SRK Consulting (Australasia) and Novo Resources have teamed up to trial an innovative groundwater sampling method, believed to be a first in the Australian mining industry.

SRK has been conducting monthly and quarterly groundwater quality sampling at Novo’s four exploration sites in the Pilbara, Western Australia, since February 2018. The consultant has been gathering a picture of how the groundwater chemistry (and water level) naturally changes over time before mining activity begins.

“We believe there have been no similar tests in the mining industry in Australia, so Novo was excited about the prospect of being at the forefront of a new technology,” SRK Principal Consultant (Hydrogeology) and Practice Leader, Brian Luinstra said.

Traditionally, pumps are used to collect groundwater samples that are representative of the groundwater within the aquifer, by attempting to remove and replace stagnant water in the monitoring bores that have accumulated between sample runs. It is important to avoid sampling of stagnant water because it represents a change in chemistry, providing inconsistent results.

According to SRK Graduate Consultant (Hydrogeology), Michael van Mourik, who is running the field campaign for Novo, the traditional pumping method has many pitfalls. These include frequent pump breakdowns, significant amounts of labour and time required, energy-intensive tasks, difficulty acquiring replacement parts when working in remote locations, and environmental waste from a large number of plastic tubes needed. He was convinced there was a better way to get groundwater samples that would not only save his time but provide savings for the client too.

“I contacted our Vancouver and Denver offices to see what they were doing and if they were having the same issues (which they were),’ he said.

“They recommended some different pumps that were even more expensive but slightly more reliable. But there was still no guarantee that we wouldn’t run into similar problems.

“However, the SRK Denver office was using the HydraSleeve™ sampler, and had been doing so for a couple of years.

“When I first heard about it, I was a bit sceptical as I thought pumps were the only way to do this. So, I started to do my own research into what they were doing and the theory behind it and ultimately convinced myself that they were onto something. That’s when we started looking into it more seriously and discussing whether it could be a viable option for us to use at Novo’s sites.”

Effectively a ‘high-tech plastic bag’, the HydraSleeve™ is a no-purge groundwater sampler, which captures a ‘core’ of water from any discrete interval in the screened portion of a well without disturbing the water column. The bag remains sealed except during sample collection, then reseals itself as it is pulled up, ensuring only the required section is sampled and not the stagnant water. It is very quick, cheap and requires less effort.

van Mourik brought his ideas to Luinstra, who fully supported his younger colleague’s findings. The team then approached Novo to see if they would be interested in testing this sampling method at one of its projects.

Novo’s Chris Goti, General Manager – Environment and Heritage, said he was not aware of the HydraSleeve™ technology before SRK approached Nova with the idea last year. He said it instantly looked like a great way to lower costs and speed-up sampling, particularly important in challenging environments such as the Pilbara.

“We didn’t have any hesitation in wanting to support the testing of this technology, but the trial had to be undertaken in a way that wouldn’t compromise the integrity of the sampling programs already in place,” Goti said.

“Once adequate controls were in place, Novo was keen to support SRK’s initiative as an industry partner.”

SRK conducted sampling campaigns in December 2019 and March 2020 on seven wells at Novo’s Beatons Creek gold project in the Pilbara. The initial results showed comparative results to traditional pumping. As the hydrogeology team predicted, there were also considerable time, money, and health and safety benefits. The HydraSleeve™ is also incredibly easy to transport and can be used effectively in all mining environments.

“Historically, people have said you can’t just sample the hole because you are not getting that recharge of flow to the bore,” Luinstra said.

“But we have preliminary evidence that suggests you can get similar results from using the HydraSleeve™ sampler as you do from pumping.

“And if it’s 45 degrees and you don’t have to stand next to the well for an hour, that makes a big difference.”

Sampling from the same seven bores in December and March has shown similar promising trends, and van Mourik is confident that further analysis of the data will prove the technology can be applied on current and future clients’ projects, potentially replacing pumping as the standard groundwater sampling method.

“Our colleagues in the United States aren’t really using the old method anymore, and colleagues in Canada are starting to use HydraSleeve™ units now too,” van Mourik said.

“I don’t think Australia is that far behind.”

Novo is also keen to adopt the new sampling method on its other projects, where possible.

“The methodology is now used in all 50 states in the United States, and is expected to eventually be adopted across Australia, so it makes sense to make the switch now,” Goti said.

“It’s a great initiative from the SRK hydrogeology team.”

Having access to SRK’s global nous was invaluable in bringing this technology adoption to fruition in Australia, van Mourik and Luinstra agreed.

Luinstra said the international exposure was not only valuable to SRK staff, but also a huge benefit to its clients. ‘If we were just a Perth-based company, we wouldn’t have those experiences in Denver to draw on,’ he said.

‘We do bring experience from around the world and this is an example of doing that. The other thing is having a client who agreed to testing and fully supported us. Novo paid for extra laboratory analysis and for extra people on-site to help us get it set up. So, to have that was pretty special and full credit to them.’