Chapter 9: Road drainage and the water environment

Table 9: Summary of proposed works to culverts ( Contractors Proposal for
Drainage, 2009)
From Table 9 above it can be seen that 6 of the 7 culverts will require
modifications. Culvert C/5 will be replaced with a smaller (existing = 1200mm
diameter, proposed = 900mm diameter) culvert since this will be conveying land
drainage only and not highway runoff as was the case for the existing
configuration.
The design team plan to perform a survey on the drainage system. It is
recommended that this includes a visual assessment of the culverts described
above to identify any issues and mitigate against them.
The complete drainage proposal therefore provides an acceptable
mitigation against increasing flood risk.
5.5 Mitigation of Flood Risks from Infrastructure Failure
The level of risk as a result of infrastructure failure is considered to be low.
However, it is suggested that more details of the assets shown on the Severn
Trent service layouts are obtained. Further ground investigation/trial pits may be
required to identify the nature and location of Severn Trent’s assets which conflict
with the location of the proposed scheme. Diversion of Severn Trent’s assets
may be required.
5.6 Incidental Mitigation Measures
Due to environmental concerns the river banks of the Avon will be widened to
create habitat for otters. The extents of the widening has is not confirmed at this
stage of the project. The effect of the river widening, though not the purpose, will
be to increase the conveyance and storage capacity of the river channel, in turn
lowering flood levels and flood risk.
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