Avoiding Underground Services – A Case Study

When previously supporting Electrification and high risk Construction, Design and Management (CDM) projects, it became clear that a simple project can lead to unnecessary risk. A recent project upon which I was asked to provide CDM support involved felling a tree and removing its roots. It was evident that the Construction (Design and Management) Regulations 2015 (CDM 2015) would apply and that, if the client appointed more than one contractor, a principal designer and principal contractor would need appointing.

Case Study: felling a tree

You are the CDM Advisor appointed one week before works commence and you receive the following brief:

The client wants to fell a tree outside a cafe, in a busy high street. They have planned to remove the tree over a bank holiday shut down, while other refurbishment works are taking place.

They have instructed a contractor to carry out the works over two days. Road closures and temporary bus stop closures are in place and have been communicated by highways two weeks in advance of the works commencing.

The site demise will be contained with a two metre perimeter and segregated by chapter eight barriers (plastic safety barriers used to manage traffic and pedestrian flow).

You attend a pre-start meeting and ask some pre-construction questions:

• How many contractors will be involved and does the site demise impact on any other construction works? “well we are refurbishing the Kiosk, adjacent to the site and the road closure might impact on our deliveries”
• How do you plan to remove the roots? “Grinding the stump and digging”
• Have you obtained utility mapping (a process of locating, identifying, and mapping underground utilities)? “no”
• Have you obtained a drainage survey to ensure drains are not impacted? “no”
• Have you carried out a site survey using avoidance tools? “no”

RISK identified: Street lighting and inspection chambers were near the tree’s roots. There is a high likelihood that utilities will be struck and a potential risk to life.

Using HSG47 to manage risk

When breaking ground, the biggest risks are often the ones we can’t see.

Damaging buried services such as electricity cables, gas mains, or water pipes can lead to serious injury, major service disruptions, or even fatalities. That’s why HSG47, the Health and Safety Executive’s guidance on avoiding danger from underground services, is essential for anyone involved in excavation or groundwork.

🔍 HSG47 is built around three key steps:

1. Plan the Work – Gather utility drawings, conduct risk assessments, and plan to avoid high-risk areas.
2. Locate and Identify Services – Use cable avoidance tools (CAT), signal generators, and ground-penetrating radar (GPR).
3. Use Safe Digging Practices – Hand dig where needed, use insulated tools, and follow clearly defined site protocols.

💡 Utility maps are not enough — they must be supported by on-site verification and competent personnel.

Comment

At AfterAthena H&S we emphasise that every excavation, no matter the size, deserves a safety-first approach. Following HSG47 is not just best practice — it’s a lifesaving decision.

Under CDM 2015, it is essential that all pre-construction information is adequately prepared and reviewed by a competent CDM Advisor prior to construction work starting.

✅ **Don’t assume. Check what’s below. Lives depend on it.

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