What will Phase 2 include?
This phase will provide new large diameter floodwater culverts beneath West Street and East Street. The existing surface water pipe will remain in place and repaired where required.
- Works will start south of Lotts Store where the existing brick headwall will be replaced with a new reinforced concrete outfall for the existing 375 mm diameter and a new 1250 mm diameter surface water pipes.
- From Lotts Store to the junction with Green Lane, a new plastic 1250 mm pipe will be installed through the centre of the road at depths down to 3m from the current road level.
How will Phase 2 be built?
Plastic twin walled pipes are being used for the new floodwater culverts.
They are up to 94% lighter in weight than concrete, and easier to handle and transport. They also contain a high proportion of recycled material.
It is anticipated that there will be 32 new manholes. These are needed for inspection and maintenance, and are required at changes of direction and connections.
A screen and catch pit at the north end of the pipe will restrict debris and silt from blocking the culvert.
To reduce the risk of utility works being undertaken after these works, each utility company has been asked to identify: Planned works; Issues with existing infrastructure; and Opportunities to work together to undertake works at the same time.
As the diagram opposite shows, because some of the pipes linking to the existing foul sewer are expected to clash with the new floodwater culvert, a new foul sewer and connections will be provided on one side of the new culvert. This proposal has been agreed with Southern Water.
Properties that need to pump out during flooding will be able to drain into new gulley pots that will connect with the floodwater culvert.
Typical section of the works
As the typical section shows, the new floodwater culvert will be installed deep in the ground to minimise the impact on other utility services. However, some diversions will still be required and connections from properties will need to be cut and reconnected as quickly as possible. All residents will be notified in advance.
Working space will be extremely limited. The work will be undertaken in work zones. Only pedestrian access can be maintained through the work zone and the road in this zone will be closed to all other traffic.