AI’s restoration plan for Straitgate doesn't make sense either

Does any part of Aggregate Industries' planning application to quarry Straitgate Farm make sense? Even the restoration plan has problems.

The company claims "the restored landform will be designed so that drainage reasonably mimics the current condition": 

5.3.3 The excavation is designed to include areas of infiltration that will be sized to capture all runoff from the workings and infiltration areas will be incorporated into the final restoration design. This will be designed to enhance groundwater recharge and will increase infiltration and spring flows by the amount of overland flow that would otherwise have occurred. 

In 2013, the Environment Agency delineated a Source Protection Zone in an effort to protect Cadhay's water supplies. The above plan overlays the SPZ and maximum water table contours – the base of any quarry – over the restoration plan. 

In 2017, in its Regulation 22 request, the Council requested information on the infiltration areas: 

3.6 The MPA has insufficient information about the management of the infiltration/ephemeral pond area to determine whether it will contribute to the appropriate management of surface and groundwater flows; stream recharging; airport safeguarding and long term agricultural restoration.

Aggregate Industries answered: 

Two proposed ephemeral water bodies in the low-lying infiltration areas are shown as part of the Straitgate Farm restoration scheme on Drawing SF/6 (Rev.A). The proposed restoration scheme ensures that post-extraction the site will be returned to a similar baseline condition. The proposed enhanced infiltration areas for the Birdcage and Cadhay Wood sub-catchments are not SuDS and as they are infiltration areas they will not be permanent waterbodies. They are simply a feature incorporated into the restored landscape to assist in providing some betterment over the baseline conditions. These will be formed to enhance the capture of ‘overland flow’ and to locally increase the proportion of rainfall that passes to groundwater. 

But if the restored landform is to mimic current drainage, why on earth is one of these enhanced infiltration areas – areas designed to "to locally increase the proportion of rainfall that passes to groundwater" – located outside of the area that feeds Cadhay’s spring, drawing water away from a crucial water source for a Grade I listed house?

Prof warns DCC – quarry at Straitgate would ‘irreversibly damage’ water sources

Unsaturated zone flow times of 8 YEARS – not the 1 to 3 days consultants claimed...

Drinking water sources suffering PERMANENT acidity increases – due to the LOSS OF 7 YEARS of rock/water interaction times, a 50% CUT...

Piezometers recording lower groundwater levels than reality – enabling extraction DEEPER THAN THE MAXIMUM WATER TABLE...

These are some of the damning conclusions from a new report by Professor Rick Brassington in response to Aggregate Industries’ planning application to quarry Straitgate Farm.

Prof Brassington wrote his new report specifically for Devon County Council – "to ensure that they have a clear view" – given that the Environment Agency "will not be providing further responses", and given the EA's request that "further concerns... should be directed to Devon County Council". The report landed with DCC at the start of this week, but despite Prof Brassington's request, the Council batted the report straight off to the EA, presumably without a second glance, and responded:

If your report raises any new issues which the EA consider to be material then I will ask the applicant to clarify.

However, clearly the report does raise new material issues, which will need much more than clarification to sort out. This would have become immediately apparent if the Council had bothered to read it.

Because, what’s abundantly clear from Prof Brassington’s report is that Aggregate Industries’ so-called hydrogeology experts – Amec Foster Wheeler now Wood – have not been very expert at all. They have either been guilty of intentionally misleading, or have completely misunderstood groundwater behaviour at Straitgate, such as the length of time water takes to permeate down to the aquifer. Either intentionally or otherwise, they have dismissed the role that the unsaturated zone – the resource above the water table that Aggregate Industries wants to quarry – plays in determining the groundwater chemistry.

Prof Brassington warns:

the application for the proposed quarry should be refused because of the irreversible damage that it will cause to the local groundwater system that both supports local habitats and forms the water supplies for Cadhay House with its medieval fishponds and tearooms, more than 100 people plus three livestock farms. 80

By the way, Prof Brassington is not just any expert on hydrogeology; that's obvious from his CV which stretches across pages 32 to 40 of the new report. He clearly has more experience, knowledge and independence than any consultants engaged by Aggregate Industries, a company hell-bent on extracting as much material as possible. He is a recognised authority on hydrogeology, recent winner of the Whitaker Medal, and author of various textbooks on the subject.

Prof Brassington says his new report "should be read in conjunction with the conclusions and recommendations reached in my earlier reports" on Aggregate Industries’ planning application. We posted about these in: Professor of Hydrogeology says ‘ANY quarrying at Straitgate would cause problems’, Professor rebuts EA’s response to his report. Has the EA got it all wrong?, and Another damning response from Professor of Hydrogeology on AI’s Straitgate plans.

This time, Prof Brassington focuses on the permanent change to groundwater chemistry that would result if all but 1m of the unsaturated zone were removed.

Last year, the company’s consultants Wood tried to claim – although clearly they weren’t too sure – that a reduced unsaturated zone thickness would "not necessarily" make any difference:

The moderately low pH, alkalinity and dissolved solids in groundwater in this area is, therefore, not necessarily a function of the time it takes for water to pass through the unsaturated zone, but a function of the variable and limited presence of soluble material within the sub-surface materials. A reduction of the unsaturated zone therefore will not necessarily give rise to a reduction in the pH, alkalinity or dissolved solids concentration of groundwater. With respect to the topsoil, subsoil and overburden that will be replaced once extraction of an area is completed, the replaced material will then be subject to water/rock interaction processes as water percolates through the replaced unsaturated zone material. As is shown by the leach test data, the soluble content of the unsaturated zone is low across much of the site or is mostly influenced by the shallow deposits which will be replaced after mineral extraction. Therefore, again, this implies that removal of the deeper unsaturated material will not necessarily result in a noticeable change in groundwater quality beneath the site or, more categorically, not at downgradient receptor. p10

Prof Brassington, however, is having none of that:

The length of the travel time involved is critical in determining the development of the chemistry of the water that discharges from the springs. 35

Let’s repeat that for the benefit of those championing Aggregate Industries’ scheme – be they consultants, the EA or Devon County Council – who seem so hard of understanding:

The length of the travel time involved is critical in determining the development of the chemistry of the water that discharges from the springs. 35

In fact:

...the whole of the flow path from the ground surface where recharge water starts its journey downwards through the unsaturated zone to the water table where it becomes groundwater which then flows through the saturated zone to emerge at the springs is essential in the development of the water chemistry. The removal of part of the unsaturated zone where flow velocities are far less than in the saturated zone will result in the greatest impact on the water chemistry. 21

It makes you wonder how knowledgeable Aggregate Industries’ experts really are. Or indeed, the EA for being taken in by their tales.

In 2015, Amec was trying to convince people that:

transit of water through the unsaturated zone is considered to be fairly rapid due to the intergrannular and fractured nature of the BSPB and therefore the thickness of the unsaturated zone may not be as important. 2.5

Again in 2017, in response to DCC’s Reg 22 request – that raised questions over unsaturated zone storage and flood risk – Amec argued:

...recharge reaches the water table in the BSPB through unsaturated thicknesses of between approximately 3 and 10 m within between 1 and 3 days. This is consistent with the conceptual model for relatively rapid recharge occurring in the BSPB (i.e. days rather than weeks or months). 2.7.3

This is rubbished by Prof Brassington, who reminds Wood’s so-called experts that groundwater flow through the unsaturated zone occurs as a "piston flow resulting in an equal volume of water entering at the top of the unsaturated zone being released from the bottom to enter the saturated zone beneath the water table" and that:

It is important not to confuse this type of flow with one that suggests that the recharge from any rainfall event reaches the water table rapidly through fracture flow 60

Prof Brassington says the time groundwater takes to travel through the unsaturated zone should not be measured in days, weeks or months – but in YEARS:

According to Wang et al (2012) the unsaturated zone velocity for the Sherwood Sandstone Group falls in the range 0.6 – 2.3 m/year with a mean of 1.06 m/year (these values were summarized by Chilton and Foster (1991)). The values for unsaturated zone flow rates are several orders of magnitude (three to five) lower than flow velocities in the saturated zone. 59

In the case of Straitgate:

... the lack of cement means that the rock is basically a pebbly sand with layers of silt and clay; consequently there are no fractures and so there will be no bypass flows. 59

It is simple to calculate the loss in groundwater travel time caused by the loss of some 7 m of the unsaturated zone as it is 7 × 1.06 years = 7.42 years. 62

YEARS, NOT DAYS. Much as indicated below – and widely elsewhere:

That’s an amazing, fundamental mistake for Amec to have made, and for the EA to have overlooked. It makes you wonder how many other things these parties have got wrong about Straitgate's groundwater.

Removing much of the unsaturated zone – and its capacity to store large amounts of slowly moving water – will naturally have huge impacts on spring flows and flood risk. It is however the change in groundwater chemistry that Prof Brassington has focused on. Indeed, in his original report a year ago he warned:

…the proposals will cause a large reduction in the thickness of the unsaturated zone that will reduce the time for the recharge to percolate through this zone. This reduced period will mean less time for rock/water interaction and will result in a less chemically mature groundwater that is more acidic than it is at the moment. These are reasons why the application should be refused by Devon County Council. 5.13

Given the EA’s dismissive attitude – Prof Brassington has raised those warnings again in his new report:

The water chemistry develops as the water percolates through the unsaturated zone and then, once it has reached the water table, it flows through the aquifer. A series of rock/water interactions takes place along this flow path causing the chemistry of the water to change as it moves along. These interactions are slow and so the time taken for the water to reach the springs will determine the concentration of the dissolved minerals, the balance between the dissolved minerals, the pH and the electrical conductivity of the water. 35

Prof Brassington shows that for Cadhay the period for rock/water interactions would be HALVED if Aggregate Industries’ proposal went ahead:

The EA calculated the Source Protection zone (Walford, 2013) using a similar method to the one adopted here. The map they have produced is shown below in Figure 11. The distance of the flow path from the recharge area in the proposed quarry to the Cadhay spring has been marked on the map. 64

Calculations of the time that groundwater takes from rainfall percolating into the ground to the groundwater emerging from a spring have been carried out for the Cadhay spring that supplies Cadhay House and estate. The water takes almost 15 years to make this journey and if all but 1 m of the unsaturated zone is removed this reduces some 50% of the total travel time. 76

Not only that. Whatever Section 106 conditions are made – and a leading planning lawyer has already shown that draft legal assurances for alternative water supplies are “unfit for purpose” – Aggregate Industries would be long gone:

It shows that the time taken can be expected to be sufficiently long for the quarrying to have been completed by some years by the time that the water quality changes have occurred. This will provide scope for AI to deny causing the problem. 77

No wonder Aggregate Industries had 'no objection' to including Cadhay and its mediaeval fishponds and its ancient woodlands in a Section 106 last year.

Prof Brassington warns:

The impact on the travel time also means that the deterioration of the groundwater chemistry will be a permanent change and it will not be possible to reverse it. 77

The concern for the 100 people or so who obtain their water supply from these springs is that the water make up will substantially change and a reduction in the pH will mean that the water is too acidic for drinking without treatment and it will dissolve metal pipework and storage tanks. It will affect the chemistry of the water in the streams that will impact on the Cadhay Bog and Cadhay Wood wetland habitats in the ancient woodland as these depend on the stream flows. 56

Furthermore, Prof Brassington warned in his original report that Aggregate Industries' model of the maximum water table – the base of any quarry – is not correct, as we posted in Boreholes at Straitgate ‘will have groundwater levels lower than local water table’.

In his new report, Prof Brassington is again at pains to remind us – or at least remind Aggregate Industries’ consultants and the EA who should know about these things: "the depth of a borehole and its location within an aquifer have a significant influence on the water level within it":

The use of fully penetrating piezometers to monitor the elevation of the water table as is the case at the Straitgate Farm site, means that it can be expected that the water levels in the piezometers will reflect a lower water level than the correct water table due to the three-dimensional aspect of groundwater flow. The MWWT grid will therefore be modelled from levels lower than reality, which will enable AI to excavate below the maximum water table. 73

Quite how this planning application can go any further forward – as it currently stands – with so many errors in the environmental information, and with so many warnings from such an eminent independent expert in hydrogeology, is anybody’s guess. An invasive sand and gravel quarry at Straitgate Farm, is – as Prof Brassington so clearly points out – no way to treat "a fragile groundwater system" and no way to treat a water source depended on by so many, including an important Grade I listed house and gardens.

The EA and ‘our precious groundwater resources’

Straitgate has occupied a disproportionate amount of the Environment Agency's time over the years – right back from when it was put forward for the Minerals Plan in 2012. At that time, the EA warned:

The importance and value of this area may be under-represented by the appraisal undertaken so far. When our groundwater team map the Source Protection Zones (SPZs) for all of the private water supplies in this area I expect that [Straitgate] will be an important part of their catchment areas.

Our policy on the protection of water resources from changes to aquifer conditions (see general comments below) will govern our response to this and every other site. The number of private water supplies suggests to me that this would be a difficult site to take forward. Similarly, if this area is shown to be a significant part of the catchment for the water features near Cadhay, its deliverability as a viable site would seem unlikely.

Cadhay's water features? Here's a photo of one of the mediaeval fishponds, integral to the setting of the Grade I Tudor manor house:

Only last month, in relation to Cadhay, we posted that Aggregate Industries' legal assurances for alternative water supplies were – according to one lawyer – "unfit for purpose".

What does the EA mean when it talks about SPZs? Here's the SPZ that the EA put in place at Straitgate in 2013 – across the area that AI wants to quarry – in an effort to protect Cadhay's water supplies:

Environment Agency

But it's not just Cadhay that has an SPZ. Many private water supplies rely on the groundwater at Straitgate for drinking water. As The Environment Agency’s approach to groundwater protection states, "all groundwater abstractions intended for human consumption or food production purposes have a default SPZ1".

For those unclear of the EA's responsibilities, the above document explains:

We are the Environment Agency. We protect and improve the environment and make it a better place for people and wildlife.

We operate at the place where environmental change has its greatest impact on people’s lives. We reduce the risks to people and properties from flooding; make sure there is enough water for people and wildlife; protect and improve air, land and water quality and apply the environmental standards within which industry can operate.

Acting to reduce climate change and helping people and wildlife adapt to its consequences are at the heart of all that we do.

We cannot do this alone. We work closely with a wide range of partners including government, business, local authorities, other agencies, civil society groups and the communities we serve.

The EA also tweets about "our precious groundwater resources". Here's a few relevant to Straitgate:

The ‘Water Cycle’ – Don’t forget that #Groundwater & #SurfaceWater are intrinsically linked & they both cannot exist without each other within the natural Water Cycle

Groundwater from our #aquifers provide essential #baseflows to our rivers enabling them to flow as watercourses pic.twitter.com/KsjR4xhWpz

— Geoscience EnvAgency (@GeoscienceEA) February 18, 2019

The #watertable is a fundamental reference point used by #hydrogeologists representing the top of the saturated zone in our #aquifers & seasonally fluctuates with infiltrating rainfall. It tends to mimic shape of the ground surface being deeper under hills & shallow under valleys pic.twitter.com/nqeGBOkJj9

— Geoscience EnvAgency (@GeoscienceEA) March 1, 2019

Ever dug down & come across a damp zone before digging deeper to find water? This is called the ‘capillary fringe’ & it sits above the #watertable Forms by capillary action as #groundwater seeps upwards. In fine grained rocks can be >10m & coarse sandstone no more than several cm pic.twitter.com/TIajGhIcUG

— Geoscience EnvAgency (@GeoscienceEA) March 5, 2019

AI’s legal assurances for alternative water supplies “unfit for purpose”

It’s not just Theresa May hunting for illusory "alternative arrangements":

I asked Theresa May's spokesman which potential technological solutions to avoid the backstop, the government has identified so far:

"We want to begin exploring exploring these options as soon as possible."

— Adam Bienkov (@AdamBienkov) January 30, 2019

Aggregate Industries has also been asked about alternative arrangements: alternative arrangements for peoples’ drinking water supplies in the event of a failure caused by any quarrying at Straitgate Farm.

A letter has been sent to DCC by solicitors acting on behalf of Cadhay – a Grade I Tudor manor house reliant on the groundwater from Straitgate for its drinking water supplies and listed mediaeval fishponds.

In 2017, we posted So what happens if people lose their water supplies? DCC had asked AI:

The planning policy section of the application includes the text from the Devon Minerals plan, ‘any proposal should include provision for alternative supply in the event of derogation of private water supplies resulting from mineral development’. However, there is no detail on this in the body of the report. Full detail should be provided including proposals for either a bond or legal agreement dealing with this matter.

We pointed to AI’s Reg22 response dealing with the matter:

In the event that there shall be interference with any of the private water supplies (as indicated on plan to be agreed with Devon County Council, in consultation with the Environment Agency) or an inability to draw a satisfactory water supply in respect of any of the private water supplies and such interference or inability to draw a satisfactory water supply is in the opinion of the County Council, in consultation with the Environment Agency, on the balance of probability, attributable partly or wholly as a result of the winning and working of minerals at Straitgate Farm then AIUK shall forthwith at its own expense take such action or make temporary or permanent arrangements for the provision of any alternative or additional water supply to the users of the private water supplies as shall be necessary or appropriate in the opinion of the County Council, in consultation with the Environment Agency, to replace or compensate for the interference or inability to draw a satisfactory supply to the extent that the same is attributable to such activities associated with the winning and working of minerals at Straitgate Farm, such provision to be kept in place until a satisfactory water supply is reinstated. 2.8.1

AI’s assurances hardly provide much comfort. As we said at the time:

Locals will no doubt wonder about the interpretation of "any alternative". Would it be bottled water, emergency tanker supplies, or what? Some properties are miles from a mains supply, but if mains were to be installed, there's nothing in AI's legal blurb to say who would pay the water bill for ever more; a water bill that for farms or Cadhay could be enormous.

As we posted in Another AI quarry in Devon non-compliant with planning conditions:

And what hope is there for people who lose those supplies, if there's such disregard for timeliness and urgency? How long would it take – "in the opinion of the County Council, in consultation with the Environment Agency, on the balance of probability..." – for DCC to swing into action? How long would it take – "in the opinion of the County Council, in consultation with the Environment Agency..." – for AI to restore alternative supplies, temporary or permanent? How long would people be without water? Days? Weeks? Months? If AI were to be found guilty – "on the balance of probability" – the company promises action "forthwith". But does that mean 2 weeks, 2 months or, as above, 2 years? Does than mean before or after the consultants and lawyers have had their say? What's that promise worth without a number? What's that promise worth with such failings and lack of urgency elsewhere in the county?

But it’s not just us who have raised concerns. In December, a letter was sent to DCC by solicitors acting on behalf of Cadhay. This letter has now apparently been forwarded to AI. With regard to AI’s paragraph 2.8.1 above, with our emphasis:

At paragraph 2.8.1(i), draft wording has been proposed setting out the circumstances under which the applicant would be required to provide alternative water supplies and/or compensate for the disruption. With respect to the lawyer who (presumably) drafted this provision, it is so full of caveats, provisos, legal tests, consultation requirements and optionality as to be unfit for purpose.

The main issue, which the draft provision fails to recognise, is that any interruption to the supplies will have an immediate effect on Cadhay, as those supplies are needed for the hospitality and wedding businesses operating at the property. In contrast to this immediate need for water, the applicant has proposed a tortuous legal mechanism for establishing causation, liability and remedy, none of which will actually deal with the immediacy of the problem. In short, whilst the parties to the s106 agreement [an agreement to which Cadhay would not be a party] argue about the operation of this provision, Cadhay’s business could fail.

This concern is further reinforced by the fact that the mediaeval fishponds, which are listed in their own right and strategic to the setting of Cadhay, rely on water from Straitgate. If the ponds were reduced to a muddy mess due to the development impacting the supplies, the ponds would cease to be the selling point that they currently enjoy (due to their photogenic qualities) and instead become an eyesore, turning away both customers and open day visitors. Taken together, the impact on my client’s business would be significant, leading not only to a serious risk to his business but also a genuine risk that the upkeep of the outstanding Grade I listed building would be compromised.

Perhaps most importantly, the proposals at 2.8.1 do not give details on any of the following fundamental points:

* where are the alternative water supplies;

* how reliable are those supplies;

* what is the quality of the water from those supplies;

* how quickly can sufficient supplies be made available; and

* what rights does the applicant have to secure those supplies?

As above, the applicant is underplaying the significant damage that would be caused by any interruption to Cadhay’s water supplies, and the consequential need to have robust and detailed arrangements in place to ensure that supplies are maintained at all times. The applicant’s proposed planning obligations fail at every level in relation to matters of detail, and Cadhay cannot accept such a situation.

As the Council will be aware, as a matter of law the ES is required to properly set out the mitigation measures proposed to address any significant adverse impacts likely to be caused by the development, following which the local planning authority can then assess those mitigation measures. In other words, if there’s a problem which might be caused by the development, the LPA must know how that problem will be mitigated, and then assess such mitigation.

In relation to the security of water supplies, the applicant has not provided any details of the proposed mitigation measures in the event that the supplies are disrupted: the proposed planning obligations are bereft of any such details. Without having details of the proposed mitigation, the Council cannot properly assess the environmental impact of the scheme.

Of course, this doesn't only affect Cadhay; there are other people miles away from an alternative mains supply. AI needs to come clean on exactly how it would replace water supplies in the event of a failure.

And mining companies are not unfamiliar with failure. Ask people in Brazil; ask people in Mozambique; ask people in Northumbria left without water for four years after quarry operators were allegedly working below the water table; ask a small rural community on the outskirts of Edinburgh left without clean drinking water for weeks by Tarmac:

"We are being bullied and ignored by a big PLC business that controls one of our basic rights – to have fresh water. Without water, normal life quickly grinds to a halt."

Wouldn’t a Section 106 planning agreement sort things out? Well, even if appropriate assurances could be drafted, it’s not even clear who would be covered – Cadhay, supposedly protected by the EA’s SPZ, certainly wasn’t covered in AI’s original application; AI has so far refrained from identifying specific properties, saying only "private water supplies (as indicated on plan to be agreed with Devon County Council, in consultation with the Environment Agency)".

We’ve also posted about AI breaking S106 water monitoring agreements. We’ve posted about AI operating asphalt plants without planning permission. We’ve posted about AI running bagging operations without planning permission. We've also asked What’s the chance that AI would stop digging when it gets to the water table?

So, if there are recent examples locally where AI has had problems adhering to a Section 106, should we instead draw comfort from assurances the company has made in its Environmental Statement? As referred to by Cadhay’s lawyers, and as we have previously posted:

(3) An environmental statement is a statement which includes at least —(c) a description of any features of the proposed development, or measures envisaged in order to avoid, prevent or reduce and, if possible, offset likely significant adverse effects on the environment;

Again, as Cadhay’s lawyers point out, AI has not provided any details of proposed mitigation measures. Despite AI's consultants unsurprisingly claiming "there is not expected to be any direct impact on any groundwater dependent features" 6.2.1, we have already posted about Environmental Impact Assessments: Are they worth the paper they’re written on? how:

Friends of the Earth bemoan the fact that:

In practice, the [Environmental Statement] is often a sales document for the applicant and there have been increasing calls for an independent commission of EIAs to take them out of the hands of those with a vested interest in seeing schemes approved.

The quality of ES can be surprisingly poor, with developers often keen to do the least possible to get the application through, so it is vital local people go on asking critical questions of the applicant and local authority planners.

A paper titled: Myth and Momentum: A Critique of Environmental Impact Assessments complains:

EIAs are now often contracted to the lowest bidder, with a focus often more on achieving mandated deadlines, rather than on product quality. In some cases, more expertise and resources may be put into winning a contract than completing it, with the important scientific work being done cheaply by newly graduated bachelor’s degree holders or inexperienced interns.

In that same post, we pointed out that AI’s EIA has been riddled with fiction; that consultants Amec Foster Wheeler (now Wood) have produced an assortment of hydrological predictions which have already failed – again and again and again; that Amec refused to provide information on tolerances; that some of Amec’s reports had even been whitewashed.

Why are local people so concerned? Well, in the Devon Minerals Plan DCC put a line through the 1m to protect drinking water supplies, and AI plans to dig all the way down to the water table - without leaving the typical 1m unquarried safeguard, whilst other quarries – here and here for example – are approved with a 2m safeguard above maximum groundwater levels.

So, once AI submits its next batch of documents to DCC in answer to questions – and who knows when that will be (an inexplicable 18 months has passed since those seemingly difficult questions were raised) – local people should respond to DCC's planners and ask them to detail exactly how AI would provide alternative drinking water supplies in the event of supplies becoming lost or polluted – particularly to those who are miles away from any mains supply.

According to the people in Northumbria, laying three miles of pipework costs some £500,000.

The importance of leaving 1 metre...

It is extraordinary that the issue of leaving 1 metre of unquarried material above the maximum water table to protect drinking water supplies and prevent flooding is still a matter of discussion between Aggregate Industries, the Environment Agency and Devon County Council. This matter should be non-negotiable.

Perhaps someone might explain to those around Straitgate currently reliant on springs and wells for their drinking water supplies with no mains replacement, why the matter appeared non-negotiable at Hanson's Town Farm Quarry at Burlescombe: same geology, same planned restoration to farmland, but far fewer people reliant on private water. Unlike AI, Hanson was straightforward and upfront:

The scheme proposes extraction within the Pebble Beds to 1m above the highest recorded water table level. C3.1

After all, a 'freeboard' of at least 1m is typical where drinking water supplies are at risk. Is it to be that in Devon we have one rule for one operator and one rule for another? 

In contrast to the SPZ running across Straitgate, the salient points for Town Farm were:

There are no groundwater protection zones shown on the Environment Agency web site in the vicinity of the site… The nearest water supply is [50m] to the west of the proposed quarry extension. It is understood this is a potable supply is supplemented by mains water should it be required. The elevation of the water level and the geology indicate that the well is fed by the Lower Marls and not directly from the Pebble Beds. C2.6

Why was it necessary to leave 1m above the water table unquarried? Hanson recognised that:

The unsaturated zone above the water table affords protection of the aquifer from surface pollution, allowing adsorption, attenuation and degradation of contaminants prior to reaching the water table. Removal of lower permeability clay layers from within the Pebble Beds could also remove some protection from the groundwater. During the operation of the site pollution may arise from the extraction and restoration activities. The pollution may be in the form of fuel, lubricants and other fluids associated with the operator’s machinery. C3.1

You would think that all this was pretty standard. Elsewhere, a hydrogeological expert advised:

Maintaining a 1 metre separation between the base of the excavation and groundwater provides additional time to clean up any spills, provides additional capacity of the soils and unsaturated zone to attenuate some contaminants, and reduces the possibility that any fill used post-quarrying may be inundated, with the increased risk of leaching on contaminants that this would entail. 3.4

Future land uses, after site closure, will be limited by the available unsaturated zone thickness. 3.8

Post-restoration, due to the decreased depth to groundwater and more limited ability of the ground to attenuate contaminants, it is appropriate to impose restrictions on land use. Although nitrate and bacteria, as might result from intensive agriculture, are not contaminants of concern for the quarry and cleanfill operation, these may pose a risk to groundwater quality for downgradient users if the post-rehabilitation land use causes discharges of these contaminants (including diffuse discharges). 6.1(g) 

Through quarrying the exposure pathway for any contaminants has been modified. This means that there may be rapid access to the groundwater system for any contaminants, including pathogens. 6.2

When soil is first reinstated, its ability to attenuate contaminants will be lower than for a well-established soil. In a well-developed soil, the top soil grades into the underlying gravels, allowing for further attenuation of nutrients and pathogens. The soil condition would improve with time, but depends on soil management practices. 6.5

So, it’s not just contamination from quarrying that we have to worry about, it’s contamination from future land use, farming or otherwise - be they nitrates, chemicals or worse. Amec's Hydrogeological Assessment is silent on this matter. Again, you would think it's all common sense; the more sand and gravel left, the more subsequent protection against pollution in drinking water sources. 

The same expert also stated that:

Determining the highest groundwater level with confidence at a site is difficult, and the interpreted highest groundwater may not be accurate to within several metres, because almost invariably, there is not a shallow well with a long term record of water levels at the site. Because of this, a degree of conservatism is often required when using interpreted highest groundwater levels. 3.6 

Amec doesn't know with any certainty where the maximum water table level at Straitgate is either:

...there is uncertainty about how smooth the [seasonal groundwater elevation] transition is because there is no piezometer in the centre of the Site and there is the possibility for steps in the water table related to faulting 2.4 ...unmapped local faulting... 3.1 ...the two [maximum water table grids] therefore represent just two of the many possible interpretations of the data which themselves are based on an incomplete parameterization of the detailed groundwater dynamics of the site 4.2 Groundwater levels do not fluctuate evenly across the site... 4.2 Mineral extraction down to this [maximum groundwater level] surface would be dry for the vast majority of time as on average, groundwater levels are expected to be below this level. 6

In any case, it is highly unlikely that groundwater monitoring over the last 2 years or so will have recorded the maximum possible water table elevation.

On the subject of runoff - a concern to downstream communities around flood-prone Ottery St Mary - Hanson acknowledged:

During the operational phase, the excavation of the quarry will change the response to rainfall with the potential for greater and more rapid surface water runoff than would occur naturally over a vegetated surface C3.2

And Amec also thought the 1m was important when it assessed the runoff at Straitgate:

By maintaining an unsaturated zone thickness of at least 1 m (which increases to 5 m or more in some locations during summer months), the ability of water to infiltrate into the ground is not expected to change as the hydraulic conductivity and infiltration capacity remains the same. All that may change is the ability of the unsaturated zone to “store” water after intensive rainfall events... Bearing in mind that a certain proportion of this rainfall would have naturally ended up as runoff and evaporation then a 1m unsaturated zone should be enough to accommodate this intense rainfall event... The removal of the unsaturated zone down to a level of 1 m above that defined by the maximum winter water level will mean that any change in the recharge / runoff split, if it occurs, may be seen in the winter months and during very high rainfall events... It is not possible to quantify this possible change [in runoff] with any great accuracy. ...the assumption has been made that there may be a 20% increase in runoff. 5.1

Amec’s Flood Risk Assessment also stated:

It is proposed that no excavations be conducted beneath the water table, this includes up to the 1% AEP extreme high water table level, and that an unsaturated buffer is also maintained between the water table and the surface. Groundwater ingress is consequently not considered a risk at the Site. 3.5.3

It would seem utterly perverse if AI now claimed this 1m buffer was not needed; the EA says peak rainfall intensity could increase by 20% in 2055-2085 and 30% in 2085-2115.

Leaving 1m unquarried above the maximum water table should be a precautionary given; 1m allows for a margin of error and a margin of safety, because the maximum water table is not known with accuracy; faulting across the site is not known with accuracy; excavators would not dig with accuracy; future climate is not known with accuracy; future land use pollutants are not known with accuracy.

At Town Farm, there were two properties reliant on private water. Here's who relies on Straitgate's water:

AI doesn’t want to leave 1m to protect water supplies; would it like to leave 2m?

It’s obviously pretty standard in quarry applications to leave at least 1m above the maximum groundwater level when there is any risk to surrounding water supplies - here and here are just two examples of many.

Aggregate Industries would dearly like to reduce this unquarried metre to nothing, if given half a chance; it obviously couldn’t care less about peoples' drinking water supplies.

But AI should count itself lucky that stiffer groundwater restrictions have not been specified by the Environment Agency. In the quarry extension in Kent, referenced in the post below, Condition 37:

No mineral extraction shall take place... within 2 metres of the maximum recorded depth of groundwater... Reason: To minimise the risk of pollution of the public water supply.

Two metres have also been specified here and here, and also Switzerland, home to AI's parent:

The Swiss federal government has banned the extraction of sand and gravel from areas where drinking water is sourced.

permits shall not be granted in groundwater protection zones, including designated drinking water sources;

In a limited number of exceptions, gravel may be removed from above the groundwater level "provided a protective layer of material is left above the maximum groundwater level possible".

During quarrying the protective layer of material is required to be [at] least two metres above the highest maximum 10-year groundwater level.

For surrounding residents relying on Straitgate for their drinking water, the matter is important; AI made claims about 'dry working' at Venn Ottery.

And the reason for the delay until 2016?

It's unreal. At this late stage of the application process, Aggregate Industries is still having difficulty with agreeing to leave a 1m standoff of unquarried material above the maximum water table to protect drinking water supplies and stream flows.

DCC asked AI in the middle of October to clarify the subject. Two weeks later, the matter remains unresolved and "will be the subject of a meeting between AI/Amec/the Environment Agency and DCC as Flood Authority in the second week of November".

It’s disgraceful that AI is still not being straight on such a critical issue. It makes a mockery of AI's claims that "the applications were the culmination of three years of careful planning and consideration". The importance of leaving this 1m of unsaturated material has already been acknowledged. AI's ridiculous attitude is even more shameful given that the company proposes no Section 106 to safeguard Cadhay’s water supplies, the subject of an Environment Agency SPZ that stretches across the proposed excavation site.

Since AI is unable to straightforwardly confirm that this 1m would indeed be left unquarried, one can only assume, given the list of attendees, that AI wants to renegotiate the condition and thereby reduce the protection for local peoples' drinking water, the protection for wetland habitats in ancient woodland, and the protection for downstream communities against flooding - the condition confirmed by the EA back in July, the condition detailed in DCC’s draft Minerals Plan, the condition assumed by AI's own hydrogeological consultants:

The proposed quarry at Straitgate Farm would work the mineral dry and to a proposed limit of 1m above the highest predicted water table.

It is difficult to identify if “winter flashiness” is due to reduced unsaturated zone thickness or other factors that affect recharge… Within the proposed development the establishment of a 1m freeboard over and above the highest known water level provides for this eventuality.

In its letter, DCC warned AI:

Given the importance of this point, to you as the proposed operator, and evidently to the MPA and the EA who were both of the understanding that you had agreed to this restriction. I am now asking you to clarify in writing whether you are intending to work to the proposed levels set out in the Amec technical Note to the Policy Team and the EA (and on which their recommendation was clearly based) or whether you wish for the MPA to consider your proposal as working to the highest measured level of the winter water table without the 1m standoff.

You will understand the importance of this point and the need for absolute clarity in your response as it has serious implications for the further progress of this application.

DCC has confirmed that AI's response will be posted on the website with the application documentation, if and when received.

Environment Agency

For those worried about losing their water supply…

More than 100 people are reliant on Straitgate for their drinking water. On the question of security of supply, AI says that "draft Heads of Terms are provided for discussion with DCC":

In the event that in the opinion of the EA, as party to this agreement, the balance of probability is that contamination or interference of groundwater boreholes or private water supplies or the inability to draw satisfactory water supply has occurred partly or wholly as a result of the wining and working of minerals at Straitgate Quarry then AI shall forthwith make alternative temporary and/or permanent arrangements for water supply to the users affected at AI’s cost and liability, proportionate to the cause. 3.4

AI proposes the following letter of 'comfort', but, if the loss or contamination of supply is disputed, water users could be left with a legal headache and a large bill:

But AI’s Section 106 agreement 3.5 is not all that it seems, since Cadhay Spring, which derives its water from Straitgate under protection of an Environment Agency SPZ and supplies 60 people at Cadhay and surrounding properties and 2,000 people each year in its Tea Room, is notably excluded:

The monitoring schedule included as part of the s.106 agreement shall include [list of springs and wells, not including Cadhay Spring]. In addition, monitoring will continue at Cadhay Spring. 3.6

Presumably, AI is not wholly confident that it would not impact this water supply in some way.

And on the subject of fracking... and groundwater

Fracking may be geologically improbable in East Devon - Cllr Claire Wright’s blog gives more details - but this helpful map from Friends of the Earth shows the areas being offered up for licensing, including parts of Devon. What it also shows are the groundwater Source Protection Zones imposed by the Environment Agency - including those to protect private water supplies around Straitgate.

AI’s Scoping Request now has SLR claiming that because "...the intention is only to extract mineral from a “dry working option” (above the water table) at Straitgate Farm. It is considered, therefore, that the proposed development would not result in any significant effects on the water environment".

It’s a big claim, and it will be interesting to see if the Environment Agency agrees. Because removing soil, overburden and 1.2 million tonnes of unsaturated sand and gravel above the saturated zone would certainly appear to have the capacity to change the hydrological regime in some way - be it recharge characteristics, surface run-off, or response to pollution events.

Of course, the corollary of SLR's claim is that the future “wet working option”, the improbable 'Stage 2' of AI's plans, would result in significant effects on the water environment.

The cumulative effect

Let’s summarise what’s happened since 2012, when DCC decided that Straitgate was the best of 10 sites in East Devon to put forward as a Preferred Site for sand and gravel in its new Minerals Plan.

In 2011/12, DCC performed a "detailed appraisal" of each of the 10 sites to find those with "the least constraints and most likelihood of potential delivery". It found issues with all of them - but apparently Straitgate (S7) was the only site without a ‘showstopper’; of course, it was also the only site owned by Aggregate Industries. DCC's belated Sustainability Appraisal - a process which did not inform the rejection of the alternative sites as it should have - found even more constraints. In fact, Straitgate had more "significant negative impacts” than almost any other site; the Environment Agency remarked "It is apparent from the SA that some of the excluded sites may [be] preferable in environmental terms".

Since DCC’s original appraisals, Straitgate’s list of issues has only grown. We now know that:

Natural England, the Environment Agency and Exeter Airport all have unresolved concerns;

Part of Straitgate has now been designated by the Environment Agency as an SPZ - Source Protection Zone - indicating its importance to the drinking water supplies at Cadhay. The EA had made it clear before the new SPZ that "if [Straitgate] is shown to be a significant part of the catchment for the water features near Cadhay, its deliverability as a viable site would seem unlikely”;

Cadhay Bog, with its ancient woodland and wetland habitats, is now recognised in all likelihood to have been wooded for up to 10,000 years, being a remnant of the 'wildwood' that colonised Britain after the last Ice Age. According to SLR, AI’s consultants, Cadhay Bog is “in very good condition” with "significant biodiversity interest” and "the ecological site most at risk from the proposals”;

Straitgate has a population of dormice - a European Protected Species; AI will need to convince Natural England that a quarry and the removal of almost 2 miles of ancient hedgerow dormouse habitat is "preserving public health or public safety or other imperative reasons of overriding public interest including those of a social or economic nature and beneficial consequences of primary importance for the environment”, has “no satisfactory alternative” and “will not be detrimental to the maintenance of the population of the species concerned at a favourable conservation status in their natural range”;

And now, the fields at Straitgate are also revealing signs of Iron Age settlement that will probably require a very full archaeological excavation before any quarry could ever take place.

Any of these new developments might have been considered ‘showstoppers' in their own right, but when you combine them all, and then add them to the ones we knew about before - 100 people and 3 farms relying on the site for drinking water, increased birdstrike risk to aircraft from ponding, visual impact on AONB, flooding, effect on Grade I & II listed buildings, off-site processing using public not internal haul roads - then the cumulative effect of any quarrying makes Straitgate look a non-starter. Sometimes you wonder whether DCC couldn't have picked a more constrained site if it had tried.

Of course, if DCC does go forward with Straitgate as its preferred choice, it will somehow have to persuade a public inspector of the soundness of relying on a site with potentially as little as 6 years, or less, of sand and gravel... and a list of issues as long as your arm.

‘Gravel extraction application rejected by Three Rivers’, reads the headline

Here’s a story that appeared over the Christmas period. It's about what happened in Hertfordshire when the Environment Agency objected to a sand and gravel quarry:

...the Environment Agency said: "We believe that the proposed development would pose an unacceptable risk to groundwater quality and potable water supplies, and we recommend that planning permission should be refused on this basis."

District councillors unanimously agreed that the application to amend these conditions of extraction... should be rejected by Hertfordshire County Council. 

The officer's report made clear "In determining applications for mineral extraction, the NPPF confirms that local planning authorities should ensure that any permitted operations do not have unacceptable adverse impacts on... the flow and quantity of surface and groundwater”.

So why, when the Environment Agency has already made its views on Straitgate Farm so clear - even imposing SPZs to protect peoples' water supplies, is the site still in the frame?

What is different between this and Straitgate is that at least the applicant above "concedes that the seven year supply is already exceeded in Hertfordshire and recognises that, in these circumstances, there is a policy presumption against the granting of new planning permissions”. Let's remember that, at the end of 2012, Devon still had 16 years' worth of permitted sand and gravel reserves.