If you truly have good clay then don't waste your money on that other stuff. That stuff has its purposes but with having a good clay resource you have what you need already. I would suspect that it is bad construction causing the leak. Spend your money fixing it properly. I live in the Dayton area too and our soils are very heavy with clay so there should be plenty of clay available to properly fix the pond. The ess 13 will probably run you at least $5,000 plus shipping from Arizona, a sheepsfoot can be delivered to your site for about $300 or so for the day if you want to do it yourself. I would highly recommend contacting your soil and water district, they are very helpful and knowledgeable
Also, if you want to know your soil makeup go to websoilsurvey.nrcs.usda.gov This is a really powerful software tool that is free it takes a little playing around to get to know the software but once you do you can generate a soil report of your soil makeup.
Maybe this was already posted, but when the contractor built the dam did he strip off all organic material and dig a core trench under the dam to assure the right type of clay was present?If not, that could be a problem. Check the ground behind the dam and make sure it is not wet. As long as they built the dam in lifts of 1 to 2 ft, compaction shouldn't be a problem (even with track machines).If they threw a pile up with the hoe and leveled it a little with dozer then that's a problem. Bentonite is not the answer in my opinion..Even if you did try it, you would have to drain the pond and incorporate it in the soil. Good luck
Thanks for the input. I remember the excavator talking about a clay core. I wasn't around every day, so I can't say for sure what he did. I know he used existing dirt for the dam, but there was plenty of clay when he started to dig. he didn't bring anything in.
Well, snow and ice have been gone for over a week. I walked the area behind the dam this morning to see what I could see. the picture below is telling. Turned the well pump off today to see where it stabilizes...if it does. trying to get the contractor back out