ᐅ Lowering of Groundwater According to Geotechnical Report – Your Experiences?
Created on: 8 Apr 2022 14:42
A
Allthewayup
Hello everyone,
according to the soil report, groundwater lowering is necessary during the basement construction, and it can only be discharged into the sewer system. During the boreholes, groundwater was encountered at a depth of 2.5m (8 feet). The Danube River flows approximately 500m (1,640 feet) away in a straight line, so we had already anticipated this. Over the past few months, we have contacted numerous companies regarding water management. Despite follow-ups, we have never received a response. Either there is no interest in such small projects, or we were told to get in touch again just before the start of construction in autumn. Based on the soil report and the neighbor’s references, we have fairly reliable estimates of the volume of water to be pumped. We have set aside €30,000 for this scope of work but remain uncertain about reliable estimates from the company to be hired. The neighbor had to handle this independently because they did not commission a soil report, and the water only emerged after they had already begun the foundation slab. So it was a chaotic situation that ended after 5 days.
My question to users here with experience on this topic:
What costs did you incur for your water management, and how was it carried out? (open, closed, vacuum systems)
What difficulties did you encounter during implementation?
What would you do differently if you were in the same situation again?
To avoid discussions about “omitting the basement,” it must be said that we absolutely need the space, and on a 300sqm (3,230 sq ft) lot, it would not be possible to build it close to ground level.
according to the soil report, groundwater lowering is necessary during the basement construction, and it can only be discharged into the sewer system. During the boreholes, groundwater was encountered at a depth of 2.5m (8 feet). The Danube River flows approximately 500m (1,640 feet) away in a straight line, so we had already anticipated this. Over the past few months, we have contacted numerous companies regarding water management. Despite follow-ups, we have never received a response. Either there is no interest in such small projects, or we were told to get in touch again just before the start of construction in autumn. Based on the soil report and the neighbor’s references, we have fairly reliable estimates of the volume of water to be pumped. We have set aside €30,000 for this scope of work but remain uncertain about reliable estimates from the company to be hired. The neighbor had to handle this independently because they did not commission a soil report, and the water only emerged after they had already begun the foundation slab. So it was a chaotic situation that ended after 5 days.
My question to users here with experience on this topic:
What costs did you incur for your water management, and how was it carried out? (open, closed, vacuum systems)
What difficulties did you encounter during implementation?
What would you do differently if you were in the same situation again?
To avoid discussions about “omitting the basement,” it must be said that we absolutely need the space, and on a 300sqm (3,230 sq ft) lot, it would not be possible to build it close to ground level.
Allthewayup schrieb:
The route to the sewer (about 25m (82 feet)) runs through the parents' property, so it's not an issue.If your parents live there, you also have daily oversight to ensure "everything is working," which we had as well and is invaluable.A
Allthewayup18 Apr 2022 19:08Nida35a schrieb:
If the parents live there, you also have daily supervision to check that "everything is running smoothly," which we had as well and is invaluable.Do you still remember how high the costs related to authorities were and how many days in total you had to pump? You probably don’t recall the subsidized cubic meters anymore 🙂 That would still be interesting. I found a website that offers various construction formulas for calculation purposes. I entered the data from the soil survey there, and the tool calculated a water volume of 39.55 m³/h (about 10,423 gallons per hour). That would mean I need to size the pump a bit larger. We just went for a walk and looked at an excavation site down the street, which is enclosed with sheet piling, and there’s even a fairly large submersible pump hanging about half a meter (about 1.5 feet) deep in the water channel. They are building an underground garage close to the property boundary, so it’s a full-scale project and not quite comparable. We hope the weather will be on our side and that the groundwater level will be as low as possible during excavation.
I can answer your question about the waterproof cellar.
I have had no problems with leaks for 20 years. Both the architect/site manager and I were very careful to ensure the cellar was built exactly according to the plan. As a precaution, I installed drainage under the cellar shafts in case the groundwater rises higher than expected.
I have had no problems with leaks for 20 years. Both the architect/site manager and I were very careful to ensure the cellar was built exactly according to the plan. As a precaution, I installed drainage under the cellar shafts in case the groundwater rises higher than expected.
gutentag schrieb:
As a precaution, I installed drainage beneath the basement window wells in case the groundwater level rises higher than expected.We have experienced this several times before, then water from the drainage flows into the basement window wells 😳 .
So, we sealed the basement window wells, placed the pump inside the vertical drainage pipe, and pump for 2–8 weeks until the groundwater level has gone down again.