Construction phase SuDS

Construction phase SuDS are used to control and remove silt from the runoff while construction work is ongoing.

When planning your site and the phases of work, make sure that you include enough land to be used for construction phase SuDS. This land needs to be chosen to make sure that there is enough capacity for dealing with potentially silt laden runoff, and is in a suitable location.

Your SuDS should be:

  • Situated away from flood plains
  • Large enough to deal with the volume of runoff that can be expected from the area of your site
  • Constructed away from any areas likely to become flooded by any means.

Avoid stripping large areas of your site and minimise the areas of exposed soil. Keep soil exposed for as short a time as possible. This will minimise the amount of silt laden run-off. Less silt laden water will reduce the risk of water pollution. 

Use cut off ditches to redirect clean run-off water away from working area to avoid overwhelming the SuDS treatment system with ‘clean’ water.

You should avoid using final phase SuDS during the construction phase. They are likely to receive a lot of sediment and silt and this would prevent them operating effectively once the construction is completed.

If they have to be used, for example because of limited space, make sure that remediation work is carried out to return them to good condition once construction work is completed. This could mean removing silt build up in swales and retention ponds or replacing or cleaning gravel in filter drains.

In Scotland you must comply with the General Binding Rules (GBRs) for discharges of run-off water (GBR 10 and 11)

GBR 10 - Discharging water from a surface water drainage system 

From 01 January 2018, GBR 10 was updated to cover surface water discharge from:

  • land used for residential purposes (up to 60 hectares).
  • land used for non-residential premises or yards (excluding industrial estates).
  • car parks with up to 1,000 spaces.
  • metalled roads (excluding motorways and A roads).
  • waterbound roads.

and

  • constructions sites, where the site, including any constructed access tracks does not:
    • exceed 4 hectares.
    • contain a road or track longer than 5km.
    • include any area more than 1 hectare, or any length of more than 500m on ground with a slope of more than 25°. 

If your site exceeds these thresholds then you will require authorisation from SEPA, see SEPA : Construction site licences

GBR 10 specifies that all reasonable steps must be taken to ensure pollution does not occur.

The discharge must not:

  • contain trade effluent/sewage.
  • result in discolouration, iridescence, foaming or growth sewage fungus.
  • destabilise banks or bed of the receiving surface water.
  • contain run-off from fuel delivery areas, vehicle loading/unloading bays where potentially polluting matter is handled or oil and chemical storage, delivery and handling areas. if constructed on or after 1st April 2007.

All parts of the surface water drainage system must be maintained in good working order and repair and steps must be taken to ensure that matter liable to block or obstruct the drainage system is prevented from entering.

Further information

Return to the menu of the Control of water pollution from construction sites environmental topic