Tata, Solvay and Tronox all extract trona from Bed 17, the largest mineable seam of more than two dozen within the Patch, called the Known Sodium Leasing Area (KSLA). The KSLA is divided into a checkerboard pattern of mile-square land tracts, primarily owned by the federal government (48%), and Anadarko Minerals (48%), and the remainder by the state and private interests.

Across the KSLA, six beds, or seams, are the main focus of mining. Tata, Solvay and Tronox are working in Bed 17 while Ciner is active in the shallower Beds 25 and 24. Bed 14 contains an estimated 5.4 billion tons of recoverable reserves, while Bed 17 contains 7 billion tons and currently accounts for 75% of trona production. Depth-wise, these two beds are located within 100 vertical ft of each other: Bed 17 at a 1,500-ft mining depth and Bed 14 at 1,600 ft.

The seams tend to be at shallower depth at the north end of the patch-starting around 800 ft down-dipping toward the south to 2,000 ft.

The trona (hydrated sodium bicarbonate carbonate) beds of Sweetwater County, Wyoming are noted for a variety of rare evaporite minerals. The Green River Formation, is the type locality for eight rare minerals: bradleyite, ewaldite, loughlinite, mckelveyite-(Y), norsethite, paralabuntsovite-Mg, shortite and wegscheiderite. It also has a natural occurrence of moissanite (SiC) and 23 other valid mineral species.

Tata Chemicals North America (TCNA) has been mining and processing trona ore, a mineral that contains soda ash, at Green River, Wyoming since 1968. The Green River facility is located on the 'mile high' prairies of southwestern Wyoming, home to the world's largest reserves of trona ore.

Ore is extracted by room-and-pillar methods, using both Sandvik 780 borer miners and Joy 12HM12 drum-type continuous miners. Roughly 80% of ore production comes from bore mining, with the rest produced by the continuous miners during entry development or borer panel setups.

Normally, two continuous miner crews are assigned to entry development. The CM crews cut rectangular, 18-ft-wide entries to the height of the seam in patterns of three to seven entries. Pillar dimensions vary according to the type of mining and estimated working life of the entry; e.g., main development, CM advance/retreat and borer advance/retreat. Standard pillar dimensions are 80 x 120 ft. Active mining areas generally measure a mile in length by three rooms wide. Three CM crews handle stub-out development ahead of the three borer miners. The general plan for borer mining results in a herringbone pattern with long, thin pillars.

The mine has 180 underground production, maintenance and utility workers, with production crews working 14 days within each 28-day cycle, on an alternating day-and-night shift schedule culminating in an eight-day break. About 40 workers are underground during each ........

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