Ground penetrating radar characterization of a landfill
Ground penetrating radar was investigated in an active landfill to determine if the in-situ water content could be measured. Water content is an important parameter in predicting the generation of landfill gas (LFG), an important renewable energy source. Unfortunately, predicting the quantity of LFG is difficult due to the heterogeneities present in a landfill and the lack of in-situ input parameters. GPR is a non-invasive, near-surface geophysical technique that provides high resolution images of dielectric properties in the earth's subsurface. A transmitter emits high frequency (10 - 1000 MHz) electromagnetic pulses through the subsurface, with the receiver recording the echo. Specialized software is then used to create images of the subsurface. The challenge with using GPR in landfills is the heterogeneity of the subsurface and the clay cap linear covering landfills, both affecting the transmission of the electromagnetic pulses. The use of GPR in a landfill was evaluated at the Region of Waterloo's Waste Management Centre. Measurements were completed using both the surface and the borehole approach. The results indicated that a borehole GPR can be used, with successful measurement of water content a function of borehole separation distance and frequency of the electromagnetic pulses. The developed approach was confirmed at the City of Hamilton's Glanbrook Landfill. The successful comparison of in-situ water content values to laboratory determined values at both landfills shows that GPR can be used to measure in-situ water content.