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• outcrop barrier pillar. This outcrop barrier pillar will prevent the potential crushing, sliding, <br />or other subsidence near the outcrop which could have the potential to initiate or reactivate <br />landslides near the outcrop. It is also recommended that no mining development be <br />conducted in overburden less than 110 feet to prevent the same effect to landslides due <br />to chimney collapse. <br />4.2 PREDICTED IMPACTS ON RESOURCES AND SURFACE STRUCTURES <br />The land under which mining will occur is currently used for limited domestic stock <br />grazing and wildlife habitat. These activities should not be sensitive to the effects of <br />subsidence and are unlikely to be adversely affected directly. However, to the extent that <br />these activities depend on water, there will be a negative impact on them if necessary <br />water sources are disrupted. Subsidence cracks, while open, would pose a danger to <br />domestic stock and wildlife before they are filled and healed by natural processes. <br />Surface water resources consist of stock ponds, and ephemeral and intermittent <br />streams. These should be unaffected by changes in surface gradients or total subsidence <br />resulting from development of a subsidence profile. The ponds could be damaged and <br />• drained by a subsidence crack that would occur directly below the pond. The probability <br />of such an event is very low and if so the pond could be easily repaired. <br />Differential vertical settlement due to subsidence over a short distance could result <br />in local changes in ground surface and slopes. If such changes occur along an ephemeral <br />or intermittent stream channel, the stream's gradient will change. Any gradient change will <br />impact the stream characteristics. In an extreme case, gradient changes may disrupt the <br />flow. Such an event is not probable in topographic conditions of the area where most <br />stream channels are relatively steep. Flow through the drainages could temporarily be <br />effected by a subsidence crack across a stream channel, however, the crack would be <br />expected to heal fairly quickly so the surface drainage pattern would be naturally restored. <br />Very little flow has been recorded forthe various ephemeral and intermittent steams <br />in the permit and adjacent area. These streams are expected to be typically dry with flow <br />occurring during spring snowmelt and aftersignificant precipitation events. Therefore, short <br />term disruptions in the flow from these streams should have very little impact on the water <br />budget for Hubbard and Terror Creeks. <br />• <br />- 31 - 02/01 <br />P~-~ <br />