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• <br />March 2000 <br />APPENDIX D <br />-4- <br />993-2099.150 <br />3.0 SCOPE OF INVESTIGATION <br />The main activities that were undertaken by Golder to assess the current stability of the <br />Phase IV area and to provide recommendations to remediate the foundations were as <br />follows: <br />? A detailed review was undertaken of all of the available historical <br />records, including the historical mining plan maps filed at the CC&V <br />offices, in Victor, Colorado. <br />? A detailed surface reconnaissance program was undertaken and the <br />characteristics of the surface disturbance features were photographed and <br />documented. <br /> <br />? Selected surface disturbance features which had exhibited characteristics <br />suggesting deeper level workings (i.e., conical shaped mine with <br />adjacent overburden piles of sufficient magnitude, evidence of timbering <br />support, feature excavated into bedrock, etc.), were excavated to allow <br />more detailed inspections to be undertaken by Golder's site engineer. <br />? A drilling program was undertaken to locate excavations beneath the <br />ground surface that might adversely impact the stability of the <br />foundation. <br /> <br />In the Phase III report, it is indicated that "For the prevailing conditions, and stopes that <br />are less than 10 to 12 feet wide, the stability of the crown pillar should be acceptable if the <br />bottom of the pillar is more than 50 to 60 feet below surface". This makes allowance for <br />15 feet of surficial soils overlying the rock, which is the maximum overburden thickness in <br />the Phase III area. In some of the Phase IV area, the thickness of the overburden is greater <br />than 15 feet, and in these locations drilling targets were set at greater depths so that <br />surficial soils do not contribute to the stability of the pillar above the mined openings. <br />1:\991 OMINAL RMWraMA"D.DDC Golder Associates