Evaluation of the performance of bituminous geomembranes (BGMs) as vapour barriers

Abstract

Vapour barriers (VBs) are essential in maintaining the indoor air quality of home basements or industrial facilities, especially when subsurface contamination poses a risk to human health. It is of utmost importance that the material installed as VB has the capacity to prevent contaminant migration into the indoor air space and reduce its concentration to an acceptable limit. Bituminous geomembranes (BGMs) have been used as contaminant barriers in spite of the gap in research regarding the permeation of volatile organic compounds (VOCs) through BGMs. This study examines the performance of a 4.1mm thick elastomeric BGM as a diffusive barrier to four commonly found VOCs; benzene, toluene, ethylbenzene, and xylenes (BTEX), utilizing computer modelling of contaminant migration from a contaminated soil source to a hypothetical warehouse building constructed on a brownfield site. The effectiveness of BGM in preventing vapour intrusion is evaluated based on its capacity to keep the indoor air concentration of the contaminant below the recommended exposure limits (RELs). Based on the modelling results, the BGM can be expected to perform as a very efficient VB for the simulated warehouse if quality control can be ensured during installation. This modelling approach can be adopted to investigate BGMs’ performance in different remediated site scenarios to make scope for a robust decision-making process regarding the construction and the engineering control requirements.