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Services  /  Drainage & Site Engineering
Service 05

Drainage & Site
Engineering, managed at source.

End-to-end stormwater drainage design, sustainable drainage systems and site grading — managing runoff at source to create flood-resilient, regulation-compliant site layouts for solar, industrial and commercial projects.

SuDS designStormwaterLand gradingDTM analysisSolar sites7–14 days
At a glance
7–14 days
Standard delivery
SuDS
Design standard
DTM
Terrain analysis
Every study includes
  • Stormwater drainage system design & capacity analysis
  • Sustainable Drainage Systems — swales, basins, rain gardens
  • Land levelling & grading design for optimal water flow
  • Cut/fill optimisation & earthwork volume calculations
  • Named engineer · Post-delivery support
SuDS
Design approach
DTM
Terrain modelling
QGIS/ArcGIS
GIS tools
7–14 days
Delivery
What it is

Drainage & Site Engineering — what HYDRisk delivers.

Drainage and site engineering is the practical engineering translation of flood risk findings into physical design. Where an FRA identifies flood hazard, drainage design provides the engineering solution — managing how surface water is collected, conveyed, attenuated and discharged in a way that protects the site and its surroundings.

HYDRisk drainage studies cover the full spectrum from stormwater network design for solar and industrial sites to sustainable drainage system (SuDS) design for residential and mixed-use developments. Every drainage design is based on the same hydrological analysis used in our flood risk assessments.

Land levelling and grading design is integral to our drainage service — critical for solar farm sites where panel elevation, foundation levels and surface water runoff must be coordinated. We produce Digital Terrain Models (DTMs) and cut/fill calculations that optimise earthworks while ensuring effective drainage across the site.

All HYDRisk drainage designs are produced in GIS and CAD formats compatible with your engineering team — and are fully integrated with any FRA, hydraulic model or watershed analysis produced for the same site.

Why drainage design matters
“Flood risk assessment identifies the problem. Drainage design provides the engineering solution.”
Integrated with FRA findings
Full DTM & cut/fill design included
SuDS specification to local standards
GIS/CAD outputs ready for engineering handoff
Why it matters

Four reasons this service is critical to your project.

Understanding what this study delivers — and what happens without it — is the fastest way to evaluate whether your project needs it.

Poor drainage causes flooding without any river event
Insufficient drainage capacity and poor grading lead to operational disruption, equipment damage and access failures even with zero river or coastal flooding.
Solar farm drainage is a specialist discipline
Large-footprint solar sites generate significant runoff. Without proper design, runoff concentrates in low points, eroding foundations and blocking access.
SuDS requirements are becoming mandatory
Sustainable Drainage Systems are increasingly required under green infrastructure programmes. Early design is far cheaper than retrofitting post-construction.
Poor grading multiplies earthwork cost
Without an optimised DTM and cut/fill plan, sites over-excavate or under-drain — inflating earthworks budgets unnecessarily.
What we deliver

Specific deliverables — not vague promises.

Every HYDRisk study produces a defined set of technical outputs — here is exactly what you receive.

Technical design outputs
  • Stormwater drainage network design — pipes, channels, structures
  • Drainage capacity calculations — all required return period storms
  • SuDS design — swales, rain gardens, retention basins, permeable paving
  • Surface water management plan — attenuation and discharge rates
  • Land levelling & grading design — finished surface level contours
  • Cut/fill calculations — earthwork volumes and optimisation
GIS, CAD & report deliverables
  • Drainage design report — methodology, calculations, specifications
  • Drainage layout drawings — AutoCAD DXF or PDF format
  • DTM (Digital Terrain Model) — existing and proposed surface levels
  • Grading plan — finished level contours and drainage gradients
  • SuDS design drawings — location, sizing and specification
  • GIS spatial data — drainage network and SuDS features in Shapefile
Deliverable formats: Design report in PDF. Drawings in AutoCAD DXF and PDF. GIS data in Shapefile and GeoTIFF. DTM surfaces in compatible formats for engineering design software.
Request a scope →
Tools & methodology

Industry-standard tools. Region-specific data.

Every tool we use is the same software trusted by government agencies, major engineering firms and regulatory bodies worldwide.

SWMM / InfoWorks
US EPA / Autodesk
Urban stormwater modelling for drainage network design and capacity analysis, and SuDS performance assessment.
Stormwater networkSuDS modelling
HEC-HMS
US Army Corps of Engineers
Hydrological modelling providing runoff volumes and peak discharge inputs to drainage design calculations.
Runoff volumesDesign storms
QGIS / ArcGIS
Open Source / Esri
Digital terrain modelling, slope analysis and grading design production for site-wide drainage planning.
DTM productionSlope analysis

Step-by-step methodology

Step 01
Site data collection
DEM terrain data, existing drainage infrastructure, planning requirements, design storm specifications.
Step 02
Hydrological analysis
Runoff volume and peak flow estimation for all design storms using HEC-HMS or rational method.
Step 03
Drainage system design
Pipe and channel sizing, gradient design, inlet/outlet structures. SuDS element sizing and placement.
Step 04
Grading & DTM design
Digital terrain modelling. Finished level design for optimal drainage flow. Cut/fill calculations.
Step 05
SuDS design (if applicable)
Swale, retention basin or rain garden design. Infiltration testing requirements. Maintenance plan outline.
Step 06
Drawings & report
Drainage design report with calculations. AutoCAD layout drawings. GIS data. Grading plan. SuDS specification.
Regional applicability

Calibrated for your region and regulatory framework.

Methodology, data sources and regulatory requirements differ between geographies. HYDRisk delivers the right approach for every region.

United States — Primary market
NOAA-aligned methodology
NOAA rainfall, state stormwater manuals, EPA NPDES compliance.
Regulatory frameworks
EPA NPDESState stormwater manuals
  • NOAA Atlas 14 design storm frequency
  • State-specific stormwater manual compliance
  • EPA NPDES construction/post-construction runoff standards
Middle East & GCC
GCC-specific methodology
Arid-region drainage sizing, wadi discharge management, GCC municipal compliance.
Regulatory frameworks
UAE MunicipalityAshghal (Qatar)
  • Arid-region drainage sizing standards
  • Wadi and flash-flood discharge management
  • UAE, Saudi Arabia, Qatar municipal compliance
International
Global drainage methodology
EU Water Framework Directive-aligned SuDS, IFC PS1/PS4-ready reporting.
Regulatory frameworks
IFC PS1 & PS4EU Water Framework
  • EU Water Framework Directive-aligned SuDS design
  • IFC PS1/PS4-ready site engineering reporting
  • Remote delivery — any geography covered
Related services

Services often commissioned alongside this study.

Service 01
Flood Risk Assessment
Drainage design is often the engineering response to flood risk findings — procured as an integrated package with the FRA.
View service →
Service 02
Solar PV Flood Risk
Solar farm drainage design is frequently commissioned alongside the solar FRA for a complete site water management solution.
View service →
Service 09
Flood Mitigation & Protection
Where site drainage alone is insufficient, flood mitigation measures are designed in coordination with drainage engineering.
View service →

Ready to commission a drainage study?

Tell us your site type, size, and drainage requirements. We will recommend the right approach and scope the work within 24 hours.

Get a free consultation →
Proposal within 24hFixed-fee pricingNo obligation