2022-02-09_PERMIT FILE - M2021046 (4)

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aJ�* foster wheeler Zephyr Gold USA Ltd. PAGE 14 OF 15 Dawson Gold Project SEC. NO.: Dawson Filtered Tailings Storage Facility SPECIFICATION 02200.0 Pre-feasibility Study TECHNICAL SPECIFICATIONS FOR DATE: (ORIGINAL) Fremont County, Colorado EARTHWORKS 20-October-16 PROJECT NO.: 74201633 REVISION: A DATE: 20-Oct-16 CONTRACTOR shall place Underdrain Material according to a method specification subject to the approval of ENGINEER and MANAGER. The preliminary method specification shall be as follows: • Place Underdrain Material in continuous lifts no more than 12 inches in compacted thickness. • The material as placed and compacted shall be free from segregation and free of unsuitable materials. Moisture condition the Underdrain Material prior to compaction, as appropriate, maintaining the moisture content required to achieve satisfactory compaction. Use moisture addition procedures during compaction as approved by the MANAGER or ENGINEER. • Compact Underdrain Material with a minimum of two (2) passes of an approved smooth drum vibratory roller with a static drum weight between 8 and 12 tons to achieve a target relative density between 70 and 80%. The number of passes may be modified based on the results of a test fill completed at the start of the embankment construction and/or as approved by the MANAGER or ENGINEER. Excessive compaction of the Underdrain Material that could result in particle breakdown is prohibited. CONTRACTOR shall minimize the amount of traffic over the Underdrain Material to prevent contamination. Remove and replace Underdrain Material containing unsuitable material. 4.5.7 EROSION PROTECTION LAYER The following placement procedures apply to Erosion Protection Layer as classified by the criteria in Article 3.6: The Erosion Protection Layer shall be placed by dozers in a single lift working in an upslope direction. The filtered tailings surface abutting the erosion protection layer shall be prepared by wetting and compacting immediately prior to placement of the erosion protection material. Placement of the Erosion Protection Layer should be concurrent with tailings placement and should be maintained to the crest of the downstream slope of the FTSF to avoid slopes of exposed tailings. 4.5.8 RIPRAP The following placement procedures apply to Riprap as classified by the criteria in Article 3.7: Placement of Riprap shall begin at the toe of the slope and proceed up the slope. The stones may be placed by dumping and may be spread with an excavator or other suitable equipment as long as the underlying material is not displaced. Stones shall be placed so as to provide a minimum of voids. Smaller S:\ZEPHYR MINERALS\DRMS MINE APPLICATION\02200-EARTHWORKS.DOCX