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Geosynthetics for Alaska landfill closure

Case Studies | February 23, 2022 | By:

Solmax provides a combination of geosynthetics for Alaska landfill closure project with multiple geotechnical challenges.

Photograph of the installation of geosynthetics for Alaska landfill, Homer, Alaska
Installation of geosynthetics at the Homer Solid Waste Facility landfill in Alaska. Photograph courtesy of Solmax

Kenai Peninsula Borough in southern Alaska needed to complete phase two of a landfill-closure project at its Homer (Alaska) Solid Waste Facility. This involved the closure of 226,000 square feet (21,000 m2) of the landfill using a geosynthetic clay liner (GCL), and the installation of a drainage and landfill-gas system. Qayaq Construction LLC, the contractor, selected Solmax to supply the geosynthetics needed.  

Site conditions

Homer’s subarctic coastal climate can be unpredictable, leaving tight windows for deployment. In addition, a road to the east of the landfill-closure operation was open for public access during much of the work. Coordination between normal landfill operations and the closure also had to be considered.  

Homer’s subarctic coastal climate can be unpredictable, leaving tight windows for deployment.

In terms of physical site challenges, the landfill closure involved extremely steep gradients and poor subsurface conditions. Differential settlement was also a concern.  

Chosen geosynthetics for Alaska landfill closure

With geosynthetic designs, including GCLs and drainage nets, proving successful for previous phases of the Homer landfill closure, the Solmax geosynthetics selected by Qayaq included 231,000 square feet (21,450 m2) of BentoLiner NWL-35 GCL; a similar amount of 250-mil (6.35-mm) Fabrinet geocomposite; and 47,360 square feet (4,400 m2) of 40-mil (1-mm) double-textured linear low-density polyethylene (LLDPE) geomembrane

BentoLiner is a versatile, fabric-encased GCL. It is intended for moderate-to-steep slopes and moderate-to-high load applications where increased internal-shear strength is required. The FabriNet geocomposite met the necessary criteria for drainage, filtration, and puncture protection. The double-textured LLDPE geomembrane added frictional resistance, having been designed for applications that require increased elasticity and multiaxial break resistance where differential or localized settlements may occur, such as in landfill closures. This an innovative combination of geosynthetics for Alaska landfill closure.  

To ensure full conformity and add further security, Solmax provided additional third-party testing of its shear and permeability results.

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