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The acceptable barrier materials included synthetic flexible membrane liners (FMLs) of various types. One of those most commonly used has been high-density polyethylene (HDPE) geomembrane. HDPE has been selected because of its good chemical resistance characteristics, among others. Background compatibility testing has shown the HDPE geomembrane to be extremely resistant to the leachates that are generated by municipal and residual solid waste landfills. The background testing for design has generally been based on relatively short-term tests that are conducted under extreme conditions to ‘forecast’ service life.
Recently, a municipal solid waste landfill double liner system that was constructed in 1988 was exhumed. The HDPE geomembranes of this liner system had been exposed to varying degrees of leachate since 1989. Samples of the HDPE were extracted from the in-place liner system and were laboratory-tested for physical, mechanical and endurance properties. The selected suite of tests duplicated the test protocol conducted in 1988 as part of the liner system construction quality assurance (CQA) program.
The results of this testing show that the HDPE properties are still within the range of data generated by the original testing in 1988. No degradation in properties was indicated by this testing program. The HDPE had been exposed to the leachate, methane, and static and dynamic stresses for approximately 8 years. The results of this test program support the design selection of HDPE as the synthetic barrier component of this landfill liner system. 相似文献
Results of the two phases (i.e. calcium and sodium) essentially parallel one another in that the alkalinity increases the flow time for a given volume of solution to pass through the geotextile. The effect is more pronounced for pH 12 than for pH 10. A precipitate is formed which rests either upon or within the fabric structure causing the major portion of the increased flow time.
In addition to this blinding and/or clogging phenomenon is a strength reduction in some of the fabrics. Certain polyester fabrics show measurable strength losses, while others do not. The type of polyester (there are over 200 types) is felt to play a major (but unknown) role in this selection process. Considerable research into both surface and internal morphologies seems to be warranted. Future efforts will be targeted in these directions. 相似文献