Solvent release into a sandy aquifer 3: enhanced dissolution by methanol injection.

Area of Science:

• Environmental Science
• Hydrogeology
• Geochemistry

Background:

• Dense nonaqueous phase liquids (DNAPLs) are significant groundwater contaminants.
• Chlorinated solvents pose persistent environmental risks due to their low solubility and density.

Purpose of the Study:

• To investigate the dissolution of a chlorinated solvent mixture in a sandy aquifer.
• To evaluate the effectiveness of methanol/water injection for enhancing DNAPL dissolution.

Main Methods:

• A field experiment was conducted in a shallow aquifer at Canadian Forces Base Borden.
• Dissolution rates were monitored for 220 days.
• Methanol/water mixture was injected to assess remediation enhancement.

Main Results:

• Dissolution of chloroform, trichloroethylene, and tetrachloroethylene was studied.
• Methanol injection showed limited effect, attributed to the DNAPL's thin, extensive pool distribution.
• Precise DNAPL location is critical for successful remediation.

Conclusions:

• The distribution of DNAPL significantly impacts the effectiveness of in-situ remediation techniques.
• Accurate subsurface characterization of DNAPL source zones is paramount for designing effective cleanup strategies.