Problem With Artesian Well

[fremmel]

I know this is rare in Thailand but I seem to have a true artesian well. The well is out side of Udon a few km from a ridge of low hills so I guess that's where the water comes from. I hired a well driller to drill a bore hole the day before yesterday. Your basic 4" PVC lined well. In our area it's normal to find good water around 40 meters under a layer hard pan, about a 2 or 3 day job. Yesterday they called and said they found lots of clean water at about 25 meters. I got back to the site and they'd already dropped in some 4" PVC with about 30 cm sticking up out of the ground. And water was coming out of it! A good flow and not just a dribble. I'm guessing in excess of 15 l/min based on pumping out the well pipe and then timing how long it took to refill. All good news so far.

The problem came up today when I went back with some fittings and a hose to divert the water away from where I'm going to start building next week. The well was still flowing with what looked like the same velocity but when I put on the fittings to reduce the 4" pipe to 1 1/2" the water started coming up around the well pipe instead of through it. It looks like I have in excess of 1.5 psi because after putting on the fittings the pipe was sticking about 1 meter out of the ground and water had started overflowing the top of the reducer before it started going around the well pipe.

So what do I do now? The well driller has never had an artesian well before so he's busy thinking on the problem. His first thought was to just pour some concrete around the pipe at ground level. But since the soil is sand with a little clay that would just make the water run out from around the concrete. After talking to him I got a few more details. The soil stratification is that the top 2 to 2 1/2 m is sand with a little clay, about 30 or 40 cm of hard rocky clay (den luk rang which I guess is laterite), 1 - 1 1/2 m of stiff gray clay (den neow), and then about 20 m of hard pan (den daan). The drill rig used the usual spade shaped drill head just oversized from 4". I also found out he only dropped in 8 m of PVC instead of going all the way down.

At this point would it help to line the rest of the hole with PVC? The only other thing I can think of is to dig down to the first hard layer of den luk rang and try pouring the concrete there. Though it seems like the concrete would get washed out first unless I can manage to stuff enough clay around the pipe first.

Any good ideas about how to fix this?

[PaddyThai]

I know this is rare in Thailand but I seem to have a true artesian well. The well is out side of Udon a few km from a ridge of low hills so I guess that's where the water comes from. I hired a well driller to drill a bore hole the day before yesterday. Your basic 4" PVC lined well. In our area it's normal to find good water around 40 meters under a layer hard pan, about a 2 or 3 day job. Yesterday they called and said they found lots of clean water at about 25 meters. I got back to the site and they'd already dropped in some 4" PVC with about 30 cm sticking up out of the ground. And water was coming out of it! A good flow and not just a dribble. I'm guessing in excess of 15 l/min based on pumping out the well pipe and then timing how long it took to refill. All good news so far.

The problem came up today when I went back with some fittings and a hose to divert the water away from where I'm going to start building next week. The well was still flowing with what looked like the same velocity but when I put on the fittings to reduce the 4" pipe to 1 1/2" the water started coming up around the well pipe instead of through it. It looks like I have in excess of 1.5 psi because after putting on the fittings the pipe was sticking about 1 meter out of the ground and water had started overflowing the top of the reducer before it started going around the well pipe.

So what do I do now? The well driller has never had an artesian well before so he's busy thinking on the problem. His first thought was to just pour some concrete around the pipe at ground level. But since the soil is sand with a little clay that would just make the water run out from around the concrete. After talking to him I got a few more details. The soil stratification is that the top 2 to 2 1/2 m is sand with a little clay, about 30 or 40 cm of hard rocky clay (den luk rang which I guess is laterite), 1 - 1 1/2 m of stiff gray clay (den neow), and then about 20 m of hard pan (den daan). The drill rig used the usual spade shaped drill head just oversized from 4". I also found out he only dropped in 8 m of PVC instead of going all the way down.

At this point would it help to line the rest of the hole with PVC? The only other thing I can think of is to dig down to the first hard layer of den luk rang and try pouring the concrete there. Though it seems like the concrete would get washed out first unless I can manage to stuff enough clay around the pipe first.

Any good ideas about how to fix this?

Mate of mine had very simialr problem. He managed to get it sorted after consulting an Engineer. I'll drop you a post as soon as I get to talk to him. In the mean time you might consider where /how you will divert running water from your site.

[fremmel]

For the moment the flowing water isn't too much of a problem. There's a creek bed running through the property about 50 meters to the side and the natural drainage is toward that. But if I can't get it plugged in the next day or two I'm concerned that the water coming up around the pipe is going to saturate the area where I'm going to be putting in the foundation.

[slapout]

Take the reducer off and get orginal driller to run more 4 in. pipe in well, run it to orginal total depth. Pick pipe string about 2 to 3 meter, wrap a piece of burlap sack around pipe, secure with wire or soft line and run back to depth. Warer should flow out top of your pipe as it did orginally. If you dont want water to flow back down beside pipe put a 4 inch L with a lenght of 4 in. hose attached. Then just dump a couple or three sacks of dry concrete mix around pipe. By putting the reducer on the flow restriction was less on the outside of casing so fluid took easiest route. Most people would like to have your problem. Just watch driller 5that he doesnt try to short your pipe again, he fessed up due to him knowing someone was going to find out, when repairs were begun.

[fremmel]

Thanks, that sounds good. Better than trying to plug it with the pipe in place. Because the surrounding soil is mostly sand I think I'm going to have him dig down a couple of meters to the 1st hard layer and put the concrete there. I've already taken the reducer off but since the water had found an easier path it stuck to it and didn't go back to the well pipe. I like the idea of the 4" el and hose instead of the 1 1/2" I'd used before. Eventually I want to reduce it down to the line that I run to the house pump so I don't have to dispose of all that water. But I'll wait for a few days to let the sacking consolidate and the concrete cure. I appreciate the help.

[Maizefarmer]

Well thats real good quality water you have there - pity your well digger didn't do his job properly!!

Yes - I agree with slapouts comments - make absolutely sure he has sunk the tubing right to the bottom of the bore else you are not going to be getting your nice water in a couple seasons time - and when all has setteled and you have the time , throw 1m - 1.5m square 4" - 6" thick concreate cap round the top.

[fremmel]

It seems that the definition of a 4" PVC lined well is sort of flexible in this neck of the woods. An alternate defintion comes into play if you hit den daan. After you hit den daan it you no longer need a liner so they don't put one in. In fact the drill head used isn't actually 4" wide so they can't put it in. I even managed to stay outwardly calm while they were telling me this because the thing is done and we have to work with what we've got. Since he'd brought in a very nice well and everything was looking good at the time I've already paid him. Now I've got no leverage but he's still working to try to fix the problem so I don't really think he was trying to pull a fast one. And I talked to another well driller in the area that's not associated with him and he says around there it's pretty much standard not to line a bore hole through den daan. So, on from here.

We tried digging down to the hard layer but the soil was already saturated and kept collapsing. He had a 6 meter length of 3" PVC with a fitting on the end that brought the diameter up to about 3 1/2". We put that inside the 4" and rammed it into the den daan. That seemed to make a tight fit with the bore hole and stopped the water from running outside the pipe. The 3" pipe sticks up about a meter and there's enough pressure to get a good flow at that point. And the fit is tight enough that even when trying to close the pipe using your hands it doesn't make the water run outside the pipe. We started a siphon out of the pipe with a 1 1/2' hose to keep the water out of the general area. The well flow is strong enough that the 1 1/2" hose with a 1 1/2 m fall is balanced enough to stay in equilibrium. After an hour running like this I measured the output and my guess yesterday was way low. I'm getting just about 50 l/min. A wonderful well if I can just control it.

The plan now is to leave the siphon in and wait three days for the soil to dry out, dig down to the hard layer, and put in a concrete cap. After a few days I'll try restricting the well to see if it's still sealed. I don't really like the idea of leaving the well unlined but it seems to work in this area. And if I tried to line it I'd probably have to go to 2 1/2" pipe or re-drill. So I'll just leave it like this and if I have to re-drill later I won't be any worse off than I am now. Any better ideas are gratefully accepted.

[jaideeguy]

Dig a hole and put in a swimming pool!! free clean water under pressure, you are a lucky man!!

[fremmel]

The thought had crossed my mind. Unfortunately, it won't fit in the budget. Now I'm starting to think about crops that like a lot of water.

[slapout]

To leave the wellbore open (no casing) of course is between you and the man who drilled same. I am not going to say anything else, other than read bore info which has been provided throughout this forum and give it your best shot.

[fremmel]

I've read a lot of good stuff on bore holes here but I wasn't able to find anything about linings in impermeable layers. Googling around I found that it is acceptable to stop lining the well when you get to hardpan. http://envimk.com/mk/index.php?option=com_...8&Itemid=62

is a Thai government site (in Thai of course) that my wife found. She says that it says lining is not needed once you get to den daan. A government publication from the British Columbia http://www.belcarra.ca/reports/Constructio...ivate_Wells.pdf says "The well casing should extend into, and be sealed to a depth of at last 10 feet (3m), preferably to the uppermost layer of hardpan, bedrock or clay above the aquifer." Most of the other stuff I found was more about commercial wells rather than small volume private wells. So, while I would be happier with a lining I'll see how this turns out.

I appreciate your earlier advice and was all set with the rice sacks to do it. But because the first couple of meters is so sandy and it was saturated the sand just kept collapsing around the pipe bogging it in. Digging it out just made the hole wider, not deeper. The pipe by itself would barely move, much less with the sacking on it. So we went to plan B.

If anyone is going to bore a well and they expect to find den daan and they want that part lined then they need to make that clearly understood with their well driller. Because, around here anyway, the drillers don't expect to put it in. I had though by saying I wanted a 4" PVC lined well it was pretty clear but it obviously wasn't. So, once again, TIT.