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electronic distance measuring device (EDM). <br /> The method of the monitoring surveys involved side shots from the <br /> established control points to the monitoring points. Horizontal and vertical <br /> angles were measured in both the erect and Inverted aspects. Slope distance was <br /> determined to the nearest 0.01 ft by taking the average of three EDM readings. <br /> c. <br /> 4.0 RESULTS <br /> The results of the control survey are tabulated In Table 4.0-1 as <br /> coordinates and elevations of the TP-serles control points. The results of the <br /> monitoring surveys are tabulated in Tables 4.0-2, 4.0-3 and 4.0-4 as coordinates <br /> and elevations for the MC-series monitoring points for the 1981 , 1982 and 1983 <br /> surveys, respectively. <br /> 5.0 CONCLUSIONS <br /> Table 5.0-1 presents the changes In elevations for each MC-serles monitoring <br /> point as a function of time. The determination of subsidence was based on a <br /> negative change in elevation of more than 0.1 ft. This value of 0.1 ft was ' <br /> determined from the vertical angle accuracy requirements of a Third Order, Class <br /> 11 survey. This standard indicates a maximum allowable spread of 20 seconds <br /> between vertical angle observations of the same point. Based on an average <br /> horizontal distance of 2950 ft for the eight closest monitoring points, this <br /> equates to a maximum variation In the calculated change in elevation of 0.1 ft. <br /> Monitoring point MC#1 was excluded from the average horizontal distance <br /> calculation because the magnitude of its horizontal distance was about 2000 ft <br /> greater than that of the next longest horizontal distance. inclusion of the <br /> horizontal distance for MC11 would yield an acceptable spread of 0.12 ft In the <br /> 3 <br />