Drainage Solutions for Commercial Development

SEL have a wide range of Sustainable Drainage Solutions for Retail, Warehousing, Industrial,Leisure and School Developments as listed below:-

  • Car Park Drainage 
  • Roof Water Attenuation 
  • Soakaway & Infiltration 
  • Rain Water Recycling
  • Permeable Pavements
  • Impermeable Membranes

All the above solutions take advantage of the principles of Sustainable Drainage (SuDS) and where required will incorporate a series of treatment phases specifically developed to provide the ideal source control solution to meet the requirements of all current guidelines and legislation relating to SUDS. The main design principle of the SEL Source Control Systems is to use Source Control, a cornerstone of good Sustainable Design.

Why Source Control?

Source Control is the treatment and controlled release of storm water runoff at or very near its source. Source Control is the preferred technique for the implementation of SUDS according to the Interim Code of Practice for Sustainable Drainage Systems, PPS25 and PPG3.

Aquacell, attenuation, brownfield, car park, car park drainage, catchpit chamber, charcon, contaminated land, cut off trench, flow control, flow control chamber, gas barrier, gas membrane, gas protection, gas venting, geomembrane, geotextile, hdpe, headwall, hydrocarbon, infiltration, interceptor, ldpe, membrane, membrane welder, methane, passive venting, permavoid, plastic tank, polypipe, polystorm, pp, rain water recycling, rain water re-use, rainwater recycling, rainwater re-use, remediation, silt catchpit chamber, Skeletank, soakaway, source control, suds, surface water, drainage, surface water storage, surface water tank, surfacewater drainage, surfacewater storage, surfacewater tank, sustainable car park drainage, sustainable drainage, tank, vent bollard, vent stack, vent trench, welded membrane

Techniques Considered

  1. The SEL Car Park Drainage System provides infiltration or attenuation, incorporating multiple stages of water treatment and flow control within the constructed layers of the car park and hardstandings, directly beneath the finished surface, more...

  2. The Roof Water Attenuation system comprises individual modular units assembled together to form an underground voided structure which can  soakaway or attenuate roof water. These structures are situated around the building and used to store and convey the run-off, more...

Permavoid Sub-base Replacement System

The Permavoid geocellular system is ideal for the management of surfacewater drainage attenuation, extends the choice and flexibility for sustainable drainage solutions (suds) by providing robust, effective source control through attenuation or soakaway at shallower levels.

Permavoid is designed to be used in place of a traditional aggregate sub-base within trafficked pavements and provides a unique high strength, consistent structural raft with all the associated benefits of highly voided modular geocellular structure.


Permachannel functions as a combined run-off collection, silt/oil interceptor and treatment component within the Permavoid System. Ideally it is laid with zero gradient to prevent lateral velocities, ‘stilling’ sheet run-off from each sub-catchment and encouraging silt deposition within each channel.

The outlets discharge from the side of the channel via a weir and baffle component, which separates oils and prevents effluent and silt from progressing beyond the channel into the rest of the drainage system.


Permachannel is used for stormwater collection, interception and treatment of associated pollutants. The system comprises of single or multiple interconnected channels appropriately located to collect surface water run-off from sub-catchments of either impervious or pervious pavements. Permachannel is suitable for use in a range of applications including residential, industrial estates, car parks, sports pitches, roofs, basements, pedestrian areas and rainwater harvesting.


Permachannel is rated to D400 loading in accordance with BS EN 124:1994 when installed with concrete bed and haunch in accordance with site specific construction details.

Installation Standard 

Permachannel must be installed on a load bearing concrete bed and haunch, in accordance with site specific construction details.

Features & Benefits

  • Gravity separation of oils and silts at source
  • Trapped effluent naturally treated by aerobic digestion
  • Can enhance water quality and eliminate the need for end of line petrol/oil interceptors
  • Can reduce hydrocarbon pollution loading below 5mg/l
  • The system complies with the regulations of the treatment train criteria in a SuDS scheme as defined in PPG3
  • 100% recyclable

Health & Safety

SEL Drainage Solutions can satisfy the designers’ statutory obligations as required by the Construction Design and Management (CDM) regulations. Using a SEL Drainage Solutions could help you avoid the risks inherent with traditional drainage systems such as:- Operatives working in deep excavations where there is risk of collapse Heavy lifting operations Operatives working within confined spaces Operatives exposure to contaminated sub-strata The SEL Source Control System avoids these foreseeable risks because it is shallow (generally less than 500mm deep), lightweight, installed above formation levels and contaminated zones.

Technical Services

To support architects, engineers and contractors in designing and installing the an SEL Drainage Solution, we can provide computer aided scheme design, hydraulic performance calculations and technical advice on products and installation. Supply and install packages are available for elements of the system. Information is available on request.