A federal report on the accidental release of three million gallons of toxic water from an abandoned Colorado mine provides an in-depth, technical look at the incident. It also provides irrefutable evidence that proper engineering expertise is needed to protect the public health, safety, and welfare. Two of the three members of the evaluation and peer review teams were Professional Engineers.
The August 5 blowout at the Gold King Mine during a remediation project led by the Environmental Protection Agency highlighted flaws that are common in similar projects.
The technical evaluation was conducted by the Bureau of Reclamation and peer reviewed by the US Geological Survey and the Army Corps of Engineers. According to the report, better engineering could have prevented the blowout. “Abandoned mine guidelines and manuals provide detailed guidance on environmental sampling, waste characterization, and water treatment, with little appreciation for the engineering complexity of some abandoned mine projects that often require, but do not receive, a significant level of expertise,” the report says.
The report lists six factors that contributed to the blowout. They were the absence of: 1) an understanding that water impounded behind a blocked mine opening can create hydraulic forces similar to a dam; 2) analysis of potential failure modes; 3) analysis of downstream consequences if failure were to occur; 4) engineering considerations that analyzed the geologic and hydrologic conditions of the general area; 5) monitoring to ensure that the structure constructed to close the mine portal continued to perform as intended; and 6) an understanding of the groundwater system affecting all the mines in the area and the potential for work on one mine affecting conditions at another.
The report also recommends the following “prudent engineering considerations” that the EPA and others should follow: 1) incorporate a potential failure modes analysis into project planning; 2) conduct a downstream- consequences analysis and consider the effects of an accidental release as well as prevention measures; 3) directly measure the water conditions in a blocked mine prior to opening it; and 4) obtain independent expertise to review project plans and designs prior to implementation when significant consequences of failure are possible.