Assessment of alternative protection layers for a geomembrane – geosynthetic clay liner (GM–GCL) composite liner

2008 ◽  
Vol 45 (11) ◽  
pp. 1594-1610 ◽  
Author(s):  
S. Dickinson ◽  
R. W.I. Brachman
Keyword(s):  
Tensile Force ◽  
Thick Layer ◽  
Compacted Clay ◽  
Physical Damage ◽  
Vertical Pressure ◽  
Geosynthetic Clay Liner ◽  
Landfill Liners ◽  
Clay Liner ◽  
Tire Shreds ◽  
Protection Systems

A protection layer is required above geomembrane (GM) – geosynthetic clay liner (GCL) landfill liners to limit physical damage (GM strains and GCL thinning) from an overlying granular drainage layer. A 150 mm thick layer of sand has been found to provide excellent protection at a vertical pressure of 250 kPa. However, the use of sand may not be practical in many cases. Experimental results are presented where the effectiveness of alternate protection systems above one particular GM–GCL liner were examined with 50 mm coarse gravel at an applied vertical pressure of 250 kPa. A 150 mm thick layer of compacted clay and a 150 mm thick layer of rubber tire shreds with a nonwoven needle-punched geotextile (570 g/m2) were found to limit the geomembrane strains and GCL extrusion to acceptable levels. Layered geotextiles performed much better than single layers of geotextiles. A layered geocomposite, with a thick nonwoven needle-punched geotextile in the middle to provide cushioning and stiffer woven geotextiles on the top and bottom to carry tensile force, was able to limit the short term strain to less than 3%, but it was not able to prevent local thinning of the GCL because of the deformation required to mobilize force in the geotextiles.

Performance of engineered test covers on acid-generating waste rock at Whistle mine, Ontario

2006 ◽  
Vol 43 (1) ◽  
pp. 1-18 ◽  
Author(s):  
Celestina Adu-Wusu ◽  
Ernest K Yanful
Keyword(s):  
Acid Rock Drainage ◽  
Geochemical Modeling ◽  
Thick Layer ◽  
Waste Rock ◽  
Test Plot ◽  
Layer System ◽  
Acid Rock ◽  
Geosynthetic Clay Liner ◽  
Clay Liner ◽  
Sandy Silt

This paper presents the design and 3 year field performance results of three engineered test soil covers for the mitigation of acid rock drainage (ARD) at Whistle mine near Capreol, Ontario. Each test cover was a two-layer system consisting of a 0.90 m noncompacted pit-run gravelly sand overlying a barrier layer. The three barrier layers studied were a 0.46 m thick mixture of sand (92%) and bentonite (8%) (SB), a 0.60 m thick layer of sandy silt with about 5% clay (SS), and a 0.008 m thick geosynthetic clay liner (GCL). Each cover was installed on 6.10 m thick acid-generating waste rock and was instrumented and monitored along with a control test plot that consisted of 6.10 m of waste rock. The ultimate objective of the study was to select a suitable cover for full-scale decommissioning of acid-generating waste rock backfilled into the Whistle pit. Results from 3 years of monitoring showed that the GCL was the most effective barrier in reducing percolation into the underlying waste rock. Percolation through the GCL barrier was 7% over the 3 year period compared with 20% and 59.6% through the sand–bentonite and sandy silt barriers, respectively, and 56.4% through the control plot. The overall quality of percolate water from the covered waste rock was much better than that of percolate water from the uncovered waste rock. Aqueous geochemical modeling suggested that percolate water draining the oxidized waste rock was controlled by hydroxides, oxide, and sulphate phases of Al, Ca, Mg, and Fe3+.Key words: waste rock, acid rock drainage (ARD), capillary barrier, geosynthetic clay liner, amended soil systems, percolation, MINTEQ.

Statistical analyses of compacted clay landfill liners. Part 1: model development

1994 ◽  
Vol 21 (5) ◽  
pp. 872-882 ◽  
Author(s):  
Scott B. Donald ◽  
Edward A. McBean
Keyword(s):  
Hydraulic Conductivity ◽  
Geometric Mean ◽  
Model Development ◽  
Statistical Analyses ◽  
Compacted Clay ◽  
Clay Liners ◽  
Landfill Liner ◽  
Landfill Liners ◽  
Clay Liner ◽  
Spatial Correlation Structure

The acceptance of compacted clay liners, from a management point of view, has been a source of major concern because of the uncertainty associated with the hydrogeologic properties of the clay. By examining the flux of leachate through the compacted clay liner of a typical engineered landfill, where the hydraulic conductivity of the clay is represented by a stochastic process, an acceptance protocol suitable for compacted clay landfill liners is derived. Determination of the equivalent hydraulic conductivity of the clay liner is accomplished by comparing the flux of leachate through a homogeneous representation of the clay with the flux obtained by Monte Carlo analyses. Acceptance criteria are subsequently developed based on a statistical technique which calculates the confidence limits about a percentile of a probability distribution as well as about the mean of the distribution. For the landfill configuration simulated, the results indicate that the hydraulic conductivity of a compacted clay landfill liner follows a lognormal distribution and exhibits virtually no spatial correlation structure. In addition, for liners exhibiting a geometric mean conductivity of 10−7 cm/s and a standard deviation of 0.3, the geometric mean value is a conservative estimate of the hydraulic conductivity of the clay, provided the liner is constructed in a series of four 150 mm lifts. Key words: clay liners, hydraulic conductivity, statistical analyses, latin hypercube, equivalent hydraulic conductivity.

scholarly journals Hydraulic and Swell–Shrink Characteristics of Clay and Recycled Zeolite Mixtures for Liner Construction in Sustainable Waste Landfill

2021 ◽  
Vol 13 (13) ◽  
pp. 7301
Author(s):  
Marcin K. Widomski ◽  
Anna Musz-Pomorska ◽  
Wojciech Franus
Keyword(s):  
Hydraulic Conductivity ◽  
Exchange Capacity ◽  
Saturated Hydraulic Conductivity ◽  
Clay Soils ◽  
Compacted Clay ◽  
Clay Liner ◽  
Compacted Clay Liner ◽  
Drying And Rewetting ◽  
Swelling Characteristics ◽  
Shrinkage And Swelling

This paper presents research considering hydraulic as well as swelling and shrinkage characteristics of potential recycled fine particle materials for compacted clay liner for sustainable landfills. Five locally available clay soils mixed with 10% (by mass) of NaP1 recycled zeolite were tested. The performed analysis was based on determined plasticity, cation exchange capacity, coefficient of saturated hydraulic conductivity after compaction, several shrinkage and swelling characteristics as well as, finally, saturated hydraulic conductivity after three cycles of drying and rewetting of tested specimens and the reference samples. The obtained results showed that addition of zeolite to clay soils allowed reduction in their saturated hydraulic conductivity to meet the required threshold (≤1 × 10−9 m/s) of sealing capabilities for compacted clay liner. On the other hand, an increase in plasticity, swelling, and in several cases in shrinkage, of the clay–zeolite mixture was observed. Finally, none of the tested mixtures was able to sustain its sealing capabilities after three cycles of drying and rewetting. Thus, the studied clayey soils mixed with sustainable recycled zeolite were assessed as promising materials for compacted liner construction. However, the liner should be operated carefully to avoid extensive dissication and cracking.

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