A study done in Denmark found that as much as 34% of pre-wetted deicer is immediately lost because of bounce and scatter. That's 5.5 million tons, a $250 million value, in the ditch or bouncing into storm drains. Another 20% to 30% is thrown off the road within two hours for another $140 million in wasted investment.
All that salt, of course, eventually makes its way into lakes and rivers.
To reduce waste, you must control how much gets spread and where it gets spread. Controlling the amount discharged is done by properly calibrating spreaders. The process is different for every piece of equipment and different materials, so your team can benefit from some professional guidance. But once they're trained, calibration becomes something that gets done regularly before every winter season.
Controlling where deicer goes is the second half of the solution.
Mark Cornwell, founder of Sensible Salting Solutions LLC in Holly, Mich., and former chair of the University of Michigan's Salt Use Quality Improvement Team, has developed a “material application grid” winter crews can use to find out how adjusting equipment, materials, and driver behavior affects dispersion.
The grid should be painted on level pavement wherever there's enough space to allow trucks to approach operational speeds. The design can be configured to mimic two- or three-lane roads and has a “penalty box” that shows how much material typically ends up on the shoulder and in gutters and ditches. After an application run, operators sweep, bag, and weigh material scattered within selected blocks of the grid.
Such analyses are one reason the Farmington Hills Department of Public Services in Michigan received the American Public Works Association's 2011 Excellence in Snow and Ice Control Award. Faced with the price of salt almost doubling over the past four years, higher-than-average snowfall, and a 25% reduction in operators, the department had to consider a new approach to winter maintenance.
Improved calibration was an obvious first step, so operators painted the grid in the equipment yard before the snow started flying and ran their spreaders through the calibration process.
Nothing beats a good visual
“It's a real eye-opener,” says Road Maintenance Supervisor Bryan Pickworth. Running the spreaders through the grid allowed operators to visually witness the benefits of spreading wet versus dry material. It also let them see first-hand the effect that spinner and travel speed have on material performance. “Being able to see the difference in application for various speeds and settings really clicked with the operators.”
To get the most durability out of the grid markings, Cornell suggests pressure-washing the area and applying a fresh seal coat (with a bucket and mop if need be) before applying quality pavement marking paint. Pickworth recommends locating the grid near salt storage and using a pickup truck or tractor with a sweeper to quickly and efficiently clean up salt that isn't being measured.
Any other words of advice?
“Slow down the spinner speed! Reduce the speed of the trucks!”
—Terance McNinch (firstname.lastname@example.org) is the retired director of the Michigan Local Technical Assistance Program (LTAP).