Landfill Depth Profiling
Recently, we were asked to conduct a high resolution resistivity survey to determine depth to bottom of fill and landfill areas at a huge Brownfield project in Arizona. Profiles were conducted at areas of suspected debris landfills and areas of uncompacted fills to compliment proposed environmental and geotechnical drill sites. The native formation at the site was an electrically resistive conglomerate.
This profile was conducted as a baseline study, since historical records indicated that it had not been disturbed. As you can see, there is a fairly shallow layer of fill (1.5 meters) over the more resistive native.
This profile was conducted in an area of suspected buried trash. As you can see, large bull's-eye areas of high conductivity exist. These areas are interpreted to be metal and other conductive land fill debris and are up to depths of more than 16 meters.
This profile was conducted along a river bank in an area where a cut bank was reportedly filled, but not compacted. As it turned out, the fill was more conductive then the native soil and the cut bank is easy to recognize.
This profile was conducted in an area of suspected concrete and rock debris. As you can see, large Bull's-eye areas of higher resistivity exist. These areas are interpreted to be buried concrete and decorative boulders and extend to depths of up to 20 meters.
Some benefits to consider:
- This survey work was conducted despite ongoing operations at the several properties.
- These surveys can be conducted in endangered habitat sensitive areas.
- No permitting is required for conducting these surveys, and therefore, can be scheduled ahead of drilling.
- When conducted in conjunction with exploratory borings or test pits, it can increase the overall extent of subsurface information as well as aid in boring and test pit location.
Southwest Geophysics has used Resistivity Surveys to:
- Map Faults
- Map fracture zones for water well sighting
- Map large karst voids and sea caves
- Find depth to groundwater, in certain specific situations
- Generally characterize subsurface geology.
- Aid environmental contamination flow projects when used to evaluate locations of paleo stream channels or fault zones.
- Find buried bedrock valleys, which can be an important source of groundwater in unconfined aquifers.
- Vertical joints or cracks, which can indicate subsidence features.