Wendover Flooding Survey

We would welcome your feedback about the impact of HS2 works affecting water that flows from the Coombe Hill aquifer, which if not addressed could cause flooding in the Aylesbury area.

The Coombe Hill aquifer is an underground reservoir that gives rise to springs in the Wendover area, which provide fresh water to the Wendover Arm of the Grand Union Canal, the Weston Turville Reservoir Site of Special Scientific Interest (SSSI), and feeds a number of wells serving houses in Ellesborough Road.

When the alignment of the HS2 railway was made public, it became clear that an 80m wide, 3km cutting would be made between Bacombe Lane and Nash Lee Lane (parallel to the A413 Wendover bypass) to enable the Wendover Green Tunnel to be built using “cut and cover” techniques.

Evidence presented to the House of Commons and House of Lords Select Committees in 2015 showed that the cutting would intercept the aquifer, and that the groundwater would be diverted into Stokes Brook rather than emerge in the local springs. This watercourse runs west of Stoke Mandeville at Marsh Lane and then onwards past Fairford Leys to feed into the River Thame.

Since then more extensive groundwater monitoring has been undertaken to determine the scale of the issue, and this supports the Consultant Hydrogeologist’s view presented by Wendover Parish Council that it is highly likely that up to 90% of the aquifer water flow will be diverted and the volume of water affected could be 30 million litres (10 Olympic Swimming Pools) a day on average over the year.

If no mitigation is provided, this could cause repeats of the significant flooding that happened at the Willows estate in South Aylesbury during 2014; destroy the rare wetland habitat at Weston Turville Reservoir SSSI and substantially reduce the water supply into the Wendover Arm and the Grand Union Canal.

The Department of Transport answered recent Parliamentary Questions from our new MP Rob Butler, stating that the detailed design will be undertaken by Eiffage Kier (EK), HS2’s Design and Build contractor following “Notice to Proceed”, which is expected in the next few months. However EK have not yet started the testing that is needed to inform the actual design work and the designs presented so far show no attempt at mitigating the impacts Wendover’s Consultant Hydrogeologist predicts.

The Environment Agency should review the design to ensure it meets the undertakings that HS2 are required to follow, in that existing flows should be maintained at an appropriate water quality, both during the construction works and thereafter once the line is operational, as far as possible. The new Buckinghamshire Authority will be responsible for reviewing wider aspects of the design affecting our local environment. There is no certainty that either have the resources to do this in the limited time scales that the HS2 act prescribe.

With the volume of water expected, a possible scenario is that several additional hectares of agricultural land in the Nash Lee area will need to be compulsorily purchased to form settlement ponds. Pipelines would be needed to allow clean water to be pumped to Weston Turville and the Canal. This would be a significant contract extension, which we know from the recent Oakervee report would be entirely funded from the public purse.

An alternative solution is to avoid the problem, by mining the Wendover Tunnel underneath the aquifer. The vertical alignment would also extend the tunnel south to Rocky Lane, and so:

• Avoid the visual impact of the Small Dean Embankment and Small Dean Viaduct in the Chilterns Area of Outstanding Natural Beauty (AONB).
• Remove the extensive noise nuisance from trains in the Wendover area with a portal only 300m further north than is currently planned,
• Avoid new traffic restrictions being imposed on the A413 London Road, and handle future traffic demands from more Aylesbury commuters.
• Save over £320 million compared to the current designs for the Green Tunnel and Small Dean Viaduct and Embankment.
• Avoid the new costs of the settlement ponds and pipelines.

We are seeking feedback about these issues to enable us to provide a representative opinion to the authorities, and invite you to submit your views on this questionnaire

1. Are you concerned about diversion of water from the Weston Turville Reservoir or the Wendover Arm/Grand Union canal?	No Possibly Maybe Probably Yes
2. Are you concerned about new potential flooding risks from HS2?	No Possibly Maybe Probably Yes
3. Should HS2 be made to redesign the line now to minimise the damage to the Aquifer?	No Possibly Maybe Probably Yes
4. Should the contractors delay starting work before detailed assessment of the flood risk has been undertaken?	No Possibly Maybe Probably Yes
5. Should the Council delay planning approval until a detailed assessment of the flood risk has been undertaken?	No Possibly Maybe Probably Yes
6. Should further agricultural land be compulsorily purchased to create new flood defences near Stoke Mandeville?	No Possibly Maybe Probably Yes
7. Do you think your house is at risk of flooding from HS2?	No Yes
8. Any other comments?
Your name.
What is your address?
Postcode. Please use capital letters.
Email address.
Are you on the Aylesbury Electoral Register?	No Yes
Are you happy for WendoverHS2 to share your details with 3rd parties specifically involved in the assessment of the Flood risk?	No Yes
Would you like to receive email updates from Wendover HS2 about the Flood risk?	No Yes

 

By submitting this response, you are agreeing that your data will be held in a database managed by WendoverHS2.

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