Grease Trap and Pump Station Maintenance — Safe Work Method Statement

Grease traps under commercial kitchens and sewage pump stations (wet wells) on buildings, subdivisions and rural properties both hold decomposing waste that gives off hydrogen sulfide, methane and carbon dioxide, and both use up oxygen. Hydrogen sulfide deadens the sense of smell at higher levels, so the rotten egg smell is not a warning you can rely on. Grease traps and wet wells usually meet the definition of a confined space, and most of the deaths in spaces like these have been workers who climbed in without testing the air, and the people who went in after them.

The safest way to do this work is from outside. Grease traps are pumped out and scraped down by a vacuum truck operator working from the surface, and pump station pumps are designed to be raised on guide rails with a lifting chain and davit or crane, so nobody needs to go into the well. This template is written for that method. Entry into the space should only happen when there is no other way, and it then needs a confined space entry permit, continuous gas monitoring, a standby person and a rescue plan that does not rely on calling emergency services and waiting.

Whether this is construction work depends on the job. Routine pump-outs and cleaning may not be, so a SWMS may not be strictly required, but the confined space duties in the WHS Regulations apply either way, and building owners and principal contractors usually require a SWMS. Repairs, pump replacement and modifications to a pump station are construction work and are High Risk Construction Work as work in or near a confined space with a possibly contaminated or flammable atmosphere, and falls into an open wet well deeper than 2 metres are a real risk.

Workers need training in confined space work and gas detection. Anyone entering a confined space must be trained for entry. Electrical work on pump controls must be done by a licensed electrician. Liquid waste generally has to be transported by a licensed waste transporter and taken to an approved facility, and trade waste agreements may set pump-out frequencies, so check with your state EPA and the local water authority. Hepatitis A and tetanus vaccinations are recommended for workers who regularly handle sewage.

Customise this template with the site and space details (trap size or wet well depth), the isolation points for pumps and inflows, the gas detector model and alarm settings, the vacuum truck and waste disposal facility, the pump lifting arrangement and its working load limit, the traffic and pedestrian controls, the entry permit and rescue arrangements if entry is planned, and the workers' training records.