Hanford Landfill
Cost Effective Alternative to an Unreinforced GCL for Landfill Final Cover
Systems
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Abstract A geosynthetic clay liner (GCL) may be installed at a fraction of the cost of a California prescriptive standard compacted clay liner (CCL) when low-permeability material is not available on-site and soils must be either amended or imported. The engineered alternative selected for the final cover system at the 32 ha (79 acre) Hanford Landfill located in Kings County, California, incorporates a new GCL product that offers a cost-effective alternative to both unreinforced GCLs and the State's prescriptive standard CCL, while exceeding applicable performance standards. Economic analyses comparing three design alternatives demonstrated a 41 to 63 percent cost savings over a prescriptive CCL cover system. This paper discusses the first use of a new, lightweight, woven/nonwoven, needle-punched GCL product in a landfill final cover application and presents results from conformance testing and construction quality assurance monitoring. Bentonite migration has been reported in unreinforced GCLs; however, at the Hanford Landfill, field observations of GCL panels exhumed approximately five weeks after initial placement indicated significant hydration, but no discernable bentonite migration. |
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