_REVISION - M1973021 (3) - Laserfiche WebLink

Home Browse Search

Aggregate Industries, Morrison Quarry Amendment No. 7 to Permit M-1973-021 Morrison, CO October 2021 | 28 Aggregate Industries, Inc. stores material stripped from mining activities within the Central Quarry in stockpiles above El. 6,500, and plans to utilize this material in future reclamation slopes within the South Quarry. Stockpiled material will be seeded in early spring of each year unless currently in use. The stockpiles will be seeded with a mixture of smooth brome and perennial rye or an equivalent mix at a rate of 10 pounds (lbs)/acre by broadcast seeding or hydroseeding. This is a temporary seeding designed to halt erosion of the stockpile material into the drainage. South Quarry Exhibit F.3 shows reclamation within the South Quarry that has been completed along the western slope above El. 7,350. South Quarry reclamation completed to date totals 4.9 acres. The upper benches within the South Quarry western slope have been reclaimed utilizing reclamation slope construction that covers the bench with overburden fill material, placement of topsoil, and revegetation of the bench surface. Planned Reclamation Planned and completed mine bench configurations include highwall configurations of 40H:60V, 60H:40V, and 40H:40V. Mitigation plan details are shown in Exhibit F – Reclamation Plan Maps. Benches above El. 7,000 will be reclaimed, with the placement of additional reclamation backfill to provide improved appearance of portions of the quarry that will be visible to the public. This will utilize the same technique as the currently reclaimed areas within the South Quarry and the western side of the Central Quarry. Concurrent reclamation is planned such that revegetation of upper benches will occur prior to excavation at the lower benches. Reclamation will follow excavation downward, with a general staggering of approximately three to five benches between active mining and reclamation activities. Access roads, haul roads, and maintenance roadways that are not necessary for future land use will be reclaimed by rough grading to blend with surrounding topography, placing topsoil, and revegetating. Areas where structures are existing at the end of mine life will be cleared of debris following dismantling and demolition. Debris will be sent to a licensed landfill facility for disposal. Each area will then be graded to surrounding topography and revegetated according to the requirements of the section below titled Revegetation. North Repository Area Additional fill placement at the North Repository Area (10.6 acres) is planned to mitigate negative visual impacts from early mining in the area. An engineered fill slope on the western wall near the southern end of the North Quarry will provide storage capacity for byproduct materials generated within the quarry. The repository area has been used since 1999 and was enlarged in 2005 using a mixture of structural fill and fine-grained soils identified as jade air fines (JAF), with a finished slope of 2H:1V. The foundation of the toe area of the slope consists of previously placed JAF, and the remainder of the slope is founded on bedrock. Based on the production of byproduct material, the slope will continue to be constructed to a maximum height of 200 feet and has dewatering strip drains located at the base of the highwalls.