7 Site Condition Considerations For Geophysical Services
Before you sign a contract with a geophyscial service provider, there are some general considerations for the site conditions you need to discuss with them for cost-effective and successful geophysical surveys.
Is the site generally accessible through vehicles or ATVs? Geophysical equipment for some tasks could be heavy and vehicle access could speed up the data acquisition process significantly. Sometimes the data acquisition design/logistics could be totally different depending on the easiness of vehicle access.
Is the site generally walkable? Is it heavily vegetated? Dense vegetation can require additional costs and/or permissions to clear survey areas.
What’s the ground surface material? Asphalt and concrete pavement can require additional work for electrical methods. Reinforced concrete could interfere with electromagnetic and electrical method. Concrete could also interfere with seismic refraction method.
Is the ground surface smooth, rough and/or with significant topography? Although most common geophysical techniques can now deal with difficult terrains, a flat and smooth ground surface is generally required for ground penetrating radar surveys.
Presence of highly electrical conductive surface materials such as newly constructed concrete or clay soils can significantly attenuate signals from ground penetrating radar resulting in shallow penetration depth.
Presence of aboveground and subsurface infrastructure, especially those containing metallic components can interfere with valid data acquisition and interpretation. For example, grounded electrical systems, metallic fences or underground utilities can prevent acquisition of valid electrical resistivity measurements.
Any other noise sources nearby? For example, a power plant can generate significant noises for electromagnetic surveys. Also, roadways and railroads can generate significant noises for seismic surveys.
Also, photos of the site could be very helpful. Some potential problems can be immediately identified from them by experienced geophysicists. Finally, a site visit by the service provider might be needed depending on the complexity of site conditions and the nature of geophysical services.