Laserfiche WebLink
October 11, 2011 <br />Page 28 <br />• The owners and/or dwellers of these buildings should be informed as room - and - pillar <br />development approaches, and data generated during monitoring should be shared with <br />them. <br />At least one survey monument should be established around each of the above - mentioned <br />buildings, and weekly survey data should be collected as the pillar development line <br />reaches a 10° vertical offset angle, until the underground development passes beyond the <br />10° vertical offset angle. Weekly survey data should also be collected as long as the <br />pillar retreat line is within a 25° vertical offset angle. Annual surveys should be <br />conducted thereafter. Visual reconnaissance of the ground surrounding the buildings <br />should also be performed simultaneously for any sudden appearance of cracks, heaves, <br />and depressions. The buildings also need to be monitored for cracks in the walls, <br />jammed doors /windows, cracked/heaved floorings and other pertinent damages. <br />• Structural anomalies reported by the surface owner(s) will be investigated. <br />4.13.3 Worst Possible Consequences of Damage to Timber Frame Buildings <br />Subsidence - induced damages to timber frame buildings may be classified into three <br />categories architectural, functional, and structural— depending on the levels of ground <br />disturbance. Architectural damage may mean small cracks in the plaster and sticking of doors <br />and windows. Functional damage could bring about instability of some structural elements, <br />jammed doors and /or windows, broken window panes, and restricted building services. <br />Structural damage may render the structure unsafe for habitation, and possibly lead to collapse, <br />requiring complete rebuilding or restoration. <br />4.13.4 Timber Frame Building Damage Mitigation Plan <br />In case monitoring indicates the onset of damage or potential for damage to timber frame <br />buildings, the following mitigation plan should be adopted: <br />• Appropriate personnel at mine and regulatory authorities, as well as the owners of the <br />building, should be informed in case anomalies are observed that may indicate an <br />affected building. <br />Remedial techniques such as trenching, shoring, and structural reinforcement should be <br />applied to restrict further damage to the structures. <br />• The room - and - pillar development plan should be re- evaluated to ensure that operations <br />will not further damage the structure in question. <br />4.14 Purgatoire River Alluvial Valley Floor <br />4.14.1 Alluvial Valley Floor Subsidence Control Plan <br />The current mining plan under the Purgatoire River and associated alluvial valley floor <br />are development -only workings and do not have any retreat panels. The extraction ratio is also <br />planned to be less than 50% for these workings. Disturbed area boundaries and stream buffer <br />zones have been clearly marked and will be maintained in accordance with Section 4.02 and 4.06 <br />Agapito Associates, Inc. <br />