The water pipes across the van Stadens River have always had a significant leak. These pipes exit the sand dunes pretty high up and do not lie in water.
During the recent drought it was not viable to scour and seal the leaking pipes as the amount of water that would have been lost in this operation would have been significant. Bear in mind that some estimates are that 40% of the water loss occurs from Dam to Meter – i.e. due to such leaks and faulty air valves in the pipeline which runs along the coastline and through private property via servitudes.
Property owners along the pipeline confirm that it has been almost 4 years since they last saw municipal teams keeping the grass cut and keeping trees and bush off of the servitude along the pipeline. As a result, we presume that visual inspections and maintenance of the pipeline and air valves were also then erratic. At this time we do not know how many air valves are along the pipeline but concerns have been raised around poor to nil maintenance of these vital components. Apparently the air valves rust and are unable to return to a normal resting state once they are activated to reduce the pressure, resulting in ever increasing water leaks.
According to a spokesperson (yes I heard this person talking!), a municipal team was scouring the pipe line on Wednesday, in preparation of fixing the leak that has been visible for years. One of the air valves either malfunctioned or blocked and continued to leak water causing the the soil under the pipe to erode and the pipelines to collapse. The leak was reported at about 6:00 pm on Wednesday evening to 0800 20 5050 but the metro did not react. On Thursday the hill had washed away.
As the source said; “The story of it being due to the heavy rain is a lot of crap. Bullshitting us again.”
The smaller 700mm pipeline should be fixed over the weekend. The larger 1000mm concrete pipeline requires some more time. Current estimates for the repair and rehabilitation run into a period of one month
Judging from the images that have been doing the rounds one would notice that the broken pipelines are not sitting in water, their valves look rusted and one has to ask the question; “Why would the pipelines break in an area where maintenance had been started?”
Compounding the concern is that the break is on private land and the van Stadens Resort is the subject of recommendations in the Kabuso Report.
Who said they wanted to live in interesting times?
Images below courtesy of Dave Hutton:
Lest you think that air in pipelines is well, just air, and of no consequence I recommend that you read all about the air in pipelines, what it can cause and how engineers try to reduce and control it using air valves. In the short time available to me I couldn’t find a definitive maintenance schedule but presume that many factors contribute to proper maintenance of the air valves.
From ARI South Africa:
The entry, control and release of air from pipelines is a major, though often, hidden problem in pipelines used for water supply, foul water drainage and effluent discharge. Considerable costs are incurred in providing air release valves and chambers, and in deepening pipe trenches so as to provide the minimum gradients that are thought necessary to enable air bubbles and pockets to move towards the valves. Air valves require regular maintenance, but in practice this is rarely undertaken and there are numerous instances of their leaking and/or failing to operate correctly. In certain cases, vibration of the valves during start-up or shut-down of pumps can cause air to be drawn into a pipeline – the exact opposite of what is intended. Where effluent and water transfer pipelines need to be laid under water in coastal or tidal areas, air valves cannot be used at all and the bed topography may result in very flat pipe gradients.
Download and read a fascinating report on Air in Pipelines by C.S. Lauchlan, M. Escarameia, R.W.P May, R. Burrows and C. Gahan.
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