Boreholes

[Maizefarmer]

BOREHOLES

Lots of us have water boreholes and there are some of us who would like a water borehole.

But you get boreholes and you get boreholes i.e. some will work good & proper for a long time, and some will be nothing but trouble trouble trouble….because the borehole industry in Thailand, like all industries, has its “cowboys”.

Some things you can do and some things to look out for when selecting the right man to do the job.

1) Jump in the pickup and drive around a bit – check out who else around you has a borehole and have a chat with them. Find out:

- how deep the hole is

- how much water it produces p/day

- is it year round (or if it changes, by how much does it change).

- what pump do they use (submersible or plunger type – down to around 10m you can get away with a plunger type, much further you’re best off with a submersible, they are more expensive)

- how long has it been in use

- lastly, who bored it and what did it cost.

Check out as many as you can around your village/area – that will give you a realistic idea of what you can expect to get from a borehole on your land. You may even want to get a sample of the water and test it yourself for nitrates/nitrites/ calcium ect ect (done easily & cheaply). If its just for the house and garden 3 cubic meters volume a day is fine – which you can pump out with a couple of truck batteries if you have no ac mains power. Yup, so boreholes in rural areas do make a lot of sense.

Generally you have 2 sizes in Thailand: for domestic use you don’t need more than a 6” diameter borehole, but for agriculture use and small businesses you want 12” diameter borehole (that’s not to say 6” won’t do – it can, and often does – just that you’d be better off volume wise if it was 12” diameter).

Check too if you need permission – some areas you’ll have to go off and have a chat with the local Phu Yai (village head or District Head at the local district office, and in other areas no-one cares) – but check. The only time you’ll get a “no” answer is if you’re in an area that is surrounded by industry and the ground water is known to be not safe, or if there is a ground water quota in your area which is been exceeded (there some areas around Bangkok like that, where some industries lift large quantities of H2O from the ground, but out in the “sticks” I have heard of no restricted areas for quota based reasons).

Now’s the time to have a chat with the guys who dig the holes – and to take note what you have been told by others, compare it carefully with what the borehole digger tells you – because they can tell some tall stories – for every 10 boreholes dug, at least half of them won’t be serviceable after 5 – 10 years and its usually because they weren’t dug properly in the first place, not because there isn’t any water.

So what are the problems:

1) Slurry Slurry Slurry – other than fuel it’s the boreholers biggest expense, but it’s the most important component in boring. It will determine how long the borehole lasts and it will determine how many times you have to lift your pump to take stones out the impeller or indeed, replace your pump. The slurry is a mud that is injected down the hole and (because of its density) is used to lift all the loose dirt and in particular the stones, out of the hole as it is sunk. A lot of cowboy borers just do not use it because it cuts their expense. It must be used. It also ensures that the side of the hole are consistant – it will seep into the uneven side wall forming a consistant smooth surface which consolidates the wall and helps to prevent it from collapsing in over time – nothing worse than having a borehole wall that has collapsed in at 30 meters and compressing part of the tube wall – stopping you from retrieving your expensive submersible pump to get the stones out the impeller! So when you go round to see the guy (always best to go & see him first – and then follow it up with a meeting at your place), just look around his yard to see if there are slurry settling tanks lying around. If he uses slurry he’ll have settling tanks lying around because they like to collect it as it comes up, let it settle and pump it back down again. No tanks then ask him if you uses slurry. If he says not needed, then move on. IT IS NEEDED to do the job properly – simple as that.

2) Borehole tubing –you get borehole tubing and you get borehole tubing. The cowboys will use the thinnest stuff they can get away with. Go check out the tubing yourself – get a quote from the boreholer, then ask him what the tubing costs, get that taken off and go get it yourself – so you know what’s been used and get advise from the hardware store as to what is good tubing and what is not. Don’t skimp on the lining.

3) Joining the tubes in the hole: 3 methods – threaded, screwed, pvc adhesive. Use screws and you are asking to be screwed. They will rust if not stainless steel, which will mean if ever you have to lift the lining you will not be able to. If not correctly screwed in they can break, or just as bad – as someone else has reported: they stuck through so far into the hole in his case they prevented him from getting the pump down the hole. The sharps ends can also wreck havock on the power supply cable in the hole over time. PVC adhesive would be a better choice, but again, it’s adhesive strength can breakdown over time which again will prevent you from lifting the tubes if you ever need to. End threaded tubes are the best – they form a good tight joint and wont separate.

4) Dropping the pump: if using a submersible use 2 (TWO) stainless steel wire cables – not one. If one snaps you’re buggered – try lifting a 10kg submersible from 30 meters on it’s power cable. Not wise. Use two cables so you have redundancy and ensure they are stainless steel not normal multi-strand wire steel.

5) Who to use: well, I assuming you have been speaking to the locals who have boreholes and they have all had theirs done by the same guy and they have all been going for 5 or 10 years,, then I guess that’s a fair bet. But failing that, and having understood all the above will be adhered to, what else: well, ask the guy if he has hydrology maps for your area. All the professionals will have maps and water table data for your area and will be able to tell you the mean, low and high water table levels for your area, season to season for the last 20 years – something that has been and is monitored very carefully by the authorities all over Thailand.

6) Get a good concreate cap poured around the borehole at ground level – and have a lockable cap on the top of the tube (to stop rubbish getting into the tube and someone nicking your submersible pump – they do get nicked).

How deep will your borehole have to be – well, about as deep as those around you who have boreholes, but there is no average – each area, depending on its elevation above sea level will have its water table at a different height relative to the surface – and will be affected by the geology of the region. Some areas are as shallow as 6 – 10meters for good all year round water supply, and in other areas (like where I am) you have to go down 80 – 100 meters to get year round water. Clay areas shallow, chalky areas deeper, and the deepest boreholes are found in the sandstone and granite areas – which also give the best water as the sandstone acts as a brilliant filter. Chalky areas make the water real hard with calcium.

If anyone has their own “borehole experience” to add – go ahead.

Tim

[Jimbo551]

Excellent post Tim. Very useful advice. Thank you.

[Rinrada]

Yes ...very good post......now wheres my drilling machine...?

[geoffphuket]

Anyone have a rough idea how the cost compares to putting in a well. I'm pretty fed up with my water supply being turned off 12 hours a day. I've only a small garden so a bore hole would make a lot of sense.

[Jimbo551]

Anyone have a rough idea how the cost compares to putting in a well. I'm pretty fed up with my water supply being turned off 12 hours a day. I've only a small garden so a bore hole would make a lot of sense.

Depends on how deep and what they have to drill through to get to the water. We did one about two years ago, 2-3 metres top soil, 10 metres sandy clay then 30 metres of granite. Baht 336,000.

This followed a ground water survey which cost Baht 60,000 and we had a full geophysical report so we knew where and at what depth the water was. Get 20cum/day.

[geoffphuket]

Anyone have a rough idea how the cost compares to putting in a well. I'm pretty fed up with my water supply being turned off 12 hours a day. I've only a small garden so a bore hole would make a lot of sense.

Depends on how deep and what they have to drill through to get to the water. We did one about two years ago, 2-3 metres top soil, 10 metres sandy clay then 30 metres of granite. Baht 336,000.

This followed a ground water survey which cost Baht 60,000 and we had a full geophysical report so we knew where and at what depth the water was. Get 20cum/day.

Oh dear, a local Thai mentioned to my wife that a well wouldn't cost more than 10,000 Baht including the pump and cememt rings. Guess I'm back to plan A

Cheers for the information

geoffphket

[Maizefarmer]

Baht10K = No No - not likely, but Baht360K - thats high but it was the 30 meters of granite that pushed that price high.

Look at around Bht50K for a 20 - 30m hole and Bht 100k for 50 - 100m.

Those are very rough figures - which are influenced a lot by what has to be bored through.

Just by way of interest that 30 meters thorugh granite - would I be correct in assuming it was bored through using not a mechanical drill but high pressure water jet (i.e. truck with very big compressor on the back)?

Tim

[chownah]

For those Americans who are puzzled about what a bore hole is and what a well is.....in the US where I come from, a well is a hole in the ground that you make to pump water out of. If you drill a hole in the ground to do this then we call it a "drilled well" and if you use a digger to do this (clam shell, specially adapted back hoe, or a shovel and muscle) then its called a "dug well".....or course if you dig a pond to get water that's not considered a well at all and I won't try to define the difference between a "dug well" and a "dug pond"....but its usually obvious when you see them side by side!!!! Anyway, a "bore hole" is a "drilled well" in American lingo.

MaizeFarmer's talk was really good for drilling wells (makeing bore holes) when the water in your area is very deep...but in some areas (like where I live in the North) it is relatively near the surface and the conditions do not require a lot of the equipment and cautions he mentions. Before describing how my well in Thailand was drilled I want to say that I had a well drilled in the US and we did have one cable attached to the submersed pump but the pump itself was screwed onto the pipe that carried the water upward so hoisting the pump was actually done by lifting it by the pipe....and the one cable was the backup method......galvanized one inch pipe...very sturdy....the pipeing weighed more than the pump I think.

So...on to my Thai well experience. Where I live water can be reliably obtained in a seam of white sand that usually lies from 7 to 9 meters deep....but this seem of water bearing sand is pressurized somewhat so that when the well is drilled the water rises to about the ground water level as near as I can tell although I haven't monitored this throughout the year. Because of this we do not have a submersible pump....just a straight centrifugal pump mounted topside and pumping out of a one inch pvc pipe that goes down about 9.5 metres with a check valve (one way valve) on the bottom.

Before hiring the driller (a man who lives just up the soi) I did like MaizeFarmer said and checked out the other wells in the neighborhhod for depth, volume, and quality of water...luckily he had drilled them all...so everything checked out good...and then I found out that for 2,500 baht he would do all the labor AND HE GUARANTEED WE WOULD GET WATER OR HE WOULD DRILL AGAIN FOR FREE......well....this clinched the deal for sure.

The drilling....I picked the spot.....he brought a two wheeled walk behind tractor with a front mounted centrifugal pump, suction and discharge hoses, steel screw together pipes (about 1.5 or 2 inch...I forget) and the couplings to screw them together, and a home made digging bit he screwed onto the bottom of the first section of pipe. The diggin bit just had some steel projections around it so that it could pulverize the dirt around it so that the dirt could be removed......there is no (or very few) large rocks in the ground here....some gravel but mostly very hard clay and clay with gravel. He use only water (no slurry). He puts the digging bit on bottom end of the first pipe and the discharge hose from the centrifugal pump on the other end and pumps water through this while it is held vertically so that soon the bit is sitting in a puddle of mud....he and his helper start to twist that pipe (and the bit attached) back and forth causing the digging bit to pulverize the dirt which gets washed out by the water being carried down by the pipe. The excess water is collected in a sump hole which he dug by hand (10 minutes work) about two metres from the bore hole so the water emerging from the borehole flows into the sump and the pump suction line takes the water out of the sump....so you can see that the water gets recycled....the dirt coming up from the well settles out in the sump and gets removed as needed. So...he just keeps rotating the pipe back and forth and the weight of the pipe puts pressure on the digging bit and as dirt is removed and washed out by the water flow around the pipe the bit and pipe sink lower and lower....when the pipe is all the way down then another section is screwed on and the process continues. He monitors the dirt as it comes up with the water and when it comes up with white sand he knows he's hit pay dirt...errrr pay water! So then he goes a bit further and he pumps some water out to see if there is enough flowing in....and.....there wasn't......so he says...."mai dee...I'll come back tomorrow and try again!"!!...only he says this all in Thai......and......sure enough he came back the next day and we hit a good supply of water and so he then installed the 3 inch pvc pipe which I supplied for the casing (linging).....3 inch is the largest diameter he will do. He put some verticle slits in the end of the casing at the level where the water bearing sand was so the water could flow in quickly and a piece of wood on the bottom to keep dirt from being sucked up I guess....I was kind of worried about the wood but he said that all his wells were done this way and it is no problem...so OK...

I've never run out of water...I can run a strong hose as long as I want....BUT....you should be advised that the amount of water your well will deliver depends on the conditions where you live and just because I'm fortunate enough to have an abundant supply of water near the surface like this does not mean that you will get the same results...that's why MaizeFarmer started by saying to go check out what the wells in your area are like.

Chownah

[RamdomChances]

Good topic, I've "pinned" this.

I'll add my experiances. I've a 6 inch dia bore with a 2hp submersible pump I can pump around 10 cubic meter/hour (rough figs) based on how long it takes the tank to fill. My tank is about 16 cu/m and water is gravity fed to the house and farm, apart from when using the sprinklers (4hp pump). We had to go down about 60m

First just to add what others have said, go around your local area and talk to people who already have a bore or well (just for defination when I say a well I mean a big dug hole in the ground, a bore being 6-12 dia drilled). Find out how deep it is, who did it, how much it was ect.

I'm not sure if my driller used the slurry, I never even knew about it before reading tim's post. Ours also offered the "drill again if they did'nt find water" garentee. I would imagine this is only avalible in areas where they are pretty certian they are going to hit water. I can't imagine someone drilling through 30m of granite on the off chance.

Depth, size and type of pump will affect the price, I think ours was around 70,000 with the pump, concrete cap and fittings. my tank is made with 2m circular rings

It's not leaning honest, just looks like

Wells are much cheaper so I've heard but only sutible it the water is near the surface.

An other point is always get you well or bore dug in the middle of dry season when the water table is at the lowest, this is what I've been told anyway.

[Maizefarmer]

Yes RDC thats right VERY IMPORTANT POINT -

GET YOUR BOREHOLE (or well) DUG AT THE END OF THE DRY SEASON.

Thats when the water table will be at its lowest (i.e. get to the water then,is pretty much an insurance that you will have it all year round)

- had to leave someting out

Tim

[khunandy]

Yes ...very good post......now wheres my drilling machine...?

http://hydra-jett.com/

Anyone near Khon Kaen want to go in shares and give it a bash??/

[kiwiTV]

Yes ...very good post......now wheres my drilling machine...?

http://hydra-jett.com/

Anyone near Khon Kaen want to go in shares and give it a bash??/

I got a neighbour to drill bore hole for me in Lopburi (stone area). He guaranteed I only pay 4,000 baht if he gets water otherwise don't have to pay. He spent 3 days drilling with a honda motor and a tuktuk differential and gear box adapted for a carry around drilling rig. The system was light and portable and I am sure you could find someone in Thailand to make one up for you.

Might be cheaper than importing something in from America.

[bannork]

We were charged 10,000 baht for a borehole that went down 40 metres about 8 years ago. At that time we had no electricity in the fields so we used the handplough with a belt on the pump method. Now we've got electricity we're using an electric pump.

I want to water about 7 rai of grass so I'm thinking of buying one of the big blue plastic tanks, raising it above the ground on a concrete base, then running underground pipes to the fields with valves at intervals on the surface. It seems better than buying 200 metres of green, plastic hose which will probably split within a few months with cows walking on it etc.

[TBWG]

Interesting read, and yes I know I am in the farming forum and I only use it for watering the garden, but what do I have if it is not a borehole?

Approx 2inch diameter hole (I assume it is lined) with an Hitachi electric pump which is attached to the usual blue plastic piping which is inserted in the borehole.

Drilled in an afternoon by locals who only charge if they hit water. Think they went down in excess of 30 meters and could not have charged much otherwise i would have remembered how much!

Is this just a smaller version of borehole with surface pump as opposed to submersible which is for more commercial use?

The water that comes out is only fit for garden as it has a heavy magnesium content (good for plants but no good for a cuppa!) If I went deeper would I hit water more suitable for domestic use or is it possible for current supply to be filtered so it is suitable for home use?

Thanks

TBWG

[Jimbo551]

Interesting read, and yes I know I am in the farming forum and I only use it for watering the garden, but what do I have if it is not a borehole?

Approx 2inch diameter hole (I assume it is lined) with an Hitachi electric pump which is attached to the usual blue plastic piping which is inserted in the borehole.

Drilled in an afternoon by locals who only charge if they hit water. Think they went down in excess of 30 meters and could not have charged much otherwise i would have remembered how much!

Is this just a smaller version of borehole with surface pump as opposed to submersible which is for more commercial use?

The water that comes out is only fit for garden as it has a heavy magnesium content (good for plants but no good for a cuppa!) If I went deeper would I hit water more suitable for domestic use or is it possible for current supply to be filtered so it is suitable for home use?

Thanks

TBWG

You can get relatively cheap Reverse Osmosis equipment now which will clean the water for you.

[Templer]

My In Laws have just had a bore drilled

went down 30m and cost 25000 bht

Pump included.

Of course muggins had to pay,

Now mother in law and sister in law are arguing

over who pays for the Electric.

[bannork]

My In Laws have just had a bore drilled

went down 30m and cost 25000 bht

Pump included.

Of course muggins had to pay,

Now mother in law and sister in law are arguing

over who pays for the Electric.

I expect muggins will be!

[phibunmike]

I had always assumed that for more than 10m you would need a submersible pump. However our 30m well was fitted with a "deep well" pump on the surface. It works by pumping some water back down as far as I can tell.

We drilled in the dry season, the guy hit water shallow but kept on going until he was satisfied with the cleanliness of the water coming up (tested by looking at it in a bucket).

Touch wood, no problems so far, though from the smell of the water first thing in the morning I think it has a high iron content. All in was about 10 - 20k I seem to remember....

[chownah]

I had always assumed that for more than 10m you would need a submersible pump. However our 30m well was fitted with a "deep well" pump on the surface. It works by pumping some water back down as far as I can tell.

We drilled in the dry season, the guy hit water shallow but kept on going until he was satisfied with the cleanliness of the water coming up (tested by looking at it in a bucket).

Touch wood, no problems so far, though from the smell of the water first thing in the morning I think it has a high iron content. All in was about 10 - 20k I seem to remember....

You are correct that a pump which works by sucking water up the pipe can only pump from about 10m and no more. The pump which you describe is called a "jet pump" in the US. They work by pumping water in a small pipe down the well at high pressure which then powers a venturi which gives the oomph needed to push the water up the well pipe. Jet pumps are less efficient than submersible pumps but they are cheaper and I believe you can operate a jet pump in a smaller diameter well casing.

On the other hand...water which is found in porous layers in the ground are often (usually) under pressure and even if your water is coming into your well at 20m (for example) it could be under pressure and it will rise up inside the well casing. In my well for instance the water comes in from a sand layer at about 10 or 11 metres down but it rises up to between about 1 to 3 metres from the surface depending on the season (dry or wet). Because of this the pump which we use is a common centrifugal pump which sucks the water up the pipe and this works fine because really it is only pumping the water from about 3 metres or less.......which works fine.

[Ed.Lee]

Hi all this is a gem of a find for me, thank you for the posts so far.

Ok here is the thing.

My wife and I (got married today) *Grin, well we have the offer to buy 13 Rai of land near her home village, the deal is quite good for the amount of land but my hesitation is that they only farm rice there once a year because of the water shortage. The village is near Sisaket and so mostly its dry as a sand dune. Can anyone give me an idea of what kind of set up I would need to water 13 rai of land, or at least some of it?

And also if anyone knows of borehole drillers in that area?

I saw the link to the http://hydra-jett.com/ (nice link thanks)

But until I can find out about water tables in the area etc I dont want to go spending on a drilling rig.

(Mind it would be nice to have in the shed.)

I don't know about rice growing yet, so I have some homework to do on how much water it takes to see if its a viable crop, but any help would be appreciated.

Many thanks

[RamdomChances]

Hi Ed

I'm not really sure of the viability of irrigating 13 rai of rice with a borehole, mostly they they irrigate rice paddy from canals or rivers.

As for drilling companies your probaly better to ask around localy, find out if other people have one and who drilled it and start from there. The chances are if no one has one then it's for a reason.

Oh congrats on the marrage

[chownah]

If no one is raising rice there now (during the rainy season) it is a good bet that it is not practical....I could be wrong on this but it seems to me that all of the rice land that can produce rice with the current irrigation canals is already being used. I'm not sure but I think that if you had to pump all of the water for rice that it would not be practical...unless you only had to raise the water a very small amount...like one metre or so....but again I could be wrong on this.

Mostly I see people using the large diameter tube pumps (which can not be used in a bore hole...you've got to have a pond or river for these) to water other crops which require less water and generate more income per rai than rice. I could be wrong on this though so you should ask around. I have a tube pump and use it mostly in the dry season to water other crops...not rice. In a very dry year I may use the tube pump to get me through a short period when no water comes in the irrigation canal and no rain falls especially if this should occur when the rice plants are flowering or making the grain.

Chownah

[RamdomChances]

^ don't you need to flood the paddy as some point ? By my reconing to raise 13 rai by just 1cm would take 208 cubic meters of water, just don't think it wold be possible with a bore, it would have to be pumping 24hrs a day.

Oh I think you should do a post on rice farming as we have'nt got much on it

[Mobaan]

That is how all the rice (millions of acres) is grown in the Mississippi Delta.Often pumping 24/7

[chownah]

That is how all the rice (millions of acres) is grown in the Mississippi Delta.Often pumping 24/7

Mobaan,

Isn't the Mississippi delta a flood plain so the water table is nearly at ground level? Any idea how much they need to lift the water? The less verticle distance you need to lift the water the more practical pumping for rice becomes and the higher the water table the lower the rate of infiltration (usually) and the more practival pumping for rice becomes. I'm not disagreeing with what you have said...I'm just wondering if you have any figures on pumping heights and water table height.

Chownah

[Ed.Lee]

Ok lots of interesting posts, many thanks.

As I said they have rice growing now, thats the only time of the year. There is a large resivoir/lake thing but even that isn't used for irrigation and unfortunately for me the preposed land is in the opposite direction. I am looking at trying to secure some of the land near the resivoir. Will make life a hel_l of a lot easier.

The thing is, most of the villagers dont work for most of the year becasue there is no water for crop growing, I hoped that if boreholes were possible it could lead to a injection for the local economy.

*Shrug, We will come up with some sort of plan.

I always do, even if its completely different to the origonal one.

*Smile

Thanks for all the help peeps.

Any further advice is welcomed.

Blessings

[chownah]

Ed.Lee,

Rice takes ALOT of water. That's why the borehole is probably not practical for rice cropping. There are lots of crops that don't take so much water and if you can develop a bore hole I'm reasonably sure that there would be some crops that you could do economically.

The economics of irrigation is partly driven by the cost of the power to do the pumping whether it be electricity or diesel or wind or solar. The higher you must lift the water from its surface in the well to the surface of the land the more energy it will take and so the more will be the expense.

To know which crops you could grow you must first know how deep the water must be pumped from and how much water you can reliably pump at the time of the year you will be growing. Even a well that produces abundant water part of the year but not in the dry season might be beneficial in that it could give you a short extra season at the end of the rice season even if it dries up completely in the dry season....but of course the more marginal the water supply the more marginal will be its usefullness.

Good luck and keep us informed.

Chownah

[Ed.Lee]

Thanks chownah and everyone else too.

I am off to Laos tonight for a visa thingy and once I get back the wife and I are off to Sisaket and I'll do some info gathering.

Have a good week and be safe.

Blessings

[kiwiTV]

The water that comes out is only fit for garden as it has a heavy magnesium content (good for plants but no good for a cuppa!) If I went deeper would I hit water more suitable for domestic use or is it possible for current supply to be filtered so it is suitable for home use?

Thanks

TBWG

You can get relatively cheap Reverse Osmosis equipment now which will clean the water for you.

High in Magnesium will block up your RO membrane very quickly.

[Ting Tong Man]

I did see any mention in this thread about using a sand or gravel pack around the well screen. Is that not done in Thailand?