Designers of new developments must start to factor in government requirements for sustainable drainage systems which are due to come into effect soon.

With legislation mandating sustainable drainage systems (SuDS) and their adoption for new developments on the horizon, developers and designers must upskill to ensure future designs meet tough new standards.

The government’s recent announcement that it intends to implement Schedule 3 of the Flood and Water Management Act 2010, is a game changer for SuDS.

It means that SuDS adoption is expected to be mandatory in England, as it has been in Wales since 2019.

In Scotland, Schedule 3 has not been implemented, but SuDS are generally a requirement within planning legislation.

“While developers currently have the right to connect drainage systems into sewers, that is unlikely to be the case anymore,” explains Advanced Drainage Systems (ADS) UK manager Stuart Crisp.

“Instead, they will have to show that they have included SuDS in their schemes and demonstrate how that SuDS system can be maintained over the lifetime of a development.”

Subject to a consultation later this year, implementation of Schedule 3, which includes SuDS approval and adoption, is expected in late 2024.

That means that engineers have less than two years to get up to speed with the range of possible solutions above and below ground and the implications those bring.

“Designers will have to think about more than just hydraulic design, to include whole life maintenance and treatment to deal with water quality issues and specific pollutants,” says Crisp. “There will probably be a transition period as Schedule 3 comes in, but it makes sense to upskill now in order to future proof designs.”

Currently, SuDS can be adopted by water companies as long as systems comply with requirements in the Design and Construction Guidance (DCG) document which sets out how SuDS should be delivered. However, it is not compulsory for a developer to jump through the adoption hoops, leading to the use of some assets which are not a prescribed, consistent standard of quality and performance or which are not properly maintained and monitored, leading to problems down the line.

The DCG was updated last year to include arch-shaped, below-ground attenuation structures, such as ADS’s StormTech. StormTech offers a flexible and cost-efficient alternative to other below- ground attenuation structures such as crates or large diameter pipes. It has built-in pollution treatment, reducing the extent of additional treatment required elsewhere in the SuDS system.

It is expected that Schedule 3 will change the adopters of SuDS to become SuDS approving bodies (SABs), in line with the Welsh approach, which will be within unitary councils or county councils.

The change will bring in new statutory guidance, taking over from the DCG to cover design, construction and operation over an asset’s lifetime.

“The statutory requirements in England are likely to be more onerous than the DCG and the current non-statutory standards in terms of what will be acceptable for planning approval and adoption after construction,” warns Crisp. “SuDS adoption becoming mandatory, with few exceptions, will raise the bar. Happily, poor quality products and poorly executed designs are likely to disappear from the market.”

For anyone looking to start the upskilling process now, manufacturer training and continuing professional development, such as those on below-ground attenuation offered by ADS, are already available and should include information on legislation, best practice and comparable systems.