Waste management a critical part of any big demolition project

26 August 2020 | Web Article Number: ME202020274

Construction, Civil & Structural Engineering
Environmental Management & Control
Materials Handling & Bulk Handling
Waste management a critical part of any big demolition project

THE South African construction industry is under enormous pressure due to reduced margins and rising costs, especially due to limited operations as a result of the COVID-19 lockdown. While detailed planning for new construction projects is fairly common, the same level of care is often not applied to the demolition phases.

That’s according to Jet Demolition Contracts Manager Kate Bester, who said the expectation is often to conclude demolition quickly and cheaply, without much regard for the end use of the demolished materials.

“Achieving a fully compliant site is perceived as an ideal that can only be achieved at a significant cost. However, these certifications are possible with a well-planned and carefully thought-out approach,” she said.

“Waste management is a critical part of any large-scale construction or demolition project. It is vital that clients, engineers, and contractors communicate clearly prior to commencement of a project to ensure alignment across all spheres. This ensures a co-operative and collaborative approach to the works, with different people actively seeking practical, cost-effective and responsible solutions to very basic problems.”

Bester said this meant all role players must be involved from the outset of a project, which can be achieved by determining what the thresholds are, and then seeking alternative solutions that can meet these thresholds, while still being cost-sensitive.

The vast majority of construction materials are able to be sorted and cleaned mechanically either prior to or during demolition activities. Hazardous material abatement is crucial to remove the potential risk and contaminants from a structure prior to demolition, thereby resulting in ‘clean’ rubble from a structure.

She said Jet Demolition always approaches a site with safety as a priority. “We will typically abate hazardous materials prior to demolition where practical, and then move on to the mechanical separation of materials during demolition.”

Here steel is set aside and processed for delivery to a foundry for recycling. Where possible, ‘clean’ demolition rubble is used as on-site layer works or backfill to voids. Any excess material is loaded and hauled for reuse.

What about the impact on landfill sites, which are themselves under pressure?

“There is no denying that a large proportion of demolition and construction rubble does go to registered landfill sites,” Bester said, adding that this material is often used to rehabilitate the landfill sites themselves.

She said most registered landfill sites have strict controls over the quality and quantum of material they accept. There is usually a strict grading in terms of the size limitation of the material accepted, with most material crushed prior to delivery. This material itself can then be used to cap the site, or even as an engineered fill to serve as a permeable drainage layer.

When there is material that cannot be suitably downsized and cleaned prior to disposal, the surcharge on the disposal is generally very high. This is specifically done to discourage the disposal of material that could otherwise have been recycled.

The fact that ‘clean’ material goes to landfill should not necessarily result in it being classified as waste. “What may be needed is a reclassification of the different waste materials,” said Bester. The vast majority of this material is being reused and recycled, albeit through a landfill facility for capping, a farmer for erosion control, or by local council for backfilling sinkholes. “This material is valuable and should be seen as such.”

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