As part of the greater Warnervale residential development, the former Central Coast Council owned landfill was remediated and developed as a public recreation area. The site was used for quarrying and landfilling for approximately 20 years between 1969 and 1989.
Landfilled materials comprised primarily soils, construction debris and vegetation, as well as asbestos-containing-materials (ACM). Given the site was not secured and filling was not well controlled, other wastes including commercial and industrial wastes were disposed of.The presence of uncontrolled landfill waste at the site presented several hazards, predominantly landfill gas and asbestos containing materials. The closed landfill required substantial remediation along with capping to satisfy its new land use.
The construction of a third party EPA Auditor approved landfill capping system encountered hurdles in sourcing. Originally a low permeability clay capping system was specified as part of the approved design. Due to the lack of availability the introduction of a Geosythentic Clay Liner was suggested by Synergy and ultimately adopted. During landfill reprofiling an additional 8,000m3 of unconsolidated landfill was identified. The management of this material triggered additional import volumes for the overlying cap. A new profile design was required to meet the specifications.
Synergy successfully installed a landfill gas collection system, including horizontal collection trenches, vertical collection boreholes and vents in potentially hazardous conditions requiring strict adherence to stringent safety controls. Works were completed with the importation and installation of a revegetation layer, incorporating subsoil and topsoil layers and a turf vegetative cover to complete the final layer of the green space.Play Video