Monthly Archives: January 2024

Stuart Crisp, UK manager of Advanced Drainage Systems (ADS), looks at looming legislation which will mandate Sustainable Drainage Systems and explains why their adoption will require new skills for specifiers and developers.
In January 2023, the Government announced plans to finally implement Schedule 3 of the Flood and Water Management Act 2010, which will make the adoption of Sustainable Drainage Systems (SuDS) mandatory in England, as it has been in Wales since 2019. In Scotland, Schedule 3 has not been implemented, but SuDS is generally a requirement within planning legislation.

“Schedule 3 is a game changer for the drainage industry”

Subject to consultation, the implementation of Schedule 3, which includes SuDS approval and adoption, is expected in late 2024. That means there is less than a year for specifiers and developers to get up to speed with the range and implications of possible solutions, both above and below ground.

While developers currently have the right to connect drainage systems into sewers, that is unlikely to be the case anymore without prior justification and consent. 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.

Designers and specifiers will have to think about more than just hydraulic design, and consider whole-life maintenance and treatment to deal with water quality issues and specific pollutants. There will probably be a transition period as Schedule 3 comes in, but it makes sense to upskill now in order to future-proof the design and specification of systems that are being planned now.

Currently, SuDS can be adopted by water companies as long as systems comply with the Design and Construction Guidance (DCG), which sets out how SuDS should be delivered. However, it is not compulsory to jump through the adoption hoops. The end result of this is that some assets do meet prescribed and consistent standards of quality and performance, may not be properly maintained and, consequently, there are problems down the line.

The DCG was updated last year to include arch-shaped belowground attenuation structures. One such system offers a flexible and cost-effective alternative to other below-ground attenuation structures such as crates or large-diameter pipes, with the benifit of built-in stormwater quality management, reducing the extent of additional treatment required elsewhere in the SuDS system.

It is expected that Schedule 3 will change the assessment and adoption of SuDS to become SuDS approving bodies (SABs), which will be within unitary councils or county councils. And new statutory guidance will be introduced, taking over from DCG to cover design, construction and operation over an asset’s lifetime.

The statutory requirements in England may be more onerous than both the DCG and the current non-statutory standards in terms of what will be acceptable for planning approval and adoption after construction. SuDS adoption becoming mandatory, with few exceptions, will raise the bar.

Happily, poor quality products and poorly executed designs are likely to be challenged and disappear from the market. For anyone looking to start the upskilling process now, training and CPDs are already available from some manufacturers and should include information on legislation, best practice and comparable systems.

For more information on Advanced Drainage Systems, visit www.adspipe.co.uk.

In April 2023, Defra published its so-called ‘Plan for Water’ (fully titled Our integrated plan for delivering clean and plentiful water).

The aim of the plan is to create a more holistic approach to water management, ensuring that there is enough water to supply the UK’s population, and that the water in rivers, lakes and other water bodies is free from pollution. It promises action on all sources of pollution: wastewater treatment, agriculture, plastics, urban stormwater, road run-off and chemicals.

Among the raft of proposed legislation are changes to planning policy which aim to ensure that new developments are designed to reduce the likelihood of both flooding and water shortages. Water companies, which will have to produce Drainage and Wastewater Management Plans, could be involved in planning decisions.

The Plan for Water references the Government’s intention to finally implement Schedule 3 of the Flood and Water Management Act 2010, which covers SuDS approval and adoption, in England – subject to consultation. This could make the inclusion of SuDS standard practice in the design, construction and adoption of nearly all new developments from 2024.

Should Schedule 3 of the Flood and Water Management Act come into legislation, maintenance and longevity issues will be brought to the fore. In Wales, where Schedule 3 has already been adopted, developers are expected to create a maintenance plan and the adopting authority will be required to carry out the maintenance for the lifetime of a scheme.

SuDS Approval Bodies (SABs) within county and unitary authorities will be responsible for securing the means to maintain the SuDS they adopt, and it could be that the regulatory framework in England is similar to that used in Wales. As currently understood, the developer will provide a commuted sum as funding to the SAB at the point of handover.

Run-off from roads

The Plan also talks about the strategic road network and how more is needed to prevent pollution from highway run-off discharging into water courses. There are various approaches to treat polluted run-off from roads before it is infiltrated into the ground, enters a water body or stormwater sewer, with the possibility of using SuDS as part of the water treatment train.

Run-off from roads can contain high amounts of suspended solids which sit on the bed of a watercourse, bringing with them other pollutants which are released over time. Pollutants include polycyclic aromatic hydrocarbons (PAH), metals and microplastics from brakes and tyres. The result is a build-up of toxic pollution in riverbeds, water, fish and other aquatic life.

Only 4,000 out of 26,000 outfalls and soakaways from the Strategic Road Network, run by National Highways in England, have measures in place to treat pollution. The Plan for Water mentions this and says that it is “considering actions to take to reduce the impacts of the Strategic Road Network on water quality as part of developing the next Road Investment Strategy.”

The Government will also consider ‘targeted action’ for roads owned by local authorities whose road run-off is contributing to pollution.

Nutrient pollution

The Plan for Water reports £2.5bn of planned and made investment in wastewater treatment works between 2020 and 2025, which it says will halve phosphorous pollution. And it promises legislation to force water companies to make upgrades to nutrient removal near protected habitats. The Government’s Environment Act 2021 set a legally binding target to reduce phosphorus in treated wastewater by 80% by 2038 compared to a 2020 baseline, with an interim target of 50% by 2028.

Recent studies carried out by Stormwater Shepherds indicate that phosphorus pollution is not a major problem from stormwater runoff from most urban catchment surfaces. However, well designed SuDS help alleviate nutrient pollution where it is a problem. CIRIA guide C808, Using SuDS to reduce phosphorous in surface water run-off, published in 2022, provides guidance on how to do this. Similarly, the recently published CIRIA C815, which relates to SuDS for nitrogen reduction, may be regarded as a companion document to C808.

More SuDS, better quality

With water quality concerns moving up the agenda for members of the public, as well as national and local governments, the need for well designed, constructed and maintained SuDS will only increase. Depending on parameters including application, land area available, levels of pollution and flow rates, natural SuDS, engineered SuDS or a combination of the two can be the most appropriate solution.

For more information on Advanced Drainage Systems, visit www.adspipe.co.uk.