We are still building the large pool near Montflanquin in Lot-et-Garonne - pronounced "Monflankey" in French - we have just started on the paving flags. The weather should be warm enough to screed the pool and install the liner in early April. The experts among you will know that it is very risky to install the screed and liner in low temperatures and so we just build the pool structures through the winter and then have a mad rush in April and May to get the pools finished for the coming swimming season. We will have built another 8 pools since those described in my last post. These will all have to be finished this spring and so we will soon be very busy! We will post some pictures of them when they are fully operational so that you can see what we have been doing for the last very wet and cold 4 months.
I know that you are all interested in the problems that we come across and how we get over them. We have just had a tricky problem with a pool that we are building near Montendre - just to the south of our base here in Jonzac.
The sight is sloping and when Luke priced the project in the autumn the site was very dry and it looked like a very straightforward job as we knew that the subsoil was impermeable clay and so ground water should not be a problem.
We were correct in that ground water was not a problem but the topsoil and the thin sand layer beneath it was totally saturated from all the recent rain. Being on a hillside the pool excavation just filled up with water as it was being dug and all the sand and topsoil was washed into the hole - the construction conditions were just impossible.
So how did we get over this?
We excavated a trench on the two uphill sides where the water was coming from, installed black depannage land drain pipes laid in a 40mm silica gravel bed that was wrapped in a geotextile membrane. This land drain was connected by UPVC plastic pipe that discharged into a disused well. This worked perfectly and enabled us to build the pool in relatively dry conditions. The project was delayed by about 4 days, the cost to the client was less than 2000 euros and he now has a land drain that will keep the pool fully protected from excessive water pressure in wet winter periods.
Because of our engineering background we always overcome such problems at minimum inconvenience and cost to the client - many of the "amateur" builders that install the kits would have thrown up their hands in disgust and walked away from this project.
The middle picture shows the UPVC pipe taking the water away to the old well.
On the other picture the red sprayed line is where the pool walls will be located - the site is now dry and suitable for pool installation. The white material is calcaire laid over the land drain to provide a working surface.
25th March 2007