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April 23, 20 10 <br />b) Calculating soils in only the disturbed areas across 2009, versus the entire 51 acre LTSP <br />area which was incorporated in the calculations for TR-40. <br />c) Wind erosion. <br />d) Timing of the various volume calculations - late 2008 (air photo mapping) volume, <br />versus early 2009 (TR-40) volume, versus late 2009 (air photo mapping) volume. <br />e) CAD calculations - following discussions with three other CAD operators, each having <br />20 years experience in running volume calculations from flyover topography [DTM <br />(Digital Terrain Model) files], the overall conclusion is that CAD will have an accuracy <br />rate of 90% to 98%, with good DTM files. When flyover comparisons are done to <br />determine volumes there are always minor differences in the surfaces. It should be noted <br />that a difference of less than 1 inch over a large area can create a difference of 1% to 5% <br />in volumes, and these can be caused by natural occurring events such as weather induced <br />erosion resulting from wind, rain and snow melt, along with grading and compaction, and <br />by minor differences in the flyover data (less than 1 foot), year to year. <br />While the discrepancy is not insignificant, it is suggested that notation be made in the record, <br />and that subsequent year(s) comparisons be undertaken to evaluate whether the differences <br />remain constant, shrink or expand in a manner that warrants further examination. <br />2