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Confined spaces

With reference to municipal and industrial applications

Far from being a hospital ward where a joyous event occurs, a confined space, if not recognized and addressed correctly can become the site of an incident; rising in severity from a minor injury and source of bureaucratic frustration, to the death of one or more persons. A pump station wet-well, an underground office, a garage or any area where the airflow may become restricted could be a 'confined space'.

Entry into a known confined space is prohibited under law unless a 'competent person' has authorized the entry in writing. Labour relations can be severely jeopardized by contravention of this aspect of the Occupational Health and Safety Act and every employee has a right to report lapses to the authority. Claims can be financially crippling and management will (usually) be held fully accountable. The following may seem draconian at first reading, but think about it. It is common sense really, and leads to good management and efficient maintenance procedures, for the benefit of all.


Definitions

  1. Incident
    A reportable accident, dangerous occurrence (personal injury, fire, flood, etc.), or digression from established safety practice as defined under the Occupational Health and Safety Act.
  2. Confined Space
    A closed, restricted or limited space in which any hazardous substance may be introduced or may accumulate or where an atmospheric oxygen deficiency may occur. For our present consideration such confined spaces would be pump station wet-wells, wastewater drainage pipes, sewage main inspection chambers and industrial grease trap sumps, among others.
  3. Competent Person
    The Act is a little unclear on this point with regard to the meaning of the word 'competent'. The onus is on the employer to ensure that the person responsible on site is competent and experienced in the job at hand. The more previous experience he's had with 'incidents' (where something went wrong), the better.


Procedure

As an example, let's take a typical pump station wet-well that needs to be de-fatted. A minimum three-man team is mandatory: one man, suitably dressed and equipped to enter (see below), and two to remain on the surface - their function being to withdraw the one man should he meet with an accident or be overcome by fumes. Typically a man weighs in excess of 85kg, which is more than one man can lift by himself.

The Competent Person must ensure that before anybody enters a confined space they are correctly attired and equipped and that it is safe to go in. He must…

  • Ensure that barricades and warning signs are erected in public spaces;
  • Check the air quality to verify the need for breathing apparatus;
  • Ensure workmen are properly dressed. No cell phones, matches or spark-generating devices are allowed;
  • Ensure the men know what they have to do;
  • Test the safety harness (not a rope, a proper approved harness) and check that the safety rope is strong enough, long enough and securely belayed outside the confined space;
  • Check that the men understand the signal system to be used – tugs on the rope or calls (‘buddy’ technique);
  • Check that the man going into the confined space has a torch, oxygen meter and the correct tools – a lower explosive level meter (LELM) and a movement alarm meter (MAM) are advisable;
  • Ensure that certified breathing apparatus and an alternative air supply is at hand should it be required;
  • Monitor the incoming effluent (especially with regards to pump stations receiving from industrial areas) with a view to detecting hazardous gases or vapors; and
  • Ensure that nothing (tools/equipment) remains in the confined space following the completion of the work and prior to closing and securing the hatches.


Should an incident result in litigation, the Chief Executive Officer of the organisation concerned will be held accountable. He is responsible for ensuring that the chain of command to the operator is via qualified 'competent persons’ and will be held personally liable under the law for any infringement of the regulations, which must be made known to and available for inspection and study by any employee so dispatched.

Financial implications

The cost of breathing apparatus, protective clothing, recovery harnesses and peripherals necessary to enter a confined space is in excess of R30 000 per person. Add to this the cost of labour as well as the planning and preparation time, and it follows that entering a typical 60 cubic meter (hydraulic) capacity wet-well is a very expensive business. Considering the nature of effluent these days (see Changes in modern effluent), especially the concentrated sewage from new low-cost housing estates – which necessitate the cleaning of pump stations every three to four months – the maintenance of sewage transportation, even for a small town, has become a huge drain on the public purse.

The BIO-SYSTEMS alternative

Today, a large percentage of the above cost can be avoided. By inoculating with BIO-SYSTEMS B220R to control and prevent the build up of fats, oils and greases (FOG), maintenance can be limited to an annual vacuuming of grit from the floor of the well. Free-floating textiles and buoyant solids won't be congealed in a thick crust and can be removed with relative ease. Both are jobs that can (usually) be done fairly easily, without having to enter the confined space of the wet-well.

Taking hard costs for a typical wet-well into account, assuming that the pump station has been well maintained, it will cost in the region of R2 000 for the initial inoculation and thereafter R400-R600 every month to six weeks depending on seasonal flow. Add to this the reduced wear and tear on the pumps, reduced power demand, freedom from odour and the fact that a better quality effluent will be delivered to the Wastewater Treatment Works, and  the choice is obvious.

Click here to go back to Odour prevention.

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