The cut was not much deeper than 16 inches at the crest. The operator is careful to scrape off our meager forest topsoil (organic layer) into a separate heap.
It will be replaced on top of the subsoil so the forest cover (mostly blueberries and pine seedlings) can recover. Underneath is a ochre-colored clay soil. We give him permission to park his digger in our driveway, because it looks really cool. I'm thinking of getting a bumper sticker, "My other car is a Cat"
While this was happening, we awaited approval from the Board of Health. They needed to check the regulations, as geothermal heat pumps are not that common yet. In some towns where officials are reluctant to expose themselves to any risk of error whatsoever, approving something unfamiliar can take a long time and require a lot of hand-holding. This was not the case, fortunately, for us.
Wizards of Welling, Aug. 3
With the Health Department OK in hand, the two drillers arrived with two big trucks and a pickup in tow. The first truck is the drilling rig itself, loaded with drill segments. I get to hold up the power and phone lines by means of a high technology tool comprised of two sticks nailed together with a "V" cut in the top. The second truck contains additional drill segments and the initial water they need to lubricate and cool the drill tip, until it reaches natural water. This is sort of like a dentist's drill, except on a Jolly Green Giant scale, if the JGG had cavities, but of course he doesn't because he's a strict vegetarian. (And therefore, I think, possibly a cannibal. He's green, right? Or maybe he photosynthesizes.)
The drilling rig positions its drill over the first marked location and unfolds what seems to a skyscraper worth of gantry. Height, to my eye, is way higher than length is long. After some fiddling and centering of something like a huge rubber washer, a drill segment is loaded into position, and insect ovipositors come to mind. (Well, my mind, ok?)
The support truck connects a water hose to the rig. I am told that the drilling is really a hammering of about 6000 pulses per minute, with some rotation, and gallons of water pushed by 350psi compressed air flushing the rock particles to the surface. The water will run away down slope to our cliff, carrying rock dust.
What ensues is about a day's worth of motor noise and vibration, felt right through the bones of the earth. Our dog and the neighbor's parrot (50' down the hill and 100 yards away) take exception to the whole vibrating-earth thing. Fortunately, the bird is not given to repeating what it hears, and you can achieve peace of mind in a standard-issue Golden Retriever via the means of food.
Fact to Forget: I'm told the drilling takes about a gallon of fuel for each foot of depth -- a fact to plug into the cosmic energy equation and then forget because it's peanuts in the larger scheme of things.
A continuous stream of water carries rock dust up the well and down over our cliff. It looks like the streams that flow from glaciers: white and translucent. I thought it was water from the auxiliary truck, but it turns out it's our ground water. The drillers tell me we have enough flow -- about 40 gallons per minute -- to sell it to the neighbors! (We have been told that, like all water in our town, our water is full of iron and, I think, Pekinese -- wait, no, manganese perhaps; fortunately, not arsenic, which is common here and is not good for Pekinese anyway.) The resulting debris from drilling is Pekinese-colored stone dust, which I use to stabilize our crumbling driveway apron up by the state highway.
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