Thread: Subsidence

Need a Help here

I have top pond for plants and waterfall to a lower Koi pond its still a fair size 1m deep 4.5m dia circle but it been in several years and this summer was the worst I am on clay and the super dry summer has caused to pond to tilt. Other years it dropped a bit but this year its huge. Previously when the wet weather came the clay expanded again and it lifted back up to level but I am not so sure this year.

Has anyone ever underpinned a pond? or any other idea is welcome.

Andy

Does the pond have steel rebar?
Resin injection to lift the concrete is relatively straightforward but would need drilling for access and several slow lifts with an experienced operator to avoid over expansion.

Or you could install several overhead beams, attach threaded rod or clamps or cable and hydraulic lift back into place. Then drill some access holes and inject expanding foam under the pond to fill the voids.

Or you could use a weeper - soaker hose for a couple of weeks in hopes of re-hydrating the soil so it expands again.

Or leave the pond where it is but build up the sides with more concrete so it's level again.

Wetting the soil with a weeping soaker hose really does work, have a look at online discussion forums where they lift concrete house slabs. It's the cheapest low effort method and apart from taking time, you can always look at other ideas later if not successful.

Thanks for the advice, I suspect I am going to have to try something. Its raining a lot now so I may just wait a few months and see where we are heading.

That sounds proper stressful.

My Filter pit subsided, it was attached to the pond and detatched itself then split in the middle. The fact it detatched itself from the pond was probably a blessing as it saved the pond going down with it.


On the right is the filter pit wall, on the left is the corner of the pond:




The opposite side of the filter pit to the pond, the right half of the filter pit has sunk and the left half has started sliding down the bank at the end of my garden:




As you can clearly see from the photo, I bodged the repair by grinding into the blockwork and installing helicoils and injecting resin, then added a lightweght course of blocks to bring back to level (I needed to go up a course anyway to install the drum filter and fit hinged filter pit covers, so all the mess is well hidden:




Filter pit with pond on the left:






Had the pond itself sunk and wasn't leaking I would have levelled it in a similar, less bodgy way. Had the pond been leaking I think it would have worked out better to rebuild it from scratch.