Berewood Phase I, Hampshire

Flood Prevention

SDS integrates SuDS into a new residential community.

Overview

The 500 acre “Newlands” residential development at Berewood, Hampshire, is the largest of its type in the UK and, once completed, will accommodate over 2,500 homes, supported by a range of amenities and around 100,000m² of employment land.

Commissioned by Grainger plc and Hampshire County Council, Berewood is a mixed-use development. Our brief was to integrate best-in-class, below ground hard-engineered Sustainable Urban Drainage Systems with above ground vegetative SuDS amenities.

Construction of the development began in 2012 and is scheduled to continue until 2021. The project’s main objective is to minimise the site’s impact on its natural surroundings and deliver ecological benefit to the locality, providing both pollution and flood prevention services while creating a new wetland resource of substantial ecological and amenity value.

What we did

SDS worked closely with Consulting Engineers, Mayer Brown, to establish the key design criteria for the site’s sustainable drainage systems. This resulted in the adoption of a “SuDS management train” approach, whereby a series of drainage techniques are used to change the flow and quality characteristics of the runoff in stages.

Surface water runoff from the roads and the housing development construction site is first cleaned through ditches and swales, before entering SDS’s purpose-built attenuation tanks, along with the water received from numerous water features.

What we did

Phases of consented land are released to housebuilders only after the supporting infrastructure has been installed, for which SuDS are considered a priority. As each phase is launched, further SuDS are installed, with developers integrating the existing surface water drainage scheme into each of the housing and commercial packages.

As part of the project, three tank systems, with a combined capacity of 4,800m³, have been installed to support the infrastructure of the site.

Results

To accommodate the unique complexities of the site that are associated with a clay dominated soil, including a very high water table, SDS has designed and engineered a pioneering method of installation.

As specified by SDS, the hard-engineered features of the scheme are capable of performing their role of controlling water quality and volume, not only upon final completion of the development, but also during its 10-year period of construction.

This is before the natural SuDS elements can be fully established, and with a substantially higher level of water-bound contaminants than might normally be expected. Water leaving the SuDS system has been test proven to be of a higher quality than the contents of the watercourse into which it was being discharged.

By master-planning and installing necessary infrastructure at the very beginning, we have future-proofed our community at Berewood, making it more resilient to the horrid weather we have seen recently. The result is that in spite of the worst rainfall for 150 years the land at Berewood has never looked drier.

– John Beresford, Development Director, Grainger plc

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