Hooge Maey has opted for an extensive remediation project with a consistent focus on quality and sustainability. This will ensure that the effects of the landfill site on the environment will be negligible.
The remediation is being carried out using a combination of techniques. The site covers an area of more than 100 hectares and has been divided into zones. Each zone has its own specific remediation approach. A conscious choice has been made to use the best techniques available.
The remediation plan was based on a thorough risk analysis. In this context the impact of the landfill site on soil, air and water was measured. To do this the most advanced techniques were used:
- The effect of the landfill site on groundwater was examined using tracers, such as the genetic fingerprint of bacteria and the presence of the tritium ion in the landfill and groundwater
- Detection of water by means of electromagnetic probing
- Installation of a test flare in order to determine the quantity and quality of the landfill gas - Creating test plots to implement the best system for the isolation of polluted sites
- Setting up pilot installations to determine the most effective method of water purification
Hooge Maey has been divided into separate zones, which depending on their zone-specific properties have had different forms of remediation.
- In Zone A, highly localised pollution was found consisting of industrial sludge and tar. This zone used to serve as a landfill site for industrial and household waste. This zone is no longer operational. The waste has been fully excavated and treated elsewhere. Today there is a buffer basin with a reed bed.
- The rainwater from zone B is discharged through this zone towards the waterway 'Schijn.' Zone B was used as a landfill site for industrial and household waste for 20 years. In order to make sure that the waste that is still present there can no longer have any environmental impact, this zone has been isolated. Today this remediated zone is again used as a landfill area.
- Zone C is the central, highest 'waste mountain'. Right up until 16 July 2009 this zone was used for landfilling. In 2012 the final capping of the hill was completed.
- In Zone D the remediation work has been limited. Part of the zone was conceded to a company that produces the material necessary for the final capping ('Hydrostab') and to a company that recycles construction and demolition waste.
Between 1999 and 2012 the following work was performed within the scope of the remediation project:
- Accurate monitoring of the groundwater quality
- Purification of the waste water (leachate) in an on-site water treatment unit
- Channelling and recovery of methane
- Recovery of landfill gas in a gas engine with conversion into electricity
- Encouraging waste inertisation
- Isolating the landfill site from the surroundings (final capping, drainage systems, ...)
- Stabilising the landfill by remodelling the banks
- Integration of the landfill site into its surroundings by redefining its destination