During the early eighties and speaking generally, the one internal pipeline inspection was either completed by the sewer inspection companies, who’d be inspecting mainly dry sewer pipe sections over short distances; typically not exceeding 150m and who stop if the pipe became surcharged to the point where the digital camera would become submerged and also the oil industry support companies who does run ‘intelligent pigs’ although the oil pipes to guage weld integrity, pipe wall thickness and overuse injury in order to assess pipeline longevity and safe operating pressure.
At this time the lake companies have been largely oblivious on the internal condition of these pipelines, adits, aqueducts and tunnels were starting out have concerns about the integrity with their assets, many of which have been constructed during the Victorian times or even more recently in early fifties together never been inspected and were unsuccessfully searching for companies and/or equipment that could accomplish such surveys.
Sometimes these folks were in a position to de-water the pipelines of course, if big enough diameter, they would send a confined space team into do a visual survey; such surveys were obviously fraught with potential dangers, including of which included the danger of collapse, flooding and also the accumulation of toxic gasses.
De-watering had its pair of potential risks for the structural integrity with the concrete, tunnelled and brick constructed pipelines; in many instances, small leaks created by displaced joints, erosion and localised damage etc. enabled the leaking water to find a path over the ground and over many years, earth will be passed from around the pipe, often producing large water filled voids forming round the outside of the pipeline.
The newly de-watered pipeline which may be partially reliant on the pinnacle water inside pipeline (attempting to push the walls out), to keep its structural integrity, could suddenly go through several a great deal of water outside the pipeline (attempting to push the walls in), creating localised aspects of external questionable, which could often lead to pipe failure and localised collapse, causing subsidence of the ground across the pipeline manifesting as holes on your lawn that will appear ‘over-night’.
At about now there was an increasing demand from your Water Companies to send divers up water filled pipes equipped with CCTV cameras, to survey as far for their nerve or umbilical length would permit.
In a very short time the HSE Diving Executive, showed an fascination with the protection aspect of sticking divers up pipes and before long an excursion selection of around 30m as being a maximum was considered safe, providing that every the necessary safety precautions were in place.
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