Monitoring moisture change?

From the GMA Techline

RE: Monitoring moisture change?
There is an opportunity to monitor an application of the enhanced barrier system at a [municipal] hazardous waste site … for which an extension is currently under construction. The consultant, contractor, client, and authority will be monitoring temperature with time. We would, however, like to monitor GCL moisture change with time as well, in this application where the GCL is inaccessible as it will be under 20m of waste.

Do you have any advice on how to measure GCL moisture change in such an application where we cannot recover samples?

(Kind regards from S.A. | South Africa)

Reply: Good to hear from you and about your interesting project. Regarding the measurement of water content of an in situ GCL, the cheap method is to use “soil moisture cells” as do the agronomists. The problem is that they register only up to field capacity and when saturation is reached they become ineffective.

Alternatively, and obviously more expensive, is the use of time domain reflectometry (TDR). The instrumentation used by Kerry Rowe at Queen’s University in Kingston, On., Canada, is from Campbell Scientific TDR 100 system along with CS640 TDR waveguide probes.

Hope this helps,

Bob Koerner | GMA Techline