Allthewayup
2023-09-28 17:47:53
- #1
The question of whether to use open or closed dewatering is immediately clear with such groundwater levels. Of course, we carried out a closed dewatering system. You often read that open dewatering would still work up to a lowering height of 0.5m. I myself have not yet seen this in practice; you will also find relatively little about it online. This requires a lot of space on the property because a pump sump, drainage trenches, and a very low slope angle are necessary. This means, conversely, that a lot of soil has to be moved. This quickly becomes uneconomical, as not everyone has the space to store the additional excavation on the property. The whole spectacle of lowering is over again in 2 weeks (for a typical single-family house). We also did not lower the groundwater level 0.5m below the base of the excavation as is often mentioned; in fact, 20-30cm are sufficient here. The 0.5m is a safety margin from theory that appears in some formulas.
A Kf-value of/from something does not help you. Do you have a soil report available? The geologist surely said something about the prevailing Kf-value under the section groundwater/dewatering. Did he give a recommendation for a dewatering system? All of this was described in detail in my report. Is there a diagram with the grain size distribution in your report? According to your shown borehole profile, your soil is rather sandy and less gravelly, which makes the correct choice of dewatering method a bit more difficult. If I could see more data from your geological report, I could tell you if there is a possibility to drain by gravity (wells) or if vacuum lances must actually be used.
In general, I would choose the time of year with the lowest water level for groundwater lowering; a good planner will already recommend this in the first meeting. Could you discharge the water into a nearby stream, river, or very large field, or does it have to be directed into a sewer? In which federal state is the construction taking place?
A Kf-value of/from something does not help you. Do you have a soil report available? The geologist surely said something about the prevailing Kf-value under the section groundwater/dewatering. Did he give a recommendation for a dewatering system? All of this was described in detail in my report. Is there a diagram with the grain size distribution in your report? According to your shown borehole profile, your soil is rather sandy and less gravelly, which makes the correct choice of dewatering method a bit more difficult. If I could see more data from your geological report, I could tell you if there is a possibility to drain by gravity (wells) or if vacuum lances must actually be used.
In general, I would choose the time of year with the lowest water level for groundwater lowering; a good planner will already recommend this in the first meeting. Could you discharge the water into a nearby stream, river, or very large field, or does it have to be directed into a sewer? In which federal state is the construction taking place?