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Geocomposite lines Anchorage Regional Landfill expansion project

Case Studies, News | December 13, 2021 | By:

Photograph courtesy Solmax

In 2020, the Solid Waste Services department (SWS) of Anchorage, Alaska, expanded the Anchorage Regional Landfill’s capacity by adding a new cell 9 and tying it to several existing cells in close proximity. Alaska Aggregate Products LLC (AAP) was awarded the geosynthetics and piping contract, and AAP chose Solmax to supply all the required geosynthetics.

AAP installed 650,000 square feet (60,000 square meters) of a geocomposite liner system for the new cell. The liner composite system consisted of Solmax’s NWL-60 Geosynthetic Clay Liner (GCL), an 80-mil (2-mm) double-sided textured high-density polyethylene (HDPE) geomembrane liner and a 16-ounce (450-g) cushion geotextile with an HDPE Leachate Collection Piping System. 

For this project, a site-specific slope-stability analysis was performed by the engineering firm, Bristol Engineering Services Co. LLC. The specifications called for a GCL material that had already been tested and met the requirements. Bristol required interface-shear testing on the NWL-60 GCL to ensure that it met all requirements for site specification, specifically 02078 2.3 C 8: “Interfaces shall have at a minimum a friction angle of 11.5 degrees and a cohesion of 250 psf [12 kPa], or equivalent combination of Mohr-Coulomb strength parameters, across the range of normal loads and displacements tested.”

Solmax performed all testing and provided all the data to show that its NWL-60 GCL exceeded requirements for the specifications. All testing results were delivered on time and without any impact on the project’s schedule.

Two significant challenges facing Solmax were the logistics and long lead times of getting materials to Alaska, while also keeping the project on track during those months when Alaska has the most rain. APP took advantage of every good-weather day by working longer hours, and deploying as much GCL and liner as possible to complete the job on schedule and within budget. Solmax’s logistics department worked closely with AAP and AAP’s freight subcontractor to schedule and ensure on-time delivery of all materials.

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