Hi Fellow Pond Lovers,
My wife and I bought a new place last summer, with a 1/4 acre, 8+ foot deep pond. The pond was certainly a large attraction in our decision to buy the place. The earthen dam had breached three or four years before, and the old owners did not fix it, so water continued to flow out the breach, taking more and more material away, leaving the pond level about 3' lower than normal.
We hired someone to fix it, who took approximately 100 tons of clay up the slope and filled in the void in the dam. As he did so, water continued to trickle through the clay at the repair site. He cautioned me to let it sit through one freeze-thaw cycle before adding any water, and then to add only about 6" per month, so that the new clay could saturate with water as the water level increased.
In late April I had someone fill in more of the overflow (which he had dug down to lower the pond level) raising the pond level 10". With the increase in depth, and therefore hydrostatic pressure, the trickle became more pronounced, but stayed pretty steady. In late May, I added about 6" more to the bottom of the overflow. With this increase in water level, the trickle became a flow, and in the last week or so, the flow began getting stronger.
Two days ago, I noticed it was getting alarmingly strong, and sought and found where it was coming from on the inside of the pond. About 10" below the surface, there was a 3" diameter hole, sucking water down at a steady rate. I put a large rock over it, and the flow started up again over to one side. I put down plastic and rocks, just to try to stop up the hole, which seemed to slow it down a lot- until this morning, when my wife came in to say that there was a huge amount of water going into a spot next to my temporary patch.
I stuck a 6" diameter pipe in that hole, so the syphoning action would suck air instead of water, packed clay around it, and then quickly dug out the overflow, lowering the water level below that spot.
Question: What now?? The clay in the patch was packed in by the guy driving his tractor over it. I don't believe that he did anything to key it into the old dam. Is there any possibility of doing a patch on the inside of the dam with Bentonite, extending below the old breach in the dam? Do we need to dig up the patch and do a better job of keying it in, or packing it down? Can anyone give me advice on what type of Bentonite product to use, and available suppliers? I live in Cortland, NY. I would also welcome referrals to contractors familiar with earthen pond repair.
Thanks, Swimmer
