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(Page 2) MINE ZD / OR PROSPECTING ID ~ H-80-244 INSPECTION DATE 8-23-94 INSPECTOR S INITIALS ACS OBSERVATIONS An inspection was conducted of the Phase 1 leach pad construction, and of the Ironclad tailing pile and processing facilities. Access roads and storm water controls were also inspected. The main topsoil stockpile (south of the Phase 1 pad), the processing plant construction, and primary crusher installation were also briefly visited. The contractor (Ames) has cut the upper two leak detection trenches on the south side of Arequa Gulch. Work on the third Phase 1 leak detection trench has not yet begun; the third trench will have to be installed prior to placing toe berm fill on the south side of the gulch above approximately 9300 feet. The leak detection trenches were measured in several locations and in all cases were found to exceed the minimum approved dimensions. The trenches have been lined with VLDPE on the bottom and downhill aides. The lined trenches have been filled with leak detection gravel which is wrapped with geotextile. QA samples for gradation testing of the leak detection gravel have been collected at a frequency of one per day during installation. The results of QA gradation testing will be included in the weekly reports. Since the geotextile wrap does not incorporate a stitched closure, a minimum of 1 foot over-lap of the wrapping has been specified. The minimum over-lap has been maintained at all locations inspected, and laborers at the site were observed manipulating the over- lapping geotextile by hand to assure that it le properly positioned. A perforated pipe has been placed within the leak detection gravel at the base of the trench. A 3 inch pipe was specified; both 3 and 4 inch pipes have been used. A location where one of the leak detection channels crosses a secondary underdrain was inspected. The installation was in accordance with the approved detail drawing with VLDPE lining the bottom and both aides of the trench. The .contractor was covering the leak detection trenches with soil liner fill.'.A number of oversize particles (greater than 2 inches maximum dimension) were observed in the soil liner dumped at the leak detection trenches. Dave Kidd instructed the Ames foreman to have the laborers hand-pick oversize from the soil liner fill. The oversize beinq.~removed was cast farther down the slope from the area being filled. The importance of oversize removal will be an emphasis of future Division inspections, and the importance of this aspect of the soil liner installation needs to be emphasized to Ames work crews. The level of intensity and focus being afforded to oversize removal that was observed during this inspection will not be sufficient to assure an adequate soil liner installation. Also, the oversize rocks that are picked out of the soil liner fill need to be loaded out of the pad area and disposed of in select structural fill stockpiles or other appropriate locations. Sediment controls at the pipe outlet carrying Arequa Gulch flows through the lowest Carlton tailing dam were inspected. These sediment controls were installed when cloudy water was observed being pumped from the Phase 1 underdrain Bump at the time of the Division's 8/12/94 inspection. The sediment controls put into place are a aeries of keyed in hay-bale installations. It was observed that these installations are effectively filtering the Arequa Gulch flows. It was further observed that the water exiting the pipe (through the tailing dam) is clear. Apparently it was primary underdrain construction work that was contributing sediment to.flowe from the 24 inch perforated underdrain pipe. Now that primary underdrain installation (for the Phase 1 leach pad) is complete, the flows have cleared up. These sediment controls need to be maintained however, to remove any sediment that is being carried by the Arequa Gulch flows, particularly if the water becomes cloudy again in the future such as during secondary underdrain installation on the north aide of the gulch. The contractor is excavating Carlton tails from the lowest pond and blending them (up to 20 percent) into rock-fill from the north aide of Arequa Gulch. The blended material is being used in construction of the Phase 1 toe berm. This procedure is in accordance with the approved permit terms. Toe berm construction operations were observed. Haul trucks are dumping the rock-fill, which ie then spread into horizontal lifts by a dozer. Compaction of the rock-fill is by a method technique involving routing of equipment and a final pass by a vibratory smooth-drum compactor.' The engineer (Golder) needs to assure, through observation, that the specified number of compaction passes are being completed. These observations should be documented in the daily records. Even though the toe berm is being constructed of rock-fill, some useful proctor and nuclear density information has been collected. This testing should continue eo that compaction QA ie as complete ae ie possible.