Geosynthetics clay liners

The design of cover systems is site-specific and depends on the intended function of the final cover—components can range from a single-layer system to a complex multilayer system. To minimize percolation, conventional cover systems use low-permeability barrier layers. These barrier layers are often constructed of compacted clay, geomembranes, geosynthetic clay liners, or combinations of these materials. 

In more recent applications, several types of ET cover designs also have incorporated synthetic materials, such as geomembranes, which are used to enhance the function of minimizing water into the waste. For example, the Operating Industries Inc. Landfill in California has incorporated a soil layer with a geosynthetic clay liner in the design. The cover system for this site will reduce surface gas emissions, prevent oxygen intrusion and percolation, and provide for erosion control.68... 

The U.S. DOE has sponsored the ALCD, which is a large-scale field test of two conventional designs (RCRA Subtitle C and Subtitle D) and four alternative landfill covers (monolithic ET cover, capillary barrier ET cover, geosynthetic clay liner cover, and anisotropic—layered capillary barrier—ET cover). The test was conducted at Sandia National Laboratories, located on Kirtland Air Force Base in Albuquerque, New Mexico.84 The ALCD has collected information on the construction, cost, and performance that are needed to compare alternative cover designs with conventional covers. The... 

Geosynthetic clay liner 10- -10-" Values based on sodium bentonite sandwiched between two geotextiles... 

Geosynthetic Manufactured Geomembrane liner (GML), geosynthetic clay liner (GCL)... 

Barrier Compacted clay Geomembrane Geosynthetic clay liner Recycled or reused waste (low permeability) Asphalt Sand or gravel capillary barrier... 

Petrov, R. J. and Rowe, R. K. (1997), Geosynthetic clay liner (GCL) - chemical compatibihty by hydranUc conductivity testing and factors impacting its performance, Canadian GeotechnicalJoumal, 34,863-885. 

Melchior, S. (2002), Field stndies and excavations of geosynthetic clay liners in landfill covers. In Clay Geosynthetic Barriers. Zanzinger, Koerner and Gartung (Eds.). A.A. Balkema PnbUshers. Lisse. ISBN 90 5809 380 8, pp. 321-330. 

Environmental regulations dictate that landfills and surface impoundments for the disposal of hazardous and non-hazardous waste have liners (base, side-slope, and cover liners) and a leachate (contaminated water that emanates from a disposal site) collection and removal system in order to protect air, water, and land resources. Base and side-slopes of containments are lined with compacted clay or geomembrane (commonly HDPE) or both. Cover liners generally incorporate a foundation material overlain by a clay and/or geomembrane (commonly VLDPE which is more flexible than HDPE) liner. Geosynthetic clay liners may be used in place of clay. The leachate collection and removal system is... 

HDPE geomembranes can be combined with various other components (leak monitoring system, geosynthetic clay liners of high durability, polymer amended sand-bentonite-mixtures, capillary barriers) to form alternative composite liners as reliable and cost effective capping systems (Simon and Muller 2004). Such alternative capping systems are tested and increasingly applied for landfills and for the containment of contaminated sites. 

Fig. 3.24. Friction partners, which were mounted onto the wedges ensuring high friction and firm contact to geosynthetic clay liners and geocompositc dndn specimens...

Fig. 3.25. Examples of vertical displacement vs. time curves of a geosynthetic clay liner specimen as monitored by displacement sensors (Thies 2002 Muller et al. 2004)...

Figure 3.25 illustrates typical displacement vs. time plots measured in the test on geosynthetic clay liners (Thies 2002 Muller et al. 2004). As shown by the graphs, an initial phase of rapid deformation (primary creep) in response to the compressive load is followed by a stable phase of gradual, continuous deformation (secondary creep). Shortly before failure, the speed of deformation increases sharply (tertiary creep or materials degradation) and failure occurs. Similarly to the pipe pressure test, these tests on textured geomembranes are carried out at 80 °C over a minimum of 10,000 h. 

Geosynthetic clay liner 10-15 Limit estimated from short term tensile tests, aging effects or repercussions on shear strength were not taken into accoimt (Koemer and Daniel 1994)... 

Bentonite (geosynthetic clay liner) (pre-hydrated or dry bentonite requiring in situ hydration) - Hydrocarbon resistance - Lower maintenance - Self-sealing properties if punctured. - Pre-hydrated can be laid at performance specification required - Requires a protection layer. - Potential hidden problems at penetrations. - Potential for drying out on slopes - In situ hydration of dry systems to achieve performance specification required - Can be uncertain - Good as geotextile mat protected by layer of soil/ stone Medium... 

Koerner, R. and Narejo, D. (1995) Bearing capacity of hydrated geosynthetic clay liners. Journal of Geotechnical Engineering, 1995 82-85. 

A liner for mannre storage can include a geomembrane, a geosynthetic clay liner, and compacted soil or a nonwoven puncture-resistant geotextile placed under the floor and footings of the facility to reduce the potential for this type of pollution. 

The present authors are of the opinion that the use of geosynthetic clay liners (a thin layer of dry clay powder sandwiched between two geotextiles) as gas-resistant membranes below buildings is not acceptable. This is because the liner relies on the bentonite material becoming wet to form a barrier and this cannot be guaranteed. Even if it is pre-wetted the clay can dry out and crack, which will allow gas to migrate through it. 

Compacted clay liners Bentonite clay liner Geosynthetic clay liners Composite clay liners... 

VEGETATED SOIL COVER -DRAINAGE LAYER -GEOMEMBRANE -GEOSYNTHETIC CLAY LINER -EOUNDATION LAYER HORIZONTAL GAS EXTRACTION WELL -... 

Atlanta, GA—Larry Well, organizer and STP editor, Testing and Acceptance Criteria for Geosynthetic Clay Liners (GCLs) (STP 1308, 18 papers)... 

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