About Us
GDT LINING SYSTEMS has operated in the area of geosynthetics since 1993. We are a medium-sized business which specializes in complex and remote area projects. We operate in Northern Australia and PNG.
The lining system typically consists of multiple layers including: a compacted and controlled earth base of low permeability, a GCL, a layer of HDPE, a protection geotextile, a gravel drainage layer and a high permeability filter geotextile. Gone are the days that a compacted clay layer alone was used without question to provide the required impermeability to contain waste.
GCL’s are a layer of bentonite powder or granules held between two layers of geotextile.
The upper cover layer is usually a non woven geotextile. The lower carrier layer is usually a woven geotextile. The two layers contain the bentonite and are held together by needle punching fibres between the two layers. The internal friction capacity of the GCL is important as it may have to resist severe externally applied shear forces. The external friction planes between the GCL and the subgrade and the GCL and the HDPE or other cover materials are also important as it dictates the stability of the whole system. Extensive testing is undertaken to provide frictional data which can be relied upon in the design process. Other critical measures of the GCL are Permeability, swell index and fluid loss.
The HDPE layer usually sits over the top of the GCL and provides additional impermeability. HDPE is thermally bonded or seamed and the process is usually quality assured with a suit of standard testing being conducted.
A Protection Geotextile is used to protect the HDPE from the overlaying granular filter layer, to stop the gravel getting pushed through the HDPE due to the pressure from the overlying waste. The whole system is usually tested using a sample of the actual gravel filter and the proposed HDPE and protection geotextile. It is possible to do a numeric model to estimate the thickness of the geotextile based on defined gravel properties. This can then be verified by testing.
A filter geotextile is usually a light high permeability non-woven geotextile which sits on top of the gravel filter layer. The filter geotextile is required to have UV resistance because it may be exposed to the elements for a prolonged period. Where UV resistance is inadequate a woven product may be placed over the filter layer to provide the required resistance.
GDT LINING SYSTEMS CAN BUILD THE LINING SYSTEM FOR YOUR LANDFILL PROJECT.
GDT provides a turnkey liner supply and installation service for landfill projects including CQA testing of geosynthetic materials.
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