Groundwork Preparation for Large-Scale Construction Projects
Graeme Blakey - 3rd October 2024
Originally published: 3rd October 2024 | Last updated: 4th September 2026
Large-scale groundworks should begin with information, sequencing and risk control — not with an excavator arriving on an unverified site. The most successful projects establish the ground conditions, buried services, drainage strategy, access requirements, temporary works and material movements before bulk excavation begins.
At DGS Limited, we approach groundworks as the enabling phase that makes the rest of the project possible. Earthworks, drainage, service routes, working platforms and formation levels have to be delivered in the right order because mistakes below ground are expensive to correct once foundations, slabs, roads and buildings are above them.
Our professional groundworks and drainage services support construction and infrastructure work across the North East.
What Should Be Confirmed Before Large-Scale Groundworks Start?
- Site information: surveys, ground conditions, levels, boundaries and existing structures.
- Buried and overhead services: utility plans, locating information and safe excavation controls.
- Construction sequencing: access roads, excavation zones, drainage, service routes and foundation areas.
- Excavation safety: support, battering, edge protection, plant stand-off distances and inspection arrangements.
- Water management: groundwater, surface runoff, temporary drainage and the permanent drainage strategy.
- Quality requirements: formation levels, compaction, material specifications, testing and records.
Groundworks Are a Construction-Phase Management Issue
Under the Construction (Design and Management) Regulations 2015, projects involving more than one contractor require a principal contractor appointed by the client. HSE guidance says the principal contractor must plan, manage, monitor and coordinate health and safety during the construction phase and prepare a construction phase plan before work starts.
That matters directly to groundworks because this phase creates some of the site's most significant temporary risks: open excavations, moving plant, unstable ground, temporary traffic routes, buried services, water ingress and interfaces with other trades.
Groundworks must be designed around the whole site programme
A drainage trench, utility crossing or reduced-level dig may look like an isolated task, but it can affect crane routes, scaffold foundations, neighbouring structures, piling platforms, delivery access and later concrete work. Sequencing is part of safe construction, not just programme management.
1. Start With Site Investigation and Pre-Construction Information
Before excavation, the project team should know as much as reasonably possible about the site. HSE excavation guidance says commercial clients should provide relevant information on ground conditions, underground structures or watercourses and the location of existing services.
Depending on the project, this information can include topographical surveys, utility records, trial holes, geotechnical investigations, contamination information, drainage records and structural details of neighbouring assets.
Approved Document C also addresses the condition of the ground on which buildings are constructed, including unsuitable material, contaminants and sub-soil drainage. The groundwork plan should therefore reflect the actual site rather than relying on generic assumptions about soil strength or groundwater.
2. Locate Underground Services Before Excavation
Buried electricity, gas, water, drainage and communications infrastructure can cross a site in unexpected locations. HSE guidance on underground services is explicit: plans and other suitable information should be obtained, locating equipment used and excavation planned so services are identified before they are exposed.
Service drawings are a starting point, not proof of exact position. HSE advises using locating devices and careful digging practices to pinpoint services. On a major site, service coordination should also cover temporary supplies and new infrastructure that will be installed during the project.
Never assume an old plan gives the exact position of a buried service
Historical drawings may be incomplete or inaccurate. The safe system of work should combine records, locating equipment, site observation and controlled excavation.
3. Plan Excavations as Temporary Works
Excavation sides can collapse without warning. HSE notes that no ground can be relied on to stand unsupported in all circumstances and that a cubic metre of soil can weigh more than 1.5 tonnes.
Before a trench or pit is opened, the team should decide whether it needs support, trench boxes, proprietary systems, battering or another engineered solution. Plant, spoil and materials must also be kept far enough from the edge that they do not overload the excavation.
4. Separate Bulk Earthworks From Final Formation Quality
Large projects can involve substantial cut-and-fill operations. Moving material efficiently is important, but final ground performance depends on more than moving soil from high points to low points.
Formation levels, moisture condition, compaction, material suitability and the requirements of the structural or pavement design must all be controlled. Unsuitable or excessively wet material may need treatment, replacement or specialist engineering advice rather than simply being compacted harder.
| Question | Why it matters |
|---|---|
| Is the material suitable for its intended use? | Different fills and formations have different strength, drainage and compaction requirements. |
| Is the layer thickness controlled? | Compaction equipment can only achieve consistent results through suitable layer depths. |
| Are levels and falls correct? | Incorrect formation levels can affect foundations, roads, drainage and finished external levels. |
| Is testing required? | Project specifications may require density, bearing or other verification before work is covered. |
| Is water being controlled? | Saturated formations can lose strength and delay following trades. |
5. Temporary and Permanent Drainage Need to Work Together
Water is one of the biggest influences on groundwork performance. Surface runoff can erode slopes and flood excavations; groundwater can reduce stability; and poorly sequenced permanent drainage can leave finished areas vulnerable before the final system is operational.
For new development in England, Approved Document H provides statutory guidance on foul water drainage and below-ground drainage. The 2025 national SuDS standards also provide current guidance for the design, maintenance and operation of surface-water drainage systems in new developments.
On a large project, temporary water management should be planned alongside the permanent drainage strategy. This can include temporary channels, sumps, pumping arrangements, sediment control and staged commissioning of permanent drainage.
6. Protect Nearby Structures and Boundaries
Excavation can undermine walls, roads, services and neighbouring foundations. HSE specifically warns that even relatively small trenches can undermine shallow boundary-wall foundations and that structural-engineer advice may be needed where excavations could affect nearby structures.
This is why the excavation line should be checked against structural drawings, property boundaries, retaining structures, scaffold locations and any temporary-load assumptions before digging begins.
7. Working Platforms and Haul Roads Need Engineering Attention
Large construction sites rely on plant movements. Excavators, dumpers, telehandlers, cranes and delivery vehicles all impose loads on temporary routes and platforms. HSE includes haul roads and working platforms within the scope of temporary works that need to be planned and managed.
A surface that is adequate for light traffic may not be suitable for heavy plant, especially after prolonged rain. Access routes should be constructed and maintained for the actual vehicles and ground conditions expected during each phase.
8. Coordinate Drainage, Utilities and Foundations Before They Clash
Many costly site problems are coordination problems. A proposed sewer may conflict with a foundation. A duct route may cross a deep drainage run at the wrong level. A new manhole may sit where a future road or slab detail makes access difficult.
We prefer these clashes to be resolved on drawings and setting-out information before excavation. Where public sewer connections or work near public sewers are required, the relevant sewerage company process must also be followed. Northumbrian Water, for example, requires approval for new sewer connections before the contractor completes the work and arranges inspection.
9. Surface Water Should Be Designed for Long-Term Operation
The 2025 national SuDS standards for England emphasise runoff destinations, everyday rainfall, extreme rainfall, water quality, amenity, biodiversity and long-term maintenance. That means drainage design should consider not only where water goes on day one, but how the system is accessed, maintained and allowed to exceed its normal design capacity safely.
On larger developments, this can affect levels, attenuation storage, swales, basins, permeable areas, pipe sizes, flow controls and exceedance routes. Groundworks deliver these features physically, so the drainage design must be clear before bulk levels and finished surfaces are fixed.
10. Quality Assurance Should Follow the Work Underground
Once groundworks are covered, defects can become difficult to inspect. Good records reduce uncertainty later. Depending on the project specification, quality assurance can include survey records, photographs, test results, pipe levels, manhole details, compaction records, material certificates and as-built information.
Useful groundwork QA records
- formation and finished-level surveys;
- drain invert levels and inspection chamber locations;
- utility duct and draw-pit locations;
- compaction or bearing test results where specified;
- photographs before trenches are backfilled;
- records of unexpected services or ground conditions;
- CCTV records where drainage inspection is part of handover;
- as-built drawings for future maintenance.
How We Sequence Large Groundwork Packages
Step 1: Review site information and constraints
We establish access, levels, utilities, drainage, ground conditions and the agreed construction sequence.
Step 2: Prepare safe access and working areas
Temporary roads, platforms and excavation zones are coordinated with the site logistics plan.
Step 3: Deliver earthworks and underground infrastructure
Excavation, drainage, ducting and service routes are sequenced so they do not obstruct later phases.
Step 4: Verify levels and quality before covering work
Checks and records are completed before backfilling or proceeding with the next layer.
Step 5: Handover clear as-built information
Future maintenance is easier when underground infrastructure is accurately recorded.
Groundworks for Construction Projects Across the North East
Large-scale preparation demands coordination, safe excavation and disciplined quality control. We support developers, contractors and property owners with site preparation, earthworks, drainage and enabling works across the region.
View examples in our project gallery or contact DGS Limited to discuss a forthcoming groundwork package.
Planning a Major Groundworks Package?
Share the site drawings, programme, drainage design, utility information and known ground conditions. We can review the enabling works around the actual construction sequence rather than treating excavation as a standalone task.
