Salt Lake County Tailing Embankment
Tailings experience gradual consolidation settlement as the pore pressure dissipates and the terrain subsides. Monitoring the stability of the tailings facility is indispensable for sustainable mining development. I integrated multiple SAR datasets, SRTM DEM, and LIDAR DEM, as well as water levels, to investigate the dynamics of consolidation settlement over the tailings impoundment area in the vicinity of the Great Salt Lake, Utah [Hu et al., 2017, RSE].
Figure 1. (a) Aerial imagery of the tailings impoundment bounded by the Great Salt Lake to the northwest, wetlands and mitigation area to the northeast, Oquirrh Mountains to the southwest, and residential community Magna to the southeast. The whole impoundment can be classified into two major ponds – the north pond with active tailings deposition and the south pond which has been completely abandoned and reclaimed since 2001. (b) Vertical deformation velocity in the south pond derived from ENVISAT. (c) and (d) show the deformation velocities of ENVISAT (red circles), ALOS-1 (blue squares), and Sentinel-1A (gray triangles) along cross-section profiles AA’ and BB’ (white dashed lines). The left Y axis represents the vertical deformation velocity in millimeters per year and the right Y axis represents the elevation in meters.
Results show that the reclaimed south pond experienced quasi-linear settlements with the largest rate of 200+ mm/yr around the low-permeable decant pond clay from 2004 to 2011, and the rate decreases to 100+ mm/yr during 2015 and 2016. The nearly decadal InSAR measurements can be well-explained by the geotechnical consolidation model, which reveals the long-term exponentially decaying settlement and predicts the settlement process in the near future.
Figure 2. Decadal settlement modeling from 2000 to 2020. (a) Modeling of total settlement at near surface. (b) Settlement process at a selected target (“x” in panels a, c-e, with the amount of deformation indicated by the text below) throughout the tailings structure. (c)-(e) Three settlement components - immediate settlement, primary consolidation, and secondary consolidation. (f) Comparison of cumulative total settlement at the selected target between model and InSAR observations.