Working in the Ground? Installing Drainage or Services? then this post is for you.
Too many times we see the unnaceptable practice of working in unsupported excavations where the risks just aren’t percieved to be high enough to do anything in the way of additional supports or engineered solutions.
Harking back to my original trainer on the first itteration of Temporary Works Co-Ordinator training, his words ring loudly in my mind “We Dont Let Digger Drivers Make Design Decisions” and his point was clear, those tasked work completion are not the ones that have the responsibilities to ensure the safety of such structures (and they are structures) of excavations for sevices or drainage. In defence of “digger drivers” here, their competence and skill in operating the heavy equipment used in such projects is doubtless, however the design of such structures does lie elsewhere.
This is where the role of the Temporary Works Designer and the Temporary Works Co-Ordinator and Supervisor is key.
Recently a depth of 1.2m was mentioned as being a “safe” depth to dig and install services without additional support. Is that the case? short answer? no, but lets look at where that depth came from:
Where people were called to enter an excavation (to install drainage or services) the Construction (Working Places) Regulations 1966 specified that shoring was required beyond 1.2m. This is our source of such a number. Not a lot of people even rember the 1966 regs working in construction today and its true that the depth did exist but like many things the regulations that gave us the number have long since been replaced.
The 1966 Construction (Working Places) Regulations were revoked in 1996 and the Construction Design and Management Regulations 2007 and 2015 cover it differently.
Those of us that give advice on a range of regulations are familiar with CDM, Reg22 deals specifically with excavations yet makes no reference to depth, instead it requires those in control of work to prevent danger to any person from the collapse of an excavation or any dislodging of material.
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All too often we see reports of shallow excavations collapsing and indeed in the image above the case shows a 1mx0.6m trench causing the death of an employee with a “mere” 1500kg of soil.
Dont rely on the 1.2m rule of thumb, it wont protect you.
Get expert advice, risk assess your work and if you have to make any assumptions, assume that ground wont bear its own weight when working in excavations.
Drop us a line at the contact on this page and we can help.