Monday, October 12, 2009

Spring-water questions and answers

Tackling problems concerning a spring is fascinating, because you're faced with challenges of a primordial earthly kind, like those that ancient settlers had to deal with. Over the last few days, working at times in the style of a backyard archaeologist, I've even discovered elements of the ancient solution to the spring-water challenge at Gamone, along with subsequent modifications that can be described retrospectively as a blunder. My spring, 50 meters up on the slopes behind my house, can be represented as follows:

The red object is a closed cemented-stone receptacle that takes in spring water through a hole on the left, and lets it flow out, down towards the house, through a flexible rubber tube on the right. The presence of this compartment ensures that the water will be relatively clean, that's to say, free of mud and floating vegetation (since there's an iron lid at the top of the receptacle). Besides, the right-hand wall of this receptacle enables the rubber outlet tube to be held firmly in place, and sealed to prevent leakage.

Down at the house, during the eight or nine months of the year when there's water in the spring, I simply leave a hose running non-stop, watering the lawn, garden, vegetation and fruit trees. On the other hand, since my house is linked to the municipal water supply, I don't use the spring water for domestic purposes... apart from occasional tasks such as washing the car, mixing concrete, etc.

There is, however, a hitch. When the level of water in the pool is relatively high (as in the above diagram), there's a major overflow from the embankment below the spring. The quantity of leaking water is such that it's like a second hose emerging from the base of the spring. Up until now, I've never understood why this overflow occurs, nor where exactly the water is leaking. Since the surface of the pool never rises to the top of the receptacle, it's not an overflow in the normal sense of the word. It's rather a massive leakage from somewhere inside the pool. But it's definitely not seepage from the bottom of the pool, because there are long periods during which water continues to flow abundantly from the hose at the house, whereas the leakage at the base of the spring has stopped. Pierre Faure, the municipal employee, concluded therefore that the seepage probably occurs through cracks and crevasses around the upper edges of the pool. In other words, the water level in the pool has to attain a certain minimum height before the seepage starts.

Other rural friends have suggested that maybe the diameter of my outlet tube is too small. To me, that never sounded like a plausible explanation. After all, I imagine that the flow from this rubber tube was perfect for the former proprietor of Gamone who had installed it, before the arrival of the municipal water supply, in order to bring spring water into the house by means of a single tap in the kitchen... which still existed when I first discovered the dilapidated house in 1994.

I ended up considering that, since I was unable to explain the origin of the leakage at the base of the spring, I would have to "live with" this fault. Consequently, I imagined a makeshift solution that would consist of "capturing" the leakage in some kind of a drain, and bringing the water down to the house by means of a second hose.

Yesterday afternoon, by a mixture of logic, chance and some digging in the mud, I finally solved the mystery. I discovered that there's a much bigger outlet hole, concealed (but not plugged) by the earth wall, further up towards the top of the receptacle, as shown here:

This is almost certainly where the leakage occurs, allowing a large volume of water to flow down a subterranean path to the base of the earth embankment, where it emerges and flows onto the road.

Now, the obvious next question is: Why does this big hole exist in the upper wall of the receptacle? In fact, it was the initial outlet, no doubt installed by the monks who made wine here before the French Revolution. This hole was the start of the ceramic pipe system that used to run down the slopes to the house. Here's a fragment of one of these pipes, partly clogged up with a calcareous deposit:

Much later, when the level in the pool was low, a farmer must have decided to replace the ceramic pipes by a narrow rubber tube. And the lazy fellow didn't even go to the trouble of blocking up the initial outlet. For me, this is fortunate, because I now intend to abandon the rubber tube (which is regularly blocked up with mud and weeds) and bring the ceramic-lined outlet back into use.

Now, my explanations must sound simple and boring. What you have to understand is that the real context in which I've been tackling this problem is both messy and muddy. Let me show you some photos.

That's the receptacle, with the lid raised. The next photo gives you an idea of the pool, surrounded by vegetation, to the left of the receptacle:

I've been using the green hoe to take out some of the accumulated mud, which I intend to use as natural fertilizer for my rose bushes. And here's the outside wall of the spring, where you can just make out a crowbar (beneath the power tool) stuck into the ceramic-lined outlet that I had just unearthed:

Why is this an important preoccupation for me? Two reasons. First, if I don't succeed in halting the leakage from my spring, it could bring about a landslide on the lower slopes. Second, as soon as I succeed in mastering the flow from the spring, I want to store the water in an artificial dam, below my house, and use it to irrigate my rose garden.

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