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0 0 <br /> The production well heads will be connected with the processing facilities discussed in <br /> Section D-3.6 Nahcolite Surface Processing Facilities by a well field pipeline system. The <br /> pipeline system will be equipped with pressure sensing transducers connected to an alarm <br /> system to detect failures in the system. In addition, an auxiliary 2-inch pipeline will be <br /> connected to select points on the pipeline to permit draining of the pipeline to the 1 to 2 acre <br /> wellfield wastewater evaporation/storage pond. This pipeline and an independent pumping <br /> system will be used to drain the pipeline before relocation or if a pipeline fails. All process <br /> pipelines will be installed above ground to permit regular inspection of the condition of pipe <br /> joints and valves. If leaks occur, a ditch/berm system as shown on Figure C-6 would collect <br /> fluid along the pipeline system to reduce adverse impacts by containing and conveying <br /> liquor in the system to the 1-2 acre wellfield wastewater evaporation/storage pond. All <br /> process pipelines will be installed above ground to permit regular inspection of the condition <br /> of pipe joints and valves. <br /> Hardy and Goodrich (July, 1996) conducted a cavern stability evaluation for the Rock <br /> School Lease Project. Thermomechanical stress analysis were conducted to evaluate <br /> cavern stability. Cavity temperatures were assumed up to 300°F. Cavern growth was <br /> assumed to occur at an approximate rate of 32 foot increase in diameter per year. Due to <br /> the low permeability/porosity of the strata, the rock was assumed to be unsaturated and fluid <br /> pressures within the cavern exert a boundary pressure provided by the weight of a column <br /> of water to the surface. For single cavern stability: <br /> • Evaluation of the structural stability of 125 foot diameter single caverns indicate that <br /> cavern walls and roof will be stable during solution mining and after cooling. In fact, <br /> thermomechanical analysis indicate that cavern roof and wall stability increase after <br /> cooling. <br /> • Only small zones of shear failure were predicted for the 125 foot diameter cavern near <br /> the cavern roof/wall intersection. Analysis of fallout of the zone of failed material did not <br /> indicate a propensity for propagation of failure further into the roof. <br /> • During solution mining some slabbing of the cavern wall will occur. Depths of predicted <br /> slabbing are approximately 8 feet for the 125 foot diameter cavern. However, this <br /> material cannot fall out, because of the amount of insolubles that will nearly fill the <br /> caverns. If the failed material cannot fall out, propagation of failure further into the pillar <br /> is unlikely after mining. <br /> G:\LMW178545.002\Reclamation\Reclamexh.DOC D-28 <br />