Hello everyone,
We have now completed our preliminary planning meeting. During the meeting, the draftsman mentioned that watertight light wells (WU light wells) might be required according to the geotechnical report. One light well, including insulation, is estimated to cost around 2000⏠(about 2200 USD), and four are planned.
Our quote already includes light wells with drainage, but these are not watertight.
The report states the following:
Seepage water / accumulated seepage water / design groundwater level was not investigated on 10.01.2017.
The soil moisture within the layers examined in the boreholes can be described as dry to very moist. The occurrence of accumulated surface water on fine-grained layers (e.g., silt/clay layers) as well as above the underlying rock horizon cannot be excluded.
The amount of accumulated surface water depends on previous rainfall and can be well managed during construction using surface water pumps (possibly as a dewatering system consisting of drainage ditches/pipes and sump pumps).
Due to experience with similar soils and ground conditions, the design groundwater level should initially be assumed with a safety margin of 1.0 m (about 3.3 ft) above the bottom edge of the slab (~1.6 m (5.2 ft) below the ground surface). A more precise assessment (adjustment related to the presence of oxidation/reduction horizons, i.e., groundwater-affected zones) can be made after inspecting the base of the excavation. Moreover, it is recommended to install a gravel drainage layer around the perimeter in the lower third of the working space in combination with a 0.20 m (8 inches) thick layer with capillary-breaking properties underneath the foundation slab. This ensures rapid distribution of incoming water and regulation of local water ingress.
.....
If executed in watertight concrete (WU concrete) or as a "white tank," the specifications of the WU guideline (DAfStb, 2006), DIN EN 206-1, and DIN 1045-2 apply; the standards DIN 18195-4 and 6 and VOB/C ATV 18336 reportedly do not apply to structures made of watertight concrete. The exposure class 1 according to the WU guideline should be applied. The service life class is to be defined by the specialist planner.
If light wells are installed here, they must be constructed to be waterproof against groundwater pressure or integrated into the overall waterproofing concept, or set at a corresponding height level.
.....
If the light wells were planned as high as possible, wouldnât it be possible to use our âstandardâ light wells instead?
Thanks in advance for your responses.
Best regards
We have now completed our preliminary planning meeting. During the meeting, the draftsman mentioned that watertight light wells (WU light wells) might be required according to the geotechnical report. One light well, including insulation, is estimated to cost around 2000⏠(about 2200 USD), and four are planned.
Our quote already includes light wells with drainage, but these are not watertight.
The report states the following:
Seepage water / accumulated seepage water / design groundwater level was not investigated on 10.01.2017.
The soil moisture within the layers examined in the boreholes can be described as dry to very moist. The occurrence of accumulated surface water on fine-grained layers (e.g., silt/clay layers) as well as above the underlying rock horizon cannot be excluded.
The amount of accumulated surface water depends on previous rainfall and can be well managed during construction using surface water pumps (possibly as a dewatering system consisting of drainage ditches/pipes and sump pumps).
Due to experience with similar soils and ground conditions, the design groundwater level should initially be assumed with a safety margin of 1.0 m (about 3.3 ft) above the bottom edge of the slab (~1.6 m (5.2 ft) below the ground surface). A more precise assessment (adjustment related to the presence of oxidation/reduction horizons, i.e., groundwater-affected zones) can be made after inspecting the base of the excavation. Moreover, it is recommended to install a gravel drainage layer around the perimeter in the lower third of the working space in combination with a 0.20 m (8 inches) thick layer with capillary-breaking properties underneath the foundation slab. This ensures rapid distribution of incoming water and regulation of local water ingress.
.....
If executed in watertight concrete (WU concrete) or as a "white tank," the specifications of the WU guideline (DAfStb, 2006), DIN EN 206-1, and DIN 1045-2 apply; the standards DIN 18195-4 and 6 and VOB/C ATV 18336 reportedly do not apply to structures made of watertight concrete. The exposure class 1 according to the WU guideline should be applied. The service life class is to be defined by the specialist planner.
If light wells are installed here, they must be constructed to be waterproof against groundwater pressure or integrated into the overall waterproofing concept, or set at a corresponding height level.
.....
If the light wells were planned as high as possible, wouldnât it be possible to use our âstandardâ light wells instead?
Thanks in advance for your responses.
Best regards
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