Posted August 4, 2020
Fears that some sand deposits are being overused, combined with increasing evidence that the dredging of rivers and seafloors causes vast damage to ecosystems and coastal communities, bring the sustainability of this vital material into question.
At the end of May 2020, when workers at the new nuclear reactor at Hinkley Point C began to pour concrete, they didn’t stop for three days. A time-lapse video shows 12-foot mechanical arms hovering over the disk that would form the reactor base, setting it in sections like an enormous 3D printer. While exact formulas for concrete are often trade secrets, the main ingredient is aggregates: gravel and sand. Looking out at the beige megaproject from Burnham-on-Sea – which, with the second longest tidal range in the world, appears as an endless beach at low water – you’d never think we need be worried about using too much sand.
The Hinkley pour (the second of two) is the largest continuous concrete pour ever to take place in the UK. Its 9,000 cubic metres of concrete base broke the Shard’s record of 5,500 cubic metres set in 2013. These records are dwarfed, however, by the global competition. The last three years saw Russia’s lofty Lakhta Center’s record of 19,624 cubic metres swiped by the Jebel Ali residential development in Dubai with 21,580 cubic metres, which in turn was shot out the park by India’s Polavaram Dam, a structure that spanned the Godavari river with 32,500 cubic metres of concrete. Meanwhile, huge development growth in China meant that the country got through more cement between 2011 and 2013 than the US did in the entire 20th century.
The use of sand for such mega projects, combined with its use in more basic construction, road building, beach nourishment as well as glass and computer chips means it is the most traded commodity by volume, after water. Mining takes place across the world and is dug from pits on land, dredged from riverbeds, and scooped up from the seabed. The UN estimates that we use 40-50 billion tonnes of the material a year, enough to cover the continent of Africa in a layer of sand a milimetre thick. It is already responsible for 85 per cent of all mineral extraction, and rates of extraction are increasing. Pascal Peduzzi, the UN’s voice on sand, warns that ‘we are approaching a future where access to this resource is a critical barrier to sustainability, and the full costs of uncontrolled extraction come due’.