Landfill Liner Systems Research Articles

Evaluation of groundwater flow regime at a landfill with liner system

Abstract The High Acres landfill is a 166‐acre (67‐ha) sanitary waste disposal site located southeast of Rochester, New York. The site consists of an existing 92‐acre (37‐ha) unlined landfill and a proposed 74‐acre (30‐ha) landfill expansion. To contain the leachate that may be produced at the new site, the construction of a liner system is proposed. According to regulations, the base of the landfill liner system is required to be above the seasonal high water‐table at the site. A multilayer aquifer model was used, therefore, (1) to simulate the mechanism by which groundwater moves through the High Acres site; and (2) to evaluate the average and seasonal high water‐table conditions at the site with and without the liner system. Based on these simulations, critical design aspects of the landfill liner system and its effect on the local groundwater flow regime is evaluated throughout the entire site.

Interfacial friction study of cap and liner components for landfill design

The purpose of this research is to extend the database for interface friction values of the various components of cap and liner systems for proper landfill design with special emphasis on friction under low to moderate normal loads. This relates to periods of cap and liner system construction and long-term cap system stability. Interface friction parameters are presented for three soil types including a conventional sand, kaolinite clay and fly ash; five geotextiles including monofilament, multifilament and slit film wovens, and heatbonded and needlepunched nonwovens: one flexible geogrid; five geomembranes including high density polyethylene (HDPE) with smooth and roughened surfaces, a very low density polyethylene (VLDPE), a chlorosulphonated polyethylene (CSPE) and a polyvinyl chloride (PVC); and one geonet. The various interfaces tested correspond with a typical landfill cross-section. The interface friction results are presented for 71 various interfaces that may exist within a landfill cap or liner system. Finally, detailed descriptions of the method and equipment of the modified direct shear device, as well as a conclusive summary of the analytical results and their pertinence in design are discussed.

Prefabricated bentonite clay liners

The development and use of prefabricated bentonite clay liners is a relatively recent development, even for a technology as young as geosynthetics. There are four currently available commercial products, each of which consists of essentially dry bentonite clay agglomerates (with or without a dry, but water soluble, adhesive) placed on a geotextile or geomembrane carrier layer. Often a covering geotextile is used above the clay, and for two of the products, the entire ‘sandwich’ is needled throughout. For landfill liner systems, the major use of these materials appears to be as the lower component of a composite primary liner. This use is particularly interesting in the light of response action plans (RAPs) which are being required by many regulating agencies. For landfill closure systems, these materials can readily form the lower component of a composite cap system. Of interest here is their possible capacity to follow subsidence of the landfill and their ability to deform in an out-of-plane manner. With the newness and potential of prefabricated bentonite clay liners, however, comes a number of questions. This paper attempts to present these questions and the currently available answers regarding the various products. In concludes by giving a number of suggestions and cautions for field placement based on the authors' experiences to date.