Sustainable Drainage Systems In Sewers - A New Approach

Sustainable Drainage Systems (SuDS) are likely to become more commonplace in sewer applications after the new sewerage adoption arrangements that have come into effect after April 2020. We’re here to clear up any potential confusion and explain what these new arrangements are, how they have come into place and what this means for the future of sewers and SuDS.

Why are SuDs going to become more popular in sewers?

Proceeding the government’s rejection to implement Schedule 3 of the Flood and Water Management Act 2010, water companies both big and small are now contemplating their position in regard to the adoption of Sustainable Drainage Systems (SuDS). This is due to the fact that the implementation of this schedule would have presented a comprehensive regime for surface water drainage as well as resulted in a mandatory Sewers for Adoption manual, which is currently voluntary.

Although the sewers for adoption manual remains voluntary, the revisions that were going to be put in place regarding adopting sewers have instead been implemented into Ofwat’s Code for Adoption Agreements, a statutory code that requires the UK water sector to prepare new mandatory guidance on sewerage asset adoption to those in sewer construction. This is essentially as good as government guidance and must include the Design and Construction Guidance (DCG) document. The DCG outlines the UK water sector’s new approach to the adoption of sustainable drainage systems that meet the specifications of a legal sewer system.

As previously mentioned, the introduction of these new arrangements was implemented into the code on 1st April 2020 and in order to make this transition as smooth as possible, state applications with the current standards will still be accepted up until a maximum of six months from the introduction date. Alongside this, any reporting on against the new performance metrics will also be delayed for the same duration, as noted in the Sewerage Sector Guidance Document (SSG) by WaterUK.

What are the benefits of sustainable drainage in sewers?

In recent years, drainage engineers, environmental NGOs and the government have started leaning more and more towards the view that there are now more efficient and environmentally friendly methods of dealing with surface water drainage than traditional sewerage systems; the most prominent method being SuDS. The SSG document states that the aforementioned parties would now prefer if surface water is allowed to infiltrate into the ground as opposed to flowing directly into a piped sewer system.

SuDS provide a large range of benefits over traditional sewer systems such as reducing the risk of sewer pipes overflowing after heavy rainfall, increasing the amenity value of an area as SuDS absorb pollutants in water and create green spaces, and allowing for increased housing development as less space is required.

The SSG brochure provides an outline of all of the new rules regarding surface water sewers, and the DCG document provides further information on all legal sewerage systems, including new options that feature sustainable elements.