Engineering & Mining Journal

JUL 2018

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WATER REUSE STRATEGIES 34 E&MJ • JULY 2018 www.e-mj.com public perception of the White Springs mining operation is they could have some impact on the springs in the region and, therefore, it must be "very cognizant of their social obligation to operate in an en- vironmentally responsible manner." Upper Suwanee River Springs Restoration In 2015, the mining company, the Su- wannee River Water Management District and the FDEP joined forces to launch the Eagle Lake/Upper Suwannee River Springs Enhancement project. Water is a key asset at the White Springs mine, explaining that the typi- cal mining approach is to strip off about 20 feet (ft) to 30 ft of non-ore bearing overburden with a dragline, essentially re- moving the top layer of sand and clay to get to the phosphorus bearing ore. Water is then used to mobilize the ore, which is pumped to the mine processing facili - ties. Sands and clays are separated from the phosphate-bearing minerals and then the water is sent to large settling areas for treatment, with a significant portion of the treated water being discharged to the mine's recirculation system. As dictated by the mines overall water balance, a por- tion of the treated water is discharged to the river via a NPDES discharge point. The objectives of this project were the beneficial use of a portion of the discharge water from the mine, reducing the overall mine discharge and associated nutrient load, and reducing the fresh groundwater use from the Floridan aquifer system. To achieve these objectives, the proj- ect took water from as close as possible to the point of discharge and pumped the water to a location within the mine where it would be available for reuse. This required the construction of a new pump station and a pair of pipelines to return the water back to the mine so that it can reuse the discharge in their oper- ation. Dinges added that the mine does not reuse all the discharge water owing to capacity constraints, but suggested that this could be an opportunity to develop more projects that could beneficially uti- lize additional discharge water. The $3.6 million project was com- pleted in August 2016, resulting in the reduction of nutrient loading into the Upper Suwannee River basin by up to 140,000 pounds per year (lb/y) of total nitrogen and up to 110,000 lb/y of total phosphorus. The project reduces the mine's groundwater requirements with a reduc- tion of withdrawal from the Floridan aqui- fer system of 20 million gallons per day. This provides benefits to the springs along the Upper Suwannee River, including Bell Springs, White Sulphur Springs and Blue Sink Spring. There are also benefits to re- gional water supplies from the reduction in groundwater pumping. "This project helps maintain the bal- ance between water needs of natural sys- tems and humans," Dinges said. Innovative Partnerships One of the reasons for the success of the project was the innovative private-public partnership. "They worked together to con- ceptualize, design and implement this proj- ect," Dinges said. "All three of these enti- ties were financial partners, which played a major role in the project's success. There were mutual benefits for all the parties, as well as significant public benefit." He added that the development of nu- meric nutrient criteria across the country will lead to constraints that will affect all dischargers within those watersheds, including mining operations, which will have to look for sustainable approaches for managing their water. "Any mine that discharges water will need to manage water and find innovative ways to mitigate their impact on water bod- ies of the area in which they operate. Reuse strategies are a great approach for active operations and partnerships really are an ef- fective way for these projects to be come to fruition. This project demonstrates the true effectiveness of public-private partnerships and emphasizes the benefits that can be created when public and private entities put their heads together for a mutual cause." Though the cost for complying with the numeric nutrient water criteria standards may be fairly significant, the direct and indirect costs of non-compliance are far more onerous, particularly when consider- ing a mine's social license to operate. En- suring the continued sustainability of water use hinges heavily on the industry's ability to make better use of this limited resource. "Sustainability strategies consider a 'One Water' philosophy that treats water as a reusable resource to be conserved. Water reuse strategies offer sustainable benefits for both public and private insti- tutions and ensure clean and abundant water to support the needs of future gen- erations and natural systems." This article was submitted by Black & Ve- atch, a leader in engineering, procurement and construction services, based in Over- land Park, Kansas. Jon Dinges, P.E., is the senior water resources planning leader for Black & Veatch's water business. Using an innovative water reuse program, a mine was able to reduce its load on the Florida aquifer and the surrounding springs.

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