DNAPL distribution in the source zone: effect of soil structure and uncertainty reduction with increased sampling...

Area of Science:

• Environmental Science
• Hydrogeology
• Geostatistics

Background:

• Dense nonaqueous phase liquid (DNAPL) contamination poses significant environmental challenges.
• Soil heterogeneity introduces variability in contaminant plume distribution.
• Accurate characterization of DNAPL plumes is essential for effective remediation.

Purpose of the Study:

• To investigate the impact of soil heterogeneity on DNAPL contaminant distribution parameters.
• To quantify the reduction in uncertainty achieved through increased soil sampling density.
• To evaluate the influence of sampling density on DNAPL plume characterization.

Main Methods:

• Numerical simulations of DNAPL releases using stochastic hydraulic conductivity fields.
• Generation of two simulation ensembles based on low and high soil sampling densities (three-fold increase).
• Definition and computation of alternative measures to describe DNAPL plume characteristics.

Main Results:

• Statistically similar DNAPL plumes exhibited qualitatively different patterns (compact to finger-like).
• Uncertainty in plume features varied significantly (20% to 90% CV) with low-density sampling.
• Increased sampling reduced uncertainty by 7% to 69% for different plume variables.

Conclusions:

• Soil sampling density significantly impacts the uncertainty in DNAPL plume characterization.
• Remedial designs should prioritize less uncertain plume features over detailed source zone architecture.
• Geostatistical approaches are valuable for assessing contaminant transport and variability.