Pond liner

The last lot of (biblical) rain did for the pond liner.  It got pushed right up by water either pouring down the bank above, or a spring between 2 layers of clay.  The pond was well lined in clay, with the slightest trickle coming in from the west side.
As a stop gap, we've dug down around 350mm on the east side and put in a drainage channel.  This was a 80mm tubes placed in a small bed of gravel up against the liner, then back filled with soil.

10/8 2 months rain in an our today, pushing the liner out again.  Water did flow out of the new drain, but not quickly enough.  The only place water seemed to be getting in was the top left corner, so we've dug in some liner at that point to divert water straight into the pond, rather than trying to get behind the liner.
We syphoned the water from beneath the liner into an old bath, then put it back it.  A further 300l pumped in had the level back up to almost normal.