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

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aJ�* foster wheeler Zephyr Gold USA Ltd. PAGE 11 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 of material differing substantially in texture or gradation from the surrounding material. The suitability of all materials intended for use in the fill shall be subject to approval by MANAGER and ENGINEER. Fill placement shall be temporarily stopped by CONTRACTOR due to weather conditions or if materials and installation do not meet the SPECIFICATIONS at no cost to OWNER. CONTRACTOR shall apply water required for moisture conditioning on the fill or in the borrow areas. CONTRACTOR shall maintain fill materials within the moisture content range required to permit proper compaction to the specified density with the equipment being used. The moisture content of the fill materials, prior to and during compaction, shall be uniform throughout each layer of the material. After each layer of fill has been placed, spread, and moisture-conditioned, the layer shall be compacted by passing compaction equipment over the entire surface of the layer a sufficient number of times to obtain the required density, as specified herein. Placement, spreading, and compaction for embankments shall be done parallel to the embankment axis in that part of the embankment, unless otherwise specified by the MANAGER or ENGINEER. Materials shall be placed and spread over the surface of the underlying compacted lift. Coverage of the compaction equipment shall be carried out so that the compactive effort is uniformly distributed in a systematic manner over the entire lift. Compaction of individual lanes of a lift shall be completed before beginning compaction of adjacent portions of the lift. Individual lanes shall be overlapped by at least 1 ft. 4.5.2 FILTERED TAILINGS Underdrain Tailings shall be placed according to a method specification based on a trial compaction program conducted at the start-up of operations. The compacted density of the tailings shall be verified periodically throughout operations. This specification shall be subject to the approval of ENGINEER and MANAGER. There will be two zones for tailings placement: (i) Shell Placement Area (Zone 1), and (ii) General Placement Area (Zone 2). The placement moisture content for Filtered Tailings material in the shell placement area (Zone 1) shall be plus or minus 2 percentage points from the optimum moisture content (ASTM D698) and distributed uniformly throughout each layer of material prior to and during compaction. The lift thickness and compaction requirements for the two zones are as follows: S:\ZEPHYR MINERALS\DRMS MINE APPLICATION\02200-EARTHWORKS.DOCX