8.5.3 Instrumentation
To facilitate pillar extraction, in the early 1990s The Doe Run Company and Golder Associates began to investigate the implica- tions of using cemented backfill to surround, or trap, pillars. lt was thought that although these pillars would likely fail less of the backfill, their residual strength might provide support to both stabilize the back and reduce the loads on surrounding pillars.