Groundwater Modeling

Groundwater evaluations are often conducted using models, which are an essential tool in quantifying, understanding, and predicting the behavior of groundwater systems. Models can range in scale and scope from water resource evaluations in large regional groundwater basins to analysis of contaminant mobility through small sites.  Exponent utilizes both analytical solutions and groundwater models to address questions regarding the future behavior of a groundwater contaminant (e.g., how far will a plume of contaminated groundwater travel in a certain time, and how will the concentrations change?) as well as release reconstruction — that is, looking back in time (inverse modeling) to determine the cause(s), source(s), and timing of past releases.

Groundwater evaluations often address questions such as:

  • How many water supply wells can a particular basin support, and what yields can be expected?
  • Where, how many, and how deep should wells be placed to intercept a particular groundwater plume of contaminants? 
  • What is the earliest (or latest) date that a release could have occurred from a particular source, such as a underground storage tank (UST), to explain the occurrence of contamination in a distant well?
  • Of the range of remedial measures available to treat a contaminated plume (e.g., slurry wall and extraction system, reactive barrier, pump and treat), which would be most effective and cost-efficient? 
  • How long would it take for a particular surface release to reach groundwater at a depth of 100 ft?

How Exponent Can Help

Our hydrogeologists and hydrologists have extensive experience in model selection, design, and application for a wide variety of problems and geological settings. We have broad expertise in numerous types of groundwater models, ranging from simple one-dimensional spreadsheet models to sophisticated numerical stochastic coupled flow and transport models. Exponent’s groundwater modeling expertise also encompasses flow though the vadose (unsaturated) zone above the groundwater table.

Exponent takes a practical, focused, and cost-effective approach to solving groundwater problems — which starts by asking the right questions, selecting and applying the appropriate technical tools (including rigorously calibrated groundwater models), insightfully incorporating the relevant technical information, and understanding and addressing regulatory and policy issues. We also use state-of-the-practice graphical software to visually convey the key results of our groundwater analyses, so that clients and others can better understand the results and their implications.

We are also commonly asked to assess the validity of groundwater models constructed and used by others. Our understanding of the fundamentals and inherent assumptions used in the construction of groundwater models allows us to evaluate in detail and critique the work of others.

Exponent provides groundwater modeling services in the following areas:

  • Water resource and groundwater basin sustainability 
  • Water rights and water quality 
  • Groundwater and surface water interaction
  • Contaminant transport 
  • Chemical speciation and fate 
  • Soil vapor intrusion 
  • Exposure assessment and dose reconstruction
  • Determining the source(s) and timing of contaminant releases 
  • Evaluating the effectiveness of alternative remediation approaches 
  • Divisibility and allocation of responsibility 
  • Construction dewatering and settlement 
  • Infiltration 

Our groundwater technical team has many years of experience applying groundwater flow and contaminant transport models in a wide range of diverse situations, both nationally and internationally. The team has presented the results of its work in regulatory and judicial settings. Our groundwater scientists and engineers collaborate with other professionals at Exponent who have in-depth expertise in hydraulics, surface water, environmental chemistry, corrosion, exposure assessment, toxicology, geology, and soil science to address challenges with a highly qualified multidisciplinary team.