Water well producing sand any well experts in the house?

[Legdoc]

Happy New Year from South Texas! I have a 4" PVC cased well that is approximately 300' deep. The well was taken out of service February 2022 due to damage from the freeze. I pulled the 1hp submersible pump that was set at 100' on 1" poly pipe. My plan was to resurrect the well with a new pump as the old one was weak possibly from the impellers being chewed up by sand. So, I set-up my 185 CFM compressor with 200' feet if 1" poly pipe and a 4" jetting head. The first jetting at about half of the compressor capacity produced really smelly water with quite a bit of sand which cleared nearly completely after about 10-15 minutes. My estimate the well is producing about 75 GPM.
I have re-jetted the well 5 times over the week and each time it again produces much less sand than the first jetting and clears quickly. I have ran the compressor up to 30 minutes and would thing any sand in the casing would have been expelled. I don't understand why it clears each time and does not continuously produce sand. The well is about 25 years old and I have no idea how it was done done. I.E. open ended, improperly screened. small holes drilled in a cap... We never had a problem with sand in the house.

Hopefully someone will have some advice. I could always screen the well with a packer.

Please help!

 

[skyking1]

I am not a well expert:
When you jet the casing, the pressure forces the sand away. it is not the natural state of the well.
Take the pressure off and gravity takes over and brings the sand back in.
Have you re-set the pump back in at 100' and are getting sand, or are you just jetting it over and over and expecting the sand to go away?

 

[bam1968]

I'm no well expert but i'm having a hard time wrapping my head around the idea of a 300 ft casing and basically having sand at 100 ft (assuming the casing is in good shape). I'm not real familiar with your soils either. How deep are you getting with your 200' of jetting pipe?

 

[JLarson]

Not knowing anything about the well you should have it videoed. Could have a break/separation in the casing or you're taking in sand from the screens if it has them.

 

[cfherrman]

I know a thing or two about wells.....oil wells....

If the well is producing sand, the sand will not come in without fluid entry, so unless you are removing lots of water from the well it won't make much sand.

 

[Legdoc]

I am not a well expert:
When you jet the casing, the pressure forces the sand away. it is not the natural state of the well.
Take the pressure off and gravity takes over and brings the sand back in.
Have you re-set the pump back in at 100' and are getting sand, or are you just jetting it over and over and expecting the sand to go away?

I am jetting over and over with probably a false hope of the sand still coming up being still being remnants of the previous jetting. also hoping the formation will stabilize.

 

[Legdoc]

I'm no well expert but i'm having a hard time wrapping my head around the idea of a 300 ft casing and basically having sand at 100 ft (assuming the casing is in good shape). I'm not real familiar with your soils either. How deep are you getting with your 200' of jetting pipe?

On the first jetting there was much, much more sand produced. I don't have the well log but the two wells I dad drilled indicated mostly sand separated by clay layers. I have the full 200' of poly pipe in the well.

 

[Legdoc]

I appreciate the replies. I have talked with my well man this morning. He suggested no more jetting and pour 5 gallons of pea gravel in the well, sanitize it and install the new pump, tank and see how it does.

 

[skyking1]

That is what I would suggest. Not the pea gravel though, great call there.
If you dangle at 100 and have good water there through the dry season, you will probably not see the sand in your lifetime.
That is based on typical 5~10 GPM usage for domestic water. If you are irrigating with it hard, then all the bets are off the table.

 

[cfherrman]

Lol I read your post backwards

 

[Delmer]

Jetting is going to produce sand, that's what it does is rinse the sand out, right? The way I understand sand well development, the idea is to shock the well to rinse out as much sand as possible, then continue many times with lower and lower pressure/volumes to build a stable layer of coarse sand outside the screen, for the most flow through the screen. I would run the old pump down on 300'+ of pipe and let it run a few feet off the bottom until the sand is gone, then drop it a bit at a time till it's sitting on the bottom and let it run 24 hours there, maybe moving it up and down every couple hours at first to keep from getting locked in place.