In Wales, a six-stage standard for sustainable drainage will become mandatory
on the 7th January 2019.
Using our previous experience, we are able to design complete drainage solutions
and advise on the best form of SuDS for an area based on the infiltration of the ground
and the potential impacts on ground stability.
Surface Water Runoff Destination
A hierarchical assessment of surface water run-off destination
Priority Level 1: Surface water runoff is collected for use
Priority Level 2: Surface water runoff is infiltrated into the ground
Priority Level 3: Surface water runoff is discharged to a surface water body
Priority Level 4: Surface water runoff is discharged to a surface water sewer
Priority Level 5: Surface water runoff is discharged to a combined sewer
Surface Water Runoff Hydraulic Control
Flow input control:
Delaying the discharge of surface water to the watercourse by providing storage within ponds, retention basins, amenity lakes and wetlands.
Decreasing the volume of water entering the drainage system.
This method is achieved by placing a flow control at the outlet where the drainage layer can be stored and attenuate the water. The roof building design is partially or completely covered with vegetation or another growing medium.
Channels and Rills
The roof of a building that is partially or completely covered with vegetation or another growing medium.
By placing a flow control at the outlet, the drainage layer can store and attenuate water.
Suitable treatment of run-off through the use of SuDS.
These filter drains are shallow excavations filled with rubble or stone that create temporary subsurface storage of stormwater runoff. These trenches can be used to filter and convey stormwater to downstream SuDS components. As a result, they should ideally receive lateral flow from an adjacent impermeable surface.
Ensure the drainage system provides amenity value to future users.
It should be considered at the early master planning stage or similar juncture.
Stone-filled trenches which allow water to soak into the ground, as close
to where the rain lands as possible, or flow is conveyed laterally to a point
Ensure that drainage strategy provides biodiversity potential. it should be considered at the early master planning stage or similar juncture.
A small water body with an open water area and marginal wetland around the edge. Provides excellent amenity features and can act as site control as a cost-effective way of providing storage.
Detailed design suitable for SAB approval.