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Rifle Gravel Pit#1 April 2022 <br /> Table 2. Estimated Timetable for Phases 1-4 Activities. <br /> Phase/Stage Estimated Estimated Type of Overburden <br /> Duration Depth <br /> Phase 1 Approx. 0.5 Clay and silt; about 6" to 1-foot of topsoil, medium <br /> Site Development 1-2 months feet to 1 foot stiff, slightly moist, brown <br /> & Grading <br /> Phase 2 2-6 months N/A No additional overburden will be removed during <br /> MiningPreparation this phase. <br /> Phase 3 3 - 5 years 17—21 feet Varies <br /> Mining Extraction <br /> 21 feet See Boring 4 Remove estimated 6" of clay and <br /> 30% 1 — 1.5 years (gravel layer silt; gravel layer estimated at 1 foot to 22 feet <br /> thickness) below surface. <br /> 21 feet See Boring 3. Remove estimated 5.5 feet to 6 feet <br /> 60% 1 — 1.5 years (gravel layer of clay and silt overburden; gravel layer estimated <br /> thickness) at 7 feet to 27 feet below surface. <br /> 21 feet See Boring 3. Remove estimated 5.5 feet to 6 feet <br /> 100% 1 — 1.5 years (gravel layer of clay and silt overburden, gravel layer estimated <br /> thickness) at 7 feet to 27 feet below surface. <br /> Phase 4 <br /> (Final 6 months NA NA <br /> Reclamation) <br /> The depths and thicknesses are estimated and based upon the nearest exploratory boring logs included in Attachment C. <br /> 33 <br />