Basement Leak Containment with Low Wall

[psychedomination]

Hi there,

I have a project where a portion of the basement of a commercial building is below the water table when there is very heavy rain (not a common occurrence). The water seemed to be leaking out of the joint between the column and the wall and was going under the slab and also soaking the floor on top of the slab.

The room that this is happening in is storing very critical electrical components, so the client wants to get this sorted. They’ve requested a bund type wall to contain the water with a sump pump inside that will pump the water into a waste line above.

In theory the bund shouldn’t be that difficult, I’ll put a few dowels into the existing slab and put a water stop in the bund wall. The wall won’t need to be very high, perhaps only 16” or so. I’m thinking of doing something like this :

First question is whether I should put in two water stops?

Second questions is if it’s possible to do something like this using CMU block instead of forming up a RC wall? I’m guessing a CMU wall wouldn’t work with the waterstop but would appreciate guidance.

Now, bund wall aside, there is another issue where there is a large piece of electrical equipment that is only about 5” to 7" away from the wall in a specific location where the bund wall would’ve needed to be. This would be extremely expensive to move as it is hooked up to some hard-wired electrical lines. How can I waterproof this location when I only have ~5” of clearance? I assume whatever is done here would need to tie into the 2’ wide new bund wall? Any advice would be greatly appreciated.

I’ve included a plan for context below :

Any guidance on this approach or if you think there is a better one, please let me know.

Some additional photos for context :

 

[HTURKAK]

Will you post some pictures around the steel column?

My suggestion will be waterproofing of the concrete rather than allowing leakage and collecting at a pit;

Two options,

- PU pressure waterproofing of the concrete ,

- The use of crystalline water proofing agents (e.g.

https://www.xypex.com/

)

Acc. to my personnel experience, Both options will work ...












Tim was so learned that he could name a
horse in nine languages: so ignorant that he bought a cow to ride on.
(BENJAMIN FRANKLIN )

 

[psychedomination]

@HTURKAK Thanks for the reply!

Not the best photo but this is the corner column where the water was shown to be leaking out, there may be other locations but I feel this is the main one. The column is a steel beam encased in concrete.

Perhaps both waterproofing the concrete and collection pit may work. Waterproofing as the first line of attack and if this fails the bund wall would still protect the expensive electrical equipment.

I'm not too familiar with the PU pressure waterproofing. Would this be suitable to resist the water pressures? Basement level is approximately 20' below grade. Water table rises in heavy rain, I'd guess rises ~ 5' from the bottom of the basement level, which results in the leakage. Is this easy to apply or do you normally need a specialist contractor to carry out this type of work?

I'll look into xypex systems, I always thought this was an additive for concrete mixes but after a quick browse of their website, I see that they offer quite a few different products too.

 

[dik]

Just in case the water problem is as you think, I'd take another gander to make sure this was the condition. The height of that wall indicates that you have some serious water issues, just make sure this will address them. Can you add 'relief' holes in the slab to allow the water to exit easier? and maybe reduce water on the slab soffit? Is there any uplift of the slab? For a waterbar, bentonite rod is ideal for this type of application.

I should have added that this type of problem is best handled by addressing the exterior perimeter of the foundation wall.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[HTURKAK]

- You would need specialist contractor..

- It is not reasonable that the water level rises ~ 5' after heavy rain..

- The last picture implies the leak is at corner and along the wall -slab CJ rather than concrete wall . The foundation system probably spread footings and bottom slab on grade ..

- The CJ can be repaired with XYPEX ..however , the concern is the pore water pressure may build up and uplift od the slab..


I will suggest you, make sure that the WL rise will not uplift the slab for mortar repair from the inside and if necessary, excavate from exterior along the wall and provide drainage .









Tim was so learned that he could name a
horse in nine languages: so ignorant that he bought a cow to ride on.
(BENJAMIN FRANKLIN )

 

[psychedomination]

Hi all, thanks for the responses so far. My dimensions were off in my previous response. Wall height is ~10' below grade. I agree, a 5' raise from heavy rain is not realistic. I'm not sure what this would be though tbh.

Yes, the water is coming out of the corner and most likely at the CJ between the wall and slab (this is evident as there is a separation shown between the elements and I've seen a video of water leaking out of the corner).

After looking at the building foundation drawings it is a combination of spread footings, pad footings and a slab on-grade system.

This is an old building btw and I don't believe the slab has had any uplift issues in the past.

However, if I start making changes to the slab, uplift is a concern of mine. This is why I was thinking of leaving it as is and containing the excess water with a bund wall and removing it with an automatic sump in the rare occurrence that the water table does rise due to rain.

Adding any drainage or relief holes to the slab would mean that the interior water height would match the water table height wouldn't it? I'm a bit concerned about doing that because I'm not sure what the water table height increase actually is.

I guess the client's main aim is to isolate the water in a specific location on the slab to not get any water near the electrical equipment, which is why they requested a bund wall.

If I go this route, the issue remains with the 7" clearance and tying this into the rest of the bund wall.

 

[SWComposites]

Cam you raise the electrical box vertically and put the bund wall underneath it?

 

[epoxybot]

Are the walls resting on the slab or are the walls resting on the footing? The photo that includes the column looks like the concrete slab is adjacent to the wall.

Is that a scratch course on the wall, spoil from construction or previously failing paint? Or was it previously treated with cementitious waterproofing?

 

[RPGs]

Dik is right, the most correct solution is always to re-direct the water from the outside, be it surface water or groundwater.

No client or contractor is happy to hear that answer though. If I were you I would push that line of thinking and prioritize exterior work instead of allowing the water into the space. It just never seems to work and they will keep calling you back.

Also, I always get nervous when a sump pump is the only thing preventing flooding, like during a power outage.