Ottery St Mary has a long history of flood events. Straitgate Farm sits on a hill above the town; four watercourses emanate from it. Removing a million tonnes of sand and gravel from this hilltop site is bound to affect the hydrology and surrounding flood risk. Local people have warned DCC, and so have we; click on the flooding label.
In removing a proportion of the unsaturated zone including the soil layer there will be a reduction in the storage capacity/buffering and so recharge may move more quickly through the unsaturated zone. The extent to which this makes the groundwater hydrograph more "flashier" would be difficult to quantify with a high degree of certainty… Within the proposed development the establishment of a 1m freeboard over and above the highest known water level provides for this eventuality. 3
Unfortunately, and as we wrote last year:
AI’s unorthodox seasonal working scheme does NOT propose to leave "a 1m freeboard over and above the highest known water level". Obviously we can now assume, by inference, that a flashier groundwater hydrograph has NOT been provided for.
Homeowners in the South West are being warned that intense bouts of flooding are set to become more frequent. The Environment Agency launched a Flood Action Campaign last week. EA chief executive Sir James Bevan warned:
Climate change is likely to mean more frequent and intense flooding.
Floods destroy – lives, livelihoods, and property. Our flood defences reduce the risk of flooding, and our flood warnings help keep communities safe when it threatens.
But we can never entirely eliminate the risk of flooding. Checking your flood risk is the first step to protecting yourself, your loved ones and your home.
DCC advised last week that funding is still available to improve a community’s flood resilience.
Last year, DCC, in its role as Lead Local Flood Authority, still objected to AI’s scheme at Straitgate Farm - despite the company having had many years to get its water act together:
At this stage, we object to this planning application because we do not believe that it satisfactorily conforms to Policy MP24 (Flooding) of Devon County Council's Minerals Plan (2011-2031) which states that proposals for mineral development must not lead to an increased risk of fluvial, surface water or groundwater flooding. The applicant will therefore be required to submit additional information in order to demonstrate that all aspects of the proposed surface water drainage management system have been considered.
Any catchment is at risk of flooding associated with a rare, high-magnitude event, whether a natural catchment, or a designed drainage system. These rare events exceed local infiltration/storage capacities and result in concentrated downslope runoff. The proposed infiltration areas at the Straitgate Quarry [sic] have been designed to meet national guidance on design events (1 in 100 year with climate change). However, any bunds that may act to retain water also need to be safely designed to safely pass forward flows from these rare, high-magnitude events as would happen if the rare high-magnitude event occurred over the baseline catchment. 2.18.5
Is this enough? The EA's warning last week:
...follows a pattern of severe flooding over the past 10 years linked to an increase in extreme weather events as the country’s climate changes. Met Office records show that since 1910 there have been 17 record breaking rainfall months or seasons – with 9 of them since 2000.
The threat of flooding is real and increasing – as is also demonstrated by its listing as one of the nation’s major threats.
Last year, the Met Office published new innovative research which found that for England and Wales there is a 1 in 3 chance of a new monthly rainfall record in at least one region each winter.
