Introduction
The proper disposal of industrial waste is one of the major challenges facing environmental conservation as a central component of sustainable economic growth. In most cases, improper handling of industrial waste leads to extensive contamination of landfills and other places that are exposed to such materials. Therefore, when such contaminations occur, urgent remediation measures should be taken to address the problem and prevent the exacerbation of the issue and long-term negative effects. This paper discusses one such contaminated area – the Tullamarine landfill on Western Avenue, Westmeadows, Australia. The paper explores how the site was contaminated, the resulting problems, remediation methods used to address the problem, the success of the remedies, and alternative treatments that could have been used.
How the Site was Contaminated
Before 1971, the Tullamarine landfill operated as a quarry. However, in 1972, the Shire of Bulla issued a certificate of registration to the Industrial Waste Collection (VIC) Pty Ltd for the quarry to be converted into a landfill for the disposal of industrial waste (EPA Victoria 2016). Only solid and liquid waste would be allowed into the landfill, and thus domestic garbage was excluded. Waste disposal started in 1972 in mound 1, which was placed at the eastern end of the main quarry before progressive to mound 2 (at the northern part) (EPA Victoria 2016). The waste, both solid and liquid, was placed in craters, and excess liquid would be collected at the bottom of the waste pile. Leachates collection sumps, with large diameters, were installed to recover any liquid that could escape the system. In 1976, a layer of clay lining, approximately 1 meter thick, was added to the wall, especially across the more permeable Brighton Group sediments.
However, these measures were not stringent enough to prevent the contamination of the land surrounding the landfill, especially given the nature of materials that were disposed of at Tullamarine. According to EPA Victoria (2016), over 70 percent of Victoria’s oil-based liquid wastes were dumped at the landfill up until 1987. The large volumes of liquid wastes could not be contained in the landfill, and thus leaching led to the contamination of groundwater in the area. In 1987, the Victorian government banned the disposal of liquid waste into the landfill as a countermeasure. However, the damage had been done as people living around 200 meters from the site were reportedly having higher cancer incidence rates than the national average. Therefore, the area was contaminated through the leaching of excess oil-based liquid waste because the clay lining and leachate sumps installed could not accommodate the volumes of waste dumped at the Tullamarine landfill.
Problems Caused by the Contamination
The major problem caused by the excess dumping of oil-based liquid wastes and other solid wastes was the contamination of the underground water. According to a 2007 audit report on the site,
The co-disposal of liquid prescribed industrial wastes between 1972 and 1987, the operation of the liquid waste treatment plant between 1988 and 1991, and the oil recovery plant between the early 1980s and 1987, a wide range of inorganic and organic contaminants were identified in the landfill and surrounding areas in light non-aqueous phase liquid (LNAPL), leachate, and groundwater (Environmental Audit Report 2007, p. 4).
Consequently, people using the contaminated water experienced adverse health effects. Residents living near the site commissioned their own study into the effects of the landfill on human life.
The Western Region Environment Centre conducted the study and found out that people living around the place had higher cancer incidence rates of up to four times as compared to that of their counterparts residing in other areas in Melbourne (Caldwell 2010; Karahalios, Thursfield & Giles 2011). After the realization groundwater in the region was contaminated, all forms of usage were banned. Consequently, the livelihoods of people depending on this important source of water were affected adversely. As such, it suffices to argue that the contamination affected groundwater in the area leading to increased cancer incidence rates among the residents of Tullamarine and water scarcity in the area because the available one was unfit for human consumption.
Remediation Methods Used
Following the allegations that the Tullamarine landfill was becoming unsafe for the environment and human life, the company that owns it, Transpacific Industries Pty Ltd (TPI), created an elaborate plan to remediate the problem. The plan was divided into five areas – groundwater quality management, liquid waste management, landfill gas management, ambient air management, and landfill cap management.
Groundwater Quality Management Plan (GQMP)
The GQMP is a set of actions taken to manage and monitor both surface and underground water in the Tullamarine landfill. In a bid to meet the expectations of the affected communities and EPA, a comprehensive network of groundwater monitoring wells was drilled to monitor the extent of contamination and create a filtration system to address the problem. Both upper and lower monitoring wells were created for this purpose. One good example of such wells is the Werribee Formation Equivalents, which consists of “variable fluvial quartz sands, minor gravels, silts, and clays” (Kleinfelder 2016, p. 25). Administrative controls were also established to restrict the usage of groundwater in the area.
Liquid Waste Management Plan (LWMP)
At the time when the Tullamarine quarry was being transformed into a landfill in 1972, the technology and policy to have engineered integrated base and side linings to limit leaching were not available. Therefore, the landfill lacks a baseliner, which explains why extensive leaching was reported later during its operations. Therefore, the only way to manage liquid waste at this point is through extensive monitoring to ensure timely and continuous reporting of the situation for the necessary measures to be taken.
Landfill Cap Management
In 1989, the landfill was partly capped and modified to full capping in 2010 to improve rehabilitation and ensure long-term management. The purpose of the cap is to prevent rainwater from entering the landfill when it rains. When such water enters the landfill, it mixes with the available waste to form leachate, which ultimately escapes into the underground water system, thus causing contamination. According to EPA Victoria (2016), the current cap has a depth of 160 centimeters, and it is lined with a special membrane to ensure only minimal rainwater can enter the landfill. Additionally, the cap controls the amount of methane and other gases from the landfill by ensuring that they are burnt before escaping into the atmosphere.
Landfill Gas Management
Landfill gas (LFG) is mainly generated after the breakdown of organic waste materials. The common gases include methane and carbon dioxide. Therefore, in a bid to avoid air pollution from such gases emitted from the landfill, a management system was installed beneath the cap. The system is made of specially designed LFG collection blankets, which are used to direct the gases to a central point within each mound (Transpacific Cleanaway Pty Ltd 2010). A landfill gas flare was installed to burn the gases and convert them into less harmful gases before being released into the atmosphere. Additionally, perimeter gas migration monitoring wells were installed to ensure that gases do not escape the facility before being treated.
Ambient Air Management
Ambient air in this context refers to the air above the ground environment extending from the site to the neighboring areas. A risk assessment was undertaken to establish the impact of emissions from the landfill on the ambient air quality in the area. This part of management is concerned with ensuring the integrity of the landfill gas flare and the surface of the cap. Tests are conducted biannually, and routine checks are carried out monthly to ensure the necessary actions, such as repairs, are taken as a way of ensuring that harmful gases do not escape into the atmosphere.
The success of the Remediation Methods
The remediation methods used at the landfill have been successful so far. The owner of the landfill, Transpacific Cleanaway Pty Ltd, has come up with an elaborate post-closure management plan to ensure that all the set objectives are met. The necessary actions are taken and modified according to any arising needs for the maintenance of the integrity of the system. For instance, in 2011, the company committed to carrying out regular internal audits to ensure that it operated in accordance with the EPA’s Pollution Abatement Notice for the closed landfill (Golder Associates 2011). As such, with continued review and monitoring, the remediation methods have been effective and successful.
Alternative Treatments
One of the alternative ways that could have been used in this case is the construction of a leachate extraction well field. According to Beaven, Cox, and Powrie (2007), such wells support the removal and treatment of LNAPL. Additionally, the available toxins in the landfill could have been drained using pipes and discharged into a sewer system for incineration or conversion to fertilizers. Biological treatment is also another option for dealing with leachates from the landfill. Zhang et al. (2017) argue that biological treatment of leachate involves different filters to remove any organic compounds from wastewater. Wet-oxidation could also be used to oxidize organic compounds as a way of making the landfill safer for the environment and the surrounding communities (Amadi, Okeke & Amadi 2017). Nevertheless, it would be difficult to contain the leaching problem given that the landfill lacks a baseliner. Therefore, continuous monitoring of the extent of chemicals getting into the groundwater would be paramount to ensure that people are advised accordingly to take protective measures.
Conclusion
The Tullamarine landfill, even though it has been closed, continues to cause environmental challenges due to the extensive contamination of underground water in the area. During the construction of the landfill, a baseliner was not installed, and this scenario allows the leaking of chemicals into the groundwater, hence contamination. Different successful measures have been taken to address the problem. For instance, a land cap has been installed to prevent rainwater from entering the landfill when it rains. However, alternative methods such as biological treatment could have been used to address the problem at the site.
Reference List
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