The cost of electrical resistivity monitoring

The cost of electrical resistivity monitoring can be divided in three categories. These are upfront costs, system maintenance costs and costs associated with data acquisition, processing and analysis.

 Upfront costs

Upfront costs include the cost of field hardware (multi electrode resistivity system and multi electrode cables and electrodes), and the associated field-based infrastructure (for instance in many cases a field trailer, power and some kind of communication equipment), as well as system deployment and installation costs. These upfront costs can be substantial: typically they range from thirty thousand dollars for a small system to hundreds of thousands of dollars for large systems.

 System Maintenance Costs

Maintenance costs are the second cost component. These include both costs associated with communications (e.g. wireless data plans), labor costs and costs related to system or component failure. For instance, as electrical resistivity systems are connected to the ground by numerous electrodes they are quite vulnerable to lightning strike damage which may necessitate swapping out part or all of the electronics. Similarly, cables may be chewed through by native wildlife, and wildfires may sweep through areas and burn down equipment. 

While it is hard to completely avoid system failure, maintenance costs can be reduced by implementing robust diagnostic capabilities as part of the system and by having a system design which allows users to field replace modular components (rather than requiring field systems to be sent back across country borders with all the attendant paperwork and costs). In addition, systems can be designed to stop acquisition when lightning occurs in the vicinity. This could reduce the impact of lightning strikes. 

Acquisition, processing, analysis and reporting costs

The final cost components are those associated with data acquisition, processing, analysis and reporting. These are typically all labor costs. 

Note that in academic environments (where research typically occurs as part of PhD projects and where labor is student labor which is “free” or low cost) this labor cost is often not accounted for as a true project cost. However, the same does not hold true for operational environments such as engineering firms or water production companies. In these environments, labor and equipment dollars are equivalent.

Labor required for data acquisition, processing and analysis costs for 4D ERT can be substantial. Getting a precise estimate of these costs is challenging but based on the experience of the authors something on the order of 0.2 full time equivalent (FTE) for each 4D ERT system is probably a realistic (and likely conservative) estimate. 

In order to make electrical resistivity monitoring affordable all costs should be minimized. This motivated the approach by Subsurface Insights to build its own electrical resistivity hardware, and to automate all aspects of data acquisition, processing, analysis and reporting through the use of a cloud based cyberinfrastructure.