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May 11, 2011 Page 17 <br />Room - and - pillar entries and panels may be developed underneath timber frame structures with <br />no pillar extraction within the buffer zone estimated using the Pennsylvania Subsidence Act <br />guideline. <br />The pillar sizes for development mining within the buffer zone are to be determined using <br />appropriate methods such as ARMPS so that they have stability factors of at least 1.5. In case <br />the workings directly beneath the timber frame buildings are to be utilized for water storage, the <br />stability of the developed pillars is to be evaluated on a site - specific basis. <br />4.13.2 Timber Frame Building Monitoring Plan <br />To ensure that the control plan is effective, AAI recommends the following monitoring <br />plan: <br />• Accurate location and elevation information of the buildings must be collected prior to <br />mining. <br />• The owner(s) /dweller(s) 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 two appropriately positioned survey monuments each should be established <br />around each structure. <br />• Annual surveys should be conducted for the operating life of each structure. <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 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 owner(s) 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 />Agapito Associates, Inc. <br />