Properties of Barrier Components in a Composite Cover after 14 Years of Service and Differential Settlement

• Published in: Journal of geotechnical and geoenvironmental engineering 2017-09, Vol.143 (9)
• Main Authors: Scalia, Joseph, Benson, Craig H, Albright, William H, Smith, Benjamin S, Wang, Xiaodong
• Format: Article
• Language: English
• Subjects: Technical Papers
• ISSN: 1090-0241; 1943-5606
• DOI: 10.1061/(ASCE)GT.1943-5606.0001744

AbstractA case study is presented describing the effects of age (14 years) and differential settlement (≈0.3 m vertical over ≈0.4 m horizontal along a horizontal distance of ≈10 m) on the engineering properties of a soil barrier layer, a geosynthetic clay liner (GCL), and a geomembrane within a composite cover. Samples of the soil barrier layer had hydraulic conductivity below the design requirement of 5.0×10−7  m/s, except in areas that were cracked because of differential settlement. Tests showed that the geomembrane exceeded design specifications for tensile yield strength (≥22.9  kN/m) and elongation at tensile yield (≥13.0%), and current standard specifications for oxidative induction time (≥100  min) and stress crack resistance (≥500  h). Geomembrane seams also exceeded design specifications for peel strength (≥15.9  kN/m) and shear strength (≥22.9  kN/m). Geosynthetic clay liner samples showed a reduction in swell index relative to the as-built condition (from 27.9 to 21.0–24.5  mL/2  g) because of cation exchange. However, all GCL samples had hydraulic conductivity below the design requirement of 4×10−11  m/s.