Groundwater level in clay soils by color

[Grouser]

I was reading another thread regarding GWL uncertainty in clay soil and it reminded me that the historic GWL can be approximated by where the clay changes color from brown to gray. This is the result of the oxidation of ferrous iron Fe+2 into ferric iron Fe+3 by oxygen above the water level, or at least that's the way I remember it. Comments are welcome. Obviously this technique works only when other chemicals don't confuse the issue. Anyway that's my tip for what it's worth.

Happy bore hole logging!

 

[cbosy]

It is commonly done in the Chicagoland area when wells are not installed. If you have any below grade functional spaces that could get wet, you'd better put a observation well in, however. That will be the first thing a forensic investigator will be doing if there are any water problems in the future.

 

[coneboy]

I have used this GWL estimation procedure many times in the past on projects on the west coast. Works great.

I think most of our junior staff members are shown this procedure on there first day of logging boreholes.

Coneboy

 

[Grouser]

A Follow Up

As a qualifier to my original post, I noticed a post in another thread from one of the experts that the color change indicates the oxidation of the iron but does not indicate the oxidizing agent. In other words, the iron could have been oxidized by something in the water and the color change would falsely indicate a lower water level.

I completely agree and appreciate the opportuinty to clarify the information.