SUDS POLLUTION DEGRADATION
Environment Agency of England & Wales
Scottish Environment Protection Agency
Department of the Environment Northern Ireland
Background to the Research
SNIFFER Project UEUW01 SOURCE
CONTROL OF POLLUTION published in February 2008 included
field monitoring and artificial dosing experiments. It demonstrated the
effectiveness of various SUDS techniques in attenuating and degrading a
range of diffuse source pollutants arising from motor vehicles. The
project established an evidence base to aid future policy development
in this area.
Two aspects of the work could not be finalized by February 2008 and it
was decided to continue with these and, since additional work was being
undertaken, a third aspect was undertaken. All three aspects
are reported in this supplementary report.
Objectives of the Research
The three aspects reported in this supplementary report form the
objectives which were;
Key Findings and
- To continue
the degradation study. Samples had been stored
and it was decided to analyse the soil samples after a further period
of approximately six months of degradation.
- To integrate
results from two research programmes. A separately funded
research programme was carried out in parallel with the work undertaken
for report UEU01 but was not reported there. This report
includes a preliminary integration of the research outputs of both
- To develop a
risk assessment flowchart. A speculative design flowchart
was included in the first draft of the final report of
UEUW01. It was considered that some further work developing
this flowchart was merited.
It is concluded that it is better to control oils and Poly Aromatic
Hydrocarbons (PAHs) in soil based SUDS at locations which are
periodically wet and dry such as in the base of detention basins,
swales or infiltration basins. Basins and swales are good for
sediment removal and, by association, oils and PAHs will also be best
removed there and not in ponds or wetlands.
This research supports guidance that a soil based system should be used
as the primary control of sediments, with the pond or wetland as a
polishing component where required.
For the traffic loadings in this study, the degree of contamination
found suggests road traffic is a significant source of oil, but SUDS
are effectively trapping them, protecting the receiving water
Waste arisings from SUDS serving busy highways will most probably have
to be treated as contaminated waste and reduced and recycled.
However, the amount of waste which might arise can certainly be
minimised using the results of this research.
Results from this study suggest that source control measures such as
grass filter strips, swales, and detention areas, should be priority
features of sustainable drainage networks serving urbanised areas and
highways, where oil contamination may be significant. This is
entirely consistent with the treatment train and stormwater management
concepts for sustainable drainage systems.
Information to assist in preparing a design flowchart to meet the
environmental and other risks posed by pollutants from highways has
been considered in this report. A diagram has been included
which shows the type of research/ studies required to develop this
Recommendations for Uptake
The results will be best used to inform the ongoing improvements to the
Design Manual for Roads and Bridges. This work will be taken
forward by the Highways Agency.
Sustainable Urban Drainage Systems, SUDS, Groundwater Protection,
Pollutant Breakdown, PAH Studies
Copies of this report are available from the Foundation, in electronic
format on CDRom at £20.00 + VAT or hard copy at
£15.00, less 20% to FWR members.
The report is available for download from the SNIFFER Website