The deposit type of the Sevier Playa is a terminal lakebed (playa) brine deposit. The brine deposit is sedimentary in origin and composed of the natural concentration of mineral salts in groundwater found in the Playa. The brine is contained within the unconsolidated Playa sediments, composed primarily of clay and marl, a lime or calcium-rich clay. While the sediments may play a role in the mineral occurrence, development efforts to date have focused primarily on the mineral content found in the brine. The extractability of the brine Mineral Resource and the interaction between the brine mineralization and the potential for recharge by water flowing through the Playa sediments is part of this investigation, and an integral part of the determination of total extractable Mineral Reserves of SOP and other potential mineral compounds.

Composition of the thin salt crust covering the Playa consists of evaporite minerals and is approximately 3 to 4 inches (7.6 to 10.2 centimeters) thick, ranging up to as much as 18 inches (45.7 centimeters) in areas, as determined from drilling and augering data. Evaporite minerals forming the crust tend to be zoned on the Playa surface with halite (NaCl) being the dominant mineral in the center of the Playa, followed by glauberite (Na2Ca(SO4)2), and then gypsum (CaSO4) near the Playa shore (Godbe, 1984; Rasmussen, 1997).

Soluble salts, in the sediment-hosted brine, are the target mineralization of current development work. T ........

The proposed mining method for the collection of naturally- occurring brine from the sedimentary basin of the Sevier Playa involves a combination of stepped extraction trenches and drilled wells to collect the subsurface brine. The brine is conveyed into a series of solar evaporation and concentration ponds located on the surface of the Playa. The larger pre-concentration ponds are located in the northeastern portion of the Sevier Playa with the production ponds located in the southern portion of the Sevier Playa, with adjacent TMAs. Refer to the sections that follow for discussions on mine layout, extraction methodology, and construction methods, as well as supporting infrastructure.

In general, the mine design consists of the following four major components:

- Brine extraction system consisting of canals, trenches and wells
- Recharge system consisting of canals, collectors and trenches
- Series of evaporation ponds
- TMA.

The extraction and recharge trenches are placed throughout the Playa and their spacing and direction varies depending on permeability, conductivity, and/or concentration of the brine. The Playa is divided into mining units, referred to as BMUs. There are 21 BMUs; BMU1 to BMU11, and BMU13 to BMU22. Each BMU unit consists of extraction trenches, recharge trenches, recharge collectors, and extraction wells.

The extraction trenches within each BMU are connected to the extraction canal to facilitat ........

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