This study involved a demonstration of a novel remediation technology for brine-impacted soil at a site in Osage County, Oklahoma, which was recently contaminated with produced-water brine from a leak in a steel line leading to a saltwater disposal well. At this site, topsoil was underlain by clay-rich subsoil, which had resulted in leaching and transport of brine components from the site to an environmental receptor (farm pond) downgradient. Encouraging further movement of brine components using natural drainage patterns would have only further contaminated the pond. A subsurface drainage system was installed to intercept brine components, enhance the lateral subsurface transport process, and prevent further contamination of the pond. Chloride and sodium concentrations in the soil were reduced by an average of 93 and 78%, respectively, in the 4 yr after the subsurface drainage system was installed. More importantly, approximately 95% of the site revegetated during this period. This is in stark contrast to the complete lack of vegetation before the current work was initiated.
A thick layer of prairie hay was applied across the surface of this site after the subsurface drainage system was installed. In addition to limiting the rate of evaporation from the site, this organic material appears to have also been a significant factor in desalination and revegetation of the site. The fibrous hay enhanced leaching after mechanical disruption of the soil and provided soil organic matter that helped to build soil structure and sustain the soil ecosystem.
Based on the results from this study, a two-step remediation strategy for brine-impacted topsoil is proposed. The first step involves the tilling of hay and fertilizer into the soil, whereas the second step involves a subsurface drainage system, if necessary.