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The objective of this procedure is to extract as much of the TI Bed as possible and to <br /> promote rubblization by collapsing the undercut. The anticipated cavern configuration after <br /> the undercut rubblization is shown in Figure 4-6. After collapse of the TI Bed, the roof pad <br /> will be moved upward to near the top of the Greeno Bed shown in Figure 4-1 (approximately <br /> 2,485 feet below ground surface). A similar undercut will be made in the Greeno Bed, again <br /> by continuing to solution mine with 300OF weak brine. The cavern will continue to rubblize <br /> as the nahcolite saturated solution flows to the surface processing facilities. <br /> As the cavern contents rubblize and the nahcolite is removed from the Greeno Bed, the gas <br /> roof pad may be raised to the top of the Love Bed (approximately 2,100 feet below ground <br /> surface). This Bed then will be solution mined like the TI and Greeno Beds. The anticipated <br /> typical cavern is shown in Figure 4-7. Over time the central portion of the cavern will be <br /> devoid of nahcolite, but new material at the perimeter of the cavern will produce additional <br /> nahcolite for solution mining until production rates are no longer economical to continue. <br /> During the injection of the dilute sodium bicarbonate solution, recovery head pressures will <br /> be approximately 300 psi and the casing seat pressure will be approximately 1,000 psi. <br /> During the undercutting operation of the wells, sodium bicarbonate injection flow will be up <br /> to 400 gpm; during full production the flow will be approximately 100 gpm for each cavern. <br /> This will result in the diameter of a cavern increasing approximately 0.1 feet/day with an <br /> ultimate cavern diameter of up to approximately 225 feet and approximately 600 feet in <br /> height. This also will result in approximately 125 foot pillars between the cavities. <br /> If during solution mining there are well failures, the remedial action will depend on the <br /> specific circumstances of the failure. If the failure is associated with the production tubing, <br /> the pipe will be pulled and repaired, as appropriate. If the outside casing fails, corrective <br /> actions would include spray coatings on the interior of the casing for small leaks; in the <br /> event of major leaks or a break, a new well casing could be emplaced inside the old casing <br /> and cemented in place. The affected well then would be tested for integrity and placed into <br /> operation following confirmation of the integrity test. <br /> G:LLMW 78545.002%MinePlan%MINEPLAN.DOC 4-12 <br />