Technical Studies


Development of Electrical Resistivity Tomography Monitoring Technique in

Currently the study of soil and ground water contamination in Taiwan has recently
initiated in-situ remediation phase. The distribution of the chemical agents after injection is a
key factor for the remediation effectiveness. In practice, however, injection into low
conductivity layer (such as silt-clay layers) are difficult as most of the treating agents would
most likely be dispersed into high conductivity layer (for example, sandy layers).
Consequently the contaminant within silty or clayey layers could not be easily remediated and
would continuously affect the underground water environment. In order to enhance site
remediation effectiveness, site operators can adjust the parameters of the injection plan
according to the in-situ monitoring result on the dispersed radius of chemical agents.
Electrical Resisitivity Tomography (ERT) is an effective geophysical technique to monitor the
distribution of in-situ injection by measuring the electrical properties distribution of the
underlying ground layers. Conducting both surface ERT and borehole ERT within existing
monitoring wells can greatly increase the resolution in depth compared to conventional
surface ERT survey. However, proper application guideline for optimizing field survey
parameters is not readily available yet. Moreover, with the intention of utilizing the existing
monitoring well for borehole ERT survey, a recoverable borehole electrode and cable should
be developed for economical and convenience purpose. Aim of this project is to 1. Study the
optimized field parameters of electrode array setup 2. Develop a recoverable and mobile
borehole electrode and cable. This project will eventually examine the aforementioned study
in an in-situ contaminated site, by applying ERT to monitor the dispersed region and path and
examine the in-situ application recoverable borehole electrode-cable system.