looking to install a new pond, approx 40'x25' for swimming. I will be running a natural filter at one end and pumping the water to a waterfall at the front. I'm getting some help from some local guys and they pretty confident I dont need a liner and the clay will be fine and water coming down the mountain will be fine.
We are in the NE mountains in a valley I've included a small topo map for context
We dug 3 test holes.
First test hole is 10' above the pond site and the hole we dugout leaks water when the water table is high, I was thinking this may be the top of the water fall and we can pump water to this basin and have it come down but it may need a liner as it drains quite quickly but you can see its mostly rubble and some clay.
Second hole is pretty much a lot of clay and my friend said this was a good sign and this should hold water well. we did get some water seeping out but it was just a pocket of water becasue it stopped a day later, we were hoping it was a spring.
Third hole was full of water when we dug it, my friend said this is also a good sign as there was an underground pond. The top was fill (and garbage) from the original construction of the property and then at the bottom appears to be clay. There is still water sitting there a few days later.
Lastly here is a pic of the front to back, the third hole in the foreground, second hole by the ladder, and the hole up the hill behind the pine.
I'm open to any suggestions or questions you might have. What is becoming clear is that we are going to have to dig more before we decide to do clay or liner, but I'd rater do clay for cost reasons.
I wouldn't want the clay exposed in the water though, I'd like to put rocks to make it look a bit more natural and prevent the clay from getting kicked up. Has anyone used any kind of concrete or mortar as a liner to keep the clay from releasing debris? is that even a concern? I'v seen a few episodes of the Pool master and thats the feel I'd like to go for.