2023-07-19_REVISION - M2021052 (12)

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Rifle Gravel Pit#1 July 2023 Table 2. Estimated Timetable for Phases 1-4 Activities Phase/Stage Estimated Estimated Estimated Estimated Type of Overburden Duration Depth Earthwork Area Acres Earthwork Volume CY • Total area= 11.18 acres (for removal of overburden and topsoil) Total overburden=54,111 CY Phase 1 0 Berm construction and reclamation(of berm) (August-September 2023, includes topsoiling 30"cut=42,267 CY Site and seeding) =2.87 acres 6"topsoil = 11,844 CY Development 0 Excess overburden area =varies acres &Grading 0 Excess topsoil area=varies acres Berm overburden= 11,528 CY • Perimeter Area outside berm =3.54 acres. Perimeter Area is not expected to require active Berm topsoil=2,305 CY topsoil 1 -2 months A rox. 30 reclamation due to lack of surface disturbance. Incidental seeding and/or weed treatment Clay and silt- aboutum stiff,, slightly 1-foot of August- inches only, no measurable acreage or treatment cost when combined with contemporaneous berm Excess overburden stockpiled for sale post-berm construction after topsoil, medium moist, s All berm September 2023 reclamation. 60% (secondary commodity) =30,423 CY brown reclamation will be Excess topsoil stockpiled and seeded that can be sold after 60% completed (secondary commodity) =9,006CY during Phase 1 533 CY of topsoil retained and seeded for use in Phase 3 greenbelt area reclamation Phase 2 1-2 months Operations Pad = 1.86 acres 2,999 CY Class 6 No additional overburden will be Mining September- N/A Preparation October 2023 removed during this phase. Phase 3 10.03 acres 226,325 CY Mining 3-5 years Extraction and Nov. 2023—Dec. 17—21 feet Varies Greenbelt 2026 to Dec. 2028 Reclamation 1 —1.5 years The estimated area to be mined (processed and stockpiled)at 30% is approximately 3.67 0 The estimated amount of material mined and processed at See Boring 4 Remove estimated 6" 30% November 2023— 21 feet acres. 30% =70,000 CY of clay and silt; gravel layer Mining November 2024 to (gravel layer estimated at 1 foot to 22 feet below May 2025 thickness) surface. • Underwater and greenbelt reclamation will be completed as mining progresses using GPS 0 Estimated topsoil application 275 CY 30% Contemporaneous 6 inch topsoil technology. N/A Reclamation with 30% Mining application 0 Greenbelt area to be reclaimed with Wetland Mix=0.30 acres (275 CY of topsoil) Cumulative area estimated at 60%=5.58 acres Cumulative volume of material mined and processed at 60% 1 —1.5 years 0 See Boring 3. Remove estimated 60% May 2025—May 21 feet 0 Estimated area mined and processed between 30%and 60% = 1.91 acres = 140,000 CY 5.5 feet to 6 feet of clay and silt Mining2026 to November (gravel layer Estimated volume of material mined and processed between overburden; gravel layer estimated thickness) 30%and 60% =70,000 CY 2026 at 7 feet to 27 feet below surface. • Under water and wetland slope reclamation will be completed as mining progresses using 0 Estimated topsoil application 129 CY 60% Contemporaneous 6 inch topsoil GPS technology. Reclamation with 60% Mining application Greenbelt area to be reclaimed with Wetland Mix=0.18 acres, 129 CY of topsoil [cumulative N/A 0.48 acres, 404 CY total Cumulative area estimated at 100%= 10.03 acres Cumulative volume of material mined and processed at 100% 1 —1.5 ears See Boring 3. Remove estimated 100% November 2026— 21 feet 0 Estimated area mined and processed between 60%and 100% =4.45 acres =226,325 CY 5.5 feet to 6 feet of clay and silt Mining May 2027 to May (gravel layer 0 Estimated volume of material mined and processed between overburden; gravel layer estimated 2028 thickness) 60%and 100%=86,325 CY at 7 feet to 27 feet below surface. • Under water and wetland slope reclamation will be completed as mining progresses using 0 Estimated topsoil application 129 CY 100% Contemporaneous 6 inch topsoil GPS technology. Reclamation with 100% Mining application Greenbelt area to be reclaimed with Wetland Mix=0.18 acres, 129 CY of topsoil [cumulative N/A 0.66 acres, 533 CY total • Verify the mining slopes and greenbelt area slopes using GPS (labor included) 0 Operations Pad will remain as Class 6 road base applied in • Reclaim Berm Area(between berm and greenbelt area) =0.70 acres to receive upland seed Phase 2 and maintained for use in Scott's regional Phase 4 6 months—1 year mix (2.87 acres of the total 3.57-acre Berm Area were seeded during Phase 1). operations. Final May 2028- NA Operations Pad to be maintained as storage= 1.86 acres,temporary structures removed NA Reclamation December 2028 (labor and transport included). The depths and thicknesses are estimated and based upon the nearest exploratory boring logs included in Attachment C. 35