Battling sand in shallow well

[jd87n]

Hello,

I just dug a 21 foot well with a hand augur getting inspiration from some videos off you tube.

I dug around 21 deep total and hit water around around the 8 foot mark in pretty much 100% sand soil.

I copied some of the videos and used a 4 inch casement pipe and took an angle grinder to cut 10 foot well screen in that casing. In that casing I have 1 1/4 inch suction pipe with a check valve.

I then took pea gravel and filled the two inch gap between the 4 inch pipe and the sand/dirt and covers the entire 10 foot casement screen.

I thought I was going to be golden by having the pea gravel filter out the sand. However, I don't know what happened. I can't get the well to stop pumping sandy water. Ill pump sand comes and the next day after a recharge its even sandier. I assume the angle grinder cuts were to large and the pea gravel didn't have enough room (2 inches) around the casement pipe to do anything. When new water comes into the casement pipe its pushing in sand.


Now, I'm stuck and looking for some ideas.

What do you guys thing about me sliding down a sand point inside the 4 inch casement pipe? My thought is that if a sand point can have direct contact with sand it should be more then able to filter out the sand that is seeping through pea gravel and the screen cuts I made in the 4 inch casement with the angle grinder.

I have thought about the rusco sediment traps but I think they may fill up too often. (Plus I dont like how my suction line is 1 1/4 to the pump and these sediment traps are 1 or 1.5. (I dont know what's the better to choose and would love to have a matching 1 1/4 trap.

For what it's worth, this is for irrigation and I don't want to kill my pump or heads.

If anyone has an idea or can confirm my sand point idea id love to hear it. Also i have heard of a storage tank but I cant imaging how that would work as you would blow up the pump that gets the water to the storage tank.

Thanks, love the board. Im glad I found it.

 

[Valveman]

Pea gravel is way too big to shut off the sand. Cutting slots with a hand grinder won't work either. You need perforated casing with .020 slots and packed with silica sand just larger than .020. But a sand point will help if the water doesn't get too deep for a jet pump.

 

[Sponsor]

 

[Reach4]

He has a 4 inch pipe. Maybe put a 20 ft long 3 inch slotted liner into that?

 

[jd87n]

Thank you all very much.

This is all very new to me. For this well I may stick a sand point in the 4 inch casing and be done if you guys think that would do it. However, do I need to pay attention to the size of the cuts on the sand point also? I only see one online.
http://www.simmonsmfg.com/index.php/our-products/well-points/drive-well-point/

For the next well I dig can you tell me what you mean by perforated casement. Does that mean tiny holes instead of slits? Is there a tool that I could use to make .20 cut on a 4 inch casing PVC pipe? Or where does a residential guy like me buy a well screen that has .20

Sorry for all the questions, but finally why .20? When looking at this pic I see smaller. Any reason not to go smaller to make sure no sand gets in? Or would that take forever to fill the casing up?

Thanks

 

[WorthFlorida]

https://www.homedepot.com/p/Water-Source-1-1-4-in-x-36-in-Well-Point-WP3680/203449589

 

[jd87n]

https://www.homedepot.com/p/Water-Source-1-1-4-in-x-36-in-Well-Point-WP3680/203449589

Thank you very much. This home depot link appears to be a 80 mesh well point which if i understand equals .008 If the below pic is universal.

I just ran into someone who lives in the same area as me who uses a .10 mesh and has a sand problem. However they are unsure if they used silica sand verse some other sand around the annual area of the casement pipe.

Since my threads are full of question and are all over the place I'll condense them it here if anyone has any input. Maybe it would help someone in the future as well as me.

1. Do I need to look at the Sand-point for mesh/slot size? = Yes, you do and hopefully the below graph picture I uploaded is universal and will help.

2. Where can a consumer purchase a metal or PVC casements pipe with slot/mesh equivalents off .20 and below = Johnson Screens or Jet Wells

3. Where can a consumer purchase a metal screen of .20 and below to wrap around or inside of casement pipe = Johnson Screens or Jet Wells

4. Are there tools out there that a consumer can use to cut into PVC to make a well screen/casement from .20 all the way down to .006 = No

5. Does the lower the Slot/Mesh size restrict flow and recharge of the casement pipe. Does going to .006 restrict water water-flow. Or other words, one must balance the sediment size with the slot size to not block water flow = Yes its a balance.

6. Is there something special with silica sand that blocks other sand from coming in? Any other substrates work well also to block sand = ?

7. How much silica sand is needed around the casement pipe to be effective? = 1-2 inches

8. When buying sand to be slightly bigger then you slot/mesh size should you go one step up or more? For example on the below graph if your slot size is .20 you go to .30 sand size =?

For what it's worth I'm going to purchase a digital caliper and try to measure a bunch of sand flakes if possible to find the average sand particle size.

Thanks again to all, you are a great help.

 

[WorthFlorida]

I read that it is for irrigation in your first post. I retracted my question with edit.

 

[Valveman]

There is always a trade off. No gravel and large slots will let in the most water, but with lots of sand. Small slots and small gravel will filter out the sand, but also reduces the inflow to the well. There is a science to all of this. Most drillers will send in a sample of the sand, get back a recommended slot size and gravel pack size. 1"-2" thick gravel is usually enough, as long as it gets all the way around the casing. The slots should be slightly smaller than the gravel pack. The gravel should be slightly larger than the sand. The sand will settle in the gravel and make a media filter, which will keep out most if not all of the sand. Shouldn't be a problem using small slots and small sand for a well that uses a small pump.

No you can't cut .020 slots yourself. May have to purchase from a driller who can buy from a local supply house.

Same with a sand point. The screen size should be small enough to hold back the sand, but the smaller the screen size the more restriction.

 

[jd87n]

There is always a trade off. No gravel and large slots will let in the most water, but with lots of sand. Small slots and small gravel will filter out the sand, but also reduces the inflow to the well. There is a science to all of this. Most drillers will send in a sample of the sand, get back a recommended slot size and gravel pack size. 1"-2" thick gravel is usually enough, as long as it gets all the way around the casing. The slots should be slightly smaller than the gravel pack. The gravel should be slightly larger than the sand. The sand will settle in the gravel and make a media filter, which will keep out most if not all of the sand. Shouldn't be a problem using small slots and small sand for a well that uses a small pump.

No you can't cut .020 slots yourself. May have to purchase from a driller who can buy from a local supply house.

Same with a sand point. The screen size should be small enough to hold back the sand, but the smaller the screen size the more restriction.

Im sorry, you said silica sand above and then down here sand and gravel. To clarify, Do you mix gravel and the silica sand together (at the various sizes) to create the media filter. Then you dump that sand/gravel mix around the casement pipe/screen?

Thanks again for your responces.

 

[Valveman]

No you don't mix it. We use anything from powder fine sand to pea gravel depending on the well. The cuttings or material from the well are analyzed, then the gravel or sand is matched to the material size, and the casing slots are then sized to keep the gravel pack out of the well.

 

[jd87n]

No you don't mix it. We use anything from powder fine sand to pea gravel depending on the well. The cuttings or material from the well are analyzed, then the gravel or sand is matched to the material size, and the casing slots are then sized to keep the gravel pack out of the well.

Perfect, thank you. You mind sharing that company that tells you the material size? Id love to send a sample instead of trying to measure myself.

 

[Valveman]

Unless it was a municipal job I did it myself. When you work in the same area most of the time you figure out what works and what doesn't. I don't remember any of the companies that check that stuff other than like Johnson Screens or somebody that makes casing. Jet Stream makes the perforated PVC. They can probably give you a company name, some place you can just send a sample.

 

[Boycedrilling]

This is the sieve set I use

http://www.forestry-suppliers.com/product_pages/products.php?mi=31791&itemnum=53691