Brunner drill for deep drainage holes

Hello,

I am looking for a well auger to make deep drainage holes in our garden.

We have a waterlogging problem and a clay soil, the clay layer is about 2m deep, so we need to drill a bit deeper than 2m into the ground.

What kind of auger would you recommend? Should it be operated by hand or with an SDS drill?

What diameter should we use for the drainage holes? I want to fill the holes with sand initially.

I was thinking of about a 40mm auger and prefer to make many small holes instead of a few larger ones, or should I take 60mm?

2 m is quite a distance... how many holes are supposed to be made?

If you want to do it yourself, I recommend an Edelman drill. That might be possible without wearing yourself out. But it’s still quite a task... Don’t even try with a power drill. Whether that solves your moisture problem is, of course, another question... I have no experience with that.

I just want to make a few holes, about 2-4

There will be as many holes until the drainage effect shows and the waterlogging is gone

We only have waterlogging on about 1/4 of the lawn area

We want to break through the clay layer so that there is no longer a barrier that no longer lets water through

We want to completely fill these holes with sand so that the clay layer is further loosened through this

Why a Edelman auger? Why not a soil or well auger? Both are available with manual operation and with SDS drill attachment

We generally have very clayey and stony soil I don’t mind if it gets very exhausting but I have to get rid of the waterlogging my lawn is starting to rot slowly

Do you have a geotechnical report? It's possible that groundwater is already present beneath the clay layer, which would mean you have even more moisture. In some areas, it can already be at a depth of 2 mm, but someone should have mentioned this during the foundation work... In that case, I wouldn't use sand but gravel or crushed stone (2-5 mm). That way, it really acts like a drainage. Sand should then only be used for the top 20-40 cm, so the lawn doesn't dry out there...

No, we do not have a soil survey report and we will not receive one from the developer.

We only have the information that there is an approximately 2m thick clay layer beneath the clay soil.

Then I would by no means just blindly drill four holes deeper than 2m. You can generally make inquiries about groundwater levels at the (lower?) water authority; if it is around 5m or so, you are probably safe.