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• III IIIIIIIIIIIII III • <br />Memo to Dan Mathews <br />Nat King Coal's Subsidence Monitoring <br />page 2 <br />constitute a hazard to wildlife, domestic animals and humans using the <br />surface, particularly if the cracking worsens significantly. However, the <br />applicant committed to effecting repairs on page 19 of section 2.05.6 of the <br />permit application. <br />In my opinion it is not warranted at this time to significantly modify the <br />approved visual subsidence monitoring program. I recommend that we inform the <br />operator that we desire to have them continue quarterly surveying of the <br />subsidence monuments installed above Panels 2 and 3 East for the next year. <br />Further, we should require them to include the survey results in next year's <br />quarterly subsidence monitoring reports. When subsidence has ceased we can <br />allow them to discontinue surveying the monuments. <br />I would expect the subsidence tension cracking to abstract with time. <br />Slumping of the walls of the cracks, and infilling of sediment by wind and <br />water, should cause the cracks to be obliterated with time. I recommend that <br />we observe the cracks during inspections. If the cracking develops to the <br />point of constituting a hazard to wildlife, domestic animals or humans, we <br />should require the operator to fence the cracks or to fill them. Failing the <br />existence of such a hazard, I don't believe a control plan or remedial action <br />is warranted. <br />cc: Mike Savage <br />