Extend the drinking water transfer shaft with a bearing ring

Hello everyone,

my driveway project also includes raising the existing transfer shaft for drinking water. It is a concrete transfer shaft with climbing irons. A sturdy shaft cover is located on top. Inside the shaft, the drinking water house connection is connected to the water supply connection of the water utility. The shaft is closed at the bottom. There are already two concrete support rings on the shaft.

The desired increase is about 13 cm so that I am at the height of the upcoming driveway.

My questions:
I have seen that the two existing support rings were simply placed on the shaft. It seems that no cement mortar was applied between the levels, nor were the joints at the connections plastered with cement mortar. Is that correct? After the winter, I had 3 cm of water in the shaft. It must have entered either at the cover on top or at the points where ring meets ring. Since I have now exposed the shaft far enough to remove the two existing rings, I would add the cement mortar and also set the additional ring on top in cement mortar. With an additional 10 cm ring plus the mortar at four connection points, I should reach the 13 cm. Or would an 8 cm ring be better, since the cement mortar adds more height?
Do I need to prime the concrete parts beforehand or something like that so the cement mortar sets well and holds? Do you use ordinary cement mortar at all, or does it have to be something special?



Before I close it again with RC material in the end (I have exposed the shaft up to ring 1), I would wrap a dimpled membrane around the outside to provide even more water protection. Does that make sense?

I would use fountain foam. Spray it on once, put the ring on, and you're done. It's also somewhat waterproof. If you have gravel around it, there should be no standing water. I would use mortar if your driveway has a slope. Then mortar the ring so that it lies exactly in the paving level. Don't set the shaft horizontally and the driveway with a slope. That looks bad.

You won't get it 100% sealed because the lid just rests on it (and it is only allowed to rest on it). There should be a pump sump in the shaft anyway. So it's normal that there is water inside and you have to pump it out regularly. So dial down the panic levels by two steps. I think we currently have about 10cm standing at the bottom.

And otherwise, simply use a butyl/rubber/EPDM sealing tape from the outside, which is self-adhesive. It won't get any tighter than that (if you have already glued or mortared).