It is unlikely that water will cause the clay to be drawn into your basement unless it is highly dessicated (many fractures and can be crumbled in your hand).

Clays are essentially resistant to the passage of groundwater through them because they have a fine microstructure which does not readily allow water to pass through it (that is why canal beds are made of puddled clay because it doesn't leak water).  Why have you drilled hole in your waterproofing?

Regards

Andy

Andy Machon

 
 

The holes are part of the waterproofing system. They allow water to come in and reach the inside "French Drain" that then moves the water over to the sump pump where it is pumped out of the home.

The idea of havin gthe French Drain inside seems odd.  Why not put it on the outside of the wall?  This prevents damp entering your structure.  Anyway, it's there now.  If the clay has a high silt content then you may experience problems of inflow from the ground bringing the fine silt with it but this would require a substantial flow. My guess (and that's all it is)is that your foundation will not be undermined, but I'd get it checked out by an engineer who can see the problem at first hand.

Andy Machon