SuDS in London - a guide

5.7 Rectory Gardens
Location
Hornsey
London Borough of Haringey
Extent
1,000m²
Cost
£80,000
Date
2016
Credits
Haringey Council
Robert Bray Associates
Thames21
Hugh Pearl (Land Drainage) Ltd
SuDS components
Retention basins
Detention basins
Planted channels
Plan
Summary
Retrofit and transform green space to
manage road runoff.
Project description
Runoff flows directly to the River Moselle
via a surface water sewer connection.
An existing local park was identified for
accommodating SuDS components that
enhanced amenity and biodiversity value.
Objectives
The project aims to collect all the runoff
from a defined road catchment and show
how the full SuDS aspiration of ‘managing
quality and quantity aspects of runoff
while delivering amenity and biodiversity
benefits’ can be met in an existing urban
park setting.
Actions and results
• Runoff from the road is collected in
three bespoke, cast iron inlets that
replace gully pots and perform like chute
gullies, delivering the dirty surface water
into two SuDS management drains
• System A to the west, delivers runoff
to a silt interception forebay basin
• In System B, runoff travels along a
grass channel, which is planted so
oils and silts are concealed but is
easily accessible to remove solids
• The ‘source control’ features are
followed by wildflower meadow
basins that can hold significant
amounts of reasonably clean runoff
to the one in 10 year return period
• An under-drain below the basins
allows water to leave the site at a
greenfield rate. This flow is governed by
a protected orifice control chamber.
• In larger storms, up to the one in 100 year
return period, with a 30% allowance for
climate change, these basins overflow
into further grass storage basins. The
second basins are managed as amenity
grass so are accessible most of the time
• The wildflower meadow basins
have balance beams so that even
when wet or filled with water they
can be used for adventure play
Benefits
89 5 Case studies