drilling thru earth retention pond dike

[AskTooMuch]

Inside our plant we have decades old, man-made lakes/retention ponds for firewater and all other water needs.
Dike around the ponds is made of soil and small crushed rock on the surface.
We have a project where new above ground pipes will be running along the side of the dike.
We'll put it as close to the edge of dike crown and sloping portion.

My question is about the foundation which will be helical/screw piles and geotech soil boring.
These ponds have clay liners and I'm not sure of potential breach of the dike/pond.
Contractor plan on drilling up to 50' for soil boring.
The helical piles will probably just be 30' max and 2' dia.

 

[oldestguy]

If you use casing for the pile installations,likely no problem. Less of a problem potential if ponds are dry at the time.

 

[cvg]

in general, installing pipelines on top of a dam and drilling holes through the dam are not recommended due to potential failure modes resulting in leakage or breach

 

[BigH]

A sketch would be useful.; is this a typical liner against the inside face of the dyke or is it a standard type clay core in the dyke (as for a zoned earth dam)? For water retaining dams, as cvg indicated, drilling is not recommended into the clay; from my understanding of the USBR latest manuals, only auger or sonic drilling is to be permitted into the clay core. In your case if this is a thin layer clayey inside surfacing, actually drilling into the liner may not be necessary (why a sketch would be helpful) - but in any case, I would suggest that any drilling be limited to auger or sonic.