How much bentonite do you need? And, how much does it cost?
My just completed pond excavation has a portion of the bottom which is suspiciously sandy. The clayey sand has less clay than I expected, and I believe my dozer operator went a little deeper than he should have, leaving me with only about one foot of the clayey sand (or sandy clay, I didn't have it analyzed) above what I know is coarse gravelly sand. We had a shower over the weekend, and the clay lined portions are holding water "on top" in shallow puddles, while this sandier material is saturated, but not holding the water "on top". I fear that it may be too porous to hold water.
Therefore, I started thinking about bentonite. This is on the flat bottom of the tank. The sides have been lined with clay, seemingly adequately. Now, I don't know for sure...it might hold, or some of the clay from the sides may wash down into the flat bottom, and seal it off.
But, if I were to consider bentonite, for a clayey sand bottom, of say 50x50 feet, how thick and at what cost am I looking at?
Oh, and the obvious answer is to get the contractor back out, but I had to wait for him for 9 months last time, and I'm not willing to entertain that again. Also, I'll probably wait to know for sure before I do anything at all, and at the rate of rain we've been having, it may be 2007.
