Interstitial hydrocarbons reduce the infiltration rates of coarse-textured reclamation materials from the Athabasca oil sands.

Abstract In the Alberta oil sands, many soils available for reclamation contain portions of oil sand referred to as aggregated oil sand material (AOSM). The objective of this study was to determine the infiltration rates of soils and AOSM from various salvage depths and with various concentrations of interstitial petroleum hydrocarbons (PHCs). The water infiltration rates of AOSM and surrounding soil were determined using a miniaturized infiltrometer, revealing that the soil allows significantly (P < 0.05) greater infiltration than the AOSM. Furthermore, highly-weathered AOSM which originate from the near-surface, exhibit significantly lower PHC contents and greater infiltration rates than medium- and low-weathered AOSM, which are found at depth. The infiltration of 95% ethanol indicates water repellency (WR) is present in both the AOSM and surrounding soil; however, the ethanol results also suggest that the reduced water infiltration rates of AOSM in comparison to the soil, are primarily due to structural differences such as reductions in total porosity and pore connectivity resulting from interstitial PHCs. The diminished infiltration of water into AOSM indicates the ability to slow the downward flow of water and increase the residence time of water in overlying coarse-textured soils, potentially altering the soil water regime and associated ecosite. Highlights • Infiltration rates of coarse-textured materials reduced by interstitial hydrocarbons. • Infiltration rates of coarse-textured materials decrease with increasing hydrocarbons. • Infiltration rates of oil sand increase with increasing extent of weathering. • Infiltration rates of oil sand decrease with increasing depth into the soil profile. [ABSTRACT FROM AUTHOR]