Volume 29, Issue 1 (January 2006)
Geotechnical Sensor System to Monitor Injected Liquids in Landfills
A field-scale horizontal permeable blanket made up of crushed recycled glass was built in an active municipal solid waste (MSW) landfill to recirculate leachate. The permeable blanket is a new method for subsurface leachate recirculation or liquid injection. Leachate injection rates in the blanket ranged from 1.1–3.6 m3/h/m. An automated sensing system consisting of moisture content sensors, pressure transducers, and temperature sensors was designed to monitor the migration of injected leachate inside the blanket. The sensors were embedded in the blanket and connected to a data logging system. All sensors were able to detect the leachate migration within the blanket. The TDR and impedance moisture content sensors could not detect the migration of injected leachate once the surrounding medium got saturated. The pressure transducers and temperature sensors were able to detect leachate migration irrespective of the degree of saturation of the blanket. Unlike thermistor sensors, temperature readings measured by thermocouple sensors were influenced by air temperature.