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• Construction:
<br />The Tailings Impoundment will be built up in a series of five benches on the down-slope face from the coarser
<br />fraction of the waste stream by hydraulic placement and hydraulic classification. A maximum of 40 square feet of
<br />new impoundment face will be formed daily. A maximum slope of 1.5h: Iv will be maintained at the face. The
<br />finer portions are deposited behind the dam and are covered in water. Sufficient clay (approximately 30% of the
<br />waste stream by weight) is deposited to seal the joints and fractures in the bedrock.
<br />•
<br />The capacity and rate of fill for the Tailings Impoundment has been summarized:
<br />T?hlo 1
<br />Tailings Impoundment
<br />Capacity
<br /> Totals Operating Duration a@
<br />80 ton/day (months) Total
<br />Bench Zone Cu. Yds. Tonnage* Cu. Yds. Tonnage Months
<br />Dam Top of Dam 6,078 9,117 6,078 9,117 3.8 3.8
<br />Bench 1 Step 1 10,081 15,122 6.3
<br /> Step 2 12,893 19,339 8.1
<br /> Step 3 18,713 28,069 11.7
<br /> Step 4 17,444 26,167 59,131 88,697 10.9 37.0
<br />Bench 2 Step 5 16,674 25,011 10.4
<br /> Step 6 18,967 28,450 11.9
<br /> Step 7 20,965 31,447 13.1
<br /> Step 8 23,074 34,611 79,680 119,519 14.4 49.8
<br />Bench 3 Step 9 21,861 32,792 13.7
<br /> Step 10 23,370 35,056 14.6
<br /> Step 11 25,263 37,894 15.8
<br /> Step 12 27,296 40,944 97,791 146,686 17.1 61.1
<br />Bench 4 Step 13 26,167 39,250 16.4
<br /> Step 14 28,824 43,236 18.0
<br /> Step 15
<br />Step 16 30,726
<br />33,185 46,089
<br />49,778
<br />118,902
<br />178,353 19.2
<br />20.7
<br />74.3
<br />Bench 5 Step 17 31,156 46,733 19.5
<br /> Step 18
<br />Step 19 32,830
<br />33,133 49,244
<br />49,700
<br />97,119
<br />145,678 20.5
<br />20.7
<br />60.7
<br />
<br /> Totals 458,700 688,050 286.7
<br /> (months)
<br />* Tonnage figured at 1.5 ton/cu. yd. 23.9
<br />(years)
<br />A network of 4" plastic corrugated perforated drain line, covered with a geo-textile filter "sock", shall be placed
<br />within the impoundment spaced no more than 20' on center. This network shall be connected to the wet sump of the
<br />leachate collection and recycle system. These drains facilitate a more rapid de-watering of the tailings to promote
<br />quicker stabilization of the impoundment. The drains shall be placed on the interface of the impoundment with pre-
<br />existing grade. The drains shall be extended up-gradient as the impoundment expands.
<br />As a secondary, backup system, there shall be placed a similar network at each 20' level of the impoundment
<br />• elevation (corresponding to '/: bench height). This network shall be placed venting to daylight at the impoundment
<br />15
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