2013-05-16_REVISION - M1990057 - Laserfiche WebLink

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• Monitor compaction lifts, compaction equipment in conjunction with contract soils engineer. • Soils engineer to observe, segregate suitable embankment material, and test placement of embankment fill during construction. Clay Material Segregation, Sub Base Construction, and Geosynthetic Clay Liner Installation • Performed by contractor, monitored by Mill Superintendent and /or Owner's Engineer. • Soils engineer to segregate suitable clay for sub base as required while observing placement of embankment fill during construction. • Grade top of sub base on interior slope and bottom of impoundment ( +/- 1 ") on 50' grid. • Monitor sub base compaction equipment in conjunction with contract soils engineer. • Sub base is compacted on -site soils to 95% standard proctor, +/- 2% optimum moisture. • Finished surface shall be firm and unyielding, without abrupt elevation changes, voids, cracks, ice or standing water. • Liner material contractor will inspect the sub base prior to commencing installation. • Liner material contractor will install and test the geosynthetic clay liner in accordance with manufacture's recommendations. • The liner material contractor will inspect a known perched aquifer seep approximately four -ft above the bottom of the TSF floor and employ one of the techniques below, or equivalent, to minimize premature hydration when laying the geosynthetic clay liner over the seep area. o No special procedures: Seep has minimal flow (damp, dry) or the seep flow is controllable with standard pumping techniques (minimizing standing water) and no additional liner installation techniques required. • Visqueen liner below seep: • Seep flow is controllable with standard pumping techniques (minimizing standing water), but flow from the seep may cause hydration of the geosynthetic clay liner below the seep faster than desired. • Visqueen or equivalent liner placed from the seep to the TSF floor, reducing hydration of the GCL material and directing seep flow to the TSF floor for control by standard pumping techniques. • Subdrain along seep: • Seep flow is not controllable with standard pumping techniques (standing water). • Installation of subdrain along seep, directing water from seep to an infiltration area within the TSF structure as shown in Figure C -7, Subdrain Detail and Figure C -8, Subdrain Location. Following installation of the subdrain, compaction to 95 % standard proctor, +/- 2% optimum moisture, and grading of sub base on interior slope +/- 1" on 50' grid, then the geosynthetic clay liner is installed. • If the geosynthetic clay liner is prematurely hydrated during installation, it may remain in place if the following conditions are met. o Geotextiles have not been separated, torn or otherwise damaged. M1990 -057 May 14, 2013