One of the largest and most advanced landfill facilities in WA underwent its latest cell construction recently.
Situated at the foothills of the Darling Scarp in Perth, the South Cardup Landfill exhibited some challenging design issues due to its topographic and geotechnical profile.
Cell 7 is a case in point. Its asymmetrical plan and elevation required a cautious design approach in terms of drainage, tie-in with the adjacent cell wall, liner selection and liner cushioning.
Global Synthetics’ solution
Specialist landfill designers working on this project opted for a dual liner arrangement in order to secure high safety factors for leachate containment.
The designers conducted a series of rigorous laboratory load testing, resulting in a selection of Bentofix® geosynthetic clay liner (GCL), Carbofol® HDPE liner and ProFab® heavy weight cushion nonwoven geotextiles.
A specific grade of Bentofix® (BFG 5000) was chosen due to its high-quality bentonite and robust construction. The BFG 5000 also provides trouble-free and cost-effective installation due to its ‘self seaming’ characteristics.
BGF 5000 can be cut and/or overlapped at any point throughout its area without the need for mixing and applying the adhesive paste for manual seaming.
The long steep slopes at South Cardup also demanded an HDPE liner with a high interface friction coefficient.
Carbofol® 2.00mm structured (Megafriction) HDPE liner was selected due to its unique surface texturing. The texture is extruded in the form of nipples which have a very high ‘asperity’ allowing for an excellent bond with the interface geosynthetics (GCL and cushion geotextile).
Three grades of ProFab® cushion geotextiles were selected to protect the HDPE from the sharp aggregate drainage layer above. The selections were based on their relative positions on the cell floor.
● ProFab® AS1200 (1200g/m2) was specified for the deepest zones to cater for the highest waste surcharge loads
● ProFab® AS880 (800g/m2) was chosen for the shallower sections
● ProFab® AS1000 (1000g/m2) for the intermediate regions
The mixture of ProFab® grades enabled the designers and stakeholders the flexibility to economise on material costs.
Help and advice with landfill projects
The team at Global Synthetics can provide high level engineering advice, support and cost-effective solutions for your next project. To find out more, get in touch with our friendly team at email@example.com