Sediment problems - how deep should I place the pump?

I am having a sediment problem, probably clay(no sand) and am looking for a low cost solution/s. The sediment fills up my 10" x 4.5" filter pretty quickly. The well supplies a garage/shop, not a residence(no septic), but I may build a house there some day.

My well is about 8 years old, 221 feet deep, has 180 feet(+ drive shoe) of casing, flows 15 GPM(per the driller) and the pump is 25 feet off the bottom. The water level in the well is 110 feet below the surface of the ground.(100 feet above the pump)

The water has been run for > 24 hours continuously several times with no long term effect on the amount of sediment in the water.

I originally installed the pump 15 feet off the bottom of the well, but I raised it about 10 more feet last year to see if that would help the sediment issue. It seemed to help for a little while, but soon returned to about the same amount of sediment as before I raised it.

My pump is a Water Ace, Model R203A. It is rated as 1HP and 10 GPM. I am using 1" Poly Pipe(pump has 1 1/4" fittings) and the well is about 100 feet from my pressure tank.

Is there a good probability that raising my pump will at least help with my sediment issue?

If so, how high can I safely raise the pump?

How deep would you recommend that I install the pump?

Thanks, Joel

Doing the math, you are about 41 feet into the bedrock. Setting the pump up 25 feet off the bottom gave you 25 feet of room for sediment to build up. Since we don't know what kind of bedrock you are in and where the water is entering the well (top/bottom fed?), it's hard to say what raising the pump up to the bottom of the casing will do. Anything higher than the bottom of the casing would just stir up any build up of sediment.

If it is top fed and the sediment builds up around the pump motor, you risk burning up the pump from lack of cooling. I would raise it up so the pump is in the casing. That way, water will flow past the motor for cooling. Can't say if it would help with the turbidity though.

Do you need the full GPM of the pump? Maybe you could choke it back with a flow restrictor or with a CSV. I know on my well, the faster I pump it, the more clay I bring up. I had to clear out the well twice because the bottom filled up with sediment.

Thanks for the reply.

I think the bedrock is primarily Limestone.

I don't need the full output of the pump and that is one reason(also cheaper and easier to work with) I used 1" instead of 1 1/4" pipe. I may consider other tactics(flow restrictor, CVS, etc) if I need to, but raising the pump is cheap and fairly easy, so IF that tactic might work, I will try it first.

Would there be any detrimental effect to putting the pump up in the casing a few feet?

How did you clear out the bottom of your well when it filled up with sediment?

Joelk said:

How did you clear out the bottom of your well when it filled up with sediment?

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The first time, the driller came back and pumped a few thousand gallons down the well flushing the mud out. The second time, I couldn't get the driller to do it so I augered and washed it out with my old pump and then dropped in a new pump.

Some drillers will use a large air compressor hooked to an eductor to blow the well clean.

Drill another well. Nothing you do will be anymore than a temporary fix. If the well is producing that much sediment it is only a matter of time before it fills the well in and destroys the pump. Adding a CSV would do nothing other than waste more money chasing after a problem that can not be solved. Been there, done that too many times in the past ALWAYS with the same results. Well will be ok for a few months or years and then back to the same old thing.

Tom Sawyer said:

Adding a CSV would do nothing other than waste more money...

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If the sediment is only stirred up at higher GPM draw, depending on the size of tank, the CSV would throttle back the draw to more closely match the rate of consumption. Of course, you could save a few dollars and just choke back the pump with a ballvalve but that won't match the demand and won't give you constant pressure.

If I were to let my new pump run flat out, it would stir up the sediment and there is no way that I will spend $10,000 to drill a new well.

Yes but if the sediment is coming into the well it's only a matter of time before it's up to the pump inlet screen. A CSV may help for a short time but sooner or later the well will need to either be pumped out or drill another.

I can pump my well 24/7 at a slower rate and not pull any sediment into the well. It's just at higher GPM rates that I have issues. Last Summer I managed to develop the well to the point I can pull a lot more GPMs than before but I still would not run my pump wide open.

Thanks for the reply, BUT I won't be drilling a new well unless and until this one stops supplying useable water. Filters are a lot cheaper than a new well.

It may be that drilling a new well is the only total solution, and it may only be a matter of time, but that may be years, or decades. How do I know the new well would not have the same issue.

For 7 years, the pump was 15 feet off the bottom and the water always(sometimes worse than others) had about the same amount of silt in it, but never had any issues with water delivery. Raising the pump up 10' had no apparent effect on the amount of silt, but I have no reason to think the well is going to stop producing water any time soon.

The pump looked good and the intake filters were not clogged when I pulled it a year ago, so I also have no reason to think the pump will not contine to keep working fine for a long time to come.

I am looking for COST EFFECTIVE way/s to reduce the amount of sediment in my water.

I think that lifting the pump up so that it is about 10' into the casing(6" casing and 4" pump) MIGHT reduce turbulence in the water in the uncased portion of the well, and result in less silt being pumped up. Anyone agree, or disagree?

Any reason to think this would cause any problems, other than potentially causing the silt to fill the bottom of the well quicker?

It is hard for us to qualify and quantify the nature and amount of silt/sediment based solely on your description. When you lifted the pump, did you probe the well to see if you lost any depth? There is a good chance that the silt is entering from above the pump and that raising the pump may help to separate and settle out some of it. At least if there is so much silt that the bottom fills up around the motor where it sits now, you will be kinder to it by raising it. I would set it 4 feet up from the bottom of the casing.

LLigetfa, thanks for the replies!

When I pulled the pump last year, I did not measure the depth of the well, just the water level, but since raising the pump 10' had no significant effect, I doubt that it had filled with sediment to anywhere near 15'.

I had planned to just lift the pump the amount that I need to, but I may pull it all the way out and do some additional measuring before I reposition the pump.

Put a sock on the pump, raise the pump, install a backwashed sediment filter at the house but mark my words, in 10 to 15 years you will be drilling a new well.