The Cottonmount Landfill Site is located in Mallusk, County Antrim in Northern Ireland, just outside Belfast. The site is located within Cottonmount Quarry, a working hard rock quarry, which receives municipal waste from Belfast City. WALO was appointed to construct three landfill cells using its Dense Asphaltic Concrete (DAC).

Given the proximity of the site to residential areas and to underground aquifers, it was of paramount importance that the landfill cells were constructed with an extremely strong lining that would remain impermeable to leachate or methane from the waste. The works had to be undertaken during extremely challenging weather conditions in the depths of winter. WALO’s DAC is highly robust and impermeable so is ideal for complete containment of all materials that need to be impounded such as landfill. It is also very quick to lay, making it the perfect solution for a project like this which had to be carried out within a limited time frame in very wintry conditions.

WALO constructed the cells as part of a composite lining system of some 17,800m² using DAC formulated in the company’s Zurich laboratory to a design mix unique to the project. The lining system comprised a 300mm mineral attenuation layer; 200 mm sub-base material layer; 60mm asphaltic binder layer, 80mm dense asphaltic concrete layer and a mastic seal coat to the base, side slopes and bund areas. The works involved the placing of asphalt by paver and winch on a 40m slope. Once the lining was completed, a 300mm thick layer of leachate drainage stone was applied to the whole area.