CDM Regulations 2015 for Groundworks: Principal Designer, Notifiable Projects and Construction Phase Plans

Summary

CDM 2015 replaced the 2007 Regulations and significantly changed how health and safety is managed on construction projects. For groundworks specifically, CDM introduces requirements at three stages: pre-construction (identifying hazards and producing pre-construction information), during construction (Construction Phase Plan, site health and safety management), and post-construction (health and safety file).

Groundworks carry some of the highest CDM risk areas in construction: underground utilities, unstable excavations, buried contamination, proximity to existing structures, and heavy plant operations. A poorly prepared Construction Phase Plan that doesn't adequately address these risks is one of the most common compliance failures found by HSE when investigating groundworks accidents.

CDM 2015 applies to all construction work — not just large projects. A domestic extension (single client, domestic premises) has a simplified regime: some CDM client duties are transferred to the contractor. But the safety management duties — preparing a Construction Phase Plan, identifying hazards, providing a safe working environment — remain regardless.

Key Facts

• CDM 2015 — Construction (Design and Management) Regulations 2015 (SI 2015/51); replaced CDM 2007
• Applies to — all construction work, including groundworks, foundations, drainage, and demolition
• Client duty holders — Client, Principal Designer (PD), Principal Contractor (PC), Designers, Contractors, and Workers
• Notifiable project threshold — project lasting more than 30 working days with more than 20 workers simultaneously on site, OR over 500 person-days of construction work
• Notification — Client must notify HSE using F10 form (online) before construction phase begins
• Principal Designer — must be appointed by the Client on projects with more than one contractor; manages pre-construction H&S information
• Principal Contractor — must be appointed when more than one contractor; manages Construction Phase Plan
• Construction Phase Plan — must exist before groundworks commence; proportionate to project size and hazard
• Pre-construction information — hazard information gathered before design; includes utility surveys, site investigation, contamination assessments
• Health and Safety File — final project document; passed to building owner; must include as-built information on foundations, services, buried structures
• Domestic clients — on domestic projects with multiple contractors, principal contractor takes on client duties; single contractor projects — contractor takes on client duties
• HSE project notification — online at hse.gov.uk/f10/

Quick Reference Table: CDM 2015 Duty Holders and Groundworks Responsibilities

Detailed Guidance

Pre-Construction Information for Groundworks

The Principal Designer is responsible for gathering pre-construction information. For groundworks this must include:

Utilities:

• Ground survey to identify buried services — gas, electricity, water, telecoms, drainage
• Use LSBUD (Lines and Cables Searches) and utility operator records; do not rely on drawings alone
• Mark up on site plan; confirm with CAT (Cable Avoidance Tool) and genny scan before excavating
• Minimum 500mm separation from any service line during excavation

Ground conditions:

• Ground investigation report (at minimum, trial pits with soil description and bearing capacity assessment)
• Historical maps to identify any made ground, previous buildings, wells, or contamination sources
• Groundwater level data — particularly relevant for deep excavations

Contamination:

• Environmental Desk Study and Phase 1 assessment for brownfield sites
• Phase 2 site investigation if any contamination indicators found
• Contamination affects: excavation disposal classification (waste classification), worker PPE requirements, concrete specification

Adjacent structures:

• Survey of all structures adjacent to excavations; note proximity, depth of foundations, condition
• For deep excavations within 6m of buildings, a pre-construction survey and monitoring of adjacent structures may be required
• Party wall agreements may be required (Party Wall etc. Act 1996)

Existing drainage and services in the ground:

• As-built drawings from utility operators (not always available)
• Drain CCTV survey if existing drainage routes may be affected

All pre-construction information must be provided to the Principal Contractor before the Construction Phase Plan is produced.

The Construction Phase Plan for Groundworks

The Construction Phase Plan (CPP) is not a generic document — it must address the specific hazards and methods for the project. For groundworks, a compliant CPP includes:

1. Project description and key parties

• Site address, client, PD, PC, key sub-contractors
• Programme overview; groundworks start and completion dates

2. Management arrangements

• Site rules (PPE, induction, permit systems)
• Communication arrangements; emergency contacts
• Welfare facilities

3. Groundworks-specific hazards and controls

4. Emergency procedures

• Collapse of excavation
• Utility strike (gas, electricity, water)
• Contamination exposure

5. Construction sequence

• Order of works; how each phase maintains safety

Proportionality: A domestic extension groundworks CPP can be a straightforward two to four page document addressing the specific hazards for that site. A city centre commercial development groundworks CPP for a basement excavation may run to 50+ pages. The content should be proportionate to the complexity and hazard level.

Notifiable Projects: When to Notify HSE

HSE must be notified on the F10 form when the construction phase is likely to exceed either threshold:

• More than 30 working days with more than 20 workers simultaneously on site at any point, OR
• More than 500 person-days of construction work

For groundworks: most domestic projects are not notifiable. A larger housing development, commercial project, or any project with significant programme duration is likely to be notifiable.

Online notification: Notify at hse.gov.uk/f10. The notification must be submitted by the Client before the construction phase begins. The F10 summary should be displayed on the site notice board.

Changes during construction: If the project scope changes and it becomes notifiable when it wasn't previously, the Client must notify HSE at that point.

Utility Strikes: The Most Common Groundworks CDM Failure

Utility strikes (hitting buried gas, electricity, water, or telecoms services) during groundworks are one of the most frequent serious incidents on construction sites. CDM 2015 requires the hazard to be identified and managed. The HSE's guidance "Avoiding danger from underground services" (HSG47) sets out the required approach:

1. Plan — obtain all available utility records; interpret on a site plan
2. Locate — use a CAT (cable avoidance tool) and signal generator (genny) to confirm routes on site; 'genny' injects a signal onto a pipe or cable which the CAT detects
3. Avoid — design excavations to avoid utilities where possible; plan excavation routes
4. Safe excavation — within 500mm of a utility service line, hand-dig only; no mechanical excavation
5. Response — if a service is struck: gas leak → evacuate and call National Gas Emergency (0800 111 999); electricity strike → do not touch; move everyone clear; call 999 and the electricity network operator

A permit to dig (sometimes called a ground disturbance permit) is good practice and is required on many managed sites. It confirms that utility checks have been completed and that safe excavation procedures are in place.

Health and Safety File for Groundworks

At project completion, the Principal Designer prepares the Health and Safety File. For groundworks it must include:

• As-built foundation details (type, depth, dimensions, any variations from design)
• Survey records of buried services (as-laid positions)
• Ground investigation report and contamination assessment
• Any monitoring data (settlement, groundwater)
• Details of any unusual ground features encountered and how they were handled
• Drainage as-built drawings

The Health and Safety File is handed to the Client on project completion and must be retained for the life of the building. It provides essential information for any future works — renovation, extension, underpinning — that may affect the foundations or buried services.

Frequently Asked Questions

Does CDM apply to a self-build extension with one contractor?

Yes, CDM applies to all construction work. On a domestic project with a single contractor, the domestic client's duties are transferred to the contractor (Regulation 7). The contractor must prepare the Construction Phase Plan before starting and is responsible for managing H&S on site. The Project Designer duties also transfer in this scenario unless a separate designer is appointed.

Who appoints the Principal Designer on a groundworks project?

The Client appoints the Principal Designer. For most projects where an architect or structural engineer is designing the building, they will typically fulfil the Principal Designer role (with explicit appointment and acceptance of the duty). On groundworks-only contracts (e.g. a groundworks package on a larger development), the Principal Designer is typically appointed at the overall project level, not separately for the groundworks phase.

Is a method statement the same as a Construction Phase Plan?

No. A method statement describes how a specific operation will be carried out safely (e.g. how a trench will be excavated and supported). The Construction Phase Plan is the overarching health and safety management plan for the entire construction phase. Method statements are an important part of demonstrating how risks identified in the CPP will be controlled, but they are not the CPP itself.

What happens if groundworks start without a Construction Phase Plan?

Starting work without a CPP is a breach of CDM 2015 Regulation 12. HSE can issue a Prohibition Notice stopping work, or an Improvement Notice requiring a CPP to be produced. For notifiable projects where HSE has not been notified, the same enforcement applies. The Client, Principal Contractor, and individual contractors can all be prosecuted for CDM breaches.

Regulations & Standards

• Construction (Design and Management) Regulations 2015 (SI 2015/51) — primary CDM legislation

• HSE L153 — Managing health and safety in construction — CDM 2015 ACoP and guidance

• HSE HSG47 — Avoiding danger from underground services; utility strike prevention

• Work at Height Regulations 2005 (SI 2005/735) — overlaps with CDM for elevated work in groundworks

• Control of Substances Hazardous to Health Regulations 2002 (COSHH) — contaminated ground handling

• Waste regulations — contaminated spoil is controlled/hazardous waste requiring proper disposal

• CDM 2015 Regulations — legislation.gov.uk — full text of Regulations

• HSE CDM 2015 Guidance L153 — ACoP and supporting guidance

• HSE HSG47 — Underground Services — utility strike avoidance

• HSE F10 Notification — online project notification form

• excavation safety trench support — trench safety and support requirements

• strip foundation design — Building Regulations foundation compliance

• raft foundation guide — alternative foundation type requiring engineer's design

• building regs part h drainage — drainage design and groundworks coordination