County Hall chiefs are assessing the viability of a flood tank at Knowle that could avoid property damage worth £3.3million.

Devon County Council (DCC) was this week surveying Station Road to extend a topographical study of the parkland – a first step in implementing Sidmouth’s 2014 surface water management plan (SWMP).

The authority has a funding allocation for 2018/19, so it is working to appraise the project and justify the cost – estimated at £436,000 in 2014’s SWMP – before it approaches government department Defra.

Councillor Stuart Hughes said: “One of the recommendations of the Sidmouth SWMP was to consider attenuating surface run-off in the grounds of Knowle. The preferred scheme and design are very much in the early stages, so this additional survey data being collected will assist us in determining the viability of this option.

“If suitable, then we will look to develop the detailed design and project appraisal to secure the required funding from Defra.”

The SWMP, compiled by Jacobs, said that the total predicted damage in Sidmouth town centre could be worth £12million over a 50-year period if surface water flooding is not addressed. Some 14 per cent of homes and 49 per cent of non-residential properties are at risk. It said ‘realistic and sympathetic’ landscaping at Knowle could provide storage for three million litres of floodwater that would otherwise run down Station Road toward the town centre.

The basin would be dry most of the time and would only store water during times of extreme rainfall, allowing the site to remain accessible. It would then be discharged into the drains once the peak of the flood has passed. Water storage at Knowle was among the options put forward for reducing the flood risk – but it would be most effective if combined with other measures. These include re-profiling All Saints Road and Station Road. The SWMP also proposed a pumped drainage system to prevent water ponding in Bedford Square and a ‘quick-win’ scheme to contain Cheese Lane’s watercourse.

It did not consider the risk of flooding from the River Sid or the sea, which remain the responsibility of the Environment Agency.