A council housing scheme can look straightforward on a planning drawing and become a very different proposition once excavation starts. Buried obstructions, weak ground and drainage constraints can change foundation designs, disrupt programmes and put pressure on public budgets. I would rather see those risks challenged before tender than negotiated around an open trench.
For councils commissioning new homes, good groundworks procurement starts with asking for evidence, not accepting reassurance. These first two questions focus on the information and decisions that should underpin a buildable scheme, before price and programme commitments become difficult to change.
1. Do we understand what is beneath the site?
A site being allocated for housing does not mean its ground conditions are suitable for the proposed development. Former industrial land, demolished estates and apparently untouched plots can all present different risks. My starting point would be simple: does the ground investigation support the homes we actually intend to build, or does it merely provide a broad picture of the site?
A desk study helps establish previous land uses, geology and potential hazards, but it cannot settle every design question. The scope of intrusive investigation should reflect the proposed layout, likely foundation loads and risks identified by suitably qualified specialists. Trial pits, boreholes, laboratory testing and groundwater monitoring may each have a role, depending on the site.
Ask whether the evidence supports the design
The council’s project team should be able to explain how the investigation findings translate into foundation, road and drainage designs. An isolated test result is not a site-wide guarantee. Where access restrictions have left gaps beneath existing buildings or hardstanding, those gaps should be recorded and addressed through a planned follow-up investigation.
- Ground strength and variability: Is there enough information to assess bearing capacity, settlement and changes in ground conditions across the proposed building footprints?
- Previous development: Could old foundations, basements, tanks or poorly compacted fill affect excavation and construction?
- Contamination and ground gas: Have potential risks to residents, construction workers and controlled waters been assessed, with any necessary mitigation identified?
- Groundwater: Could water levels affect excavations, foundation construction or the suitability of infiltration drainage?
- Excavated material: Has the team assessed opportunities for suitable reuse and the testing needed to establish lawful disposal routes?
Make uncertainty visible before procurement
I would ask for a ground risk register alongside the investigation reports. It should distinguish confirmed findings from assumptions, identify further work and name the party responsible for resolving each outstanding issue. This gives procurement teams something more useful than a general statement that ground conditions are “the contractor’s responsibility”.
Passing an uncertain risk into a contract does not make it disappear. It can lead to larger pricing allowances, qualifications or later disputes, depending on the contract terms. Clear information and explicit risk allocation give councils a better basis for comparing tenders and judging whether the groundworks budget is realistic.
2. Is there a workable drainage strategy, with a clear route to approval?
Drainage should help shape the housing layout, not be squeezed into the space left over. Pipe gradients, finished floor levels, storage requirements and discharge arrangements can all influence how many homes a site can accommodate and how its public spaces work. I would challenge any programme that treats these matters as details to resolve after the layout has been fixed.
A credible strategy needs to address foul and surface water separately, while considering how the whole development behaves during heavy rainfall. The relevant approval processes differ across the UK, so councils should establish which planning, drainage and sewerage bodies need to be involved and what evidence each requires.
Check the proposed discharge route
A nearby sewer does not automatically provide an available or acceptable connection. The team should establish the proposed connection arrangements, any capacity constraints and the permissions or agreements required. If drainage must cross third-party land, the necessary rights should be investigated early rather than left as a construction-stage problem.
For surface water, infiltration should only be relied upon where site-specific assessment demonstrates that it is suitable. Ground permeability, groundwater levels, contamination and proximity to structures can affect that judgement. Where another discharge route is proposed, its feasibility, allowable flow and storage implications need to be understood.
Ask how the system will work after handover
Sustainable drainage systems, often called SuDS, can manage runoff while improving amenity and biodiversity. However, a swale, basin or permeable surface needs more than a place on a drawing. The design must account for maintenance access, sediment management and who will fund and carry out upkeep.
I would want the project team to show where water goes if an inlet blocks or rainfall exceeds the system’s design capacity. Exceedance routes should be planned to reduce risk to homes and neighbouring land. Alongside that explanation, the council should have a clear schedule of outstanding approvals, adoption arrangements and maintenance responsibilities before committing to the groundworks programme.
3. Have we identified existing services and secured the utility connections?
A utility line on a drawing is not proof of its exact position underground. Equally, a mains supply running past the site does not guarantee enough capacity for the proposed homes. I would treat existing services and new connections as two separate workstreams, with a named person coordinating the relationship between them.
Establish what is already in the ground
Utility records are a starting point, not permission to excavate. They should inform a suitable detection survey and, where necessary, carefully planned verification excavations. The investigation needs to consider redundant services too, because an apparently abandoned pipe or cable should not simply be assumed safe.
The council should ask how service information will reach the people carrying out the work. Survey results are only useful if they inform excavation methods, briefings and controls on site. Where the development sits within an occupied estate, maintaining supplies to existing residents must form part of that planning.
- Location and status: Which services have been identified, and which still require verification?
- Protection and diversion: Do proposed foundations, drainage runs or roads conflict with existing apparatus?
- Access rights: Are easements, wayleaves or utility protection corridors restricting the layout?
- Continuity: How will essential supplies remain available to neighbouring homes and businesses?
Test connection dates against the housing programme
New electricity, water and telecommunications connections can involve network assessments, reinforcement, third-party permissions and work outside the site boundary. I would want more than an allowance in the cost plan.
For example, an all-electric housing scheme needs an electrical demand assessment that reflects its proposed heating systems and charging provision. If network reinforcement or a substation is required, that can affect land allocation, access and the construction sequence.
4. Are levels, foundations and retaining structures coordinated?
Groundworks packages can look complete individually while still failing to fit together. The drainage designer needs sufficient falls, the highways designer needs workable gradients, and the housing designer needs appropriate thresholds and external access.
This matters particularly on sloping sites. Raising a building platform might improve one drainage connection while creating a retaining wall, steeper paths or additional imported fill elsewhere.
Review the interfaces, not just the individual drawings
The project team should check finished floor levels against roads, footpaths, gardens, drainage features and neighbouring boundaries. Accessible approaches and thresholds need particular attention, with surface water managed so that convenient access does not create a route for water into the home.
I would also ask whether the foundation design accounts for nearby trees, variable ground and proposed changes in site level. Those factors need competent assessment.
- Retaining structures: Have their locations, loads, drainage and maintenance access been established?
- Boundary conditions: Could excavation or level changes affect neighbouring structures, walls or land?
- Service entries: Are ducts and drainage penetrations coordinated with foundations and any ground protection measures?
- External areas: Can paths, parking spaces and gardens be built to workable gradients without unexpected steps or walls?
Check the earthworks balance
A cut-and-fill calculation helps explain how much material must be excavated, reused, imported or removed. However, matching volumes on a spreadsheet is not enough. Material intended for reuse must be suitable for its proposed purpose, and its handling and use must meet applicable environmental requirements.
For example, soil suitable for landscaping may not be suitable as engineered fill beneath a road. The specification should define placement, compaction and verification requirements where relevant.
5. Can the groundworks be delivered safely alongside the surrounding community?
A council housing site rarely operates in isolation. It may sit beside occupied homes, a school, shops or routes residents use every day. A credible groundworks programme must allow for those surroundings rather than assuming unrestricted deliveries, generous storage space and uninterrupted working hours.
I would expect the council, as client, to understand its duties under the applicable construction health and safety regulations. In Great Britain, that includes the Construction (Design and Management) Regulations 2015.
Ask how the difficult operations will actually happen
Deep drainage, work near live services, unstable excavations and heavy plant movements need more than a generic risk assessment. The team should identify foreseeable hazards early and explain how design decisions can eliminate or reduce them.
Groundwater control deserves attention too. Pumping water from an excavation may require treatment and permission for discharge, and groundwater lowering can affect surrounding ground or structures.
Make logistics realistic
Ask the contractor to demonstrate delivery routes, vehicle turning arrangements, pedestrian segregation and emergency access. Where public footpaths or roads are affected, establish the required permissions and lead times.
On a phased estate redevelopment, I would also ask how residents will reach their homes while drainage and road works progress. Temporary routes need to remain safe, usable and clearly communicated.
6. Does the tender make costs, assumptions and responsibilities clear?
The lowest groundworks tender is not necessarily the lowest eventual cost. A price can appear competitive because it excludes disposal charges, assumes shallow excavations or leaves service diversions outside the package.
Look closely at the expensive uncertainties
The tender documents should make the scope, design responsibilities and available site information clear. Where uncertainty remains, the pricing mechanism should be explicit and appropriate to the chosen contract.
- Excavation: What assumptions have been made about depth, obstructions, support and groundwater?
- Material movements: Are testing, loading, haulage, disposal charges and imported materials included?
- Drainage and utilities: Who covers connection charges, diversions, inspections and work beyond the boundary?
- Temporary works: Are necessary design and construction costs included in the relevant package?
- Verification: Who pays for testing, surveys, records and any required remedial work?
For example, two bidders may price the same excavation volume but assume different disposal routes. Unless those assumptions are reconciled against the available material assessment, the comparison is misleading.
Agree how unexpected conditions will be managed
I would ask for a clear process covering discovery, notification, investigation and authorisation when conditions differ from expectations. The contract should govern entitlement and valuation, while the site process should ensure that evidence is recorded promptly and unsafe work does not continue simply to protect a programme date.
A council-held contingency should reflect identified risks rather than substitute for investigation. It should also remain distinguishable from contractor allowances, so the same uncertainty is not accidentally funded twice or left unfunded altogether.
7. What evidence will prove the groundworks are ready for handover?
Much of the work that determines long-term housing performance is buried before residents arrive. That makes inspection and record keeping central to quality, not an administrative exercise at the end.
Inspect critical work before it disappears
The plan should identify hold points and witness points, who must attend, and the evidence required before work proceeds. Depending on the design, this might include foundation formation inspections, reinforcement checks, drainage bedding inspections and verification of gas protection measures before they are covered.
Testing should follow the project specification and relevant approval requirements. A council should not have to rely on a general assurance that the work “passed inspection” without knowing what was checked, by whom and against which acceptance criteria.
- Earthworks records: Evidence of suitable materials, placement and specified compaction testing.
- Drainage records: Appropriate testing, surveys and confirmed as-built positions and levels.
- Environmental verification: Records demonstrating that required remediation and protective measures have been completed.
- Asset information: Accurate records of buried services, chambers, valves and other features needed for safe maintenance.
- Approvals and ownership: Inspection sign-offs, outstanding conditions and clear responsibilities for assets awaiting adoption.
Make handover useful for the people maintaining the homes
A complete handover file should help the council’s maintenance team find, inspect and look after the infrastructure. I would ask whether drawings reflect what was actually built, whether maintenance instructions are practical and whether outstanding defects have named owners and agreed completion dates.
Where roads, sewers or drainage features are intended for adoption, practical completion does not necessarily mean that adoption has occurred. The council needs to understand any remaining inspections, maintenance periods, agreements and financial obligations, alongside who remains responsible in the meantime.
For me, this final question brings the other six together. Good groundworks procurement means understanding the site, resolving design interfaces and securing evidence that the finished infrastructure will support the homes for years to come.
