Page 125 - Oxfordshire SuDS DESIGN & EVALUATION
P. 125
Bioretention features are defined by Recent ideas about planting, including ‘prairie
aggregate filtration below specialist highly planting style’, have influenced both the
permeable soils. This can be a testing choice of plants and the growing mediums
environment for planting and so further used in recent SuDS features.
requirements exist:
These new approaches combine a new Detailed Design
■ Bioretention planting, located in public palette of herbaceous plants and grasses
open space, must be resistant to damage with the free draining soils recommended for
and neglect. Certain evergreen suckering bioretention structures and are being trialled
shrubs and ornamental grasses can resist on green roofs and modified bio retention
occasional damage and require simple features.
maintenance.
Plants chosen to withstand dry conditions of
■ If tree planting, consider fine leaved free-draining soil profiles may be from many
species that do not generate heavy leaf sources.
fall.
In these cases, a deep stone drainage layer
■ Select drought tolerant species. overlain by an open graded growing medium
based on crushed stone with 15 - 20%
■ A regular mulch of coarse organic matter
organic matter and about 10% of loam added
is also important to keep the soil healthy to the mix may be used. This soil layer is then
and the surface of the soil open.
topped by crushed stone.
Road runoff is largely managed by the very
large surface area of very free draining soil 120
rather than a dense planting mix.
Facing: Herbaceous and grass planting used
to dramatic effect at Australia Road SuDS
Park.
Attractive and wildlife friendly herbaceous
planting by Sheffield City Council in a
crushed stone bioretention substrate.
Oxfordshire County Council SuDS D & E Guide © 2018 McCloy Consulting & Robert Bray Associates
