Deep Well Pump

[StevieAus]

For about the past ten years we have pumped water from a 22 meter deep bore using a Hitachi DT P300 GK Deep Well pump.

The water has always been very clear and without sediment and used primarily for irrigation but also as back up when needed if the local water is switched off.

About 6 months ago we started experiencing problems with the “ foot valve” clogging

We were advised to switch to a submersible pump, we already had a GS brand pump which had never been used.

This was installed and although the volume of water has increased it now contains fine sediment sand/ grit

The only advice received to date is,

1 / the submersible pump is too low in the bore and needs lifting

2/ pump out the sediment/ sand from the bore

As I have no experience or expertise in this area any advice to fix the problem at source would be appreciated 

Thanks

[Gav Bic]

The pump inlet should not be less than 2m above the base of the borehole. If the hole has been tested and there are technical details available the pump can be installed just below the water inflow depth. Sediment is seldom a problem in a borehole as the soil acts as a filter, unless there was insufficient casing installed or a section has collapsed.

[StevieAus]

3 hours ago, Gav Bic said:

The pump inlet should not be less than 2m above the base of the borehole. If the hole has been tested and there are technical details available the pump can be installed just below the water inflow depth. Sediment is seldom a problem in a borehole as the soil acts as a filter, unless there was insufficient casing installed or a section has collapsed.

Thanks for your prompt reply and advice which seems logical to me

I don’t have any technical details as the bore was put in about ten years ago.

I will have the depth to the bottom measured and go from there

Thanks again

[nobodysfriend]

If it sucks in sediments , it is too low .

Lift it up about 50 cm should help .

[sandyf]

13 hours ago, StevieAus said:

Thanks for your prompt reply and advice which seems logical to me

I don’t have any technical details as the bore was put in about ten years ago.

I will have the depth to the bottom measured and go from there

Thanks again

I have been using the same pump on our well for about 10 years, although that is only about 9 metres deep. In that time I have had the valve out 3 times to clean it. last time I put a shroud around it so it sucks over the top of the shroud and not from directly below. As has been said it is simply a question of being too close to the bottom.

Each time it has happened we have looked for someone to clean the bottom of the well but without much success, next time I will probably have to cut the pipe.

[ardsong]

One time we got also a lot of sediment with the water from our 40 m deep well.

We found a cy. in Phrae that came to clean our well with an air compressor and booster vessel. They put a tubed to the bottom and blow the air about 7-8 bar into the bottom. The air will raise to the surface and take the sediment with it. The air will expand while rising and increases the speed of air/water/sediment mixture.

Repeat several times and the water afterwards will be clean again.

Not to say that you have to build a kind of tent over the well head, as the blowing air makes a hell of a mess around.

[millymoopoo]

18 hours ago, StevieAus said:

the submersible pump is too low in the bore and needs lifting

Perhaps so, but the increased flow (suction) may be the problem, drawing sediment from the area around the spear (filter section at the base of the bore).

The spear is usually not fine enough to filter out fine sediment.
If you can get access to a very large air compressor (the type used for jackhammers)  with a 25m hose, try developing the bore.
Remove the delivery pipe and pump from the bore.

Insert hose to bottom of the bore, allow the compressor tank to fill (120psi), release all of the tank (tap full on) into the bore several times, allowing time between each blast for the water level to stabilise.

Stand back as a large gush of water will erupt from the bore like a geyser.

Reinstall the pipe and pump and allow it to settle for an hour or two.

Turn the pump on with the pipe open and watch what comes out, at first it will be filthy drawing out all the disturbed sediment, but it should clear quickly.

Good luck with it.

 

[StevieAus]

23 hours ago, millymoopoo said:

Perhaps so, but the increased flow (suction) may be the problem, drawing sediment from the area around the spear (filter section at the base of the bore).

The spear is usually not fine enough to filter out fine sediment.
If you can get access to a very large air compressor (the type used for jackhammers)  with a 25m hose, try developing the bore.
Remove the delivery pipe and pump from the bore.

Insert hose to bottom of the bore, allow the compressor tank to fill (120psi), release all of the tank (tap full on) into the bore several times, allowing time between each blast for the water level to stabilise.

Stand back as a large gush of water will erupt from the bore like a geyser.

Reinstall the pipe and pump and allow it to settle for an hour or two.

Turn the pump on with the pipe open and watch what comes out, at first it will be filthy drawing out all the disturbed sediment, but it should clear quickly.

Good luck with it.

 

Thanks to all for your responses and advice much appreciated.

[Cake Monster]

OP

A clue to the problem lies n the fact that your water drawn off has fine grit and Sand in it.

The Pump is definitely too close to the bottom of the Bore.

Move it up a Meter or so, in order that when it switches on, it does not disturb the silt at the bottom of the Bore.

Another solution is to ascertain at what depth the Water entry is filling the Bore and too pull the pump up to just below that point.

If you still get a problem, then you have an issue with the Bore Wall not being sealed correctly, and you need to blow the crud out with air, as others have said.

[StevieAus]

1 hour ago, Cake Monster said:

OP

A clue to the problem lies n the fact that your water drawn off has fine grit and Sand in it.

The Pump is definitely too close to the bottom of the Bore.

Move it up a Meter or so, in order that when it switches on, it does not disturb the silt at the bottom of the Bore.

Another solution is to ascertain at what depth the Water entry is filling the Bore and too pull the pump up to just below that point.

If you still get a problem, then you have an issue with the Bore Wall not being sealed correctly, and you need to blow the crud out with air, as others have said.

Thanks for replying and the suggestion your idea seems to be the consensus

Although I have no experience in this area seems very logical.

 

[Cake Monster]

1 minute ago, StevieAus said:

Thanks for replying and the suggestion your idea seems to be the consensus

Although I have no experience in this area seems very logical.

 

Start with Step 1, and monitor the Water quality ( sand / grit )

If ok that is a cheap easy fix.

If not, progress to step 2 

Repeat

Next its step 3 , the most expensive fix

A process of elimination.

As an after thought, also install an inline filter to trap any crud coming from the well that may get into your Water system causing leaks, and seal failures,

 

[StevieAus]

3 hours ago, Cake Monster said:

Start with Step 1, and monitor the Water quality ( sand / grit )

If ok that is a cheap easy fix.

If not, progress to step 2 

Repeat

Next its step 3 , the most expensive fix

A process of elimination.

As an after thought, also install an inline filter to trap any crud coming from the well that may get into your Water system causing leaks, and seal failures,

 

Thanks again much appreciated