Why the invoice beat the quote

The call is always the same. The quote said one number, the invoice says another, and the difference is not small — it is usually a factor of ten or better. Nobody is trying to catch you out. What happened is that the load stopped being what it was booked as.

The load is graded once, at the gate, as a whole

A can does not get sorted into the bit you booked and the bit you did not. It goes over the weighbridge, it gets tipped on the picking floor, and somebody with thirty years of looking at rubble decides in about four seconds whether it is what the docket says.

If it is, it goes to the outlet for that stream and you are charged that stream’s rate on every tonne of it. If it is not, the whole load is re-graded to mixed and you are charged the mixed rate on every tonne of it. Not on the offending part. On the load.

That is not us being awkward. It is what the outlet does to us. A crusher that takes clean inert will reject a whole delivery for plasterboard, and a composting windrow will be condemned by a bag of plastic pots. We cannot sell half a rejected load.

The threshold is by weight, and weight is not what you notice

Every clean stream on the rate card publishes a contamination limit. It is a percentage of the load by weight, which catches people out in both directions.

A mattress looks enormous in a can and weighs almost nothing. Half a barrow of wet subsoil looks like nothing and weighs a hundred and forty kilos. On an eight tonne concrete can, that half barrow is most of the way to the ten per cent limit on its own, and the mattress is not — although the mattress will fail the load for a different reason, because it is upholstered and that makes it a persistent organic pollutant.

The practical version: watch the heavy wrong things, not the big wrong things.

It is almost always the last hour of the job

The pattern is so consistent we could set a clock by it. The can is loaded properly all week. Then on the Friday the site is being cleared, the skip is the only hole left, and everything that has been leaning against a wall since Monday goes in it.

At that point the argument for keeping the load clean has already been lost, so everything else goes in too — which is rational, and is exactly why the last demonstration on our home page keeps loading after the rate has flipped.

What to do instead

• Book two cans if the job has two streams. A 12 yard of clean inert beside a 20 yard of mixed is nearly always cheaper than one 30 of mixed, and it is one extra drop.
• Tell us before we collect, not after. If you know the load has gone, say so and we will book it as mixed. You pay the mixed rate either way; you do not also lose a day arguing about it.
• Keep the plasterboard out of everything. It is the single most common thing that re-grades an inert load, and it has its own outlet.
• If you do not know, describe the job. Ring the weighbridge and say what the work is. We book the stream for you and we are the ones who are wrong if it is wrong.