Preventing Water From Getting To Foundation Level

[YuleMsee]

Hi, I have a ten storey building with shallow pad foundations sitting on friable red clay soil that has descent bearing capacity while dry but it weakens while wet. So I have to prevent the soil at foundation level from getting wet. All rain water downpipes have been directed to a storm water drain outside the property and almost the entire property is paved so rain water percolation is not an issue. Since the land has a slope, I'm afraid water may percolate in a neighbour's property, flow underground and mess the foundation. What options do I have in cutting off such flow and do I have other options in protecting the foundation. Construction is on going, foundations are already cast and we are at 4th flr level.

 

[jayrod12]

Why were your concerns not part of the design process? This seems like a terrible idea all around. A 10 story building on shallow foundations, on clay no less.

Where is the project located?

 

[civeng80]

If all the storm water is draining from the property why are you concerned that water may percolate to neighbouring building ? or are you concerned during the construction period ?

 

[YuleMsee]

@jayrod, the first guy was fired by the client, I'm trying to see if this can be salvaged.
@civeng80, I'm worried water may come from out and mess this projects foundation

 

[dik]

You may be able to draw down the watertable by using a series of well points around the perimeter. You need to contact a geotekkie about the permeability of the soil.

Dik

 

[MotorCity]

At the very least, I would use a perimeter drain system at the base of the foundation with a pump (and a backup power supply).

 

[dhengr]

YuleMsee:
I would want to know more about the prevailing water level, normal water table or a perched water table, on the site, and normal ground water flow across the site. And, I would want to know more about the foundation soils, do they expand and contract with changes in moisture, and how does moisture affect the bearing cap’y? Do you have soils reports for the existing found. design? I would get a good GeoTech guy involved to do some soil testing, etc., and to assist in any new design considerations. Are the found. design and bldg. overturning o.k. with the drier soil bearing values? You could put a french drain across the property, sufficient distance up-slope from you bldg. found., or this could be a cut-off trench filled with concrete to divert any water.