![]() ![]() The mined-out pits are used as water holding ponds to provide make-up water for the landlocked dredging operation. ![]() Two 30-inch (0.76 m) cutter-suction dredges remove approximately 40 feet (13.1 m) of the unstable material and transport it, via pipeline, as far as 15.000 feet (4921 m) to previously mined areas. The dredge/dragline method of mining, developed by Texasgulf personnel and unique to the industry, uses the dredging operation to provide the material needed to fill voids created by the draglines. After several alternate methods were evaluated, hydraulic dredging was chosen for removal of the saturated overburden. Of the 95 feet (31.2 m) of overburden, the top 36 feet (11.8 m), composed of highly saturated beds of silty clay, peat, sand and shell, were a major factor in 10 years of low ore recovery and very high mining costs. The Lee Creek operation is situated in low-lying terrain where the average elevation of +13 feet (4.26 m) above mean sea level provides an adverse environment for conventional dragline mining operations. This method, in addition to providing landfill for reclamation purposes, properly disposes of the nearly 18 million cubic yards of waste generated each year by the dredging operation. Long-term material disposal plans for waste products at Texasguif’s Lee Creek phosphate mining/chemical fertilizer complex in eastern North Carolina utilize dredged material as an integral component in dike construction. Dredging is defined as the excavation of natural material to provide and/or increase the dimensions of a waterway, or ensure that existing channels, berths or harbour works areas are maintained at their design specifications. ![]()
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