Landfill owners and operators spend a lot of time focusing on containment: containment of waste; containment of leachate; containment of gas, litter, and odors. Quite often, containment of dust ranks near the bottom of the list. But that doesn’t lessen the importance of dust control. Originally published in MSW Management.
By Neal Bolton
If not properly controlled, fugitive dust can become a nuisance and health threat to your landfill’s workers, customers, and neighbors. It can damage your machines and create safety hazards by limiting visibility. Finally, if you don’t control dust, you could receive a citation for violating air quality rules, because dust control is a mandatory part of running a landfill.
At most landfills, dust originates from the excavation, hauling, and placement of cover soil, and from unpaved access roads. Loads of waste may also generate dust. Here are some ideas for controlling dust at your landfill.
Dust is considered to be a pollutant, and in some cases may actually contain hazardous materials, such as PCB’s or DDT. Some soils may even contain natural hazards, such as asbestos.
But, dust doesn’t have to be hazardous to be a hazard. Even what we might consider good, clean dust, right out of a virgin excavation area can hurt you.
Despite all the attention we’ve given to things like asbestos (which, by the way, is a mineral), breathing lots of dust—of any kind—can cause short-term or long-term lung damage. It can also cause eye irritation.
Yes, dust is a problem. No, it cannot be completely eliminated. But in most cases, it can be controlled. Here are some ideas.
Know Your Wind
Most landfills can identify where the prevailing wind comes from. Using that knowledge, try to keep dusty operations like grinding or excavating downwind of the tipping area and in a location where the dust won’t affect neighbors.
Use a Water Truck
The most common means of dust control is to use a water truck to spray the road. Along those lines, it’s usually most effective to use several light applications of water, rather than fewer heavy applications. This controls dust without making the road slippery or causing erosion.
Apply a Dust Palliative
Even though water is probably the most common solution, it is by no means the only one. Alternative dust-control measures include the use of dust palliatives, posting of speed limits, and surfacing the roadways.
Dust palliatives are materials that have the ability to reduce dust. One type of dust palliative controls dust by absorbing and retaining moisture. These types of dust palliatives include magnesium chloride, calcium chloride, or other similar hydrating chemicals. Lignin sulfonate, a byproduct of the wood-pulping process, also works by holding moisture. These materials are applied onto the road by spraying (in solution with water) or by applying in dry form either to the road surface or mixed into the soil or aggregate.
One drawback of these types of dust palliatives is that most of them are water-soluble and can be dissolved and washed away by rain or excessive watering with a water truck.
There are also petroleum-based dust palliatives. These materials are sprayed onto the surface of the road and form a hardened, semi-waterproof skin on the road. Petroleum-based materials will wear well as long as the sub-grade of the road is firm. However, any pumping in the road base will cause cracking and premature failure.
As vehicle speed increases, so does the dust.
Posting and enforcing reasonable onsite speed limits can also help to reduce dust and ensure a maximum useful life for access roads. This is oftentimes easier said than done. It is usually most effective to give authority to the site supervisor to issue citations, fines, or assess some other disciplinary action for violators. Even if we ignore the dust, speeding is a major safety problem.
Paved roads will create less dust and, surprisingly, may also cost less than gravel roads when maintenance costs are considered. Compared to a gravel road, a paved road will often pay for itself in three to five years.
Select “Low-Dust” Road Base
When constructing gravel roads, a certain amount of silt or clay material is desirable, as it serves as a binder and helps to retain moisture. However, it is usually this fine material that causes most dust problems. Slightly decreasing the amount of fines in the gravel may help to reduce the dust problem, but may very well cause some loss of strength in the road base. Before you change the aggregate mix, check with an engineer. Or, if you’re independent-minded, construct a short test section and see how well it works.
Regardless of your choice, before you implement any form of dust control, it’s a good idea to talk to your landfill’s regulators to determine that what you propose is safe and acceptable.