The XR-5 ethylene interpolymer alloy geomembrane was specified for the primary and secondary containment liners for a zinc and diversified metals production facility in Mooresboro, N.C., owned by Horsehead Holding Corp.
“XR-5 was chosen for its chemical resistance to sulfuric acid, kerosene and weak hydrochloric acid,” said Bert Olah, project manager for CSD Engineers in Pittsburgh. “A double liner system of XR-5 was used, as one can’t afford for the chemicals to compromise the environmental area.”
In phase 1, the XR-5 was utilized as a barrier liner below the concrete floors of the settler building installation, where solvent extraction occurs. This process is an acid leaching of zinc using acid raffinate and sulfuric acid, followed by solution neutralization.
The ease of installation of approximately 180,000 sq ft of the liner proved to be advantageous to the contractor and set the stage for phase 2, which consisted of open ponds. Seven ponds at the facility operate with a double XR-5 liner and geo-net system. The pond slopes below are continuously exposed to high concentrations of ultraviolet light from the sun.
In total, more than 500,000 sq ft of XR-5 were installed.