WALO has created a Dense Asphaltic Concrete (DAC) impermeable landfill barrier system, which is impermeable to methane and leachate, found in most solid waste landfill deposits.

Leachate drainage from landfill cells is always a major concern for waste operators, who are under increasing pressure to prioritise environmental considerations. The application of DAC means that landfill sites can now safely house very toxic waste. This is because the resulting contained landfill cannot leach through the impermeable barrier into the groundwater. Many potential sites, such as old quarries, are dismissed out of hand as unsuitable for waste treatment as they have very steep walls. However, landfill designers and engineers looking for practical solutions for landfill lining find that DAC is very stable on slopes, even those as steep as 34º, which means even sites with very steep walls can be used for landfill.