In order to design a foundation for the turbine that isn’t going to sink, we have to investigate the subsoil and bedrock of the site. Unfortunately we seem to have chosen the wettest time of year to undertake this, and ground conditions are pretty much as bad as they can be. The photo gives an indication of what we were up against today!
Using technology that probably dates back hundreds of years, a simple rig uses a falling weight to drive a tube into the ground. After each half metre or so is dug, the tube is pulled out the ground and the core extracted. The collected soil cores are documented and sent back to the laboratory for analysis. Desktop research indicated that we should have 20 metres of sticky Crewe Series glacial boulder clay, followed by mudstones, and then sandstones. We didn’t investigate the rocks, but we had 18.5 metres of beautiful uniform clay, no sand and very few stones. So, we have a perfectly predictable base on which to build the concrete foundation pad.
Getting those results was definitely a struggle though. We started this morning by trying to pull the drilling rig out to site with a tractor. We got about 10 metres through the gate before we got hopelessly bogged down. In the end we have had to hire a local contractor with a tracked excavator to haul the rig to site. The poor guys doing the job have persevered all day in the cold and wet mud, but they have come up with the results we wanted to hear!
That’s it, we are now committed. Today I have made a bank transfer into the supplier’s account for the sum of an awful lot of money! We have had to pay 60% of the cost of the turbine before they will take our order and begin construction. It reminds me of a trip long ago to Kenya, where we caught a taxi. The driver’s first destination was a filling station. He couldn’t afford to put fuel in his car until he had a guaranteed customer. I’m not saying that the Dutch manufacturer is like that, and I think all the suppliers work on a similar basis, but it does make you think. (At least it does when you’ve just, as they say, bet the farm!)
