Among 10 products, some with exotic names, it turns out that saltwater from oil wells might work best at keeping road dust at a minimum in the oil patch.
Ideally, though, the water would have a higher-than-usual concentration of magnesium chloride and wells that produce it could be an inexpensive go-to source for counties and companies trying to quell dust on oil-traffic gravel roads.
That’s the outcome of a $440,000 study funded by the Petroleum Research Fund and McKenzie and Dunn counties.
Francis Schwindt, formerly with the state Health Department, headed the effort to field test 10 products on select gravel roads to see which works best.
Counties have been spraying gravel roads with magnesium chloride, dissolved in water, for several years, but it’s expensive. The idea behind the study was to see if any other products hold up to the beating of oil and water tankers.
Among the products synthetic, molecular and petroleum concoctions with such names as Rhino Snot, Coherex and Wisp.
Schwindt said he had high hopes — especially that crude oil might set up similar to an asphalt covering — but none turned out as well.
“Magnesium chloride is the most effective with the volume and type of traffic. Oilfield brine shows some promise, but we need sources that have a higher percentage of magnesium chloride,” he said. “I had really high hopes with the crude, but it was not effective at all. It coated the surface OK, but when the trucks went over it, the dust fines boiled up behind the truck. It just didn’t glue the particles.”
His next step will be to work with the Department of Mineral Resources and others to find out if anyone is analyzing the saltwater produced with oil in order to identify a local resource for a high magnesium chloride ratio.
Otherwise, the product is shipped in at the rate of 90 cents a gallon, costing counties about $5,000 a mile to apply.
Schwindt said it holds the road surface together and holds down dust for up to a year after three applications spaced fairly close together.
It works because the magnesium chloride attracts water molecules and keeps the road surface slightly damp.
He said the study found the road itself should contain good quality aggregate with native clay. The clay improves road stability and dust control, especially in combination with magnesium chloride, he said.