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E Y <br />CO <br />C CO <br />E 100 ft. to protected <br />75 ft. setback to P <br />accommodate slouahino structure or boundary <br />water line <br />As illustrated above, dredge mining would cease when the dredge approaches within 175 feet of the structure or <br />boundary from which the setback is established. Similarly, in the case of a 25 foot setback, as proposed for the <br />gastoil pipelines, and if the pit depth is again 60 feet, the mining limit would be 100 feetfrom the protected <br />structure or boundary. This approach to the establishment of mining setbacks can be described by the following <br />expression: <br />(setback distance) + [125 x (pit depth)] = distance mining may occur from a protected structure or boundary <br />This approach to the establishment of setbacks is conservative and is acceptable to the Division without any <br />further analysis required by the Applicant. However, this type of requirement may tend to create complications <br />for the pit operator in the long term. If the pit foreman and other essential personnel are not fully aware that the <br />mining limits are established by a formula depending on maximum mining depth, inadvertent noncompliance <br />with the reclamation permit may result. The Division suggests that the Applicant establish the mining limits in <br />advance based on the bore hole data and anticipated mining depths throughout the pit, commit to the mining <br />limits so established, and mark the mining limits in the field in advance of dredge mining at the pit perimeters. In <br />other words, make the mining limit, as it is labeled in the above diagram, an enforceable permit requirement that <br />is dearly described and illustrated in the application. <br />In summary, the application discusses two approaches to protection of structures within 200 feet of the affected <br />land: (1) obtain agreements with persons having an interest in the structures, (2) setback a specified distance <br />from critical structures and boundaries assuming that the pit walls will slough to 2Y: h : 1 v. Either approach is <br />acceptable to the Division, but the setbacks required must be dear, unambiguous, and enforceable. It is further <br />• Page 2 <br />1 <br />IIIIII VIII VIII VIII VIII VIII IIII IIII <br />008290 <br />