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• ~~ <br />Memo to Susan McCannon <br />Tatum Letter of May 11, 1995 <br />page 4 <br />(6) Mrs. Tatum asserts that the Division has "been relying on the fact and/or <br />assurance that no movement has taken place on the railroad". I will briefly <br />clarify my position regarding the Tatums' assertion that their structure has <br />been impacted by coal mine subsidence, by repeating my finding as included <br />in my original memorandum of February 8, 1995. <br />"(1) The Tatum residence is experiencing significant structural <br />deterioration. At some point the level of distress could represent a <br />safety hazard. It would be prudent for the Tatum's to obtain the <br />professional services of an architectural engineer or structural engineer <br />to ascertain the degree of deterioration of the structure, and to develop <br />and implement an appropriate rehabilitation program." <br />"(2) I do not have sufficient expertise or data to determine specifically what <br />phenomena is causing the deterioration of the Tatum's residence. My <br />limited observations allow me to deduce the apparent character of the <br />distress movements. Simplistically stated, the exterior walls are <br />rotating out at their tops. This is consistent with the perimeter of the <br />structure moving downward in relation to the center of the structure." <br />"(3) However, I do have sufficient evidence to conclude that mine <br />subsidence is not the cause of the Tatum residence's observed <br />structural symptoms. Ground subsidence due to mining is a relatively <br />drastic and disruptive phenomena. Further, mine subsidence <br />displacement tends to occur as a progressive directional wave front, <br />which results in displacements with consistent moments. <br />Displacements in the subsurface caused by mine subsidence migrate <br />towards the surface. When the displacement reaches a foundation it <br />applies distorting stresses to the foundation. If the stress exceeds the <br />strength of the foundation, the foundation will fail. The resulting strain <br />of the foundation failure and distortion will, in turn, apply stress to the <br />structure's superstory." <br />"Field stone and mortar foundational walls are extremely brittle and <br />relatively low in shear strength (weak). Because they have no <br />structural reinforcement they have negligible tensile or beam strength. <br />They break and distort easily under applied stress. The mortar <br />disintegrates and the field stone cobbles are displaced. Dry set adobe <br />