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1 1 1 1 ll knob could be borrowed instead of borrowing the same amount of material from the upper impoundment. The Imob made an ideal borrow for the random fill (zone 4) in the main embattlattent. The lower areas of the lower impoundment excavation consisted mainly of alluvial sands and gravels. The north side of the alluvial deposit was composed of clean gravelly sands. The south side of the alluvial deposits had a higher silt content. Material from the alluvial deposit was borrowed selectively and used for Type 1 and 2 fills on the main embanlQnent and drain blanket fills and Type 4 material in the sputter embattlattent fill. 2S Collection Pond Foundation The collection pond foundation was located in the alluvial plain of the valley. Clean sands and gravels were encountered at the fmal depth of the excavation. 3.0 EARTHEN STRUCTURES In total, there are folic ma}or earthen structwes in the tailings disposal area, consisting of the main embankment, the sputter embattlQttent, the collection pond, and the south diversion channel. All earthen structures were constructed using materials which were borrowed from the tailings impoundment facilities excavations. The materials from the impoundment excavations were borrowed selectively based on the gradation and the size of the deposit. The on site materials were classified into four separate categories, referred to as Type 1, 2, 3, and 4. In general, the materials would be descn'bed as follows: Type 1: sandy gravels Type 2: fine gravelly Sand Type 3: sandy silts ' Type 4: random fill For detailed classifications refer to the tailings disposal area specifications. 3.1 Main Embanluaent ' The main embankment was constructed utilizing four Types of material as depicted in SRK as-built Drawing No.14711-104. Fill placement on the main embanlanent commenced in Badly August 1990 1 8