Enhanced In-Situ Remediation of Sorbing Groundwater Contaminants using Engineered Injection and Extraction

Remediation of contaminated aquifers is necessary to protect fresh water resources. Because sorbing contaminants remain attached to the soil matrix, they are difficult to remove by pump-and-treat remediation; thus, sorbing contaminants lead to long-term degradation of aquifer water quality and in situ remediation techniques are preferred for the remediation of sorbing groundwater contaminants. In this work, we investigate the use of engineered injection and extraction as a method of enhancing in situ remediation of sorbing groundwater contaminants. With engineered injection and extraction, a treatment solution that reacts with the contaminant is injected into the contaminated aquifer, and a series of injections and extractions of clean water are performed in nearby wells to promote the spreading of the treatment solution throughout the contaminated aquifer. Using numerical simulations, we investigate the appropriate injection and extraction sequences for a range of sorption parameters and reaction kinetics. We show that engineered injection and extraction lead to an increase in the amount of reaction that occurs between the treatment solution and the groundwater contaminant and therefore enhance in situ remediation.