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Ad valorem tax. A tax “according to value.” Property tax is an ad valorem tax. Ad valorem taxes are among the types of tax revenue that potash mines bring to the state and county.

Aquifer. A water-bearing layer of rock or unconsolidated materials (gravel, sand or silt) from which groundwater can be usefully extracted by a well. In the Holbrook Basin, the most significant aquifer is the Coconino Aquifer. It is in rock layers, primarily Coconino Sandstone, above the Holbrook salt layers and the potash deposit. It provides the water supply for most municipal, domestic, agricultural and industrial uses in the area.

Baseline studies. Investigations that determine the current state of an area and establish a reference for future studies. Baseline studies are conducted as part of permitting processes. They provide information for decision-making and for future reference to measure changes caused by a development project. Baseline studies are an essential foundation for future monitoring studies, so that differences from a pre-development state can be accurately determined.

Brackish water. Water that has higher levels of total dissolved solids (TDS) than fresh water, but less than saline water. The term is often applied to water that has more than 1,000 parts-per-million TDS, but less than 10,000. The water is brackish in parts of the Holbrook Basin, especially along the Little Colorado River, and near Holbrook and St. Johns. North of the Little Colorado, the groundwater is usually saline, containing more than 10,000 TDS. Much of the potash deposit, but not all of it, is underlain by saline parts of the Coconino Aquifer. The dissolved solids in brackish water in the Coconino Aquifer are dominated by sodium chloride (table salt) in many areas, but sulfates are dominant in other areas.

Brine. Water containing large amounts of dissolved solids, usually more than the 30,000 TDS in sea water. Brines are often found in very deep groundwater that is in contact with evaporites.

Carnallite. A mineral consisting of hydrous potassium-magnesium chloride. Carnallite is a significant source of potash that is sometimes found with sylvite and other evaporite minerals.

Continuous miner. A machine with a large rotating steel drum equipped with tungsten carbide teeth used to cut the working face in underground mines, such as potash and coal mines. Continuous miners operate in a room-and-pillar system, using conveyors to transport the ore to the mine shaft. Remote controlled continuous miners and robotic versions controlled by computers are becoming increasingly common.

Dewatering. Pumping of groundwater from a mine to keep mine operations dry.

Direct employment. Jobs directly related to a development project, such as a mine.

Engagement. A process by which stakeholders and project proponents build and maintain constructive relationships over the life of a project. Strategies vary depending on features of the project and the context, and can include community forums, focus groups, work groups, electronic media, and other techniques. Engagement with local communities and the broader stakeholder base is considered essential for effective risk management and to obtain “net benefits” for the community.

Evaporites. Mineral deposits that remain when sea water or lake water evaporates in an enclosed basin. In the Holbrook Basin, the most common evaporites are halite (sodium chloride, NaCl) and anhydrite (calcium sulfate, CaSO4). Sylvite, sylvinite, carnallite and polyhalite are potassium-bearing minerals that are also found, along with gypsum and other minerals.

Fracking. The propagation of fractures in a rock layer caused by the presence of a pressurized fluid. The process is also called hydraulic fracturing or hydrofracking. In solution mining for potash, fracking can be used to increase exposure of injected fluid to potash, increasing yield. In that case, the pressurized fluid that is used is water. It does not contain other chemical ingredients. The critical factors for successful use of fracking in potash solution mining include the integrity of the well bore and the ability to predict and control the location and extent of fracturing of the ore body and nearby layers.

Fresh water. A natural source of water that is not salty and that is suitable for drinking. EPA standards for public drinking water are less than 500 TDS as the Primary Standard; more than 1,000 TDS is considered unacceptable.

Greenfield. A site that is being considered for commercial or industrial uses that has not previously been developed. Greenfield is often contrasted with brownfield – a site previously used for industry.

Groundwater. Water beneath the earth’s surface, often found between saturated soils and rocks that supplies water to wells and springs, and that is often connected with surface water sources such as rivers and streams. In the Holbrook Basin, groundwater is found in layered aquifers beneath the ground surface. The primary aquifer that is used for the water supply is the Coconino Aquifer. Wells near Pinetop-Lakeside and Springerville-Eager are supplied by water inyounger sandstones and volcanic rock layers.

Halite. A mineral form of sodium chloride, commonly known as table salt. Halite comprises much of the Holbrook Basin. It is the evaporite mineral that is most readily dissolved by water, and sodium chloride is the dominant chemical compound in much of the brackish groundwater in the Holbrook Basin.

Horizon. An identifiable layer of rock that can be traced over a large area. Individual potash beds are referred to as horizons.

Indirect employment. Jobs created by the businesses that supply goods and services to an enterprise, such as a potash mine.

Infrastructure. Rail spurs, roads, gas pipelines, power lines and substations that are required to support an enterprise, such as a potash mine.

Leaching. Natural process by which water-soluble substances are washed out of tailings, wastes or other materials.

Mill. The facility where potash is separated from salt and insoluble materials, and refined to produce a salable product (bulk fertilizer). Processing facilities for potash are also referred to as beneficiation plants, flotation plants and refineries.

Mitigation. To offset or reduce known impacts or risks to a historic, cultural, economic or natural resource.

Monitoring. The collection and reporting of data on environmental or socio-economic factors, used for comparisons over time to determine the impact of an enterprise. For potash mines, environmental monitoring programs are often put in place to measure factors such as water quality, the water table, land surface subsidence, seismic events and air quality. Socio-economic monitoring programs often measure local employment, local sourcing and procurement, safety, and social investments.

Net Benefits. Expected benefits outweigh anticipated costs and risks. Net benefits for the local area are considered by many mining-industry organizations to be essential to successful operation of a mine over the long term.

Ore. A naturally occurring mineral from which a valuable constituent can profitably be extracted. The potash that can profitably be extracted from a mine is called the ore.

Potash. Any of several naturally-occurring compounds containing potassium, especially soluble compounds that are good sources of potassium, such as potassium chloride, potassium oxide, and potassium sulfate.

Room and pillar mining. A mining technique often used in coal mining and underground potash mining, where the mineral is extracted forming “rooms” separated by “pillars” that are left intact to support the roof of the mine.

Royalty revenue. Payments from one party to another for use of an asset, often in the form of a percentage. Royalty revenues are due to governments for mining on public lands.

Stakeholder. Someone or a group that is impacted by a proposed project over the anticipated life of the project. Stakeholders include local communities, governments, investors, civil society, employees, suppliers and others with an interest in the project. Stakeholders are distinct from project proponents. A proponent may have a stakeholder engagement strategy for identifying, informing and working with stakeholders over the life of the mine.

Subsidence. Depression of the ground surface. In underground or solution mines, subsidence can be caused by sinking or collapse of the overlying rock and soil layers above the mine resulting from the sinking of a mine roof or by dissolution of evaporite layers due to water infiltration. Whereas subsidence is typically gradual and minor, in rare cases it can be sudden and catastrophic, causing sinkholes and fissures. In the Holbrook Basin, especially near the Holbrook Anticline, there are sinkholes and fissures thought to be caused by natural dissolution of the evaporite layers in the Supai Formation, resulting from contact with groundwater. Management of subsidence involves stakeholder collaboration, careful mine planning, preventative measures and monitoring.

Supai Formation. Geologic layers beneath the Coconino Sandstone that contain the evaporite layers of the Holbrook Basin, including the potassium-bearing evaporites, primarily sylvite.

Sylvinite. A mineral consisting of halite (sodium chloride) and sylvite (potassium chloride).

Sylvite. A potassium-bearing mineral that is the most significant source of potash worldwide and in the Holbrook Basin.

Tailings. Materials left over after the valuable component of ore is separated from other components. Potash mine tailings primarily consist of sodium chloride (salt). Potash mines have salt tailings piles. The salt may be sold or given away for industrial uses, such as for roads, if the freight costs are greater than the value of the salt. Environmentally-safe handling of tailings, including rehabilitation of tailings areas after mine closure, are important mine activities and can involve significant liabilities and costs.

Total dissolved solids (TDS). The level of total dissolved solids in naturally-occurring water is a primary measure of water quality. Typical chemical constituents are sodium, chloride, calcium, sulfate, magnesium, and bicarbonate. In the Coconino Aquifer above the potash deposit, the levels of TDS vary greatly from one area to another, ranging from fresh water with very low levels, to brackish water and brine with levels comparable or higher than the levels of dissolved solids in sea water. The dissolved solids in the Holbrook Basin are thought to primarily originate from dissolution of evaporites in the Supai Formation beneath the Coconino aquifer, and from some leakage from the Moenkopi Formation above the Coconino Aquifer.

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