Cam1210

Thanks for that…yes, he had a rubber liner in the pond that I removed to reveal the sides and base.

I'm filling in an old Koi pond. It was constructed by the previous owner of my house. He dug about a 1.5 metre deep hole and lined the bottom with concrete. Prior to backfilling it, I thought I'd better break the conrete bottom up to make sure I don't end up with an area of the garden susceptible to water logging. I used an SDS Plus drill to dig into the base and found that he used a lot of concrete! The base is about 1 foot thick. Underneath the base the soil seems wet and clay-like. After a day or so, the hole I made has filled with water from underneath and we've had no rain. We live reasonably close to a brook (within 200m) - is it likely I've reached the water table? My thinking now is, if I continue to break up the base by hiring a concrete breaker, is this a pointless exercise? Am I best just to fill the hole with hardcore in the expectation that any water will drain sideways into the surrounding ground? I attach images - you'll see the sides are dry, ground level is approximately the level of the first sleeper which sits above a lintel of concrete, then the hole is about 90cm below surface level. Pond and surrounds: Inside of the pond/profile of sides. The hole I broke through the base is just above the centre drain pipe of the pond: Close up of the hole in the base, with water that has come upwards: