It is my understanding that a mixture of clay and topsoil is the best. Clay has a high shrink to swell ratio. This gives it the property needed to swell up and seal, but can also crack when dried out because of the shrinkage.

So you do not have to have pure clay, just soil with a hih enough clay content to seal well.

If you have an old 5 gallon bucket, drill some holes in the bottom. Wet some of your suspect soil to where it will compact good. Compact with your fist or ax handle about 6" final depth in the bottom, running the clay up the sides just a little so a bowl forms in the bottom. Slowly fill the bowl portion with water and seen how well it holds. If you have water running out the bottom equals bad. Dry or just damp on the bottom means the compacted soil will hold water.

Last edited by snrub; 03/10/17 01:20 PM.
John

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