More well pump questions

[Ook]

To continue the popular subject of wells and pumps: My current setup is a shallow well that consists of a 2" pipe driven into the ground. The water is at 10 feet, the bottom of the well is at 17 feet, giving me 7 feet of water. My pickup tube is a 1" pvc pipe with a 1" foot valve at the bottom. Right now It's only a foot or two from the bottom - too close, because it picks up sand, and I can hear it rattle through the pump. My pump is a brand new 3/4 horse Star pump, model ES07S

It is entirely possible that the capacity of this pump exceeds that of my well, but I won't know until I pump it at capacity for a bit.

I'm not sure how far down the water goes during the summer, nor do I know how far the water level drops when pumping. I seem to recall it dropping to about 5 feet or so last summer. The bottom of my pickup tube then was less then a foot from the bottom of the well, and I never ran dry. I did, however, suck a lot of sand and rocks that were small enough to make it past the screen on the foot. I popped off the front of the pump casing, and it had quite a bit of course sand in it.

I want a pickup pipe that is less restrictive then a 1" pipe with a 1" foot valve. I'm thinking of using a 1 1/4 pipe with an inline valve at the top instead of a foot valve at the bottom (I used to run this way, so don't tell me it won't work - it worked fine). I can't put a foot valve on the 1 1/4 pipe, because it's too big to fit into the well opening, a 1" foot valve is the biggest I can get in there. The only problem is that without a screen at the bottom, anything can get sucked up from the bottom.

Questions:

1) Given the above information, how far off of the bottom of the well would you suggest I put the 1 1/4 pipe, so that sand and rocks won't get sucked up the pipe? Would you consider 4 feet to be a safe distance?

2) Where can I get a screen to keep out rocks and sand and stuff? So far, all I get are blank looks when I tell people I want something to keep rocks and sand from being picked up. All I get is advice to raise the inlet higher from the bottom of the well (which I'm sure is actually good advice). We don't have sandy soil here, so sand traps may not be very common.

3) Pressure tank. I have my turn-on pressure set at about 23psi. I want the pressure in the tank to be at ~20-21 psi for max efficiency. That way the pump kicks in right before the tank empties. Otherwise, if the bladder hits the bottom of the tank, there will be a rapid loss of pressure until the pump kicks in. I'm assuming this is correct?

4) I wish I had the money to get a bigger/deeper well drilled :-). OK, so this isn't a question, it's just wishful thinking.

[Pete C.]

If it does I expect you'll get a cyclic sucking of air and repriming delay. Should be pretty obvious. Not positive, but I think you can throttle the pump back a bit with a gate valve on the output to provide an adjustable restriction.

I'd suggest that it is of little consequence if the sand is sucked up through the suction pipe as long as you prevent it from getting into the pump.

The spec says 15' suction lift so it should be fine.

Put it at the 15' level, 2' off your 17' bottom, and put make a cone of SS screen to attach to the end to keep out big stuff. Don't worry about sand.

Make a separate easily serviceable sand trap located next to the pump. Try something of moderate diameter and depth so the incoming flow slows enough for the sand to drop out.

Probably not. Shallow driven wells with jet pumps aren't common in many areas either.

Sounds ok in theory, might need a little tweaking in the real world.

Have you checked on cost? A lot of places 500'+ drilled is the norm, sounds like your area is a lot easier.

[Harry K]

Drilling for a "shallow" well isn't all that expensive. I paid somewhere around $2500 for a 6" 65' deep well. It was a 'turnkey" contract, i.e., included everything, pump, tank,drilling, trenching, wiring and pipe to the house.

Harry K

[Tim Smith]

Here's a page from a well-drilling company that has an interesting chart showing the depth and cost of all the wells they drilled in 2006:

[Harry K]

Thanks. I have that saved now. After making my $2500 post I began to wonder about my memory. That seemed way to low to me so I may be way off in what I paid. Then it was over 10 years ago so prices would have gone up considerable since.

Harry K

[Ook]

So, I found a filter. It's a fine screen in a platic case and you can unscrew it to screen it, and it's transparent so you can see if stuff accumulates. Installed at pump. Removed foot valve and screen from bottom well, installed a 15 feet long 1 1/4 pickup tube that sits about 2 feet from the bottom of the well. Installed check valve at top of pipe at ground level. Runs great, no more rocks and stuff in the pump. So far so good, it can run 3 sprinklers just fine at about a 50% duty cycle. It tends to suck a bit of air at high volumes, so I'm thinking that I might be pushing the limit of my well's capacity, it is a 2" pipe after all. I also found that it depends on what sprinklers you use, and what hose you use. A 100 foot 1/2" hose probably won't run 5 sprinklers :-)

[M Q]

If you have a marginal well (if it is sucking air now it probably is -- just wait till then end of a dry season or drought year), you may want to consider one or more of the following suggestions:

1) You have a shallow well with a (currently) relatively high water table. As another poster mentioned, the cost of drilling a deeper well may not be that much. You would need to check locally, as the cost would vary regionally and depend upon local geology. (I drilled a 320' 4" well for about $10k in 1990, mostly through shale.) 2) Get a "Pumpsaver" or similar. It will protect your pump and can also be used in conjunction with a storage tank to get the most out of a marginal well. 3) Get a storage tank and pressure pump. You can then fill the storage tank at a low flow rate (to match your well's ability), but then you will still be able to consume water at a high rate. You can then either throttle back the well pump (not the best solution), get a smaller well pump, or use the Pumpsaver to automatically shut off the well pump for a recovery period that you set.

[Ook]

I've never been entirely sure where the air is coming from. I noticed last year towards the end of summer that it would discharge a small quantity of small air bubbles - not a lot, barely enough to be noticeable. You could heart it as they spit out if you put your thumb over the end of the host to spray water. It almost looked like a leak, rather then the intake sucking air due to low water level. If I put the hose in the kid's pool, you could likewise see little air bubbles coming out. I've replaced all the parts but the coupling at the top of the well. That doesn't leak a drop, bone dry. I figure if it can hold

60psi, it shouldn't suck air when it's lifting water from 10 feet down .

PS I like the water tank idea. I wish I had one! A big one, and I wish I could fill it during the winter with all the rain that falls around here.

[Harry K]

It is probably air disolved in your ground water. Some localities have a lot, some only a bit. I will occasionally get a bit also. Nothing to worry about unless it becomes a gross amount - that would indicated pump/piping or low water problems.

Harry K

[dpb]

A leak that is air ingress has to be on the suction side, not the discharge, otherwise the pressure differential forces water out, not sucks air in...

Besides, how would you know the difference between an air bubble from that source vis a vis one from the inlet turbulence? What would "look" different?

...

The amount of dissolved gases are not likely to change grossly w/ seasons if that's the source -- late in the summer I'd wager it's much more likely marginal level.

[M Q]

The capacity of a well depends upon the static height of the water table above the pump (7 feet in your case) and the porosity of the surrounding soil/rock. When you pump, the water level in the well goes down (which is also why more water will flow into the well). When you pump at a rate that exceeds the capacity, the water level goes all the way down to the pump inlet and you suck air, and thereby reducing the pumping rate to match the well capacity. You did say: "tends to suck a bit of air at high volumes" so I assumed that that was what was happening. Do you have a way of monitoring the water level as you pump?

Also note that there may be a different short term and long term capacity. i.e. you may be able to pump 10 gpm for an hour or two, but not days or weeks.