Low vol output after new pump install

[Lew Hardy]

Hello,
Just looking for ideas/experience with similar situations to mine.
We have a well that runs 127'. The well was drilled 30 years ago and due to hitting a very permeable gravel strata of around 2' thickness, no screen was installed. The well made over 20 gals/min and we have always had all the water we need for gardening and general home use. The well has fairly high mineral content of iron, calcium and manganese, which we've never felt the need to treat. We replaced the submersible pump 15 years ago with a Goulds 1hp. 10 gal/min. Recently we experienced pump failure and pulled the pump, replaced it with a F&W 1 hp pump with similar output to the Goulds. The wire, and 1 1/4 water pipe was replaced. It was determined the problem wasn't the pump, but where a wire had been exposed through chaffing against the well casing. So, after install out water output is severely underperforming what we've previously had. I'd guess we are seeing 3 gals. a minute now. The Installer maintains the new pump was placed at the same depth as the previous pump and is puzzled by this outcome. I suggested that perhaps a mistake was made when measuring the new 1 1/4 pipe and have asked him to come back and check how far off the bottom of the well the new pump sits. He has opined that perhaps the minerals in the water have slowed the aquifer flow rate (but thinks this is unlikely)and has no other idea on what could cause this poor flow rate we are now seeing. I really don't want to drill another well, as it is rather expensive in our area and doubt we could drill one for under $30K--- and probably it would be higher.
Anyone have any suggestions?
Is there a treatment for stimulating the gravel at the bottom of the well that could be considered (for example)?
Thanks to all that take the time to respond, it is much appreciated.

 

[Reach4]

replaced it with a F&W 1 hp pump with similar output to the Goulds.

What model number is the new pump?

Consider measuring the current through one of the hot lines at the pressure switch, using a clamp-around ammeter.

 

[Sponsor]

 

[Lew Hardy]

What model number is the new pump?

Consider measuring the current through one of the hot lines at the pressure switch, using a clamp-around ammeter.

Thank you. I neglected to post that the pump's output--before it runs out of supply vol--is certainly in excess of 10gal./minute, and after pumping several hundred gals it runs out of water and that is when I see the low gal. output. Sorry I neglected to explain this import point.

 

[Reach4]

Is there a treatment for stimulating the gravel at the bottom of the well that could be considered (for example)?

NuWell 100 is a treatment for wells. The company that makes that also makes other choices and bigger containers. See https://terrylove.com/forums/index....slower-each-year-acid-cleaning-options.88317/ including #18.

Thank you. I neglected to post that the pump's output--before it runs out of supply vol--is certainly in excess of 10gal./minute, and after pumping several hundred gals it runs out of water and that is when I see the low gal. output. Sorry I neglected to explain this import point.

Sounds like this is not a well for supplying a house.

 

[Lew Hardy]

NuWell 100 is a treatment for wells. The company that makes that also makes other choices and bigger containers. See https://terrylove.com/forums/index....slower-each-year-acid-cleaning-options.88317/ including #18.


Sounds like this is not a well for supplying a house.

Thank you for directing me to a similar well situation. I guess what I'm really asking is there a treatment that can successfully be administered to a well that doesn't have a screen. Although it would seem impossible that the squeezing off of flow rates coincided with the replacement of the pump, after reading the thread you directed me to, it certainly seems the problem could be clogging of the gravel from manganese calcium and iron.

 

[Lew Hardy]

Thinking about this again (which I do a lot), I had, what I hope is an epiphany. Since there is no screen, obviously the water enters from the bottom of the casing. If the pump were placed all the way to the bottom of the hole I wonder if it would act as a plug. If, in fact, this is the case it would close off half of the area available to draw from. Between the restriction this would present-- along with 30 years of collected calcium, iron and manganese-- I wonder if this could cause the sudden loss of flow.

 

[Reach4]

Thinking about this again (which I do a lot), I had, what I hope is an epiphany. Since there is no screen, obviously the water enters from the bottom of the casing.

Many wells only have a casing that goes down part way. The part below is presumably a hole in rock that has some fissures.

 

[Lew Hardy]

Well, I can believe that. Our location, which is an Island that was created around 14,000 years ago is glacial till. Just a big pile of transported glacier debris, with the only rock being erratics brought by the glacier. Not unusual to find wood a hundred feet down hole.

 

[Boycedrilling]

What island are you on? I was at Friday Harbor last Friday and Saturday. Bought a cable tool rig from Mauldin Drilling bright it back to eastern Washington on Sunday. it's on a hole out by !leavenworth now.

yes it's entirely possible that your water bearing formation has been plugged by mineral encrustation. It can be rehabbed , using various acids and chemicals. This is not something that I recommend as a DIY project. Acids take special handling both when they are placed into the well, and same with the waste water when it is removed from the well. A chemical treatment is also benefited by surging and swabbing the well mechanically with a pump hoist or drill rig. I have improved the yield of some wells by 50% or more than their original yield. Some irrigation wells here in Eastern Washington need to be rehabbed every 5-10 years, depending on how fast the minerals build up.

I highly doubt that the submersible pump is blocking the flow of water into the well. Did your pump installer video inspect the well?

 

[Lew Hardy]

Hello Boycedrilling,
Thank you for the input. I'm actually on Vashon an Island created by glacial till, vastly different from the bedrock islands of the San Juans. No, there was no video done, as there was no indication of a problem with water sufficiency. The pump quit because of a frayed wire abraded by rubbing against the side of the well casing. Again, the point that is most puzzling is the coincidence of replacing the pump and then for the first time in 30 years having low water output after pumping a few hundred gallons. This is a well that has always been able to run sprinklers in our small orchard all day everyday 24/7. Then all of a sudden, with the changing of the pump we have run into problems. I'll also comment that when we were cleaning up the well after putting in the pump I was surprised to see some coarse black mineral flowing back into a five gallon bucket I was using. I had never seen coarse minerals in our sediment filter before. Anyway, I'm happy to hear there is the possibility of rehabing a non screen well, as having no knowledge in this area I wondered if this was possible.
Thank you for your comments.

 

[LLigetfa]

My guess is that the initial startup on the new pump may have motivated fine sediment that clogged the coarser gravel.

Is there a treatment for stimulating the gravel at the bottom of the well that could be considered (for example)?

Is the pump hung on a pitless? Is there a means to get full open flow? If so, then hard pumping in short intervals might help if it does more than just draw down the water in the casing. Return a portion of the flow back into the well to keep from running out of water.

Maybe a well driller could setup a surge block to get the fines to move forward. Maybe they could drop a tanker full of water down the well to push back the fines. That may depend on how high the static level is.

 

[VAWellDriller]

If there is ANY question, I think you need to verify the pump depth setting. Your symptoms and the particularly the TIMING of their onset could easily be caused by the pump setting....even a couple feet can make a difference sometimes. What material was the original pump set on, what was it replaced with? If it went from steel to PVC each joint will be 1' shorter.

Knowing the exact pump depth setting, and performing a drawdown test accurately measuring water level will quickly diagnose this as either an equipment problem or a well problem.

 

[Lew Hardy]

If there is ANY question, I think you need to verify the pump depth setting. Your symptoms and the particularly the TIMING of their onset could easily be caused by the pump setting....even a couple feet can make a difference sometimes. What material was the original pump set on, what was it replaced with? If it went from steel to PVC each joint will be 1' shorter.

Knowing the exact pump depth setting, and performing a drawdown test accurately measuring water level will quickly diagnose this as either an equipment problem or a well problem.

Gentlemen,
Thank you for your comments. Yes, there is a pitless adapter, so, the concept of flowing back into the well is most interesting. I measured the poly pipe that was removed and determined the distance from the pitless to the bottom of the pump. I have high confidence of the accuracy of the measurement (126 .5)as I know how to measure stuff, being a Cabinetmaker since 1977. The poly was replaced with PVC coupled with stainless connections. I think my first step will be to lower the pipe string to the bottom of the well and measure that distance. I suspect I'll find it sitting on the bottom and will move it up if that is the case. First I'll determine the static level with a ohm meter. I really appreciate everyone's input.

 

[LLigetfa]

What material was the original pump set on, what was it replaced with? If it went from steel to PVC each joint will be 1' shorter.

Good point. using 20 foot sticks versus 21 foot sticks would set the pump about 6 feet higher assuming only full length sticks.
Scratch that... OP replied while I was typing.

 

[LLigetfa]

I suspect I'll find it sitting on the bottom and will move it up if that is the case.

I doubt that the pump touching bottom would have a negative impact on draw rate but if fine sediment builds up around the base of the motor, it could affect cooling.

What is the casing inside diameter?

 

[Lew Hardy]

The casing is 6" in diameter, and as I commented, the pump is new.

 

[Reach4]

First I'll determine the static level with a ohm meter.

How is that? Lower a pair of wires until the resistance drops due to the open ends being in water?

 

[LLigetfa]

Chances are slim to none that the annular space between the motor and the casing could be plugged up enough to reduce GPM. The flow rate that close to the center would high enough to mobilize fine particles. It needs to be at a much larger distance from center before the flow is too slow for fine particles to be dislodged.

If the pump were much higher up the casing, the velocity of flow on a 6 inch cross-section would be less which could result in a loss of flow due to fine particle clogging. I had that problem with my 6 inch cased well where the bottom 10 feet filled with clay and I had to bail it out and then surge develop to increase GPM. I did so by hard pumping and returning a portion of the flow to the well when needed.

 

[Lew Hardy]

How is that? Lower a pair of wires until the resistance drops due to the open ends being in water?

Yes, that is exactly the way I would do it.

 

[Lew Hardy]

Chances are slim to none that the annular space between the motor and the casing could be plugged up enough to reduce GPM. The flow rate that close to the center would high enough to mobilize fine particles. It needs to be at a much larger distance from center before the flow is too slow for fine particles to be dislodged.

If the pump were much higher up the casing, the velocity of flow on a 6 inch cross-section would be less which could result in a loss of flow due to fine particle clogging. I had that problem with my 6 inch cased well where the bottom 10 feet filled with clay and I had to bail it out and then surge develop to increase GPM. I did so by hard pumping and returning a portion of the flow to the well when needed.

Thank you, I guess the initial normal flow I see is simply drawing down from the static vol. I guess I'll follow the advise of Sherlock Holmes: Eliminate all other factors, and the one which remains must be the truth.
1. Determine static level;
2. Determine exact depth of pump and compare it to pump it replaced;
3. Measure flow test of output (prolonged);
4. Try flow back and dislodging fines at bottom of well.

I wonder if I can rig up a 8' piece of 3/8's rigid copper to squeeze by the pump and jet the gravel at the bottom of the well while pumping. I think I would try this by placing water in a portable air tank and pressuring the tank with air. I may have to rethink this, but it's my initial thought. Heck, I should just have a professional come, but I'm concerned about access for the rig to the well, as things have changed on the property over the last 30 years.