Cross hole ERT and moisture change profiling

• Price: Price on application

We can make direct burial cables with electrodes spaced appropriately for lowering down especially drilled uncased holes then backfill the holes to contact the takeouts on the cable. Connected to telemetry, this is an excellent way to resolve moisture changes in bulk soil. Unlike with surface imaging, this technique does not need to lose resolution with increasing depth.

If two or more holes are drilled and electrodes are lowered down each hole then results are superior to single hole ERT where some electrodes are placed on the surface. We can augment such geophysics with Sentek capacitive moisture probes extending down the holes as well.

Cross hole or surface to hole ERT can be conducted at any scale. Hand augers can be used for topsoil 3D ERT but typically, for resolving moisture changes down to the water table, sugared drillholes are required. We can auger with our rig down to 12m deep provided we can manage cave-in of sediment. Once the auger reaches the water table it may be difficult to keep the hole open beneath the water table long enough to insert the electrodes (pushed in on outside of the end of a PVC piezometer tube). 

For deeper holes, cross hole ERT in unconsolidated alluvium may be practical only with use of more substantial drilling rigs, or if in sand by jetting with our rig.