Deaths in confined spaces

Offlate, I started reading persons overcome by the atmosphere while working inside the septic tanks, underground water storage reservoirs / tanks, chemical storage tanks, etc. In some cases, persons while working in trenches, were buried alive by the soil heaps next to the trench. In one case a person was working only about at a meter depth, but he was buried when the soil was disturbed.

Some of the deaths were like this;

1. A Person want to see what is inside a tank from the top, to plan for the work. While looking down, he lost consciousness, fell down and died. Sometimes, to rescue the unconscious persons, others who tried for him also became victims.
2. A person went inside a rice brawn mill discharge storage tank. After some time, he became unconscious and was found dead.
3. A person went inside a water storage tank in the underground for cleaning and was found dead.
4. A person went inside a concrete mixing plant for cleaning. Not knowing this, soon after, the operator operated and the person inside died. Though in this case, it is not the hazardous atmosphere, but it is a confined space and a different type of hazard (Maintenance person's presence inside is not known to the operator).
5. Two persons were working in a trench and were buried alive by the loose soil heap that slid due to some disturbance.

There are many more such cases, mostly involving cleaning jobs inside waste storage tanks of rice brawn mills or septic tanks.

Earlier, while reading such news items, I used to think that my work place is safe and that I need not bother about confined space works. However, as I learn more and more deaths of people like above, whenever I get a work permit for work in a basement or tank, though it is fairly open to atmosphere, I get wild thoughts and sometimes I think whether I am thinking too much in visualizing the hazards. However, I stick to my wild thoughts and accordingly prepare precautions to be taken for the work.

Normally, the oxygen level in the work place will be checked before entry into such places. People say that it is fine if oxygen levels are between 19.5 % and 23.0%.

But in an article, the author advised to verify and find out the reasons for change in oxygen level from the normal levels. Though the general guideline says above 19.5% O2 levels are acceptable, but what are the other pollutant that brought down the O2 level from 21% to 19.5%? For example, if the pollutant is say CO, then we all know that CO is fatal at 0.5% (5,000 ppm) and it is not acceptable. Similarly, it may by H2S which is also a toxic gas.

Sometimes, our instrument may be wrong. In that case we can't depend on the values measured by it, because we do not know the error %. Sometimes, persons check O2 level at the entrance and then give clearance for the work. But, we should check O2 levels at the actual place of work and the measurement time should be reasonable. Instantaneous values may give us wrong picture. Again for checking O2 levels at work place, we should not enter and endanger our lives. Portable hand held instruments with suction pumps and connected hoses (even upto 100 ft) are availalbe at about Rs 30,000/- in the market.

We have to flush the work area continuously till we get O2 levels are as good as open atmposhere and should continue air supply till the work is over and all persons come out. If the work is to be carried for a long time with tea / lunch breaks, then the flushing and air supply should be continued during the breaks and before every entry, the O2 levels should be checked and ascertained that the work atmosphere is safe for work.

Sometimes, there may not be much head room available for free movement of the persons inside. In case of work inside chimneys or furnaces, the lining material may be loose and it may fall on the persons. There may be toxic gases (generated by the process) that are trapped in these lining material and if persons are working on these, they will be exposed to these toxic gases and may be overcome.

When persons work in open trenches, we know that the adjacent heaps of soil can be disturbed by heavy winds or from vibrations due to vehicular movement nearby. It is normally suggested to dispose the soil immediately to an earmarked place. Atleast, the soil should be kept atleast 1.5 m away from the trench and angle of repose should be considered for the soil. Again, as we go deep in the trenches, they should be supported on the sides to avoid collapse due to loads on the adjectent area by proper shoring. If long trenches are made, then for every 30 m, emergency escape ladders should be provided. Care should be taken that these trenches are not flooded by water / sewage lines and workers in it are taken by surprise. Earth moving equipment should be properly supported by outer rigs with proper base supports so that they do not topple due to loose soil and in the process endanger persons nearby.

With the availability of radio sets, workers inside should be in constant touch by the supervisor outside and buddy system should be followed on one-to-one basis i.e for every one person inside, there should be another person outside to monitor the condition and to provide immediate help. People may think it is waste of money, but in the event of some eventuality, the compensation claims and payments will put a big hole in the finances of the executors of the work and then they will regret for not taking protective measures.

However, the story repeats in the next job. BECAUSE, OUR MEMORY IS SHORT AND WE THINK THAT THOSE INCIDENTS ARE OF ONCE IN LIFE TIME AND THEY WILL BE CAREFUL THIS TIME.

Such persons should be put behind bars, with all their propery seized and utilized for helping the families of the victims.