Advances in Groundwater Remediation: Achieving Effective In Situ Delivery of Chemical Oxidants and Amendments

Contamination of soil and groundwater by organic chemicals represents a major environmental problem in urban areas throughout the United States and other industrialized nations. In situ chemical oxidation (ISCO) has emerged as one of several viable methods for remediation of organically contaminated sites.

Many of the most prevalent organic contaminants of concern at sites in urban areas (e.g., chlorinated solvents, motor and heating fuels) can be destroyed using catalyzed hydrogen peroxide (H 2 O 2 ), potassium permanganate (KMnO 4 ), sodium persulfate (Na 2 S 2 O 8 ), or ozone (O 3 ) delivered into the subsurface using injection wells, probes, or other techniques.

A continuing challenge for ISCO, as well as other in situ remediation technologies, is how to achieve in situ delivery and obtain simultaneous contact between treatment fl uids, such as oxidants and amendments, and the target contaminants. During the past few years, advances have been made in several key areas including knowledge and know-how associated with: (1) use of amendments for enhanced delivery and distribution of treatment fl uids in heterogeneous settings with zones of low permeability media, (2) use of direct push technology for targeted high resolution delivery of treatment fl uids, and (3) use of monitoring and sensing methods for direct feedback for delivery control and evaluation of remediation effectiveness.

This paper provides a summary of ISCO and highlights ongoing efforts to advance the effective in situ delivery of treatment fl uids, with an emphasis on chemical oxidants and amendments, which can help achieve cleanup goals and protect groundwater and associated drinking water resources.