The formula
A diversion rate is the weight of material kept out of the landfill divided by the weight of everything hauled off the job.
We measure it in tons because that's what a scale reports. A count of containers tells you how many times a truck showed up, but it doesn't tell you what was in them.
Where the tons come from
Every load that leaves a site crosses a scale at the facility that receives it. The facility prints a ticket with the date, the ticket number, the hauler and the net weight. That ticket is the source for everything else.
On a real project the tickets arrive in several forms. Some are scanned paper, some are rows in a hauler's spreadsheet, and some sit in a general contractor's own tracking portal. We collect all of them and check each ticket weight against the invoice for the same haul.
One mixed load, split by material
Clean loads are simple. A container of scrap metal that goes to a metal recycler is recycled, and the whole weight counts.
Commingled loads take another step. The facility sorts the load and reports what it found. Here is one real load from one of our projects, as the facility reported it.
That split usually comes back about a month after the haul. Until it does, the load is pending, and a careful report says so.
Three places the number goes wrong
Counting containers instead of weight. An estimate built from "twelve 30-yard dumpsters" isn't a diversion rate, so ask for the scale tickets.
Calling a commingled load recycled on the day it was hauled. Nobody knows what was in it yet. If a report shows 100% on a mixed load in the same month it left the site, someone guessed.
Assuming the material decides the answer. Whether a load counts as recycled depends on where it went. The same drywall can be recycled at one facility and landfilled at another, so the facility on the ticket matters as much as the material.
What a report should show
A report you can hand to an owner has a header with the project, the client, the period and the vendor. It lists every haul with its date, ticket number, facility, material and weight. It totals tons hauled and tons recycled for the period and for the project to date, and somebody signs it.
On a hospital expansion in Lee's Summit, the report showed 31 tons hauled and 30 recycled, a 97% diversion rate, with the tonnage split between two projects that share a dumpster.
Read the case study