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October 11, 2011 <br />Page 24 <br />• The retreat plan should be re- evaluated to ensure that operations will not further damage <br />the structure in question. <br />4.11 Roads <br />4.11.1 Unpaved Road Subsidence Control Plan <br />The majority of the roads that are likely to be affected by mining- induced subsidence are <br />unpaved. Although no damage criterion could be found for unpaved roads, the allowable levels <br />of horizontal strain for paved roads are 1 -3 millistrain and allowable slopes are 0.5% to 1%. <br />These levels of ground disturbance should not affect unpaved roads as intensely. Therefore, <br />unpaved roads may be fully undermined with appropriate monitoring, as outlined below. <br />4.11.2 Unpaved Road Monitoring Plan <br />To ensure that the control plan is effective, AAI recommends the following monitoring <br />plan: <br />• The road owners should be informed as mining approaches and data generated during <br />monitoring should be shared with them. <br />• Visual monitoring should be performed on the roads weekly as long as the retreat line is <br />within a 10° vertical offset angle. Any appearance of cracks, heave, slumps, or steep <br />gradients in the roads should be noted. <br />• Structural anomalies reported by the surface owner(s) will.be investigated. <br />4.11.3 Worst Possible Consequences of Damage to Unpaved Roads <br />Horizontal strains in excess of the allowable strain levels could create cracks, heave, <br />slumps, significant changes in gradient, etc. All of these factors could deteriorate the road <br />surface, possibly adversely affecting driving conditions or road utility. <br />4.11.4 Unpaved Road Damage Mitigation Plan <br />In case monitoring indicates onset of damage or potential for damage to unpaved roads, <br />the following mitigation plan should be adopted: <br />• Appropriate personnel at mine and regulatory authorities, as well as the owners of the <br />road, should be informed in case anomalies are observed that may indicate an affected <br />road segment. <br />• Re- grading should be applied to affected road segments. <br />• The retreat plan should be re- evaluated to ensure that operations will not further damage <br />the road segment in question, or an agreement should be reached with the road owner that <br />such damage is acceptable as long as it is repaired. <br />Agapito Associates, Inc. <br />