New guidance for construction site drainage to surface waters

Earlier this year new guidance was issued detailing the regulatory position on the transfer of water from construction sites to rivers and streams.

It states that only uncontaminated water consisting of clean and clear rainwater or infiltrated groundwater may be released from a site for up to three consecutive months under exemption.

frog environmental specialise in water management and silt control. We can help you at all stages in your project including pre-tender advice.

In order to qualify for the exemption a series of conditions aimed to prevent pollution in the receiving water body must be met. Consequently, the discharge must not:

  • result in muddy water
  • contain any chemical agent such as a coagulant or flocculant
  • contain any contaminant such as oil
  • contain concrete wash water even if it has been treated
  • contain site drainage from surfaces such as haul roads, storage areas
  • spread invasive plants animals or diseases
  • be within or close to a sensitive ecological site

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A method statement must document the control measures to minimise the risk of pollution such as how to:

  • minimise water entering the excavation such as from rainfall or runoff
  • minimise the level of contaminants being generated such as silt
  • dispose of water that enters the excavation including any silt control interventions

Where any of the above cannot be complied with then a BESPOKE ENVIRONMENTAL PERMIT is required.

What does this actually mean in practice?

All sites should implement a basic water management plan to illustrate how they are controlling the risk of pollution, protecting the aquatic environment from the ingress of material such as soil, silt, oil, chemicals or concrete wash waters.

However, the reality is that following the new guidance, the majority of UK construction projects will need to hold a Bespoke Environmental Permit for the drainage of site waters into a stream, river or to ground.



Emergency silt response kit

  • discharge mechanism and rate from site as well as the flow rate of the receiving water
  • potentially sensitive environmental and human receptors
  • pollution source and pathway assessment including aspects such as contaminated land, working near water, haul roads and
  • earthworks
  • pollution control mechanisms
  • surface water analysis to complete the prescribed regulatory risk assessment screen tests

It is recommended that you engage with the local regulatory team early in the process as the determination of a permit application can be lengthy taking up to 14 weeks.

Sites that do not hold a permit are vulnerable to regulatory action. Where pollution occurs, there is the risk of enforcement action including a fine or custodial sentence, plus the loss of reputational benefit. Equally, any unplanned remedial measures may affect the operation of a site and delay or even stop works.

Don’t panic! We can help. frog environmental specialise in water management and silt control. We are able to help you at all stages in your project including pre-tender advice.

We act for and guide construction companies of all shapes and sizes and pride ourselves on offering practical, site specific and customer focussed solutions.

Our services include:

  • Site Review – For numerous clients we carry out a short site review and letter reporting process. This is designed to outline risks of silt pollution from site, identify control measures and permitting requirements
  • Silt Control Products – We supply silt management products made from natural sustainable materials including Silt Mats, Wattles and Floc Mats™ to reduce and even prevent silty run-off. Bubble Curtains can be used in watercourses to limit downstream pollution whilst our WaterLynx™ flocculants designed to help remove fine clay particles from muddy water have secured regulatory approval for their use in some of the most sensitive UK environments.
  • Water Management Planning – We risk assess developments and create Pollution Risk Assessment and Pollution Control documentation, to form your site water management plan.

Next Steps

Contact us 

Email us
Call us 0345 057 40 40
Follow us @frogenv

Further Reading

Environment Agency guidance for England has also been adopted by Natural Resources Wales and is introduced in the form of a “Regulatory Position Statement

A similar outlook in Northern Ireland Department of Agriculture, Environment and Rural Affairs

In Scotland, “General Binding Rules” have long been applied by the Scottish Environment Protection Agency and bring similar requirements

At frog we specialise in bespoke, practical solutions.

Here a series of silt mats, flocculant treated mats and silt wattles have been used to create a highly effective, low cost, gravity fed silt treatment process


Gravity fed silt capture channel