Diversion rates are routinely over-claimed

The number that is almost always wrong

If one figure in corporate environmental reporting deserves to be treated with suspicion by default, it is the diversion rate. Not because anybody is lying, but because of how it is usually produced: backwards, from what was purchased, rather than forwards, from what actually left the site.

Purchase data is excellent evidence of what came in. It says nothing reliable about where any of it went, and the gap between those two questions is where most of the over-claiming happens — quietly, and in good faith.

What a checkable rate needs

A weight, a destination and a ticket with a date on it. Everything else is inference, and inference is what turns a diversion rate into a figure nobody can defend the moment somebody asks where one particular load actually ended up.

• Gate weights for outbound loads, not inferred tonnages
• Streams kept apart, because a blended rate hides the failing one
• The receiving facility named, so somebody could telephone it
• Contamination rejected at the far end taken back out of the total

The rejected load problem

A tonne sent for recycling and landfilled at the receiving end was never diverted, however it was recorded on departure. Contamination rates at the far end are knowable — the facility will tell you — and almost nobody asks, because asking lowers the number.

Where a figure falls once it is properly evidenced, that fall is the most useful thing the engagement produced. It is also the hardest part to explain upward.

What to expect when you check

A lower rate than the one being quoted internally, by a margin roughly equal to the unticketed volume. The first eight months are the uncomfortable ones. After that the tickets exist and the figure stops moving.