1.5 Years of Heavy Construction in 1.5 Hours - Practical Engineering - Sewage Lift Station Construction Summary
0:00 Introduction: Grady introduces the project: a new sewage lift station in rapidly-developing San Antonio, Texas, highlighting the importance of wastewater infrastructure for population growth.
1:21 Project Background: The purpose of the lift station is explained - to pump sewage uphill when gravity flow isn't possible. The new station will add capacity and redundancy to the existing system.
2:44 Excavation Begins: The video details the initial excavation process, emphasizing safety regulations and the use of sloped sides to prevent collapse.
4:50 Shoring Installation: Due to the depth and narrow site, a slide rail shoring system is installed to support the excavation walls, allowing for safe digging at greater depths.
9:12 Subgrade Compaction: After reaching the final depth, a miniature remote-controlled roller compactor is used to compact the soil at the bottom of the excavation, creating a stable foundation.
11:56 Working Slab Placement: A concrete working slab, or mud slab, is poured at the base to protect the soil during construction and establish the correct elevation for subsequent work.
14:48 Wet Well Installation: The primary component, a precast concrete wet well, is delivered in segments and assembled using a large crane. Gaskets and lubricant are used to ensure watertight joints.
23:38 Wet Well Leak Test: After grout and waterproof coating are applied to the joints, the wet well undergoes a leak test to confirm its integrity before backfilling.
25:00 Backfilling and Shoring Removal: The wet well is backfilled with a combination of Controlled Low Strength Material (flowable fill) and compacted soil, carefully coordinating with the removal of the shoring system.
32:55 Sewer Line Installation: Trenches are excavated and shored for the installation of three sewer lines connecting the wet well to the existing system. Select gravel bedding is used to support the pipes.
35:13 Drilling Wet Well Penetrations: Holes are carefully cored into the wet well to connect the sewer lines at the correct elevations for gravity flow.
41:38 Existing System Connection: The video highlights the connection of the new wet well to the existing lift station using manholes and plug valves, ensuring flexibility and redundancy.
52:22 Large Valve Installation: A large plug valve is installed on a 24" sewer line, requiring a bypass pump to redirect wastewater flow during the installation process.
56:45 Electrical Conduit Installation: Trenches are dug and conduits are installed to provide underground electrical connections for the pumps and control systems.
58:07 Control Shelter and Equipment Slab Construction: Concrete slabs are poured for the electrical shelter and equipment pad, highlighting the importance of rebar, formwork, and concrete testing.
1:00:37 Wet Well Cover Slab Construction: The concrete slab covering the wet well is installed, using void forms to ensure it settles with the wet well and precast concrete retainers to prevent soil collapse around the edges.
1:10:32 Diesel Pump Slab and Electrical Rack Installation: A dedicated concrete slab is poured for the backup diesel pump, and an electrical rack is installed at the wet well for connection to the control systems.
1:11:49 Manhole Completion and Epoxy Lining: The manholes are finished with cast iron covers and concrete surrounds. An epoxy liner is applied to protect the manholes and wet well from the corrosive sewage environment.
1:14:53 Discharge Piping Installation: Above-ground piping is installed, connecting the pumps to a manifold, flow meter, and the force main, emphasizing the use of flanges, gaskets, and valves for a secure and maintainable system.
1:20:59 Pump Installation: The three main pumps are lowered into the wet well, highlighting their features for handling sewage and their simple installation process using guide rails.
1:22:41 Control Systems: The video details the electrical power supply, transformers, disconnect switches, and control panels, emphasizing redundancy and safety features.
1:26:03 Diesel Backup Pump and Emergency Bypass: The installation of a diesel-powered backup pump and emergency bypass are shown, ensuring continuous operation during power outages or equipment failures.
1:28:10 Force Main Connection and Site Cleanup: The new lift station is connected to the force main, backfill is completed, and the site is cleaned in preparation for final testing.
1:33:01 Pump Testing and Project Completion: The pumps are tested with water to confirm proper operation. The video concludes by showcasing the completed lift station and emphasizing the importance of hidden infrastructure in our modern world.