I am not sure there is much you can do until spring. You can keep trying to pack in clay for now, but to do a good and 'guaranteed' job you may need to bring it up in the spring. You could however try pumping some water out and filling in around it better with clay/bentonite or cement. Either way you are best to cut off the pipe flush with the pond bank to remove the possibility of ice leveraging it and lifting it out again. It isn't so much of a problem in ponds that don't have an inflow, don't freeze very solid, or are close enough you could put a cattle trough de-icer or such at the opening. I believe there are others on the board that have had similar problems that may have other ideas.

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