Lessons from the storm

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	February 2010 Lessons from the storm

When heavy rainfall on the Isle of Man threatened to cause a pollution incident along the River Laxey, the value of CIPP lining technology was proved once again.

CIPP lining manufacturers and companies have, almost since the technology was invented, laid claim to just how strong their liner materials are once installed. To some clients this has been seen as just "marketing". Well, not any more.

Some seven years ago, Insituform Technologies (ITL) undertook a pipeline rehabilitation project on the Isle of Man (IoM) using a 4.5mm thick standard, needle felt, resin impregnated CIPP liner to rehabilitate a deteriorated 225mm diameter, clay, foul sewage pipe, part of which ran under the river bed close to the village of Laxey, located on the east coast of the island.

Until recently, the pipeline operated as expected, passing flows out to sea off the harbour.

A major storm system passing over the Isle of Man produced major rainfall that caused the River Laxey to flow extremely fast.

These flows were sufficient to scour the riverbed to the point where the clay pipe and its concrete surround were exposed to the torrent at the point where it crossed the river. Cobbles and boulders brought down the river by the torrent crashed into the exposed pipe and its concrete surround, smashing it completely.

This was where the ITL Insituform CIPP liner came into its own. Whilst the original concrete casing and the clay pipe were completely destroyed where it was exposed to the worst of the river flow, the standard Insituform CIPP liner held fast without noticeable damage.

Pollution
Not only did the strength of the seven-year old liner allow the pipeline to continue operating despite the terrible conditions, the fact that it did prevented a major pollution problem in the river. If the pipe had failed completely, foul water flows would have spilled directly into the river water.

The polluting flows would most likely have continued for sometime as the pipe break would not have been detected until the river flows had subsided sufficiently to expose the breach.

Steve Knowles, of the Department of Transport for the IoM, says: "Had this clay pipe not been lined, we would have suffered a major pollution event during the flows caused by the storm.

"To repair the pipeline, since we had no need to install over pumping we saved significant time and effort in the works to bring the pipeline back to a fit-for-purpose state of repair.

"The continuing presence of the liner also now reassures us that we have that little extra level of security on the pipeline at the river crossing point should anything similar happen in the future."

www.insituform.co.uk

This article first appeared in Water & Effluent Treatment News February 2010 page 17

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