The University of Southampton
Engineering and the Environment

Research project: How do we reduce the length of landfill aftercare?

Currently Active: 
Yes

Current landfills will require active management (Aftercare) for many centuries after they have been filled. How can this timescale be shortened to reduce the burden on future generations?

Project Overview

Background

Over the past ~20 years, an increasing awareness has developed that the downside of the impressive containment engineering now implemented at all landfills is that they have created timescales of at least centuries, and possibly millenia, before landfills will reach a point where no active management, monitoring, or inputs of energy or materials are needed, to control the release of contaminants from them.

These long timescales arise partly from the difficulty of achieving a sufficient degree of degradation of organic matter and partly from the very slow rate of flushing out leachate pollutants that results from low permeability capping.

Our research has investigated

1) the contaminant transport properties of waste that control the release and flushing of contaminants.

2) in situ aeration as a means to accelerate the degradation of organic material resistant to degradation in the anaerobic environment of the landfill

3)  The economics of landfill Aftercare, and possible Policy initiatives that could help shorten Aftercare periods

Borehole Tracer test

Landfill flushing

We have been developing new landfill characterisation tests to determine the contaminant transport properties of waste.  This has included research into the properties and behaviour of different tracers in landfills, including lithium, bromide, fluorescent dyes and deuterium.

We have undertaken investigations at a variety of scales, from the laboratory to the field where we have specialised in developing borehole characterisation tests.  Results have been interpreted within a variety of different contaminant transport models, including simple block geometry dual porosity models which can be readily applied to much of the data for saturated waste collected. The remaining research challenge is to adequately characterise contaminant transport in the unsaturated zone of landfills.

..installing instrumentation
In situ aeration trial

In situ aeration

Creating aerobic conditions in landfilled waste has the potential to stabilise closed and operational landfills, offering considerable long-term environmental benefits.  Aerating landfills may have a very important role in improving the sustainability of landfills: dramatically reducing the timescales for aftercare and the long-term pollution risk to the environment.

Our research reviewed the theory of air/ gas flow in drained waste materials and identified a theoretical framework that takes into account waste heterogeneity and composition. This was then incorporated into the established University of Southampton model for landfill degradation and transport (LDAT).  The model was applied to a series of coordinated short-term field trials that generated key data on efficient air distribution related to operational conditions on homogenised municipal waste.

Economics of Aftercare and Policy

Within the UK the responsibility for the Aftercare of (most) landfills lies with the operators, and will remain with them until the site has fully stabilised (taken to mean that in the absence of human intervention there is no further risk to human health and the environment from the site's presence).  Regulations require the operator to control emissions of landfill gas and leachate (contaminated water) to the wider environment, but do not require them to stabilise their sites within a set period of time.  As there are no financial incentives for operators to take the necessary remedial action to shorten Aftercare periods, we have been undertaking work to suggest new Policy initiatives that could utilise Landfill Tax to unlock the current impasse.

Related research groups

Infrastructure Group
Waste Management
to determine its contaminant transport properties
Tracer tests on waste
Installing test wells
Fluorescence Tracers
Field work
showing progressively cleaner leachate over time
Results of a flushing trial
Aeration trial
to increase degradation rates
Irrigating during aeration

Publications

Key Publication

Articles

Conferences

Staff

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