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Engineered wetlands (foreground) near the former Baldwin’s Quarry site (background) protect the Whangamarino Heritage Wetlands (right) from industrial run-off.
Engineered wetlands (foreground) near the former Baldwin’s Quarry site (background) protect the Whangamarino Heritage Wetlands (right) from industrial run-off.

Commitment to protected wetland nets prestigious award

A Kiwi quarry operator who engineered a wetland filtration system to prevent run-off in his quarry polluting an adjacent world heritage conservation site has received the Institute of Quarrying’s most prestigious award.

Kerry Reilly, who operated the former Baldwin’s Quarry site – 75km south of Auckland – is this year’s recipient of the prestigious international Caernarfon Award. The annual prize is presented to the best paper at any worldwide Institute of Quarrying event that has contributed most to the technical, environmental or strategic advancement of the industry.

“I didn't set out to win any awards but this is a pretty special one and I'm very humbled,” Reilly said. “I didn't realise its significance until everyone started congratulating and explaining it to me.”

Reilly’s environmentally-focused project involved the design and construction of his own wetland that provides natural filtration of industrial run-off to protect the nearby Whangamarino Wetland, which was granted world heritage status in 1989.

The idea originated in 2005 – five years after Reilly began extracting greywacke from the site – when he realised the quarry’s internal eight-pond system could be breached during deluges, potentially sending silt-laden run-off down the hilly terrain, and directly into the protected wetland.

“I saw a big exposure for my business having deleterious materials entering the waterway, and I was really concerned about that,” he said. “I really felt it was going to be a nemesis forever if I couldn't create something to polish and enhance the water discharge from the quarry.”

Exacerbating the issue was the fact Reilly’s dairy farmer neighbour at the time, Peter Buckley, was also the chairman of the local environment council. He would be critical of any negative impact the quarry had on the surrounding ecosystem. 

Reilly approached Buckley and over three years devised a mutually beneficial scheme that would guarantee the removal of sediments from the quarry site, as well as nitrates and ammonia from the Buckley dairy farm, prior to the water entering the wetland.

Kerry Reilly, Caernarfon Award winner
Kerry Reilly, Caernarfon Award winner
“The whole idea is to have the water flowing but as slow as possible, which gives the microscopic particles time to drop out of the water stream before entering the Whangamarino Wetland”
Kerry Reilly, Caernarfon Award winner

He built a system that naturally diverts water from the quarry, across the farmland to an area consisting of five ponds covering 10ha. Each pond was constructed via an encapsulation method using quarry overburden. Farm run-off is also pumped and collected into the ponds where it converges with the quarry water.

Over time, the system has turned into a man-made wetland, which sees the industrial run-off flow in a circular motion through the chain of ponds. Each is connected with rocklined culverts, which further process the water. The entire watercourse is 520m, and has the capacity to withstand an impressive 75m3 of water per second.

The system also works as a stopbank for the quarry, and has stood up to major downpours in 2017 and 2018.

“The whole idea is to have the water flowing but as slow as possible, which gives the microscopic particles time to drop out of the water stream before entering the Whangamarino Wetland,” Reilly said.

The end product has produced a thriving ecosystem, which includes an abundance of native animal life and vegetation that possess the ability to clean water of pollutants.

“For example, Raupo is an amazing plant, and in its root structure there are rhizomes and bacteria that have the ability to clean and polish water, especially in nitrates and heavy metals – not that we have heavy metals leaving the quarry,” Reilly said.

A sustainable solution

Reilly was presented with the Caernarfon Award at the joint Institute of Quarry New Zealand/Aggregates and Quarries Association joint conference in Invercargill in July, where he was also the recipient of the Lyn Jordan Memorial Trophy for the best technical paper in the country.

“I had a vision and a dream, but I never appreciated how well it was going to work until I saw it,” he said. “Now it’s a legacy and it's going to get better and better.”

Reilly hoped the project would demonstrate many quarry operators were environmentally-minded, and took environmental management seriously.

“I wouldn’t call myself a greenie. I’d say I'm a practical person that could see an upfront investment could save you a huge amount of pain by the regulatory body. If you can leave something behind that works, and is maintenance-free, well you can't get any better,” he said.

“You can have consents to operate a business and it's all very nice, but if you don't look after your social licence, you can lose that business.”

He added: “These sort of engineered wetlands are used to manage and treat municipal waste water as well, so it's not just relevant to quarries. It's the natural solution to cleaning and polishing water in any situation really.

“Unfortunately, the world has depleted its wetlands, and many landowners have reclaimed them and filled them in, and chopped down all the vegetation around them. Now most people appreciate they have done themselves a big disservice because the wetlands are actually there for a reason. They do a magnificent job.

“All you have to do is watch, and learn from nature and then try and assist nature, because unfortunately nature works quite slowly.

“The problem lies in man trying to accelerate everything. We are always trying to go faster, and unfortunately when you speed up there is cost and a consequence. I’ve taken notice of that, and I’ve realised to get the result I wanted, I needed to slow the process right down – and it works.”

In 2015, the Baldwin’s Quarry was sold to Winstone Aggregates and is now known as the Winstone Meremere Quarry.

 

IMAGE Gallery

Quarry run-off (yellow arrows) travels along farmland into Pond 1, before circulating (blue arrow) through other ponds and into the protected wetland. Quarry run-off (yellow arrows) travels along farmland into Pond 1, before circulating (blue arrow) through other ponds and into the protected wetla
Quarry run-off (yellow arrows) travels along farmland into Pond 1, before circulating (blue arrow) through other ponds and into the protected wetland. Quarry run-off (yellow arrows) travels along farmland into Pond 1, before circulating (blue arrow) through other ponds and into the protected wetla
Industrial run-off moves through Ponds 2, 3 and 4 before entering the Whangamarino Wetland.
Industrial run-off moves through Ponds 2, 3 and 4 before entering the Whangamarino Wetland.
The former Baldwin’s Quarry was consented to produce 500,000 tonnes of greywacke per year.
The former Baldwin’s Quarry was consented to produce 500,000 tonnes of greywacke per year.

 

More reading:
Crushing stone with stone: Bryan Bartley, Jim Macdonald and the Barmac crusher
Ken Andrews: A passion for safety
Hong Kong’s visionary approach to quarrying
 

 











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