Tire-derived aggregate

TDA can be an excellent alternative to traditional forms of drainage material in leachate collection systems.

To acquire TDA for your next landfill cell please e-mail us at info@albertarecycling.ca or call our Tire Program Administrator at 1.888.999.8762.

What is TDA?

TDA (Tire-Derived Aggregate) is an engineered product made by mechanically shredding scrap tires. It is produced by Processors registered and approved by ARMA. Since the program began, municipalities across Alberta have benefitted from the use of approximately 600,000 tonnes of TDA as a drainage material in leachate collection systems. Used in nearly 200 landfill cells since 2006, this material is finding additional life for over two million Alberta scrap tires per year while reducing municipalities’ costs.

  • TDA can offer significant cost savings compared to conventional aggregate. Alberta’s Tire Recycling Program funds 100% of the cost to produce the material and a portion of the cost to deliver the finished material to the landfill site.
  • ARMA can work directly with municipalities, First Nations and Métis Settlements as well as waste authorities and commissions to order TDA for future landfill cells (up to three years in advance of the actual building of the cell).
  • Download the TDA Cost Tool Spreadsheet which enables applicants to apply their own expected unit rates for each of the input fields e.g. thickness of the waste pile, and cost of aggregate to calculate potential cost savings.

Not ALL TDA IS CREATED EQUAL

Just specifying ‘good’ material is not enough. Quality control and quality assurance processes are still necessary to enforce specifications during production. TDA that does not meet an engineer’s specification can be rejected. ARMA will provide technical guidance if requested.

Acceptable material for TDA
Acceptable for TDA
Unacceptable material for TDA
Not acceptable for TDA

HOW THE PROCESS WORKS

All parties involved in the landfill construction process have important roles to play to ensure the best possible result.

  • The landfill design engineer, working with the landfill manager, determines the best specification for the TDA to be used in the drainage blanket collection system. The amount of TDA to be ordered (and the cost savings over gravel) is determined using the TDA Calculator. The design engineer establishes a construction quality assurance program to ensure that TDA delivered to the site meets their design specifications.
  • The tire recycler selected for the project produces the TDA to meet the engineer’s specifications through proper operational and maintenance practices. “Out-of-spec” TDA (if any) is rejected by the design engineer or the landfill manager, no differently than any other sub-standard material that should not be incorporated into a project.
  • ARMA pays the recycler based on the tonnage of acceptable TDA delivered in accordance with the project specification (with a small contribution from the landfill owner). 

TDA that does not meet specifications is not eligible for funding by ARMA

WHAT HAPPENS WHEN TDA IS COMPRESSED IN THE LANDFILL?

Unlike gravel, TDA leachate collection blankets compress when buried beneath waste in a landfill. Solid material gets deposited in the spaces between the TDA particles (a process known as ‘clogging’), and the more the TDA blanket is compressed the smaller these spaces become and the more the clogging can affect leachate drainage performance. The testing work commissioned by Alberta Recycling investigated the compression behaviour of TDA under a variety of simulated landfill conditions using a purpose-built 1-D consolidometer. Testing results showed that even with the reduced particle spacing, the TDA spacing was still sufficient for use in a leachate collection layer.

TDA Compression in Landfill

PERMABILITY

Leachate builds up above a landfill liner unless it is drained to a collection point and removed. One key factor controlling the amount of leachate build-up is the permeability of the leachate blanket, and this is important in Alberta landfills because the amount of build-up is controlled by legislation. The testing work commissioned by ARMA investigated the permeability of TDA using a purpose-built 2-D permeameter which was designed specifically to accommodate TDA’s unique characteristics.

The test equipment applied vertical loads up to 300 kPa, simulating landfill heights of 30 to 40 m. The testing results confirmed that the permeability of TDA compressed under a vertical load of 375 kPa remained above the target value of 10-2 m/s.

TDA (Tire-Derived Aggregate) is an engineered product made by mechanically shredding scrap tires. It is produced by Processors registered and approved by ARMA. Since the program began, municipalities across Alberta have benefitted from the use of approximately 600,000 tonnes of TDA as a drainage material in leachate collection systems. Used in nearly 200 landfill cells since 2006, this material is finding additional life for over two million Alberta scrap tires per year while reducing municipalities’ costs.

  • TDA can offer significant cost savings compared to conventional aggregate. Alberta’s Tire Recycling Program funds 100% of the cost to produce the material and a portion of the cost to deliver the finished material to the landfill site.
  • ARMA can work directly with municipalities, First Nations and Métis Settlements as well as waste authorities and commissions to order TDA for future landfill cells (up to three years in advance of the actual building of the cell).
  • Download the TDA Cost Tool Spreadsheet which enables applicants to apply their own expected unit rates for each of the input fields e.g. thickness of the waste pile, and cost of aggregate to calculate potential cost savings.

To acquire TDA for your next landfill cell please e-mail us at info@albertarecycling.ca or call our Tire Program Administrator at 1.888.999.8762.

For further information on TDA download our Final Report on TDA Hydraulic Performance and Geomembrane Damage Potential or read the summary of the final report contained in our TDA Technical Bulletin.

Purpose-built 2-D permeameter
Purpose-built 2-D permeameter

PROTECTION FOR GEOMEMBRANES

Plastic liners (geomembranes) are increasingly being used in landfill lining systems. While they are exceptionally effective at containing liquids, they are relatively thin and need to be protected from sharp objects that can puncture them and compromise performance.

The testing commissioned by ARMA investigated the protection of geomembranes from the protruding wire of TDA particles and the edges of individual gravel particles. Different combinations of geomembranes, protective fabrics (geotextiles) and various types of TDA and gravel were used in testing. TDA particles were tested in winter conditions in a large testing frame outside a laboratory in Saskatoon. The frozen TDA particles were tested in place so the orientation of TDA particles relative to the geomembrane could be assessed.

Results confirmed that geomembrane liners should be separated from both TDA and gravel particles to avoid potentially high rates of puncture. Protruding wires from TDA particles were confirmed to have the potential to cause immediate geomembrane puncture, while gravel particles were confirmed to have the potential to cause excessive local strain in the underlying geomembrane.

Purpose-built large diameter TDA compression chamber
Purpose-built large diameter TDA compression chamber

For further information on TDA download our Final Report on TDA Hydraulic Performance and Geomembrane Damage Potential or read the summary of the final report contained in our TDA Technical Bulletin.

ARE YOU INTERESTED IN USING TIRE-DERIVED AGGREGATE (TDA) IN YOUR LANDFILL cell?

Call us at 1.888.999.8762 and speak with our Tire Program Administrator or email info@albertarecycling.ca