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• <br />• <br />APPENDIX D <br />March 2000 -10- 993-2099.150 <br />of the vertical holes were drilled to depths up to about 150 feet, compared with 100 feet <br />for the inclined holes. Even wide spans that were indicated on the drawings to have been <br />excavated relatively deep below ground surface were exploratory drilled in this manner in <br />case prior caving upwards had already occurred. <br />All drilling was undertaken using a reverse circulation rig with a hammer bit. The <br />objective was to locate voids and identify "soft" zones that might represent backfill or <br />caved material. Golder representatives with previous experience in investigating the <br />Phase III area were on site full time to locate the drillholes, oversee the drilling and <br />document the field investigation. The quality of the drilling was enhanced by the <br />experience of the drilling company and drilling crews in having drilled the Phase III site <br />area previously and many other areas of the mine site where underground workings were <br />present. <br />Approximately 100 exploratory holes were drilled at approximately 80 drill hole locations. <br />A summary of the drilling details for each hole, including distances along the holes that <br />excavations were encountered, is presented in Table 2. The location of the holes and the <br />orientation and lateral extent of the inclined holes are shown on Drawing Nos. 5 and 6. <br />The location of the voids that were encountered by the drilling are also shown in Drawing <br />Nos. 5 and 6. <br />4.0 CONCLUSIONS FROM EXPLORATORY INVESTIGATIONS <br />Site observations and the results from the exploratory excavation and drilling programs <br />indicate that remediation is required for: <br />? isolated shafts and other isolated excavations carried out on surface <br />(e.g., shallow surface mines and adit portals) <br />E <br />I-M2MFMAL RMAMMA"D.DM <br />Golder Anociotes