Published in March 2005 Australian Longwall Magazine

Longwall mining might be the best thing that ever happened to nine vineyards in the Hunter Valley. Sound like a contradiction in terms? Surely longwall mining under a vineyard has the potential to place coal companies and viticulturists at loggerheads. This isn’t the case at Xstrata Coal’s Beltana longwall mine. A unique program developed in consultation with the wine community allows vineyards and longwalls to co-exist peacefully.

The Beltana punch longwall mine is located in the heart of wine country near Singleton in New South Wales’ Hunter Valley. The lucrative local wine industry attracts more than 1.5 million visitors annually, generating at least $300 million, and employing almost 6000 people.

Beltana is no small business either. The longwall started production in June 2003 and rapid ramp-up meant 5.79 million run-of-mine tonnes were produced in its first full year of operation. At 2005 contract export prices and with 27 years left in its project life, Beltana means big bucks.

Beltana’s longwall blocks are situated east-west, with depth ranging 50-200m. Coal is extracted at a height of 3m on the Whybrow seam, with a face width of 260m.

About 30 longwall blocks in four seams are expected to undermine existing vineyards. The mine layout has been designed to minimise impact on the vineyards and the surrounding environment. This includes the orientation of the longwall blocks parallel to the slope on the ground to reduce surface drainage issues and the staggering of the blocks in underlying seams to reduce the cumulative degree of subsidence, predicted to range from 0-2000mm per seam.

With comprehensive monitoring and reporting requirements for surface and groundwater issues in place, Beltana received development consent on February 23 2004, the mining lease was granted on April 5 2004.

Full subsidence management plan approval is now required for the start-up of longwall four in March this year. The application was lodged in September 2004 and covers site information, subsidence prediction, community consultation, subsidence impact and statutory requirements.

While the plan covers public road and telecommunications maintenance, as well as aboriginal heritage, the major part looks at private property subsidence. Management plans have been developed for all properties to be undermined, and include prior-, during- and post-mining management strategies.

Each property management plan includes an assessment of the impact on surface storage and drainage; an irrigation system assessment; inspection and testing program; implementation of a vineyard monitoring project; and a compensation and acquisition process.

Overseeing the environmental responsibilities at Beltana is environmental coordinator David O’Brien, with responsibility for environmental approvals, environmental management, and consultation with both the community and government. He will also coordinate a unique vineyard monitoring program.

The program was established in consultation with the local community, NSW Agriculture, the University of New England (UNE), and consultants, including world-renowned vineyard expert Dr Richard Smart.

“The program draws heavily on precision viticulture techniques, encapsulating the monitoring and management of spatial variability in vineyard productivity. The heart of precision viticulture is the use of global positioning system (GPS) technology to geo-locate measurements of vine productivity, or any other parameter, for that matter, that influences the productivity of a vineyard,” said monitoring program leader UNE associate professor David Lamb.

“Many different precision viticulture technologies are being brought to bear in generating the enormous amounts of data that will allow us to quantify any changes in the productivity of the undermined vineyards, if they do occur,” he said.

The technologies include regular multi-spectral satellite imaging, electromagnetic soil surveys, on-the-go yield monitoring using GPS-equipped mechanical grape harvesters, telemetry-linked capacitance soil moisture probes, and point sampling of grape quality.

“Given the concept of precision viticulture has only been around since 1999, the vineyard monitoring program conducted by Beltana represents the most comprehensive vineyard data collection exercise in the world,” Lamb said.

“Local vineyard owners are actively involved in the design and ongoing refinement of the monitoring program so that not only do they recognise the benefits of the technology used, but actually utilise the generated data as part of their ongoing vineyard management. The application of these technologies will also be shared with the rest of the Hunter Valley wine community,” O’Brien said.

Quickbird satellite imagery, capable of discerning objects on the ground as small as 70cm, is used to look for any changes in the vigour of vine canopies and between-row cover crops.

A GPS-equipped electromagnetic induction soil survey unit will also be deployed twice a year to map relative changes in soil texture down to a depth of 1.8m, the depth of most of the vines’ root systems.

An electronic yield monitor has also been fitted to a new Braud mechanical harvester to acquire detailed yield maps of each vineyard.

Three capacitance soil moisture probes have been installed along a single row of grapes, corresponding to the expected locations of maximum and minimum subsidence. The soil moisture data (logged every ten minutes) will be used to look for any changes in the demand for irrigation along a single management unit.

The final layer of information is the detailed sampling of fruit quality descriptors such as sugar (brix) and acidity. This data is acquired from over a thousand vines located throughout the undermined yards. All of the information generated in this project will be combined in a geographical information system and then plugged into an interactive computer-based system to allow researchers to interrogate various data layers and look for interactions.

“Given that the data acquisition spans a moving footprint which predates undermining by at least one year, and post-dates subsidence by at least two years, if there are any changes that occur in these vineyards then we should be able to see them,” Lamb said.

O’Brien said the project had a number of spin-off benefits other than ensuring the mine met statutory requirements.

“The project has proved a valuable tool for vineyard owners to improve their business, as well as introducing technologies to the Hunter Valley to benefit the wider community.”

Representatives from UNE regularly visit the individual vineyard owners to provide them with the generated data, and to assist growers in interpreting the numbers.

Grape growers can use the data to assess the uniformity and quality of their yields, possibly prompting changes in irrigation patterns or pruning methods to increase uniformity across the vineyard. The information can also be used to selectively harvest the vineyard to identify high quality grapes for premium wines, potentially increasing the maker’s profits.

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