The quickest method of checking for differences between drillhole collars and topographic surfaces is to import a fi le of the drillhole collar coordinates as a Free Format Survey Import fi le. Use the Blast Pattern Editor (BPE) to calculate the distance to the topographic surface. Once you have this data, the fi le can be exported in SRG format for viewing in Microsoft® Excel.

The drillhole collar fi le can be a Form Export created in acQuire™ or it can be created using P20701.DAT (the Dump Assays to ASCII proce-dure). Import the drillhole collar fi le using Free Form Survey Import. The Free Form Survey Import can use character separators or width separators. If acQuire™ Form Export created the fi le, it will be a CSV (character separated value fi le). In this case the character is a comma (‘,’).

The goal of the import is for each collar point to have the same drillhole name as the element name. To do this, assign the drillhole ID column as the Ele-ment Name, the Easting column as X, the Northing column as Y, and the Elevation column as Z.

By clicking on the OK button, the next portion of the import process appears. In this panel, click on the Save Point ID’s box. The combination of the two import panels is required.

The next step is to set the object into Edit mode by left clicking on the highlighted object in the Data Manager window, then right-click and select Edit. Then start the BPE. Since the drillhole collar object was in Edit mode, the BPE as the grid design uses it and the points are read in. Click on Edit | Select Allin the BPE to select the drillhole collars, then click on the Calculate length(s) to surface button and use the Objects

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Calculating the Difference Between Drillhole Collars and the Topographic Surfaces

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Calculating the Difference Between Drillhole Collars and the Topographic Surfaces continued from page 9)Contents Browser button (circled in red) to select the triangulated topographic surface.

After you have selected the topographic surface click Apply and the distance from the drillhole collar to the surface will be calculated along with the azi-muth and dip. If the dip is negative the drillhole collar is above the topographic surface, if it is positive, the drillhole collar is below the topographic surface.

To export the information, click on the Defaults tab in the BPE. Click the SRG output format. If you want the absolute distance select Start point and length. If you want to know distance above or below, select Start and end points.

Exit the BPE and open Microsoft® Explorer. Rename the exported fi le from *.SRG to *.CSV. Double-clicking the fi lename will launch Microsoft® Excel. If you selected the Start point and length

option, you can sort the exported files using decreasing values in the length column. The length column is the H column and the drillhole name is in the F column.

If you selected the Start and end points, create a new column and populate it with the differences between the start elevation and end elevation, then sort using decreasing values in this column.