Photographs of Canada Geese at Aggregate Industries’ nearby Blackhill Quarry on the aptly named Seagull Pond can be found at the top and bottom of this post.
Canada geese are one of the more dangerous bird species for aircraft to strike because of their large size and because they travel in flocks of up to several hundred birds.
In 2017, in response to Aggregate Industries’ application to quarry Straitgate, Exeter Airport wrote:
Exeter Airport have no safeguarding objections to this development providing that the... conditions are adhered to at all times and there are no changes made to the current application.
One of those conditions was:
No new permanent bodies of water should be allowed on the site without prior consultation.
Permanent bodies of water like Aggregate Industries left after quarrying nearby Thorn Trees Plantation:
Permanent bodies of water like Aggregate Industries left after quarrying nearby Venn Ottery – as shown in the Council's latest monitoring report:
Earlier this year, Exeter Airport wrote:
Exeter Airport have no safeguarding objections to this development provided there are no changes made to the current application and that the previously submitted Wildlife Hazard Management plan is adhered to at all times.
On the proposed infiltration areas to contain flooding, the WHMP says:
The primary purpose of ditches is to prevent flooding. These ditches reduce the amount of water ponding, therefore reducing the amount of food and habitat available to wildlife. They are critical in reducing the duration that critical areas are inundated for. This in turn reduces the amount of seasonal habitat for water birds and waders.
The problem is, there have been changes made to the current application, such that these drainage ditches or infiltration areas cannot work. Surface water runoff would not infiltrate evenly along the eastern boundary, given the revised gradient of the proposed extraction base, but would instead collect in the low areas. The ditches could not be accommodated where specified without breaching the maximum water table. Furthermore, the Environment Agency's drainage condition that "the working and restoration infiltration design shall ensure that drainage mimics the pre-excavation drainage" cannot be satisfied, given that the base of any quarry, the revised MWWT – the contours which would define, in perpetuity, a large part of the restored landform – do not mimic the existing topography.
The Flood Risk Team has objected on the basis that "the applicant has not submitted sufficient information in order to demonstrate that all aspects of the surface water drainage management plan have been considered."
Exeter Airport will be unaware of all of this. Exeter Airport will also be unaware that Aggregate Industries has, according to Professor Brassington, exaggerated the infiltration rates used in the design of these drainage ditches. The Flood Risk Assessment – which is now more than four years old and has not been informed by the elevated groundwater levels recorded, or the revised MWWT contours – has assumed unrealistic infiltration rates. Appendix C 2.2 says:
Infiltration rates of 1m/d (0.0416 m/hr) were applied to the infiltration ditches/ponds...
The soakaway tests carried out did not allow an infiltration rate to be determined using the BRE approach although the fall in water levels suggested a permeability in the order of 0.60 to 0.90 m/d. In my opinion, these results cannot be reliable because the loosely replaced broken-up material in the trial pit will not have been trafficked by heavy machinery in the same way that the proposed replaced layer would be. In any event, the tests were hardly conclusive as the comment was made ‘Insufficient drop in water level. Unable to calculate infiltration rate’. This does not suggest a permeability as high as 0.60 to 0.90 m/d, indeed, it could easily be in the range 0.06 – 0.09 m/d or even lower.
A lower infiltration rate will obviously affect the capacity that must be set aside to contain surface runoff.
Exeter Airport has been consulted on unworkable, exaggerated, out-of-date information.
