Monday, 31 July 2017

Piles of unprocessed pebbles sit stockpiled at Houndaller


Aggregate Industries began working its reserve at Houndaller, at Hillhead near Uffculme, earlier this year with mobile processing plant - see below; the same plant the company had in mind for Straitgate:
New mobile processing plant is to be installed in [Hillhead Quarry] and it is this plant which would be used to process the Straitgate minerals. 3.14
Houndaller has the same resource that's found at Straitgate: the Budleigh Salterton Pebble Beds. AI’s Reg22 response tells us that:
Extraction is currently taking place of c.4Mt of permitted sand and gravel reserves at Hillhead (Houndaller) Quarry. Permitted reserves of the sand rich sand and gravel deposit are expected to last over 10 years.
But from the piles and piles and piles of unprocessed pebbles - from this apparently sand rich deposit - stockpiled at the site after just a few months, it hardly looks like AI is short of gravel.

People will truly be at a loss to understand why Straitgate needs to be quarried, and hauled all the way to a site where mobile processing plant is seemingly unable to cope with pebbles larger than a few centimetres - a site that already has 4 MILLION TONNES of sand and gravel waiting to be processed.

What does Devon's newly adopted Minerals Plan say on this matter?
Policy M11 expresses a preference for the extension of an existing aggregates quarry to secure new resources rather than development of a new quarry, in recognition of the generally lower level of impacts on the local environment and communities and the benefits of utilising existing infrastructure. 5.3.7
And what about the 2.5 million mile haulage scheme to haul Straitgate material to Hillhead? M11 again:


If mobile processing plant can do it all, was the Blackhill extension secured on a lie?

Was DCC hoodwinked back in 2010, when Aggregate Industries wanted to secure a 6 year extension to its processing plant on Woodbury Common in the East Devon AONB?

Modification orders were served on AI to restrict quarrying at Blackhill Quarry in 1999, following the SPA and SAC European nature conservation designations on Woodbury Common; £6 million pounds was paid out in compensation as a result. Nevertheless, AI went on to secure permission to quarry an extension to the site in 2002, and later to process material from Venn Ottery until 2016.

So was DCC hoodwinked? If what AI now says is true, then it would appear so.

Back then the officer’s report read:
In order to assess the acceptability of continued working at Blackhill, it is necessary to consider alternative arrangements for processing sand and gravels from Marshbroadmoor [Rockbeare] and Venn Ottery Quarries. The Applicant has provided additional information on this aspect.6.15
... if mobile plant were to be used at Rockbeare the range of materials would be less, sales reduced, and the life of Venn Ottery Quarry prolonged.6.17
Even as recently as 2015, in its last application for Straitgate, AI was still banging the same drum:
The Blackhill Quarry [fixed] processing plant currently produces some 14 different finished products... substitution of the Blackhill plant with a mobile processing plant would severely restrict the output and product range. 8.29, 8.30
Now of course, AI has changed its tune. This means that either what it said in 2010 and 2015 - or what it's saying now - is untrue.

Why? Because faced with this recent Reg22 question from DCC:
It is understood that the mobile processing plant installed at Hillhead Quarry is incapable of maintaining the product range offered by the Blackhill Plant.
 If the resource at Straitgate and its potential product range is economically important then can the applicant explain why this proposal is not premature until such time as there is sufficient processing capacity to deliver the most efficient use of this diminishing resource? 8.4
AI responded by saying:
If the relocation of the Blackhill processing plant is not viable a number of options to process the mineral have been investigated... [including] on a campaign basis when required a mobile crushing plant consisting of... 
And, in contrast to 2010 and 2015, we're now told:
It is however possible to produce 20-5, 20mm all in or surface dressing mix by mixing on the ground with a loading shovel. Therefore not using the Blackhill plant is not fully restrictive on the product offerings. 8.4
"Mixing on the ground with a loading shovel" doesn't sound like the most elegant solution, more akin to something out of Bake Off, but it goes to show that nothing can be trusted; AI will say whatever it takes.

AI’s extraction plans are now down to 6 fields and 1.1 million tonnes


Aggregate Industries' planned extraction area for Straitgate Farm has shrunk - from 25.6ha to 22.6ha.

AI doesn’t tell us by how much this has reduced the total available resource, but we can work it out from a couple of documents. Appendix C tells us that the revised 1st phase now has 177,000 saleable tonnes, and the 2nd phase 363,000. The 3rd phase, which the Supporting Statement tells us "is expected to yield circa 740,000 tonnes of as raised sand and gravel", equates to 592,000 saleable tonnes after allowing for 20% waste. This gives a new total of 1.13 million saleable tonnes.

That's 500,000 tonnes less than AI’s 2015 planning application claimed could be recovered, and 90,000 tonnes less than the current application first put forward.

This of course assumes a quarry base:
If 1m of material was left above the MWWT, as is standard for other quarries where groundwater receptors are at risk, the resource available would be much less:
... excavating to a level 1m above the highest winter water table level would reduce the saleable tonnage by approximately 300,000 tonnes 8.77
As we have posted before, Straitgate Farm has already been a disaster for AI; when, English China Clays - AI’s predecessor - bought the farm in 1965 it believed it could lay its hands on 20 million tonnes.

Another accident on the same road AI wants to put 200 HGVs a day

A reminder of what's at stake

Mediaeval fish ponds at Grade I Cadhay reliant on water from Straitgate Farm.

Thursday, 27 July 2017

AI’s site access plans still have a major problem



Aggregate Industries has now had a chance to redraw its access plans onto the B3174 Exeter Road, to avoid the use of third party land, but, buried in the rash of new documents delivered this week, it’s clear the company still has problems.

Because the law of the land is that you can’t go around damaging other people’s property.


AI is relying on Birdcage Lane to access Straitgate Farm. It is also relying on felling 'Trees F, G and H' to do so - see the "photomontage" in the post below. The problem for AI is that Tree H - shown above - belongs to a third party. In SLR's "Landscape related matters" we find out that:
Devon County Council Highways have confirmed that they would not accept a “no dig” construction, due to HGV vehicles that will be using the road to access the proposed development… The “no dig” construction means that the works will potentially interfere with the root protection areas of Trees F, G and H and some of G15A as illustrated by Drawing R22/L/3-3-005 and it is likely they will be damaged by the development and need to be felled. 4.1
It’s bad enough that Trees F and G, two 20m English Oaks, would be lost.

But AI needs Tree H to be felled too. Very predictably therefore, AI’s consultants claim that "Tree H, an 18m high English Oak is already in a poor condition and it is recommended it is felled by the owner on the grounds of health and safety". Of course they would say that. But that’s for its owners to decide.

And, whilst AI’s own trees have been falling down along Birdcage Lane, this tree has caused no problems and will be good for another few decades yet, judging by yesterday's photograph.

In its Reg22 request DCC said:
If the applicant wishes to construct works within the highway that may impact on the neighbouring landowners assets (i.e. the mature oak tree) then the road construction must accord with BS 5837 and the applicant must indemnify the Highway Authority against any claims from the landowner regarding damage to the tree.
BS5837? "... a logical sequence of events that has tree care at the heart of the process":
To avoid damage to tree roots, existing ground levels should be retained within the RPA. Intrusion into soil (other than for piling) within the RPA is generally not acceptable, and topsoil within it should be retained in situ. 7.2.1
So, yet again, we are presented with a proposal that cannot be delivered without the consent of a third party. The views of this third party have been made perfectly clear already - on the ground and to DCC.

Tuesday, 25 July 2017

AI responds to DCC’s request for extra information - yet another consultation begins

Back in May, we posted that Aggregate Industries’ planning application for Straitgate Farm was in a mess. After several years of trying to make things work, DCC was still left requesting further information on a multitude of points; points ranging from cows crossing busy roads to provision for failing drinking water supplies; points including the Environment Agency’s objection, surface water management, the use of third party land, HGV access onto the fast-moving B3174, ecological impact, and the "unsustainability of Hillhead Quarry as a location for processing materials from Straitgate Farm".

AI’s response to these points has now been submitted and can be found here.

Local people, subjected over the last 17 years to countless consultations for two Minerals Plans and two planning applications, are thoroughly sick and tired of this never ending debacle. They now find themselves facing another mass of documents, and another consultation; a consultation, whether by design or not, that will begin at the start of the school holidays.

Has anything changed?

The extraction area has shrunk from 25.6ha to 22.6ha - but AI doesn’t tell us by how much this has reduced the available mineral resource.

Amazingly, there are still no figures on CO2 or air pollution emissions for AI's madcap 2.5 million mile scheme to transport the material to Uffculme for processing.

AI accepts that the displaced cows crossing the busy B3174 four times a day to reach replacement pasture "could be an additional hazard to users of Exeter Road" - over and above the 200 or so additional HGV movements a day of course - but thinks that some flashing lights should do the trick.

We'll post more in due course.

Monday, 24 July 2017

A catalogue of fiction


As DCC and the rest of us continue to wait for Aggregate Industries to respond to the Council’s Regulation 22 request for information on 61 substantive points, let’s remind ourselves of just some of the falsity that’s been uncovered so far, and ask ourselves:

If this is all such a good idea, why can’t AI tell it straight?

For example, on groundwater and resource: Back in 2015, AI confirmed: "a 1metre depth of unsaturated zone will be retained above the winter water table as per AMEC's technical note… the calculation of the 1.2Mt reserve was modelled to a surface 1metre above the highest winter water table". AI’s consultants AMEC also confirmed "The proposed quarry at Straitgate Farm would work the mineral dry and to a proposed limit of 1m above the highest predicted water table". In reality, AI intended to leave nothing above the maximum water table, and was eventually forced to say:
The resource declared assumes a working base that coincides with, and never drops below the Maximum Winter Water Table (MWWT)... the working method ensures that the floor of the excavation will always have at least 1.0m of unsaturated gravels beneath.
It’s now been shown that for large areas of the site groundwater levels do not fluctuate by 1m, so AI’s unorthodox working method could ensure no such thing.

On where to process: AI came up with a whole raft of nonsense as to why it couldn’t use nearby Rockbeare to process material from Straitgate, and on why there were 'exceptional circumstances' for using Blackhill on Woodbury Common instead - a protected area in the East Devon AONB:
It is considered that processing the Straitgate deposit at Blackhill Quarry is the only practical solution which is also the most sustainable solution.
without the Blackhill option the Phase 1 working [at Straitgate] is unlikely to be viable
Now, processing Straitgate material at Hillhead - despite being 23 miles away, despite being further from its target market - is apparently not only viable, but "logical" and "appropriate"; though obviously not logical or appropriate enough for AI to supply information on the associated CO2 and air pollution.

On using other people’s land: In its first application, AI wanted to use someone else’s land and claimed that "it has necessary rights over the surface to implement the proposals as presented." This was untrue. AI had no such rights, and the application was pulled as a result. In its second application, the company again planned to use someone else’s land, but neither informed the relevant third party, nor included details in the application; it’s the law to do both.

On whitewashed documents: Since the first application, the hydrogeology report has been whitewashed and large chunks of an ecology report have been removed.

On ecology: AI still hasn’t checked all the ponds around Straitgate for great crested newts. Consultants claimed the majority of ponds within 500m of the site boundary were not surveyed "due to lack of access permission". This was another lie; no landowner denied access. Interestingly, AI had no problem finding GCNs at Rockbeare, when it suited them to show why that site couldn’t be used for processing.


On traffic: Traffic numbers for the B3174 from AI’s consultant was another work of fiction, and bore no relation to Highways England counts two months earlier that showed almost 60% more traffic. Rather like the company’s planning application for Venn Ottery in 2010 claiming an average of 138 HGV movements a day, that bore no relation to the one random day we checked when it was 194.

On HGV accidents: AI’s consultants underplayed the number of HGV accidents on the B3180. They even covered up the fact that one of AI’s own HGVs had been involved in a collision with a coach.

It all makes this multinational and its consultants look like a bunch of cowboys, willing to say whatever it takes. It begs another question:

If AI can’t act honestly before winning any keys to dig, what hope would there be afterwards?

Still no sign of Blackhill plant coming down

You might have thought, since planning permission for processing at Blackhill Quarry expired seven months ago, that the processing plant would have been removed by now, or at least be in the process of deconstruction. But last week, breaking the peace in the murky mist of Woodbury Common, the plant was still noisily in operation.


DCC contacted Aggregate Industries for an explanation and was told:
The plant was run from 10.00am - 12.00am today (19 July 2017). It was confirmed that no material was processed by the plant. The machinery was activated to allow water to pass the system and ensure that the pumps are still active. The is a maintenance requirement to ensure that the machinery doesn’t cease and occurs 3 times a month.
If there really was no material being processed, you might ask yourself why this plant is still being kept operational. AI has, under the current consent, until the end of this year to remove it, but is no doubt awaiting the outcome of the Straitgate application to know what to do with it. Moving the processing plant to Hillhead is, according to DCC, only 'one of the options being discussed'.

Anyone concerned that the plant is running in excess of that described above can contact DCC.

Meanwhile, sales from previously stockpiled material at Blackhill continue. As with the plant, the Blackhill Quarry Restoration and Aftercare Scheme Revision F shows that the stockpile areas must also be restored by the end of the year.



Monday, 17 July 2017

Highways England to revisit Straitgate application


After Has Highways 'thrown a curve ball'? back in 2015, Aggregate Industries produced some cross sections - see below - so that Highways England could "fully understand" the impact of any quarrying directly next to the A30. Highways England originally wanted to see "that the full depth of the quarry excavation would not be lower than the A30 carriageway", but settled for a series of planning conditions, which were repeated in the most recent response:
The maximum extent of quarry workings adjacent to the A30 trunk road boundary shall not exceed that shown on drawing SF HWYS/1 and at all times a minimum buffer zone of 10m shall be maintained between the application boundary and the quarry workings.... Buttressing of extraction slopes shall be undertaken in line with the submitted plans with an agreed slope profile as shown on drawing SF HWYS/1... Reason: ...to protect the highway structural integrity and in the interest of the safe and efficient operation of the trunk road.
Last week, however, Highways England said they would revisit the application.

There have been quarry face slippages at AI's Manor Farm sand and gravel quarry in Kempsford, Gloucestershire. In an application to extend the quarry, the MOD was concerned about nearby landing lights for RAF Fairford. AI's consultants had said:
A 20m stand off to each lighting column will allow for a worst case situation where the quarry face could fail and cut back to an angle below the natural angle of repose (a gradient of approximately 1 in 3) and the face failure would not reach the base of the closest lighting pole. 1 in 3 is considered to be a stable slope in this type of material and 20m should therefore give the lights the protection required plus a safety margin beyond that. 10
Although the extraction proposals incorporate stand-off zones to protect boundaries there are concerns that in some instances that these might not be adequate. A request to review these limits to prevent site stability problems during and post extraction is strongly recommended to avoid slippage problems already experienced from the current quarrying works. 6.29
Prior to the commencement of works the applicant shall submit a plan for the approval of the Mineral Planning Authority detailing how the adjoining MOD land and the retained land on which aircraft landing lights are located will be protected from collapse or slippage whilst extraction operations are undertaken and until restoration has been completed.
And what has AI proposed next to the A30 dual carriageway? Not 20m standoffs, but 10m. Not 1 in 3 slopes, but as steep as 1 in 0.5.


Is DCC's LAA living in LAA LAA land?

It looks like someone at DCC has too much time on their hands now the Minerals Plan has been adopted.

DCC has just issued its 6th Local Aggregate Assessment, and with it some whizzy new projections and fancy new buzzwords; buzzwords such as "stress test" and "housing trajectory". The Executive Summary spells it out:
The ability of Devon to maintain land-won aggregate supply in the event of predicted increased construction levels has been tested by modelling ten year sales average and housing trajectory models. This test indicates that the crushed rock landbank will enable supply to be maintained, but that the present sand and gravel landbank would fall below the seven years minimum during the period 2020 to 2023.
This conclusion may seem odd to some people, given that at the end of 2016 Devon had sand and gravel reserves of 7.04 million tonnes, enough to last 13.4 years (based on a rolling average of 10 years sales data as advised in the NPPF).

So how has DCC arrived at this doomsday scenario "with the landbank dropping below [the required] seven years in 2020"?

DCC starts by saying that the LAA has "demonstrated that there is a correlation between land-won aggregate sales and housing completions in Devon over the past ten years" 4.2.2.

That’s hardly surprising for land-won aggregates you might think, but for sand and gravel the link appears more tenuous, given that while housing starts have bounced back from the recession, Devon’s sand and gravel sales continue to fall; given that in 2016, when housing starts hit a 9-year high, Devon's sand and gravel sales fell 14%.







But DCC has looked in its crystal ball. It has ignored headlines such as "A recession is 'almost inevitable'...", and says "the next ten years are forecast to see significantly higher levels of house building together with other infrastructure development" 4.2.2, and thinks that:
it is feasible to ‘stress test’ the capacity of Devon’s landbanks of land-won aggregates to cope with increased sales that mirror the predicted housing trajectory over the next ten years. This test has used two scenarios whereby, for the ten years to 2026, land-won aggregate sales follow either the ten year averages given in Table 9 [sic] or the forecast housing trajectory illustrated in Figure 9. 4.2.4
The bottom line of this stress test is that "the housing trajectory scenario would see the sand and gravel landbank exhausted by the end of 2026, with the landbank dropping below seven years in 2020" 4.2.5.

Amazing. But all this should be taken with a huge pinch of reality:

For a start, DCC has mis-calculated. As shown below, even using this fantasy scenario, the landbank in years as defined by the NPPF - "reserves" divided by "10yr average" - wouldn’t fall below 7 years until 2021, even with an inconceivable quantum leap in demand.

Secondly, "the average annual predicted sand and gravel sales in the housing trajectory scenario (0.705Mt)" 4.2.8, is a staggering 51% higher than sales in 2016 - and this is the year, as previously noted, that housing starts already sit at a 9-year high.

And thirdly, even DCC recognises:
A note of caution should be attached to predictions for future rates of house building, as experience shows that these may not be realised. In 2008, the Draft Regional Spatial Strategy for the South West identified an annual average housing requirement for Devon of 6,960 for the period 2006 to 2016, which exceeds by 71% the house completions achieved over the last ten years. 4.1.4
So, given that our council tax pays for these pie in the sky forecasts, is this 'stress test' of any use at all?

Or is it just a way of trying to help a certain aggregates company justify a planning application to quarry a small greenfield site in East Devon when there’s already 13 years of permitted sand and gravel reserves?

Friday, 14 July 2017

AI’s modus operandi

Many will be surprised to learn that it wouldn’t be Aggregate Industries' personnel rolling up their sleeves and quarrying Straitgate Farm. According to the company:

Contractors would haul any material off site.
Contractors would be engaged for soil stripping, earthworks and restoration.
And contractors are expected to be brought in to extract any sand and gravel.

It’s AI’s hard-nosed modus operandi: screwing down costs now it's part of the lean mean LafargeHolcim money counting machine, as workers facing the sack at AI’s Glensanda superquarry are finding out:
“They are simply sticking two fingers up at the regulations and the hard-working employees formerly of Hargreaves. This is a terrible time for GMB Scotland members working at that quarry.”
Glensanda has cropped up on this blog before. Material from the quarry is even shipped to Devon.

Thursday, 13 July 2017

When quarries come too close to people…

Residents in the area have complained for years about the dust. Two independent tests earlier this year found the dust contained high concentrations of crystalline silica, which could cause lung cancer and silicosis, an irreversible disease, over a long period.
"It is like sandpaper in my eyes."
Christchurch's city plan has no requirement for setback distances from quarries, but the Ministry for the Environment's good practice guidelines recommend a setback distance of 500 metres from those containing crystalline silica.
The quarry... was now within 90 metres of one house and 150m from several others.
At Straitgate Farm, in first world Devon, set back distances of 100m seem to be acceptable.

Wednesday, 12 July 2017

AI appoints new head of Aggregates division, and other news

Aggregate Industries has appointed Mike Pearce as managing director of its Aggregates division. Mr Pearce will apparently focus on "innovation, customer service, health and safety and sustainability." 

Indeed, AI's PR machine states that Mr Pearce:
has a responsibility to ensure the business acts responsibly and sustainably in each and every one of the communities that it is part of.
In which case he should have a good look at what his company is trying to get away with at Straitgate Farm. And ask himself whether a polluting, climate-unfriendly, multi-million mile haulage plan for Devon is either responsible or sustainable.

Obviously, AI hasn’t set the bar very high in the sustainability department, and yet, according to a new survey, sustainability will define leading firms over the next decade.
It is essential that companies address sustainability throughout their business operations and make it core to the way they do business
Meanwhile, in other news, the Serious Fraud Office has launched an investigation into Amec Foster Wheeler - AI’s water consultants.

Friday, 7 July 2017

Update

Groundwater: Aggregate Industries' Supporting Statement claimed that its seasonal working scheme "will always have at least 1.0m of unsaturated gravels beneath" when working down to a level "that coincides with, and never drops below the Maximum Winter Water Table".

However, this is impossible for large parts of the site since groundwater levels don't fall by 1m during the summer at three of the piezometers. This was pointed out to AI, who has responded by saying:
Although the unsaturated zone during the summer as measured directly at [PZ01] is approx 0.3m, at the nearest point of the proposed quarry (some 35m further down-slope in the modelled water table) the AMEC FW models demonstrate the difference increases to 1.002m. Heading south and north from this point the difference increases up to 4-5m.
But if that's the case, then Amec’s model is obviously flawed. The real data at PZ05 and PZ2016/001, towards the middle of the site, shows seasonal groundwater levels falling by no more than 42cm. And these are the maximum drops. Typically, groundwater levels at these locations fall by even less.




Mobile processing: On the issue of processing Straitgate Farm material with mobile plant, AI’s application had said:
New mobile processing plant is to be installed in [Hillhead Quarry] and it is this plant which would be used to process the Straitgate minerals. 
why this proposal is not premature until such time as there is sufficient processing capacity to deliver the most efficient use of this diminishing resource?
AI appears to have changed its tune, and now says that it's planning to put fixed plant at Hillhead, moving it from the site at Blackhill on Woodbury Common - shown below; or at least:
That is the plan and we are progressing capital approval to do so, after which we will seek the necessary planning permission.
Of course, whether funding or permission is forthcoming is another matter. DCC will have to determine the Straitgate application as presented to them, not on what may or may not happen in the future.



Section 106: On the question of the missing Section 106 agreement to replace private water supplies affected by any future mineral working, AI appears to have changed its tune on that too, and says:
... we will be making a commitment to replace any loss of water supply that reasonably can be associated with our activities with every expectation that DCC in consultation with the EA will wish to enshrine this in a Section 106.
Of course, the devil will be in the detail, regarding the mechanism and timeliness for determining whether failing drinking water supplies could reasonably be associated with AI’s activities.

Local water users will be mindful not only of the years it has taken to uncover the true picture of how deep AI actually intends to dig, but also of the funds and lawyers the world’s biggest cement conglomerate could deploy in the event of any dispute.

AI's been using asphalt plant without permission since 2014... and still drags its feet




The original planning permission for this plant was time-limited:
upon completion of the mineral working at the mineral site, the plant hereby approved shall be removed and the area restored ...in the interests of visual amenity.
Last May, AI submitted a planning application to retain the plant. In February of this year, DCC advised:
the deadline date for the determination of this application has been extended to the 7th March 2017 in order to allow further discussions and consideration of biodiversity off setting which may be required as a result of the land occupied by the asphalt plant not being restored for the benefit of nature conservation, as originally envisaged
AI is still dragging its feet on this, and DCC has now arranged another extension:
a further extension to September 29th 2017 [has been agreed] as the planning agent is still awaiting an ecologist report from AI
But why should the area not be "restored... in the interests of visual amenity"? 

Production of the sand and gravel feedstock for this asphalt plant is no longer carried out at Rockbeare. In fact, for the foreseeable future, aggregate feedstock for this plant will be produced at least 23 miles away up the M5.

Monday, 3 July 2017

Seasonal working scheme for Straitgate can't work as AI describes

Aggregate Industries says that any "excavation [to the Maximum Winter Water Table at Straitgate Farm] will always have at least 1.0m of unsaturated gravels beneath".

For large areas of the site, however, this is impossible.

It throws yet another question mark over AI's plans for Straitgate. The company's Head of Geological Services will apparently refer back to water consultants Amec Foster Wheeler, after the matter was pointed out to him at a meeting last week.

Just to recap, AI’s seasonal working scheme, unlike other local quarry schemes that leave 1m unquarried above the MWWT where groundwater receptors are at risk, relies on groundwater levels falling by at least 1m during the summer months to allow extraction down to the MWWT; DCC wanted to know if such a scheme had even been tried before. AI's Supporting Statement explained:
The resource declared assumes a working base that coincides with, and never drops below the Maximum Winter Water Table (MWWT) modelled by hydrogeological specialists AMEC Foster Wheeler following extensive monitoring and analysis since January 2013. Moreover, the working method ensures that the floor of the excavation will always have at least 1.0m of unsaturated gravels beneath. 2.4.7 
But such a working method could ensure no such thing.

Firstly, the MWWT was derived from just a handful of 'maximum' water levels, which may or may not actually be maximums. As Dr Helen Rutter said in her report:
This surface is only a model of reality, and may not represent actual groundwater levels across the site...
The steep hydraulic gradient combined with limited monitoring, in my opinion, is likely to result in errors in the actual depth to maximum groundwater across the site.
The accuracy of the maximum winter water level grid may benefit from additional piezometers...
It will, however, be 12 months or more before any useful information can be drawn from these.

But, crucially, groundwater levels at three of the older piezometers do not fall by 1m over the year. In fact, the difference between the maximum and minimum values over the various years of monitoring is just 24cm for PZ01, 42cm for PZ05 and 40cm for PZ2016/001. It is therefore impossible for quarrying down to the MWWT in these areas to "always have at least 1.0m of unsaturated gravels beneath".

Again, this point was picked up by Dr Helen Rutter, who said:
Groundwater levels may fluctuate by less than a metre across the intended deepening area, raising questions as to the practicality of the proposal in terms of maintaining a one metre separation between excavation and the water table.
All of this obviously affects the amount of resource available. 

AI produced a document for last year's Minerals Plan Examination - XD28 Straitgate Farm Resource Statement May 2016 - to convince the Planning Inspector that the company really could lay its hand on 1.2 million tonnes. It again claimed:

The resource declared assumes a working base that coincides with, and never drops below the maximum recorded winter water table... these levels will only be progressed during summer months when the water table is at least 1m below the said modelled surface thus maintaining a minimum 1m buffer zone.
But the Inspector was misled. The document boasted that "Calculations have been undertaken by Chartered Geologists", and yet a 1m buffer zone could obviously not be maintained "below the said modelled surface".

AI would therefore be unable to extract 1.2 million tonnes, even by using this unorthodox scheme. PZ05 and PZ2016/001 are towards the middle of the site - shown on the map below. Losing say 60cm depth of resource across 25ha would equate to some 240,000 tonnes (0.6m x 25ha x 10,000m x 2/m3 less 20% waste) - reducing the size of any benefit that must be balanced against the proposal's considerable harm.

Of course, it may be that AI knew this this all along, and had no intention to "always have at least 1.0m of unsaturated gravels beneath" where it quarried. After all, who else would know?

Who else would know - until drinking water supplies became impaired or properties became flooded?

Plans to install piezometers at Penslade

Last year, an Aggregate Industries spokesman confidently told the Venn Ottery Quarry Liaison Meeting:
Can the applicant inform the MPA regarding the likely timescale for developing the Penslade resource? 8.3
something's obviously changed.

Indeed, at a meeting last week, AI's Head of Geological Services confirmed that budgets are now in place to install piezometers at Penslade - the other Preferred Area for sand and gravel in DCC’s newly adopted Minerals Plan.

At least 12 months of groundwater data would be needed before any planning application. The site is identified as having up to 8 million tonnes of resource, and is 23 miles closer to where AI wants to process Straitgate Farm material.