Patch Extrusion Welding of an Evaporation Pond As a Geomembrane Failure Mechanism—A Case History

This case history discusses the geosynthetic construction, use, failure, and repair of the 1995 Evaporation Pond at the EnergySolutions Clive Facility. A high priority is placed upon management of water that has contacted waste and that is stored in the Pond. A geosynthetic investigation into the root cause of repeated excessive leaking in the Pond is discussed. Two failure mechanisms were discovered and are discussed: damage due to maintenance activity and poor patch extrusion welding technique. The poor patch extrusion welding consisted of a large number of sharp, upwardly turned hardened extrudate that appeared to have worn against an overlying HDPE liner and created raised bumps and tears in the overlying liner. It appears that the combination of this unsatisfactory geosynthetic lining welding technique coupled with Pond operation and maintenance created a preventable geomembrane failure mechanism. Successful subsequent repairs of the 1995 Evaporation Pond are discussed.