Filling old Koi pond with 10" base reinforced concrete base?!

[leeovery]

Hi,

I have an old koi pond which was installed by the previous owners. We had it for 3 years but have now decided to get rid.

The hole has been drained (mostly) and de-fished, de-frogged and de-slimed. But the issues are only now beginning...

The plan is to fill the hole with rubble, top off with MOT1 and put a concrete reinforced lid on it so we can put a large hot-tub in that area. That part is straight forward.

The issue is getting the base broken up so that water will drain away when it finds its way down there, through the rubble etc.

The pond was created with a lot of love. It's in the ground and is 2.7m x 6m x 1.5m (deep). It has brick walls with a fibreglass liner (very tough).

At the bottom, Ive just discovered after much smashing and breaking, is at least 10" of reinforced concrete + a decent amount more inches of rubble / hardcore.

Water is coming up from the hole Ive dug at the bottom, but when I fill with a hose and leave it, its not draining away.

So... my question really comes down to...

Do I need to continue to smash up this base (which will take a long time and will probably require I upgrade my electric breaker for a hydraulic one) or...

... can I do something else to ensure water can escape from the bottom after filling with rubble and concrete etc?

To add, we plan on building a gazebo with a felt-lined roof over the hot tub, so concrete bad the tub is sitting on (which will be on the old pond hole), wont get loads of water. Bit still need to know water can escape at the very bottom.

Very sorry for the long post. Anybody that can help guide me on this will be my hero!!

Thank you
Lee

 

[r896neo]

Is it in a low area of the garden or is it on any sort of slope? If its in a depression and you live on flatish land you may have run into the water table if water is not draining away? Are you sure you have smashed or removed the bottom drain? A koi pond will obviously have been pumped so the pipework might have created a ubend of sorts stopping water from draining completely.

If you have removed the bottom drain thoroughly and its still not draining then it may be a problem.

I don't see any need to remove more of the base than a 4"hole which should be there when you smash/drill out the drain. You may need to temporarily pump it out so you can see what your doing and check its not going to partially refill itself via the water table.

 

[r896neo]

Oh and please wear a mask when cutting fibreglass.

 

[leeovery]

Thanks for the reply.

I have been wearing a mask - thanks for your concern though.

To clarify I have drained the pond. I'm now trying to create drainage on the bottom so that when I fill it with rubble etc, any water that manages to find its way through will have somewhere to go.

The pond is on level ground and isn't particularly low. But it is 1.5m in the ground. And that's to the bottom liner. I've also dug a 6-8" hole in the bottom. That's where I've found water. I suck it out of the small hole but it refills over about 5-10 mins. I suspect it is the water table.

Does that mean, after I fill the pond with rubble, any water that seeps into the "hole" will drain away?

At the moment I'm planning on hiring a pneumatic breaker and going to town on that base. Talk about over-engineered!!