project summary
Layfield supplied and installed the material for this liner replacement. The Idaho National Laboratory required a warm waste pond liner replacement that would take place in two phases over the course of a year. The replacement would require the construction of a Sand Bag Berm, double liners of 45 Mil HypaFlex™ CSPE, and Nonwoven Geotextile and Geocomposite layers.
challenge
Liner removal and a typical anchor trench were not an option due to radioactive contamination within and around the perimeters of the two waste ponds. The engineered detail was to leave the existing double liner system in place and build an elevated berm on the existing ground elevation in order not to disturb the potential radioactive contamination under the ground surface.
solution
The current slope elevation and the new sandbag berm would make for a difficult transition. During construction, the east pond could be required to store liquid from the reactor above the original design elevation. As a worst-case scenario, the pond needed to be watertight between the existing berm and the new sandbag berm. Radiation II training was also a requirement for all personnel inside the posted areas.
result
The sandbag berm was built to maintain the existing slope angle to minimize the possibility of bridging. On waste Pond #2, a prefabricated skirt was seamed to the current HypaFlex™ CSPE liner with over 20 years of use extended up and over the sandbag berm. A watertight barrier was formed between the existing top of the berm and the top of the new sandbag berm allowing the water from Waste Pond #1 to be pumped into Waste Pond #2, enabling the installation of the double-lined system.
