Stabilization in Landfills with Changing Waste Streams

No two landfills are alike. The composition of the waste being dumped at each landfill differentiates each location. The waste stream is like the DNA of every landfill and depends largely on the types of waste being dumped. While engineers can plan ahead to create a landfill with sufficient containment and slope stabilization to meet the trash requirements of the local population, evolving economics can significantly alter the trash composition. A changing waste stream can go on to affect landfill stability, leachate quality, and gas collection. Together, these changes can raise maintenance requirements and even pose a risk to containment.

In this article, you’ll learn how a changing waste stream can affect slope stabilization in landfills. You will also learn how these changes can affect maintenance requirements and how you should reevaluate landfill stability to account for the changing waste stream.

How the waste stream calculation changes over time

Landfills’ waste streams change constantly. In many ways, the waste stream is a direct reflection of the country’s economic health. When we are living in times of plenty, our culture consumes goods and services at an insatiable rate, leading to large spikes in municipal solid waste (MSW) production. Fortunately, our landfills are designed to handle this kind of waste with ease. The calculation is a matter of creating enough landfills to support all the waste.

But when we are living in times of shortage, society cuts back on consumption and MSW decreases. Surprisingly, this poses a problem because, unlike MSW, the elements making up industrial and mining waste produces byproducts that can affect the composition of the waste stream. These byproducts can go on to affect the landfill’s slope stability, especially if there isn’t enough MSW in the waste stream to absorb moisture thus help solidify the mass. Furthermore, some of the byproducts can necessitate pretreatment or even on-site treatment to prevent overly corrosive or damaging leachate from being produced that could negatively affect waste water treatment plant operations.

During the 2008 recession, the proportion of MSW to industrial waste shifted significantly. When industrial waste makes up 5% of the total landfill contents, the effects are negligible. The same can’t be said when industrial waste makes up more than a quarter of the landfill mass. At that stage, landfill stability, gas production, and leachate quality all become important maintenance concerns.

Minimizing the impact of industrial and organic waste

As waste volumes declined, waste management companies sought to replace those volumes with other materials such as industrial waste, including wet waste sludges and drilling muds. Those materials require use of solidifying agents, to lessen the impact on landfill stability and reduce leachate production. In many cases, landfill operators have to upgrade or modify existing leachate collection systems to be able to handle the increased load.

Even with organic waste diversion efforts, food waste content in the waste stream has increased. These waste materials will affect landfill gas generation and leachate generation.

Landfills designed for a changing waste stream

Given the potential issues of a wetter and gaseous waste mass, proactive use of geomembrane liners by designers can reduce rainfall infiltration and control landfill gas emissions. By using the right combination of geomembranes and drain liners, designers can create a containment system capable of dealing with almost any kind of waste stream.