Earthworks/basement construction in high groundwater areas – any experiences?

When should the pumping begin?

Originally, the plan was to start the day after tomorrow (22.03.); excavation then beginning next week; directly afterwards basement construction from 03.04..

New plan: start pumping on 27.03. -> basement construction start 09.04.

I have looked at your table again. I noticed that it only deals with data of shallow depth. Do you have the chapter [Grundwasserabsenkung] or [Bauwasserhaltung] explicitly in the soil report? I could hardly make use of the data from the table in the end.

Attached are a few screenshots :) That should provide more context.

Finally usable information! So you have soil class GU, we had that too, that's good. So I would neglect settlement damage to neighboring buildings for now. Strongly sandy soils tend to shrink when water is withdrawn; as an example, look at the surface of dried-up lakes, a shrinkage landscape remains. When (fine) gravel dries out, that does not happen. 30l/s is already quite a lot. That is equivalent to 2,592,000 liters per 24 hours. We did not even pump a third of that amount.

But we also did not reach the amount I calculated but were below it. This is simply due to the calculation formula behind this number. It assumes a linear inflow into the excavation pit. However, since a drawdown cone forms around the pumping shaft, this amount of water noticeably decreases day by day. With the knowledge today, I would estimate about half for this. Initially, you will even pump more than 30l/s. On day 7, for example, it is then "only" 18l/s and ten days later maybe only 10l/s. The pumps ran 24/7 for the first three days and afterwards they shut off more and more often. Sometimes up to 30 minutes. Then pumped again for 5 minutes and so on.

This is what one of the two pumping shafts looked like at our place. These are concrete rings with holes. The rings had a diameter of 100 cm.