New borehole readings put base of planned quarry at Straitgate 1M BELOW WATER

Aggregate Industries faces more water trouble at Straitgate Farm, and potentially further delays.

Not only does the Environment Agency want further information from the company - see post below - but new boreholes drilled last year show that AI’s model of the maximum winter water table (MWWT) has failed before any quarrying has even started.

So much for all those assurances. In the latest Hydrogeological Assessment - the one that got whitewashed - AI’s consultants promised that:

Groundwater levels would be lower than this elevation for the vast majority of the time, with this level only being reached in extremely wet conditions. 4.2.17

Monitoring over the exceptionally wet winters of 2013 and 2014 allow this surface to be defined with confidence. 6.2.2


More recently, after the EA’s objection, the same consultants again pushed the idea that the MWWT:

builds in a conservatism 2.2.2

But it does no such thing. We’ve had a relatively dry few months in the South West. The most recent groundwater monitoring data for Straitgate Farm, up to and including 8 February 2018, confirms this:

In their objection last year, the EA advised AI:

The accuracy of the maximum winter water level grid may benefit from additional piezometers

A number of additional boreholes were duly drilled - see the 2017 locations on the map below.

The monitoring data from these boreholes show the groundwater level at PZ2017/02 and PZ2017/03 to have recently reached 134.62m and 138.06m respectively.

However, the MWWT at PZ2017/02 and PZ2017/03 has been modelled to 135m and 137m respectively.

In other words, the estimated - because that’s all it is - MWWT level around these points - the level that AI proposes to quarry down to - fails to even allow for normal rainfall, let alone maximum events.

In fact, the MWWT at PZ2017/03 has been modelled ONE METRE BELOW current levels.

PZ2017/03 is at the location of "Test Hole 4". Last year we posted about "Test Hole 4"; about how AI’s own report talked about "the closeness of the water table to ground level in this area". Borehole levels now confirm this - and expose the flaws in the troubled MWWT model; it was only last year that we posted about problems elsewhere too: that AI’s seasonal working scheme can't work as described.

So, what would these 2017 piezometers be telling us if the rainfall was as high as it was during the winter of 2013/14, which was 182% of the 1981-2010 average? How far below water would the MWWT guesstimate be then?

As the EA warned earlier this month - these events are happening with increasing regularity:

Met Office records show that since 1910 there have been 17 record breaking rainfall months or seasons – with 9 of them since 2000.

We’ve warned about all this numerous times before; click on the groundwater label.

The MWWT 'surface' - the base of the proposed quarry - was modelled from just 6 'maximum' water level points across the site. We’ve argued for a long time that this surface cannot be accurate. AI’s consultants have so far refused to confirm the level of accuracy (in +/- m) for this surface - see post below. This issue is especially important given the number of local people and businesses relying on the area for their drinking water and given that AI’s unorthodox seasonal scheme does not propose to leave a 1m buffer of unquarried material above the maximum water table to protect these supplies - the typical minimum requirement elsewhere where such supplies are at risk.

The base of any quarry as proposed is obviously too low, and allows nothing for a margin of safety.

There’s been a post on the right hand side of this blog for some time: The importance of leaving 1 metre...; it’s as relevant now as when it was written in 2015:

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.

EA requests further information – again

If Aggregate Industries thought it had the hydrogeology part of its planning application to quarry Straitgate Farm finally sown up it will be disappointed; the Environment Agency wants more answers.

Last October, the EA requested further information on a number of issues - one of which was:

A description of the tolerance levels and interpolation method used to produce the ‘Maximum Winter Water Table’ grid.

Whilst AI’s consultants were happy to talk about interpolation methods, they refused to tell the EA about tolerance levels. It was the same story two years ago, when we first asked DCC - who in turn asked AI, but never got an answer to - the question:

Since AI now intends to dig right down to the maximum water table, perhaps you could ask Amec to confirm the specific level of accuracy (in +/- m) to which their maximum groundwater contours are mapped?

Why is this question important? In the same post we wrote:

The MWWT is the surface that AI wants to quarry down to at Straitgate Farm. It would be the floor to any quarry. As AI does not intend to leave 1m unquarried above the MWWT to protect drinking water supplies - the typical requirement elsewhere - it is quite appropriate to ask what level of confidence AI or its consultants Amec have in this surface, and how this tolerance level has been derived. When essentially only 6 data points have been used to model this surface across almost 60 acres, the MWWT obviously cannot be exact. So, is it +/-1m, +/-2m or more? It's important to know because it could have a dramatic bearing on any working method employed.

It’s obviously not a question that AI or its consultants want to answer. But you only have to read the post above to see how inaccurate the MWWT model is already proving.

Last week the EA requested the information again, writing to DCC:

Straitgate Action Group has highlighted to us the incompleteness of the response provided by Aggregate Industries (via AMEC) to our letter of [9 October 2017] with regard to them providing a ‘description of tolerance levels’.

Section 2.1 of AMEC’s response makes no reference to tolerance levels, the relevance of tolerance levels, or the level of accuracy in the interpolated maximum winter water table (MWWT).

We recommend that a description of tolerance levels is therefore requested again from the applicant to support the planning application and to provide clarity in advance of the Planning Committee.

The EA also used the opportunity to raise this point:

We would also like to seek additional clarification on the infiltration tests carried out on the proposed backfill material. The report, ‘Aggregate Industries UK Ltd, Straitgate Farm hydrogeological assessment’ – AFW, December 2016, states that infiltration trials have shown the disturbed, proposed backfill material to have a similar infiltration capacity to the in-situ BSPB. However, the report, ‘Aggregate Industries UK Ltd, Straitgate Farm hydrogeology/drainage – Regulation 22 responses’, AFW, July 2017, Table 2.2, shows the disturbed overburden material to have a ‘much enhanced infiltration rate’. The applicant should clarify how the infiltration rate of the proposed backfill material compares to that of the in-situ material, and what effect the change between in-situ and disturbed overburden material might have on groundwater levels beneath the site.

Has Amec (Amec Foster Wheeler, AFW, now Wood) been found out? Telling one story to one party and a different story to a different party? The answer in 2016 was provided to satisfy concerns of the EA (4.1.3); the one in 2017 to satisfy concerns of the Lead Local Flood Authority after its objection (2.10).

AI’s unorthodox scheme proposes that the quarry base would be:

backfilled with at least a minimum of 1m of material derived from the upper uneconomic BSPB, in order to create an infiltration layer 4.1.3

Anyone worried that the future hydrological landscape for drinking water, wetland habitats in ancient woodland, or flooding in this part of the Budleigh Salterton Pebble Beds would be irreparably changed - as a result of undisturbed in-situ BSPB being replaced with backfilled and disturbed overburden material - is unlikely to find comfort in Table 2.2, the table referred to by the EA in the point above.

Because much enhanced infiltration rates might not only affect groundwater levels, as alluded to by the EA, but also the speed at which future pollutants - from farming or whatever - would reach drinking water supplies. As Dr Rutter's report made clear:

the restored soil (and possibly overburden) will not have the same structure as the original, and will have less capacity to attenuate any contaminants infiltrating from the surface

Plainly AI and its consultants have some explaining to do.

SW homeowners warned ‘intense bouts of flooding to become more frequent’

Ottery St Mary has a long history of flood events. Straitgate Farm sits on a hill above the town; four watercourses emanate from it. Removing a million tonnes of sand and gravel from this hilltop site is bound to affect the hydrology and surrounding flood risk. Local people have warned DCC, and so have we; click on the flooding label.

Aggregate Industries’ consultants have previously made their own warnings too:

In removing a proportion of the unsaturated zone including the soil layer there will be a reduction in the storage capacity/buffering and so recharge may move more quickly through the unsaturated zone. The extent to which this makes the groundwater hydrograph more "flashier" would be difficult to quantify with a high degree of certainty… Within the proposed development the establishment of a 1m freeboard over and above the highest known water level provides for this eventuality. 3

Unfortunately, and as we wrote last year:

AI’s unorthodox seasonal working scheme does NOT propose to leave "a 1m freeboard over and above the highest known water level". Obviously we can now assume, by inference, that a flashier groundwater hydrograph has NOT been provided for.

Homeowners in the South West are being warned that intense bouts of flooding are set to become more frequent. The Environment Agency launched a Flood Action Campaign last week. EA chief executive Sir James Bevan warned:

Climate change is likely to mean more frequent and intense flooding.

Floods destroy – lives, livelihoods, and property. Our flood defences reduce the risk of flooding, and our flood warnings help keep communities safe when it threatens.

But we can never entirely eliminate the risk of flooding. Checking your flood risk is the first step to protecting yourself, your loved ones and your home.

DCC advised last week that funding is still available to improve a community’s flood resilience.

Last year, DCC, in its role as Lead Local Flood Authority, still objected to AI’s scheme at Straitgate Farm - despite the company having had many years to get its water act together:

At this stage, we object to this planning application because we do not believe that it satisfactorily conforms to Policy MP24 (Flooding) of Devon County Council's Minerals Plan (2011-2031) which states that proposals for mineral development must not lead to an increased risk of fluvial, surface water or groundwater flooding. The applicant will therefore be required to submit additional information in order to demonstrate that all aspects of the proposed surface water drainage management system have been considered.

AI’s consultants responded:

Any catchment is at risk of flooding associated with a rare, high-magnitude event, whether a natural catchment, or a designed drainage system. These rare events exceed local infiltration/storage capacities and result in concentrated downslope runoff. The proposed infiltration areas at the Straitgate Quarry [sic] have been designed to meet national guidance on design events (1 in 100 year with climate change). However, any bunds that may act to retain water also need to be safely designed to safely pass forward flows from these rare, high-magnitude events as would happen if the rare high-magnitude event occurred over the baseline catchment. 2.18.5

Is this enough? The EA's warning last week:

...follows a pattern of severe flooding over the past 10 years linked to an increase in extreme weather events as the country’s climate changes. Met Office records show that since 1910 there have been 17 record breaking rainfall months or seasons – with 9 of them since 2000.

The threat of flooding is real and increasing – as is also demonstrated by its listing as one of the nation’s major threats.

Last year, the Met Office published new innovative research which found that for England and Wales there is a 1 in 3 chance of a new monthly rainfall record in at least one region each winter.

UK bird strikes rise by a third in 5 years, reports CAA

The Jersey Evening Post reports "geese culled to reduce bird-strike risk to planes" and says:

According to a CAA report, between 2012 and 2016 the number of confirmed bird strikes in the UK rose from 1,380 to 1,835. The number of near misses also increased from 157 to 268.

Is it any wonder - if Exeter AIrport’s response to Aggregate Industries’ planning application to quarry Straitgate Farm is anything to go by? Exeter Airport has not objected to the ponding and wet grasslands that would attract birds and be left in perpetuity less than 200m directly below its landing approach.

Flybe operates out of Exeter Airport. In 2014, a Flybe plane taking off from Guernsey Airport collided with a bird - and was left to fly on with just one engine. Flybe has been involved in a number of other birdstrike incidents, including an emergency situation at Cardiff Airport in September.

In relation to Straitgate Farm, Matt Roach, Managing Director of Exeter Airport, wrote in December:

We are satisfied that the proposal which includes the site wildlife hazard management plan addresses the habitat for the life of the scheme and in the aftercare period (i.e. back to agricultural land) once the quarrying operation is complete. For the avoidance of doubt, one of our conditions was that the site will not have any new permanent bodies of water and furthermore we have corresponded with DCC in relation to this matter. The responsibility for bird management on the site remains with the site operator (not the airport) who must adhere to any conditions imposed. Having taken specialist advice Exeter Airport has no safeguarding concerns provided that the conditions they have submitted are agreed to and implemented. However, if the planning authority approves the application without including the conditions requested by the airport, then the airport has the right to engage the CAA to request that the application be called-in for determination by the Secretary of State.

I agree that aviation safety is paramount and Exeter Airport’s requested conditions are intended to minimise the potential impact from birds.

Exeter Airport is clinging on to the expectation that Straitgate would be left with no new permanent bodies of water - but nearby Venn Ottery Quarry was meant to be worked dry too and see how that turned out.

And on the subject of geese, this was AI’s other nearby quarry last year.

What is AI’s bottom line, because it surely can’t be profit?

Not long ago we posted that if Aggregate Industries’ resource at Straitgate Farm was equivalent to cows, it would be left with just 2 - having started with 33. Thank goodness AI leaves the farming to others.

Back in 2015 we wrote Straitgate has already been a disaster for AI. Now, AI is left with just 6% of the figure first estimated in the 1960s, and plans to extract sand and gravel from just 6 fields - but still decimating a successful dairy farm in the process.

Let's see what that shrinkage looks like in visual terms. This was the plan in 1967:

This is how the plans have changed over recent years:

And this is where we stand in 2018:

So, what is AI’s bottom line? Because it surely can’t be profit. Even if AI won planning permission - after extensive application costs - it would still have to stump up further big slugs of money:

Extensive Roman and Iron Age archaeological investigations;
Birdcage Lane 'improvements', including a bus stop for children waiting for school transport, and pedestrian provision;

Fit-for-purpose farm tracks and gates across the site around quarry workings;

Further tree planting;

Moving power lines across the site;

Cost of a 46 mile round trip for each load of as-dug material;

Provisions for mishaps / loss of water supplies to 100 people and businesses / under-recovery or over-estimation of material etc.

And all this over and above the standard outgoings for site access, tarmac haul road, wheel wash, bunding, soil mounds, restoration earth works etc.

Anyone would think AI was prospecting for gold, not sand and gravel. Or is it only concerned with what it could sell the site for afterwards? An industrial estate perhaps - if Blackhill (below) is anything to go by?