Mammoth Cave in Kentucky is the longest known cave system in the world, drawing more than 2 million visitors each year.
In 1984, the National Park Service installed two wastewater stabilization ponds to treat domestic wastewater that flows from the Great Onyx Job Corps Center, a vocational training facility located on the grounds of Mammoth Cave National Park.
Operating in series, the primary treatment pond measures 190 by 200 ft and the polishing pond measures 300 by 200 ft. Once treated, the effluent from the ponds is released into the Nolin River, a tributary of the Green River, which also runs through the park. Both rivers are recreation destinations for Mammoth Cave visitors and outdoor enthusiasts.
Lining the treatment ponds to protect the surrounding grounds and waterways from the wastewater contaminants is XR-5 geomembrane. A proprietary woven polyester-base fabric is the foundation of its dimensional stability, tensile strength and puncture resistance. The geomembrane can undergo a second stage of manufacturing in a controlled factory environment, which yields single sheets as large as 15,000 sq ft. At Mammoth Cave, the largest pond was lined with XR-5 by using five panels and four major field seams.
After more than 20 years of exposure to chemical and organic waste contaminants, ultraviolet rays and extreme temperature swings, the original liners installed in 1984 still protect the park’s grounds and waterways today.