Running a French Holiday Gite in Rural Brittany

Wednesday, October 03, 2007

Installation of our new fosse - part trois - Tuesday: digging out and installing the new septic tank

Continuing the story of the new septic tank installation at our French holiday home, after clearing the topsoil, emptying the old fosse and delivering the gravel the next job (after the hour-or-so lunchbreak at the nearby restaurant with a 3-course menu for €15), the next job for Tony and the lads was the septic tank installation.

Unfortunately just as Tony broke ground with the mini-digger it started to rain, and rain, and rain. And as the hole grew, it continued to rain, so the garden stopped being a covered in earth and started being covered in mud.

The 5000 litre septic tank required a hole digging about 2m wide x 3m long x 2m deep, but as the waste pipes had to be sloped downhill from the house along under the driveway to the tank, this necessitated the hole being dug out another 0.5m deeper so in all some 15 cubic metres of earth had to be excavated from the garden. Of course all this soil had to go somewhere so Bennodet (seen in the white coat just behind the mini digger) kept on ferrying it on a mini tracked-dumper from the bottom garden, out of the driveway, along past the house, up the hill, through the gap in the fence, and dumping it at the top of the garden where the filter bed was to go (see this plan for the new fosse system for more details).

Just an hour later the hole was dug and Tony then used the mini digger to hook up a piece of rope attached to the plastic tank, lift up the tank, and carefully manoeuvre the tank into the hole.

And of course it didn't fit - quite. Width and depth were fine, but it was just a bit too snug lengthwise in the hole to enable it to be positioned properly. So some shouting backwards and forwards, taking the tank out of the hole, more digging, and then the tank fitted back in properly.

Nic spent quite a while in the hole carefully checking with a spirit level that the tank was absolutely level and true before they started filling in around the sides of the tank with gravel from off the driveway.

If you look carefully at the photo you can see a greyish line in the soil about a metre down from the surface level, this is the water table level for the area. Our house is fairly close to the River Lie and probably some time ago the valley floor was once part of the meandering river bed - over time the soil level's built up and is now a fair way underground.

What this did mean was that having just dug a large hole in the ground, the water level would fairly quickly start seeping back into the hole and would lift the tank out of the ground as it rose up. Bennodet therefore uncoiled the hosepipe and started filling up the tank with water to prevent this happening.

Tony's final request before they left for the evening was to leave the water running until the tank was almost full (which required most of the evening to do).

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