Chris Adair of Marshalls explains how contractors can navigate biodiversity net gain (BNG) legislation
In the past, ensuring a residential site achieves biodiversity net gain (BNG) has been something only major developers have needed to think about. But since April this year, BNG applies to smaller developments in England too, meaning multi-plot sites with one to nine dwellings now need to meet the criteria.
At the same time, we’re moving closer to the full adoption of Schedule 3 of the Flood and Water Management Act. It focuses on managing water runoff in the most natural way possible, slowing down the release of water and improving its quality, while trying to benefit the local wildlife and improve the environment for the local population. This contrasts with more traditional drainage systems, which concentrate on the removal of surface water as quickly as possible.
Schedule 3 of the Act currently focuses on developments with more than 10 homes, but when the Act becomes compulsory, it is likely to be broadened to smaller sites too.
This means in the near future, builders working on multi-plot developments will have to consider how to balance sustainable drainage solutions (SUDs) with BNG to create developments that meet two sets of legislation at the same time.
Two-step change
In practice, BNG means that new developments need to improve the biodiversity of a site by at least 10% versus how it was before development. That could be achieved by creating new wildlife habitats, increasing the amount of green space available, or adding SUDs features which include opportunities for plant and animal life to establish themselves.. And while the inclusion of SUDs in place in new building projects has previously been at the developer’s discretion, Schedule 3 will dictate more about drainage plans than before.
Moving forward, key solutions for builders will be those that manage the amount of water entering the sewer systems, while also adding natural beauty and biodiversity to the local landscape. This is where a new modular rain garden kerb system, soon to be available from Marshalls, comes in.
Innovative take on water management solutions
Doubling up as an attractive, biodiverse feature which also acts as a flood management system, rain gardens have become a key element in housing developments in recent years.
Rain gardens use plants and soil to retain and slow the flow of rainwater from surrounding hard surfaces. Often, these are combined with a kerb, where water flows into the garden through an inlet in the kerb, and is then slowed down by a diffuser flag, and kept at surface level to be absorbed by the soil. This both supports plant life and prevents the water from immediately entering the sewer system.
As well as playing a role in water management, rain gardens are good news for the environment too, as they reduce water pollution. Like permeable paving, they act like mini filtering systems, taking in the water with its pollutants, absorbing it and releasing it freshly cleansed.
Easier installation
Until now, rain gardens have used up valuable resource in the building process as they’ve had to be cut to bespoke measurements. However, Marshalls has developed an off-the-shelf system comprising three simple elements to make it easier than ever to add rain gardens to a project.
Combining a purpose-made left-hand inlet and right-hand inlet with an integrated kerb gradient, the EDENKERB® system encourages water into the rain garden, while a diffuser flag slows its flow. Manufactured as a single modular design, it not only reduces the margin for error but also saves time on installation as you don’t have to design, cut and install it made-to-measure.
A biodiverse water management strategy
As the needs of BNG and Schedule 3 become a practical reality for builders working on multi-plot developments, clever solutions that tick both water management and biodiversity boxes will be critical.
The true beauty of Marshalls’ rain garden kerb is that it makes it easier than ever to integrate rain gardens to building projects, when swift action is required to make longstanding and widespread change to protect our communities from the risk of flooding, while creating biodiverse and beautiful landscapes. This enables builders to leave a positive and lasting legacy – something they’ll be proud to be part of.
For further information on Marshalls rain garden kerb visit Rain Garden Kerbs from Marshalls | Marshalls.
