That Sinkhole Feeling, Again
During a visit to the Intrepid Potash - Moab, Utah website we were pleased to see new safety related information regarding the mining and processing of potash (potassium chloride) and salt (sodium chloride) crystals at their Cane Creek potash plant. In an earlier article, we had criticized the company for not providing holding ponds designed to catch leaks or overflow from settling ponds at a higher elevation.
Their website now states that, “the solar ponds are lined with heavy vinyl to 
prevent valuable brine from leaking into the ground and the Colorado River. A series of holding ponds have been constructed to catch any spills and return potassium-rich brine to the ponds.” Whether these safety features existed all along, or are recent additions, we do not know. Either way, Intrepid's release of more information about their operation, rather than less is laudable.
prevent valuable brine from leaking into the ground and the Colorado River. A series of holding ponds have been constructed to catch any spills and return potassium-rich brine to the ponds.” Whether these safety features existed all along, or are recent additions, we do not know. Either way, Intrepid's release of more information about their operation, rather than less is laudable.In the event of a catastrophic failure at the upper ponds, what percentage of the brine might the holding ponds catch and retain? With the continued absence of information regarding holding pond capacity, we can only guess and hope that it is adequate. “Adequate for what?” you might ask. We can think of at least two scenarios in which a catastrophic failure might test Intrepid's holding pond design and capacity.
First is weather. What is the expected level of water flow into the settling ponds during a “one hundred year flood”? What about the "one thousand year flood"? In order to determine the size of a one hundred or one thousand year flood within the Shafer Basin and Potash, researchers must consider both historical data and paleoflood records.
Now that a drier climate in the Four Corners region is an established fact, we can expect storm and flood activities to increase in intensity, if not in number. Lack of an historical record does not preclude the formation of larger storms there in the future. In that regard, we would not be happy with a holding pond system that provides less than full containment of all settling pond brine.
A second threat at the Cane Creek Plant and its ponds results from the solution mining of potash itself. The Intrepid Potash - Moab Utah website indicates that, “water from the nearby Colorado River is pumped through injection wells into the underground mine. The water dissolves the potash from layers buried approximately 3,000 feet below the surface.” Missing from the company’s website is information on injection well locations, and their proximity to the fragile holding ponds.
In order to understand the importance of proximity, we need look no further than the City of Carlsbad, New Mexico. According to a recent Los Angeles 
Times article, New Mexico mines used a solution-mining technique similar to that of Intrepid, at Moab. Over the years, six million cubic feet of brine solution mining has been extracted from a salt deposit located directly beneath Carlsbad.
Times article, New Mexico mines used a solution-mining technique similar to that of Intrepid, at Moab. Over the years, six million cubic feet of brine solution mining has been extracted from a salt deposit located directly beneath Carlsbad.Although there has not yet been a collapse at the Carlsbad mine, in 2008 two similar mines north of the city experienced catastrophic failures. With the collapse of the overlying rock, each of those mines became a sinkhole four hundred feet across and one hundred feet deep. Since the mines operated within state and federal guidelines, there does not appear to be easy recourse against them. The state and the mine operators can simply call these unexpected events “Acts of God” and then proceed to disown any further liability.
In the case of Carlsbad, New Mexico, a collapse under the busiest intersection in town is a real possibility. Rail lines, an irrigation ditch and a mobile home park are now under threat of collapse. In the case of Intrepid Potash – Moab, Utah, no one knows how likely a catastrophic mine collapse might be. In an event similar to the Carlsbad scenario, might the solar ponds disappear into a sinkhole? Worse yet, could gravity cause the brine to cascade downhill towards the holding ponds and the Colorado River below?
Email James McGillis
