Controlled release, blind tests of DNAPL characterization using partitioning tracers.

Area of Science:

• Environmental Science
• Geochemistry
• Hydrogeology

Background:

• Dense nonaqueous phase liquids (DNAPLs) pose significant environmental contamination challenges.
• Accurate characterization of DNAPL distribution is crucial for effective remediation.
• The partitioning tracer technique offers a potential method for DNAPL assessment.

Purpose of the Study:

• To evaluate the effectiveness of the partitioning tracer technique for characterizing DNAPL.
• To assess DNAPL volume estimates under controlled release conditions.
• To identify factors influencing the accuracy of the partitioning tracer technique.

Main Methods:

• Four partitioning tracer tests were conducted in an isolated test cell with controlled perchloroethylene (PCE) releases.
• Tests employed different pumping patterns (inverted double five-spot, vertical circulation wells) before and after remediation.
• Blind test conditions were maintained, with researchers unaware of DNAPL release details.

Main Results:

• DNAPL volume estimates varied significantly among different partitioning tracers within each test.
• Tracers with high partitioning coefficients tended to underestimate PCE volume at low saturations.
• Accuracy was potentially hindered by tracer degradation and interference from remedial fluids.

Conclusions:

• The partitioning tracer technique's accuracy is sensitive to DNAPL saturation levels and tracer properties.
• The method's application at low saturations, near its limits, may affect DNAPL volume prediction reliability.
• Further research is needed to optimize the technique and mitigate influencing factors for improved DNAPL characterization.