CSP/Specific Spaces/TBT-CSP-004

Manholes and Chambers

Confined Spaces › Specific Spaces › Manholes and Chambers

Presenter		Project
Location		Date

Manholes and chambers are classified as confined spaces when they have restricted access and foreseeable risk of serious injury.
Hazards inside manholes include toxic gases, oxygen depletion, rising water levels, and biological contamination from sewage.
The Confined Spaces Regulations 1997 apply to all manhole and chamber entries where a foreseeable specified risk exists.
Sewer manholes are particularly dangerous due to hydrogen sulphide gas, methane, and biological pathogens in sewage.
Atmospheric testing must be carried out from above using a probe before anyone descends into any manhole or chamber.
A confined space entry permit must be obtained and the rescue plan confirmed before any person enters the manhole.
The entry controller must remain at the manhole opening throughout the entire entry, maintaining communication with the entrant.
Manhole covers are heavy — incorrect lifting causes back injuries and dropping covers causes crush injuries to hands and feet.
Ladder access into manholes must be checked for condition and security before descending — built-in step irons often corrode.
Water levels in sewer manholes can rise rapidly during rainfall, creating a drowning hazard for anyone inside.

Toxic atmosphere	Sewer manholes contain H2S and methane that kill within seconds — atmospheric testing before entry is the only protection.
Drowning risk	Water levels in manholes can rise suddenly during rain, trapping and drowning anyone inside the chamber.
Restricted rescue	The narrow opening and depth of manholes make rescue extremely difficult — prevention and planning are far more effective than response.

Don't

Treat every manhole and chamber as a potential confined space until assessed otherwise.
Test the atmosphere from above with a calibrated gas monitor before descending.
Obtain a confined space entry permit before any person enters the manhole.
Ensure the entry controller remains at the opening for the entire duration.
Check the rescue plan is in place and rescue equipment is ready before entry.
Inspect step irons and ladders for corrosion and security before putting weight on them.
Use correct manual handling technique or a cover lifter for heavy manhole covers.
Monitor weather conditions — rising water levels can flood manholes within minutes.
Ventilate the manhole with forced fresh air before and during the entry.
Wear appropriate PPE including waterproof gloves and steel-toe boots for all entries.

DON'T enter any manhole without atmospheric testing from above with a gas monitor.
DON'T descend into a manhole without a valid confined space entry permit.
DON'T leave the manhole opening unattended while anyone is inside the chamber.
DON'T enter without confirming rescue equipment is ready and the rescue plan is briefed.
DON'T trust corroded step irons — test each one with your weight before fully loading.
DON'T lift heavy manhole covers without using a cover lifter or correct technique.
DON'T enter sewer manholes during or immediately after heavy rainfall.
DON'T rely on natural ventilation — use forced fresh air supply for all entries.
DON'T enter sewer manholes without protection against biological hazards and H2S.
DON'T assume a shallow chamber is safe — toxic gases accumulate at any depth.

See also: Confined Space Awareness | Hydrogen Sulphide (H2S) on WwTW

Generate professional Risk Assessment and Method Statements in minutes. 10 document formats, site-specific content, instant Word download.

Toolbox Talk Record