Svitzer Surveys uses many types of surveys to provide solutions for your project
Svitzer Surveys uses both geophysical and geotechnical data to research geohazards. Geophysical surveys are good at providing subsurface data at depths from 2m to 20Km and over large areas in either 2-D profiles or 3-D areal coverage. Methods used include reflection and refraction seismic, resistivity, surface wave analysis, gravity or magnetics.
Airgun seismic used as source for marine MASW offshore Canada
Monitoring techniques include visual and infra-red imagery, Lidar and other wavelengths of radar and various elevation measuring methods. All of these remote sensing techniques provide subsurface data however they cannot replace in-situ subsurface tests. This is where geotechnical techniques such as SPT, cone penetrometer and borehole coring provide confirmation of remoting sensing and engineering quality measurement. Generally geotechnical measurements extend to 100m or more below the surface, however depending on application or situation boreholes and soundings can extend hundreds of meters into the subsurface.
Geohazard risks can affect facilities such as pipeline or platforms, refineries or power plants and mitigating risk can range from simple surveillance to shutting facilities which are unacceptable risks; a good example of this is Japan’s Fukushima-Daichi nuclear plant. Japanese engineers are masters at designing for earthquake-induced ground movement, however the tsunami risks of the plant were overlooked and allowed a serious outage to safety systems. Risk mitigation at plants such as PG&E’s Diablo Canyon nuclear unit and Duke’s Dan River Steam Plant have been judged a sufficient risk to require shutdown.
Surface wave data(MASW) from Oklahoma windfarm mast site
The surface wave data acquired using geophysical techniques need confirmation and penetrating apparent anomalies is a proven technique. Geotechnical data, which includes boreholes and cone testing, are valuable methods for “ground-truthing” other surveys.
Boreholes are used where possible to test competent formation retrieving cores for further testing and the standard penetrometer, which measures even the hardest rock by resistance to hammer blows. Cone systems have strain gauges in their tips and are pushed into soils or sediments, which may contain pore water or pore fluid. Cone penetrometer systems can be mounted in specialist trucks, which makes the deployment of CPT testing fast and inexpensive in comparison to borehole drill rigs. Detailed data are available in real-time during testing, permitting on-the-fly mapping of stratigraphy and other subsurface features. CPT is a useful tool in geologic-hazard, hydrologic and environmental studies. This rapid and cost-effective approach is particularly advantageous in urban environments because no drill spoils are produced.
Cones are pushed from trucks or from within borehole drillstrings to test soils
Other data available from cone systems include temperature, pore pressure and dissipation testing which is a specialist measure of internal formation pressure.