Case History of a 25-Year Old Exposed CSPE-R Geomembrane: Fid-Bau Portal

Case History of a 25-Year Old Exposed CSPE-R Geomembrane

Koerner, George R. / Rafter, Timothy

The opportunity presented itself to sample a 25-year old CSPE-R geomembrane. Sheet material was taken and tested so as to compare to the archived (original as-manufactured) material. The aged values were also compared to the current generic specification; GRI-GM28 for CSPE-R. The upper ply of the scrim reinforced geomembrane has degraded over its 25-year exposed lifetime. It is currently being replaced for that reason. That said, an assessment of the residual properties and, even further, to compare these properties to archived samples of the original material could not be ignored. Thus field performance is unequivocal. The prediction of 20-30 years exposed lifetime for a CSPE-R floating cover geomembrane is quite accurate in this regard. Even further, the original properties would pass a current specification of the material indicating that little has changed insofar as its formulation is concerned. The above said, the lack of a domestic supplier of CSPE-R is somewhat disconcerting since the material is written into many owners specifications and regulated in some jurisdictions. Two current strategies seem to be at play, (1) resin supply from other countries and (2) alternative resins like fPP-R, LLDPE-R and EPDM-R. Time will tell as to future directions for floating cover geomembranes.