About half of the solid Waste generated worldwide are from building materials. There is an environmental impact of building Material at every step of the building process – extraction of raw materials, processing, manufacturing, transportation, construction and finally disposal.

According to this Construction and Demolition Waste Status Report, “…total of 19.0 million tonnes of construction and demolition (C&D) waste was generated in Australia in 2008-09. Of this total waste stream, 8.5 million tonnes was disposed to landfill while 10.5 million tonnes, or 55%, was recovered and recycled.”

It is essential for governments and authorities to consider that the built environment of the future is being constructed at the beginning of a new ecological era. Governments must now respond to the challenges of environmental sustainability, and industry must respond to the challenges of low-carbon economies and resource depletion.

If we are to move towards sustainable development, we can no longer rely on reclamation/landfills to accept most of the inert construction waste. Although there are many initiatives to reduce and reuse construction waste, a substantial amount of materials still require disposal, either at public fill reception facilities or at landfills. Landfills also pose a great threat to health and safety.

Planning

During the planning phase of the construction project, it is important to understand what excess materials are likely to be generated and then focus on how the generation of those excess materials can either be avoided or the material can be diverted from landfill.

It is now prudent and good practice to develop a Construction Waste Management plan. The key objectives of any construction waste management plan should be to:

• Minimise the amount of waste generated as part of the project
• Maximise the amount of material which is sent for reuse, recycling or reprocessing
• Minimise the amount of material sent to landfill

The document Construction Waste Management: Plan Guidelines highlights some key elements when developing and implementing a construction waste management plan:

1. Waste streams: identify which waste streams are likely to be generated and estimate the approximate amounts of material
2. Focus on waste avoidance: instead of managing the waste once it has been generated, look at ways to avoid the generation of that waste in the first place
3. Services: select an appropriately qualified waste management contractor who will provide services for the waste streams generated and data on waste/recycling generation
4. On-site: understand how the waste management system will work on-site, including bin placement and access
5. Clearly assign and communicate responsibilities: ensure that those involved in the construction are aware of their responsibilities in relation to the construction waste management plan
6. Engage and educate personnel: be clear about how the various elements of the waste management plan will be implemented and ensure personnel have an opportunity to provide feedback on what is/isn’t working
7. Monitor: to ensure the plan is being implement, monitor on-site
8. Evaluate: once the project is complete, evaluate your estimates in the plan against the actual data for waste generated and consider feedback from personnel.

Some Waste Management Processes

Jobsite Sorting

When working on the site it is important to efficiently identify and sort materials. This helps in managing the economic viability of diverting construction debris from disposal.

Materials can be sorted into a number of containers. It might be advisable to hire service companies that specialize in the management of specific types of waste at the jobsite. Consider using the least number of containers to keep container volumes high. This will reduce transportation trips and costs, and keep the jobsite clear of obstructions.

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Tipping

It is important for the construction management team to identify the loads on arrival at construction and demolition. Debris diversion facilities is an important step in ensuring materials are appropriately handled. The facility management plans will describe materials that can be accepted. If not acceptable they must be turned away and disposed of in a sanitary landfill. Be mindful in identifying four hazardous waste characteristics: corrosivity, ignitability, reactivity, and toxicity.

Picking

Construction materials are typically handled with special equipment that is designed to support heavy loads and resist abrasion. A hydraulic excavator or a grapple is used to pick through the stockpile of material.

Materials such as steel reinforcing bar, carpeting, large pieces of wood, concrete and materials with dimensions greater than 3 feet are usually picked before the sorting process can begin.

Sorting

Sorting is a labour intensive task, where works manually sort materials on a chain belt. Materials are identified, grabbed, and deposited in vertical openings at each sort station. The effectiveness of the manual sort line is largely determined by the performance of the picking operation which precedes it; for example, large materials on the belt can be difficult to manage and or obstruct recoverable materials passing by on the belt beneath.

Containerization and Transport

Picked and sorted materials are deposited by means of equipment and manual labor into industrial containers of various types. Combination compactor-balers are used in some applications to produce dense bales of materials.

On containerized, recyclable materials are commoditized and traded in the global marketplace.

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Diversion or Disposal

Diverted materials are destined for incorporation in new products as recycled material, or are processed for reuse. Materials destined for disposal in landfills include refuse, materials contaminated with waste or which have been ruined, and materials for which markets do not exist.

Challenges for Proper Waste Management

Knowledge Across Industry and Requirement for Training

Organisations like The Institute of Public Works Engineering Australia Limited are developing courses to help project managers and engineers to understand the specifications of new materials such as recycled aggregates and substitute materials, and to learn how to incorporate them into projects.

Unfortunately, these courses are limited in reach and adoption. With the fast changing world of building materials,  the courses are not updated as often as needed.

Cross-contamination of Wastes

When recovering useful materials from construction sites, cross-contamination of materials can hamper the recycling process. Asbestos contamination is a well-documented problem and a significant issue on renovation and demolition sites. When materials are captured closer to the source, there is opportunity for higher recovery rates.

Technological Barriers

There is a major lacuna in the market when it comes having the right technology or equipment to sufficiently clean or segregate materials. This is particularly evident with the timber waste stream where there is contamination from treated timber products. There is a clear need for investment in research and development to overcome technological barriers.

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