Q&A: Groundwater Modeling

When should groundwater modeling or data visualization be used to support litigation?

The decision to use a groundwater model or data visualization to support litigation is not always straight forward. The Langan Quantitative Hydrogeological Services Group was formed in part to help answer this type of question.

Groundwater modeling and data visualization can be useful to support several types of litigation including insurance litigation, toxic tort, cost allocation and natural resource damages. A groundwater model is an ideal tool when there is a need to predict future conditions of a groundwater flow system. For example, a predictive groundwater model with forward-looking application can be used to estimate how long it will take a plume to reach a receptor or how long groundwater remediation will take. Courts have upheld forward-looking models of contaminant plumes used to establish remedial measures and associated costs when the model is properly applied to represent real-world conditions and can be validated by existing data. A groundwater model may also be used in a backward-looking manner to predict site conditions in the past, such as plume origin, based on current plume geometry and known past and present groundwater flow conditions. Backwards-looking models can help determine contributions and allocation of costs for remediating off-site contamination, but will typically be subject to more rigorous scrutiny by the courts; however, we have been successful in introducing this approach in litigation cases.

Groundwater models are also used to allocate remediation costs among responsible parties based on factors such as predicted contaminant mass contribution or volume of impacted groundwater flowing to a simulated recovery well.

Answer provided by Terrance Stanley, PG, Project Hydrogeologist
Terrance has over 20 years of progressive experience in numerical and analytical groundwater modeling. He has been involved in many modeling projects with complexities ranging from small scale dewatering simulations to regional fate and transport models. He has also prepared personnel for expert witness testimony as well as acting as an expert witness in litigation that involved groundwater modeling and hydrogeological site assessment.