South Dade Landfill - Cell 5 Side Slopes Stormwater Drainage Improvements

South-Dade Landfill – Cell 5 Side Slopes Stormwater Drainage Improvements **Construction work shall be performed during landfill operation hours, Monday - Friday, 7:00 AM to 5:00 PM, unless otherwise authorized by the Owner.** The Owner (Miami-Dade County Department of Solid Waste Management) is soliciting a qualified Contractor to complete stormwater improvements at the South-Dade Landfill, Cell 5. The Work includes, but is not limited to, the tasks described below: *Intermediate Soil Cover Place an 18-inch layer of soil over the existing solid waste forming the three side slopes of Cell 5, covering approximately 10 acres of 3H:1V slopes. Soil will be provided by the Owner and staged near the top of the slopes. Refer to Attachment 1 for slope geometry, as well as the section titled “Comments to Attachment 1.” *Soil Spreading and Compaction Spread and compact the soil to create a stable, uniform surface. Bulldozer placement and compaction are acceptable. Completed surfaces shall exhibit consistent thickness, smooth contours, and stable slope conditions. The Owner will visually inspect the finished surfaces for flatness and will perform spot checks to verify soil thickness. Provide a smooth transition between the slopes of Cell 4 and Cell 5. *Pipe Supply – Downcomer Installation Materials Provide approximately 960 linear feet of 24-inch corrugated HDPE pipe for use in downcomer installations. Pipe shall be manufactured by ADS or an approved equal. *Pipe Supply – Additional Materials Provide an additional ten (10) 20-foot lengths of 24-inch corrugated HDPE pipe to be retained by DSWM as spare material. All pipe shall be manufactured by ADS or an approved equal. *Downcomer Installation Install six (6) downcomer assemblies, each approximately 160 feet in length, consisting of lengths of 24-inch corrugated HDPE pipe with watertight bell-and-spigot joints. Each assembly shall be equipped with a geotextile screen at the upper end (cell 5 deck level), to filter out soils and other debris. Place the pipe directly on the newly installed soil cover and anchor it with soil mounds spaced at 20-foot intervals. Each mound shall extend 3 feet along the pipe, 5 feet across the pipe, and rise 1 foot above the pipe crown. Install the pipe straight and in a manner that maximizes frictional contact with the soil to resist downslope movement. At the discharge end, securely connect to existing stormwater energy dissipators. At the inlet end, penetrate the stormwater control berm and place the end with bottom of pipe flush with the cell 5 deck. *Stormwater Control Berms Construct approximately 3,650 linear feet of stormwater control berms along the top of the side slopes of Cell 5 to intercept stormwater runoff from the top deck and direct flow to the downcomer inlets. Berms shall generally follow the 60-foot elevation contour shown in Attachment 1 and referenced in “Comments to Attachment 1.” Berms shall be a minimum of 2 feet high and 2 feet wide at the crest, and compacted to at least 90 percent of Standard Proctor density. Tie berms smoothly into adjacent grades. *Hydroseeding Hydroseed approximately 10 acres of newly placed soil using Bahia grass and a heavy mulch load for slope stabilization. Use commercial hydroseeding equipment designed for mixing and uniformly applying a slurry of wood-fiber mulch, seed, fertilizer, tackifier, and dye. Wood fiber shall be 100 percent virgin hardwood or softwood with no recycled or reprocessed content. Mix proportions shall comply with technical specifications. Fertilizer shall be Florida friendly. *Erosion Control Blanket Installation Furnish and install biodegradable erosion control blanket over the hydroseeded 3H:1V slopes (approximately 10 acres). Blanket shall consist of a 70/30 straw-to-coconut-fiber blend. Install blankets in accordance with manufacturer recommendations, including proper deployment, overlapping, anchoring, and ensuring continuous contact with the soil surface. The manufacturer shall be as indicated in the technical specifications. *Erosion and Sediment Control (ESC) Install and maintain ESC measures to prevent erosion and sediment migration prior to beginning earthwork. ESC measures include, but are not limited to, silt fence, inlet protection, check dams, and stabilized construction entrances. Maintain ESC measures throughout construction until final stabilization. *Mobilization and Demobilization Provide all labor, equipment, materials, planning, permits, pre-construction submittals, signage, and temporary protections necessary to complete the Work. Mobilization includes health and safety plan, site visits, staging, and preparation for construction. Demobilization includes removal of equipment, cleanup, and site restoration. **Mobilization activities include, but are not limited to: • Photographic Documentation Provide photographic documentation of pre-construction conditions, construction progress, and final post-construction conditions. • Coordination with Landfill Operations Coordinate daily with landfill operations staff regarding work windows, haul routes, active face activities, and safety requirements. • Housekeeping and Site Restoration Maintain clean haul roads and work areas. Remove debris, excess soil, and temporary facilities. Restore all non-seeded disturbed areas to pre-construction conditions. Comments to Attachment 1 (Drawing): • The road represented in Attachment 1, providing access to the top of Cell 5 and located on the north side slope of the cell, is not part of this scope of work. • Downcomers shall be installed from the energy dissipators to approximately the contour line corresponding to 60 ft elevation, at the edge of the new intermediate cover area, resulting in a length of 160 ft each. • Attachment 1 does not show the berm, but the berm is part of the scope as described above. Additional Information • The Contractor shall coordinate with the Owner’s Authorized Representative to phase the work to not impact facility operations, equipment, and circulation of vehicles. • Facility hours of operation are 7 a.m. to -5 p.m. and operations shall remain unaffected throughout the construction project. • All work shall be performed during the facility’s normal hours of operation unless otherwise authorized in writing by the Owner’s Representative. Any work performed outside the facility’s normal hours of operation shall not be eligible for overtime compensation or additional billing to the Owner.