1993-11-10_REVISION - M1988112 - Laserfiche WebLink

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MINfi ID: M-77-001 INSPECTION DATE: 10/15/93 (Page 2 b) INSP&CTOR'S INITIALS: LDO September 30, 1993 In response to Jim Dillie's questions about installation of the synthetic liner Mr. Guyer stated that only 15 patches in a 24 acre area were necessary after rocks were located under installed sections. Mr. Guyer described preparation of the compacted soil liner. Truck dumped material is dozed to a rough grade, after the sub grade has been scarified with a sheepa foot roller. A vibrating smooth drum roller compacts the material. It ie then graded with a road grader and rolled again with a smooth drum roller. Rocks at the surface are picked out by Serrot crews and the Bite ie inspected by both himself and BMRI before final acceptance by BMRI. Mr. Guyer signs acceptance of the installed synthetic liner each day only after he has personally inspected it and checked the contractors quality control. BMRI inspects the synthetic liner and signs acceptance of sections that pass. BMRI said liner installation should be complete by October 20, 1993 and the entire Phase II project including Raise I should be completed by November 15th. Of the 59 acres to be done, 34 acres have been completed. The soil materials borrow area was inspected. The north side of the pit was visited. The material appeared to be relatively free of rocks. Material in this portion of the pit was used for compacted soil liner, Any rocks that were found were weakly cemented sandstone and broke down to sandy material easily. Upon wetting and rubbing the borrow material Larry Oehler noted that it contained a fair amount of fines including some clay. Ms. Scott stated that a specific borrow site was not stated in the permit for the liner and drain layer materials. A large stockpile of material from the West Pit stockpiled for Raise I was observed. It was located in the east end of the tailings reservoir area and would have tc be moved to the raise before the liner can be completed. The first 10 ft. of the embankment raise had been installed at the time o:f the inspection. Consolidation plates were in place beneath the raise as required by the Division. Glen Guyer stated that the raise had been constructed in three lifts of 4 ft., 3 ft. ar.~d 3 ft., and that construction had been completed on September 11, 1993. The borrow material used to construct the first 10 ft. of Raise I contains :onsiderably more than 103 fines. SRK drawing 14719-102 submitted with the San Luie Mine Phase II, Raise I Design Report and received by the Division July 14, 1993, indicates that the entirety of Raise I would be constructed of Type 1 material. One of the gradation specifications for Type 1 material is <10~ fines. This specification is included both in the 1993 design report and in the 1989 amendment approved by the Division. The original approved design for Raise I is a zoned raise consisting of Type 1 material faced on the upstream aide with Type 2 material. The zoned embankment raise ie illustrated in SRK drawing no. 14705-104 submitted with the 1989 amendment. This is the configuration that the Division would consider the approved design, because a raise lacking the Type 2 facing would not have filter compatibility with the tailings. As any case, the first 10 ft. of the embankment raise was not constructed in accordance with designs approved by the Division. October 1, 1993 The inspectors spent several hours inspecting and observing installation of the compacted soil liner, the synthetic liner, the drain pipe system and the drainage blanket. Mr. Guyer explained construction and QAQC for each of these items. All four inspectors were very satisfied with compaction and final preparation of the soil liner as well a~e installation of the synthetic (VLDPS) liner. Allen Sorenson and Bill York-Feirn observed permeability testing of the compacted soil liner and were satisfied with the procedure. These permeabilities are running in the range of 10~ to 10~. It appears that the synthetic liner ie being installed to specifications with very good quality control in locating and patching holes and seaming and testing seams.