Q&A: Andy Mitchell, chief executive, Tideway

At the end of the month, main construction on the Thames Tideway Tunnel begins. Why is the Tunnel needed? And will everything run smoothly? Utility Week speaks to Tideway chief executive Andy Mitchell to find out.

Q: Is the construction work due to start on schedule?

A: We’ve actually been at it for most of this year – the enabling works at Blackfriars have been going on all year.

When we talk about starting main works, we mean the big civil engineering works. The diaphragm walling, which is how the shaft will be started, will start at the end of October or early November.

Our four tunnelling machines are being designed at the moment. They take about a year from decision-to-go to deliver on-site, and we expect the first tunnel boring machine to arrive in May next year. The next two will then arrive later in the summer, and as soon as we’ve got down to the bottom of the shafts, we’ll be lowering the TBMs down them.

The first machine, which will be in the Fulham location of Carnwath Road, should start tunnelling by Autumn of next year. That is when we become really visible.

Q: Have you taken any learnings from previous large infrastructure projects?

A: Hell yes.

The precursors on the tunnelling are the Lee Tunnel and Crossrail, but also the National Grid tunnels which were going on at the same time. The tunnelling per year that we’ve got to do is somewhere between a third and a half of the tunnelling per year that was going on a couple of years ago.

The Thames Tideway Tunnel starts in Hammersmith at about 30 metres deep, and goes down to about 65 metres deep where it meets the Lee Tunnel. But the Lee Tunnel keeps going again, it is deeper than anything we have got to do.

Crossrail, being closer to the ground and under all sorts of listed buildings, had a lot more challenges in terms of proximity to neighbours, utilities, tube lines, gas pipes, water pipes.

They had a much harder job there than we’ve got because we’re under the river. There aren’t any manmade structures above us, which is something Crossrail would have loved, and we are not weaving in and out of all the tube systems in London. There are only two pipes that go lower than us and they are Thames Water assets, but very quickly we’re below anything else.

There truly has never been a better time to build the Tunnel, with everything that’s gone on in the past. We’ve got a lot of the experience in the team, and technically the job we’ve got to do isn’t as hard as our predecessors’.

Q: Critics claim the Tunnel is not needed, as there are cheaper alternatives available. What would you say to them?

A: If you then do the maths and work it through logically, the argument isn’t a valid one.

One of the reasons that our tunnel is a metre bigger in diameter than the Crossrail tunnels is because it has a volume of 1.6 million cubic metres. And the scale of blue-green response or capability that would be needed to replicate what the Tunnel will do is enormous.

Philosophically, are there other ways of addressing the issues that we have? Yes. Practically? No, and certainly not in the timescales.

The point at which this became a binary argument – you either do the Tunnel or you solve this with blue-green type measures – was a bad day, because it should never have been either/or, it should have been both.

London has got to understand how to get more water-sensible as we go forward – but that’s all about mitigating a future deterioration. There is just no way that, practically, there is anything that could be done on the blue-green line that would compete with the scale of what the Tunnel will achieve.

I wish it was different, but it isn’t.

Q: Do you have any concerns about funding for the Tunnel after Brexit?

A: No.

Our funding structure involves equity from our shareholders. We have a number of covenants and restrictions on how the financing works, and there is a requirement that at all times we respect the 70:30 borrowing to equity ratio.

Our shareholders decided to put £1.3 billion of their own money in first. Then, by the time the lenders’ money was being deployed, a significant number of the risks would have been addressed – which I think was a smart move.

The market has shown that we’re an attractive place to put money. The point that we make to shareholders or potential lenders is when we’ve finished [construction], what we end up owning is the dumbest asset that anyone could ever invest in – a series of shafts and tunnels built to last. And there isn’t a question mark over maintenance costs, because effectively there aren’t any.

We’ve spoken to many potential investors, all of whom see that this is worth putting money into. It’s a good investment and that is why we’ve borrowed as we have, and we don’t see that changing.

So no, I don’t have any concerns at all.

Q: Are you confident the project will be completed on time and on budget?

A: Definitely. There has never been a better time to do it.

The main contractors have submitted contract programmes that show an 18-month-earlier completion, but the stretch target is the whole two years. We’ve been pursuing that from the beginning. We mobilised on all of our sites early, and we’ve got clear views as to what we’ve got to do to achieve that earlier schedule.

Chasing an earlier programme, we find it very difficult to see how we’ll overrun on time and, therefore, how we’ll overrun on cost. We’ve got no intention of running over on either of those two.

We’re one year in, we’ve started early. We have found problems and we’ve had delays, but the good thing is we’ve found the delays earlier, and have dealt with a number of delays that were potentially there, but we’ve dealt with them before we would even have started on the original schedule.

We’re confident in our schedule, we’re confident in our ability to achieve that at least the 18 months early, we’re still confident in the budget and the contingency.

Read Utility Week’s analysis on the Thames Tideway Tunnel here.