The Situation
The onset of recession, rises in the rate of landfill tax and an increase in the subsequent promotion of recycling activities in recent years has resulted in lowering demand for landfill. Consequently the constructed ‘void’ at Wapseys Wood landfill is taking longer to fill than originally planned. Indeed, the planned closure date for the site (2012) has already been extended by 5 years to enable the site to be completed to an appropriate landform. Additionally, we closed our Springfield landfill site in order to divert waste and minimise this impact at Wapseys Wood.
These actions hindered installation of landfill gas collection infrastructure, placement of engineered capping and restoration soils progressively across the site. We reacted by modifying our operational techniques and site engineering principles to accommodate this changing situation.
Actions
As a further consequence of this situation and the increased rainfall over recent months, accelerated landfill gas production is taking place and we have undertaken the following actions:
- Placing waste in modified locations to facilitate earlier installation of landfill gas control systems;
- Installation of temporary gas extraction infrastructure earlier than would otherwise have been possible;
- Redesign of gas collection wells to increase efficiency;
- Increase in removal of leachate;
- Substantial upgrading of the power generation plant and carrier mains;
- Increased capital investment in environmental control;
- Increased environmental monitoring.
- More specifically, since November 2013 works have included:
- Installation of 58 gas extraction wells;
- In excess of 2,000 metres of gas collection pipes laid;
- Placement of 40,000m2 of permanent capping and restoration soils;
- Redesigned surface water management system;
- Modified landfill sequencing to expedite installation of gas extraction wells.
In addition we have planned future works to prevent further releases of odour from the site, to include:
- Accelerated completion of the current operational area to allow installation of around 10 gas collection wells during February (originally due in July)
- Redesign of the landfilling in the current engineered phase to enable completion by March (3 months early) allowing the placement of approx 40,000m2 of permanent capping and restoration soils; and earlier installation of around 40 gas extraction wells.
- An additional proposal is the installation of approximately 40,000m2 of welded polyethylene liner on all previously landfilled waste flanks at the site.
The benefits include significantly improved sealing of landfill slopes; effective control of odour; enhanced landfill gas control system; enhanced leachate control; and improved rainwater management.
These works will commence in February with completion by the end of March.
We are confident that the works detailed above will enable us to carry out our operations and undertakings at the site and resolve the current issues being experienced locally.