Material, a byproduct of wood processing, unavailable locally
By Sandra Strieby
A key ingredient in the Methow Valley’s recipe for dust control is unavailable this year, leaving home owners’ associations, driveway owners, and road managers to work out whether or how they will treat dirt and gravel roads in the dry months ahead.
Lignin sulfonate, a by-product of wood processing, is a polymer that’s commonly sprayed on traveled surfaces to bind dust. Locally, it’s been applied by Cascade Concrete in years past. According to the concrete plant’s Loren Curtis, the mill that’s his usual source is temporarily closed. Importing lignin from out of state would more than double last year’s cost, from $315 to $650 per ton, said Curtis.
One alternative is a magnesium chloride spray, similar to those used locally to melt ice in the winter and stabilize county roads in the summer. Cascade Concrete will use a magnesium chloride spray formulated for dust suppression this year. It’s more expensive than the lignin used last year, but costs considerably less than lignin would in 2023.
Lignin-based sprays are considered more benign than magnesium chloride, which is hard on vehicles and roadside vegetation. Lignin sprays are not entirely without risk — if enough were to enter surface water, decomposing lignin could cause high biological oxygen demand (BOD) that would be harmful to aquatic life, much like an algal bloom.
Looking at options
Local homeowners’ associations are assessing options and looking for ways to make the best of the situation. The Sun Mountain Ranch Club’s current plan is to forego treatment this year, according to the property owners’ association’s road committee. The Edelweiss Maintenance Commission is considering applying lignin at a lower rate to reduce costs, and is also researching environmentally-friendly alternatives, according to board member Simon Windell.
The Wolf Creek Property Owners Association’s board of directors is “still working out what to do,” according to the board’s architectural chair, Jason Williams. The association is likely to treat fewer roads than usual and adjust the treatment schedule to compensate for the high cost of magnesium chloride, Williams said in an email.
Controlling dust has value beyond the obvious effects on quality of life. So-called “fugitive dust” causes a host of problems, affecting human and animal health, crop productivity, and visibility, increasing vehicle and equipment wear, and, of course, getting things dirty.
Like smoke, dust can have long-lasting effects on respiratory health. According to the Department of Ecology’s Outdoor Dust Management web page, “While larger dust particles may sting and irritate your eyes, smaller particles of dust are of greater concern to people’s health because they can lodge deep into your lungs.” Dust can include the same PM2.5 particles that make wildfire smoke so hazardous.
Dust can also transport lead and arsenic that may have accumulated in soil as a result of past agricultural spraying or lead paint. Ecology’s recommendations for protection from harmful chemicals in the soil can be helpful for dealing with any summer dust. They’re available online at https://ecology.wa.gov/Spills-Cleanup/Contamination-cleanup/Dirt-Alert-program/Healthy-actions.
Like heat, dust may be an unavoidable element of Methow Valley summers. Minimizing travel on unpaved roads, and driving more slowly when you do sally out, can significantly reduce dust, according to Ecology. It’s one trial over which the wayfarer can exercise some control.