More spring excavation (with pictures!) (by alaric)
After the recent flood, the spring stopped working again. So once more, we went up into the field to try and dig up the pipework.
To recap, last time it stopped, we pulled out the ancient map my grandparents had made when setting up the spring plumbing in the field, and started trying to find either of the two header tanks. We figured that checking the state of the header tanks would be a good way to narrow the problem down. We didn't find either tank, but we did find a part of the pipework. Amusingly, it had a large iron stake nailed through the ceramic pipe, an earthing point for a nearby overhead electricity line. This made it easy for us to life away a broken of shattered pipe and observe a healthy stream of clear water down the thing, indicating the problem was further downhill; but the thick clay was holding the shattered pipe together perfectly well, so we put it back again and carefully packed it down.
Failing to find the header tank in good time, after having spent a lot of time digging around in heavy clay to try and exhume it, we connected a compressor to the pipe where it emerged from the ground by the house, and blew air up it. This caused air to bubble from the ground at a point in the field, but when the compressor was removed, a lot of mud spurted out of the pipe followed by clean water... it had clearly disturbed a blockage. So we considered it fixed for now.
But anyway, recently it failed again. And since there's no mains water available at the moment, this is a bit of a blow.
We tried to find the spot that had bubbled before, since any point where air can get OUT of the pipe is probably a point where mud can get IN and block it, and after a bit of poking with metal rods, we found something that went "clunk" beneath the surface.
Digging down, we encountered a set of large flagstones, which we carefully removed, but beneath was just clay. It wasn't the top of a tank! However, pressing into the clay with the rod revealed more solidness about thirty centimetres further down.
Much digging, and we uncovered a rusty rectangle of metal, surrounded by brick. Clearly the roof of a tank. But while exploring outwards to find the edges, the ground suddenly caved in, revealing a hole:
Interesting. It wasn't very deep, and there was water flowing around within.
A bit more excavating revealed conclusively that it wasn't a hole in the tank, it was where water had eroded the soil away around the corner of the tank. We dug around to find the extent of the metal lid, and lifted it.
(the hole is at the top left, in the shadow).
The tank was full of flowing water, coming in through an inlet then out through an outlet. Indeed, if I stirred up the mud that had fallen in as I opened it, muddy swirls appeared in the stream at the bottom of the hill - coming from beneath the roots of a tree. It appears that the spring water is finding its own path down to the stream, leaving our pipework at some point.
So I dug down to the outflow pipe, and found that it was just emptying into the cavity full of flowing water:
It seemed to be broken and just spilling out into the underground stream! But after clearing out lumps of clay, we found that the outflow pipe was indeed neatly cut into that shape, and was apparently supposed to just empty into a mysterious vertical pipe that, by probing into it with a spike, went about 40cm down into the bowels of the earth:
Sadly, there was clearly a blockage further along, since the pipe was full of water and the spring water was just overflowing from it.
While poking around with the spike to try and gauge what was going on, we seemed to manage to shift something, causing the head of water in the pipe to suddenly disappear down with a gurgle, but then it filled up again. There was plenty still to do today, so we downed tools, trying to arrange it so that nobody could fall into the hole:
Or at least, if they did they'd die cleanly of impalement rather than breaking their leg.
But we're going to need to properly dig down. Presumably, the pipe does a 90 degree bend to continue downhill to the second header tank, and that bend needs investigating, since probing with the spike suggests the shape of a pipe leading away, except at some points the spike went in, as if there were holes in it. But that's quite deep down, so it'll be a serious dig.
And I think we should replace the outlet arrangement with a proper elbow joint - the existing arrangement appeared to have once had stones arranged around it in an approximation of one, but they'd given in and mud had blocked the thing up.
Building Maintenance | alaric | 
Fri 27th Jul 2007 9:45 pm
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