AI fails to answer Natural England’s BMV & subsoil concerns – and gets soil storage numbers completely wrong

We recently posted that Aggregate Industries – in its "final response" – had refused to supply cross sections to Devon County Council's Flood Risk Management Team in its role as Lead Local Flood Authority, to show how the infiltration areas intended to prevent downstream flooding could be accommodated within the extraction area. 

In the same final response, Aggregate Industries has also failed to answer Natural England's concerns on how the soils would be restored back to best and most versatile agricultural land, particularly how the two subsoil resources would be stored and restored. Soil volume numbers are also completely wrong.

The Soils Report provided by Aggregate Industries states: 

Two subsoil resources have been identified, one heavy loam and one clay. 

Subsoil S1 

4.4 Although there is some variation in texture across the site, the upper layer of subsoil is medium to heavy textured and can be considered as a single resource. It is easily damaged by mishandling and should be stripped when as dry as possible down to the easily distinguished clay or the gravel layers which are below it. The thickness of the this [sic] resource is variable, and in some localities extends below 1.2 m depth, but the mean thickness is approximately 250 mm...  

Subsoil S2 

4.5 This comprises the dense clayey or heavy clay loam lower subsoil which is a poorer resource easily damaged by mishandling. Its thickness cannot be estimated from an auger survey. 

The Soils Management Scheme document, again provided by Aggregate Industries, states:

...although the topsoil was a single unit across the application site, the subsoil was split into two types, broadly relating to the different ALC gradings: subsoil type 1 coincided with Grade 2; subsoil type 2 coincided with Grade 3b; whilst Grade 3a had both subsoil types.

All topsoil and the two subsoil (upper and lower) units will be stripped and stored separately to enable later reuse as part of final restoration. 

In its final response, Aggregate Industries says the following soil quantities would be generated: 

Grade 2 (3ha) – 9,000m3 of top soil [300mm] and 7,500m3 of sub soil [250mm] 

Grade 3a (14ha) – 42,000m3 of topsoil [300mm] and 35,000m3 of subsoil [250mm] 

Grade 3b (2ha) – 6,000m3 of topsoil [300mm] and 5,000m3 of subsoil [250mm] 

We have added the implied depth of material in brackets. 

But the numbers are nonsense. They IGNORE the topsoils that must be removed from subsoil storage areas, and they IGNORE the topsoil and subsoils that must be removed in overburden storage areas – because like must be stored on like. The Soils Management document says:  

3.3 Topsoil would be stripped in advance of subsoil mound construction and the topsoil and subsoil would be stripped in advance of overburden mound construction... 3.2 (to allow like-on-like materials to be placed on top of each other). 

How much additional soil would be generated from the storage areas? The drawing below gives a clue.

Furthermore, where are the details about subsoil S2 in Aggregate Industries' response? Subsoil S2 is found across the bulk of the site. The company's Soil Report says: 

4.9 To restore the land to agricultural best and most versatile quality will require a profile of at least 550 mm of topsoil and loamy subsoil placed over subsoil S2. 

The Soils Management Scheme report warns:

3.1 The main limitation to restoring the entire application site to best and most versatile quality will be the inherent characteristics of subsoil type 2

In May, Natural England requested information on this very subject, i.e.: 

The degree to which the best and most versatile land should be capable of being reclaimed without loss of quality. 

Without this information, Natural England may need to object to the proposal. 

Please re-consult Natural England once this information has been obtained.

 

Amongst other things, the statutory consultee wanted to know about the two subsoil resources: 

Natural England note that two subsoil resources have been identified on the site... 

The Soil Management Scheme does not make it clear that the subsoils S1 and S2 will be stripped and stored separately and the plans submitted... detailing the onsite designated areas for the temporary storage of subsoil do not show the storage location of subsoils S1 and S2... Without the separate stripping and storage of the subsoil S1 and S2, the accurate detailing of their storage location, and the restoration as described in the ES Ch 14 above it is our advice that this would [compromise] the ability to achieve high standards of restoration and to restore the land to agricultural best and most versatile quality. 

So – given Natural England requested information on subsoils S1 and S2 – where is that information? If both are needed to restore the land back to BMV, why is there no mention of the two subsoil resources in the company's final response? Why is there no mention of how these two resources would be stored?

But Aggregate Industries doesn’t just fail there. The company claims: 

In respect of the maximum extent of disturbed land open for which storage capacity is required, this has been calculated as follows: 

Ancillary area – 8ha (top and sub soil stripped only) 

Phase 1 – 6ha (top soil, sub soil and overburden stripped) 

50% of Phase 2 – 5ha (top soil, sub soil and overburden stripped)

But it is plain to anyone who reads the Soils Management document – "3.2 All of the soil resources from Phase 3 will then be direct placed into the previously worked out void, as shown in Drawing SF / 5-3 Rev B" – and who looks at that drawing "SF / 5-3 REV B", that the above is not correct. The drawing shows all the phases in operation; phase 1 would not start to be restored until the beginning of phase 3: 

SOILS FROM PHASE 3 DIRECT PLACED ONTO PHASE 1 

In conclusion, "the maximum extent of disturbed land open for which storage capacity is required" would significantly exceed the area claimed in Aggregate Industries' final response. Additional capacity would be needed to accommodate all the different soil types from the extraction, ancillary and storage areas. Where would all that capacity be found?

Six years on from first submitting this planning application, Aggregate Industries still can't seem to get its head around soil management.