Any Borehole Pump Experience on the Forum?

[trogboy]

Might be one and the same well then. It is possible that it may have been decommissioned by just in-filing the borehole within the perforated section of the screen, leaving a solid lined section above as a void.

If you don’t have any form of pump already and want a cheap way to test the yield is sufficient for your needs then you could build yourself an air lift pump. They are simple enough and I build them all the time at work for developing small diameter boreholes. The cheapest versions use a roll of water supply pipe and some 6 or 8mm nylon air delivery tube, then you just need compressed air. Even a 25 mm one would deliver more than you need for testing the well if made long enough.

You should consider what the draw down in the water level will be at the rate you want to pump at. The faster you pump the greater the drawdown. If it remains small you could even fit a suction type pump at the well head rather than a submersible.

Keep in mind that abstractions exceeding 20m3 per day should be licensed with the Environment Agency in England and Wales. If pumping at 45 l/m that would be used in just under 7.5 hours.

 

[awemawson]

@trogboy If I use 3 cu m in one melting session I'd be surprised, and that's only going to happen once or twice a month so I'' be nowhere near the licencing limit.

I'm interested in how you are constructing your air pump - any chance of a sketch?

 

[Gareth J]

As mentioned, plenty of bore holes are abandoned due to limited flow/poor quality.

Definitely test both before investing further.

Alternatively, who dug/maintained it? Worth some phone calls to previous owner big possible? Might save some time if it's a dead duck.

 

[awemawson]

Originally sunk in 1922 so I don't think that chap who did it is going to tell me much

 

[8ob]

The few I have seen have been a little underwhelming, the one where we are working at will fill the prefilter with sand if you try and extract any more than a hose pipe can deliver.

Bob

 

[trogboy]

@trogboy
I'm interested in how you are constructing your air pump - any chance of a sketch?

No problem. I’ll sketch something up later on. It’s a shame I’m not at work or a couple of photos would tell you all you need to know.

 

[Ton-up]

Can you pump from borehole into into a holding tank and then filter/ pump that at the rate you need?

 

[thinfourth]

I don’t know if i would use a borehole pump for cooling water as its an expensive solution

Also i don’t think its a bore hole as a really big borehole is 12” across I’d class that as a well

And if it is a well I’d be going for the following solutions

1 A selfpriming pump like a cheap DABJET which will suck from about 5 MTRs down and then dump the outlet into somewhere

2 Get a BIG central heating circulator pump and have it draw from the well about 10mtrs down and then return it to about 2 MTRs down. Then get the air out of the system with a hoover/vacuum pump. Then it will draw water from deep where it is cold and dump it back near the top. Providing it doesn’t draw any air then you are good.

3 Throw a submersible pump down it with a really secure rope on it and dump the outlet somewhere or back to the well

4 Leave the water in the well and throw a length of pipe down there and circulate the water around that using it as a cooling coil.

 

[Justme]

How will you dispose of the waste water?

Our borehole is about 50m deep & has a 4" pipe.

We used a cheap CB100 well pump (at the time it was just over £100 now they charge about £300).
Its been 100% reliable so far for about 10 years.
Float switch in a 1500L tank controls borehole pump.
The tank feeds the house via gravity & is then boosted to mains pressure & "fills" a 100L pressure vessel.
Controlled by a pressure switch.

 

[awemawson]

I have roof / surface drains running from close to the location to a stream running though my property. It's about 80/100 metres away otherwise I'd be using he stream for cooling!

 

[trogboy]

Right, let’s try posting an image.



It’s more difficult to use the forum from my phone but hopefully the image will appear.

it should give you the idea of how an airlift pump works. Essentially you have a riser pipe in the borehole or well, open at bottom and open to the atmosphere at the top. You can have it connected to a vessel of some sort, but is needs to have an unrestricted vent to atmosphere at the top also.

With the air off the water level in that riser pipe will be sat at the same level as water in the bore. You then inject air into the inside of that riser pipe which has the effect of decreasing the density inside the pipe causing the water level to rise.

The game becomes creating a sufficiently great density differential that the water level in the riser pipe want to stand at an elevation greater than your outlet, if that happens then water will flow out of the pipe and be replaced by water being drawn in at the bottom.

Volumes of air required don’t have to be huge as you are not blowing the air out, just creating bubbles in it.

For quick cheap and cheerful pumps I tend to use 25mm or 32mm hdpe water pipe for the riser and 8mm nylon airline for the delivery tube, air flow being regulated by a valve in the line. The air line gets taped to the riser pipe every meter or so and the air inlet is formed by drilling an angled hole though the wall of the pipe and poking in the nylon. This is held in place by adding a couple of layers of tape. Obviously the air inlet works better if the injected air is directed up the riser tube, and with the addition of a little heat it’s possible to wrap the airline around the riser and back on itself without kinking, even for 25mm riser pipe. I try to cut the end of the air line at an angle and limit the protrusion into the riser for the type of work that I do incase we draw up gravel. The tape is nothing special. I use 50mm pvc tape to hold the air line in place, but standard width with insulation tape will work just as well.

The suction end of the riser can just be left as an open hole if suspended above the base of a borehole, or you can drill holes into the bottom 200mm of so to prevent the pump stalling if the bottom ends up sitting on the base of whatever it is in.

In a situation of infinitely great recharge to the well, larger diameter risers will produce more water for otherwise equal pumps until air becomes the limiting factor. Also the smaller the lift from pumped water level to the level of the outlet (L) relative to the depth that that air inlet is submerged below the pumped water level (S) the more productive the pump will be. At the bottom end of the scale once L approaches or exceeds twice S it’s really not a useful technique as you generally can’t get enough air into the water to lower the density enough to maintain flow.

It quite common for flow to be limited by the ability of the formation to yield water; the water level in the well drops, making the pump less productive until it reaches an equilibrium where water is pumped out at the rate it comes in.

A couple of points to consider if you think you might like to use this kind of set up to test the well you have; Firstly as a non- ridged system in this format you’ll need to weight the toe to avoid the riser just curling up inside the large diameter well. Secondly and partly related to the first, for deep wells especially the effect of adding the air is to make the riser pipe bouyant and it will want to pop up and out, or in your case potentially coil up. For small diameter wells it just needs tying down, but in an open well a non-ridged pipe would need additional weight again on the toe of the pipe. Obviously the larger diameter the pump the greater the buoyancy forces created.

I hope that’s been of some use. I realise with your shallow water you’ll probably be just as well using a suction type pump from the surface but I thought I’d post this anyway as it may prove helpful to others in the future.

I should also point out that as the compressed air mixes with the water it’s not necessarily going to be an appropriate choice for people looking for a pump suitable for potable water abstraction.

Cheers,

 

[Pete.]

I made a 4" diameter one of those last year for a bit of manual dredging in the Thames. had a lot of suction power in it. Never heard of it being used to actually pump water but I can see that it would be very effective.

 

[awemawson]

@trogboy What a simple elegant solution! Thank you very much for going to all the trouble of that drawing and explanation, it’s much appreciated.

 

[Gareth J]

OK the full story:

I am resurrecting my 100 KVA induction furnace that has been in storage for the last 13 years. The electronic driver and the 'furnace bodes' along with their drive cables are water cooled. I was using an 11 KVA input 39 KVA cooling effect water chiller but it has not survived storage and is a write off. I hit on the idea of using a plate heat exchanger, primary furnace water, secondary tap water. But a tap at 15 litres per minute doesn't flow fast enough for the job, I need 3 times that amount.

The bore hole in the past (bottom of page 4 of the document in that link I posted) has supplied 150,000 gallons per day so easily adequate especially as my usage will be VERY intermittent - probably only a few hours a month drawing 45-60 litres / minute.

The bore hole ceased public supply due to high iron content so no doubt things will get iron deposits, but only the pump and heat exchanger not the furnace bits as it will have a sealed water circulation system.

The FULL FULL story is here :

https://madmodder.net/index.php/topic,13100.0.html

Sounds like a sensible use. Getting water to a decent enough standard to flow through a hx is way simpler than drinkable.

 

[Justme]

I have roof / surface drains running from close to the location to a stream running though my property. It's about 80/100 metres away otherwise I'd be using he stream for cooling!

Discharge licence?

 

[awemawson]

YES

(OK it's a licence to discharge treated effluent which is far worse than ground water !)

 

[Pete.]

I had a job to do once in a water board pumping station. They were doing modifications and needed a 300mm hole through a concrete wall, down inside an excavation. I looked around and the only water I could find was a small stream about 25m away. I threw my little hippo pump in it ran out a hose, and got half way through drilling the hole when I heard someone hailing me from above.

It was the water board guy I was working for warning me that he could issue me a fine for abstracting water from the stream! Luckily it was just his idea of a little joke. I did offer to stop drilling his hole and pack up

 

[awemawson]

A friend and I managed to cut out the frame for the manhole cover this morning revealing a 24" 'wet hole' . I did start pumping but my petrol water pump started playing up, but it got the level down several feet revealing 'man irons' or steps down the initial bit of the bore.

I was more easily now able to push my fiberglass duct rod down the bore - this time reaching 53 metres or 174 foot - this is a very good thing as it is well below the level that the records say that perforated pipe was installed.

I pumped the water down a rodding eye on my surface & roof drain runs that leads to the stream 60 metres away.

 

[Seadog]

A quick fag packet calculatin brings up around 15.5 cubic metres of water if you suck it dry. It would seem to be adequate for your needs. That is unless it's dry at the bottom

 

[Justme]

Its a well not a bore hole.