REP29179 - Laserfiche WebLink

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~I t t 1 t 1 The geonet material, placed between the two liners as a leak detection medium, were anchored in the common trench with the primary and secondary liners. All seams were lapped and then tied with plastic ties prior to the primary liner being placed over the surface. All liners and leak detection systems were tied into the collection pond to the west and the collection ditch on the downstream side of the main embanlQrtent to the east. The two collection ditches, at the downstream toe of the main embanlanent, were lined by three liner contractors. Gundle Lining Systems, Gagle Company Inc. and Serrott Corporation. The primary (top) liner consisted of a continuous liner of 60 mil I-IDPE, over the leak detection system wnsisting of a continuous geonet system. The secondary (bottom) liner was the continuous 40 mil VLDPE liner beneath the footprint of the main embanlanent. The primary liner, secondary liner and leak detection system shared a common anchor trench downstream from the main embanlanent. The leak detection system was periodically anchored to the secondary liner by extrusion welding. The primary liner (top liner) was continuously installed over the geogrid system and tied in by the extrusion welding method. All of the extrusion welds were vacuum tested for water tightness prior to acceptance. The tailings ditch liner was installed by Gagle Company. The liner consists of a single sheet of 60 mil fIDPE continuously lined from the conaete structure at the mill to the liner at the upper impoundment. The panels were seamed by using the extrusion welders. The tie-in at the concrete structure was made by placing mastic against the surface of the concrete, then placing the 60 mil liner over the mastic, after which a metal plate with holes drilled for the bolts anchored in the concrete to pass through, then nuts tightened to seal the mastic and the liner to the concrete. All of the extrusion welds were vacuum tested for water tightness, prior to acceptance by the SRK inspector. The water return pipeline ditch liner, consisting of a single sheet of 60 mil I-IDPE, was installed by Gagle Company. The panels were seamed by using extrusion welders. The tie-in at the mill site was beneath the juncture of a steel pipe flange and the HDPE pipeline. The tie-in at the south end was at the north west, downstream, side of the sputter berm. The downstream end was tied into the existing lower impoundment liner, and the upstream end was in an anchor trench. The liner was installed continuously over a prepared subgrade and to the lines and grades outlined on the as built 20