Transport of Aqueous Organic Compounds in Thermoplastic Geomembranes. II: Mass Flux Estimates and Practical Implications

Abstract

The transient and steady-state mass fluxes were estimated based on partition and diffusion coefficients and compared with fluxes through holes in liner systems under representative field conditions. Stretched high-density polyethylene (HDPE), unstretched very low-density polyethylene (VLDPE), and unstretched polyvinyl chloride (PVC) had 2.0–2.5, 4.4–5.2, and 8.4–10.8 times greater permeabilities than unstretched HDPE, respectively. The maximum instantaneous mass flux decreased by more than 15 times as the initial aqueous concentration decreased from 100 to 10 mg/L and as the HDPE thickness increased from 0.76 to 2.54 mm. The maximum instantaneous mass flux increased by 1.7 times when a HDPE geomembrane was stretched by 5% of its original length. The flux caused by steady-state permeation through the intact geomembrane, which has so far been neglected, was comparable to the flux through the geomembrane with large holes alone but more than three to 34 times greater than the flux through the geomembrane with small holes alone, implying that the permeation through the intact geomembrane may pose serious environmental contamination.