Going underground

Today, work began on driving the hollow steel tubes into the ground. A total of five have been buried so far:

I'm assuming that the concrete gets poured into these. Work on these is still scheduled to finish on Friday, allowing the break to be used as setting time. Highly efficient.

Here's a closer look at three of the pipe-tops:

I'm a bit concerned by the fact that the one furthest back here, beyond the yellow buckets, will be supporting the side passage rather than any of your actual walls. Still, I'm sure that they know what they're doing, and I know they have insurance.

The original specification had been for eight metres deep, but we learned today that this has been changed to twelve metres. Thankfully the extra cost is minimal.

I don't know if this is the full twelve, but it's further than my camera flash goes.