Boring logs

[SF_century]

When looking at a boring log you see a layer of sand above the ground water table should you automatically be concerned w the possibility of liquefaction? Also because o this condition would you choose a drilled pier or a driven pile?

 

[BrewingAz_PE]

There are three things that need to exist in order for liquefaction:

1) groundwater (looks like you have this)

2) loose sand deposits (not sure if the sand is loose or not based on your description)

3) a seismic source, be it earthquakes, vibrations etc.

There is a possibility for static liquefaction where an seismic source is not needed, but I'm guessing from your description that won't happen.