1. Landfilling (Containment and Restoration) in Ireland
Nigel Ruxton

2. Background and Context
Chartered Professional Engineer (CEng MIEI CPEng MIEAust RPEQ)
Worked for an engineering consultancy in Ireland in the area of waste management since 2003
Senior Civil Engineer for Golder Associates in Brisbane (Dec 2011)
Difference in level of regulation and design criteria between Australia and Ireland
Presentation is based on personal experience and is not intended to provide a comprehensive or general overview of landfilling practices in Ireland
January 13, 2019

3. Regulatory Requirements
January 13, 2019

4. General Regulatory Requirements Design Stage
EU Landfill Directive (Directive 99/31/EC) lead to legislation
Regulators – Environmental Protection Agency (EPA) and Northern Ireland Environment Agency (NIEA) enforce legislation
Waste Licences set out regulatory requirements for landfill sites
Requirement to produce a Specified Engineering Works (SEW) or Construction Quality Assurance (CQA) Plan
Regulator undertakes review and provides feedback
January 13, 2019

5. Sample feedback from Regulator
Adequate control of landfill gas
Installation of landfill gas collection pipework
Placement of geosynthetic layers and soils
Testing of cover soils
Independent CQA Supervision
CQA File (as per Waste Licence)
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6. Typical Landfill Design
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7. Typical Waste Containment Systems
Standard System
GW Layer
Bentonite Enhanced
Soil (BES) or Clay
HDPE
Geotextile (1500g/m2)
Geocomposite/Gravel
Leachate pipework
Piggyback System
Gas Collection Layer
Clay (500mm)*
GCL
LLDPE
Geotextile
Geocomposite drain
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8. Typical Capping System
Regulating layer
Geocomposite Gas Collection Layer
GCL
Geocomposite Surface Water Drainage layer
Geogrid (if applicable)
Subsoil
Topsoil
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9. Typical Problems and Controls
Sourcing natural materials
BES instead of Clay
Crushed stone instead of gravel
Geocomposite drainage layers instead of drainage stone
Subsoil & Topsoil ???
Leachate and Gas controls
Leachate toe drains
Gas cut off trenches
Active Gas Extraction
Bentonite slurry walls
‘Piggyback’ landfills
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10. Site A – Northern Ireland
42 Hectares
Reclaimed land
Landfill gas to
Energy
Leachate treatment
to Biomass
Revenue streams
for Council
Potential Town
Park
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11. Site B – Republic of Ireland
Circa 9 Hectares
36,000 tonne per annum
Historic and Engineered landfilling
Active Gas Extraction and Flaring
Leachate Treatment – potential for Biomass
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12. Operational Issues
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13. Landfill Gas Collection
Landfill gas – resource or nuisance?
Vertical wells
Horizontal drains
Perimeter drains
Rodding eyes
Built-up wells
Temporary caps
FID Monitoring
Maintenance
Flaring & power generation
Built-up well
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14. Leachate Management Three Main Options Haul to WWTW
On site treatment and haul to WWTW
Full on site treatment and discharge
High cost of hauling and requirement to treat leachate first
On site treatment can include settlement and aeration
Reed beds/Wetlands
Short Rotation Coppice (willow/poplar) being considered by Regulators
Leachate used as fertiliser for willow/poplar to produce Biomass
Early capping reduces leachate generation and can cover restoration costs
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15. Review of Operational Procedures
To ensure compliance with Waste Licence
To reduce restoration and aftercare costs
Filling plans
Daily cover material
Landfill gas extraction system
Leachate pumping systems
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16. Summary EU Landfill Directives ensure high levels of regulation
Containment and restoration options can still vary from site to site
Important to engage with Regulator to control construction cost
Landfill gas can be a resource or a nuisance
Leachate management costs increase if capping is delayed
Operational improvements can reduce operational, restoration and aftercare costs
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17. QUESTIONS? nruxton@golder.com.au
THANK YOU
QUESTIONS?
January 13, 2019