Video inspections in wells can detect the construction characteristics of the well: the blind and filter pipes, the respective installation depths and any variations in diameter in the hole. The television probe – which must be waterproof and resistant to the pressure generated by the water column above it – is equipped with a special wide angle lens that allows detailed diagnosis of the coating. Any anomaly may not only be highlighted at a certain depth from ground level but may also be photographed or even filmed during the investigation. Performing a video inspection can determine the causes of the most common problems that can affect a well in the course of its productive life, such as the presence of sand and a decrease in water flow. Furthermore, it can detect abnormalities such as deterioration, deformation, corrosion, cracks and excessive deposit on the bottom. The well TV camera can assess situations of risk from degradation and the appropriate measures needed to repair the well. Maintenance can therefore be conveniently scheduled according to the typical characteristics of the groundwater and resulting problems. It will also be possible to rapidly complete the missing documentation for existing wells (total depth, depth of installation of the filtering features, type of pipes and efficiency) and to check the actual conditions before performing costly repair work.
In the case of applications in boreholes or other kinds of holes, characterised by horizontal rather than vertical development, it is necessary to use borehole TV cameras with even more compact dimensions, especially those equipped with a “push-rod” system: this is a special fibreglass cable wound around a special roller reel which – mounted on the head of the TV camera via an adapter – provides a thrust to the camera which allows it to move progressively into the hole.
If visual inspections are carried out in small holes in buildings and constructions in general, the smaller size becomes indispensable. It is then important to use miniature instruments called endoscopes, characterised by a head with a diameter of just a few millimetres and fibre optic cables for transmitting the image that are no more than a few metres long.