1993-11-10_REVISION - M1988112 - Laserfiche WebLink

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MINE ID: M-77-001 INSPECTION DATE: 10/15/93 (Page 2 a) ~i INSPECTOR'S INITIALS: LDO This inspection was made for the purpose of monitoring construction of the Phase II Raise I lift to the tailings embankment and the Phase II addition to the tailings area liner/drainage-water collection system. September 30. 1993 A pre-inspection meeting was held with all four inspectors, Ken Kluksdahl, Operations Manager - BMRI, Alana Scott, Environmental Coordinator - BMRI and Glenn Guyer, Project Supervisor - SRK. The operator representatives and Mr. Guyer responded to general questions about persons and companies responsible for portions of the construction, installation procedures; materials testing and QAQC. Southway Construction is doing project earthwork and Serrot is doing the synthetic liner, Mike Young of BMRI was named ae the Construction Manager, Glenn Guyer of SRK, Quality Assurance Engineer, Dave Hallman of SRK Design Engineer, Ishmael Hernandez Serrot, Temporary General Supervisor. Southway Construction's on site supervisor is Jim Willshaw, Serrot's Quality Control technician varies from day to day. Mr. Guyer stated that he had been performing 1-12 gradation analyses per day on material used for the compacted soil liner and drainage blanket, but that since the material is very consistent he is now running one per day. He ie doing one permeability test per acre on the compacted soil liner and the results range from 10~ to 10'' cg/s with compactions of 97-101} (approved design permeabilities are 10~ can/s). The thickness of the compacted soil liner is running about 15 inches. The material for the soil liner and the drainage blanket comes from an excavation in the location for the South Waste Rock Dump. The liner material comes from finer materials overlying more coarse materials used for the drainage blanket. Moisture contents are run one time per day and are running 3-4}. This moisture content is used for construction according to Mr. Guyer at the direction of the Design Engineer. Frequency of gradations of material for the embankment raise was 2/day as the stockpile was built and 6-7/day as the embankment was constructed. Allen Sorenson in hie inspection observations ie satisfied that sufficient testing ie done to fully characterize all earth construction materials. In response to Allen Sorenson's question regarding drainage layer material frequency of tests Mr. Guyer responded that one gradation is run per day and that the permeab~ilities have been running around 10' cm/s. The permeability upon which the function of the drainage blanket depends is 5 x 10~ cm/s. The failure to use materials within permit specifications could be considered ae a possible violation of the permit under Section 34-32-124 of the Colorado Mined Land Reclamation Act. it was also observed that the spacing of the drain pipes was regularly over 90' ranging up to 60'. The combination of a lower permeability material in the drain layer with the wider than specified pipe placement, could result in high head on the liner and increased seepage from the impoundment. It could also result in saturated zones within the tails and stability problems concerning the upstream dam raises. BMRI has had surveys run of the consolidation plates placed to monitor settling of the first 10 ft. lift of material placed for the Upstream Phase ZI Raise I to the tailings embankment. Me. Scott reported only minor settling hoe occurred. For the last several days no measurable settling has occurred. The maximum settlement was about 4 inches at one station. BMRI and SRK said they were photo-documenting the Phase II construction activities. BMRI reported that 60} of the compacted soil liner and 50} of the synthetic liner had been installed.