Technology Description

In situ chemical oxidation using permanganate is an established remediation technology being applied at hazardous waste sites throughout the United States and abroad. Field applications of ISCO continue to grow and have demonstrated that ISCO can achieve destruction of contaminants and cleanup goals. However, some field-scale applications have had uncertain or poor in-situ treatment performance. Poor performance is often attributed to poor uniformity of oxidant delivery caused by zones of low permeability media, site heterogeneity, and excessive oxidant consumption by natural subsurface materials. A second permanganate ISCO challenge is the management of MnO₂ particles, which are a byproduct of the reaction of permanganate with organic contaminants and naturally reduced subsurface materials. These particles have the potential to deposit in the well and subsurface and impact flow in and around the well screen, filter pack, and the surrounding subsurface formation. This is a particular challenge for sites with excessive oxidant consumption due to the presence of natural materials or large masses of non-aqueous phase liquids (NAPL). This project focuses on (1) diminishing the detrimental effects of site heterogeneities with respect to the uniformity of oxidant delivery and (2) managing MnO₂ aggregation and deposition.

Water-soluble polymers will be used to improve the delivery and distribution of permanganate oxidant solutions within heterogeneous contaminated aquifers. As found in SERDP project ER-1486, water-soluble polymers can be employed with ISCO to modify fluid viscosity, which results in a smoothing of the viscous fluid front between layers of different permeability. This means the oxidant solution will be more likely to enter lower permeability zones with polymer present, as opposed to flow bypass without polymer present. As found in SERDP project ER-1484, water-soluble polymers can be employed with ISCO to also prevent MnO₂ particles from agglomerating and forming large particles that will settle/deposit. Deposition can result in formation of lower permeability areas that additional oxidant amendments will bypass. Water-soluble polymers modify the solution chemistry to enhance their potential to be more readily transported in groundwater.