Setting a pump / valve in a new bore well

H

hinakos

Member
Hi all,

Im in the process of drilling a new well. (started today)

Target Depth is around 50 M

Theres a bit i dont know about a few critical things though, and it seems to vary greatly for tukang sumur to tukang sumur.

Assume my intended well depth is 50M, and the top of my water table sits at around 25M:

1/How far should the well be cased?
2/If using a surface pump (eg Grundfoss JD series), where abouts should the foot valve be placed (in relation to both the casing AND the water table). Wont the foot valve fail earlier if it sits in un cased hole due to particulate ingress?)
3/Same as for above but change surface pump for submersible
4/What is the desirable amount of uncased well to be extended from the end of the bottom of casing?(also in relaton to water table height)?

I realise these are rather technical questions, i've already tried asking many different tukangs these answes vary so greatly that im not sure whos right and whos wrong. Leading me to believe that no one really has a clue.

There are a few threads in pod archives regarding drilling wells etc.....but no one really asks the important questions, most of these posts just refer to depth and cost.

Hinakos
 
Hi Hinakos, I had exactly the same questions. Every tukang I me gave me a different answer. I finally managed to get connected to PDAM by paying extra to get the pipe come to my house from the main road.

I guess you can't get PDAM at your place?
 
already have PDAM but the adjacent hotels have reduced the pressure so much so that the water struggles to flow (dribble) sometimes.

Already have a well too.....just drilling a new (deeper) one.
 
Ok, my tukang was suggesting a well with double casing. The deepest would be 40m and the double casing would go down to 20m. The second casing was meant to be so polluted water from the upper level couldn't contaminate the deeper water.
 
Hi Balibule,

by double casing I assume you are talking about the outer casing (used to line the hole) and then the water pipe itself which is connected directly to the suction side of the pump (and sits inside the outer casing).

So I also assume you mean total well depth is 40M, and both the outer casing AND foot valve finished at 20M


Or do you mean the outer casing finished at a total depth of 40M, and your water pipe and foot valve sat back up at 20M (if using a suction pump).? If so, what was total well depth?

I realise total well depth varies from site to site - but trying to establish the relationship between where the outer casing should end in relation to total well depth , and where the foot valve should be set in relation to the end of the outer casing (in the case of a suction pump)......or if these ratios vary when using a submersible rather than a suction pump


Hinakos
 
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I'm no expert and not sure about the amount of casing but can comment that at that depth you will need a double action jet pump. I watched the tucangs take mine out recently and it consisted of 2 pipes, one larger than the other. I believe the principle is water is sent down the smaller diameter pipe as a jet to create a vacuum at the head and facilitate to lift the water by suction thru' the bigger pipe. My pipes were 50 metres and had to be cut, and re-attached with collars, when replaced.
I think my casing is just a larger diameter plastic pipe that remains intact....even if the head needs to be removed. Sorry.....I've no idea how deep it went.
 
Hi Hinakos, where I'm building the bottom composition is mud (old rice fields). If I was going to make a single casing then there was a chance for polluted surface water (<10 meter depth) to seep down the space between the casing and the mud and contaminate the deep, clean water. That was why I was suggested to have a double casing. I now have PDAM so I stopped worrying about having a well.

My PDAM water pressure is good and if it drops I thing I'll add a water container to slowly fill it with PDAM water and use a booster pump to the house.

Deep Well.jpg
 
Sorry for the crap picture. The original is a pdf file but I can't figure out how to attach it to a post as it is to big in size.
 
Picture is ok - but it looks more like setting casing for a different kind of process than water. Cant tell as cant read the details.

We ended up drilling to 60M. 5 inch hole to accomodate 4 inch casing. Cost = 45,000 a metre.

set casing at 34 M. Casing cost is on top of drilling cost.

set the pump valve back up at 30m (4 m up inside the casing tostop contaminants blocking up the intake). Pump vavle and pump pipes alo an extra cost.

so in effect we have 26M of open hole underneath the casing.

heres the wierd thing: we have an existing well on the property (total depth 24M, casing set at 20m, pump valve set at 17 M). We had that water tested and it camse back no so bad. Choliform was 3 ppm (not so bad for south bali at least). Some heavy metals etc in there which isnt a prob as can easily be removed thorugh filtration.
The purpose of us drilling the new well was for future redundancy - more depth, more open hole to allow greater water absorbrion etc..

When we had the new well water tested (remember its at a far greater depth) the choliform and choli tinja were off the richter...greater than 240ppm (i think its measured in ppm at least). So 80 times more of this nasty stuff in our water well that is at greater depth. They are only 2 Metres from each other (the new and old well)

Didnt want to go any deeper due to salt intrusion possibility.

The guy who drilled the well says he knew when to stop as he was "tasting" the rocks / cuttings that were coming back up out of the hole while drilling.
When they start getting salty he stopped drilling. I shit you not.

So im thinking that maybe all this exposed hole i have under the casing (26M) ....while it also allows for greater absorbtion of water, it also allows more nasties into the well????

I really dont know who to talk to about correct proceedure for all this.

I heard that there is a government office somewhere which has underground mapping of all the water tables in every area of Bali etc...trying to hunt them down as we have also another well to drill.

Basically i think the entire of the south of Bali is contaminated with shit in the water....everyone is bathing in it and swimming in it in their pools. I've since installed a complete water filtration system on my house, but what about everyone else in the south of Bali? Dont know or dont care?

So still looking for 2 things:
Underground mapping of water tables etc. (Rock tasting doesnt cut it for me)
Technical know how on building / setting casing in a well (not drilling...thats easy).

The quest continues.
 
Thank you for the update. I'm now officially connected to PDAM and am happy not to have to worry about what you just wrote :icon_razz:
 
Hmmm, i wonder how a lab test on your PDAM water would go?

I found this:

Well Construction - Well Water Protection and Groundwater Stewardship

lots of useful info....and lots of scary info. i dont think anyone in this entire country is constructing water wells properly, be it in the south of Bali or anywhere else. In the south of Bali however, the concentration of contaminants in the ground to due the number of septic tanks, and the sheer thousands of water wells in close proximity, all poorly constructed, (without well seals to stop surface water mixing with ground water) means that even if you go to the trouble of constucting yours properly, your still hooped as for sure none of your neighbours have. Also means it can never get better.

I dont know of one well in Bali, of anyone ive talked to...that has this "well seal". So were all bathing in poo.

Or am i just being negative?
 
Until the septic tanks are phased out and a proper sewerage system is in place the situation will only get worse. The ground water used to have its own filtration system, it acted like a massive sand filter so by the time it was part of the aquifer system it well and truly treated. As you have pointed out with no well seals surface water is going directly into the system with all the contaminants, one fix would be for all new development to have a rainwater catchment system. In India an aid program was setup to provide poor villages with drinking water by drilling wells the only problem was they never placed casing in the wells and the ground above was full of arsenic, this in turn entered the ground water rendering it unusable, thought was there just the application was floored.
 
kiwi said:
Until the septic tanks are phased out and a proper sewerage system is in place the situation will only get worse. The ground water used to have its own filtration system, it acted like a massive sand filter so by the time it was part of the aquifer system it well and truly treated. As you have pointed out with no well seals surface water is going directly into the system with all the contaminants, one fix would be for all new development to have a rainwater catchment system. In India an aid program was setup to provide poor villages with drinking water by drilling wells the only problem was they never placed casing in the wells and the ground above was full of arsenic, this in turn entered the ground water rendering it unusable, thought was there just the application was floored.
Click to expand...


Ive since found out my guy drilled through the bedrock and didn't use a seal (thus the bad lab test). His excuse...."nanti lama lama akan bagus" "it'll get better later". Lies fly from the mulut before they've even engaged the grey matter. And yes, he had that shit-eating grin when those words were flying.

Solution - drill out the 4 inch casing (carefully so as not to sidetrack and miss the original hole in the bedrock) with 10 inch........then set a new 4 inch casing, leaving 2 inches either side for a cement seal(s) at the correct depth(s). It sounds like there were 2 bedrock layers on the original well drilling so will need 2.

This may not work of course and I may still get bad water if my neighbours have deep wells (past the bottom layer of bedrock) don't have seals. But most don't usually drill this deep so im hoping not.

This of course is my fault as I did not "ask" for a well seal on the original job!!!!!!! So im paying again. This time a whole lot more...10 inch hole is 180,000 a meter, as opposed to 4 inch which is 45,000 a meter. 10 years in Bali and still taking it as deep and as hard as someone who just walked off the plane.

Didn't know it really existed (well seals) until spending hours researching after analysing my original lab results. The previously attached link explains it all.

So what I deduct from all this is that its an "exception" to ask for a well seal, and there are about a million wells in bali which are nothing more than holes in the ground with a length of pipe jammed down them. Either that or my tukang sumur needs a bullet to the face.

And being that I cant find any records of this on the forum, any one whos part of this forum and ever drilled a well already knows all this thus hasn't needed to ask or is also running a combined sewer inlet / water well system.

I'll take the word out of your mouth Markit..................."or doesn't live in the south". Farming run off and pesticides are just as bad so no one is immuned. We get to ingest poo and get ecoli, you get to grow a sixth toe or begin shooting blanks.

Rant over, don't really feel any better.

Except maybe the next person to drill a well asks about this and doesn't fall into the same dirty hole.
 
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Thanks hinakos for the update. Sorry for your experience but you've provided some very helpful information and hopefully others will avoid the same situation.
 
Hi Hinakos,

Thanks for sharing your experience as it is most helpful.

Any chance you could share the telephone number for your well guy?
 
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