What Does This Indicate???

I have a question for an expert:

Here is a litle background information:
Sand well
Dug in 1978
145 feet deep
4 inch casing
1 hp submersible pump set at 125 feet deep
well produces approx. 12 gpm at 35 psi
used for a sprinkler system and washing autos, etc.
pump is connected to a 40 gallon captive air tank

Other than replacing the pump twice since the well was dug in 1978, this well has never given any trouble. The current pump has been down since 1995.

Now for my question: This past week, my wife noticed a couple of sprinklers were making an audible spitting and sputtering sound. The noise wasn't very loud ............ just barely audible and only doing it every once in a while. Today, I went underneath the house and checked the pressure at the pressure gauge located next to the tank. The pressure was fluctuating between 25 and 35 psi. Normally the pressure gauge reads a stable 35 psi when the sprinker system is running, but not today.

I shut off one of the sprinklers and the pressure immediately stabilized and began slowly rising as I would have expected with one of the sprinklers being off. After starting the other sprinkler the pressure slowly dropped back to 35 psi and began fluctuating once again.

Is this a sign of the well going dry?? (as info, we are in a drought area here in SC)
Lots of individuals are drilling wells lately, Maybe others are tapping into the same stream, which could be bad news!!
However, are there any other factors which could also cause the pressure fluctuation I am seeing????

Thanks so much for sharing your knowledge and time!

I am no expert here, but your own analysis sounds correct to me. If you could get a copy of the well installation record -- I got mine from the installer -- you should be able to compare the original standing water level to whatever you have now and confirm your suspicion of the well now possibly running dry. Or, maybe you could just lower the pump another 5' or 10' and hope the overall water level eventually rises to wherever it used to be.

Update!

UPDATE!!!!!!!

Today, I once again checked the pressure and everthing was normal. At least that is what I found after approximately 30 minutes of continuous running. The pressure was at a STABLE 35 PSI with all sprinklers running.

Now, maybe after several hours of running, I will see the pressure start fluctuating as before. If that is the case, I would assume the well is not able to produce enough water. Is this the correct assumption??

Also, is there anything else that could be occuring which would produce the same type symptoms I mentioned in my first post??

Thanks again!

The static water level in a well varies at least seasonally. You can't use that to tell if the well is sucking air, the spitting, in a 'dry well' condition which is your guess and correct IMO except that you aren't running out of water as much as the pump can't move water, your peak demand gpm, at a higher pressure, from as deep as the water level is dropping in the well when you are watering the lawn.

IMO you need to start water conservation before you end up running the pump dry or find you are out of water for the house; which IMO is much more important than grass that can't survive a drought (I'm not a fan or watering lawns, I'd spread gravel'n paint it green first).

Another Update!

Another Update!

After 3 hours of running today, the pressure has dropped 2 psi and is beginning to fluctuate a very small amount. If you are curious as to what I mean by fluctuate, here goes: The pressure is now at a somewhat stable 33 psi and every once in a while it will drop to approximately 30 psi and quickly recover within less than a second. So, the needle on the gauge moves up and down rapidly when the fluctuation occurs.

The fluctuation I experienced yesterday was the same, except only more dramatic. As you may recall. the pressure fluctuated between 25 and 35 psi. However, yesterday, the pressure was fluctuating about every 10 seconds in this manner.

Gary: We do not use this well for the home. It is ONLY used for the lawn and washing vehicles, etc.

Could this issue be caused by a pump that is possibly on its last leg????? Can a pump do this?? Or, is it just as I have assumed ............ the well can not produc enough??

Thanks again!

Sure it could be the pump and it can be checked for proper amps, ohm and shorts. You can download a manual at IIRC,
www.franklinelectric.com. You should have a 4" submersible.

Verifying Current Draw

OK, so it could possibly be the pump???????? Let me tell you what I have:

I generally check the the curent draw about once per year and record the reading. All readings, since the pump was new, yield a current draw of approximately 9 amps with the sprinkler system running. Sunday, when the system was running properly, the current draw was a STEADY 9 amps.

However, on Saturday, when I experienced the fast pressure fluctuations of between 25 and 35 psi, the current draw was also fluctuating between approximately 8.5 and 9 amps.

So, if a well is unable to produce the exact needs and the pump is actually pumping a small amount of air now and then, would the current draw also fluctuate along with the pressure fluctuatuions????????????????????

Also, if this issue is actually caused by the pump (which would be a good thing in my opinion), how does the "defective" pump create the small amount of spitting and sputtering we hear occasionally????

Thanks again!

Sounds like you need to lower the Pump a little. That should fix it for a while anyhow.

bob...

speedbump said:

Sounds like you need to lower the Pump a little. That should fix it for a while anyhow.

bob...

Click to expand...

Well, that is something I have been thinking would be worth a try.

But, before I jump in and do it, is there anything else which could cause what I am experiencing. In my mind, the spitting and sputtering is an indication of air and the only way air can get into the line is if the pump is not in full contact with water at all times .............true???

If there is any other factor which will create this type problem, please let me know so that I can check it out first.

As an update, with the pump running 3 hours today the pressure is fluctuating between 30 and 32 psi. It is not real bad as of yet and only barely spitting and sputtering on a somewhat infrequent occasion.

Thanks again!

Your Well is at the verge of keeping up, but not quite. It could be just the water level has dropped, the screen may be plugging a little or both, but the way it's acting now should be remedied by lowering it say 20 more feet. You will have to splice on some more sub cable add a length of pipe and that should be about it.

bob...

speedbump said:

the screen may be plugging a little or both

bob...

Click to expand...

Thanks for the very quick reply Bob!

When you refer to screen, do you mean the screen on the pump OR the tiny slots which are found on the PVC pipe (I assume this is considered a screen also)

And lastly, my well is 145 feet deep. The best I can remember, the pump is hanging only 11 feet from the bottom. How far down can I go safely. I would not think the pump should sit directly on the bottom, but how far from the bottom????

Notes:
1- This is a sand well fully encased with 4 inch PVC pipe. I believe the bottom two 20 foot sections were the screen (??). If the slots do get clogged, can they be backwashed?
2- Although I haven't checked this in several years, the water level used to be 111 feet from the top of the well. I have never experienced a water level higher than this, but it has done a great job for the past 30 years.

I have never seen (not that it means anything) a Well with that much screen. It could be though. Nu-Tablets might help in this case, it the screen is plugged.

I'm not sure just how close you want to get to the bottom not knowing what kind of well this is.

bob...

speedbump said:

I have never seen (not that it means anything) a Well with that much screen. It could be though. Nu-Tablets might help in this case, it the screen is plugged.

I'm not sure just how close you want to get to the bottom not knowing what kind of well this is.

bob...

Click to expand...

Thanks again Bob!

Nu-tablets - exactly what are these? Where do you purchase the tablets and do they really work to free a clogged screen (if that is what I have).

By the way, I am not sure why either, but I was there when the well driller sunk the PVC pipe and witnessed two 20 foot sections of screen being attached. The year was 1978. It has been a good well.

OK, I have done a little research and now know what Nu-tablets are and where I can purchase them.

First, I'm planning to pull the pump this weekend and make arrangements to drop it a few feet. I would assume the optimum time to treat the well with Nu-Tablets is while the pump and piping is removed ......... correct??

And last, from the information I have read, it appears Nu-Tablets are used primarily for well points. I am assuming well points are generally made form some type metal. My well casing screen is PVC. Can the Nu-Tablets harm PVC piping???

Thanks again ........... this and all of the other information should get me running or at least better understand the root cause of what is occurring.

I don't think the tabs can hurt PVC. Remember that you must keep fresh water running all the time your trying to clean the screens, this helps dissolve the tablets and keeps the solution pushing out into the encrustation that is around the screens. If the well fills up, you can be sure it's a plugged screen, if you can't fill it up with a garden hose running full blast, it's not terribly plugged yet, but may still need treating.

bob...