2012-03-07_REVISION - M1983194 - Laserfiche WebLink

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NSI pipelines traverse approximately 2 miles of terrain. NSI pipelines are 8" carbon steel lines with manual plug valves. The lines are visually inspected during shiftwise operator well checks. Maintenance is as- needed. Any line that has been inactive for more than one year will be pressure tested with air and any Teaks repaired prior to start -up. Additionally, flow through pipelines may be controlled from the plant operations control room by way of automatic valves. Additional information concerning NSI's facilities may be found in the Natural Soda 2010 Mine Plan. (8) Groundwater Information (a) A map of tributary water courses, wells, springs, stock water ponds, reservoirs and ditches in NSI's area of operations is included as Figure 2. (b) The uppermost Perched Aquifer is a discontinuous "perched" aquifer, forming on tongues of the Green River Formation which may occur within the Uinta Formation. In the area of NSI's operations, occurrences of the Perched Aquifer are noted at depths of between 380 and 570 feet below the ground surface. Information regarding local aquifer systems, including general flow direction and rate, as well as historic hydrologic testing, can be found in Section 5.3 of the Mine Plan (July, 2010). (c) A comprehensive description of the Uinta Formation underlying the NSI processing plant, pipeline trace, and process pond, which includes the Perched Aquifer that rests on the first Green River Formation tongue, can be found in Sections 4.2.3.4 and 4.3.4.1 of the Mine Plan (July, 2010). (d) Areas of minor to moderate fracturing may be located below the NSI lease area and between the depths of approximately 1,300 and 1,650 feet in the Eocene Green River Formation within the Piceance Creek Basin. Refer to Figure 4 -1 found in NSI's 2010 Mine Plan for a map indicating the described area. It is noted that most of the sodium bicarbonate will precipitate out of solution on or very near the ground surface in the event of a spill of NSI's aqueous process fluid, therefore, the potential for any adverse impact to ground waters is minimal to non - existent. This rapid precipitation and crystallization of sodium bicarbonate will occur as the process fluid cools and becomes incapable of retaining higher quantities of sodium bicarbonate in solution. The crystalline sodium bicarbonate would then be raked or scraped up and properly disposed. (e) Section 5.0 of the previously submitted and approved Mine Plan (July, 2010) describes and illustrates in detail the surface and groundwater hydrogeology underlying the NSI lease. In addition, Section 4.3 of the previously submitted Mine Plan (July, 2010) describes and illustrates in detail the geologic strata and fracture systems that have the potential to transmit groundwater. (9) Groundwater Quality Data (a) Three of the four aquifers (Perched, A- Groove and B- Groove aquifers) are considered by the EPA to be Underground Sources of Drinking Water (USDWs) in so far as total dissolved solid (TDS) levels are Tess than 10,000 mg /I. The Dissolution Surface aquifer is not considered a USDW by the EPA. None of the aquifers, however, have a water quality that renders it potable. There is currently no groundwater being used for any purpose within 2 miles downgradient of NSI operations. The only reasonable potential future use for groundwater up to 2 miles downgradient of NSI operations would be for industrial uses similar to the existing NSI operations, as makeup supply water to be used in the solution mining injection process. (b) The following tables (1 -4) contain historical and current data for major analytes for each of the aquifers. Additional information may be found in Section 5 of NSI's 2010 Mine Plan. Daub & Associates, Inc. NSI 2012 EPP Page 8