Geosynthetic Membrane Monitoring System (GMMS)
Geosynthetic membranes are used in landfill caps and liners. These relatively thin (e.g., 1.5 millimeter) layers of high-density plastic are designed to prevent rainwater infiltration through caps and prevent leachate migration through liners. After installation, site managers usually know little about the status of these membranes. Current practices usually involve drilling nearby wells to monitor sites.
Sandia National Laboratory (SNL) has developed a system to monitor the liners, called the Geosynthetic Membrane Monitoring System (GMMS). It consists of fiber optic lines and sensors embedded into the geosynthetic membrane material. Sensors can measure subsidence, moisture content, and fluid levels. They can also detect tears in the membrane, detect local subsidence where drums and waste boxes may have collapsed, determine hill slope stability, and monitor road and runway stability.
Limitations and Concerns
Leaks, tears, and other factors cannot be detected unless there is a sensor nearby. The effectiveness of this innovation thus relies on the density of the lines and sensors.
This technology is intended to address the need to monitor geomembranes in landfill covers and liners for the effects of water accumulation and subsidence, as well as membrane age. It provides important information on the integrity of the covers and liners; it is not contaminant specific.
Technology Development Status
This is a pilot project. Prototype monitoring systems have been installed in the laboratory. As of 1997, experiments were to be performed to scale up the system to the size of a landfill cover system. The use of geomembranes in geo-technical and environmental applications is widespread, and monitoring systems are generally lacking, so the potential for this technology is significant.
Other Resources and Demonstrations
As a demonstration of this technology, Sandia National Lab (SNL) has installed a prototype monitoring system in laboratory test frames, and the sensors measured the strain across the membrane. During 1997, it was scaled up using a test cell at Sandia.