I had a one acre pond built 2 years ago. It has leaked since it was constructed and never filled up. During the first winter it filled to 4 feet and then we noticed water leaking under the center of the dam. The contractor discovered that he had left a field drainage tile under the dam. He patched and compacted the dam on the back side. Last winter- same thing. We would get 3 or 4 feet in the pond and it would all drain out over the next 2 or 3 weeks. After it completely drained this summer, he opened up the center front with a backhoe and discovered two clay tiles both full of water. These were dissected and the hole in the front of the dam was mechanically packed (we added some bentonite to the repaired area). I was optomistic and the latest storms here filled the pond up to within 3 feet of the drain. It is designed to be 10 feet deep at the dam. Today the ground is frozen and frosty here. and it is easy to see that there is still water leaking at the base of the center of the dam. I am a patient man, but at this point, I am losing confidence in my builder and think that he may have built us a faulty dam. He is suggesting that the pond bottom may be leaking due to the increased pressure of the water and that water is being forced under the keyway and up at the base of the dam in the center. We have had record rains here during the first two weeks of January and the ground is saturated. His explanation does not appear to hold water to me. Pun intended! I may be at a point where I need an expert on my side to find out what is going on and who should be responsible for fixing it....Any suggestions?

My question is did he layer the soil in 6 inch layers when packing the keyway and dam and if he did how could he have missed the clay tiles?

In my opinion, anyone who "misses" a drainage tile UNDER the dam, then tries to correct the problem on the "backside" of the dam should be tossed out like yesterday's garbage. You are spending hard earned dollars for a pond of your dreams, get another person. It's unlikely you could recover damages, just chalk it up to experience. Spend some time, talk to the people in your area...most of all, QUIT talking to the guy who built your dam, he's only going to give you another headache !

Sadly I have found, at least in my area, about 7 out of 10 so called pond contracters have little knowledge of how to correctly put in a keyway or pack a dam, let alone know what you are talking about.

Longview
He did not cut a key way into the bottom of the dam , our the key way was not cut deep enough, to find the field tile.If a pond fills up to fast that is not good, most dams need time settle in.

This contractor has built many ponds in our area without problem. I didn't watch him pack the trench, but I have no reason to believe that he did not do it correctly. He seems to think that these tile were buried exceptionally deep and that the keyway went over top of them. Although I was helping when he brought the backhoe in the second time and dug in the front of the dam and found the second tile. It did not seem to be deep enough to be going under the keyway. Can this dam be repaired? Does his explanation that the bottom is not sealing and that the water we see in the middle back of the dam is being pushed down through the bottom and under the dam make any sense? I appreciate all of your ideas and comments......

The core trench or keyway, should be cut sufficiently deep to reach good clay soil into which the dam core is compacted.
I have to agree with Cecil in that if the dam builder built the dam on top of any pipe he does not know what he is doing.

This should never happen!

Good advice has been given.
I concur, find another pond builder & stop wasting time & money!

Consider exploring draining the pond and revisiting the keyway. If water leaks through the dam it's either because poor soils were used to build the dam; soils weren't properly compacted; or the keyway wasn't built properly...or any combination of these three. Start with the keyway. I suggest you call Mike Otto and consult with him. He will prove to be helpful. Beyond that, hire an engineer to evaluate the problem, then pursue the best solution. Call Otto at 800.882.DIRT

Thank you, Bob! I will give Mike a call.

What are the dimensions of the dam & key way? Was the top soil & other organic materials separated from the donor material?