Polypipe,
the UK’s leading manufacturer of sustainable drainage and water management
systems, has supplied a complete attenuation solution for the £1.3 million
Kidderminster Linnet Rise Flood Alleviation Scheme.
The lack
of capacity in the area’s existing highway drainage network placed many
properties on the residential area of Linnet Rise at risk of flooding, with the
consequences most recently seen in 2007, when thousands of pounds’ worth of
damage was caused by a flood, following torrential rain.
The
scheme was designed to ensure a collaborative approach to solving the area’s
flooding issues by providing a SuDS system that would provide long term defence
with minimal intrusion to the existing space.
Polypipe
was approached due to its extensive track record of successfully delivering
attenuation systems for developers and contractors.
Working
closely with contractor NMCNomenca and Severn Trent Water, Polypipe supplied a
complete prefabricated solution using Polystorm geocellular tanks, together
with pipework, manholes and catchpits all manufactured off site.
The
solution would also allow the installers to negotiate the very tight parameters
of the Linnet Rise site, where space to maneuver plant equipment would be a
challenge.
The
solution delivered by Polypipe and NMCNomenca retrospectively addressed the
site’s drainage issues for the long term, while keeping installation time and
disruption to a minimum, showcasing the capabilities that Polypipe can offer
when improving the standards of flood protection in heavily populated areas.
Polypipe’s system was also fully adopted by Severn Trent Water.
The
final design saw the installation of two Polystorm geocellular tanks at a depth
of 3.2 metres, under two resident owned car parks on the Linnet Rise site,
providing 366m3 and 479m3 of storage respectively. The tanks were
formed using Polystorm cells, which boast a 95% void fill ratio. This solution
maximised the tanks’ storage volume within the limited space available for an
attenuation system on this compact housing estate. These tanks will safely
store flood water in the event of surface water sewers reaching capacity
following heavy downpours, before releasing water back into Severn Trent’s
watercourse once the downpour has subsided.
The two
tanks were laid at a 1 in 150 gradient across both length and width, to
facilitate draindown to the primary inlet and outlet located in the bottom
corner of the crates. This will ensure that any sediment entering the tank from
the surface water sewer is flushed out through the same flow path. Three
channels were also installed in each tank, to promote water flow dispersal
throughout the geocellular crates and provide inspection points along the
length of the tanks, which are accessible via six specialist access turrets
located outside of the site’s car parking bays.
Polypipe’s
gravity return design means that the two tanks fill and empty without using any
pumps or valves and therefore, following installation, the system will cost
nothing to run and require minimal future maintenance by Severn Trent Water.
Polypipe’s
ability to design and manufacture pipework, manholes and catch pits off site
provided the perfect solution to the project’s limited working space and the
need for quick installation. The supply of high quality parts, designed to the
project’s exact specification and delivered directly to site, meant that the
system could be installed in a single day, reducing both contractor costs and
disruption for local residents.
Rosie
Cheetham, Marketing Consultant at Polypipe, said, “This project highlights the
capabilities that our SuDS water management systems can deliver in improving
the quality of life for residents in urbanised areas. Forming a vital part of
this retrofitted alleviation scheme for Linnet Rise, our tailored solution
countered the limitations of the original drainage system to offer long lasting
flood protection. It also ensured that the installation process caused as
little disruption to residents as possible, thanks to our ability to
prefabricate components ready for quick and easy installation on site. The
success of the Linnet Rise project is an excellent example of how our
innovative water management systems can make retrospective flood protection possible
even in densely populated urbanised areas.”
