Risk Assessment of Small Landfills: A Case Study in Hai Phong City, Vietnam

Landfills are a common method for solid waste management in developing countries. However, unsanitary landfills can significantly impact the environment and human health. In this study, basic properties of twenty — three small landfills in Hai Phong City (Vietnam) were identified, and the E-RAMP model was used to assess their risks. The study results show that 100 % and 96 % of the landfills have a high impact on surface water and groundwater environments, respectively. The impact on air quality, fire hazard, and greenhouse gas emission is very low. Therefore, city authorities need to implement measures to manage water pollution from these landfills to mitigate the impact on water use activities in the study area.

Keywords: small landfills, risk assessment, E-RAMP model.

Introduction

Landfills are a common method for managing and disposing of solid waste. While they are essential for waste management, landfills can have significant adverse effects on the environment and human health if not properly managed like open dumpsite (Siddiqua, 2022). Environmental impacts caused by open dumpsites/ landfills arise from leachate contamination methane emissions, and air pollution. Leachate can contain hazardous chemicals, heavy metals (Cu, Ni, Cd, Hg, …), and pathogens (Sabir et al., 2022). If not properly managed, leachate can contaminate groundwater and surface water, posing serious risks to ecosystems and human health (Wijekoon et al., 2022). Methane emissions from open dumpsites and other kind of landfills contribute significantly to global greenhouse gas emissions, accounting for approximately 10–12 % of anthropogenic methane emissions. Methane not only contributes to climate change but also poses explosion hazards if it accumulates in enclosed spaces (Górka et al., 2015). Open dumpsites emit various air pollutants, including volatile organic compounds (VOCs) and particulate matter. These pollutants can degrade air quality and cause respiratory issues, cardiovascular diseases, and other health problems. Wang et al. (2022) have demonstrated that open landfills significantly contribute to air and water pollution. Emissions from open landfills, including methane (CH ₄ ) and volatile organic compounds (VOCs), contribute to climate change and local air pollution. The leachate from these landfills contaminates groundwater, posing serious health risks to nearby communities. A study by Sharma and Singh (2021) highlighted the health risks associated with living near open landfills. Residents in proximity to these sites are at higher risk of respiratory problems, skin diseases, and other health issues due to exposure to hazardous pollutants. The study calls for immediate measures to manage waste more effectively and protect public health.

Understanding these impacts and applying appropriate risk assessment methods are crucial for mitigating the negative consequences of open landfill. Recently, there has been numbers of studies related to risks of landfills (Abunama et al., 2021; Etea et al., 2021; Iqbal et al., 2021; Swati et al., 2017; Wijekoon et al., 2022). The New South Wales Environmental Protection Authority (Australia) developed the E-RAM Model (Environmental Risk Assessment Model) which considers risks associated with small landfills in seven categories of environmental vulnerabilities, namely air quality, ground water quality, surface water quality, amenity, noise level, ecological conservation and cultural heritage (as a single category), and fire hazard (NSW EPA, 2023). Small waste facilities play an important role in local waste management. Operators (mainly local councils) manage the facilities and provide an essential service, often with limited budget and resources. The E-RAMP model helps these operators make general management decisions and improve their facilities' environmental performance by undertaking a risk assessment on operational small waste facilities.

In this study, the E-RAMP model was applied to assess the impacts on environment of 23 small landfills in Kien Thụy Commune, Hai Phong City, Vietnam. The findings aim to provide local authorities with critical information for managing the environmental impacts of these landfills and prioritizing resource allocation to address pollution issues effectively.

Materials and methods

Materials

Hai Phong is a major port city and the largest industrial and maritime center in northern Vietnam. The small, mostly unsanitary landfills are concentrated in Kien Thuy district, with 23 landfills, covering a total area of 54,770 m², an average depth of 1.9 m, and an average height of 1.4 m. All of these landfills receive household waste from rural areas, and are located close to residential areas, rice fields, or aquaculture ponds, causing severe environmental pollution and significantly impacting surrounding economic and social activities. Some characteristics of these landfills are presented in Table 1.

Fig. 1. The study area and landfills

Methods

Site survey and data collection: The twenty-three landfills in this study have not been properly managed for a long period, resulting in limited information about them. To facilitate the assessment and classification of the risks associated with these landfills, the research team conducted a survey to collect information on their current status. The survey was conducted in November 2023. Additionally, the research team used Google Maps Pro software to verify or determine further details related to the landfill areas, and the distances from the landfills to the nearest residential areas. The collected information is presented in Table 1.

Risk assessment: The E-RAM Model has been applied in this study. Each risk factor is evaluated and scored based on specific criteria. E-RAMP risk calculations consider: 1) sensitivity of the surrounding environment; 2) types and quantities of wastes received, stored and disposed of at the facility; 3) presence or absence of management controls at the facility, and 4) measures to minimise the likelihood of emissions to the environment (NSW EPA, 2023). It does not compute an overall risk score for the site. The E-RAM model uses risk categories of “very low” and “very high” in addition to “low”, “medium” and “high”.

The data used to assess the risk of each landfill are presented in Table 1. The meteorological data applied uniformly to all 23 landfills are as follows: Annual rainfall: 1,600–1,800 mm, predominant wind direction: South-Southeast, average number of rainy days: 146.5 days per year, average humidity: 86 %-88 %, average wind speed: 13.9 kph.

Results and discussions

Landfill characteristics

The study results indicate that the total area of the 23 temporary landfills is 54,770 m². The smallest landfill area is 700 m², while the largest is 10,000 m². Most of the landfills are located near rice fields, embankment corridors, and many are near residential areas or aquaculture zones. One landfill is situated only 300 m from a residential area. All these landfills are 100 % filled and have ceased receiving waste. Most of them were closed in 2022. The landfill in Dong Xa Hamlet, Doan Xa Commune, has been closed for 10 years (since 2013). Some were closed between 2019 and 2021.

Regarding surface cover conditions, over 30 % of the landfills are exposed, while the rest are temporarily covered. Most of these landfills are not very deep (1–3.8 m) and have relatively low heights (0–3 m).

Table 1

Risk assessment of the landfills

The risk assessment results for the 23 landfills in Hai Phong City show that 100 % of these landfills pose a high risk of surface water pollution (Figure 2). For groundwater, 96 % of the landfills are at high risk, while the remaining 4 % are at medium risk. This is primarily due to the fact that most of these small landfills are located in low-lying delta areas, just a few hundred meters away from irrigation channels (see Table 1). These assessment results align with numerous studies on the impact of unsanitary landfills on water environments (Siddiqua, 2022; Wijekoon et al., 2022; Abunama et al., 2021; Etea et al., 2021; Iqbal et al., 2021; Swati et al., 2017). Unsanitary landfills, which often contain high organic content household waste, lack proper bottom liners, leading to leachate seeping directly into the soil environment of the landfill area, and leaking into both groundwater and surface water in the surrounding area.

With the exception of the significant impact on water sources, 100 % of the landfills studied pose a very low risk to air quality. The risks related to noise, fires, conservation, heritage, and greenhouse gas emissions are low or very low. These assessment results can be explained by the fact that most of the landfills are relatively small in scale (ranging from 700 to 1,000 m²), with an average waste layer thickness of 3.3 m. Moreover, these landfills are either open or have a cover of wild vegetation, leading to predominantly aerobic decomposition of organic waste, resulting in low CH ₄ emissions.

Fig. 2. Assessment risks of the landfills

Conclusions

In this study, we conducted a survey to identify several basic properties of 23 small, unsanitary landfills in Hai Phong City. Based on this data, the study assessed the risk of these landfills using the E-RAMP model. The results show that most of the landfills have a high impact on surface water and groundwater environments, while their impact on air quality, fires, and greenhouse gases is low. The findings indicate that Hai Phong city authorities need to focus on managing these landfills to mitigate their impact on water environments and related activities in the study area.

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