SuDS in London - a guide

2.11 Working with
London’s utilities
Footway and carriageway space in London
is limited and often highly congested
below ground with utilities that supply
London’s gas electricity, water, sewerage
and telecommunications. Much of this
infrastructure, which was installed in the
late 19th and early to mid 20th centuries
is ageing, poorly documented and
maintained, although its exact location is
often difficult to pinpoint.
SuDS designers should work closely with
utility providers because utilities can be
expensive and disruptive to divert. During
feasibility and option appraisal stages
of SuDS design, the team should apply
to each utility owner for information on
their assets or associated assets. This
information should be validated.
During feasibility studies and option
appraisal stages of design, it is
recommended that high quality surveys
are obtained to identify services and
avoid abortive works later in the project.
Underground assets should be recorded
and this information given to the relevant
highway authority or landowner.
Below ground infrastructure
Contaminated soil
2.12 Contamination
In London, contaminated soil and
groundwater is likely to be found when
installing SuDS components because
there are few places that have never been
subjected to some form of development or
industrial activity. However, contamination
should not preclude SuDS. Early in the
process, a specialist should be appointed
to identify contamination risks and sources
so an integrated remediation strategy can
be explored. Designers should consider:
• The risk of mobilising contamination
through increased infiltration
• Risk of contamination entering SuDS
features and contaminating relatively
clean rainwater runoff; this could have
adverse effects on vegetation and
materials used within SuDS components
• Excavation and disposal of contaminated
soils is likely to be expensive
• SuDS should not compromise
remediation systems in place to protect
users from the contamination
Further information:
CIRIA C753 The SuDS Manual, Chapter 26
26 2 The London context