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Computer-Aided Draftine Svstem <br />The 1994 AHR Report initially addressed CEC's concerns relative to <br />comparison of contouring between the former 1993 and 1994 mapping <br />activities. Since the reliability of the map work is key to most other CEC <br />activities relative to reclamation, it is important to build reliability into this <br />database. This is the sixth year the Computer-aided Drafting (CAD) system <br />has been used for CEC mapping purposes. As with previous years, a review <br />of the contour discrepancies (year to year) has been conducted. This <br />continuing review affirms and reinforces statements made in the 1994 AHR <br />Report, that the discrepancies, as noted, were the result of earlier mapping <br />techniques. CEC believes that these errors have been substantially reduced <br />through the continued use of the CAD system. Our comparison of the 1999 <br />mapping data to the previous four years work products suggests only a few <br />questionable contour differences, none significant enough to call into question <br />the modeling technique. <br />• Software Explanation <br />SOFTDESK/ADCADD SOFTWARE CIVIL/SURVEY, with <br />EARTHWORKS and DIGITAL TERRAIN MODELING MODULES is <br />used to compare the 1994 tluouglr 1998 site elevation data with the most <br />recent 1999 site elevation data. This software program is used to first <br />calculate the position and elevation of each elevation point and points along <br />each elevation contour and then generates a computer model representation of <br />the ground surface. The computer-generated ground surfaces are then used in <br />determining airspace and soil volumes and in performing cut/fill calculations. <br />The average end-area method is used in all volume calculations and the <br />prismordial grid method is used in all cut/fill calculations. <br /> <br />A[iR-1999 -118- <br />