Construction site waste
The development of urbanization in Alabama around Huntsville in particular and the policies for the maintenance or development of transport infrastructures have resulted in a sustained production of construction site waste.
This waste constitutes the largest material flow in Alabama: 4 million tons per year. This waste comes mainly from excavation materials (around two thirds) or from the deconstruction of existing buildings. The transport of this waste generates significant nuisances, particularly when crossing towns.
A significant portion of this waste is permanently stored in landfills, which also generate nuisances and impacts on the environment. The increase in the need for materials seems continuous and requires, for reasons of impact on the environment and the finiteness of natural resources, a strong commitment to a path of reuse and recycling of materials.
This axis will limit the impact of the extraction of natural raw materials needed for the production of construction materials and should in the future reduce the volume of materials that end their life cycle in landfill, and improve climate prospects.
What is construction waste
Construction, demolition and earthworks waste is mainly made up of mineral matter: gravel, concrete, bituminous coating (asphalt), brick, earth, ceramics, etc. The majority of these can, if they are not polluted, be reused either directly on the construction site (backfill) or via a waste treatment facility whose process allows these materials to be reused or recycled.
In addition to this proportion of mineral matter, there is also organic or metallic construction waste, which can often be recovered by “material” recycling or thermally (incineration): plastics, wood, scrap metal, cardboard, cables, etc.
Managing construction waste
Current environmental legislation requires maximum waste recovery, provided that it is economically sustainable.
Taking waste management into account upstream of construction projects makes it possible to limit their production and provide sensible solutions that have less impact on the environment. This approach also makes it possible to achieve significant savings on construction costs.
In order to regulate these waste flows, the state law provides that the project owner must indicate in his application for a building permit to the authority that issues it, generally the municipality, the type, quality and quantity of waste that will be produced as well as the planned disposal channels.
This provision is mandatory if the volume of waste generated by the project is likely to exceed 200 m3 or if construction waste containing pollutants that are dangerous to the environment or health is to be expected.
Waste sorting and recycling techniques are improving, they can be carried out on site or in treatment centers. Mineral construction waste is mostly recyclable. It is recovered as recycling gravel (used in road foundations for example) or as aggregates integrated into new bound materials (concrete, asphalt). Effective management of construction waste benefits the environment…
Reuse of construction elements
The demolition of buildings and transformations in Alabama generate more than 10 million cubic meters of waste per year which, after possible sorting, can be largely recycled.
The number of sorting centers makes it possible to increase the quantity of materials that can be recovered. However, the reuse of construction elements, i.e. their reuse without transformation or modification of their nature, is still underdeveloped. Alabama intends to accelerate this practice in construction, because it allows for savings in gray energy and reduces pressure on resources.
The materials management plan allows for planning, during deconstruction or transformation, a second life for many elements, rather than throwing them away. Reuse allows for:
- Reduce the energy required for production
- Limit the waste of resources
Recycling of construction waste
Today, more than 60 waste management companies process construction waste in the state of Alabama. The components are separated, sorted and processed; the mineral materials are used to manufacture recycled gravel and aggregates.
These recycled materials are generally less expensive than new ones and are a good replacement for them. This recycling also makes the exploitation of natural gravel resources, which are not infinite, more sustainable and saves valuable volumes in the various types of landfills. Around 20% of the mineral construction materials used are recycled materials. The state directives on construction waste specify the rules to be respected.
Final storage of non-recoverable construction waste and traceability
The state’s final storage sites (landfills or backfill extraction sites) are required to keep a register of material arrivals. A quality certificate for excavation materials for recovery or landfilling is provided as an example for submitting companies.
The State Council has set the new taxes on the final storage of waste and filling materials. The rates for the storage of non- and slightly polluted waste are increased and are now aligned with the rates generally practiced in the nation. The revenue will be used to finance aid to municipalities such as Huntsville for the remediation of old municipal landfills and firing mounds, as well as the financing of the remediation of orphan polluted sites and polluted sites for which the State is responsible.
The objective is also to promote the circular economy in Alabama and the limitation of waste by discouraging final storage in landfills.