The Decommissioning of Landfill and the Management of Landfill Leachate: Dual Challenges of Environmental Protection
To further regulate and improve the management of decommissioning funds for hazardous waste facilities and sites, the Ministry of Finance, National Development and Reform Commission (NDRC), Ministry of Ecology and Environment (MEE), jointly issued a notification about Measures for the Advance Withdrawal and Management of Decommissioning Funds for Key Hazardous Waste Disposal Facilities and Sites. Aiming to efficiently prevent the environmental pollution risks caused by hazardous waste, protect the ecological environment, and safeguard human health, the measures have been officially implemented since 1st January 2022.
The landfill is the major non-hazardous treatment measure for hazardous waste, which plays an important role in preventing environmental pollution and protecting ecological environment. However, the output of hazardous waste in China is constantly increasing and so is the demand for landfill sites. From 2018 to 2020, the amount of landfill sites has risen from 82 to 148, while the output of hazardous water has increased from 835 tons to 1058 tons with an approximately 13 annual growth rate.
The data indicates that the demand for landfill construction will constantly increase. According to the research of the Chinese Research Academy of Environmental Sciences, it is found that the level of design, construction, and management of hazardous landfills is low. Consequently, the lifespan of these hazardous waste landfills is relatively short. Once the lifespan of the landfill expires, the function of the pollutants isolation barrier will decline dramatically. The risk of poisonous components leakage will also significantly increase, causing long-term environmental risks.
To solve this problem, it is necessary to implement a series of measures to extend the landfill’s lifespan and improve the risk control system. By improving the technology level of landfills, the goal of environmental protection can be achieved.
The lifespan of landfill refers to the period from its completion to the loss of its pollution isolation capacity, which is highly dependent on the lifespan of anti-seepage material, HDPE Film. According to foreign research, under the conditions of a complex environment and high-intensity stress-strain, the lifespan of HDPE Film fluctuates around 50-100 years, having a lot of limitations. In addition, hazardous waste contains harmful components such as heavy metals. These components are hard to degrade, causing long-term environmental risks. Once a landfill reaches the end of its lifespan, the rapid degradation of its anti-seepage materials will significantly increase the risk of hazardous components leakage, posing a severe threat to surrounding soil and groundwater environments.
To deal with this problem, the Ministry of Ecology and Environment (MEE) amended and released the “Pollution Control Standard for Hazardous Waste Landfill” (GB18598-2019) in 2019. This standard not only regulates the design, construction, quality assurance, and waste disposal requirement of landfill but also proposes the concept of lifespan design for the first time. What’s more, it specifies the secondary disposal of hazardous waste after the landfill decommissioning, preventing environmental risks caused by the decommissioning. Meanwhile, MEE has also organized a nationwide special rectification campaign for hazardous waste, focusing on inspecting and rectifying facilities such as landfill sites for hazardous waste treatment, and eliminating many potential safety hazards.
Despite such endeavours, research from the Chinese Research Academy of Environmental Sciences suggests that the lifespan of hazardous landfill in China is still relatively short. One of the reasons lie in the poor quality of engineering and construction. Some hazardous landfills use inferior HDPE Film, which is prone to damage and aging. What’s worse, the laying and installation of HDPE Film, and the quality control and assurance are lacking of regulations. The damage problem of HDPE Film is severe, with an average density of holes reaching 28 per million square meters. Another reason is the relatively low level of operation and management. In some landfills, the control of leachate is insufficient, resulting in large volumes, high concentrations and complex compositions of leachate. Some landfills directly bury reactive waste or waste salt with poor mechanical stability that is incompatible with HDPE Film, accelerating the aging of engineering materials such as HDPE Film.
In addition, the site selection of some landfills is flawed. Once their lifespan expires, environmental risks will increase rapidly. In some coastal provinces such as Jiangsu and Zhejiang, the bottom of landfills is below the groundwater level, or they are close to sensitive regions such as the sea and rivers. Once the manufactured anti-seepage loses efficiency, a high concentration of poisonous leachate will directly penetrate to the surrounding area and contaminate water, which causes severe environmental pollution. Apart from direct risks, there will be the difficulty of secondary disposal of the buried hazardous water after the lifespan of landfill expires. It dramatically increases the disposal volumes which might lead to insufficient capacity.
Another problem is that we are not clear about the lifespan of the landfills currently in service. There is a lack of technology capable of identifying and estimating the lifespan of landfills. Understanding these conditions is critical for formulating targeted risk prevention and control as well as emergency response plans in order to alleviate potential environmental pollution. Unfortunately, related enterprises seldom take the initiative to research and estimate the remaining lifespan of landfills. At the national level, no comprehensive investigation or assessment has ever been conducted. By far, the lifespan characteristics of approximately 150 commercial landfill facilities -- along with numerous privately owned on-site landfill -- remain unverified.
Meanwhile, related industries lack knowledge about lifespan of landfill and long-term environmental risks. Normally, they just bury the hazardous waste without any non-hazardous treatment. They have not allocated sufficient funding for R&D to control and manage the long-term risks posed by the hazardous waste landfill. Current research on lifespan prediction for hazardous waste landfills remains limited, with existing methodologies being largely undeveloped. This lack of robust prediction tools severely hampers effective risk prevent and control in landfill management. Furthermore, there is a notable deficiency in design optimization studies targeting landfill lifespan. This knowledge gap directly contributes to inadequate engineering design capabilities, poor construction quality, and underestimated lifespan.
As early as 2004, China’s Law on the Prevention and Control of Environmental Pollution by Solid Waste established two critical mechanisms: 1. post-closure pollution prevention requirements for key hazardous waste disposal facilities; 2. decommissioning fund escrow system, creating the legal framework for life-cycle risk management of landfills. However, the absence of implementing regulations and technical guidelines has rendered these provisions largely inoperative, with the mandated systems failing to achieve effective implementation. The revised 2020 edition of Law on the Prevention and Control of Environmental Pollution by Solid Waste strengthened these requirements.
To comprehensively implement the revised legal requirements, Measures for the Advance Withdrawal and Management of Decommissioning Fund for Hazardous Waste Landfills have established a foundational framework, mandating landfill operators’ primary responsibility for maintaining the landfill (30 years after closure). However, critical gaps persist in addressing long-term liabilities, including costs for secondary waste disposal and fees for repairing the contaminated site. The uncovered risks may ultimately default to public fiscal authorities.
In summary, to secure the environmental safety of hazardous waste landfill, it should formulate a comprehensive lifespan management and risk prevention and control plan. Stimulating technical innovation and enhancing supervision is critical for long-term operational stability and risk control.
