Wednesday, September 08, 2021

Nuclear Theddlethorpe 03

Geology is what counts.

Useful summaries of the Theddlethorpe area’s geology are to be found in RWM’s own reports, commissioned from the British Geological Survey, ‘Eastern England Regional Geology’ (EERG)

and ‘Eastern England Subregion 2’ (EES2).

It’s worth noting that we do know quite a lot about the geology of the region. This from page 3 of EERG:

There are more than 690 boreholes drilled to more than 1,000m depth in search of coal, oil and gas, water and mineral salts (evaporites). This information is also supplemented by extensive geophysical investigations including studies of the Earth’s gravity and magnetic fields and seismic surveys. The distribution of rocks in this region is therefore reasonably well known at the national scale. There are a number of shallower boreholes that provide information on groundwater above 200m, but very little information within and deeper than the depth range of interest for a GDF, 200 to 1,000m below NGS datum.”

The sequence of rocks is summarised in Figure 2, page 8 of EERG. The sedimentary rocks comprise various layers of pervious rocks such as sandstones and impervious clays and mudstones. Nuclear waste would need to be stored within a sufficiently thick layer of impervious rock and even if too thin to hold a depository, thinner impervious layers higher in the sequence might help seal lower layers from groundwater movement.
There are various possibilities but the mudstones of the Triassic, such as the Mercia Mudstone Group, are probably the most obvious target for a GDF.

It is one thing finding a rock layer that is sufficiently impervious to movement of water (and hence radionucleotides) and might therefore provide a safe location for a GDF, but the issue in our area is what else is present. If there is a likelihood that material useful to a future civilisation is present, such as oil, gas or coal, the location will be unsuitable, as a future search for these resources could inadvertently breach the integrity of a nuclear waste depository.

There are hydrocarbons in rocks at a number of horizons right down to the underlying Carboniferous rocks where we find the Coal Measures. Gas has been found in commercially exploitable quantities at Saltfleetby, 7km from the old Theddlethorpe Gas Terminal, and oil at Keddington. Coal underlies the whole area and although too deep to be mined by conventional means, underground coal gasification has been seriously considered. There is currently no commercial interest in exploiting this resource and the climate crisis demands an end to burning fossil carbon but we cannot know what the people in future centuries may do and what technologies they may have. It is not enough to say that while there is gas at Saltfleetby, the gas field does not extend to Theddlethorpe. A future civilisation may have technologies that make our enhanced recovery methods appear primitive. They may exploit resources that we would consider worthless.

The existence of fossil carbon in the rocks below Theddlethorpe must mean that this is rejected as a location for a GDF.

But don’t just take my word for it. These two passages are from EES2:

Page 1. "There are known gas resources at Saltfleetby north of Mablethorpe. In this area the drilling is likely to have affected the way in which water moves through the rock. Also possible exploration in the future in this area means that it is more likely that future generations may disturb a facility. Parts of this subregion have Petroleum Exploration & Development Licences to allow companies to explore for oil and gas. This exploration is currently at an early stage and it is not known whether oil or gas in these licence areas will be exploited. RWM will continue to monitor how this exploration programme progresses. Parts of this area, immediately off the coast and in the Humber estuary, are Coal Authority Licence Areas allowing companies to explore for coal. It is not known whether coal in these licence areas will be exploited. RWM will also continue to monitor how this exploration programme progresses."

Page 4. "Resources There is a small gas field at Saltfleetby, just north of Mablethorpe (Figure 4a). It is less likely that this area would be suitable to host a GDF because borehole drilling associated with oil and gas exploration affects the way in which water moves through the rocks. It also presents a higher likelihood of inadvertent human intrusion in the future. These known resources would be taken into account in the siting of a GDF. Petroleum Exploration and Development Licences3 are currently held for much of the onshore part of this subregion and a small part of the inshore are (Figure 4a). There are also Coal Authority Licence Areas, in 2 inshore parts of this subregion off Hornsea and Mablethorpe (Figure 4b) and the Humber estuary between Kingston upon Hull and Grimsby. It is not known whether coal, oil or gas in these licence areas will be exploited, but they would need to be considered in the siting of a GDF."

It is clear that RWM have a policy of rejecting a site where there is a likelihood of fossil carbon resources. It is also clear that RWM know that there are fossil carbon resources beneath Theddlethorpe. Which begs the question why are they even bothering here?

Part One of this topic.


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