Hello!

I am in need of help.

Last Autumn, a hole was dug by a creature in our lawn, about 9 inches or
so from our pond. The hole was about 7 inches in diameter and appeared
to have been dug by an animal standing on the lawn as the soil excavated
in the digging of the pond could clearly be seen strewn in one direction
(and some of it went in the pond). We assumed that a fox did the digging
- we sometimes see them about.

I filled it in but it soon reappeared. This happened a few times.

Then a smaller hold (about 3 inches in diameter) appeared in the same
place. The difference this time was that the hole had very clean sides
and there was no debris surrounding the entrance/exit of the hole so I
assume that it had been dug from within.

This was duly filled in and reappeared so I placed a large stone on top
and it stayed like that for several months over the winter.

About three weeks back, I took it upon myself to excavate the hole
properly and to see if there were any tunnels under the lawn. I duly
did this, and found that the hole was at least as deep as the length of
my arm and appeared to run off in at least one direction - towards the
pond (I think it must have gone as far as the pond liner)!!! It was
difficult to tell if it also ran away from the pond.

After widening the mouth of the hole, I carefully filled the entire void
(or as much as I could reach) with soil and packed it down. I then added
some lawn seed to the surface and have been watering it since.

However, 2 days ago, the 3 inch diameter (and clean hole) returned!

I filled it with soil (it went fairly deep - it needed a surprising
amount of soil) and stamped it down.
Yesterday, there was a small hole in the same place - possibly where the
soil had collapsed slightly into a remaining void beneath (as it had
been raining). Today, the hole is back as can be seen in my photo:
http://www.zen24579.zen.co.uk/Photo-0057.jpg

Now I am concerned. I wouldn't mind so much but I think that my pond is
in danger. If anything burrowing beneath should get through my pond
liner then my hard work building the pond will have gone to waste.

What could be making the hole? How can I stop it? We have looked
around for another hole (including in the nearby alleyway) but can't
find one.

Any help would be very gratefully received. Are there any forums online
which might be more appropriate or have I come to the right place
(apologies if not).

Thank you,

Kroma
Essex, UK