Characterize proposed waste disposal sites.
Many sites have been proposed for deep nuclear waste disposal around the world. To be suitable for long-term storage, a site must be free of fractures and permeable layers that could transport groundwater through the disposal site. A thorough geophysical characterization of the proposed site is essential.
AMT/MT is highly suitable for this task. The technique penetrates deeply, and easily detects conductive, water-filled faults and layers. A study by Atomic Energy of Canada Limited (AECL) in 1980 eliminated unsuitable sites proposed near the Chalk River Nuclear Laboratories and Whiteshell Nuclear Research Establishment.
Explore for CO2 sequestration sites.
The threat of global warming has put a focus on reducing carbon dioxide emissions; one proposed solution is to sequester the gas underground. Taiwan has already embarked on MT exploration
in the hopes of finding suitable sites.
Map saltwater intrusions.
The New Jersey Geological Survey used the Time Domain EM technique in 1985-87 to map shallow salt-water intrusion into fresh water aquifers in coastal zones. The intrusion has caused the abandonment of water-supply wells in Cape May City. AMT techniques could be used in areas with deeper intrusions.
In 1992 in the Santa Catarina basin in Mexico, the University of Mexico (UNAM) used MT/AMT to identify possible channels by which leakage from a landfill site may be contaminating the deeper aquifer (400 m subsurface) supplying water to 2 million people in the southern suburbs of Mexico city. They reported that "in order to prospect for the deep aquifer units (>200 m), the AMT/MT sounding is the best practical cost-effective technique available."
The Geological Survey of Finland used Spectral induced Polarization (SIP) in 1994 to characterize soils and fills contaminated with hydrocarbon products, concluding that "the phase spectra changes occurring in contaminated soil with increasing maturation time can be utilized as a diagnostic signal of contamination in long period monitoring."
In some cases, the techniques can detect contaminants directly because of their electrical characteristics. In other cases (e.g., tracking the movement of organic pollutants with little or no electrical expression), it is usually sufficient to determine the topography of the underlying bedrock. The contrast between conductive overburden and resistive bedrock is easily mapped with MT/AMT, at depths to several kilometres.
See the Groundwater Exploration
page for more environmental- and water-related applications.