In the State of New South Wales there are more than 400 landfill waste disposal sites, most of which do not incorporate measures for the collection and treatment of landfill gas. This includes many old or closed landfill sites, rural and regional landfill sites, non-putrescible solid waste and inert waste landfill sites. At many of these sites landfill gas is emitted uncontrolled into the environment where it contributes to the greenhouse effect and at some sites presents health and safety risks.

A primary factor in the limited implementation of measures to capture and treat landfill gas is the high capital and ongoing operating costs of conventional active gas extraction and flaring systems. Typically such systems are only installed at large landfill sites and at sites where landfill gas emissions present a hazard or are migrating off site.

Passive drainage and biofiltration of landfill gas is a new approach to landfill gas management that may provide a cost effective means of reducing landfill gas emissions at low to moderate gas generating landfill sites. The approach utilises passive methods to direct landfill gas to a dedicated biofilter(s) and uses naturally occurring micro-organisms to oxidise the methane in the landfill gas.

Stuart's presentation provides an outline of the research undertaken by University of NSW, GHD, and PSM over the past 3.5 years, including the latest findings, which show that passive landfill gas drainage and biofiltration systems can effectively capture and treat landfill gas. The success of research has lead to the construction of a full-scale passive landfill gas drainage and biofiltration system at a landfill site in Sydney.

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On October 24 2006,  the NSW Landfill Working Group organised a breakfast seminar on groundwater monitoring.

The NSW Department of Environment and Conservation recently commissioned Ian Grey Groundwater Consulting (IGGC) to undertake a technical review of groundwater monitoring networks, programs and data for ten Sydney basin landfill sites. The sites included in the study covered a range of geological settings, waste types, design and age.

Groundwater monitoring is an integral component of landfill management. Landfill operators need to ensure that groundwater monitoring networks are able to detect changes in groundwater chemistry and provide ongoing understanding of site conditions.
The technical review highlighted the need for effective interpretation of groundwater and leachate monitoring data by landfill operators based on a sound understanding of groundwater flow regimes, the potential for leachate migration, hydrochemistry of leachate migration and historical conditions. The presentation outlines the findings of the review focussing on groundwater and leachate monitoring requirements and common inadequacies in monitoring for the sites studied. Important factors to consider in the design of monitoring networks, sampling protocols, QA/QC and bore maintenance will also be discussed.

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• Waste Regulatory Reforms - Protection of the Environment Operations Act & Regulations: Jane Mallen-Cooper 2.8.05 
  
• Passive Drainage Biofiltration of Landfill Gas: Stuart Dever 6.6.06
  
• Erosion & Sediment Control on Landfill Sites: Dr Steve Perrin 22.3.05