Friday, 19 June 2015

One map 'edited out' of AMEC’s flood risk assessment



The Environment Agency expressed concern that Aggregate Industries’ plans for Straitgate could mean:
A possible change in recharge and runoff patterns (e.g. an increase in runoff and decrease in aquifer recharge during high intensity rainfall events ) as a result of removal of part of the unsaturated zone, with the potential to impact on: eastward flowing groundwater; the flow of springs; local private water supplies; the volume of groundwater draining to Cadhay Wood CWS and Cadhay Bog CWS. 7.104
AMEC has prepared a Flood Risk Assessment, and accepts that "the four watercourses which rise from springs and seepages at the margins of the BSPB around the site pose a flood risk to localised areas downstream from the site" 3.4.2. Amazingly, however, the only reference to the extreme flooding of 2008 in AMEC’s report says:
In [DCC’s Strategic Flood Risk Assessment], several significant flooding events in the East Devon Catchment are noted, of special significance to the Site was the flooding that occurred at Ottery St Mary (3km east of the Site) in October 2008; "This resulted in an estimated 350 properties flooding from main rivers, ordinary watercourses and surface water, with 25 people requiring assistance from the fire service. The incident is considered to be the worst flood event to have occurred in Devon in the past 25 years." 2.3.7
No mention of 2008 in Section 3.3 "Historic flooding". Which is odd, because the company was fully aware of the facts in 2013 - here’s AMEC’s report from that time, which included some of our photos and the map above. All traces of the impacts of 2008 have now been edited out. How can a comprehensive flood risk assessment ignore such an important event? After all, it was in 2008 that the Cadhay Bog watercourse flooded 50 properties at Thorne Farm Way, prompting the EA to build a flood defence scheme there.

Editing out this flooding event surely undermines the whole integrity of AMEC's Flood Risk Assessment.

But whilst AMEC and SLR happily write-off the flood risk to local people, tellingly, it warns AI workers:
Access points to the quarry should be clear of the four watercourses near the Site so that safe access and egress can be maintained during extreme rainfall. 5.1.1 A formal Site evacuation/risk management plan should be drawn up and staff briefed with regards to procedures if flooding affects parts of the quarry or one or all quarry access/exit routes. 5.1.2
The EA map shows all four watercourses from the site have a high risk of causing surface water flooding:



AMEC says that surface water runoff during any quarrying would be captured by "infiltration ponds... supported by the construction of an impermeable bund", such that "23% of working areas [would] be reserved for infiltration... 6.2 ha [15.3 acres] of infiltration area is required for every 26.4 ha of working area" 4.1.14. It’s anybody's guess what would happen after quarry operations have ceased, when the impermeable bunds and unsaturated sponge-like sand and gravel layer have gone, because "arrangements for the collection and disposal of surface water arising from the restored site" have not even been designed. 3.57

Here are photos of the damage that flooding immediately downstream of the site can do, in 2008 and in 2012; the two on the left appeared in AMEC's first report, but, unsurprisingly, not the report that supports AI's planning application. 




The EnviroCheck maps are copyright © 2012 Landmark Information Group drawing from sources which themselves are protected under Crown Copyright (Ordnance Survey, Environment Agency, British Geological Survey, and other public authorities) or under copyrights owned by private enterprises. You are kindly requested to use these maps solely for activities relating to the Straitgate Action Group, as other uses may not fall under the licence granted.