Maintenance, Repair, and Construction of Mains and Services
Core concepts
Know the sequence of main installation: trenching, bedding, pipe laying, joint assembly, thrust restraint, testing, disinfection, flushing, and backfill/compaction. Understand trench safety (sloping, shoring, spoil placement) and proper bedding to support pipe. Recognize pressure testing (hydrostatic) and disinfection (chlorine) procedures before placing a new main in service, including bacteriological clearance.
Repair and maintenance
Learn shutdown procedures: notify customers, isolate with valves, drain, repair (clamp, sleeve, coupling), flush, and restore service. Know service line repair and meter maintenance. Understand preventive maintenance (valve exercising, hydrant flushing, leak detection) and asset management. Recognize water loss control and leak detection methods.
Traps to watch
- Skipping disinfection/bacteriological testing before energizing a new main.
- Forgetting to flush after repairs (sediment, air, contamination).
- Ignoring thrust restraint after a repair at a bend.
- Overlooking confined-space and trench hazards during repair work.
Rule of thumb / worked example
After a main repair, flush until the water is clear and disinfectant residual is restored and stable, then sample if required. Never return a repaired main to service without verifying pressure and bacteriological safety. Document the repair and update records.