Brief descriptions of our capabilities in the areas listed above are provided in the following paragraphs. More detailed discussions of individual topics can be accessed by clicking on the links provided.
D’Appolonia has successfully applied geophysical techniques to many types of archaeological explorations. Some examples include:
- Location of burial plots
- Location of buried foundations and other cultural features
- Location of artifacts, including metal objects
- Identification of former paths and roads
Geophysical techniques that are commonly applied for archaeological explorations include DC resistivity, ground penetrating radar, magnetics and electromagnetics.
Geophysical methods have many applications as part of environmental site characterization studies, including:
- Identifying and delineating contaminant plumes in ground water
- Delineating the extent of free-phase and aqueous phase product at a site
- Mapping the location of utilities and underground storage tanks (USTs)
- Mapping the extent of buried waste in landfills and at uncontrolled dump sites
- Development of geological/geotechnical models to assess the distribution of subsurface contaminants
Typically geophysical methods such as DC resistivity, ground penetrating radar, magnetics and electromagnetics are used on environmental projects. Insights gained in the application of geophysical methods to environmental studies are documented in our publication titled, “Pitfalls of Geophysics in Characterizing Underground Hazardous Waste.” This publication has been used by the USEPA for some of their training courses.
Geophysical techniques can be used to supplement traditional site boring data and in many situations prove to be a very cost-effective means of defining subsurface conditions over a broad area. Typical applications include continuous definition of major stratigraphic interfaces, location of aquifer surfaces, determination of the elastic properties of soil and rock, and characterization of highly discontinuous subsurface conditions (sinkholes and voids) associated with difficult subsurface conditions such as karst terrain. D’Appolonia frequently employs geophysical methods for targeting more costly subsurface borings and monitoring wells. Techniques typically employed for geotechnical exploration include: borehole logging, cross-hole surveys, seismic refraction and reflection and DC resistivity.
D’Appolonia is a leader in the application of geophysical methods (DC resistivity and seismic reflection) for delineation of underground coal mine workings. For shallow workings (50 to 100 feet in depth), the most promising technique is DC resistivity, because this method can be quickly performed and is relatively inexpensive. For deeper targets (depths greater than 100 feet), the high resolution seismic reflection technique can be effective, especially when the S-waves are recorded. The utility of geophysical methods is that continuous data are generated that can be used to target geotechnical borings. D’Appolonia is currently performing a study for the Mine Safety and Health Administration (MSHA) to demonstrate the effectiveness of DC resistivity as the primary technique and TDEM as a secondary technique for detection of abandoned mine workings.
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