Planning and managing landfills for sustainability | Infrastructure news

Although there is a growing trend in reducing the volume of waste produced – as well as the alternative use of waste as a measure to reduce the need for landfill space – municipal landfills will still be required for years to come.

KZN Dalton landfill-sugar cane rehab

KZN Dalton landfill-sugar cane rehab

However, most municipalities are finding it harder to identify suitable land for the development of these landfills. For a start, locations for landfills can only be considered feasible if there is geotechnical stability, and if current and potential future land-use allows; there are also issues of environmental sensitivity, social impact, health and safety, and economic feasibility to consider.

The landfill design capacity and lifespan will be determined by the areas serviced, while making allowance for the future growth of these areas. In recent years, there have been increasing reports of issues at landfills, ranging from nuisance issues and environmental impacts, to human health being adversely affected due to landfills being located too close to populated areas.

During planning, rigorous processes are undertaken to identify exogenous factors that may influence landfill location and lifespan; however, these are often driven by social factors that are difficult to predict. The result is that the rate at which the social structure changes may not have been considered during landfill planning, and may only become relevant years later. It is, therefore, important to ensure that landfills are designed and operated in a responsible and sustainable manner – with an eye on future population growth trends.

Regular monitoring

Mashie golf course in Wartburg constructed on a rehabilitation landfill

Mashie golf course in Wartburg constructed on a rehabilitation landfill

Aspects that enhance sustainable landfill operation include regular environmental monitoring for leachate and landfill gases and odours in accordance with strict standards, as well as continuously updating stakeholders on the landfill’s performance and plans; it is vital to conduct regular health and safety inspections, and ground stability and
integrity checks. It is also important to ensure that only waste compatible with the landfill classification is accepted for disposal.

It is necessary to anticipate the closure and rehabilitation of the landfill during the planning and design phases; a predetermined post-landfill land-use can generally be determined when a landfill is designed, facilitating a closure model suited for the intended post-closure land-use and allowing the facility to be operated with this intended use
in mind.

By implementing measures during operations that help achieve final land-use, the rehabilitation efforts necessary at the end of life can be reduced. This limits any potential negative legacies left behind by improperly closed landfills, and achieves the planned post-closure land-use more rapidly.

Finally, operational implementation of measures towards closure – combined with the implementation of final closure measures – limits the potential for latent risks and liabilities to arise later. These might require the stabilising of waste to limit future settlement, or the isolation of waste from humans and environmental receptors – including water resources. This needs to take cognisance of reasonable future land-use scenarios, particularly the increased demand on groundwater resources that may have previously been considered of insufficient quality.

This often requires the adequate compaction of the waste body and the construction of appropriate barriers over the waste material. Ongoing, regular and appropriate monitoring is then required to detect possible risks or impacts before these become significant.

NWP Municipal Landfill

NWP Municipal Landfill

Sustainable land-use

There are several innovative examples of landfills being transformed into sustainable post-landfill uses, and SRK has been involved with municipalities in a number of these. A crucial ingredient to success is adequate waste management planning, which ensures that landfills can be closed without having to attend to other issues related to poor waste management practices.

In one project, SRK compiled an Integrated Waste Management Plan (IWMP) for uMgungundlovu District Municipality in KwaZulu-Natal, and then managed the implementation of the plan in each of the seven local municipalities over a period of three years.

The implementation process comprised various elements, from the creation of a waste information system and waste minimisation pilot projects for industry, to waste recycling projects. Work included database design, capacity-building, awareness training, landfill training for operators, landfill auditing and landfill closure. There was also the need to rehabilitate waste disposal facilities, as well as identify and develop new ones.

To guide the process towards obtaining compliance for waste facilities within the district municipality, a steering committee made up of key stakeholders was formed in each local municipality. In one of these local municipalities – uMshwathi – three historical domestic landfill sites required closure permitting.

KZN New Hanover landfill-community sports field

KZN New Hanover landfill-community sports field

For two of the sites, SRK undertook the closure design and permitting, and also managed the closure contracts. Based on consultation with the surrounding communities and landowners, one landfill was transformed into a community sports field, while another was rehabilitated to be returned to its pre-landfill use – sugarcane cultivation – to maximise the land’s potential. The third landfill was converted into a mashie golf course, complete with aesthetically pleasing wetland areas.

The quality of this work was based on SRK’s extensive experience in the assessment of potentially contaminated land, and in facilitating its redevelopment to alternative land-use. “SRK has established itself as one of the leaders in the full life cycle of waste management and landfill design over the years, serving industry and various levels of government.”

In 2004, SRK compiled the IWMP for the North West and, in 2005, assisted with Gauteng’s Waste Management Policy. In 2011 and 2012, SRK developed the Integrated Hazardous Waste Management Plan for KwaZulu- Natal and, in 2018, compiled the Waste Management Chapter for the Western Cape’s ‘State of the Environment’ report.

The company has also undertaken numerous landfill designs and is involved with environmental monitoring – focused on water and air quality – as well as the licensing and auditing of landfills in private developments, local municipalities and on a regional scale.

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