DIY Water Well Questions

[Super_Dork]

I live in the Houston area and we have ground water with a head around 20' or so. My buddy and I have been working to drill our own wells and I have been finding some good help on this forum so I wanted to post a few questions here before I get everything finished up on it. First, some details:

We hand augured a 6" hole down 15' and put in a 6" thin well PVC pipe as our outer casing. Then we water jetted a 4" pipe down 40'. We removed the 4" and installed 20' of 4" .010 PVC well screen and 4" casing down to 40". The water head is around 23' at the moment. After installing the screen, we put a 2" pipe down to the bottom and used a trash/mud pump to flush the well clear. I am installing a 1/2 hp submersible pump with a 1" ploy pipe riser. It will be hooked to a 20 gal diaphragm tank. I will be hooking the tank to my irrigation system and also pulling a 3/4" hose bib off of the tank for a water hose. We will not be hooking up to the house. This will strictly be for irrigation, which is why 40' was deep enough.

For washing the 4" screen in, we used a 4"x2" reducer bushing with 2" pipe threaded in hooked to the mud pump. When complete, we unscrewed the 2" and pulled it out. Then we poured a small amount of gravel down to semi-seal the hole.

I've killed 2 pumps at this point. After installing each one, I have been able to run for as long as I like - 20-50 gallons at 10 gallons/minute. Initially, the water has been dirty and sandy then clears up around the 5 gallon mark. Then, I've turned the pump off and then the pump gets frozen and won't come on. I've been able to remove the pump, and manually rotate the impeller shaft to get it free, then run in a tank without issue. However, it freezes back up the next time down. Upon further inspection, it appears that the impellers may be getting chewed up since I'm seeing some white plastic shavings.

So, I have a third pump on order as well as some stainless screen to wrap the pump in to prevent larger particles from getting in. I'm just trying to figure out if I'm doing something wrong here.

Am I getting gravel in the pumps (doubt it since I haven't had it come out when manually reversing the impeller and can't hear it when shaking)?

Is it just the sand that's killing them?

Is my well screen not fine enough?


At this point, I've got a decent amount of time and money in this effort, but this is the most critical part I guess. Any advice, pointers, or even gentle criticism is welcome. I'm sure I've done some things incorrectly at this point, but I just want to get this working...

Thanks in advance!

 

[Reach4]

I have never dug a well.

Your screen may not be fine enough. compare the specified slot size with the sand size that you see.

You may be able to remove the fine sand with an air lift pump. Check Youtube videos.

 

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[Valveman]

A good well driller in your area would know how to complete and develop a well, as they are different in different areas. And a 40' well should not be that expensive. You will spend more on maintaining the pump and equipment than you would paying more for a well that doesn't make sand.

You should never turn a pump off when the water is still dirty, or it will lock down. You want to make sure you have everything ready and enough water in the well to keep the pump running continuously for as long as it takes to clean up the well. Then when it is pumping clean water, you can safely shut it off.

I don't think .010 is small enough unless it is surrounded by a layer of very very fine gravel (sand) pack. We would drill an 8" hole, set 5" casing, and gravel pack the annular space with gravel small enough to filter the sand.

The filter sack will just clog up and starve the pump for water. So instead of being destroyed by sand it will be destroyed by lack of water flow.

 

[Texas Wellman]

Actually valve man drilling here is fairly expensive. No driller will want to set at 40'. Probably need to go down to at least 100-120, wherever the water sand is.

Blow the well with air from a compressor and see if the sand will clear.

What part of Houston? I'm south toward the coast.

 

[Valveman]

Actually valve man drilling here is fairly expensive. No driller will want to set at 40'. Probably need to go down to at least 100-120, wherever the water sand is.

Blow the well with air from a compressor and see if the sand will clear.

What part of Houston? I'm south toward the coast.

Still, what is expensive compared to replacing a pump every few months from sand damage?

 

[Super_Dork]

Thanks for the insight valveman. I didn't know about turning off the pump while dirty. That's basically what I believe I've been experiencing.

As for the .010, my friend 1 street over drilled the same well about 18 years ago and has been working fine. He said he even measured his sand. I asked which screen he used and, via text message, said .010. Then the other day when I was talking to him he called it 'ten-thousandths', which I think is the same thing.

As for having a driller come, I've contacted several in the area and they have all declined. I'm in NE Houston in an area that was annexed by the City of Houston and on city water. Apparently, drillers can't get permits to drill within the city limits. Also, I haven't been able to find a driller willing to talk with me about how to do it myself either. We've checked the area subsidence district codes and can't find anything outlawing wells in general, so we feel like drilling ourselves is acceptable. I know that other folks had professional 150' wells drilled in the past, but since we got annexed, that's no longer an option.

We did add gravel around the screen after flushing the well, but I doubt it's packed the same way as a driller would do it.

 

[Reach4]

We did add gravel around the screen after flushing the well,

How large was your gravel?

What Texas Wellman suggests takes a big compressor -- over 100 CFM usually. It makes a spectacular geyser of water and sand. An air lift pump is much slower, but it takes a much smaller compressor.

 

[Super_Dork]

How large was your gravel?

What Texas Wellman suggests takes a big compressor -- over 100 CFM usually. It makes a spectacular geyser of water and sand. An air lift pump is much slower, but it takes a much smaller compressor.

It was just bags of Pea Gravel from the hardware store.

 

[Super_Dork]

As far as I can tell, we don't have any noticeable sand build up on the bottom. When I set the pump in and touch bottom, I can hear/feel it hit gravel, so I don't think I'm hitting sand on the bottom. Also, I would say that the upper layers of clay and sand were finder (and redder) than the water bearing sands. A week or 2 went by from the time we drilled the 4" hole to setting the screen (I didn't know if we were going to be successful so I was waiting to get the screen until we had a deep enough hole). the hole filled back in partially due to a 2' layer of water sands from 15'-17'. As soon as we pulled the drill pipe, the sand started back filling. So I think that , as you say, once we get the finer sand out, we should be dealing with coarser water bearing white sands. Even as I've been pumping up, the water as been red sand/clay from the upper layers.

 

[Super_Dork]

Here's a video of the well pumping - sorry for how shaky it is.

 

[Reach4]

It's a developing story!

 

[Texas Wellman]

How large was your gravel?

What Texas Wellman suggests takes a big compressor -- over 100 CFM usually. It makes a spectacular geyser of water and sand. An air lift pump is much slower, but it takes a much smaller compressor.

Actually it may be doable with a much smaller compressor since the static is so high. You can also run in a length of 2" pipe and blow out of that if it doesn't have enough air to blow the 4".

 

[Valveman]

Air lifting with a compressor will pull out the fine sand, and settle the larger sand around the .010 slots. This can make a filter that will keep out any fine sand that doesn't get blown out. Also blowing doesn't wear out your pump.

 

[Texas Wellman]

Also, you should use either .080 or .060 screen.

 

[Super_Dork]

So is airlifting better than pumping clean water down using the mud pump from the surface? We did that using 2" pipe run all the way down. As the water came up, it ran clear after a while.

Would this be a compressor that is rent or something? Haven't looked into how that would work.

 

[Super_Dork]

Also, you should use either .080 or .060 screen.

It may be too late at this point to switch out the screens. I've already gravel packed it in.

 

[Reach4]

Actually it may be doable with a much smaller compressor since the static is so high. You can also run in a length of 2" pipe and blow out of that if it doesn't have enough air to blow the 4".

Are you saying try 2 inch instead of 1 inch to carry the air from the big compressor.

So is airlifting better than pumping clean water down using the mud pump from the surface? We did that using 2" pipe run all the way down. As the water came up, it ran clear after a while.

Would this be a compressor that is rent or something? Haven't looked into how that would work.

Yes, you would rent a big towed compressor if you went that high volume fast route. Not cheap to rent. And it might have to be repeated at some point after you finish development. https://www.sunbeltrentals.com/equipment/items/868/air-compressors-90cfm-250cfm/


Did you look at air lift pumps? You might find this thread of interest: https://terrylove.com/forums/index....-borehole-supply-in-the-uk.61806/#post-460564
For that you would buy a much smaller electric compressor.
Also see https://www.youtube.com/results?search_query=air+lift+pump+well+sand

 

[Reach4]

Also, you should use either .080 or .060 screen.

How would that have been better than a 0.010 inch screen?

 

[Valveman]

.010 and .020 is what we use for monitor wells where we are only sampling the water and don't need much flow. Sometimes these small perfs can become clogged and not let much water in. But they should make a good sand screen if you can get it cleaned up and still produce enough flow.

We normally use .035 in house wells. Any bigger would let too much sand in the well in our area.

 

[Super_Dork]

I sure wish I had started asking questions here a few months ago. You guys are awesome. Thank you for the insight. I had missed the term "development" in my research on how to dig the well. I did some reading last night based on valveman's comments and I understand better the mechanics of establishing a good flow in the sands.

I got my new pump installed last night. It started out red and sandy again but cleared up but was still cloudy initially. I ran it for bout 45 mins and by the end it was very clear with no visible debris in it and the cloudiness went away. Thanks for the tip on keeping it running. I even tested stopping and restarting the pump after it had cleared and it worked!!

So I mentioned that I have a 6" casing with a 4" screen/casing inside. I had poured pea gravel then clean sand in until the annulus was full. Last night, I poured water over the 6" since I had heard gravel sliding down as I was setting the pump. Immediately, the water pumping out turned red and dirty again and I could hear the gravel moving quite a bit. I added more gravel, clean sand and water to the annulus until it wouldn't accept any more and shook the well pipe to make it settle. Eventually, it all seemed pretty solid and settled and the water cleared up nicely. So, hopefully, once I get a pad poured, the water should stay pretty clear.

I have a 1" drop pipe and was able to run with my ball valve fully open, but the well struggled to keep up. The output pulsed from strong to weak. I don't think that the pump ever ran out of water, but I don't think I'll be able to run wide open. I was able to run with the valve 3/4 of the way open or less with no problem the whole time. I'm planning to install a pressure tank and to reduce the output to 3/4" pipe so I'm hopeful that I can keep enough pressure on the lines to have good flow.

Based on what you guys have said, if I had used somewhat larger screen and used air lifting or some other powerful well development/sand/gravel packing, I could see better flow I would assume. Honestly, this is better than I was expecting already, though I had hoped to get the screen down another 10' but we just couldn't make it with our equipment.