Flood Mitigation Scheme

The floods of 2000 and 2014 are a still a painful memory for many in the village.

In addition to these two occasions, flooding has nearly occurred in several other years.

The flooding causes  disruption to  village life and damage to homes, businesses and the Parish Hall, to the doctors and their patients and to the Pharmacy.  Hazeley Road becomes flooded, the car park becomes unusable and the flood water overwhelmed the foul sewer drains meaning many homes had blocked and backed up toilets.

Climate Change makes these flood events even more likely.

In the 2014 floods, 19 residential properties were impacted by flooding (internal, cellar, and external flooding), 15 properties lost the use of the sewer system, and 2 further properties (Parish Hall and Post Office) experienced internal flooding. The flooding started in mid January 2014 and continued for around six weeks.

Questions and Clarifications

If you have a question which isn’t answered below then please do fill out the Contact Form and we’ll do our best to get an answer to you as soon as possible.

Previous Work & Reports

An Environment Agency report provides the background to  the flood of 2000/01. Following this  Hampshire County Council (HCC) restored the large drain from the  Post Office traffic lights junction  to Churchfields; this coped with the flood of 2014, but HCC did nothing to the drains upstream of the traffic lights, along Hazeley Road,  with the result that the flood of 2014 repeated the damage of 2000/01.  HCC produced a report on 2017 and options for mitigation

Central Government cuts have prevented HCC from  carrying out the necessary work since then. The Parish Council  stepped into this vacuum and asked if it could take the scheme and pay for it; HCC agreed.

The Current Scheme

The aim is to restore adequate capacity for the Bourne when it rises in winter and then flows for several weeks. This capacity used to exist as a ditch until the 1960’s when Hazeley Road was widened. The ditch was put into a pipe which was much too small for the Bourne in flood conditions  so the ditch overflows and pours into  Hazeley Road.

The scheme is to take out the small pipe  and replace it with a ditch, extending the ditch  which runs along side the footway from Bourne lane. This is 90 metres in length, with part of the existing ditch also being widened and new headwalls installed. There will be a culverted crossing point for Twyford School so that they can continue to use their access to and from the playing field.

The total scheme is around 120 metres in length, it then connects into work being carried out by the developer in front of their site.

It should be noted, that this is a Flood Mitigation Scheme and there is no 100% guarantee that it will prevent all future flooding scenarios. The system would still be constricted by the 450mm diameter pipe downstream from the ditch works. Therefore, even though the ditch capacity will be increased by a factor of 4, during the most significant events it is possible that  some water will still overtop the ditch and flow into the highway.

In 2018 the Parish Council commissioned Consultancy Engineers, Mayer Brown, to assess the current drainage infrastructure produce a report and a detailed design for a scheme to tackle the issues along Hazeley Road. Their report was first published in 2019 with a final report completed in 2020 and this formed the basis to take forward a credible proposal.

The work is being tackled by different bodies. HCC have repaired their existing drain; Alfred Homes Ltd will deal with the pipe work across the frontage of the development site, leaving the works up stream to the Parish Council.

The Council applied for grants towards the work and was successful, after several attempts, to secure funding from Winchester City Council and the South Downs National Park Authority

In 2024 Council appointed Consulting Engineers to create drawings that the scheme can be constructed to. These drawings  have been approved by HCC under the Land Drainage Act 1991.

HCC will adopt the scheme following its construction and be responsible for its maintenance.

On the entrances to the two culverts in the scheme there will be trash screens. These prevent debris from entering the culverts and blocking them:

The Contractor

The building of the 22 houses by Alfred Homes provides the opportunity to undertake the Parish Council’s  works as part of the larger project.  This is more efficient for the Council from a cost perspective but also from a community perspective because it means the flood scheme works, along with the housing construction site work and traffic management is fully coordinated by Alfred Homes. The Council sought the opinion of a Quantity Surveyor before awarding the flood scheme construction contract to Alfred Homes to ensure the costs were appropriate.

Trees & Hedges

The ditch is well below the level of the  road, so , for this 90m length,  the trees and the hedge  will be  removed.  There are 7 trees that will need to be removed.  These were planted by a group of parishioners about 30 years ago but unfortunately  directly on top of the of the inadequate pipe.

During an ecological survey it was confirmed that there are no protected species such as dormice using the hedge.

The hedge will be replanted after the works have been completed. The replanting of the trees will have to be agreed with Hampshire County Council once the construction work has been completed and a suitable space identified.

How much is this costing?

The cost of the construction contract, including the design works is expected to be £87,000.  The Parish Council was successful in grant applications to Winchester City Council and the South Downs National Park Authority to cover this cost.

The Quantity Surveyor appointed by the Parish Council to review cost and design and provide an opinion was £4,385. This has been met from Parish Council resources.

The earlier Mayer Brown reports and surveys cost £21.8k.  £10k of this was funded by Hampshire County Council with the remainder being provided by the Parish Council

When will the work start and how long will it take?

The work is scheduled to commence in January 2026. The hedge planting will take place after the construction phase is completed.

Other Information 

The  ditch replacement  takes place on land which the then owner David Wickham has made available; it is now owned by Twyford School whose cooperation is also recognised.

Questions and Clarifications

If you have a question which isn’t answered above then please do fill out the Contact Form and we’ll do our best to get an answer to you as soon as possible.