The problem of characterising both active and closed landfills and waste sites is an increasing one in the light of increasing environmental legislation and poor historical records. A TerraDat geophysical survey can be rapidly carried out for a fraction of the cost of obtaining low-resolution information through invasive means, without disturbing the ground.
- Mapping leachate level within landfills
- Locating landfill boundaries
- Characterising variations in waste composition
- Mapping “dry” and “wet” zones for leachate control
- Investigating cap integrity
- Geological characterisation for new cell design
- Leachate plume mapping
- Locating voids or poorly compacted zones
- Landfill HDPE Liner testing
- Locating underground springs
The plan shows the how conductivity mapping can be used to rapidly locate the boundaries of a closed landfill where records are missing.
The section below is from a resistivity tomography survey and shows variations within a landfill cell including wet and dry waste, the landfill base and bedrock characteristics. Up to 1.5km of line can be acquired in one day.
Characterising the internal composition of a landfill is an important factor when considering the contamination potential and future of either an active or abandoned site. With non-existent or incomplete records, placing random boreholes and probes can be costly and ineffective. Knowledge about lateral changes in the properties of a landfill can identify features such as tip boundaries, different phases of tipping, saturated and dry ground, leachate plumes, and areas of groundwater ingress.
The purple lineations represent conductivity highs in trenches that were excavated into the underlying clay and filled with industrial waste. Subsequent groundwater ingress caused leachate accumulations that concentrated in the trenches.
Further processing of the EM data showed the leachate plumes to be migrating towards the site boundary thus providing optimal locations for pumping wells.