Water is an increasingly scarce and valued resource across the globe. Governments, communities and industries are experiencing unprecedented concern as a result of increasing demand from fast growing populations, unsustainable water practices and persistent droughts. Climate change is expected to place more pressure on available water resources, with some regions predicted to become much drier and other regions wetter.
Kennecott stormwater basins
Over the past three years, Kennecott has improved existing and added new stormwater basins to increase capacity and mitigate runoff when large rain events occur. The new system was designed and constructed well beyond
We use water in every stage of our operation and business: for exploration, mining, concentrating, smelting, refining and power generation. We need water to process and mine ore, produce metal and power, cool equipment, transport tailings, suppress dust, and for washing and drinking. Our water system is complex, with miles of pipes and associated infrastructure that move water up to 17 miles from one facility to another.
Our primary water sources include groundwater from wells and springs near our operations and surface water. More than 70 percent of the total water we withdraw comes from groundwater sources with the remainder coming from surface water sources. The majority of the water we withdraw is recycled and reused over and over again. On average, we recycle about 60 percent of the water we withdraw to minimize importing additional water resources.
In the arid west where Utah is the nation’s second driest state, water is an important natural resource. At Kennecott, we manage our water resources to ensure efficient, safe and sustainable use and to protect water resources in and around our operations. Our approach to align day-to-day production with long-term planning includes:
- Minimizing the amount of new, clean water required for copper production operations by recycling
- Continuously seeking opportunities to more efficiently use our water
- Separating waters of different quality to optimize the best use
We treat water using reverse osmosis, one of the most advanced technologies used to treat water today, at several of our facilities (such as at the smelter, copper refinery and power plant) to be used in different processes. We also treat water at certain sites for washing and culinary use for employees at our operations.
Most notably, in 2006, we completed a large reverse osmosis water treatment plant located on the south end of our operation to treat groundwater that was historically affected by mining activities. We extract impacted groundwater by pumping a network of wells and then conveying it for treatment at this facility. The facility treats approximately 3,000 gallons of water per minute and provides enough potable water for 4,300 homes each year. Water from this treatment facility is delivered to the Jordan Valley Water Conservancy District for distribution to its customers.
Beginning in the 1920s, early miners at Bingham Canyon began applying water to waste rock piles to dissolve, or leach, the low grades of copper in the waste rock. They collected and processed the leach water from the toe of the piles to recover the copper. The leach system was upgraded and expanded over the years. However, in 2000, we stopped the application of water on the waste rock. Rain and snowmelt continue to infiltrate the waste rock, and we continue to capture this water at our collection structures.
We collect and treat water that contacts the waste rock to prevent pollution. A series of 29 acid-resistant concrete walls have been constructed in the drainages below the waste rock emplacements on the east and south side of the pit. These walls extend below the surface to bedrock and capture surface water and shallow groundwater. We continue to recover copper from this water and then mix the acidic water with mill tailings to neutralize the water.
We have allocated tremendous resources in the construction of cut-off walls and complex water collection and conveyance systems consisting of double-lined pipes and holding ponds. We have established primary and secondary containments for all potential contaminant storage containers and areas, coupled with an extensive and state-of-the-art monitoring program. We also capture all the meteoric water (water that comes from natural precipitation, such as rain or snow) that falls on our waste rock repositories.
Selenium is a naturally occurring trace mineral that can concentrate in the water. In small amounts, it is good for bird health but can be toxic in large doses.
The Great Salt Lake is a critical ecological resource and home to hundreds of thousands of birds each year. More than 250 species pass through, as the lake is an important migratory stop between North and South America.
Birds who feed at the lake ingest selenium through their diet, including brine shrimp and brine flies. Extensive selenium exposure can cause reproductive deformities and present problems with the hatching of bird eggs. Given the narrow range between background selenium and potential toxicity, the lower end of the proposed selenium thresholds for bird diets and eggs may fall at or only slightly above “normal” background selenium levels.
We have a permit through the Utah Department of Environmental Quality, Division of Water Quality, to discharge water with selenium into the Lake. This water is groundwater from the southern part of the Salt Lake Valley that undergoes our cleaning process. The permit allows for a concentration of 54 parts per billion in the water discharged to Great Salt Lake; we have never exceeded this amount permitted.