Field Inspection of Corrugated HDPE Pipeline Network under Heap Piles at a Copper Mine Site in Chile

Abstract

In-service conditions of a corrugated high density polyethylene (HDPE) pipeline network embedded within a bioleaching pad in the Atacama Desert in Chile were assessed. The pipes provided air for the copper extraction process and were subjected to large overburden stresses generated by the ore heap pile. A pipe crawling device was developed for the study. The field data collected revealed that the pipes were suffering from excessive deflections, circumferential shortening, and flexural bending. Wall buckling was observed in some sections. The flexural bending affected the pipe joint integrity. Field data also revealed localized punctures at some locations because of ore rocks pressing against the pipes. A few sections showed reversed curvature and joint failure. These conditions can generate a loss of functionality for the pipeline system. After a review of the construction record, it was determined the distresses were a result of using inappropriate backfill material and a poor installation procedure.