Inverse characterization of NAPL source zones

Area of Science:

• Environmental Science
• Hydrogeology
• Geochemistry

Background:

• Nonaqueous phase liquids (NAPLs) pose significant risks to groundwater resources.
• Accurate characterization of NAPL source zones is crucial for effective remediation strategies.
• Estimating contaminant mass flux is essential for understanding NAPL behavior and migration.

Purpose of the Study:

• To develop and validate a novel tool for inverse characterization of NAPL source zones.
• To quantify contaminant mass flux from NAPL sources using a hybrid modeling approach.
• To assess the efficiency and accuracy of the proposed technique compared to independent methods.

Main Methods:

• A hybrid solution technique combining Simulated Annealing (SA) and Minimum Relative Entropy (MRE) was developed.
• The SA-MRE method was applied to contaminant transport modeling through a vertical flux plane.
• The technique was validated using a three-dimensional aquifer model with a known NAPL source zone.

Main Results:

• The SA-MRE method successfully characterized the NAPL source zone in a 3D aquifer model.
• Probability density functions and confidence intervals for contaminant mass flux were obtained efficiently.
• Model results were validated against digital images of the excavated NAPL distribution.

Conclusions:

• The SA-MRE technique provides a robust and efficient tool for inverse characterization of NAPL source zones.
• This hybrid approach enhances uncertainty estimation capabilities for contaminant transport modeling.
• The study demonstrates the practical applicability of the SA-MRE method in environmental site assessment and remediation planning.