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.
P
Pinkiponk9 May 2022 08:58Allthewayup schrieb:
... drifting away, and now there’s an attempt to really squeeze the most out of those who are still building despite the high price level.This is what I have occasionally expressed here in the forum—that I do not believe the high prices are justified.I’m happy for you that you have had these experiences and can now do a lot yourself with your friends. I wish you much success and, above all, enjoyment in the process.
A
Allthewayup9 May 2022 10:54Pinkiponk schrieb:
This is something I have mentioned here in the forum before—I simply don’t believe the high prices are justified.
I’m happy for you that you had this experience and can now do a lot yourself with friends. I wish you much success and especially enjoyment with it. I just tried to follow the prices in the offer over the phone and understand why the system is massively oversized, but the vague answers only confirmed my thoughts and perfectly match what you said. It is high time the market is brought back down to earth.
Thank you—I’m now even more excited about what’s coming.
For anyone who might come across this thread in the future, I want to repeat something I was already convinced of and now have in black and white:
The quoted prices for providing pumps, settling tanks, hoses, etc., are even higher than the prices for purchasing this equipment outright. Imagine going to a car rental company and paying €45,000 for a mid-size car for a rental period of 4 weeks (about 1 month). I am speechless.
A
Allthewayup9 May 2022 13:55Nida35a schrieb:
You mentioned that the water level is currently being lowered at another construction site.
Take another close look at this with your current knowledge.
Maybe you can estimate the volume of water in liters between two activation points in the sand container, etc.? I had an in-depth conversation with the excavator operator. Since the excavation pit is surrounded by a sheet pile wall, the volume of water is not relevant to me. What was important, though, is that the groundwater was encountered at 2.5m (8 feet) below ground level. So, there is again a match with my data. The water was pushing up through the excavation from below, but he said it’s just a matter of time until that pressure eases off. The positive aspect is that the aquifer is only about 2.7m (9 feet) thick—that is, the water column between the impermeable layer and the top of the groundwater level. It could have been 5 or even 10m (16 or 33 feet), which would have made the situation very different.
A
Allthewayup13 May 2022 16:57Update from 13.05.2022:
This morning, I received a call from the environmental agency regarding my application and a related inquiry. After clarifying the matter, I was told that everything looks good and that the (positive) approval will be sent to me by mail in the next few days. Great.
A remark about a separate application related to crossing public traffic routes led me to a conversation with an employee from the traffic department. The outcome is that I have already registered for an online seminar to obtain the MVAS certification. This is a type of proof of expertise for the common rules of traffic safety obligations. This certificate is a mandatory document for the application. Usually, almost all construction companies or site supervisors already have this certification. It costs about 180€ and takes a Saturday of free time. Afterwards, the 5-page application, including the traffic signs and regulation plan, is submitted to the traffic department.
Once this is done, all formal hurdles are cleared and the ordering of the relevant components for the system can begin. I will provide a detailed list of these soon.
This morning, I received a call from the environmental agency regarding my application and a related inquiry. After clarifying the matter, I was told that everything looks good and that the (positive) approval will be sent to me by mail in the next few days. Great.
A remark about a separate application related to crossing public traffic routes led me to a conversation with an employee from the traffic department. The outcome is that I have already registered for an online seminar to obtain the MVAS certification. This is a type of proof of expertise for the common rules of traffic safety obligations. This certificate is a mandatory document for the application. Usually, almost all construction companies or site supervisors already have this certification. It costs about 180€ and takes a Saturday of free time. Afterwards, the 5-page application, including the traffic signs and regulation plan, is submitted to the traffic department.
Once this is done, all formal hurdles are cleared and the ordering of the relevant components for the system can begin. I will provide a detailed list of these soon.
A
Allthewayup2 Jun 2022 19:47Update from 02.06.2022
The official approval arrived this week. This means that the water management plan is finally authorized. The conditions are quite minimal (e.g., maximum particle size/amount allowed to enter the sewer system, etc.). The cost for the approval was "only" just over 300€ (about $320), whereas we had expected around 1,000€ (about $1,070). So, a reason to be happy for a change 🙂
Almost all the equipment has now been purchased, and the basement is filling up, even though it was supposed to be emptied soon for demolition.
In the meantime, I attended a Saturday seminar to obtain the certificate for the so-called "Person Responsible for Traffic Safety at Construction Sites in Public Traffic Areas" (~180€ / about $190). This is required when applying for a road closure or excavation work permit on public property with the city or municipality – here referred to as an "application for traffic management order." Since we need to cross the pedestrian and bike path to reach the sewer, a half-lane closure is necessary, which requires attaching a traffic sign plan to the application. However, because there is no impact on traffic lights or vehicle traffic, no standard traffic regulation plan was needed. By the way, these are divided into different standard plans. We also had to include a site plan, of course the application form, and the obtained certificate.
As with the environmental office, the traffic and civil engineering department was quite surprised that the builder is handling all of this personally. Therefore, a site meeting will take place soon to precisely coordinate the civil engineering work (which is very limited) and the traffic management. Civil engineering on public property is only allowed to be carried out by companies registered in a special city register. This mainly ensures that certain standards are met and liability is clearly defined. I believe we will manage this too and find a solution together that allows everyone to save face.
The official approval arrived this week. This means that the water management plan is finally authorized. The conditions are quite minimal (e.g., maximum particle size/amount allowed to enter the sewer system, etc.). The cost for the approval was "only" just over 300€ (about $320), whereas we had expected around 1,000€ (about $1,070). So, a reason to be happy for a change 🙂
Almost all the equipment has now been purchased, and the basement is filling up, even though it was supposed to be emptied soon for demolition.
In the meantime, I attended a Saturday seminar to obtain the certificate for the so-called "Person Responsible for Traffic Safety at Construction Sites in Public Traffic Areas" (~180€ / about $190). This is required when applying for a road closure or excavation work permit on public property with the city or municipality – here referred to as an "application for traffic management order." Since we need to cross the pedestrian and bike path to reach the sewer, a half-lane closure is necessary, which requires attaching a traffic sign plan to the application. However, because there is no impact on traffic lights or vehicle traffic, no standard traffic regulation plan was needed. By the way, these are divided into different standard plans. We also had to include a site plan, of course the application form, and the obtained certificate.
As with the environmental office, the traffic and civil engineering department was quite surprised that the builder is handling all of this personally. Therefore, a site meeting will take place soon to precisely coordinate the civil engineering work (which is very limited) and the traffic management. Civil engineering on public property is only allowed to be carried out by companies registered in a special city register. This mainly ensures that certain standards are met and liability is clearly defined. I believe we will manage this too and find a solution together that allows everyone to save face.