The garden may look like a first world war zone, but after two weeks all the ground work is finished.
Yesterday the four trenches running out from the house were all finished, with both pipes laid and covered with sand.
Richard did an excellent job in measuring the trenches to ensure that the two pipe runs were balanced. In fact they ended up only about 8 meters different, which is well within tolerance. I’m still not sure whether we would have been better to use a single, meter-wide trench for each pair of pipes. But Diddy the digger was sure that the extra amount of earth to be shifted and replaced would not have been worth it.
Then the JCB could get on with backfilling, checking all the time with a pressure gauge that the pipes are not damaged by flints. This was finally finished by lunch-time on Saturday and I could then go round doing the last bits of tidying by hand.
We now have a much more definite idea of the costs of the whole system.
With the total for groundworks at 4K, this is 2K up on my original estimate, and higher than the impression given by the salespeople in the first instance. This is down to the cost of the work John and Pete had to do my hand in mending broken pipes, digging sections near the house by hand, smoothing the bottom of the trench to make best use of the sand, spreading the sand and maneouvering in the pipes. Add to this the hire of the dumper truck and the amount of sand needed and we get to our 2K overspend. This will bring the total cost of the system to 13K. So without the carbon saving angle, this would only be an economic proposition for a family if they had a good long time to recoup – or fuel costs go off the scale.
Anyway, it’s done. Now we have to leave the garden and the woods at least six months for the earth to settle. Then we can replace some top soil, seed the lawn and re-make the surface of the drive.
Then towards the end of September the new model of heat pump should be available from Sweden and we can see if this all works.