyl chloride (PVC) geomembrane, fabrication process to accommodate this
geotextile and a concrete cover. All tracking system.
accomplished while tons of water flow BuRec selected PVC as the appropriate
through the canal. liner for the project for four reasons:
A prototype project for lining 1.5
miles of the Coachella Canal in southern 1. Availability in large sheets. 60-by
California began in 1988. The project is to 200-foot panels were used to provide
present new technology and methods that the one million sq. ft. of liner.
can be used to line all leaking portions of
both the Coachella and All-American 2. Flexibility. PVC is flexible over a wide
Canals. This project marks the first time range of temperatures, permitting it
PVC (or any geomembrane) has been to conform to the subgrade better
used for underwater lining of an operating than other geomembranes.
The U.S. Bureau of Reclamation 3. Easy field welding. PVC is easily
awarded the Kiewit Pacific Company of field-welded with a solvent. Its
Santa Fe Springs, Calif., the contract to tensile strength, puncture, abrasion
develop equipment to line the canal. Kiewit and tear resistance properties were
subcontracted with EPI to supply the important to minimize damage
custom -fabricated PVC liner and to provide during installation.
on-site hot wedge field welding of the
panels during installation. 4. Proven record. PVC has been used
Two gigantic machines were for four decades as a canal-lining
designed and built - a dredge and a paver - material in reclamation work.
so that the operation could be