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. 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.
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. 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. After several alternate methods were evaluated, hydraulic dredging was chosen for removal of the saturated overburden.
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. 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 mined-out pits are used as water holding ponds to provide make-up water for the landlocked dredging operation.
Figures & Tables
Southeastern United States–Guidebook is comprised of twelve field trips that were organized for the Third Annual Midyear Meeting held in Raleigh, North Carolina in 1986. The spectrum of geologic time represented in the Upper Precambrian, Lower Paleozoic, Mesozoic, Cenozoic and the very Recent. The geologic provinces are the Valley and Ridge, Blue Ridge Mountains, Piedmont, and the Coastal Plain. Besides North Carolina, trips include Virginia, South Carolina and West Virginia.