The red red stones of home

It’s probably the last accessible deposit of red scoria left in the country and, at five million cubic metres, there’s plenty of it. This resource would have also have to take the prize for being the most colourful stone in the country. BY ALAN TITCHALL.

Taupo Scoria commands a view of the big lake from its western heights that you could sell to tourists. From the top of the quarry’s windy northern ridge, Graham Seay sweeps his arm in a wide arch that takes in a sweeping panorama of the lake, Taupo township and Mt Tauhara in the background.

Below us in the pit, a concentrated palate of different shades of red and maroon changes in front of us as the sun fights through rain clouds. In the longer view, the mood of the red scoria also changes with the season and between wet and dry, and some winters even gets a sprinkling of snow.

“We come up here some mornings and it’s just stunning,” Graham (pictured below) says quietly.

When he says ‘we’ he means the family – brother Bruce who runs Seay Earthmovers, the heavy machinery division of the company and sister Judy who works in the administration office.

The Seay family were originally from Auckland and arrived in Taupo some decades ago to work on a heavy machinery contract, fell in love with the region and never went home.

The 45-year-old scoria quarry, however, is a recent acquisition, bought five years ago after being approached by quarry veteran George Cunningham who knew of the family from their Auckland days in the heavy machinery business.

“We were looking for a change and our father Hartley Seay had worked in scoria quarries in Auckland so we knew something about the business. We decided to give it a go and it has just revitalised our interest in everything,” says Graham.

The quarry operation was fairly run down when they bought it and basically a two-man operation. One of biggest problems, he says, was a lack of open areas and storage space.

“We caught up on stripping that hadn’t been done for some 20 years and moved overburden into areas that were already worked out.”

In addition to under-grounding the power, this left room for stockpiling and a new, if very basic, equipment setup from Keith Neiderer in Auckland to screen the fines. The company has taken steady approach to adding more plant as required.

“We built it up slowly as we didn’t want to end up with equipment we had no need for. There’s only a limited market for commercial volumes of scoria fines while we search for new markets, and we are getting there.”

The resource is an entire hill of red scoria laid down during old volcanic eruptions in the lake region that formed small scoria cones, typically about 500 metres across and up to 200 metres high. There are a number of examples of these between Taupo township and Acacia Bay on the north-western side of Lake Taupo.

Taupo Scoria, on a 35 year Landcorp lease, bites deep into the eastern side of a steep hill of scoria that is typically around 200 metres deep (with little over-burden). The western face is farmland, and with no plans to open this side, has already been extensively planted with natives trees.

The aggregate is soft enough to excavate straight out of the face with a loader but an excavator is also used. Only about five percent of the scoria is crushed, the rest is simply screened and stockpiled.

As a child, Graham fondly remembers visiting his father who worked scoria quarries in the Auckland region as a machine operator in the 1970s.

“Auckland’s scoria has a lot of different colours, including greens and yellows, and a lot more rock than our resource which averages a grade of 100mm and varies between bright red and brown.”

The resource is made up of big bands of different red shades that are targeted depending on what market is ordering at the time, he says. The browner scoria is graded for the construction industry for the likes of drainage, while the vibrant coloured scoria is reserved for export and the local horticultural and landscaping markets.

The quarry already exports 20 containers a year to Australia, Japan, and New Caledonia for the drainage, decorative and hydroponics markets. Aggregate is screened from between 1mm and 6mm grade, which gets rid of more fines. The hydroponics market uses between 2-4mm, depending on what the crops.

One of the biggest construction sales for the quarry was for the Taupo Motor Racing circuit after it experimented with cars spinning into various aggregate material as a safety buffer on track bends and corners. They found scoria not only stopped the car, but still allowed it to drive back out on the racetrack while other material left it bogged down and stranded.

Last year, Taupo Scoria found a large deposit of basalt up to 13 metres deep in places and other seams six metres thick, making it the only basalt deposit in the central North Island.

“The basalt is blasted and broken with a rock hammer and crushed by contractors. The Quarry has recently been supplying Fulton Hogan with basalt aggregate for the Taupo Eastern Arterial Project where some of our earthmoving equipment has also been working.”

Meantime, the scoria stockpile is not getting any smaller.

“It’s like a big red tide coming to swallow us up,” Graham jokes.

“I’m hopeful I can turn it back with the hydroponics market. We have done exhaustive testing on different grades.”

The growers who have used scoria for hydroponics swear by it, he says, but it is a conservative market he concedes. Numerous articles testify to scoria’s properties as a natural material for hydroponics with its high degree of root aeration and free draining nature. Plus, as a natural material, it can be reused after cropping for ornamental plantings.

Then there’s the potential to increase exports to markets such as Japan with its ‘gardening culture’ and affinity with strong red colours.

“Japan does have it own scoria resources but, like Auckland, it is tied up in untouchable public lands. The country also has a big focus on becoming self-sufficient in growing food but there’s a scarcity of land. They get three times the food production out of a hydroponics set up.”

Strength to weight and thermal properties also make scoria an ideal new construction material, Graham says.

“We are looking at building trade exterior plaster finishes and light weight concretes. Scoria has incredible thermal properties that we are sure people will eventually find a purpose for.”

While the family wait for their scoria fines to reach new markets, they say the quarry has brought them a new lease of life and has help them ride through the construction downturn.

“The quarry has made us much stronger and added an exciting future for our company as we continue to investigate new markets for this unique resource.”

After 30 years in earth moving, the Graham adds that the family “just love this industry”. “Earthmoving is very competitive as contractors can move their gear around the country to one job to another.

“A quarry is a fixed asset and you can only truck the resource so far. For this reason it is far friendly and more trusting commercial environment to work in.”