CIF in cooperation with the City of Barrie and its contractor, Waste Connections, recently funded a quantitative study to determine whether additional sorting effort at the curbside could significantly reduce the amount of ‘unsolicited’ material delivered to a MRF.
Curbside contamination consists of unsolicited materials (e. g., a running shoe in the Blue Box) and solicited materials that are too contaminated to process (e. g., newspaper soaked in motor oil). Contamination in single-stream and two-stream collection systems creates processing challenges at the MRF and increases disposal costs, resulting in higher program costs. By contrast, minimizing contamination in loads delivered to a MRF helps reduce processing costs and improves the marketability and revenue for sorted recyclables.
Steps in Barrie’s Curbside Contamination Reduction Study
The study undertaken in the City of Barrie included the following steps.
- Material was collected in a routine manner on a typical two-stream blue box route with the regular driver (Normal Sort).
- Material collected was sorted and weighed to determine contamination present in fibre and container streams during normal operations. On average the collection vehicle was stopped for 19 seconds at each home.
- At a later date on the same route and with the same driver, the driver applied additional effort to leave contamination at the curb. On average, stop time increased from 19 seconds to 52 seconds (Additional Sort).
- Material collected was again sorted and weighed to determine contamination present following the additional sorting effort at the curb. Driver performance was monitored to ensure diligent sorting efforts.
Results of the Study
Study findings are summarized below:
| Findings | Normal Sort | Additional Sort |
|---|---|---|
| Stop time (wheels stopped) | 19 seconds | 52 seconds |
| Total contamination set-out1 | 13.7 % (by resident) | 10.8% (by resident) |
| Contamination after sort at curbside (not at MRF) | 9.3 % (as received at MRF) | 5.2 % (as received at MRF) |
| Contamination removed by driver (%) | 4.40% | 5.60% |
1If the driver had collected everything
While it is acknowledged that material composition can vary significantly from week to week even on the same route, it is clear that significantly increasing the time available to remove contamination has only a minor overall impact on reducing the level of contamination present at the curb. Removal of contamination from the fibre stream was far more effective than from the container stream. This finding is reasonable given the lightweight and complex packaging used for food and beverages.
Study findings demonstrate that a gain of only 1.2% (5. 6% – 4. 4%) was achieved by more than doubling the time spent sorting at each stop. The additional time spent sorting would significantly increase curbside collection costs.
It is concluded that additional curbside sorting is not a cost-effective strategy to reduce contamination and residue levels at MRFs.
Study to Assist All Parties
As responsible operators, municipalities and stewardship organizations strive to keep contamination and residue levels as low as possible. The City of Barrie study was undertaken to assist all parties in determining effective methods to keep unsolicited material out of the Blue Box.
Contamination has become a contentious issue in discussions about a possible amended Blue Box Program Plan (aBBPP). As part of British Columbia’s (BC) transition to extended producer responsibility, participating municipalities providing collection services were required by contract to achieve contamination levels of 3% on inbound loads of collected recyclables. This target was proposed as part of Stewardship Ontario’s draft aBBPP but broadly viewed as operationally unachievable for a reasonable cost by professional program operators in Ontario. For reference purposes, Ontario residue levels generally range from approximately 7% for two-stream systems to 10-20% for one-stream systems.
This study sought to determine what the financial implications would be of achieving the proposed level. Collection costs reported in 2017 for Ontario totalled over $184 million. If stop times were doubled to allow for additional sortation at the curb, the program impact would be significant.
Across North America stringent end markets and the constant evolution of plastic and multi-material packaging will continue to cause contamination and residue levels to increase, in the absence of corrective action. Given the potential cost implications of trying to achieve extremely low curbside contamination targets, municipalities and producers may wish to invest in alternative strategies.
Corrective action for this complex problem could include improved public education. Based however, on past experience in Ontario, significant investment in public education yields only modest reductions in residue. This is due in part to public confusion over what is recyclable. Development of a simplified and standardized mix of acceptable materials would permit standardized promotion and education across the province which could prove to be a more cost effective approach.
In Conclusion…
The study findings suggest a standardized program coupled with an appropriate level of curbside due diligence and investment in more robust sortation systems in MRFs may ultimately prove to be the most cost effective strategy rather than trying to achieve artificially low curbside contamination levels. As municipalities and contractors work to adjust to new market expectations, perhaps this is the time to start thinking about what our expectations are of drivers at the curb within the challenging time constraints they currently endeavour to operate under.
The CIF would like to thank the City of Barrie and Waste Connections staff for their assistance with this project. For more information email CIF Staff.