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i • <br />fluid normally injected to determine the instantaneous <br />shut in pressure (ISIP) and formation breakdown <br />pressure, may request a change in the maximum injection <br />pressure from the Director. <br />Inlet pressures proposed are estimated to result in <br />pressures at the mining interval that would be less <br />than the formation fracture pressure. Formation <br />testing performed by others in the Piceance Creek Basin <br />(below the Dissolution Surface) resulted in fracture <br />gradients of approximately 1 pounds per square inch <br />gage (psig) per foot of depth. This fracture gradient <br />is supported by American Soda's operating data for <br />solution mining well 20-3. In December 1997, inlet <br />pressures for test well 20-3 (which has a surface <br />elevation of 6,230 feet M.S.L. and a minimum depth to <br />the top of the cavity of 1551 feet) were maintained at <br />approximately 600 to 700 psig in a preheated, developed <br />cavity for one week without causing fractures. <br />For commercial operations, the inlet pressure will <br />range from 300 to 700 psig at the surface. Lower inlet <br />pressures shall be used during startup to ensure <br />against fracturing. Fracturing a cavity would cause <br />the solution mining operation to cease because pressure <br />could not be held in the cavity and production fluid <br />could not be extracted. Higher inlet pressures will be <br />used once the cavity has been adequately heated because <br />thermal stresses (induced in confined rock by increased <br />temperature) will allow for higher pressures without <br />fracturing. Formation fracture testing is not planned <br />for the immediate future, but may be conducted during <br />commercial operations. If testing is conducted, <br />according to the EPA Guidance the results shall be <br />provided to the EPA, and inlet pressures will be <br />adjusted if warranted. <br />5. Infection Volume Limitation. There is no limitation <br />on the number of barrels of fluid per day (BFPD) that <br />may be injected into the solution mining well(s). The <br />volumetric flow into and out of each well is currently <br />anticipated to be in the range of 20 to over 200 <br />gallons per minute, but it could be higher. <br />6. Injection Fluid Limitation. The injection fluid is a <br />combination of the following fluids having a total <br />volume equal to the quantity needed to produce brine at <br />EPA FINAL Area Permit No. C03858-00000 <br />Page 18 of 164 <br />