Merry Christmas

Another year has passed, and even though Aggregate Industries won planning permission to quarry Straitgate Farm almost two years ago – after a decade-long effort – the company has still not recovered a single bucket-load of that oh-so-precious sand and gravel from the site.

Having achieved little over the last 2 years, the company has left itself much to do in the next 12 months if it is to implement the permission before it expires on 5 January 2026. 

For instance, it must: 

• have a raft of schemes to satisfy pre-commencement planning conditions approved by Devon County Council;
• evict the dairy farm tenants – whose family has farmed at Straitgate for nearly 100 years – to overcome the expired cattle crossing permission and to achieve the enhanced biodiversity net gain figures required; 
• design a workable site access scheme to fit in the narrow space between the two TPO’d oak trees and the third party hedgebank; 
• design a surface water management plan – based on a series of yet-to-be-performed and results-far-from-certain infiltrometer drainage tests – that will not risk creating any prohibited-by-planning-conditions bodies of water, noting how problematical surface water management is currently proving for the company at Hillhead; 
• drill 4 new boreholes, install piezometers, and complete 12 months of baseline monitoring from them; 
• correct some of its water monitoring programme, and complete 12 months of accurate baseline monitoring; 
• and more... 

And yet – as the company made clear earlier in the year – Aggregate Industries currently has no appetite to work the site, given the economic outlook and the costly HVO-fuelled multi-million-mile haulage plan. 

During the year, however, Aggregate Industries did find the motivation to apply to quarry another 460,000 tonnes of sand and gravel – the same sort of sand and gravel that underlies Straitgate – at its Houndaller site next to its processing plant at Hillhead Quarry near Uffculme, that, according to the company, will see it through to the end of 2029: 

The current estimate completion date for extraction [at Houndaller] is end of 2029 with completion of restoration and landscaping by 2031, this is based on an average production rate of 350,000 tonnes per annum.

Although, judging by the figures, Aggregate Industries has in fact been producing sand and gravel at Hillhead over the last few years at the reduced rate of just 250,000 tonnes per annum. At that rate, Houndaller’s reserves would last another 8 years or so. 

So, no wonder Aggregate Industries doesn’t really seem that bothered with Straitgate.   

But such mineral talk is very un-Christmassy, so, to finish off the year on a lighter note, here’s a popular Christmas carol – with a Straitgate twist and themed scene to match – courtesy of the other sort of AI: 

– Verse 1 –


Dashing through the woods,


Where the oak trees proudly stand,


Dormice make their homes,


In this precious, thriving land.


But here comes a plan,


To tear it all away,


We’ll raise our voices loud and clear,


To keep destruction at bay! 

– Chorus –


Stop the quarry, save the trees,


Let the dormice play,


Drinking water’s under threat,


Don’t wash it all away! 


Stop the quarry, save our springs,


Nature’s worth the fight,


Protect this land for future dreams,


And keep our future bright! 

– Verse 2 –


The oak trees stand so tall,


With roots both deep and true,


They’ve weathered years of storms,


Don’t let them fall for you.


The dormice need their space,


The water must stay clean,


No digging here, no dusty trucks,


Let Devon stay serene! 

– Chorus –


Stop the quarry, save the trees,


Let the dormice play,


Drinking water’s under threat,


Don’t wash it all away!


Stop the quarry, save our springs,


Nature’s worth the fight,


Protect this land for future dreams,


And keep our future bright! 

– Verse 3 –

Devon’s land is rare,


A treasure we must guard,


With ancient oaks and wildlife here,


Destruction hits so hard.


The drinking water’s pure,


A gift we must defend,


No quarrying should take its toll,


This harm must have an end! 

– Chorus –


Stop the quarry, save the trees,


Let the dormice play,


Drinking water’s under threat,


Don’t wash it all away!


Stop the quarry, save our springs,


Nature’s worth the fight,


Protect our home for all to share,


And keep our future bright! 

We wish all readers a Merry Christmas and a Happy New Year.

AI’s Hillhead surface water management plan – more dodgy assumptions?

Flooding can have a devastating impact on communities. Not only can it cause damage to property and possessions, it can cause injury and death. The Met Office says we should expect an increasing frequency of extreme rain: 

…research, published in Nature Communications, found that under a high emissions scenario (RCP 8.5) rainfall events in the UK exceeding 20mm/hr could be four times as frequent by 2080 compared to the 1980s.

Managing flood risk is therefore an important business. Council’s trust consultants to get the figures right. 

Last month, Aggregate Industries submitted further information to Devon County Council in relation to its planning application DCC/4399/2024 for Hillhead Quarry near Uffculme, which is in part to deal with the quarry’s ponding problems.

 

In its revised surface water management plan for the site – where "all surface water will be managed in the former extraction area, with Houndaller Pond only acting as an exceedance route" – Aggregate Industries’ water consultants BCL Hydro – the same crew working on Straitgate – made a big assumption: 

The fact that [Houndaller Plantation] pond can sustain long-term and regular abstraction… means that it would be similarly effective as a soakaway.

We questioned this claim in the post AI sense-checks AI... and its soakaway assumptions at Hillhead, and wrote to Devon County Council saying: 

There remains, therefore, no cogent evidence – measurements or otherwise – of the soakaway capacity at Houndaller Plantation Pond. It is wrong to assume that Houndaller Pond would be “similarly effective as a soakaway”, and therefore it does not necessarily ‘follow’ that Houndaller Pond could cope with exceedance flows from a storm event.

But there appeared to be other wild assumptions put forward by Aggregate Industries’ water consultants too. As we set out to Devon County Council:

... it appears that the applicant’s revised plans have not allowed sufficient storage space within the extraction area for the design storm event: 

The applicant claims “the ASV [Attenuation Storage Volume] requirement equates to 3,350 m3 during the design event (1 in 100-yr + 45% allowance for storm intensity due to climate change)” and that “the revised surface water management plan for Houndaller (by incorporating 3,416.60 m3 within the former extraction area) will provide sufficient storage space for the design event.” 

The applicant claims runoff rates and attenuation requirements were computed using “the assumption that 12.75 hectares [127,500m2] of the catchment area would possess runoff characteristics analogous to that of an impermeable paved surface.” The applicant has not provided any output from those computations to substantiate the conclusions. 

An ASV of 3,350m3 divided by the impermeable catchment area of 127,500m2, implies the applicant has modelled for a rainfall event of 0.0263m or 26.3mm. 

This would seem to be an inadequate figure, given the historic records for nearby areas: 

“June 1946 In Cullompton, 2.35 in [60 mm] of rain fell in 45 minutes and ... in the lower part of the town flooding was 3 ft deep in houses.”

“22 October 1960 Flooding occurred in Crediton, following a total of 64 mm of rain on 20 and 21 October (recorded in Exeter)” 

“21 November 2012 Between 20mm to 39mm (0.8in to 1.5in) fell in 12 hours overnight on already saturated ground.” 

https://www.middevon.gov.uk/media/345917/appendix-j-historic-records-of-flooding.pdf 

The University of Exeter Weather Observation Records has the Highest Daily Rainfall at 47.20 mm on 4 September 2024.

https://empslocal.ex.ac.uk/uoeweather/records/ 

The UK’s wettest day, in records back to 1891, was 3 October 2020. The average rainfall across the entire UK was calculated at 31.7mm. The Met Office says record-breaking rainfall like that seen on 3 October 2020 could be 10 times more likely by 2100.

https://www.metoffice.gov.uk/about-us/news-and-media/media-centre/weather-and-climate-news/2021/record- breaking-rainfall-more-likely-due-to-climate-change 

Using the FEH22 rainfall depth-duration-frequency model for that area, 26.3mm is less than a 1-hour, 30-year event; by contrast, a 12-hour, 100-year event would exceed 90mm.

https://www.ceh.ac.uk/sites/default/files/2023-05/FEH22_rainfall_depth-duration_frequency_%28DDF%29_model.pdf 

A 90mm rainfall event, with the same impermeable catchment area of 127,500m2, would require a much larger storage capacity of 11,475m3...

When it came to Straitgate Farm, consultants Amec Foster Wheeler, writing Aggregate Industries’ Flood Risk Assessment, modelled for a lesser 1 in 100-yr storm event + 10% climate change, and reckoned that across the 25.61ha (256,100m2) site, a total volume of 19,054m3 was required to attenuate runoff. Dividing the latter by the former implies a 74.4mm rain event was modelled for, or 67.6mm excluding the 10% climate change uplift. Assuming Hillhead, 23 miles away, is prone to the same level of storms as Straitgate, then adding back a +45% climate change allowance, means that the surface water management plan for Hillhead needs to accommodate runoff from a 98mm storm event – or in old money, nearly 4 inches of rain. 

So why BCL Hydro has only modelled for a not-uncommon 1-inch rain event is anybody’s guess. 

Given that there are now a series of questionable conclusions from BCL Hydro – here, here and here – local people would be forgiven for having little faith in whatever surface water management plan eventually emerges for Straitgate Farm.

EDIT 17.1.25 Devon County Council issues Planning Permission for DCC/4399/2024 with conditions 

Officer Delegated Report

AI sense-checks AI... and its soakaway assumptions at Hillhead

In August this year, the Ministry of Housing, Communities and Local Government posted a blog titled Exploring the use of artificial intelligence to streamline the planning process:

Planning documents often contain vast amounts of valuable information, but accessing and using this data can be challenging. Artificial intelligence (AI) offers a potentially promising solution by efficiently processing and interrogating large volumes of data to extract key information and insights.  

Draft minutes of the October 2024 meeting of the South West Aggregates Working Party – a group referred to in this post – also talked about the use of artificial intelligence in the planning process, particularly in the analysis of consultation responses: 

EIW, LM and TB had recently attended a POS [Planning Officers Society] meeting. Various matters had been discussed including safeguarding, the Finch case (and adopting a cautious approach) and the use of artificial intelligence (AI) in the planning process, particularly in the analysis of consultation responses.

But artificial intelligence can work both ways, not only saving planning officers time in the analysis of hundreds or thousands of consultation responses, but also allowing Joe Public to sense-check consultants’ reports. 

Aggregate Industries has this month submitted further information to Devon County Council in relation to its planning application for Hillhead Quarry near Uffculme – DCC/4399/2024:

Variation of conditions 2, 4, 6, 7, 12, 19, 22 and 25 of ROMP permission DCC/3655/2014... to vary the phasing; landform; drainage; and restoration of the site. 

We had posted about this application earlier this year – here and here – which in part is to deal with the ponding problem at the quarry, and in part to deal with unsafe quarry faces – which would, fortuitously for the company, yield a further 460,000 tonnes of sand and gravel in the process. 

In June, we wrote to Devon County Council saying: 

We are concerned that the ES Chapter 9 Hydrological & Hydrogeological Impact Assessment Version 2 May 2024 for the above application is incorrect, more specifically that the calculated soakaway rate at Houndaller Plantation Pond of 5,000 m3/d is impossibly large. 

The soakaway rate being pushed by Aggregate Industries and its consultants – five thousand cubic metres per day, equivalent to 1.8 million cubic metres per year – was used to conclude that: 

5.8.8.7 ...Houndaller Plantation Pond has sufficient soakaway capacity for the design storm.

We pointed to a flaw in the author’s calculations, suggesting that the above assumption was incorrect. Devon County Council’s Flood Risk team objected to the application, and also asked for "Calculations for the current outflows from Houndaller Pond (abstraction / groundwater) to be submitted." 

Aggregate Industries has now fundamentally redesigned its surface water management plans: 

Following discussions at the site meeting held on 4th July 2024, an updated surface water management scheme has been prepared where, following mineral extraction operations, all surface water will be managed in the former extraction area, with Houndaller Pond only acting as an exceedance route.

Consultants have also had a stab at "Calculations for the Current Outflows from Houndaller Pond": 

AIUK abstracts water from the groundwater-fed Houndaller Pond in accordance with Abstraction Licence No. SW/045/0002/055. 

The quarry operator has confirmed that they make full use of this licence. The rate of abstraction is set at 14 l/s, equating to 50 m3/hr. The annual rate of abstraction comes to 180,000 m3/year. 

This abstraction activity is a sustained process, occurring day after day, and the average groundwater level contours (Figure 5 in BCL’s report) are only c.1 m below the maximum levels (Figure 6), showing that abstraction (drawdown) impacts on water level in the pond are relatively limited. 

The fact that the pond can sustain long-term and regular abstraction at 14 l/s means that it would be similarly effective as a soakaway. It follows that occasional input to Houndaller Pond as a result of storm runoff would not be expected to raise the long-term water level in the pond.

So Aggregate Industries' consultants now appear to have moved from a soakaway rate of 1.8 million cubic metres per year to one approximating just 10% of that. However, even that is a leap. 

Look at this claim again: 

The fact that the pond can sustain long-term and regular abstraction… means that it would be similarly effective as a soakaway. 

Is it correct? similarly effective? 

We asked Google’s artificial intelligence chatbot Gemini to assess the above paragraph for accuracy. One of the Points Needing Clarification or Improvement was: 

* "Similarly Effective as a Soakaway": 

While the pond can sustain the current abstraction rate, it's not necessarily directly comparable to a soakaway. A soakaway is designed to absorb and disperse water into the surrounding soil, while a pond primarily stores water. 

Could Gemini be hallucinating? 

We asked OpenAI’s ChatGPT instead: If a groundwater-fed pond can sustain long-term and regular abstraction would it be similarly effective as a soakaway? 

If a groundwater-fed pond can sustain long-term, regular abstraction, it could theoretically serve some functions similar to a soakaway, but there are important differences in design, function, and environmental impact to consider. 

* Soakaway: A soakaway is designed specifically to manage surface runoff, allowing water to percolate directly into the ground and recharge the groundwater at a controlled rate. It's typically used in areas where rainwater needs to be quickly drained to avoid surface flooding. 

* Pond: A groundwater-fed pond typically has a different purpose, such as wildlife habitat, aesthetics, or water storage. While it may lose some water through infiltration, its primary function isn’t to allow for rapid or direct infiltration into the subsurface layers like a soakaway…. etc etc 

It all sounds like common sense, but just to be sure, we also asked a human hydrogeology expert whether the pond would be similarly effective as a soakaway. He said: 

Not true. No. No. No. 

He explained that it is normally many times harder to get water into the ground than it is to take it out. 

So what are Aggregate Industries’ hydrogeologists playing at? A simple error? A wild assumption? Or just trying to hoodwink the council? 

The hydrogeologists working on the ponding problems at Hillhead, are the same ones working to implement Aggregate Industries’ permission to quarry Straitgate Farm, who will calculate infiltration rates and produce a surface water management plan for the site, a site that sits above flood-prone Ottery St Mary. It’s important they know their stuff, and worrying if they don’t.

AI’s ponding problem at Hillhead – enough water to fill 15 Olympic pools!

Any quarry Aggregate Industries ends up digging at Straitgate Farm must not introduce water bodies, because of aircraft safeguarding considerations at Exeter Airport: 

25. No water body shall be created within the site other than the approved weigh bridge lagoon.    

But Aggregate industries is not very good at controlling surface water. 

If it were, it would not be suffering a "surface water ponding issue" at its Hillhead Quarry near Uffculme. We’ve already posted about this – here, here, here and here. 

Aggregate Industries has recently lodged a planning application with Devon County Council for Hillhead Quarry near Uffculme – DCC/4399/2024:

Variation of conditions 2, 4, 6, 7, 12, 19, 22 and 25 of ROMP permission DCC/3655/2014... to vary the phasing; landform; drainage; and restoration of the site.

The Planning Statement for the application reads:  

3.4.1 Houndaller Extension Area is currently facing surface water ponding issues in Phase 6 which is preventing completion of restoration of this section of the quarry. It is considered that a similar situation will occur once extraction operations cease in Phase 7. During 2023 and to date in 2024, in excess of 1m dept [sic] of water has collected over much of the Phase 6 area. The consented final restoration landform does not allow for effective drainage. Therefore, Aggregate Industries are proposing a long-term solution for surface water ponding issues on site.  

Just how wrong has Aggregate industries got things at Hillhead? 

There may be in excess of 1m depth of water, but how far does that water extend? Fortunately, Google Earth has recently provided new imagery for the area – and the answer is 9.27 acres or 3.75 ha, giving a volume of water in excess of 37,500 cubic metres, or enough to fill 15 Olympic-sized swimming pools. 

Where is all this water to go, now and in the future? According to the Hydrological & Hydrogeological Impact Assessment for the above application: 

5.8.8.1 ... ingress waters (rainfall runoff and groundwater seepage) will be captured by the perimeter drainage ditch and directed into Houndaller Plantation Pond, which will recharge the groundwater system in the BSP Aquifer. 

5.8.8.2 An infiltration rate of 50 m/d has been used in the calculations, which is the worst-case value for hydraulic conductivity derived from falling head tests (as used for calculating the worst-case ingress rates in the extraction area). 

5.8.8.3 The design storm would raise the water level (injection head) in the pond by 0.5 m.

5.8.8.4 The mean surface area (through which the outflow occurs in the recharge / soakaway feature) is taken to be the sides of the pond when accommodating 0.5 m change in water level. 

5.8.8.5 The unlined flanks of the pond have a total length of 400 m and have an effective depth of 0.5 m; therefore, the total surface area for infiltration would be 200 m2. 

5.8.8.6 Based on Darcy’s Law, applying an injection head of 0.5 m and an infiltration rate of 50 m/d, and with the mean surface area for infiltration set at 200 m2, the soakaway rate (recharging the BSP Aquifer) equates to 5,000 m3/d. 

5.8.8.7 This is equivalent to circa 150% of the storm ingress ASV indicated at section 5.8.7.14. Therefore, it is concluded that Houndaller Plantation Pond has sufficient soakaway capacity for the design storm. 

However, this calculation doesn’t look right: a soakaway rate of 5000 cubic metres of water per day through an infiltration area of just 200 square metres seems impossibly large.

What do we find? Firstly, the author of the report has not assumed "the worst-case value for hydraulic conductivity" they have in fact assumed the best: 

3.5.9.1 The hydraulic conductivity of the BSP has been determined from falling head tests undertaken in the area; and typically varies between 5.8x10-4 and 7.3x10-6 m/s, equivalent to 0.6-50 m/d. 

Secondly, the author has omitted the length of the flow path (l) from their calculations. Darcy’s Law relates the flow of groundwater through the saturated aquifer (Q) to the cross section of the aquifer (A) and the hydraulic gradient (h/l) and is written as Q = -kAh/l, where k is the hydraulic conductivity. 

Using the worst case of 0.6m/d for hydraulic conductivity (k), with 200m2 (A), 0.5m (h) and, for example, a 1000m flow path (l), the soakaway rate would fall from the incredible 5,000 m3/d to just 0.6 x 200 x 0.5/1000 = 0.06m3/day – almost 100,000 times less. 

Which means that it’s not at all clear that Houndaller Plantation Pond does have "sufficient soakaway capacity for the design storm." 

The Hydrological & Hydrogeological Impact Assessment for the above application was authored by the same team that will, either this month or next*, be trying to work out infiltration rates at Straitgate Farm. Hardly instills confidence does it?

EDIT 25.6.24 *Infiltration tests now postponed by Aggregate Industries until "end of July/early August". 

EDIT 12.7.24 Objection from Devon County Council Flood Risk Team

EDIT 2.8.24 Regulation 25 Request

Aggregate Industries had extra 460k tonnes of sand & gravel up its sleeve all along

At the Public Inquiry in October 2022, Aggregate Industries pointed to the less-than-7-year landbank for sand and gravel in Devon, and claimed there was therefore an "urgent" need for a quarry at Straitgate Farm. As a result, in weighing up the planning balance, the Planning Inspectors concluded there were: 

154. ... significant material considerations which weigh in favour of the proposal. These include its contribution to sand and gravel supply in Devon in circumstances where there is not currently a 7-year landbank as required by the Framework. 

Ten months before, in December 2021, at the time Aggregate Industries’ application to quarry the farm was refused by Devon County Council, the landbank was actually above 7 years, according to a subsequent revision by the Council. However, by the time of the Public Inquiry, the landbank had indeed dropped to 6.4 years, based on permitted reserves of sand and gravel in the County at the end of 2021 of 3.317 million tonnes, divided by the 10-year sales average of 0.514 million tonnes per annum. 

But, surprise, surprise. It now turns out that, at the time of the appeal, and unbeknown to the Planning Inspectors, Aggregate Industries had another 460,000 tonnes of sand and gravel up its sleeve, which, once permitted, would have pushed the landbank to over 7 years. 

Aggregate Industries has recently lodged a planning application with Devon County Council for Hillhead Quarry near Uffculme – DCC/4399/2024 "Variation of conditions 2, 4, 6, 7, 12, 19, 22 and 25 of ROMP permission DCC/3655/2014... to vary the phasing; landform; drainage; and restoration of the site." 

This application is concerned with modifications to the Houndaller part of the site – a site with the same sort of material that underlies Straitgate Farm – that has suffered from ponding problems, as we have posted about here, here and here.

The Planning Statement for the application reads: 

3.4.1 Houndaller Extension Area is currently facing surface water ponding issues in Phase 6 which is preventing completion of restoration of this section of the quarry. It is considered that a similar situation will occur once extraction operations cease in Phase 7. During 2023 and to date in 2024, in excess of 1m dept [sic] of water has collected over much of the Phase 6 area. The consented final restoration landform does not allow for effective drainage. Therefore, Aggregate Industries are proposing a long-term solution for surface water ponding issues on site. 

Clearly, the concern must be that if the company hasn’t been able to adequately manage surface water at Houndaller, it doesn’t stand much chance of complying with the no water bodies condition at Straitgate: 

25. No water body shall be created within the site other than the approved weigh bridge lagoon.   

However, the company’s application for Houndaller is not just concerned with surface water management. The application’s Non-Technical Summary says: 

1.1.6 The proposed modifications to mineral operations at Houndaller include removal of two unsafe historic faces which will provide an estimated 460,000 tonnes of permitted reserves to Devon’s sand and gravel landbank. 

1.4.10 In addition, at present the approved plans under the extant consent contradict each other, with the approved restoration plan (ref. 2285/ROMP/4C) not showing the ridge along the northern boundary of phase 8, but it is in-situ on the working plans (ref. 2285/ROMP/3C & 2285/ROMP/73D) thereby creating an anomaly. Therefore, at present the approved restoration scheme cannot be delivered as currently consented. 

A spare 460k tonnes? Unsafe quarry faces? Approved plans that contradict each other? How has Aggregate Industries allowed all this to happen? 

But could it be that these perilous quarry faces were not known about at the time of the 2022 appeal? Not unless Aggregate Industries has been asleep for 20 years. The application’s Planning Statement points to The Quarries Regulations of 1999 and says: 

3.2.6 It is proposed to remove the ridge escarpment which lies adjacent to the eastern edge of Houndaller Plantation Pond which is in the northern part of Houndaller Extension Area and former Phase 1 area. 

3.2.7 The former Houndaller Phase 1 extraction area, north of the current Phase 8, had been worked pre-Quarry Regulations 1999 when long-term geotechnical stability of the final quarry faces when excavating sand and gravel material was not given the consideration which is now required for quarry legislative purposes. Whilst this area is now restored, the historical faces are currently up to 20m high and 65˚ to near-vertical therefore presenting both a stability, and health and safety issue. 

3.2.8 Hillhead Quarry is now subject to a Regulation 33 geotechnical assessment every two years. Within this assessment, there are various design criteria that the quarry must use to ensure geotechnical stability for both active and inactive faces. These design criteria’s are derived from the specific geotechnical properties of the geology onsite and from various stability analyses undertaken alongside the assessment. 

3.2.9 Based on the current design criteria for restoration slopes, the historic faces adjacent to the eastern edge of Houndaller Plantation Pond and along the northern boundary of the current approved Phase 8 extraction area have been assessed and are considered to be excessively steep and too high for long- term stability. They therefore currently present a significant geo-technical risk, and health and safety hazard. The current Regulation 33 Geotechnical Assessment for the site states that "Aggregate Industries must develop a plan to include remedial actions on these historic quarry faces". Further detail on the stability issues are presented within the Stability Assessment accompanying this planning application at Appendix 6.2.

The company would therefore have known for years that these hazardous quarry faces did not comply with the 1999 regulations, and that removing them would likely yield extra material. 

But perhaps it forgot all about them at the time of the Straitgate appeal in October 2022? This isn’t likely either. The Stability Assessment referenced in Appendix 6.2 says: 

1.3 ...It was identified in 2022 that the restoration plan needed to be updated to include improved drainage and to update the final profiles in relation to the materials available for backfilling the extraction area. At this point it was a natural way to deal with this legacy face to ensure the whole Houndaller excavation area is left in an adequate way that it supports long term stability and no hazards remain when Aggregate Industries complete this area.

So, how very clever of Aggregate Industries to keep all this material – about half the quantity available at Straitgate – up its sleeve. 

Prior to the determination of its Straitgate Farm application, Aggregate Industries had been in the habit of losing material – including at Houndaller – which had the inevitable effect of reducing the landbank and creating the impression of need for Straitgate. Miraculously, after Straitgate is determined, we now discover the company has found material again. How convenient. How cunning. 

What does this application for Hillhead mean for the County’s sand and gravel supplies: 

3.2.16 The current estimate completion date for extraction [at Houndaller] is end of 2029 with completion of restoration and landscaping by 2031, this is based on an average production rate of 350,000 tonnes per annum. 

Assuming production for the years 2024,25,26,27,28,29 this implies that some 2.1 million tonnes remain, or 1.64 million tonnes excluding the newly found 460,000 tonnes. Aggregate Industries helpfully confirmed in 2019: 

The company's reserves schedule for Houndaller was subsequently revised to 2.9 million tonnes as at 1st January 2019.

Subtracting those two figures implies that over the 5 years 2019,20,21,22,23, some 1.26 million tonnes of sand and gravel has been produced, at a rate of 250,000 tonnes per annum. 

At this rate, Houndaller would in fact last another 8 years. 

Of course, this is why Aggregate Industries – knowing all along it had extra material at Hillhead – has been in no rush to advance its plans for Penslade, despite starting groundwater monitoring in 2021. 

Penslade is owned by Aggregate Industries, and again has the same type of material that underlies Straitgate. Whilst Aggregate Industries claims there is 1.06 million tonnes of saleable aggregate at Straitgate, Penslade is a 23 million tonne sand and gravel resource, 8 million of which is allocated in the Devon Minerals Plan. It sits next to the company's processing plant, not – like Straitgate – 23 miles away. At the appeal, the Council’s Mineral Planning Authority said: 

5.1.13 The Appellant has stated at meetings of the local liaison group for Hillhead Quarry that it is preparing a planning application for their West of Penslade Cross site (to the east of Hillhead Quarry), having undertaken investigative boreholes and intending to seek pre-application advice from the Council before the end of 2022, with a view to submission of an application in 2023. It is also understood that remaining reserves at Hillhead Quarry are sufficient to maintain supply until a new quarry at Penslade has been approved and is capable of being implemented. 

However, to date, no planning application for Penslade has arrived. All Aggregate Industries would say at the appeal was: 

8.4 Aside from the appeal site, the only other allocated site is West Penslade. West Penslade is also AI controlled which [sic] and would be an extension for the Hillhead quarry (planning permission ends in 2028). West Penslade will not come online until then. 

The bottom line is that Straitgate is not quite so urgent after all. 

Furthermore, as we posted last month, Aggregate Industries now says that if current market conditions persist then Straitgate will have to be "mothballed". Local people will wonder what strategic thinking goes on at Aggregate Industries, if any. 

What else does DCC/4399/2024 tell us? In relation to groundwater and nearby water users: 

5.7.3 Throughout the lifetime of the development, some 2 m thickness of unsaturated material will be retained beneath the quarry floor at the western margin of the Houndaller Extension. 

Compare and contrast that with extraction all the way down to the maximum water table at Straitgate, a site with more than 10 times the number of nearby private water supplies at risk than at Houndaller. Even so, Aggregate Industries again recognises that private supplies will be put at risk:

5.7.14 In the unlikely event that a supply is shown to have been impacted by quarry-related drawdown, the following approach is proposed to provide mitigation… The fallback position would be the provision of mains water. AIUK would cover the costs for mains water connection and usage at any property where the water supply is affected by the quarry development. 

What ecological damage will be done in removing those treacherous quarry faces? 

3.5.3 As part of the remedial works for the two unstable ridges within the northern extent of Houndaller, approximately 28,863m2 of lowland mixed deciduous woodland is required to be removed.

 

Which rather undoes this PR piece pushed out by Aggregate Industries last year, congratulating itself for planting saplings at Hillhead. 

Devon County Council is accepting comments on DCC/4399/2024 until 29/06/2024.

AI’s ponding problems at Hillhead worsen – attracting ducks & gulls too

Aggregate Industries’ plans for Straitgate Farm positively encourage the creation of water bodies – for surface water management and restoration. However, for Airport Safeguarding reasons, the Planning Inspectors only granted permission to quarry Straitgate on the condition that: 

25. No water body shall be created within the site other than the approved weigh bridge lagoon.  

As we posted a year ago: 

This condition... is clear and unambiguous. It is not limited by the size or duration of any water body – large or small, permanent or temporary.  

We have since posted We all know Aggregate Industries will have difficulty complying with Straitgate’s ‘no water body’ condition – Google Earth images confirm why. 

In June last year, we posted – here and here – about the ponding problems Aggregate Industries has suffered at Houndaller quarry at Hillhead, near Uffculme, where the company is extracting the same type of sand and gravel available at Straitgate. 

What’s the scale of the problem? Devon County Council's monitoring report for Hillhead Quarry in 2022 provided this photo:

The latest monitoring report for the site issued this week reveals that the ponding problems remain ongoing and are slowing down restoration: 

4.16 ...The water is ponding in this Phase and the operator would like to direct this water to Houndaller Pond, north of the farmhouse, in order to complete restoration. Therefore, a non-material amendment was submitted in order to alter the phasing of working. The has resulted in the operator entering the western end of Phase 8 to allow water to move from Phase 6, into Phase 7 and 8 temporarily whilst restoration is under way. Originally, working in Phase 8 was to commence at the eastern end. Alterations to allow water to enter Houndaller Pond will need to be subject to a full application. 

4.17 Despite the ponding, work has begun on restoring Phase 6 at the eastern end to the final restoration levels. It is anticipated this will be completed in 2025, however, it is understood the ponding is slowing this down... 

The report didn't say if the ponding problem had worsened. However, photos taken this week, above and below, show that it has:

Furthermore, the water is attracting ducks and gulls – the sort of species that would be particularly hazardous at Straitgate, being just 200m below the landing approach for Exeter Airport.

Even without its plans that encourage water bodies at Straitgate, Aggregate Industries’ problems at Hillhead – and the ponding at its other sand and gravel sites in Devon for that matter – demonstrate the company hasn’t a ghost of a chance of complying with condition 25 at Straitgate.

We all know Aggregate Industries will have difficulty complying with Straitgate’s ‘no water body’ condition – Google Earth images confirm why

One of the first posts on this blog, back in 2012, asked: Could Straitgate be quarried without water? 

We noted that Exeter Airport's request that "no ponds or body of water be allowed as part of this development" to ensure aircraft safety from bird strikes, would surely be an impediment to any scheme. 

And indeed this impediment has now been formalised.

Earlier this year, the Planning Inspectors, in granting permission to quarry Straitgate Farm, conditioned: 

No water body shall be created within the site other than the approved weighbridge lagoon. 

As we posted in January, this makes Aggregate Industries' plans for Straitgate incompatible with the Inspectors’ planning conditions, given that the company's approved plans rely on the formation of water bodies – both for flood mitigation and for restoration. As we wrote, the Inspectors' condition: 

...is clear and unambiguous. It is not limited by the size or duration of any water body – large or small, permanent or temporary.  

What exactly is a water body? As we previously posted: 

Wikipedia says "The term most often refers to oceans, seas, and lakes, but it includes smaller pools of water such as ponds, wetlands, or more rarely, puddles." LawInsider goes further. This helpful graphic also explains.  

In that 2012 post, we wrote about Aggregate Industries' nearby sand and gravel quarries at Blackhill and Hillhead, quarries that extracted the same type of material from the Budleigh Salterton Pebble Beds that would be extracted at Straitgate Farm. We wrote that Google Earth images: 

...reveal several bodies of water in each and it is inconceivable that Straitgate, particularly with all its water related issues, could ever be quarried without the formation of ponds or lagoons of some kind.

In fact, Hillhead suffered ponding problems only this year. 

Further back, we posted how the water body at Aggregate Industries' quarry at Thorn Tree Plantation at Blackhill was meant to be ephemeral but is instead present all year round. 

The company's quarry at Venn Ottery also suffered ponding issues. 

Hanson’s Town Farm Quarry works the same type of material and also has bodies of water. 

But let's build on that 2012 post, and, using Google Earth’s historical imaging, look at all five BSPB quarries in Devon that have been worked in recent times. The images below show the quarries at Venn Ottery, Marshbroadmoor at Rockbeare, Thorn Tree Plantation at Blackhill, Houndaller at Hillhead and Town Farm, at a time when extraction was actually underway. 

Venn Ottery

Marshbroadmoor

Thorn Tree Plantation

Houndaller

Town Farm

Clearly, sizeable new bodies of water were introduced at all of them.

So, even if we were to overlook Aggregate Industries' flood mitigation and restoration plans for Straitgate – that actually encourage water bodies – the above images underline, if any more underlining were needed, just how unworkable the whole scheme really is. 

What’s the scale of Aggregate Industries’ ponding problem at Hillhead?

If Aggregate Industries is to quarry Straitgate Farm, it must do so without creating any water bodies – for aircraft safeguarding reasons – as we have previously posted. 

Is that possible? Of course not. 

How can we be so sure? You only have to look at Aggregate Industries’ Houndaller quarry at Hillhead, near Uffculme. It has the same type of sand and gravel that exists at Straitgate Farm. We recently posted that Aggregate Industries has ponding problems at Houndaller, and that the company has now been forced to apply for permission to change the surface water management plan for the site. 

Last December, Devon County Council’s Monitoring Report for the site reported: 

4.15 Since the previous monitoring visit, Phase 6 has now been worked out and is awaiting grading and topsoiling… It is understood water is ponding in this Phase and the operator would like to direct this water to Houndaller Pond, north of the farmhouse in order to complete restoration.

 And the scale of the problem? The Monitoring Report helpfully provides this photo:

AI’s archeological analysis & report for Hillhead more than THREE YEARS LATE

Aggregate Industries finds it difficult to stick to planning conditions – as we have previously posted here, here, here, here, here, here and here. 

Condition 12 for Aggregate Industries’ Houndaller quarry at Hillhead near Uffculme in Devon states: 

RECORDING OF ARCHAEOLOGICAL AND HISTORIC FEATURES 

No topsoil stripping shall be undertaken in Working Phases 6, 7 and 8, as shown on drawings nos. 2285/ROMP/3C and 2285/ROMP/73D, until the applicant has secured the implementation of a programme of archaeological work in accordance with a written scheme of investigation which has been submitted by the applicant and approved by the Mineral Planning Authority. The development shall be carried out at all times in strict accordance with the approved scheme, or such other details as may be subsequently agreed in writing by the Mineral Planning Authority. 

Reason: To ensure that an appropriate record is made of archaeological evidence that may be affected by the development in accordance with the Development Plan specifically Devon Minerals Plan Policy M19.

Why is this condition important? 

In 2016, Devon County Council’s Senior Historic Environment Officer wrote: 

…the [geophysical] survey did identify anomalies that have the appearance of land divisions and may be associated with former prehistoric or Romano-British field systems. The expansion of the quarry into these areas will destroy these heritage assets. … 

Based on the results of this initial stage of works the requirement and scope of any further archaeological mitigation can be determined and implemented either in advance of or during construction works. This archaeological mitigation work may take the form of full area excavation in advance of groundworks or the monitoring and recording of groundworks associated with the construction of the proposed development to allow for the identification, investigation and recording of any exposed archaeological or artefactual deposits. The results of the fieldwork and any postexcavation analysis undertaken would need to be presented in an appropriately detailed and illustrated report.

The initial archaeological fieldwork was completed in 2019, so where’s the analysis and report? How do we know what’s been destroyed? Devon County Council’s latest monitoring report for the site says the report should have been "completed within 3 months following the completion of fieldwork": 

Comments/ Course of Action: 

Written Scheme of Investigation entitled ‘Western Extension of Houndaller (Hillhead) Quarry, Phases 6, 7 and 8, Uffculme, Devon - Project specification for an archaeological excavation’ dated 18th April 2019 - approved on 14 May 2019. Soil stripping on Phase 6 commenced on 12 August 2019 and archaeological investigation was complete. The archaeological investigation for Phase 7 is complete, however, post-excavation analysis, reporting and archive is yet to be completed. The agreed Written Scheme of Investigation states that this will be completed within 3 months following the completion of fieldwork. The operator has confirmed that this is anticipated to be completed within 3-4 months. Therefore, this should be completed within 4 months, by 13 July 2023.

As of last week, MORE THAN THREE YEARS LATE, Aggregate Industries has still not done the work, with the Council’s Senior Historic Environment Officer, writing: 

the post-excavation assessment, analysis, reporting and archive creation and disposition has yet to be undertaken. 

What hope, therefore, for the plethora of conditions for Straitgate Farm?

Oh look, Aggregate Industries suffers ponding problems at Hillhead

After many years of working its Houndaller quarry at Hillhead, near Uffculme, Aggregate Industries now wants to change the surface water management plan for the site – a site with the same type of sand and gravel that exists at Straitgate Farm – as this recent Scoping Opinion request PRE/1659/2023 to Devon County Council reveals: 

The approved restoration contours, Drawing No. 2285/ROMP/4C located within Appendix C, illustrates the site falling west to east, with a low point on the south-western boundary of the site. This is causing surface water to pond within the south-western part of the site (Phase 6). Therefore, Aggregate Industries are proposing to amend the surface water management plan for the site, to include a perimeter surface water drainage ditch running northwards from the south-west corner of Phase 6 along the western edge of the site into Houndaller Plantation Pond. There will be a slight amendment to the alignment of the final land form contours for Phases 6,7 and 8, to enable surface water to be shed to the perimeter surface water drainage ditch. 3.2.3 

Of course, it’s not unusual for surface water to pond at quarries. What quarry doesn’t have water? 

Even for Straitgate Farm, Aggregate Industries’ plans positively encourage water bodies – for its surface water management and restoration plans: 

ephemeral water bodies and species-rich wet grassland to be encouraged in low-lying infiltration areas (in the base of the depressions)

In fact, the creation of infiltration areas on the eastern boundary of the Straitgate site forms an integral part of the company’s flood mitigation scheme. At the Public Inquiry the Inspectors were told by Aggregate Industries’ hydrogeology witness that standing water will remain in these areas for up to 15 days in the summer and 24 days in the winter.

However, and as we have previously posted, the Planning Inspectors stipulated – for aircraft safeguarding reasons – that: 

25. No water body shall be created within the site other than the approved weigh bridge lagoon. 

Bizarrely, therefore, Aggregate Industries’ plans for Straitgate cannot be implemented without breaking one of the planning conditions. 

As we remarked: 

This condition, which Aggregate Industries must comply with if it is to quarry Straitgate Farm, is clear and unambiguous. It is not limited by the size or duration of any water body – large or small, permanent or temporary. 

The company's inability to control surface water at Houndaller, highlights the problem: How will Aggregate Industries be able to comply with condition 25 at Straitgate ?

‘No digging at Straitgate before 2025’ – says Aggregate Industries

Oh, the tales Aggregate Industries has told on its way to winning permission to quarry Straitgate Farm.

Would locals have been more sympathetic to the idea of a quarry at Straitgate if they hadn’t been spun so much fiction? Possibly not – but the company will now face a harder job if it wants to build any trust with the local community. 

Last week, Aggregate Industries’ personnel – delivering letters to local people with private water supplies now at risk – said that, because of pre-commencement conditions, work would not start at Straitgate before 2025. 

This is some 15 years after the company put Straitgate forward in a call for aggregate sites and some 57 years since the first planning application was turned down – with permission now granted for an amount just 1/8th or 1/20th of what was hoped for at those respective times. If all mineral planning applications were that successful, the industry would be on its knees. 

But who knows whether 2025 will actually be the year that bulldozers finally rip Straitgate Farm apart? 

Once upon a time, back in 2015, Aggregate Industries said that Straitgate should come on stream quickly to replace exhausted reserves at nearby Venn Ottery Quarry. The company claimed: 

1.15 AI produces sand and gravel at Venn Ottery Quarry, which currently has permitted reserves capable of providing saleable material until early 2016 based on current levels of sales (350,000 tonnes per year). It is therefore necessary to plan for additional reserves being available from early 2016. The sand and gravel reserves at Straitgate Farm are considered to be a direct replacement for reserves at Venn Ottery. 

What was wrong with the millions of tonnes of sand and gravel already with permission at Hillhead – which the company is now using? The company had another tale: 

5.7 AI also has reserves at Hillhead Quarry (the Houndaller Extraction Area) located at Uffculme in East Devon. The extraction of the Houndaller reserves as an alternative to the mineral deposit at Straitgate is not a sustainable solution by virtue of the % ratio of gravel to sand. The Houndaller deposit is made up of 75% sand: 25% gravel. To meet the needs of the county in terms of gravel production would lead to a massive over-production of sand on account of this imbalance. 

Somehow, since 2016, and now apparently not until 2025, Aggregate Industries has managed to meet the needs of the county with the reserves at Hillhead, and without the benefit of Straitgate. If anybody has seen a "massive over-production of sand" littering the Devon landscape, the Mineral Planning Authority at Devon County Council would surely like to know. 

Straitgate material will be taken 23 miles to Hillhead for processing. One assumes Aggregate Industries will have assessed the financial viability of this, but in 2015 the company claimed: 

8.27 If a processing plant were erected at Hillhead to process the Straitgate mineral, it would need to be substantially modified or reduced to be able to process the Hillhead mineral, rendering such a circumstance economically unviable. 

This in contrast with what the company claimed at the Public Inquiry: 

3.13 In contrast, the sand and gravel deposit indigenous to Hillhead Quarry is red in colour and is sand rich, containing circa 20% gravel. The two mineral deposits complement each other well and it is proposed to process the two deposits together to provide the market with the mix of products it demands. 

The "mythical yellow sand of Straitgate" was "debunked" at the Inquiry. Furthermore, the company also once claimed: 

8.36 It should also be noted that the current markets for the Venn Ottery mineral are in Exeter and East Devon. This is anticipated to apply to mineral from Straitgate. In the event of processing at Hillhead, this would result in further additional mileage being incurred to transport mineral product to the markets.

This again is contrary to what was claimed at the Public Inquiry: 

6.96 The calculations in the report show that the appeal proposal for extraction at Straitgate Farm with onward processing at Hillhead Quarry will result in 11% lower GHG emissions than meeting the demand for sand and gravel in proposed markets from existing quarries. This is mainly due to these markets being closer to Hillhead than existing suppliers.

which was in turn contrary to another previous claim: 

8.48 Processing at Hillhead may be feasible, but would generate a massively greater quantity of CO2 emissions from the additional mileage required to be travelled. 

This was a line played back to Aggregate Industries at the Inquiry, a line that – as with so many other things – the Inspectors were happy to disregard. 

So, going forward, people should be forgiven if they don’t trust everything Aggregate Industries tells them.