REP51942 - Laserfiche WebLink

Home Browse Search

The installation of the five piezometers was completed on September 29. A schematic of the piezometer specifications is enclosed. No water was encountered during drilling and installing of the piezometers. Each location was again found to be dry on September 30. The installation of the five stand-pipe piezometers satisfies the Division's request for verification of the lack of a phreatic surface which could effect the stability of the embankment structure. Tailings Consolidation As outlined in your August 23, 1993 approval letter for placement of the first 10 ft of fill material, settlement markers are in place and are being surveyed daily. mwelve markers are located along the upstream crest of the first 10' of embankment fill, and four markers are located along the upstream crest of the first 20' of embankment fill (see attached location map). The Division requested two markers to be located along the 20' crest; since the earthwork contractor's activities are more difficult to accomplish with the settlement markers in the work area, BMRI increased the number of markers on the 20' crest to four. One marker, #13, along the 20' crest was destroyed during construction. Construction of the first ten' lift was initiated on September 7 and completed on September 11. Each marker, except #13, has been surveyed daily since September 7. The accepted instrument and human error for elevation determinations is +~- 0.1'. The maximum settlement for a single marker was less than 0.5'. The remaining markers settled between 0.2' and 0.4'. The surveys indicate, as expected, settlement during initial loading of the tails with fill material. Since completion of the 10' lift, settlement has not occurred. Note: On September 24, a substitute surveyor operated the instrument and an increased elevation was reported for the majority of the markers. The settlement markers do not indicate unexpected settlement and show no differential settlement.