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• <br />2.05.6(6) <br />PR -12 <br />i9 PPROVEp <br />I1P. /i <br />The Hughes' cabins are both located in limited extraction zones so the <br />mining operation will not have any effect on the cabins. Additionally, the <br />cabins are outside of the projected angle of draw so no damage is predicted. <br />It is not expected that subsidence will affect the stability of old landslides to <br />the extent that their deformations could be renewed. Attention will have to <br />be paid to mining close to the coal outcrop. The Operator will leave one row <br />of development pillars between the outcrop and extracted pillars within the <br />panel. No repairs are currently required, but procedures could be developed <br />if studies show outcrop barrier pillar problems are anticipated. <br />Differential vertical settlement due to subsidence over a short distance could <br />result in local changes in ground surface and slopes. If such changes occur <br />along an ephemeral or intermittent stream channel, the stream's gradient will <br />change. Any gradient change will impact the stream characteristics. In an <br />extreme case, gradient changes may disrupt the flow. Such an event is not <br />probable in topographic conditions of the area where most stream channels <br />are relatively steep. Flow through the drainages could temporarily be <br />affected by a subsidence crack across a stream channel, however, the crack <br />would be expected to heal fairly quickly so the surface drainage pattern <br />would be naturally restored. <br />Very little flow has been recorded for the various ephemeral and intermittent <br />steams in the permit and adjacent area. These streams are expected to be <br />typically dry with flow occurring during spring snowmelt and after significant <br />precipitation events. Therefore, short term disruptions in the flow from these <br />streams should have very little impact on the water budget for Hubbard and <br />Terror Creeks. <br />Hubbard Creek, Terror Creek and the creek in Stephens Gulch could be <br />damaged by subsidence cracks which could cause surface flow to run into <br />the mine below. It may be possible to repair a stream that is affected by a <br />crack. First the flow interrupting crack would have to be located. Then a <br />culvert would be installed to divert the water from the crack. Then the crack <br />would be sealed with a impervious liner or other material. <br />2.05-142- 06/10 <br />