Connecting new drainage into a live sewer involves breaking into a pipe that may contain raw sewage, toxic gases, and biological hazards. Hydrogen sulphide gas can accumulate in sewers at lethal concentrations. Workers making these connections face infection risks, confined space hazards, and the danger of sudden surges of flow. This talk covers the controls needed for safe live sewer connections.
Key Hazards
Hydrogen sulphide gas exposure at toxic or explosive concentrations
Biological infection from contact with raw sewage and wastewater
Sudden flow surge flooding the work area during the connection
Confined space atmosphere in deep manholes and sewer chambers
Control Measures
Obtain a permit to work and confined space entry permit before breaking into a live sewer.
Monitor the atmosphere continuously for H2S, methane, and oxygen levels using calibrated gas detectors.
Arrange temporary over-pumping or flow diversion to reduce sewage flow during the connection.
Wear full biological hazard PPE including waterproof coveralls, gloves, face shield, and boots.
Ensure all operatives have up-to-date hepatitis A and tetanus vaccinations.
Provide hand washing facilities and antibacterial wash at the work location.
Never eat, drink, or smoke near the connection work area to prevent ingestion of pathogens.
Ensure rescue equipment including a tripod and winch is available for manhole entry.
Brief all operatives on the emergency rescue plan and gas alarm action levels before starting.
Emergency / Rescue
If the H2S alarm sounds or anyone feels dizzy or nauseous, evacuate the excavation or manhole immediately. Move upwind to fresh air. Call 999 and do not re-enter the space. Activate the confined space rescue plan if anyone is incapacitated below ground.
Remember
Always obtain a permit to work and confined space entry permit before breaking into a live sewer
Monitor the atmosphere continuously for H2S, methane, and oxygen throughout the operation
Wear full biological hazard PPE and wash hands thoroughly before eating or drinking
Arrange over-pumping or flow diversion to reduce sewage levels during the connection
Ensure rescue equipment is set up and the emergency plan is briefed before any entry
Vaccinations for hepatitis A and tetanus must be current for all workers on sewer connections
Applicable Legislation: Confined Spaces Regulations 1997 · COSHH 2002 · CDM 2015 · Water Industry Act 1991