Will sand be our new battleground?
It’s the stuff of which cities are made, but New Zealand might lack the appetite to carry on mining it. Katy Jones reports.
It is the natural resource we use most of worldwide, after air and water, and word is it’s starting to run out. Sand is being described as one of the most important commodities of the 21st century.
It’s what modern cities are made of; the main ingredient in concrete buildings and asphalt roads, computer screens and microchips.
Extracting sand is estimated to be a $70 billion global industry, according to the United Nations, and more than
40 billion tonnes of sand and gravel are estimated to be extracted every year.
While the world may seem to have an abundant supply of this sought-after commodity, soaring demand has seen beaches and riverbeds in some parts of the world stripped, to devastating effect.
In Indonesia, more than 20 islands are believed to have disappeared in just the past 20 years, due to sand mining.
Countless fish and birds are being killed by river sand mining in India, while miners have torn up hundreds of acres of forest in Vietnam to get at the sand underneath, according to investigative journalist Vince Beiser.
The Los Angeles-based writer is about to publish a book about the global market for sand; a market he says has been fuelled by an explosion in urban growth, especially across the developing world, over the past
20 to 30 years.
‘‘Today there are 4b people living in cities . . . cities are growing at a rate and on a scale that has never happened before.
‘‘When you have development going on at such an incredibly rapid pace, and weak laws protecting the environment, then you have people just stripping riverbeds and beaches bare to sell those sand grains to developers, to people who are building Shanghai and Mumbai and so on.’’
Desert sand is not suitable for use in construction materials such as concrete (its windshaped grains are too fine), so sand shaped by water has become the grain of choice in many countries where development is booming.
In China, sand mining in the Yangtze River caused its banks to collapse, taking out people’s homes and farmers’ fields, Beiser says.
Legal extraction moved to Poyang Lake, the biggest freshwater lake in China, and now the biggest sand mine in the world.
‘‘There are a lot of places where all the sand you can get at easily is gone,’’ he says. ‘‘Companies are having to go ever further, go to greater and greater lengths and cause more and more damage to extract the stuff.’’
How widespread is sand mining in New Zealand? Sand is extracted from New Zealand’s beaches, ports, quarries and rivers, but just how much and where is not easy to sum up.
There are are no central statistics on the extent of sand mining.
The closest thing is a voluntary survey of quarries by New Zealand Petroleum and Minerals, which puts the combined amount of sand, rock and gravel produced by quarries at about 30 million tonnes a year.
Regional councils, asked how many sand-mining activities were consented in their areas, reported between zero and 26, ranging from harbour dredging, to dune extractions for commercial purposes and flood defences.
Perhaps the best indication is the concrete industry, where most of the sand extracted in New Zealand is understood to end up. Roughly 3.5m tonnes of sand a year is used to make concrete, which is being produced in near-record amounts.
Sand extracted from the sea, including some from harbours, accounts for about 15 per cent, according to the industry body, Concrete NZ.
Some of the rest is dug up from rivers, but most is manufactured sand, known as fine aggregate, which is made from crushed rock.
Compared with the amount of sand used in concrete, little of New Zealand’s sand is shipped offshore.
However, last year saw a big jump, with 4000 tonnes of silica and quartz sands worth $1,769,980 exported, compared with 97 tonnes the year before.
Statistics New Zealand said the increase was mainly due to exports to New Caledonia. But where it was extracted from, and by whom, was confidential.
Big players
Two long-standing sand-mining operations north of Auckland are allowed to dredge more than 380,000 cubic metres (m3) a year combined.
There’s consent for 308,000m3 a year at Kaipara Harbour,
where sand has been pumped aboard barges for nearly 30 years.
And 76,000m3 can be taken a year in water 5 to 10 metres deep in the Mangawhai-Pakiri embayment in the northern Hauraki Gulf.
Coastal permits allowing the company McCallum Brothers to dredge at Pakiri were extended in 2009, when the High Court
upheld an Environment Court decision that natural sand replenishment would compensate for sand taken.
The science is still being argued.
Pakiri is a finite sand system, according to Jim Dahm, who has worked as a coastal scientist for more than 40 years.
‘‘It’s got all the sand that it’s pretty much ever going to get,
and anything you draw is going to be replaced ultimately, in the long term, by erosion of the dunes.’’
The beach sands moved onshore at the mining site after sea level rose to its current elevation about 7500 years ago, after the last glaciation, but that net onshore supply has now largely ceased, the Thamesbased consultant says.
If shell content from dying organisms was coming into the beach system at a rate of nearly 100,000m3 a year, as argued by some, the beach system would be far bigger than it is, Dahm says.
While sand is being replenished in the ‘‘humungously large sand system’’ at Kaipara Harbour on the west coast of the upper North Island, drawing sand from east coast beaches is ‘‘nuts’’ in the face of sea-level rise.
‘‘For east coast beaches, the figures generally vary between the potential for 20m to 50m erosion with 1m sea-level rise, and we’re expecting 1m or 2m as a minimum.
‘‘So the last thing you want to be doing is sucking sand out of it.’’
McCallum Brothers declined to comment, referring to the Environment Court decision and resource consent requirements.
A lot of the damaging sand mining in New Zealand, however, is a thing of the past, Dahm says.
‘‘Generally in New Zealand, we became aware of the issues of sand mining in the 1960s and 70s.
‘‘There was a lot of sand mining done in New Zealand in the early 1900s, around Manukau Harbour, Thames coast, Coromandel beaches, Auckland beaches, a lot of irreplaceable sand was removed.
‘‘So most of our really bad sand mining is historical.’’
Iron sand, meanwhile, has been mined onshore for more than 40 years.
The black sand contains the mineral iron ore, which is extracted to make steel.
The Taharoa Ironsands mine in Waikato has been reported to export more than $150m worth of sand a year, mostly for use in factories in Asia.
When the mine opened in
1973, it gained access to an estimated 300m tonnes of iron sand concentrate. In 2013, it was forecast to have another 15 years to run.
The Waikato North Head mine produces up to 1.2m tonnes of iron sand a year, for use in the New Zealand Steel mill at Glenbrook. The deposit is estimated to contain more than
150m tonnes.
Information about Vince Beiser’s book, ‘The World in a Grain: The Story of Sand and How It Transformed Civilization’, can be found at https://www.penguin randomhouse.com/books/
537681/the-world-in-a-grain-byvince-beiser/