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Underwater PVC Lining Coachella Canal

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					Underwater PVC Lining
Coachella Canal
          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.
canal.
          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