IWWG Experts forum on


Contact: Stephanie Bolyard and Dongbei Yue



The task group "Sustainable Landfilling" was founded on June 2005 in Montegrotto, Italy, following the decision of the Scientific Advisory Committee of IWWG at the Lake Toya meeting on Hokkaido, Japan (ICLRS, 2004). The Sustainable Landfilling task group has been founded in order to co-ordinate interdisciplinary research on sustainable landfilling, discuss and disseminate related results, and to provide scientific support for modern regulations. In October 2011 the task group decided to adopt a new name: Sustainable Landfill Management

Aims and Objectives

During a workshop in October 2009 it was concluded that the landfill industry and the regulators need a definition in order to agree on certificates of completion more than a definition of sustainable landfill. Considering various issues the workshop reached consensus on the following definition of acceptable risk for landfills in the context of aftercare completion:

  1. The landfill reaches functional stability (based on site-specific physical, chemical, and biological characteristics of the waste mass and its location) such   that the landfill, taking into account its proposed after-use, is unlikely to pose an unacceptable risk to human health or the environment;
  2. During the process towards stability no unacceptable risk should occur;
  3. This situation should be reached as quickly as possible and within the financial provision time;
  4. The funding for completion of aftercare has been secured and allows for appropriate after-use of the site with minimal (custodial) care.

During a task group meeting in October 2014 a position paper on Terminology for Landfill Aftercare Completion and ‘de minimis’ Care was adopted. The purpose of aftercare is to manage the threat posed by a closed landfill to human health and the environment. This is achieved through active care activities comprising operation, maintenance, and monitoring. In order to end aftercare, therefore, it will be essential to demonstrate that the landfill poses no threat to HHE in the absence of active care. Independent of whether the demonstration is based on a site-specific approach or on more general limit values, a risk-based approach is preferred. While the level of care required for protection of HHE can be expected to decrease with time, some level of care will likely be required for the long term at most landfills. Whether this care is considered to be ‘de minimis’ care or active aftercare and whether this care is provided under an aftercare permit or under a new covenant will be a function of site-specific conditions, the perceptions of the owner and governing authority, the national regulations in terms of environmental liability, and the financial resources that are available or that can be generated from appropriate beneficial reuse of the land.

In its ongoing work, the task group aims to collate research results on:

  • The criteria for landfill aftercare completion;
  • The operational controls/measures to achieve sustainable landfill management, including: the waste acceptance criteria necessary; and the accelerated physical, chemical and biological stabilisation techniques required and the optimum time for their application.

The task group will cooperate with other groups (especially CLEAR and Landfill Aeration) to achieve the above.

The task group will disseminate its findings:

  • In the Journal, Waste Management;
  • In monographs or other special publications;
  • At IWWG meetings and those of organisations collaborating with the group.

Work in progress

The work on relevant questions for a completion procedure (what do we need to know, what information do we need to answer the question) has been finalised. Based on these questions a draft framework for completion procedures has been developed. Aftercare completion guidance could entail different elements with increasing level of detail:

  • A framework for assessment;
  • Aspects to be assessed;
  • Indicators for the aspects;
  • Criteria for the indicators.

The next steps in the work of the task group will be to give further detail to the draft framework and to promote application and compile experience by means of case studies.


The task group members include academic and industrial researchers and scientists from different countries:

André van Zomeren

Energy Research Centre


Anna Åkerman Suez Environment FR

Debra Reinhart

University of Central Florida


Dongbei Yue Tsinghua University CN
Emerance Bietlot Institut scientifique de service public BE

Heijo Scharff

NV Afvalzorg Holding


Jeremy Morris



Lale Andreas

Luleå University of Technology


Marion Crest

Suez Environment


Masato Yamada

National Institute of Environmental Studies


Morton Barlaz

North Carolina State University


Natalia Sliusar Perm National Research Polytechnic University RU
Ole Hjelmar DHI Water Environment Health DK

Olivier Bour



Roberto Raga

University of Padua


Stefanie Bolyard University of Central Florida USA

Timo Heimovaara

Technical University Delft


Tiziana Lai

University of Padua


Apart from the above members there is a large group of people (>35) following the work and occasionally contributing to the discussions.

TG Leader & Contact person:

Stephanie Bolyard
Environmental Research & Education Foundation (EREF)

E-mail: sbolyard(at)erefdn(dot)org

Next Task Group Workshop and Meeting:

October 2017, during Sardinia 2017, St. Margherita di Pula, Italy.


Workshop on 14 June 2016 in Noboribetsu Onsen, Hokkaido, Japan

The workshop consisted of two parts. In the first part the workshop focused on appropriate indicators. It was concluded that with respect to FTIR and humic substances characterisation there are still too many unknowns and uncertainties to use them as a proxy. It was however considered useful to continue working on these topics in order to increase our understanding. It would be extremely helpful if easy to analyse sum parameters could be used as indicators. Indicators will however be site-specific. Different landfill environments give different gradients. The site-specific processes that mobilise contaminants will provide the relevant indicators. Many supported that geochemical modelling based on toxicity data is probably the best way to describe threats to human health and the environment. It is however a very complicated approach.  

The second part of the workshop focused on the framework for assessment. SLM started addressing the issue by compiling questions a competent authority might want to have answered. Most important will be an assessment confirming that specific criteria are met. For such an assessment data quality is very important. In addition the competent authority might want reassurance that the stable situation at the moment of the assessment will not change in the far future. These three aspects were introduced and discussed separately.

Previous SLM work on relevant questions leading to an assessment framework was summarised:

  • A generic framework with a high level of abstraction is needed;
  • The framework is based on a step wise decrease in aftercare activities;
  • Decrease in aftercare is based on compliance with indicators for functional stability;
  • The ambition is to increase the certainty about current and future emissions of the landfill;
  • Details concerning aspects and indicators will be country and/or site specific;
  • The framework facilitates a joint learning journey for each site.

This outline seemed to broadly supported. In drafting a framework the workshop recommended to deal with differences in perception. It is also necessary to bring the information in understandable terms. The aspect of uncertainty has to be addressed. In some countries (financial) uncertainty is reduced by revising the required sum of money for aftercare every five years.  

Predictions on the future can be made by means of extrapolation. Extrapolation is a modelling approach without inclusion of process knowledge. An alternative modelling approach was presented. It combines fundamental generic behaviour of water flow, geochemistry and biology with stochastics to handle the remaining uncertainty. The workshop confirmed that this type of modelling would be worthwhile to further develop. It would be useful to validate the model with more datasets of different landfill environments. It was furthermore recommended to compare and possibly validate with natural analogies.

A couple of Dutch experiences were presented where data storage went wrong (flooding and fire in paper archives, inability to access floppy discs or old spreadsheet formats, design drawings being available but no as-built drawings, strange gaps and jumps in data sets that could not be explained reducing the credibility of the entire data set). For a competent authority decision the data need to be credible and reliable. The time between construction and ending aftercare requires information to be stored for several decades. The quality of the information from raw data to derived information needs to be traceable and reproducible (chain of custody). The workshop recognised the problems. The seriousness of having credible data was acknowledged. In general the recommendations were supported. The workshop considered it useful to draft a recommendation / position paper on data collection and data management.