Question 12 of 17: When Source Separation Is Warranted

Question 12: When Source Separation Is Warranted (5 marks)

Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.

Source separation is warranted when several conditions hold together, rather than as a universal default. It is warranted when the waste stream contains a significant fraction of high-value recyclables (clean paper, metals, certain plastics) whose market value depends on a purity level that only separation at the point of generation, not later mechanical sorting of a mixed stream, can reliably deliver — contamination in a mixed load can render an otherwise recoverable material unmarketable. It is warranted when hazardous or special wastes (batteries, electronic waste, household chemicals, sharps) must, for safety and regulatory reasons, be kept out of the general waste stream at the source rather than sorted out afterward. It is warranted when clean organic feedstock is needed for composting or anaerobic digestion, since contamination introduced by mixed collection degrades finished-compost quality and marketability. It is warranted when landfill capacity is scarce or tipping costs are high, making the added cost of multi-stream collection economically justified by the airspace and disposal cost avoided. Finally, it depends on whether the community has the public-education infrastructure and participation willingness to sustain it — source separation is not automatically the right choice in, for example, a very low-density rural area where the added haul cost of multiple collection streams can exceed the value of the material recovered.