I am building a home in upstate SC, and among other things, I would like a small pond. I need fill dirt for construction, so I told the contractor to dig a hole rather than truck in dirt.

The pond will probably end up 30-40' across, and 4' deep. It will really just be a garden pond. Our soil is typical red clay. The good news is that it perked well for a septic system. The bad news is the same- the soil drains pretty well for clay. The existing hole is about 2' deep, and when filled up from rain, it drains out in about 2 weeks. I need to figure out my best bet for getting it to hold water. The only fill source is rain, as we are on top of a ridge.

How can I test my existing clay to see if compacting it would help? From there, would I be better off with bentonite, or a liner? If I go liner, I will make the pond smaller and deeper to keep the size of the liner within reason. Thanks for your help!