home improvement/ old well on property ??

So you seal it up so that surface water can't get to the ground water but you want the sides unsealed so the surface water can move down to the ground water ?

 

Did you click the link I had put in my first post?

There is an illustartion that shows you layer the sand and the bentonite, no more than 10ft of sand, and thats if it's a deep dug well.

If it's only a 30ft dug well you'd most likely do 4-5ft of sand with layers of bentonite.

So, if your surface water found its way into the well casing, it's only going to travel down through the sand for 4-5ft, then hit bentonite, and find its way either back outside the casing to more filtering media, or just sit there inside the casing on the clay.

 

But there is no casing in a cistern or in a hand dug well , correct ?

I've seen bentonite used to seal casing to stone at the top just wondered how it would work in an unlined / uncased situation

 

The objective is to prevent a direct conduit, or a "bridge", between the surface water and groundwater, and instead force it to follow a better path that allows it to be purified as well as not disrupt natural lateral groundwater movement. There are other ways to abandon a well/cistern to meet this objective too, but the recommendation is usually to pull the casing if practical. If youre interested you can follow the links i provided or that gooch provided above.

 

I read Gooch's link but it only shows how to do it , I was asking what the reasoning behind the sand and bentonite layers was , which you have both answered

 

gotcha,

you're short answers can be read in a skeptical smartass dickhead way. My appologies if they weren't intended that way....eff you if they were

Bentonite is expensive, and dug wells would use a lot of it so that was the start of the reasoning for the sand. When you close a typical 4" well you use just the bentonite.

I'm not a well driller, not even close. But I do Environmental Education for farmers and often have to sell to them the importance of closing a well correctly as opposed to filling in the pit and putting a slab over the top.

 

We had issues on a 6" drilled well on one of my jobs , surface water was getting in below the 20' steel casing , we had to do a " shale trap " grouting to stop the water infiltration .

This technique is meant to seal the fissures in the rock and not allow for passage of water , that's why I asked

FU Red Wings

 

A well today is only about a 6" hole but there is a reason they make dry wells, drainage and septic rings from a monolithic concrete pour, they last better over time. Older drainage, septic and cisterns have mortar between the bricks which erode over time and the whole structure could collapse. I'm not the most safety mided but if I had a kid I"d fill it in. If it collapse's won't matter if theres a new conc cover on top.......just my .02

 

water was going down the outside of the casing to the bottom?

here they pump clay down as they drill and it pushes up the outside of the casing to help seal it.

 

The casing is only for the top 20' , there were fractures that came from the surface to below the casing , they were the result of blasting after the well was originally drilled though

 

If sealing off the aquifer was successful, that's really impressive.

I used to work for the Health Department writing permits for well construction and abandonment, among other things. In a case like that we would have suggested that the property owner drill another well. But I didn't work in a region where bedrock was present, it was coastal plain with layers of clay, loam, and sand more than a thousand feet tdeep.

 

Sucessful yes , the company that did the procedure has done hundreds , everything is on rock here

http://www.drillwell.com/

 

Rock wells.....we're in all glacial till here...

My father in laws well is 303ft, all sand and gravel. Most wells in my area are 68ft-100ft of casing, 2-15 of screen.