Definitions & Glossary 

CCTV - Closed-circuit television utilises video cameras and a limited transmitter to display images on a monitor or set of monitors. Commonly used for surveillance and security both in private buildings and public areas, this system can also be used to great advantage in observing and surveying areas where only cameras can go. I Spy uses CCTV to view small spaces and pipes, offering you recorded footage and our experienced evaluation of the state of your drains and chimneys. 
Sonar Tracing - Detecting that a fault is present is only the first step, and sonar tracing is employed to ascertain the exact location of the problem. A device that transmits a signal up through the ground is inserted into the drain or enclosed space and the signal is received above ground, to pinpoint the exact area with the fault. When used in conjunction with our CCTV cameras sonar can be a valuable tool for finding crucial parts of hard-to-get-to equipment. 
Sonar tracing can be successfully used through grass, concrete, and a range of other materials. 
Bore Hole - The name given to any narrow shaft drilled through the ground, in any direction. They are used for a variety of things including drainage, wells, gas pipes or liquid extraction, as well as exploration and site assessment. Regular maintenance is important for such pipes, especially those delivering water or materials that need to be relatively unpolluted. CCTV surveying allows for assessment of bore hole interiors, to catch faults before they cause a problem. 
Cavity Wall - A design comprising two outer skins and a pocket of space in between. Mainly the outer walls are masonry, which draws water out and uses the cavity as a drain for the water and a form of insulation for the building. In areas where there is heavy rainful and cold temperatures, cavity walls filled with insulation are used to great advantage. For inspection, holes are often left in the wall skins in order to facilitate CCTV cameras and surveys.