They started drilling today for my vertical closed loop field. The spec is two boreholes, 320' deep each. Here's where they're at: 1. First 320' hole drilled 2. They hit water at about 200' but kept on going 3. The pipe is in the hole 4. Hole is not yet grouted since they finished so late in the day. 5. It's raining, not hard, but still raining. Anything to be worried about with the ungrouted hole? Any concern with hitting water at 200'? They had to fill the pipe with water to get it all the way down, since it was buoyant due to the water in the hole. They have a pressure grout truck and are going to pressure grout from the bottom up. Thanks for any input.
I would sit back, have myself a home brew and relax. Let them do their thing. Is there any reason you would have to think that the drillers, or hvac guys on your project need guidance? If not, it will prolly all turn out perfect in the end. Eric
Everything seems to be going smoothly from what you wrote. I would let the professionals do their jobs, that's why you hired them.
Hitting water can actually be a good thing. Water has excellent heat transfer properties, actually better than the ground itself.
You guys are of course correct. I have the utmost faith in this driller to do his job right, or I wouldn't have hired him. The only thing that made me post this is the "head" guy (not the guy who actually ended up drilling the holes) told me a few times that if they hit water he would do more than 2 holes. That guy left after drilling began, and the actually drill operator just kept on going to 320' rather than stopping at around 200 or so after they hit the water. I'm not sure why the "head" guy told me that more than once yet they didn't go that route. He wasn't here to ask last night, hence my post.
I would assume that he is air rotary drilling. Many air drillers are disappointed when they hit water cause it makes a huge sloppy mess. So they like to drill 3-4 shallower bores than 2 deeper bores. Hitting water isn't a bad thing for heat transfer.
Just curious what happens to the grout at the water depth as the hole is filled from the bottom up? ChrisJ
Yes, air rotary drilling. I'll ask the head guy when I see him if this was his point of view as well. It did produce more mess, but not too terrible since the water all drained away nicely due to the slop of the yard.
Pumping from the bottom up forces the water out the top of borehole as the grout is filling the borehole up.
While this makes a ton of sense, it's not what the drillers seem to be doing. They shoved a hose down the hole about 30' or so and started pumping from the truck. They are using a mix of sand and a thermal grout labeled, "Barotherm Gold" (ooooooooohhhh, GOLD). I know it's going in because they went through a large number of bags of each. Second hole is in progress. I think they hit water even earlier this time.
I use Barotherm gold too when spec'd into the plans. I send down our grout line together with the geoloop at the same time ensure we grout from the bottom up. I pull the grout out in 15'-30' increments to keep grout pumping down the hole fast and even. What diameter bore are the drilling? If i drill a 6"x300' bore and use approx 14-16 bags of barotherm with 50-60 bags of sand per borehole.
I talked to the head guy today. He did give me a number for how many bags of each goes down the hole, I don't recall the exact number, but all the bags of sand and grout are down the holes now, so I figure all is well.
I was not trying to add doubt to your mind, just giving you an idea of what involved in the grouting process. By NO means was I trying to make you suspicious of something going on incorrectly.
No worries. This entire process is very interesting to see how this is all done. I appreciate all the input. I'm sure multiple methods exist to achieve the same end result.
