Opinions Please - H&S issue or not? 2

[EireChch]

Hi all,

I wanted to get the opinion of other engineers. In the attached photo (which I came across on the internet, but reminded me of many instances I have seen onsite inspecting foundations etc), is there a health and safety issue?......

 

[oldestguy]

What's in the trench? If it is concrete, this may be a strip footing. From the photo we don't know if the bearing zone has been checked, but that still can be done along side the concrete. If it is clear stone for draining ground water, it is not a filter and may notwork forever. No hard hat, but that depends on the jurisdiction.

 

[BigH]

From a health and safety issue - it appears that the trenching is less than 1.2 m (4 ft) in height - so that it is not an issue. Nevertheless, all should be aware, even at this height of things like cracking in the soil at the surface that could be construed to potential slide into the excavation. The H&S issue is that the gentleman is not wearing a hard hat. He does have on his vest and boots although I cannot tell if they are steel toed and steel shanked; it they are not, then that is another issue.

 

[EireChch]

OG - sorry i should have clarified, i was more wanting to discuss the issue of excavation stability. There is manholes at either end of the trench so i think it is a pipe that is back filled with concrete (or stone of very similar colour to concrete).

BigH - In Ireland and the UK, we had a similar height specification of 1.25m however this has been removed and it is up to the contractor to confirm if support is necessary. For this case in point I would be concerned, if that gentlemen had to kneel down between the manhole and excavation side an if there was a slip I think the outcome would be very bad. I think battering the excavation side just a little more would improve stability substantially. I understand that it is getting close to the neighboring property, however i think there is still enough space.

 

[GeoPaveTraffic]

Based solely on the photo, I do not see a safety issue with the trench. The soil appears to be a fairly stiff clay and the excavation depth is limited to about 4 feet.

Mike Lambert

 

[PEinc]

While I agree that the excavation looks to be safe, I have these comments:
1. If the excavation is or was more than 4' deep, it needs to be shored or properly sloped.
2. In the US, OSHA says that if there is any water in the soil or trench, the soil is considered a Type C soil which requires at least a 1.5H:1V slope. I see water in the excavation. Does you country have similar regulations?

http://www.PeirceEngineering.com

 

[Okiryu]

USACE has the EM-385 Safety Manual which I use for my projects. Chapter 25 talks about safety in excavations. The EM-385 manual is similar to OSHA requirements for excavations. See link below for the EM-385 safety manual:

http://www.publications.usace.army.mil/Portals/76/Publications/EngineerManuals/EM_385-1-1.pdf

 

[EireChch]

PEinc, an extract below form the Irish Health and Safety Act 2005. It doesn't specifically state what soil type but does say poor soil which i presume would be saturated sands or something equivalent. Trench support below 1.25m depth may be required.

How deep must an excavation be before such precautions need to be taken?

The Construction Regulations require contractors to guard against the dangers from a fall or dislodgement of material in an excavation. The Safety, Health and Welfare at Work Act 2005 requires a risk assessment to be performed by contractors before undertaking excavation work. The risk assessment must:

• identify those hazards that are likely to be encountered;

• determine the control measures; and

• determine the safe system of work required to protect employees and persons affected by the activities taking place.

Control measures selected could be in the form of shoring (support for the excavation), battering (sloping the excavation) or other suitable means.

Note: The risk assessment may indicate the need to install trench supports (or other alternative protective measures) even in relatively shallow excavations less than 1.25 m deep, particularly if ground conditions are particularly poor or the nature of the work requires workers to lie or crouch in a trench.

 

[Silty]

Thanks for the topic, I had this question in my mind for a long time!
It may be quite close to 1.2 m, if that gentleman is around 1.9-2.0 m tall!
Besides, on top of all H&S subjects discussed, I would consider two additional things:
1- Heavy rain!- I see some water at the bottom of trench- if that's coming from rain, it may endanger the safety, due to increase of unit weight of the soil and erosion
2- Duration of exposure- I would rather not to left the trench open for long period of time.