The domestic Oil and Gas boom has had the number of active drilling pads soar to near record levels and, prior to the softening market, had the US projected to be the largest crude producer in the world in 2015 (courtesy: dailyreckoner.com). One of the effects of the boom has been a proliferation of wastewater, and an understandable urge to put this material to use. On the surface, O&G wastewater has appeared to be a viable agent for application on roads and pads for the purposes of dust control, as it contains a significant level of sodium chloride.
While attractive as a way to address road and pad needs with a readily available operating byproduct, it is important that this new trend be scientifically vetted. Unfortunately the wastewater coming out of wells does not hold up as a viable product option. Here’s why.
A basic, but often overlooked, aspect of effective dust control relates to what happens to water on a roadway. All effective dust control is based on keeping the road moist, as this is what binds the dust and prevents it from shooting into the air. Magnesium chloride and Calcium chloride are effective agents, and industry standards, because both molecules are hygroscopic, meaning they have a very high affinity for water. This also means that they both have a wide range of temperature and humidity levels at which they will remain liquid. Additionally, they both attract moisture from the atmosphere, furthering their effectiveness.
Sodium chloride, on the other hand, is not hygroscopic. It may be a chloride, but it does not share the affinity for moisture that its cousins do, and, therefore, will not contribute to the moisture of the road. Here’s a practical example of this scientific fact in action. After a snow storm when paved roads are salted with straight white salt, the salt melts into a brine and serves to melt the snow and ice. From there, however, the water from the brine evaporates once temperatures warm up again (because NaCl is not hygroscopic) leaving a film of white salt crystals on the ground (notice how strikingly apparent this after your next snow event). Those crystals then contribute to dust after the storm. This dynamic will play out on unpaved roads just as easily as it does on paved roads. The water from the wastewater will evaporate and the salt crystals will actually become part of the problem that users are trying to solve. The truth is, any material of this sort will need at least 23% of its volume to be MgCl2 or CaCl2 to be an effect dust control agent.
Everyone likes a quick and convenient solution to their problems. In this case, however, the quick and easy way will actually make things worse, not better. As always, thanks for reading and please reach out to learn more!
