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

AI’s planning permission for the livestock crossing has expired – so what next?

Remember all the fuss about the cattle crossing – first raised here in 2017, and mentioned numerous times since?

 

The subject of the crossing was covered at the Public Inquiry, and the Planning Inspectors subsequently ruled that mineral extraction at Straitgate Farm is contingent upon the implementation of planning permission 20/2542/FUL, a permission secured by Aggregate Industries from East Devon District Council in 2021, for a "New access to the B3174 Exeter Road to provide a livestock crossing incorporating holding pens." 

Condition 19 of Aggregate Industries' permission to quarry Straitgate says: 

No soil stripping in Phase 1 of the development hereby approved shall be undertaken unless the cattle crossing permitted by East Devon District Council permission ref. 20/2542/FUL has been fully implemented and brought into operation in accordance with the conditions of that permission.

The Inspectors granting permission for the quarry spelt out the reason for this: 

109. Material to this appeal proposal is a planning permission granted by East Devon District Council (EDDC) for a new access to the B3174 Exeter Road to provide a livestock crossing incorporating holding pens. At the time of the Inquiry this permission had not been implemented. However, no cogent evidence was presented to suggest that it would not be implemented. From the details of this permission submitted to the Inquiry it is clear that this livestock crossing arrangement will enable a more direct, efficient and therefore safe movement of livestock when they need to cross the road which is of benefit to the livestock, farmer and other highway users. 

However, as we posted last year, Aggregate Industries mucked up. Permission 20/2542/FUL could not be implemented as it stood because some nitwit from the company had put the red-line planning boundary in the wrong location, as the District Council later confirmed: 

I have written to Aggregate Industries drawing their attention to this issue and recommending that they address this issue through a further application. 

Overlooking that inconvenient detail, the livestock crossing permission, granted on 21 June 2021, was itself subject to conditions, the first of which said : 

1. The development hereby permitted shall be begun before the expiration of three years from the date of this permission and shall be carried out as approved. (Reason - To comply with section 91 of the Town and Country Planning Act 1990 as amended by Section 51 of the Planning and Compulsory Purchase Act 2004). 

Today, three years have passed. 

A further application has not been made. The development has not been implemented. Parroting a famous sketch: The application is no more. It has ceased to be. It has expired and gone to meet its maker. It is an ex-application.

But that’s not the end of the story. In desperation, Aggregate Industries will now lower itself to more brutal tactics. To negate the need for the livestock crossing, and hopefully thereby to persuade Devon County Council to drop the Inspectors’ condition, the company’s ability to implement its permission to quarry Straitgate Farm will now be contingent upon foisting more pain and suffering on local people. The company will attempt to evict the tenant farmers and their children from their home – a home that has been in the same family more than 80 years – and to close down their successful dairy operation. 

The words heartless and bastards might spring to mind. 

But fortunately, and as the company itself acknowledged many years ago, the tenants have "the benefit of an Agricultural Holdings Act 1986 Tenancy Agreement." 

tenancies under the 1986 Act continue to exist because they are difficult to terminate, and because tenants have powerful rights of succession, allowing their close relatives to succeed them. 

What pain and suffering would befall this multinational cement bully should any eviction not be successful and implementation of the permission not be possible? Is there an urgent need for sand and gravel from Straitgate? Are the minerals in fact needed at all, given the millions of tonnes of similar material available to the company next to its processing plant at Hillhead also allocated in the Devon Minerals Plan? Answers: Insignificant, no and no. 

To prove the point, earlier this year, the company admitted that economic conditions are not currently conducive to the viability of mineral working at Straitgate, and that once the permission is implemented the site could be mothballed.

Tungsten West wins permit for Mineral Processing Facility, but loses CEO

Following on from a public consultation exercise, Tungsten West, the operator of the Hemerdon tin and tungsten mine near Plympton in Devon, has today announced it has been granted a permit to operate its Mineral Processing Facility – the source of complaints by local people last time the mine was operational – "within the limits previously agreed between the Company and the Environment Agency": 

This is the last of the key permits required to further progress the Project. 

However, earlier this month, it was also announced that the company’s CEO has resigned "with immediate effect". 

Tungsten West’s plans to increase sales and HGV movements of secondary aggregates were approved by Devon County Council earlier this year.

Tungsten West has received the final permit for the Mine Processing Facility. This momentous achievement is a key milestone for our company, completing the suite of permits needed to process tungsten, tin, and aggregates.
A huge thank you to all team members, past and present🙌

— Tungsten West Plc. (@TungstenWest) June 12, 2024

Aggregate Industries – planning application vs reality

Should a planning application from Aggregate Industries be read more like a sales pitch than a promise? More like a dream than reality?

Take Aggregate Industries' plans for restoring the orchard at Straitgate Farm back to "its former glory": 

3.8.14 Immediately to the south of Straitgate farmhouse is a dilapidated orchard. The orchard is shown on Ordnance Survey Maps dating back to the late 19th century and could be considered as an important part of the setting of the grade II listed farmhouse. 

3.8.15 The Applicant recognises the value of the orchard both to biodiversity and to the heritage asset and proposes to restore the orchard to its former glory by propagation from existing apple trees, growing them on and replanting in a grid pattern. Cuttings will ensure local providence and the restored orchard will provide an attractive feature.  

The orchard even featured in Aggregate Industries' error-laden Greenhouse Gas Assessment. As we previously posted, this greenwashing document told us that the "17,200m2 of restored orchard" would be planted "at a density of 2,250 trees/Ha" – a staggering 3,870 trees that would supposedly sequester an impossible "9.3 tCO2e" annually. Bonkers. 

Restoration of this orchard would, Aggregate Industries claimed in its application, involve the following:

2.6 A specialist local nursery will be engaged to graft new trees for the orchard. This involves taking cutting of scion wood from trees in the orchard and grafting them onto the stems of suitable rootstock grown at the nursery. This new grafted tree can be grown on in a pot for 2 – 3 years before being planted out in the orchard. This method guarantees the new tree will produce fruit of exactly the same variety as the tree from which it was pruned. Cuttings will be taken from 10 trees as agreed with the nursery. When grafted trees are ready, they will be planted in suitable gaps around the orchard and protected from stock grazing by individual timber post and rail with stock netting shelters, 1.8m high and 1m square. 

Cuttings will be taken from 10 trees, although but it’s not altogether clear how many would actually be planted. Surely a minimum of 10?

Aggregate Industries' marvellous before and after pictures imply a significant amount more:

The Planning Inspectors, approving the company’s plans to quarry the farm, wrote: 

85. The appellant also proposes restoration of the orchard at the front of Straitgate Farmhouse. Cuttings from the existing apple trees would be propagated and planted. We saw on our visit that tree cover within the orchard is sparse compared with what it would have been historically. Because the orchard is part of the historic layout of the grounds to the farmhouse, its restoration can be given some weight in favour. 

The restoration influenced the Inspectors’ planning balance. 

154. There are also significant material considerations which weigh in favour of the proposal. These include… restoration of the orchard at Straitgate Farm. 

Aggregate Industries has now submitted its Landscape and Ecological Management Plan to Devon County Council for approval in order to satisfy Condition 7 of the permission. How many trees are proposed to be planted? 3870? 100? 10? 

5.4.2 Five new trees from this grafted stock should be planted in the nursery when they are ready. Newly planted trees should be protected by a square, post and rail tree guard with stock netting to protect the tree from sheep grazing, such as the one in the photograph below. 

Five. Isn't Aggregate Industries embarrassed by this sort of thing?

Aggregate Industries’ Straitgate update for April & May

Aggregate Industries provided the following update this week in relation to implementing its permission to quarry Straitgate Farm:  

The May update would be that we have now submitted the first batch of schemes required by condition (of which you have copies) to Devon for formal approval.  During June I also hope to be in a position to submit our water monitoring scheme and the written scheme of [archeological] investigation.

For April, the company provided this update: 

Please find attached copies of the schemes that I have submitted to Devon [County Council] today. 

The schemes referred to by Aggregate Industries include: 

Condition 7 (Landscape and Ecological Management Plan) 

Condition 20 (Travel Plan) 

Condition 22 (HVO Use) 

Condition 26 (Airport Safeguarding) 

Condition 33 (Dust and Air Quality) 

Condition 42 (Hedgerow along A30)

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.