Peel Ports says there will be no more sinkholes at the new Liverpool 2 container terminal ?and says £4m repairs on the hole that opened up earlier this year will be finished by August.
The £400m Liverpool2 terminal, known for its giant red cranes on the Mersey, opened in November and can accommodate the world鈥檚 biggest container ships.
But in February, the ECHO reported that a giant cavity had opened up at the waterfront.
Now Peel Ports chief executive Mark Whitworth has today told the ECHO that detailed surveys have proved that only one small area at the dockside was at risk of sinkholes and that repair work is now starting on that area.
The affected area has been sealed off but Mr Whitworth says port work has now been switched to another part of the terminal, meaning port operations are unaffected.
And he says that despite the disruption caused by the sinkhole, plans to grow the terminal and expand it further are still on track.
Mr Whitworth said Peel and builder BAM Nuttall had were aware there was a risk of potential problems at one particular point on the sea wall.
He said: 鈥淒id we hope to expect to see nothing behind it? Of course we did. Did the hole open up quicker than we anticipated? Probably.
鈥淏ut on balance that鈥檚 probably a good thing ?it鈥檚 not like a minor issue here. It was a very clear distinct issue in that area.
鈥淣ow we just get back to a very simple civil engineering project.?/p>
How it happened
Mr Whitworth said that when the terminal was being built, the piling technique used to build the sea wall was changed. He said Peel was aware that meant there was a potential risk of weakness at that small point on the quay wall ?so a rock outcrop was left in place well below the waterline in front of that bit of the wall.
He said: 鈥淎s we were building L2, in the very early stages, we hit some ground conditions issues. They were using one particular method of piling and that method was subsequently changed to something that proved to be considerably more successful. Where were went from one method to another there was a point of change, a change of emphasis,
鈥淭he connection between those methods potentially represented a ?not necessarily a risk, but an area that we would want more certainty on.
鈥淲e got to the stage on the construction project recently where we went back to that area to test and verify it and ultimately used a dredging method that exposed a what turned out to be a weakness in the wall at that point.?/p>
Knew there was a level of risk
Mr Whitworth said Peel and contractors BAM always intended to go back to that point and remove the rock, and that they were aware there could be an issue when repair work started.
He said: 鈥淎s we start to remove that (rock) that exposes an issue at this point and the hole starts to emerge.
鈥淚s it ideal? Absolutely no it鈥檚 not. but it鈥檚 important to stress that we left the rock there because we saw a level of risk. We removed the rock and the issue came to light.?/p>
Clean bill of health
The Peel boss, named Business Person of the Year at last year鈥檚 ECHO Regional Business Awards, said surveys had now shown no other parts of the quay were at risk.
He said: 鈥淲e鈥檝e gone along and done various surveys all along the quay wall. They include things like a desktop study of the works that have been done. Everywhere along that quay wall, there was a clean bill of health ?the only area of risk involved, assessed independently, would have been there (where the hole emerged).
鈥淲e鈥檝e then gone along the quay wall with ground-penetrating radar which goes down 2m. Did anything come out? Nothing.
鈥淲e鈥檝e also all the way along the quay wall on the waterside and sent diving teams down to physically check if there鈥檚 any issues. And again, the only area we identified an issue was there.?/p>
What happens now?
The repairs will see what is effectively a second watertight barrier put into the ground behind the affected area.
Piles will be put into the ground and 鈥済rout鈥?will be injected between them to form the watertight seal.
Once that work is complete the sinkhole-affected ground between the new barrier and the sea wall can be dug out and then filled back in with aggregates. The sea wall will also be repaired.
Mr Whitworth estimated the repairs ?which will be paid for by builders BAM rather than Peel ?will cost between £3m and £4m.
Why do the repairs take so long?
Working on a tidal estuary like the Mersey poses challenges for builders.
Mr Whitworth said; 鈥淭he reason it takes long to rectify is that inevitably one of the biggest issues we鈥檝e got is the tidal range.
鈥淲hen you鈥檝e got a tidal range of 10m you can鈥檛 work in that area when the tide is up. You鈥檝e got to wait for it to go down.
鈥淭hat dramatically limits the time available to work in that area.?/p>
What impact has it had on Liverpool 2?
Liverpool 2 had its grand opening in November, but some ECHO readers have been intrigued at how quiet it has been since.
Mr Whitworth says they shouldn鈥檛 worry ?Peel Ports鈥?plan was always for the terminal to grow gradually, rather than having ships arriving from day one.
The five giant red ship-to-shore cranes that can be seen for miles, as well as the smaller cranes behind, are only the first phase of Liverpool 2. Peel plans to install three more giant cranes as business grows.
Originally, the northern part of Liverpool 2 would have been the first bit to open. But because of the sinkhole problems and repair work, the cranes have instead moved to the southern quay.
Mr Whitworth said: 鈥淚t (the sinkhole) has had a very small impact on the business in the short term. We lost a couple of weeks when we had to quarantine that area and make sure all was what we expected it to be but in terms of the ramp-up and the next phase of development, we鈥檙e going ahead as planned.?/p>
Mr Whitworth said negotiations with shipping lines are going well and he is confident that new services will soon be introduced from Liverpool 2.