Any serious con's to using over sized drop pipe?

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rob2290

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Hello there. New here, I am looking for advice on submersible well pump drop pipe sizing.

I have a old well on the ranch (was used for irrigation years ago, no home use, we have a separate well for house) and we are replacing the dead pump.

Some specs: The well is a 6" case, about 170ft deep with water at the 60ft - static level. The old pump was a 5-hp pentair unit installed at 120ft depth. We only need this well for the occasional use at the shop/garage located near it (no heavy use, just light occasional use... washing hands / parts, and one toilet located in shop, etc.)

The well is old, probably drilled over 50 years ago. Last use is over 1.5yrs ago and sediment was a issue with the old pump (possibly too powerful).

We opted to buy a red lion 1/2 hp 12-gpm submersible for our light occasional water needs. We also bought a Lakos SUB-12-5-K SUB-K filter to possibly help pump last with the sediment in this well. We are just looking to get a couple years of light use out of this well, drilling a new well is out of the question / expensive for our needs and our house well is way too far away to tie into. This old well is still producing plenty water, albeit with sediment.

My question... are there any serious downsides to using the old 2" 200-psi rated pvc drop pipe which was used with the 5-hp pump and use a reducer at the new pump with a 1-1/4 npt discharge.
Or do we need to also purchase new 1" 160psi polyethylene pipe? looking to save money if possible and reuse what we have. Pump will be dropped to 100-ft.

Thanks,
Rob
 

Reach4

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Using the old 2 inch PVC drop pipe to a reducer at the pump is good.
 

Reach4

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If you have not made the pump swap yet, you could run the old big pump for a while to suck up some sediment that you then put on the ground.
 

rob2290

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That is a great idea...
however, the old pump has since been pulled out. Pump was blowing fuses, after pulling it out last week and inspecting, I realized it was due to a completely blocked 2nd check valve that was installed at around the static water level mark (is this standard practice to have a second check valve for a less than 120ft drop?). I'm sure this is what caused the pump to keep overloading and blowing fuses. Big pump might still work...and was blowing fuses due to this valve blockage... visually looks fine but I do need to test it.

I am hoping the new 1/2 hp pump, lakos filter and placing pump slightly higher at 100ft vs 120ft will allow us to get some light use at the shop for a couple years.

If the old 5-hp motor checks out, I may just drop it back in to try and clean some sediment as suggested and then replace with new 1/2-hp pump to keep sediment turbulence down. Not too much work involved and I have a crane lift on hand, so great idea.

Much appreciated Reach!!

Thanks.
 

Valveman

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If the 2" pipe is threaded it will work ok. I would not use 200 class PVC in a well as it is not threaded. Since you have a crane the extra weight of the 2" pipe won't be a problem. But if any sediment gets past the SubK it will not make it to the surface. With a 1/2HP pump the velocity in 2" drop pipe is not fast enough to lift out the sediment. It will just settle on top of the check valve and cause problems. More than one check valve in a pump system is a bad idea. If the well didn't make sediment the 2" pipe would not be a problem.
 

wtahelptech

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If you have an air compressor that can produce about 20 cfm at 50 psi and hose to reach you might want to try to airlift the majority of the sediment out of that well. Might still have many years left in it if the screen hasn't completly let go.
It's easy but a wet and little dirty job but if you have the space to just let the sediment flow out on the ground - effective.

This is the primary way we "redevelop" environmental remeadiation wells. We have to contain and drum up for testing and disposal everything we bring up so it is a nasty process for us. For an old uncontaminated water well IF you have the time and don't mind getting diryt/muddy it will do the job.
 
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