Recently, a major mining company spilled around 40,000 cubic meters of copper sulfate acid solution into the Bacanuchi and Sonora rivers, in the Mexican state of Sonora.
This spill led authorities to shut down wells in the affected areas, leading to water shortages for an estimated 22,000 inhabitants and prompting the distribution of water in trucks and plastic bottles. As schools across the country returned this week from the summer vacations, Sonora authorities kept 89 schools in nine municipalities closed until inspections can be completed and the quality of water guaranteed.
Also the Mexican environmental authority, Profepa, pressed charges against mining company for alleged violations of environmental laws, including possible negligence in the handling of dangerous substances. Profepa said the company could face fines up to 43 million pesos ($3.3 million), including 3 million pesos for violating waste-management regulations, in addition to any environmental cleanup costs and damages.
The mining company initially said that unseasonal rains in the region caused the acid solution to spill from a dam that is under construction for a new leaching plant at the mining complex. And they denied that it delayed alerting authorities to the spill when it occurred, and said it would cover all the damage from the incident.
On September 1st, the company issued an official report that says that one relevant factor of the accident was a construction defect in the seal of the pipe, which is part of the construction site of a new copper processing plant, and rainfall was a factor for the increased level of the solution in the containment tank.
The reputational fallout includes accusations of hiding information, calls for severe sanctions and the cancellation of their operating license in addition to the required reparations of the environmental damage. This is on top of an already damaged reputation among members of the mining industry in Mexico due several incidents in the past. This incident creates more tension with an already damaged relationship with certain communities, potentially affecting new projects or expansion of existing mines.
There is no doubt that the financial and reputational costs for this spill is huge. The question is whether or not this could have been prevented. It is hard to say without all the evidence, but it sounds like if the cause was a faulty pipe and an increase level in tailing pond, it could have been prevented with some critical measurement in place. If not prevented, at least improved with early notification to mitigate the damage caused by the spill.
Wireless instrumentation for process monitoring could be used for pressure or flow measurement in the pipe in order to detect low flow that is an indication of a spill or a plug. By having level measurement in certain areas of the tailing ponds using wireless level transmitters, the rapid rise of water to dangerous levels could be detected early.
With the use of wireless cameras, a rapid visual inspection of the area could be performed including the structure in the dam of the tailings pond. I think this incident will lead a more prevalent use of technologies for environmental purposes in mining, not only the use of wireless instrumentation but also wireless cameras and perhaps even drones to do visual inspection in hard to reach places.
This spill reminds us how costly an environmental incident can be, not only in environmental and financial impact, but also in reputation and credibility. Prevention is way better than the cure.