Hauraki Rail Trail

PART 2:   Paeroa to Waikino  - 28 May 2021

The air was still frosty as Keith, Tony and I gathered at 9 a.m. for the start of our cycle ride through the Karangahake Gorge.  From our starting point at Paeroa, 10 meters above sea level, we would be following the Ohinemuri River upstream to Waikino, a gentle climb of 69 meters over the 13 kilometer distance.  The nice thing about the Rail Trail is that, apart from a few special exceptions, the maximum gradient on the New Zealand rail network was set at 1 meter rise in 35 meters distance.  On this section of the trail the gradient averages out at a very easy 1 meter rise in 188 meters of pedalling - hardly noticeable.

From Rotokohu Road in Paeroa, the trail follows alongside the road, turning left along Te Moananui Flats Road and then through farmland along the West bank of the Ohinemuri River to the tiny settlement at Karangahake.  The Paeroa to Waihī railway was built to enable access to transporting gold from Karangahake Gorge.  The Coromandel was the first place gold was discovered in New Zealand, initiating feverish migration to the area, with prospectors seeking to find their fortune.

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Paeroa to Waikino - part of the section shown in blue.  Shorter than the previous ride from Pipiroa to Kaiaua (green dotted line), but every bit as enjoyable.

The first gold in the Coromandel was discovered up the peninsular at Driving Creek.  This discovery caused the first surge of prospectors, mostly diggers and panners, working the many streams collecting small nuggets of alluvial gold.  However, accessible alluvial gold ran out after only a month!  It wasn’t until a decade later the area was declared a goldfield following the discovery of gold-bearing quartz, hidden in deep veins within the rock.  Unlike alluvial gold, quartz reefs required machinery and equipment to mine the ore, crush it and extract the gold, a process far beyond the capabilities of small-time prospectors.  So eventually companies took over from individuals, setting up stamper batteries and beginning large scale mining production.  The first commercial use of a new process using cyanide solution to recover gold was at the Crown Battery at Karangahake in 1889.

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At Karangahake the trail crosses the river on the original railway bridge and straight into a 1,089 meter long tunnel through the hill.  Since walking through the muddy tunnel some years ago, it was nice to find that the floor of the tunnel has now been paved, with drains along each side.  Originally built with a length of 1,022 meters, it was later extended at the Waikino end to allow for realignment of the Highway over it, thus eliminating a dangerous rail crossing.

The tunnel construction started in September 1900 and was completed, lined with bricks and the rail laid, in March 1905.  This great feat of engineering, passes through a spur of very hard rock, requiring a tunnel 1,022 meters long with a 1 in 50 gradient.  It is the steepest part of the trail and the early coal trains really struggled to get a grip on the tracks.  Some required several attempts to get through.

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A 1 in 35 gradient (shown in red) is the maximum set by the New Zealand rail system without requiring a Fell system.  The steepest section of the North Island Main Trunk is 1 in 52 on the Raurimu Spiral.  The Karangahake tunnel is slightly steeper at 1 in 50.

Cutting the Karangahake tunnel was hard and dangerous work, hampered by water seepage and flooding.  Up to 70 men at a time were employed on the excavation of the tunnel and construction of the railway line, and, as is often the case, men died in accidents during the project.  In April 1904 the first fatality occurred.  David Dean died from injuries incurred by a fall of earth when he and another man were shoring up a portion of the tunnel where a slip had occurred earlier.  Then on October 18, 1904, Fred Shaw and Walter Ings were just going on day-shift when the side of the tunnel collapsed on top of them, burying them under rock and earth.  Walter Ings had his back and both legs broken and died two hours later.  Shaw had one leg broken in three places and sustained severe flesh wounds.  He was taken to Thames Hospital but died from heart failure nearly three weeks later.

On Friday September 23, 1904, men working from each end thought there were still a few metres to go when the tunnel was holed through at 8 p.m.

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Primitive lighting was installed years ago, providing a dim pool of light every 100 meters or so.  A torch or bike lamp is a must.

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The trail enters the site of the Victoria Stamper Battery ruins,

now home to a miniature railway tourist attraction.

The tunnel emerges straight onto another bridge back across the river.  At this point there is the option to lock the bikes up and walk the 2 Kilometer "Windows Walk" - a spectacular hike through a side gorge and another smaller tunnel.  Time didn't permit us to undertake that detour on this occasion, but it's highly recommended if you get the chance!  Instead, we carried on along by the river, at first not recognising another cyclist coming towards us. Then, something prompted me to turn around for another look.  Sure enough it was George, who had started his ride at the Waikino end to meet the rest of us on the trail.  A short time later we came to the ruins of the Victoria Battery, the largest of the quartz processing plants beside the Ohinemuri River in the Waikino area.

The Victoria Battery was built in 1897 by the Waihi Gold Mining Company to process ore from its Martha Mine in Waihi.  The facility initially had 100 stampers to crush the ore, powered using Pelton wheels - an impulse-type water turbine invented by American inventor Lester Allan Pelton in the 1870s.  In 1902 a further 100 stampers were added with a steam engine to drive them.  This became the largest stamper installation in New Zealand and had an 8 kilometre railway between it and Waihi.  The ruins of the battery are managed by the Department of Conservation.

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The Victoria Stamper Battery as it was in 1916, looking north from Waikino towards the Karangahake Gorge in the top right.

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The remains of an old Pelton wheel, once used to power the stampers, lies decaying among other machinery.

The cyanide process of extracting gold from crushed ore was successfully tested at one of the nearby Karangahake Gorge mines and this process was also used at the Victoria Battery.  The battery’s cyanide tanks were constructed in the early 20th century.  The Victoria Battery continued operating until 1952, closing at the same time as the Martha underground mine.

The profits from the gold did not come cheaply in terms of environmental costs.  The advent of the cyanide process for gold extraction, first trialled internationally on a large-scale commercial basis by New Zealand Crown Mines at Karangahake in 1899, provided an efficient method of gold extraction, enabling approximately 90% of the gold content to be recovered.  The waste-rock by-product of ore crushing and amalgamation or cyanide processing resulted in approximately 250,000 Mg per year of mercury, arsenic, and cyanide contaminated mine tailings being discharged directly into the Ohinemuri River and its tributaries from 1875 to 1955.  A devastating flood on 14 January 1907 deposited large amounts of mine waste across the floodplain of the Ohinemuri and Waihou rivers in the vicinity of the township of Paeroa.  Contamination is still evident today in the lower reaches of the Firth of Thames.

By 10:30 a.m. we reached the old railway station at Waikino, now a cafe.  Time for a cappucino, a bluberry muffin, and 30 minutes of relaxation by the open fire before our return trip.

 

The weather had warmed up considerably by now, so much that Keith decided that it was more comfortable to cycle much of the way back without clothing.  The return ride was noticeably easier, being a gentle downhill slope and with the breeze behind us.

 

At around 12:20 p.m. we arrived back in Paeroa - a short but fascinating section of the Hauraki Rail Trail completed.

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