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. . x ~. (Page 2) NINE ID ~ OR PROSPECTING ID f M-60-246 INSPECTION DATE 11-4-94 ~ INSPECTOR'S INITIALS ACS OBSERVATIONS A monitoring inspection of the Phase 1 heap leach pad was conducted. The earthworks contractor was compacting and smoothing soil liner in the north central portion of the pad, above the lower anchor trench. The temperature of the soil liner fill was measured in two locations. The temperature of the soil liner was 45°F with the 6" temperature probe penetrating vertically, and 47°F with the temperature probe penetrating at an angle in an attempt to measure the temperature in the upper 2 inchee of fill. At the request of the Division, the contractor bladed up an area of compacted soil liner near the upper anchor trench eo that thickness of the fill could be observed. The Boil liner thickness at this location was found to be in excess of the 12" required minimum. Later in the day, the CQA monitor noticed an area where the soil liner appeared to be thin. This area was ripped with a motor grader, and the area of deficient thickness was defined. Additional soil liner was brought in to achieve the required minimum thickness. The CQA monitor was observed conducting nuclear density testing of the soil liner fill. There were no failing tests in the area compacted this day. The geomembrane contractor was able to deploy several panels of smooth VLDPE during the afternoon. Deployment, seaming, and pressure testing of welds was observed. No problems were noted. The earthworks contractor rune a smooth drum compactor over the soil liner just prior to rolling out the geomembrane in an effort to smooth out any ruts in the soil liner caused by the wheel loader transporting the VLDPE rolls. It ie important that geomembrane only be deployed onto a smooth, even surface. Other earthworks that were observed to be ongoing this date were: 1) Excavation of the north side upland diversion ditch; 2) Excavation of hill no. 1 to grade; 3) Smooth drum compaction on the leak collection fill (this operation is required in the specifications - not to provide compaction, but rather to provide a smooth, un-yielding bearing surface for the upper geomembrane); 4) Final grading of drain cover on the south side of the pad; 5) Grading of the large topsoil stockpile south and east of the process plant - this is in preparation for a stabilization seeding this year. The leak collection riser pipe alignment was inspected. Leak collection fill had been placed in a continuous lift through the alignment, a trench had then been excavated in the fill to expose the alignment. No damage to the geotextile or geomembrane was observed to have occurred during excavation of the alignment trench (the lowest several inchee of the trench had been dug by hand). The excavation of this trench provided the opportunity to observe a cross-section of leak collection fill that had been placed. No over-size material was observed in the cross-section, however, in several reaches of the exposed cross-section the minimum required 3' thickness had not been achieved. The operator was directed to bring in additional leak collection fill to achieve the required minimum thickness. This can be done at the time that the leak collection riser pipes are covered. See PB 1 on the final page of this report. The leach pad liner tie-in to the process plant was inspected. VLDPE installation in this area has been completed; the extrusion weld to the building foundation was inspected and found to be adequate, but the VLDPE lapping up onto the building foundation must be covered with carefully placed and compacted back-fill. The composite liner had been covered with drain cover fill prior to completion, by backfilling, of the anchor trench. Drain cover fill had been pushed into, and in places had buried the anchor trench. When this was discussed with resident CQA engineer Terry Mandzia k, he stated that this situation had been noted by one of the CQA monitors in their daily report. Terry provided a copy of that daily which is attached to the file copy of this inspection report. The drain cover material will have to be carefully removed from the anchor trench, and the trench backfilled with compacted soil liner fill. See PB 2 on the final page of this report.