Offshore Teesside ~ A Potential GDF Location

In a recent article we highlighted the move towards offshore geological disposal. The next search process for a UK GDF has extended the available offshore strip from 5 to 20km.  We noted there that it is quite possible that an onshore GDF has simply become undeliverable anywhere in the UK. That article also suggested that given what we know about the unsuitability of Cumbria’s onshore geology, any future search process in Cumbria should be confined to the newly-extended 20km offshore strip of Copeland, within tunnelling distance from Sellafield.

In this article we will examine an alternative offshore site in eastern England, under the North Sea off Teesside.  The remarkable aspect of this option is that rather than costing £10-20bn to develop, it could potentially be developed at zero cost to UK taxpayers. The key to this is the value of the extracted spoil which significantly exceeds the extraction cost.  Any viable commercial mine should have this relationship between mineral value and extraction cost.  However we can instantly dismiss the majority of UK commercial mines – the presence of coal is an exclusion criterion for a GDF, since the risk of intrusion into the facility by a future generation is considered too great. In this case there are two mineral resources – a polyhalite seam at around 1500m depth, and a halite (salt) seam at around 1350m.

The mineral extraction rights for this area are currently owned by Sirius Minerals.  They plan to extract the polyhalite containing potassium, magnesium, sulphur and calcium for use as a fertiliser.  The shallower salt seam could be used for road de-icing.   The void left after extracting these minerals may have potential as a GDF.  Evaporites including salt are generally considered to be a suitable host rock for a GDF in part due to the property of keeping water away from the repository.  It also exhibits ‘salt creep’, where the salt deforms gradually over time due to its plastic nature.  While this is a negative attribute for the purposes of salt mining, it could be beneficial for a GDF in closing fractures created by the extraction process and forming a seal around the waste.

The US operate a GDF within a salt mine in New Mexico, although as we have reported in previous posts, some exceptionally poor working practices, involving the accidental use of organic cat litter to absorb moisture, led to a barrel of waste rupturing in 2014 and an extended closure of the facility. A recent analysis by the Los Angeles Times has estimated the cost of this mistake at $2bn  This happened less than a fortnight after a poorly-maintained 29 year old truck had caught fire within the same facility.  However, these are not reasons to avoid salt as a host rock, they are reasons to ensure that corners are not cut with staffing, training or equipment in whichever rock type a GDF is constructed.

There are a number of complications with this Teesside plan which would have to be overcome for it to succeed:

1.  The geology would have to be proven suitable.  In the late 1980s the British Geological Survey (BGS) studied mainland UK for Nirex and identified Teesside as a potentially suitable area for a repository. Professor Stuart Haszeldine of Edinburgh University supports this view.  Significantly, as Professor Haszeldine has made clear, the groundwater flow does not return to the surface, due to the impermeable salt layer which was formed by the evaporation of a sea.


Slide from a talk given by Professor Haszeldine in November 2012. The map shows the areas identified as potentially suitable for a repository by the BGS. The illustrations compare problematic groundwater flow found in onshore Cumbria with suitable groundwater flow in offshore Teesside.

2.  The onshore part of the licence area is within the North York Moors National Park.  National Parks have some of the highest level of planning and environmental protection in the UK.  The Park Authority is widely considered to have made the wrong decision when it approved the mine by the narrowest of margins in July 2015.  Sirius Minerals managed to get around the usual National Park planning rules forbidding major development, since the only place where the polyhalite seam exists onshore in the UK is within the National Park, and it was therefore able to claim that there were no alternative sites available in the UK.  That route around the planning rules could not be used for a GDF, since there are many alternative sites outside National Parks, as Nirex found.  Any GDF would have to be entirely offshore to keep it well outside the Park boundary, since National Parks (along with AONBs) are the most treasured parts of our countryside and this is entirely incompatible with siting a GDF.  Approximately two thirds of the mineral licence area is offshore so this should be achievable.


The yellow outline is the mineral licence area owned by Sirius Minerals. In addition to the recent onshore boreholes, 4 historic offshore boreholes shown here as red triangles also intersected this polyhalite seam, including one beyond the licence area.

3. The two seams are at approximate depths of 1350m and 1500m, which is below the 1000m level envisaged in the White Paper, but while this may necessitate greater spacing between higher activity (heat generating) wastes to avoid excessive heat building up, there appears to be no shortage of mine area, and of course with the value of the extracted mineral exceeding extraction costs (by a factor of around 5 for polyhalite in the company’s  projections), that shouldn’t add to the cost, even if as seems likely,  the company has been somewhat optimistic.

4. The community would have to agree for this to go ahead.  This is often a major hurdle and experience shows that communities which are distant from nuclear facilities are less likely to accept a GDF.   Sirius has approval for a large Mineral Handling and Harbour Facility on Teesside connected to the mine by a 23 mile tunnel.  This facility is well outside of the National Park and around 2 miles from Hartlepool Nuclear Power Station, which is due to begin decommissioning in 2024 with the anticipated loss of around 700 jobs.  It is possible that the wider power station site could be redeveloped into surface facilities for an offshore GDF, and a tunnel entrance could be located there on what is already a nuclear licenced site which currently houses some nuclear waste.  This is also close to the Teesside Steelworks, the majority of which closed in 2015 with substantial job losses. This is a heavily industrialised area in need of new jobs.

5. Sirius Minerals would have to agree to this joint venture.  At present they are in the process of raising funds for the first phase of this project.  Shareholders are paying a very high price in terms of equity dilution, bond interest, and royalty sales in order to secure this early stage funding, since this is rightly considered to be a high risk venture with risk of delay and cost overrun. The value of the company has halved over the last month since the announcement of these funding terms.  A government partner with access to 10 year funding at around 1.5% would transform the project.  If the company were to reject the idea, the government could choose to develop its own combined offshore mine/GDF facility adjacent to the licence area, so there are good reasons on both sides to work towards a joint venture.


As with any GDF project, getting this right would be a challenge.  The primary focus must be the geology.  The UK in particular appears to place far too much reliance on untested and untestable (over a relevant time frame) engineered barriers.  These barriers must only be used to complement good geology. We need to prevent fluid and gas migration to the surface for around a million years and only good geology has a proven track record of being able to do that.

While we have suggested that the newly-extended strip of offshore Copeland may have potential, RWM must broaden its horizons and recognise that after so many failed attempts, there are other locations beyond Cumbria which must be considered.  Other countries have succeeded in attracting more than one volunteer area, so it should be possible here.

Examining and comparing the suitability of a number of locations gives the best chance of finding and securing a suitable site, and reduces the danger that a government with no plan B will be tempted to press ahead despite poor geology.

If the use of this particular mine turns out not to be possible, due to political, geological or corporate difficulties, offshore Teesside still shows great potential and RWM must ensure that it makes an effort to engage with the Teesside community to investigate this area.  The idea of combining a GDF with a commercial mine must be seriously considered, as it has the potential to reduce or even cover the cost of building the GDF, while creating more jobs than a GDF alone.