Mon. May 16th, 2022

Isle of Wight Observer News

The Island's Free Newspaper

Massive engineering feat sorts out Appley sinkhole

2 min read

At last, after 15 long months and a total cost of £7million, the Appley sinkhole has been repaired and the newly tarmacked road is open to traffic.

The massive engineering project took more than 30,000 man-hours to complete and the engineers can look back at a job well done.

Site manager, Nick Walton of MGJV, on behalf of Southern Water, said: “It is hugely satisfying. We have safely and effectively repaired the collapse and people in Seaview and Ryde can safely use their toilets again!

“During the works, we managed to keep open access to the beach for pedestrians and Ryde Inshore Lifeboat and we adjusted our working hours to accommodate local businesses as best we could and have left the surrounding roads in a better condition than when we started.”

Looking back to January 2020, when the sinkhole was first reported, Nick said: “We could see straight away that the main sewer had collapsed; it was blocked full of debris, rocks and boulders weighing up to 900lb.

“It was clearly unsafe for us to repair it directly from the area where the original sinkhole appeared. As a result of this, we created a new shaft, adjacent to the beach, from where we carried out the repair. After our initial investigation, we determined that the solution was to reline the sewer via the new shaft and there were five main steps in this process.”

The processes started with accessing the extent of the damage via specialist video inspection software. Specialist tunnelling contractors then installed pipe jack to the outside of the sewer and removed the blockage and defective pipes, installing a steel pipe replacement.

The line was thoroughly cleaned and inspected via video, to ensure all debris was clear. Then bespoke liner, reinforced with special glass fibres and impregnated with resin, was made permanently resistant to corrosion.

The liner was winched through the damaged pipe and then inflated under air pressure to attach it to the inner walls of the damaged pipe. A UV light train was then passed through the lined pipe at a specified rate to cure the resin. Once fully cured, the lining now acts as a new pipeline.

Nick added: “The total collapse was approximately 12m (40ft) length of Ryde’s main 1,050mm sewer at depth of 10m below ground level; it was a huge feat of engineering and £1m of the total cost went towards future-proofing to make sure it doesn’t happen again.”

And after 15 months on the Island? Nick said: “It’s been a wonderful spot to work with it being by the beach and sea, but I’m now going back to the mainland for my next job!”