In Situ Chemical Fixation Prevents Arsenic Leaching from Contaminated Soil
In Situ Chemical Fixation of Arsenic-Contaminated Soil (1014056).  In long-term laboratory column studies, no detectable arsenic leached from contaminated soils treated with the chemical fixation reagents ferrous sulfate (FS) or ferrous sulfate plus lanthanum chloride (FSLA), even after 280 years of simulated leaching by natural precipitation.  This is good news for electric power companies that own sites contaminated by past use of arsenic herbicides, pesticides, and wood preservatives.  At sites where source removal is too costly or infeasible because a facility is energized, in situ chemical fixation (ISCF) can provide a viable answer to the need for soil treatment because it binds arsenic in place.  In this 3-year study, researchers identified three candidate reagents through a literature review, and conducted laboratory batch and column treatability studies on five characterized soil samples using the reagents.  FS and FSLA performed well in binding arsenic; a proprietary reagent, Metals Remediation Compound®, did not.  To foster regulatory acceptance of the technology, EPRI plans field trials to demonstrate the permanence of ISCF with appropriate application.  For instance, FS and FSLA produce stable results under oxidizing subsurface conditions but their performance needs to be tested under reducing conditions.  For more information, contact Mary McLearn, (650) 855-2487, mmclearn@epri.com.  Note:  See related arsenic articles under Program 42 or 53.