4.1.3. Project Scope The intention of this Contract is to backfill and/or seal as many lead and zinc mine related subsidences and openings in Cherokee County as the available funding (normally $160,000 per year) permits, during each year the Contract remains in effect. The SMU has inventoried several sites which encompass varying numbers subsidences and/or openings. After being awarded a contract, the Contractor will be provided a list of sites, along with SMU requirements on which are to be abated first. While abatement of these sites is in progress, the SMU will identify additional sites to be added to the list and backfilled depending on available funding. Openings and subsidences unsuitable for backfilling will be capped or plugged with reinforced concrete structures. Much of the area in which hazards are located are within the EPA Cherokee County Superfund Site, and the mine waste (chat and mill tailings) contains high concentrations of lead, cadmium, zinc, and other heavy metals. Where practical, it is the intention of the project to use chat and mine tailings for backfill in the hazardous openings and subsidences to both eliminate the hazardous piles, as well as to help prevent the materials from contaminating the aquifer due to runoff from precipitation. Funding may be renewed in subsequent years, with sites not filled during one year being moved to subsequent year's lists. The Contractor shall continue to abate hazardous sites until advised to cease work by the SMU. This contract covers the work and materials necessary to backfill SMU designated subsidence sites for a oneyear time period as designated on the Contract documents. All work at each opening will be authorized in the form of Work Orders issued by the SMU. Generally, work at most of the sites will include: a) Large well graded shot rock in the bottom of the excavated hole to reduce further settling and prevent the fill from continuing to wash down the hole. Grout may be required to reduce infiltration and improve stability at some subsidences and openings. Certain problems openings may also require polyurethane foam (PUF) backfill closures, as well as reinforced concrete caps. b) Six inches to one-foot layer of AB-3 or crushed stone on top of the shot rock to fill the voids; c) About 2 feet of compacted clay on top of the crushed stone; d) Sufficient clay, spoil, or other suitable material as required to reach the surface depending on the opening depth; and, e) Where appropriate, approximately 1 foot of soil material covering, graded to drain. 4.1.4. Equipment Requirements The Contractor must furnish appropriately sized equipment to perform the tasks required during the clearing, trash removal, excavation, and backfilling operations in a safe and timely manner. Equipment which may be required includes, but is not limited to: a) Tire-mounted backhoe/loader combination b) Large Track-mounted backhoe w/ thumb c) Small and Medium Dozers such as Cat D3 and D6's d) Front-end Loader (wheeled or tracked) e) Air compressor, jackhammer, and accessories f) Concrete saw g) Skid Steer Loader w/ Accessories (Bobcat) h) Small tractor, box blade, disk, and seeding equipment i) Dump trucks j) Cement and Grout pump k) Portable 50' to 100' stacker conveyor, or auger, with hopper l) Hydraulic hammer for backhoes The Contractor can also be expected to furnish compaction equipment for the backfill on some sites. Depending on the site, this may include air or gasoline tampers, and vibratory roller for hand tamping, as well as wheeled equipment and/or towed rollers for machine compaction.
