closed spaces It exists in many activity sectors and many employees are concerned. Most of the accidents, often serious or even fatal, that occur during interventions in these environments are due to an oxygen-deficient atmosphere, the presence of toxic gases or vapors, or even an explosion or fire. Therefore, the first risks to be evaluated when developing a working procedure are: 

• Anoxia or asphyxia: temporary or permanent lack of oxygen, which can lead to death 
• Poisoning : Poisoning is characterized by inhalation or ingestion of a poisonous gas or product that can cause death. 
• explosion and fire : The presence of gas or dust may create fire and explosion risks. 

Moreover in drinking water treatment and sanitation There are also serious risks such as falling and drowning.

Recommendation R.447, adopted at the meeting of the National Technical Committee on Transport, Water, Gas and Electricity on 25 June 2009, addresses the prevention of accidents occurring during work in confined spaces. , “the need to train personnel in preventing damage and health risks, according to similar prevention and response organizational schemes” is emphasized. 

CATEC® education system: The Certificate of Ability to Work in Confined Spaces in the drinking water and sanitation sector consists of, on the one hand, the qualification reference system in which the training will be created and given, and on the other hand, a system that responds to the need to qualify the qualifications acquired during the training. 

This system provides the company manager with: 

• Markers that will enable people to obtain the necessary authorizations to perform interventions in closed areas (especially in the field of drinking water and sanitation); 
• Assisting in the implementation of mandatory personnel training; 
• CATEC® training List of educational institutions authorized to provide . 

To best meet the expectations of operators, it is divided into two types of training, with a common base and, for each category, specificity for employees and managers:

CATEC® interventionist certification verifies the skills, knowledge and know-how of users in limited areas. The main objectives of this training are:

• Mastering procedures before any intervention
• Identify specific risks depending on the characteristics of confined spaces
• Knowing how to use safety equipment such as portable multi-gas detectors (in this case 4 gas detectors), self-rescue masks, fall arrest harnesses associated with ancillary equipment (safety tripods, fall arresters, safety slings, etc.), air purge fans and ensure they are working properly. Knowing how to check if it's not working
• Master confined space evacuation procedures

CATEC® supervisor certification covers all the essential foundations of CATEC® training. Validates the skills, knowledge and know-how required to fulfill the supervisor role:

• Ensure response conditions are consistently present and maintained until team members are back on their feet.
• Mastering warning and rescue procedures.

To ensure the health and safety of workers who have to work in a confined space, the employer must establish a procedure for such work. This procedure will describe, at a minimum, the work organization specifically adapted to these interventions, the instructions to be followed and the safety measures and equipment to be applied. This procedure can be adapted and completed according to the characteristics of the work areas. 

The minimum equipment level required for working in confined spaces is (excluding the most common):

This is the highest level It is a multi gas detector and is the most frequently used model in drinking water treatment, sanitation, public services and indoor interventions. 4-gas detector simultaneously detects explosive gases ( natural gas , LPG, hydrocarbons, alcohols and solvents), hydrogen sulfide (H2S), carbon monoxide (CO) and oxygen (or rather, oxygen deficiency) detects .

Self-saving masks, They are self-contained breathing apparatus for emergency evacuation in unbreathable, oxygen-deficient or extremely toxic environments. They are closed circuit emergency escape devices (ICES). This means that the exhaled air is filtered and supplemented with oxygen through a small cylinder of pure oxygen (compressed oxygen self-recovery mask) or a potassium superoxide KO2 cartridge (chemical oxygen self-recovery mask).
It is especially necessary in cases of oxygen deficiency or where the concentration of contaminants is too high to be filtered efficiently, for example at very high concentrations of hydrogen sulfide. It is the preferred device for emergency evacuations in limited areas.

In extreme situations and emergencies, SCBAs It is also part of the toolkit for confined space workers. Unlike self-rescue masks, they can be used for on-site intervention or relief and rescue operations. 

They consist of three basic and indivisible elements that form a whole: a harness, a complete mask and a compressed air cylinder. 9 liters at 300 bar compressed air cylinder For those equipped with, they have an autonomy of up to 70 minutes (based on consumption of 40 l/min).

Confined spaces are not immune from the risks of falls from heights and fall protection equipment is a necessary addition to the CATEC PPE list. To ensure that water treatment and sanitation interventions are carried out smoothly, workers must be careful when entering wells or manholes.  safety belt a key anchor point for It is often useful to have a tripod.

Other fall protection equipment completes the range for workers; fall arrest systems, automatic return reels, connection and energy absorption systems, lifelines, etc.

In the presence of significant sources of pollution (oxygen-poor air, significant presence of toxic, asphyxiating or explosive gases), the choice of sanitation technique of the closed area, fans/air extractors dilution using . This technique can be achieved in two ways:

• Ventilation : Persons responsible for the intervention must dilute toxic gases and vapors and provide clean and healthy air throughout the intervention;
• Extraction : To evacuate dust, smoke and toxic gases from closed areas. However, when there is a risk of explosion (very high concentrations of dust or flammable gases) ATEX Choosing an extractor is important.

It should be noted that a fresh air ventilation solution can contribute to the transport of contaminants to a clean area if it allows to disinfect a larger area than the stale air extraction solution.

Other personal protective equipment not mentioned above includes clothing adapted to the working conditions, individual lighting and protective helmets with communication devices are essential. In addition to this PPE, marking equipment for work on public roads and protective devices around open manholes are essential for safe work.