Ned help with another well/pump

[Qapla]

This is an irrigation well. It is a 4" well that has a 5HP submersible 3-wire pump with the controller located above ground. It has a "Well-Xtrol" bladder tank. It has 2" drop pipe feeding a 2 1/2" mainline. There is a 2" in-line filter between the well and where the tank is located. It had been working just fine producing about 35 GPM.

A couple years ago, before I was dealing with this particular system, they had a well company say the well needed to be deeper and I was told they drove the casing deeper and added drop pipe but I cannot verify this. The pump is currently at 63' according to the information they recorded inside the cover of the control box.

The system is having problems.

When I remove the bottom portion of the filter and the filter insert and turn the pump on I get full flow. After about 15-30 seconds the flow drops considerably. If left running the flow will begin to surge between full flow and the diminished flow. If I turn the pump off and back on, the flow will be full at first then the surging will resume.

Does this sound like a problem with the pump, controller, tank or the well itself?

I need to let the owner know if he may need a new well or if this one can be fixed.

 

[MillWeld]

A 2" filter sounds awfully small for a system that produces 35 gpm and would get clogged very quickly. Can you show a pic? Are you sure it is not a checkvalve?

Bob

 

[Qapla]

The inlet/outlet of the filter housing is 2" pipe thread. It is the same filter that is installed on another irrigation system at another location that also has a 5HP 4" setup and that one works just fine. If there is a check valve between the pump and the filter it is down the well. With the filter cartridge removed and the filter left open with the bottom removed (thought I said that) the water should gush out of the 4" opening of the filter housing. It does start that way, but unlike it's counterpart at the other location, this one does not keep the full flow.

 

[Egon]

check the water level in the well.

 

[Just Bill]

I am not a well expert by any means but it sounds like you are running out of water.
Either the water level has fallen, the well has filled in with sand, or something along those lines. Its also possible that the casing collapsed.
Seems you are not getting enough water into the well bore to satisfy the pump.
I would run a rope down the well to see if you still have the right depth.
You might need to use a large air compressor and jet the well to clean it out.
Good luck

 

[MillWeld]

Could the pump be cycling on and off be the cause of irratic flow? If so, is the pressure switch defective?

 

[Stimw]

You are pumping more water than the well can recover with the pump at it's current depth. The pump is running out of water, then the level recovers and you get the surge.
Do you know the total depth of the well? You might have to lower the pump if you have room.
If you got the rain from that storm we just had (over 20" here in St Johns Co.) it might start working again.

 

[Qapla]

It is quite possible that the well is running dry. That was what was thought by a well company a while back, but never really determined for sure.

I cannot drop anything down the well with the drop pipe and pump in place and have no way of pulling it out to check. The owner of the apartment complex wanted me to check after the rain we had ... so far we have had 28+" since January - we only had 23" all last year. Before the owner puts in a new well he wanted me to re-check the existing well to see if the rainfall might have cured the problem.

It may be that I will have to tell him that the new well still needs to be drilled.

 

[E/S]

Sounds like the pump is pulling more water than the well can produce.

E/S

 

[MillWeld]

I think you got intelligent answers fro Stim and E/S.

 

[tuerdon]

sure sounds like the pump is going dry, watch that, it will burn out quite quickly. Just a thought, if you have another water supply and can direct it to the pipe you might be able to run water down the pipe and see if it works OK with a extra supply of water. There must be a way to pull the pump out of the casing otherwise it's a dead end waiting to happen.

 

[Qapla]

A well/pump company could easily pull the pump ... I said I have no way of pulling the pump.

In fact, if they do put in a new well the idea is to pull this pump and put it down the new well to save some cost. I will also be the one tying the new well into the existing mainline and connecting it to power because it will be less expensive to the apartments then having the well company do it.

Thanks for all the replies. I will tell the owner today that he still needs a new well

 

[bullockcm]

I know you talked to the owner yesterday but here is some data if you need further justification. BTW, I belive the surging is the result of the well running out of water. Using the information you gave, well diameter = 4", pump at 63'. I will ask here, are you sure the well is only 4" bore, I am actually surpised a 5HP pump fits in a 4" bore well but I know things do differ greatly in different areas of the country. Anyway using the 4" and 63' I come up with 9495 in^3 of area which is best case since I doubt the well casing is ever full to the top. That area converts to 41 gals. Best case scenerio, you are pumping the water down to the pump level in slightly more than a minute. This of course ignores the well recovery rate. The fact water is still being pumped even with surging suggests the recovery rate must be quite high.

Someone mentioned it prior but the other option to drilling a new well would be to see if the pump could be lowered in the current well. Here in western NY we always kept pumps at least 3' above the bottom of the well, that may or may not be applicable in FL.

 

[Qapla]

... I will ask here, are you sure the well is only 4" bore, I am actually surprised a 5HP pump fits in a 4" bore well but I know things do differ greatly in different areas of the country....

Yes, it is a 4" well. Here is a link to Meyers Pumps - All these pumps are for 4" well and range from 1/2 - 10 HP (the actual diameter of the pump is 3 3/4" ... but they are a bit heavy and awkward to move around ... some of the specs - LENGTH: 21-3/4" to 71-5/8" WEIGHT: 23 to 98 lbs DISCHARGE: 304 Stainless Steel, 1-1/4" on 5, 10, and 16 GPM, 1-1/2" on 25 GPM, 2" on 40 & 75 GPM). I have recently installed a 1 1/2HP @ 20GPM and a 2HP @ 35GPM pump for this same owner at a couple other properties. This particular property has a 5HP pump that should do about 55GPM but the best I have ever been able to get is about 35GPM.

This well has been extended deeper once before so trying to go deeper again is not an option. In addition to the surging, it also pumps various amounts of sand into the system. The owner was planning on a new well but wanted to check and see if after all the rain we have gotten if the well may have come back. Evidently, it has not.

Since Florida has a lot of lime rock, clay and sand, there may be some differences to how a well recovers here then one in the rocky terrain of other parts of the country. Usually, well guys try and seat the casing in the lime rock (hard-pan) then bore on through to a good supply of water. For a drinking well, they try and hit a good aquifer. For irrigation, they will settle for a pocket.

Many of the shallower irrigation wells around this area of Fl are a bit on the sulfur side. It is kind of a shame that this well went bad since it was good clean water without the sulfur when it worked.

For the owner it is now an added expense he must deal with. For me, it is some additional work he will send my way when the new well is in since I will get the job of tying it into the irrigation system and connecting it to the controller.

 

[Stimw]

Here in Florida if a well is put down more than 50' you need a state licence.
We basically have two aquifers, the surface and deep. When they go down for a deep well they have to seal the casing so they don't co-mingle and or contaminate the deep aquifer.
If it is pumping sand there might be a joint in the steel casing that has rusted through. ????

 

[Qapla]

I am sure this well was put in by a State Licensed installer. It has been in for many years. I think it has just collapsed from the drought conditions over the past several years, thus the reason it needs to be abandoned and a new one put down in a different spot. The location they are planning on putting the new well is about 50'-75' from the old one.

I guess I should suggest that when the well company puts the new one in they need to supply enough wire to reach where the connections will be. I really don't want to have to splice the wire run.

 

[bullockcm]

Interesting to see the regional differences. Any idea why 4" wells are used instead of a larger diameter? Here in western NY we pretty much have clay & rock. Wells are typically 100 - 150 feet but can be as deep as 300 feet. Casings for residential and most farms are 6" with bigger farms being 8". We also spliced the wires at the top of the casing & used a pitless adapter which is saddle type fitting through the casing with an o-ring seal. Splicing the wires at the top of the casing made pulling the pumps easier which isn't uncommon due to lightening strikes.

Sounds like you have plenty of experience, good luck when it is install time.

 

[Ranger Rick]

Do you need 35 gpm or could you put in a smaller pump that would better match the flow of the well?

 

[Qapla]

... We also spliced the wires at the top of the casing & used a pitiless adapter which is saddle type fitting through the casing with an o-ring seal. Splicing the wires at the top of the casing made pulling the pumps easier which isn't uncommon due to lightening strikes...

Yes, I could just splice the wires at the top and this may be what I will have to do - I just need to either put them in a box or use water-tight splices.

As far as lightening, since Florida is sometimes called the "lightening capitol of the world" (we get more strikes then most places) this is one of the reasons that many well companies use the 3-wire systems (instead of the 2-wire) since that puts the control box with all cap actors and relays above ground and easy to replace. Lightening usually seems to take out the controller not the actual pump. However, with the 2-wire systems, the caps and such are down the well and the pump must be pulled after a hit.

As for the pitiless adapter, since we do not have the freeze worry, pitiless adapters are not common fare here. on many wells the casing extends above ground level with a well seal and the feed pipe connected to the drop pipe with a union.

Do you need 35 GPM or could you put in a smaller pump that would better match the flow of the well?

I have already revised this system to operate on the 35GPM and still cover without cycling the pump. I cannot make the zones any smaller since that would require running new wires and installing new irrigation clocks/controllers - not cost effective.

If I try to nozzle any smaller not only would I lose coverage, they only make the nozzles in certain usage amounts and I cannot change that. I need at least 35GPM on this system.

If it were a new install I would simply do a flow test and design/install the zones according to the delivery rate ... but, on an older, existing system you sometimes have to work with what there is and try to do the best you can to make it work.

 

[Egon]

Just for interest the pump capacity can be reduced by drilling holes in the diffusor's.