By Steve Roades
Chlorosulfonated polyethylene (CSPE) geomembranes have a history of providing long-term performance in exposed environments. These geosynthetic barriers are increasingly referred to generically as CSM, but many people still refer to them by the no-longer-produced Hypalon elastomer brand name.
DuPont, which had manufactured the Hypalon elastomer formerly used in the lion’s share of CSPE geomembrane production, chose to exit the market in 2009–2010. That departure put a strain on the supply of this elastomer across many industries.
Japan-based Tosoh became a critical supplier for this essential component that has defined the longevity and success of CSPE/CSM geomembranes in reservoir design, floating covers, aquaculture, mine tailings containment, and many other applications.
In fact, the Upper Chiquita Reservoir design originally specified CSPE for both liner and cover. But with the project breaking ground in 2009, just at the onset of the supply crunch for CSPE, the project team opted to focus on the cover’s longevity as a protection and life extension aid for the liner.
Hence, polypropylene became the polymer for the geomembrane liner while the large cover was fabricated from CSPE geomembrane.