Remediation of brine-contaminated soil using calcium nitrate, gypsum, and straw

Abstract

Salt-affected soils from point source brine contamination are common in the active oil field in SE Saskatchewan. A remediation process that included dewatering by sub-surface tile drains, application of surface amendments (calcium nitrate and straw), and growing forages has been successful but not previously examined. In a field study of two remediation sites, the changes in vegetation, soil salinity, and groundwater were assessed using geo-referenced electromagnetic (EM) maps (EM38h, EM38v, and EM31v), piezometers, and soil sampling. A laboratory soil core leaching experiment studied the effect of gypsum, calcium nitrate, and straw at various rates on the remediation of a brine-contaminated soil. All treatments including the control reduced the electrical conductivity (EC) to non-saline values (<4 dS m-1). The sodium adsorption ratio (SAR) was reduced to <13 with the high rates of gypsum and calcium nitrate. The fastest and most effective treatments were comprised of all rates of gypsum and the highest rate of calcium nitrate.