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SUBSIDENCE I•IONITORINf, REPORT <br />The information presented in this report is based on survey data obtained <br />in November, 1983. A trigonometric survey method was used to compile the <br />raw data. A systematic error of plus or minus 0.15 feet can be <br />anticipated for survey points on rotas A through E. During the third <br />quarter of 1984 a high order differential survey will be used to determine <br />the maximum subsidence. <br />A minimal amount of surface subsidence has occurred since the last <br />quarter. The maximum subsidence for each row is as follows: <br />Row Subsidence (flaximum) <br />A 2.9 feet <br />B 4.6 <br />C 0.3 <br />D 4.2 <br />Predicted Subsidence <br />2.2 feet <br />3.6 <br />4.0 <br />The mar.imum subsidence measured is slightly greater than the predicted <br />subsidence using the Abel and Lee equations for subsidence. The <br />cross-sections for the above rows are presented on dt•a~•iing EEC-83016-C. <br />The elevation differentials determined for ro~as E and f" can be attributed <br />to the systematic error involved when making a trigonometric survey. <br />Underground investigations indicate that no caving or pillar deformation <br />has occurred in the area of influence of rows E and F. <br />