Construction-Phase Drainage • Silt & Pollution Control • CIRIA Guidance

Construction Surface Water Management Plans Protecting Watercourses During the Build

Condition requiring a Construction Surface Water Management Plan? We prepare phased plans that control runoff, silt and pollution during construction — essential where works are near a watercourse, SSSI or sensitive receptor.

Get a Free Quote 07826 705389 Email Us
✓
Phased construction drainage
✓
Silt & sediment control
✓
Pollution prevention
✓
Dewatering & discharge
✓
SSSI & watercourse sites

Construction Surface Water Management Plans (CSWMP)

During construction, stripped ground and stockpiles generate silt-laden runoff that can pollute nearby watercourses and breach environmental law. Where a site is near a watercourse, a designated site such as an SSSI, or any sensitive receptor, the LPA, Environment Agency or Natural England will often require a Construction Surface Water Management Plan — secured by condition — before works begin.

We prepare a phased plan setting out how surface water, silt and potential pollutants are managed across each stage of the build: interception and settlement of runoff, silt control measures, pollution prevention, controlled dewatering and discharge, and monitoring. The plan follows recognised CIRIA guidance and the Environment Agency’s pollution prevention principles, and is written to discharge the condition and keep you compliant on site.

What’s Included

  • ✓ Phased surface water management — how runoff is controlled at each construction stage, from strip to completion
  • ✓ Silt & sediment control — settlement, interceptor and filtration measures to stop silt reaching watercourses
  • ✓ Pollution prevention — fuel, concrete and material storage controls following EA pollution prevention guidance
  • ✓ Dewatering & discharge — controlled discharge arrangements and where a permit or consent is required
  • ✓ Sensitive receptor protection — specific measures where an SSSI, main river or protected habitat is nearby
  • ✓ Monitoring & responsibilities — inspection regime, trigger actions and spill response, with roles assigned
Construction earthworks Works adjacent to a watercourse Surface water management on site

When Is a CSWMP Required?

Works near water or a protected site? Send us the location and we’ll advise.

Conditioned Before Commencement

A condition requiring a construction surface water or environmental management plan to be approved before works begin — the usual trigger.

Sites Near a Watercourse

Where runoff could reach a river, stream or drain, silt and pollution control during the build is essential and expected.

SSSI & Protected Habitats

Sites near designated nature conservation sites attract Natural England interest and require robust construction-phase controls.

Large Earthworks

Extensive cut, fill and stockpiling generates significant silt-laden runoff that must be intercepted and settled.

EA / NE Objection Risk

Where the Environment Agency or Natural England has flagged construction-phase water quality, a sound CSWMP resolves it.

Part of a CEMP

The surface water element of a wider Construction Environmental Management Plan, which we can prepare or contribute to.

What a Construction Surface Water Management Plan Covers

Controlling run-off, silt and pollution while the site is being built.

The construction phase is often when a site causes the most flooding and pollution — stripped ground, stockpiles and half-built drainage all shed silt-laden water fast. A Construction Surface Water Management Plan (CSWMP) sets out how run-off will be controlled during the works, and is increasingly required by planning condition, by the Environment Agency for sites near watercourses, and by the LLFA.

Temporary drainage & storage

How run-off is captured and attenuated during construction — temporary basins, cut-off ditches and the sequencing of permanent drainage so it can be used early.

Silt & pollution control

Silt fences, settlement lagoons, wheel washes and fuel storage controls to stop sediment and contaminants reaching drains and watercourses, drawing on CIRIA construction-phase guidance.

Phasing & responsibilities

A plan matched to the build programme, with named responsibilities, monitoring and the actions to take in heavy rainfall or a pollution incident.

Frequently Asked Questions

What is a Construction Surface Water Management Plan?
It’s a plan that controls surface water runoff, silt and pollution risk during the construction phase of a development — protecting nearby watercourses and habitats until the permanent drainage is in place.
How does it differ from a CEMP?
A Construction Environmental Management Plan (CEMP) covers all environmental aspects of construction; the CSWMP is the surface water and pollution-prevention element. We can provide the CSWMP alone or as part of a CEMP.
Why does proximity to a watercourse or SSSI matter?
Silt and contaminants in construction runoff can seriously harm aquatic ecology and breach environmental law. Sensitive receptors raise the bar for the controls required, and the EA or Natural England will scrutinise the plan.
Do I need a discharge consent for dewatering?
Sometimes. Discharging water pumped from excavations to a watercourse or sewer can require a permit or consent. We identify what’s needed and the controls to keep the discharge clean.
How much does it cost?
A fixed fee that depends on site size and sensitivity. We’ll quote within 24 hours of seeing the location and the condition wording.
When is a construction surface water management plan required?
Typically where a planning condition requires one, where the Environment Agency has concerns about a nearby watercourse, on larger or steeper sites, or where the LLFA wants assurance that the construction phase will not increase flood risk. It is also good practice on any site with significant earthworks.
Who checks and enforces the plan?
The LLFA or LPA discharges the condition, and the Environment Agency can take enforcement action if silt or pollution reaches a watercourse. A credible, site-specific plan protects you on both fronts.
How does it relate to the permanent drainage strategy?
The CSWMP is the temporary counterpart of the permanent SuDS strategy. Where possible we sequence the works so permanent attenuation features are built early and used to control run-off during construction.

Get a Free Quote

Free, no-obligation fixed-fee quote within 24 hours. All flood zones and LLFAs covered across England and Wales.

Get a Free Quote

Or contact us directly: 07826 705389  •