Field Permeability Testing

[NBRY1]

What method would be the simplest to measure hydraulic conductivity in a borehole provided the following information.
About 45-ft of residual soil over rock (Southeastern US, Piedmont). I am interested in the zone just above rock; where backward erosion piping has
been observed exiting a slope. I would guess this zone (where material is moving) ranges from a few inches to several feet in thickness.

Thanks.

 

[fattdad]

Flow nets are required to evaluate piping. The concept of critical gradient has no bearing on permeability. Just not sure what you are striving to determine?

f-d

ípapß gordo ainÆt no madre flaca!

 

[NBRY1]

Appreciate your feedback fattdad.

The intent is to evaluate backwards erosion piping. Permeability is of importance when using methods of Hoffman (2012), Sellmeijer (2011), and Schmertmann (2000). I'm interested in the critical gradient for the progression of piping. The zone of interest is rather complex, and is believed to vary from soil to rock. Judging from the observed pipes, we think the piping is occurring within a soil layer having a rock roof just above it a few inches to a few feet thick and more competent bedrock below.