Source control SUDS secures clean
future for retail-park.
Following a review by the Regulating
Authorities, developers at Cribbs Causeway
Retail Park on the outskirts of Bristol have
turned to Stormwater Management’s
D-Rainclean™ bio-remediation drainage
channel to prevent contaminated surface
water run-off generated by a heavily
trafficked car park from polluting the
nearby River Trym - a delicate ecosystem
which is home to a wide range of
protected fauna.
The initial SUDS proposal for the site,
which has more than 12million visitors a
year, was to use a porous pavement that
would collect and pass run-off through
an oil interceptor before discharging
into the river. With such high volumes
of traffic and the associated potential for
surface contamination, the regulators and
planning authority considered that a more
robust and effective sustainable drainage
solution was needed to minimise any
pollution risk.
“The unique filter media within the
D-Rainclean channel provided the assured
long-term performance the developer
needed to satisfy the regulators,” explains
Neill Robinson-Welsh, Technical Sales
Manager at Stormwater Management Ltd.
“And from the developer’s perspective
the new scheme was equally beneficial.
It was quicker and more cost effective to
install - as it was based on a conventional
impermeable asphalt surface - and no
interceptor was necessary, eliminating the
need for any additional electrical service
connections, alarm systems and expensive
ongoing maintenance.”
In total, 448 metres of D-Rainclean have
been installed within the site catchment.
Run-off enters the porous channel
through a 300mm wide cast iron grating
rated for heavy goods vehicle traffic
(Load Class D400) where it comes into
contact with the filtration media. Passing
under gravity through the filter layers
hydrocarbons and dissolved heavy metals
are removed leaving the clean water to
enter the watercourse indirectly through
ground infiltration or via a perforated,
high strength carrier pipe installed within
a gravel soakaway directly below the
470mm deep channel.
“Independent quality tests on treated runoff from the D-Rainclean system at Cribbs
Causeway have shown that 90% of Total
Suspended Solids (TSS) including below
63microns and over 88% of dissolved
heavy metals had been removed - this
meets the discharge quality required
by the Water Framework Directive and
confirms D-Rainclean to be an extremely
effective remover of priority pollutants,”
says Neill Robinson-Welsh. “The results
also predict that the filter media will
maintain its performance level in this
location for up to twenty years before it
needs replacing.”
Manufactured from robust polypropylene,
each D-Rainclean channel section is
500mm long with an internal baffle wall
at its midpoint which allows the system to
be laid level or to a fall. Bulkheads at each
end ensure dimensional stability and limit
pollution spillages to a confined section of
the system. Eight 100mm diameter holes
in the base of the each section give the
channel its porosity, allowing water to pass
through to ground.
The latest brochure explaining the full benefits and options available for the D-Rainclean bio-remediation infiltration cha