"In a worst case scenario we could lose the River Misbourne forever"

The River Misboune could disappear completely in a worst case scenario
The River Misboune could disappear completely in a worst case scenario

Concerns are mounting over the stability of the Misbourne Aquifer as HS2 preliminary ground work begins.

Chiltern Society Geological adviser Dr Haydon Bailey said that a major regional water supply could be damaged, disrupted and disturbed by HS2 groundworks taking place in the area.

In the worst case scenario, he said "We could lose the River Misbourne completely."

The Misboune Aquifer, which is part of the natural water supply for a large area of the North-West Home Counties could be under threat from drilling into the chalk as the HS2 Contractors begin work on the Chiltern Tunnel.

He said:" The Chilterns Area of outstanding Natural Beauty comprises of a series of chalk stream valleys, including that of the River Misbourne. Within each of Valleys is a fragile hydrogeological ecosystem which we access and use to provide our regular water supplies. We need to treat these systems with care if we wish to maintain this natural aquifer."

The concerns relate to tunnelling near the top of the aquifer, which brings 'risks of diverting water' through a different route.

Water runs naturally through the aquifer, through fractures in the rock. When this gets disturbed water will run through a different route.

Fractures within the chalk provide major water conduits throughout the underground aquifer system. Their precise locations are unpredictable, meaning that tunnelling operations could easily breach the aquifer, potentially causing long term damage that could affect the water system over a long period.

There are concerns that because the tunnel construction will be within the water table, there is a possibility for damage to the aquifer and potential pollution of the water system.

There are further concerns relating to the boring near the Chalfont villages. The tunnelling is at a proposed depth approximately 20 meters, which presents a real and present danger of tunnel collapse, with less than three meters of 'unweathered chalk' existing above the tunnel crown.

Dr Bailey said: "Worst case scenario in all of this, we could lose the River Misbourne Completely.

"HS2 should look at cutting the tunnels deeper into the Lower Chalk which is below the main aquifer to nullify this risk."

A HS2 spokesman denied there was a

We can assure people that there will be no pollution to water as a result of work HS2 is doing to prepare for construction of the Chiltern Tunnel.

“Managing our impact on the environment is a high priority, and we work closely with Affinity Water and the Environment Agency on a series of mitigation measures approved by Parliament.”