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e <br /> The production well heads will be connected with the processing facilities discussed in <br /> Section 4.6 Nahcolite Surface Processing Facilities by a well field pipeline system as shown <br /> on Figure 4-8. The pipeline system will be equipped with pressure sensing transducers <br /> connected to an alarm system to detect failures in the system. In addition, an auxiliary <br /> 2-inch pipeline will be connected to select points on the pipeline to permit draining of the <br /> pipeline to the 1 to 2 acre wellfield wastewater evaporation/storage pond. This pipeline and <br /> an independent pumping system will be used to drain the pipeline before relocation or if a <br /> pipeline fails. If leaks occur, a ditch/berm system would collect fluid along the pipeline <br /> system and reduce adverse impacts by containing and conveying liquor in the pipeline <br /> system to the 1 to 2 acre wellfield wastewater evaporation/storage pond. All process <br /> pipelines will be installed above ground to permit regular inspection of the condition of pipe <br /> joints and valves. <br /> Hardy and Goodrich (July, 1996) conducted a cavern stability evaluation for the Rock <br /> School Lease Project, a copy of which is included in Exhibit C. Thermomechanical stress <br /> analysis were conducted to evaluate cavern stability. Cavity temperatures were assumed <br /> up to 300°F. Cavern growth was assumed to occur at an approximate rate of 32 foot <br /> • increase in diameter per year. Due to the low permeability/porosity of the strata, the rock <br /> was assumed to be unsaturated and fluid pressures within the cavern exert a boundary <br /> pressure provided by the weight of a column of water to the surface. For single cavern <br /> 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:IM1M78545.002%MinePlanVAINEPLAN.000 4-15 <br />