Dam Rehabilitation Using Geosynthetic Clay Liners

There are important design and installation considerations for geosynthetic clay liners (GCLs) usage in dam rehabilitation as illustrated by a recent case study. A Colorado earthen dam built in the 1930s had developed significant seepage. The reservoir was a needed water source for the nearby community. Various remedial options were considered for the project. Compacted clay had two distinct disadvantages. The remote location of the dam made hauling clay costly. Also, the high elevation made for a short season for constructing with clay. A membrane-backed reinforced bentonitic liner was chosen for rehabilitating the dam. Only three truckloads of the liner were needed to cover greater than one acre of dam face. Also, construction could be completed in a short time span before winter weather hit the site. Shear testing was performed by an independent laboratory to demonstrate slope stability of the liner and cover soil. Installation of the geosynthetic clay liner (GCL) followed guidelines similar to those used in landfill applications. The self-sealing property of the bentonite component of the GCL allowed for installation by overlapping the panels without welding the membrane seams. A review of seepage data for the dam prior to and after the GCL installation indicated that seepage had been reduced to an acceptable rate. 4 pp., 4 figures, 4 references.