Effect of Geomembrane Ageing on the Diffusion of VOCS through HDPE Geomembranes

This paper describes the migration of four commonly found volatile organic compounds (VOCs) in landfill leachates e.g., benzene, toluene, ethylbenzene, and xylenes through 1.5mm thick high density polyethylene (HDPE) geomembranes. Diffusion and sorption tests were conducted at room temperature (i.e., 22C) on both unaged and 13-month aged geomembrane samples. Ageing of geomembrane was carried out at 85C by immersing in synthetic leachate. The diffusion, partitioning, and permeation coefficients were estimated according to one dimensional diffusive flow equation based on Fick’s second law using a computer program POLLUTE v7. The results have shown that the permeation coefficients decreased by about 35-40% for aged geomembrane, which is probably due to the increase in geomembrane crystallinity of the aged sample. It is concluded that, other things being equal, ageing of HDPE geomembrane will result an improved barrier for diffusion of organic contaminants.