Concerned residents in Suffolk have directed us towards a planning application submitted last month by CEMEX to quarry Lime Kiln Farm, an extension of Wangford Quarry. The site has been proposed by Suffolk County Council as a Preferred Area for gravel extraction in its draft Minerals Local Plan, despite being in the Suffolk Coast and Heaths AONB – where "planning permission should be refused for major development other than in exceptional circumstances" NPPF 172.
Readers will remember Aggregate Industries’ attempts not so long ago to win consent in the East Devon AONB – to process material from Straitgate at their existing plant adjacent to the East Devon Pebblebed Heaths. Approval would have meant a continued blight on Woodbury Common, and would have introduced nitrate-rich agricultural soils into an area sensitive to any nutrient change. After concern from Natural England, AI withdrew its application and has now relocated the plant.
But we’ve digressed. The reason for this post was to contrast the difference between CEMEX and AI in relation to protecting nearby groundwater supplies.
CEMEX has submitted a range of documents in support of its application to extend Wangford Quarry and to quarry up to 1 million tonnes of gravel over some 11 years. The small number of documents submitted by CEMEX contrasts with the huge jumble of fragmented reports AI has been forced to submit in its multi-year quest to win consent to quarry Straitgate Farm – a clear indication of the number of constraints the company faces here in East Devon.
One of the CEMEX documents is a Hydrogeological Assessment – again, a brief affair compared with the tomes supplied by AI’s consultants Amec Foster Wheeler for Straitgate. Interestingly, CEMEX’s consultants rely on "(Brassington, 2007)" – a reference to academic literature by Professor Brassington, a leading authority on groundwater, who recently wrote a damning report concluding that 'ANY quarrying at Straitgate would cause problems'. For the Wangford extension, the salient features are a public water supply 280m away, no private water supplies located within 2km, and a proportion of the site within an Environment Agency Source Protection Zone 2. Groundwater levels have been monitored close to the proposed site since 2002 and show a typical range of 0.6 to 1.4mAOD. In contrast, at Straitgate, which also has a SPZ2 designated across part of the site, groundwater levels have been monitored since 2013 and fluctuate in some areas by no more than 24cm and other areas by as much as 6m.
CEMEX’s report is in stark contrast to the risks AI is prepared to take with the "fragile groundwater system" at Straitgate. The conclusions from CEMEX's consultants, JBA Consulting:
Quarrying involves activities that have the potential to affect the hydrogeological environment of the area. These activities have been identified and an assessment of their potential effects made.
The operational phase potentially poses the greatest risk to the groundwater regime because it will involve constant earthworks and frequent vehicle movements. There will also be minimal vegetation and no soil within the excavation area.
The main potential impacts to the hydrogeological environment are: alteration of recharge pattern, reduction in groundwater quality and increased groundwater vulnerability.
Proposed mitigation measures include the use of a Pollution Prevention Plan and the limitation of all workings to at least 1m above the highest water table.
Yes, that’s right. For this very level Suffolk site, where the maximum groundwater level is relatively easy to model, CEMEX still proposes that working will be limited to "at least 1m above the highest water table". CEMEX's Non-Technical Summary reiterates:
Historically quarrying has always left 1 metre of undisturbed sand and gravel between the bottom of the quarry and the surface of the groundwater. It is proposed to continue to do this when quarrying Lime Kiln Farm. This will, however, reduce the depth of dry, or unsaturated, sand and gravel that lies above the groundwater. In turn, this means that it is easier for potentially polluting liquids, such as fuels and lubricants, to reach and pollute the groundwater if they are spilt. 2.7.4
In contrast, at Straitgate, AI is proposing to leave a 0m unquarried buffer above the maximum water table; a maximum water table the exact position of which is still unknown, and where – as AFW admitted before whitewashing its reports – "there is the possibility for steps in the water table related to faulting" and "there is also likely to be other unmapped local faulting".
The aquifer underlying Straitgate supplies water to more than 100 people, to livestock farms, wetland habitats in ancient woodland, mediaeval fishponds, and a Grade I manor house. Dr Rutter is "concerned that there is a very steep hydraulic gradient across the site... Variations in the shape of the water table cannot be contoured based on the number of piezometers used". Prof Brassington says "an unquarried buffer of at least 3 m [should be] left above the maximum water table to minimise the negative impacts".
The aquifer underlying Straitgate supplies water to more than 100 people, to livestock farms, wetland habitats in ancient woodland, mediaeval fishponds, and a Grade I manor house. Dr Rutter is "concerned that there is a very steep hydraulic gradient across the site... Variations in the shape of the water table cannot be contoured based on the number of piezometers used". Prof Brassington says "an unquarried buffer of at least 3 m [should be] left above the maximum water table to minimise the negative impacts".
If AI doesn't propose to leave an unquarried buffer above the maximum water table to safeguard water supplies – a buffer typically employed by CEMEX, Hanson and others, as we posted in Quarry companies struggle to dig in the right direction, let alone to the nearest cm – what does it propose? AI's cunning plan is to rely on groundwater levels falling by at least 1m over the summer months – and clearly in some areas they don’t – before digging down to the maximum water table, and backfilling with overburden before groundwater levels rebound in the winter. Prof Brassington says it’s "untried anywhere else in the country" and "too difficult for typical machine operators". We’ve posted on the scheme before in No wonder AI wants to keep Straitgate’s groundwater data secret, Seasonal working scheme for Straitgate can't work as AI describes and AI was asked a very simple question.
If that doesn’t ring warning bells, consider that the authors of this "revolutionary" scheme – at AI and consultants AFW – are both no longer with their respective companies.
What if this experiment screws up drinking water supplies and mediaeval fishponds? Who would sort out the mess, given AI’s legal assurances for alternative water supplies are “unfit for purpose”? Let’s hope the EA and DCC have some good answers. They could never say they weren’t warned.
