Pond Boss Forums POND CONSTRUCTION Soil questions Confused about different clays.

I'm almost finished with my pond and my brother-in-law who works for the state gave my number to a guy from a large construction company that needed some clay. His boss wants to seal a pond with it. He came out collected some samples. I have a hill that I was working on removing. The top three feet is black clay topsoil. The next layer was a yellow and white marbled clay. The next layer at six feet was gravel-like fossil. Deeper than that was filled with water so no sample but it has layers of rock with dark yellow clay in between. He took another sample of sandy yellow dirt for my curiousity.
The black dirt tested 37 PI
The next layer of yellow tested 22 PI
The yellow fossil shell layer tested 27 PI
The yellow sandy stuff tested 7 PI

He wants to come get the black stuff. If the black stuff held water there would be puddles everywhere. In my experience with these soils, the black stuff doesn't hold water. My new pond along with other ponds on the property hold water great. They were made by pushing the black stuff out of the way.

All the gravel and rocky yellow stuff is what I use for my dam because it holds water and the rock and gravel keep if from moving or mushing when the heifers walk on it.

Another thing. The sandy yellow stuff that tested 7 PI I used for fill with young calves and they packed it so good that you can drop water on it and it sits on top most of the day. I would use it before I used the black soil.

Is what I call the "useless black *&4&" not useless?

Test the useless stuff by packing some of it in a 5 gallon bucket. Try about a foot. Make sure it is packed really well. After the stuff get good and saturated, drill a small hole in the bottom of the bucket and see how long it takes to leak out.

What is PI?

plasticity index

That really is a good test

its likely yer black stuff is highly fractured from shrinkage and swelling (freezing and thawing) plus root penetration from weeds and grasses etc....so water drains through it. take the same soil, dig it, grade it, crush it with a dozer, roll it w/ a sheepsfoot, and wala....beautiful clay to line a pond with.