Leaking Underground Garage Wall at Base

[ajk1]

Please refer to the attachment.

An existing 2 story below-grade parking garage (below a superstructure office building) built in 1955 was leaking in the lowest storey in a number of locations around the garage. There is most probably the remains of the old soldier piles and lagging on the exterior side of the wall.

Within the last few weeks the leak locations were injected with polyurethane (several times) and that seems to generally have stopped the leaks except very near to the bottom of the wall. Have not determined if the leak is:

a) from above the top of the floor slab-on-grade, thru the wall, or
b) from below the top of the floor slab-on-grade, thru the wall, or
c) through the joint between the floor slab-on-grade and the wall.

The exterior side of the wall is a municipal sidewalk up tight to the wall and then the city main street. Digging down would be very expensive and disruptive.

Any suggestions on how to stop the leaks that are very near the bottom of the wall?

I wonder if drilling down into the wall, below the level of the top of the floor, with injection holes that are at an angle to the plane of any potential vertical cracks and injecting, would help?

Could possibly also urethane inject the vertical joint between the edge of the slab-on-grade and the wall.

Or would chipping out the metallic grout and placing crystalline grout in the reglet be better than injection?

Is there anything that could be injected behind the wall by drilling thru the wall from the interior side?

 

[darthsoilsguy2]

the biggest risk with urethane injection is filling a foundation drain and/or drainage media full of urethane and actually increasing the leakage and/or hydrostatic pressure. the urethane injection people act like consultants in sales but put on their contractor hat when it comes to the work and make themselves immune to damages to exterior utility systems in their contracts. always want to understand what drainage systems are in place before going that route, especially when you get to the bottom where foundation drains might live.

an idea that i've pitched a couple of times in recommendations but haven't seen anybody take the bait. how about putting a continuous curb in? maybe an 8"x8" member... or 12"x12". waterproof the joint with a compatible crack repair (i.e. crystalline grout) and waterproof the curb faces of the existing wall and floor with crystaline (Xypex)... maybe even tool in waterstop(s) into the slab (and maybe wall too) to be cast into the curb... provide anchorage to hold the curb into place. waterproof all the construction joint breaks in the curbing. i'm keeping it a little vague in this post since there is structural movement considerations out there.

 

[ajk1]

To darthsoilsguy2 (Geotechnical):

An excellent point about the danger of filling a drain with the urethane, especially if they inject into the earth behind the wall.

I like your idea of a watertight curb, but it would have to have a drainage outlet somewhere...but I suppose that could be arranged.

 

[JedClampett]

Sometimes the best fix is no fix. It's a parking garage. Is a little water bothering the cars?
I'd try to live with it. Add some floor drains.

 

[darthsoilsguy2]

the curb i have in mind is actually flush to both wall and slab. making the water path have to get through the joint and along the waterproofed/waterstopped cast-against exterior-face of the curb. the casting new concrete against 2 different existing members is the structural movement item i mentioned.

a watertight curb/wheel stop water barrier is also an approach if you can make a place to collect and pump from but i would bet that the Owner will want dryness if they are going to spend money.

 

[ajk1]

To JedClampett (Structural); It is a bother to the person exiting his/her car that has to step out from the car into 50 mm deep puddle, wouldn't you think?

Adding some floor drains is what is currently contemplated, but requires breaking up the slab on grade and installing drain pipes below. Thought that perhaps with some thought that something a little more elegant and/or cost effective could be devised, but maybe not.

To darthsoilsguy2 (Geotechnical)- not sure I understand what you describe. Are you saying that the new curb would be cast against the interior face of the existing concrete wall, and that you would somehow make the vertical interface between the new curb and existing wall face watertight? Similarly for the joint between the bottom of the new curb and the top of the existing slab-on-grade? That is a tall order. The water would just come our somewhere else I expect.

 

[oldestguy]

For residential basement leaks some have gouged a shallow "trench" in the concrete along the walls for collecting the seepage and they direct the seepage to a sump for pumping out or a floor drain.

 

[darthsoilsguy2]

you must view the curb as protecting the waterproofing. waterproofing and waterstop elements involved in my scenario sort of making the water cross 3 bridges (through the joint that is crystalline grouted, across the crystalline surface between the curb and existing wall/slab, and around the new bentonite waterstop). The concrete curb serves a cover/protection material for negative side waterproofing to wall/slab elements. The curb will have positive side waterproofing for the curb element itself so that the focus is the new/existing joint. The concrete also encapsulates and activates tooled-in bentonite waterstop strips (or direct applied which is easier/structurally better but not as good from a waterproofing perspective). with regards to water popping up somewhere else... waterproofing can be an iterative process, as you are aware in the original post. The longer and more convoluted the flowpaths, the more likely to stop water penetration. bentonite waterstops do great work at stopping penetration through newly made joints... the biggest concern being to hold down the new structure from being lifted or spalling from the expansive power of waterstop. anyway... i haven't been able to implement this repair but have recommended it a few times as an option on some specific jobs i've worked on knowing i may have had to sleep in the bed i made.

 

[ajk1]

To darthsoilsguy2 (Geotechnical)- ok I now understand your concept. As you note, the expansive bentonite may pop the concrete unless confined by rebar in accordance with the bentonite literature. I am reluctant to try it without having a precedent to refer to that shows it has worked.

To: oldestguy (Geotechnical): I rather like that idea. I'll give it some thought. Thanks. Although this is a commercial building and not a house, maybe it would still be acceptable.

 

[darthsoilsguy2]

understand the need for case studies. like i said, i have pitched this and not had owner buy-in. more just putting it out there for the general internet public since it never found a home on my projects. to be honest, part of the appeal for me is the whole concept of redefining negative-side waterproofing as positive-side waterproofing by changing the frame of reference.... there are a few truths in waterproofing and the one most know is that positive-side applications are the best shot and negative-side applications require managed expectations

 

[ajk1]

To darthsoilsguy2 (Geotechnical): it is an intriguing concept but I think that it is still a negative side waterproofing and what may happen is that it will force the water upward in any existing wall crack that extends both above and below the top of the new curb, and the water will then leak thru above the curb. It would work I suppose if you built the curb the full storey height. But I will give it more thought. Thanks.

By the way I don't see any sump pits in this building so I suspect there may not be any perimeter weeper system.

 

[oldestguy]

Those perimeter channels are cut with a concrete saw, plus some hand work, and don't really show up much at the wall joint.

 

[hokie66]

I doubt that you will ever stop the leakage. Providing a floor drainage system is probably the way to go.

 

[ajk1]

To Hokie66 - ok, yes that is likely what we will do.