Minerals Sterilisation considerations for Land Developers

For many years, since minerals planning was formalised through a Minerals Local Plan based system in the early 1980s, County Councils as mineral planning authorities have carried a general responsibility to try and avoid mineral resources - mainly bulk materials such as aggregates and clays - from being sterilised, or put beyond use, by permanent surface development. In the author's experience this responsibility was discharged fairly patchily in the distant past but following the introduction of the National Planning Policy Framework (NPPF) in 2012 many Counties are applying sterilisation policies with greater vigour.

From a construction materials mineral company point of view this is often very welcome, since some quite substantial resources have been previously sterilised, but from a house builder point of view possibly less so.

At base the proposition is that permanent surface development should not sterilise or put beyond use minerals of economic value. These tend to be mostly construction materials such as sand/gravel, hard rock, high PSV rock, limestones, building sand, clays, silica sands, or cement feedstock but potentially also iron ore, phosphate, gypsum, salt and other more rare minerals.

Typical policy wording might be similar to the examples below:

By applying Mineral Safeguarding Areas (MSAs) and/ or Mineral Consultation Areas (MCAs), the Mineral Planning Authority will safeguard mineral resources of national and local importance from surface development that would sterilise a significant economic resource or prejudice the effective working of a permitted mineral reserve, Preferred or Reserve Site allocation within the Minerals Local Plan. The Minerals Planning Authority shall be consulted, and its views taken into account, on proposed developments within MSAs and MCAs except for the excluded development identified...

Or:

Existing minerals extraction sites will be safeguarded against non-mineral development that prejudices their ability to supply minerals in the manner associated with the permitted activities.

Sand and gravel, brick-making clay, building stone resources and chalk reserves are safeguarded against sterilisation. Proposals for non-mineral development within the Minerals Safeguarded Areas will not be permitted unless:

Mineral sterilisation will not occur; or
It is appropriate and practicable to extract the mineral prior to the development taking place, having regards to the other policies in this Plan; or
The overriding need for the development outweighs the safeguarding of the mineral and it has been demonstrated that prior extraction is not practicable or environmentally feasible.

If a built development planning application is made on a land area that the Mineral Planning Authority - usually the County or a Unitary Authority - consider likely to have mineral potential they will require a Mineral Resource Assessment to accompany the application. The purpose of such assessment is to demonstrate whether there is or is not a mineral deposit of economic significance under the land surface. If such a mineral resource is likely to be present a complication immediately arises in that the developer is suddenly dealing with two authorities, typically a District Council for the main application and the County Council or Unitary Authority for the minerals if present.

Possible scenarios

A number of scenarios might exist. If investigations prove that there is no mineral present then the matter goes away and all parties have honoured their obligations. If however some mineral is identified then a number of variables and consequences come into play:-

Mineral might be present but be too thin, of poor quality, be heavily constrained by physical factors, or of insufficient size to be an economic proposition.

An economically viable resource might lend itself to prior extraction in whole or in part with subsequent built development on a new land surface at a lower level. This can be good news but it can also introduce delays in that many authorities will wish to see a separate planning application made to the mineral planning authority rather than allow the decision to be made at District level. The housing developer may or may not have the contractual arrangements in place with a surface or mineral owner to allow this to happen, and the extended timescales introduced by a prior extraction phase may not suit the obligations of either the developer or the local housing plan.

Another option may be to work, process and use the mineral on site in the building of houses and infrastructure. Depending on the practicality of this a variant might be to take mineral offsite to a local mineral operator for processing and bring product back to site.

The author has assessed a site where some gravel was present at very shallow depths below surface and its' best use was to leave it in-situ where it performed the function that imported oversite material would usually do.

Site investigation data assessment

A challenge for the practitioner carrying out a mineral assessment is the volume and quality of site investigation data available with which to form a robust professional opinion. Various sources of on-line and paper data are available to be interpreted by a geologist and in conjunction with pre-development ground investigation results it may be possible to form a robust view without invoking specific site investigations. Such investigations may be necessary however.

So what is a housebuilder or solar farm developer to do? The first thing is to be aware of the more rigorous application of sterilisation policies and make the most cost effective use of routine ground investigations undertaken for foundation design, archaeology or drainage design. Two simple steps that will assist a minerals professional are as follows:

Ensure that trial pits are taken to sufficient depth. If, for instance, gravel is encountered its' thickness should be fully proved down to underlying bedrock. If these exceed the typical depth of an excavated trial pit say 3.5 to 4.5 metres then drilled boreholes may be needed.

Retain multiple bulk samples of especially granular material but also clean clays.

The second thing if such material is encountered is to seek advice from an industrial materials geologist before submitting samples for laboratory testing. When Particle Size Distributions are being carried out for drainage potential, for instance, the marginal cost of adding some sieve sizes that meet the aggregates specifications is very low. Other appropriate tests can be conducted at fairly modest cost.

The third thing is to seek appropriate advice early. If mineral, especially something readily identifiable like sand and gravel, is indicated on a proposed site then retain a suitable geologist early in the project. If drilled boreholes do become necessary or revisions are required to a standard ground investigation then it is usually more cost effective to do these when other plant is mobilised and the potential developer has access to the site. A suitably experienced geologist will be able to design an investigation that makes good use of existing data and is cost effective.

A number of medium size multi-disciplinary consultancies have experience in industrial mineral assessments and some small consultancies exist where the Principals have previous direct management responsibility for mineral assessment and quarry project development within the major quarry companies. Wardrop Minerals Management is one such company and can direct clients to other consultancies as appropriate.

In summary, being aware of the focus on mineral sterilisation policies should enable developers to take early advice and minimise the additional investigation, testing and reporting requirements that can arise where minerals of economic importance may be present.

Note

Permanent surface development in this context typically includes built development; house building; factory building; car parks; or solar farms and the promotion of these sites in local plans.

Sterilisation policies can also be known as safeguarding policy or mineral safeguarding or MSA.

Duncan Wardrop
Wardrop Minerals Management
October 2019

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Minister, Ladies and Gentlemen:

It is a privilege to be able to respond on behalf of the Mineral Industry Research Organisation to DEFRA's Review of the Sustainability Fund Research Projects. MIRO and English Heritage have selected a most interesting venue for this launch and The Wellington Arch is perhaps slightly more relevant than many people might at first think.

Further information

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