Exhumation of HDPE geomembranes exposed to the weather for 10 years in a gold mining tailing

Abstract

The durability study of a high-density polyethylene (HDPE) geomembrane that has been acting as a fluid barrier for 10 years in a gold mining dam/reservoir in Brazil was evaluated. The system stores waste considered hazardous, according to Brazilian legislation, with an average pH of 8 and presence of a cyanide solution. Samples exhumed after 10 years of service were exposed to the following three conditions: 1- only the weather; 2- contact with waste and exposure to the weather; 3- with field seams in contact with the tailings and exposure to the weather. Tensile strength, deformation under traction, tear resistance, puncture resistance and stresscracking tests were carried out. With the use of statistical tools, the results obtained were compared with the GM13 standard. Through the results analysed, it was not possible to observe significant losses in the geomembrane's resistances or a significant increase in its tensile deformation. It was observed the geomembrane did not present significant alteration in 10 years of service, with stress crack exception. The geomembrane may be able to continue to perform the function for which it was designed. It is necessary to carry out additional tests and monitor the system to understand whether or not its low performance in stress crack test is affecting the flow barrier function.