Laserfiche WebLink
PERMIT #: M- 1977 -193 <br />INSPECTOR'S INITIALS: TC1 <br />INSPECTION DATE: June 20, 2013 <br />OBSERVATIONS <br />The purpose of this inspection was to discuss highwall stability as it relates to the Amendment 5 (AM -05) <br />application with respect to the site geology, long term operations and closure. Tim Cazier, Tony Waldron and <br />TC Wait represented the Division of Reclamation, Mining and Safety (Division). Mr. Randy DiLuzio (Tezak <br />Heavy Equipment) and Mr. Ken Klco (Azurite, Inc) represented the Operator. Ms Stephanie Carter represented <br />the Bureau of Land Management (BLM). <br />The Aggregate Source Pit is located in Fremont County, approximately 1.5 miles west of Canon City. The <br />access road is about 400 feet west of the intersection of U.S. Hwy 50 and Tunnel Drive. <br />Site Meeting: <br />All parties met in T.H.E.'s conference room to discuss the benching sequence (20 -foot wide by 40 -foot high) in <br />the mine plan and how, if necessary, the State would transform the highwall to the 30 -foot wide by 40 -foot high <br />reclamation plan bench configuration. Mr. DiLuzio explained the Operator's typical benching sequence. Mr. <br />Cazier explained the process the Division would use to estimate quantities for reconfiguring the highwall to the <br />30 -foot bench for the purpose of estimating a financial warranty. <br />Mr. DiLuzio committed to providing the Division with unit costs for blasting and mucking the benches for use <br />in the Division's cost estimate. <br />Inspection: <br />All parties toured the existing highwall from the pit floor and an upper bench. Mr. Klco pointed out a small <br />seep in the northern end of the working face. The seem appears to correlate with a fault located in this area. <br />The target material is a pinkish -grey granitic gneiss with areas of darker grey hornblende gneiss. Quartz <br />stringers, dykes, and pegmatites cut the formation in multiple locations. The rock mass has several sets of <br />joints, foliations, and fractures, largely striking N30W. Additionally, several faults and sheer zones run through <br />the rockmass. In areas where the rockmass is more massive, the face is held at near - vertical with minimal <br />stability concerns. In areas where the rockmass is more fractured, blocks of up to 3 ft diameter (although <br />generally smaller) were noted on the bench and pit floor. <br />Directly east of the target material are east - dipping sedimentary beds (sandstone red -beds, siltstones, and <br />limestones). This sedimentary package has shown past instability, particularly along the dipslope direction, and <br />along perpendicular cuts that expose differentially weathered materials. One of these failures was pointed out <br />north of the current haul road. The contact between the Precambrian gneisses and the sedimentary beds is of <br />particular concern, since this contact is known to be a weak zone prone to failure. <br />Summary & Recommendations: <br />The Division will estimate quantities to blast and muck the highwall to reconfigure the benches from the 20- <br />foot wide by 40 -foot high operating method to the 30 -foot wide by 40 -foot high reclamation plan bench <br />configuration. <br />The current highwall exposure shows complex and varied geologic structure with multiple foliations, joint sets, <br />intrusions, and fracture zones. All parties agreed that the best approach to evaluate long -term stability of the <br />final highwall is to evaluate the geologic conditions and stability as the mining phases progress. Final highwall <br />geometry may need to be adjusted depending on phase - specific conditions. As each phase approaches the final <br />configuration for the highwall, the local and global stability should be closely analyzed by a qualified person to <br />Page 2 of 8 <br />