At a large copper mine in the U.S., a lined stormwater reservoir needed to be constructed for containment of runoff and process water. The integrity of the reservoir liner was critical as failure could result in contamination of groundwater. Solmax installed a double liner system, using Leak Location Conductive liner. This would ensure reliable electric liner integrity testing could be performed on 100 percent of the installed area to identify any installation damage.
The system comprised a 60-mil (1.5-mm) secondary liner of Leak Location Conductive geomembrane, a high-density polyethylene (HDPE) drainage net, and a primary layer of Leak Location Conductive White. Each layer consisted of 885,000 square feet (82,217 m2), totaling 1.7 million square feet (164,000 m2) of liner.
Solmax Leak Location Conductive liner is manufactured using a co-extrusion process. It incorporates a top layer, a middle base layer, and an electrically conductive underside layer comprising high-purity carbon black stabilized polyethylene, which allows the geomembrane to be spark tested after installation for defects with 100% reliability. For this project, the primary liner incorporated a coextruded upper white surface that reflects heat, ensuring a more stable liner temperature. It also improved visual detection of surface scoring and other impact damage, as the black underside of the lining shows up clearly through the white top layer when defects occur.
Spark testing was conducted by charged Neoprene pad that induces a charge to the conductive underside of the liner and to a six-foot (1.8-m) wide brass brush, creating an electrical circuit. The brush was then run across the surface of the liner. Where defects occurred, a visible spark and audible alarm sounded. To repair the defects, an extrusion weld bead or oval-shaped patch was applied. The spark testing was considered a success.
This article first appeared on the Solmax website, www.solmax.com/en/technical-library/case-studies.