Utilities & drainage infrastructure
Surface water and foul drainage must integrate with groundworks sequencing and adoption requirements. We install attenuation, soakaways and drainage runs to design with clear testing and handover.
Stakeholders include developers, drainage engineers, water companies, adopting authorities and main contractors managing S104 programmes. Challenges include gradient control, adoption testing, interface with earthworks and protecting drainage during subsequent construction.
Mainline coordinates utilities and drainage groundworks with wider civils programmes — attenuation, adoptable sewers, plot connections and SuDS features delivered with buildability and inspection readiness.
Drainage and utilities infrastructure groundworks
Utilities and drainage infrastructure groundworks cover the physical installation of foul and surface water systems, attenuation, soakaways, manholes, pumping interfaces and the adoptable sewer networks that connect developments to statutory undertakers. These packages must align with drainage strategy, earthworks levels and the adoption programme.
Procurement often follows drainage strategy approval. Developers may let a dedicated drainage subcontractor, combine drainage with roads and sewers, or procure attenuation separately from plot connections. Design-and-build drainage routes require buildability input during detailed design.
Typical requirements include foul sewer laying, surface water sewers and gullies, attenuation crates and tanks, flow control structures, soakaway construction, manhole and chamber builds, pressure testing and CCTV, plot connection laterals, and coordination with bulk earthworks so invert levels are protected.
Regulatory considerations include S104 Water Industry Act adoption, planning drainage conditions, SuDS hierarchy compliance, environmental discharge permits where applicable, and building control on plot connections. Testing and CCTV records are adoption gates — poor records delay sewer transfer.
Mainline delivers drainage and utilities groundworks integrated with wider civils sequencing. We support Section 104 adoption routes, SuDS installation and plot drainage with testing, records and handover aligned to water company and adopting authority requirements.
Typical projects
Representative project types we deliver in this sector.
Attenuation schemes
Crate and tank storage, flow controls and overflow routes on development sites.
Adoptable sewer networks
S104 foul and surface water sewers with testing and CCTV handover.
SuDS features
Swales, permeable paving interfaces and green drainage integration.
Plot drainage connections
Lateral connections from plots to adoptable foul and surface water networks.
Services delivered
Groundworks and civils services relevant to utilities projects.
Attenuation System Contractors
Storage systems, flow control and SuDS buildability on development sites.
View service →Commercial Drainage Contractors
Foul and surface water drainage runs, chambers and adoptable networks.
View service →Roads and Sewers Contractors
Combined estate roads and adoptable sewer infrastructure packages.
View service →Section 104 Contractors
S104 adoption packages with testing, CCTV and authority coordination.
View service →Excavation Contractors
Trenching and excavation for deep drainage and utility corridors.
View service →Bulk Earthworks
Formation levels coordinated with drainage gradients and attenuation placement.
View service →Site Preparation Contractors
Early site preparation ahead of main drainage mobilisation.
View service →Groundworks Contractors
Integrated groundworks with drainage as a coordinated package.
View service →
How drainage infrastructure is procured
Drainage packages are procured against approved drainage strategy and adoption programme status. Separating or combining drainage with roads and earthworks affects risk, sequencing and tender comparability.
Dedicated drainage subcontract
Specialist drainage contractor appointed for S104 and attenuation packages.
Combined roads & sewers
Single contractor for adoptable roads and sewer infrastructure.
Developer direct
Developer appoints drainage contractor for adoption programme control.
Design & build drainage
Contractor input on buildability during detailed drainage design.
Competitive tender
Fixed price against drainage strategy, levels and adoption correspondence.
Why Mainline
How we reduce interface risk and deliver programme-led groundworks in this sector.
Drainage expertise
Foul, surface water and attenuation packages to engineer and authority standards.
Adoption-ready records
Testing, CCTV and as-builts structured for S104 handover.
Sequencing with civils
Drainage coordinated with earthworks, roads and plot release programmes.
Buildability input
Practical installation sequencing during detailed design development.
Testing discipline
Pressure testing and inspection coordination before backfill and adoption.
Development experience
Drainage on housing, commercial and infrastructure-led schemes.
Project delivery process
A structured approach from first enquiry through to handover.
- 1
Enquiry
Share your site location, programme, drawings and procurement route. We confirm scope fit and the information needed for a commercial return.
- 2
Scope review
We review formation levels, drainage strategy, adoption requirements, access constraints and interfaces with the wider design team.
- 3
Pricing & programme
You receive a priced package with sequencing assumptions, mobilisation plan and key commercial clarifications before award.
- 4
Site delivery
Groundworks are executed with QA checks, inspection coordination and programme reporting aligned to your site management processes.
- 5
Completion & handover
Testing, as-built records and formal handover are completed so the next trade or adoption milestone can proceed without delay.
Related case studies
Project examples from this sector will be published here.
| Project | Location | Value | Services delivered |
|---|---|---|---|
| Case studies coming soon | — | — | Groundworks packages will be published here as projects complete. |
Planning & technical guides
Resources to support procurement, design and commercial planning in this sector.
Soakaway design and installation
Soakaway sizing, construction and testing.
Green drainage (SuDS)
SuDS hierarchy and green drainage on developments.
Surface water drainage installation
Installing surface water systems on site.
Drainage adoption (Section 104)
S104 adoption process and requirements.
Attenuation systems for developers
Attenuation sizing and commercial planning.
Planning drainage for new housing
Drainage strategy on residential schemes.
Commercial drainage explained
Foul and surface water on commercial sites.
Drainage adoption process
End-to-end adoption programme management.
Foul drainage for new build
Foul sewer design and installation.
Installing soakaways
Soakaway construction on new-build plots.
Utilities & drainage infrastructure — frequently asked questions
Common questions about groundworks delivery in this sector.
Do you install attenuation and SuDS features?
Yes. We install crate and tank attenuation, flow controls and SuDS features aligned to drainage strategy.
Can you deliver S104 adoptable sewers?
We deliver adoptable foul and surface water packages with testing, CCTV and authority coordination.
How is drainage sequenced with earthworks?
Invert levels and attenuation placement are coordinated with formation works to avoid rework and protect gradients.
What testing is provided for adoption?
Pressure testing, CCTV and records are completed to meet water company and adopting authority requirements.
Can drainage be combined with roads packages?
Yes. Combined roads-and-sewers packages are common where adoption programmes align.
Need drainage and utilities groundworks support?
Speak with our team about attenuation, adoptable sewers, SuDS and plot drainage on your development.