Tag Archives: Canada

Did you know not all penstocks are constructed using steel?

This post provides a background on an extraordinary feature of the walk between Wayatinah and Catagunya Power Stations along the Derwent River.   It is about one of the great surprises of this  ‘walking the Derwent’ project and, as such, reminds me that even the most ordinary of explorations can unearth new discoveries (for those not familiar with an industry – in this case, the industry involved with penstocks).

Okay okay okay I know some readers will have rolled their eyes wondering what a penstock is.  A penstock is a very large pipe that is laid downhill through which water falls at high speed to an electricity generating power station.  Refer to photos in some of my earlier posts such as: Derwent River water passes via the township of Tarraleah .

My typical experience of penstocks, as conduits for water gushing into electricity generating power stations, is of massive steel structures.  I suspect this would be the expectation for others who have seen Tasmania’s penstocks only from the vantage point of our highways.  For people like me, the wooden penstocks feeding Wayatinah Power Station are astounding and therefore I thought it would be of value to undertake some research and learn more. Andrew’s photo below shows the wooden penstocks emerging from an underground tunnel and sloping down towards the Wayatinah Power Station.


The questions which come to mind include, are there any other wooden penstocks in Tasmania, what wood is used, when were they built, why weren’t they built with metal, who built them, how effective are they, and what is their life span. In my research a constant term was ‘stave’. A stave is a narrow length of wood with a slightly bevelled edge to form the sides of barrels, tanks and pipelines, originally handmade by coopers.

After a little research I now know that wooden penstocks are not unique to Tasmania and have been built in a number of countries including Britain, Canada and the USA. For example, wooden penstocks were built for hydroelectric facilities in Lincoln County, Wisconsin, USA as shown in this article.  This web site contains a great deal of construction and other information which I imagine is similar to that for Tasmanian wooden pipelines, and therefore worth reading. The photo below, from that website, shows redwood penstocks at the Thomson Hydroelectric Station in eastern Minnesota, Wisconsin.

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The website answered some of my questions: “Why wood? First and foremost, keep the wood thoroughly wet and it will not rot. If there is an issue, it has to do with the quality of the metal bands. Expansion joints are not required as the wood absorbs the water and expands. Steel restraining bands are used and the wood will expand against those. The metal bands are used only to provide strength. Even when they corrode and lose their strength, the wood will hold together and the bands can be easily replaced. The carrying capacity exceeds that of metal pipe, in large part because the interior walls remain smooth and do not form tubercles. The wood components are easily transported to the sites, which can be remote. No massive hoisting apparatus is needed. They do not require concrete foundations, but “float” on the gravel. The wood is easy to bend, so the contractors can follow a more natural contour; for example, bending around curves. There is no need to cover them. The wood has natural insulation. They can last for 40-50 years. Simple carpentry can be used for repairs. Assembly is easy.

Why do we see so any leaks? Leaks do occur at the end of a stave, at what is called the butt-joint, most often when combined with a breakdown or severing of a steel band at that point. In addition, steel plates are sometimes placed in the slots at each stave end, and these steel plates can corrode. Also, some erosion can occur at the end of a stave, and develop into a hole. In this instance, the steel band in that area might corrode and sever, and the pressure of the water inside might break off a section of the stave, however small. Metal corrosion also sets up a mild acidic condition. The acid can degrade the wood. There can be a breakdown in the staves when the water pressure inside varies a lot. You will seldom see wooden penstocks for example in positions where turbines can vary the water pressure output in large degrees. This creates what is known as the hammer effect which can beat up a wooden penstock quickly. It’s best to try to keep the inside water pressure as even as possible. This said, small leaks can self-repair as the wood expands. Even large breakdowns in the staves can be repaired. In most instances, the leaks are tracked closely and there is very little risk of a catastrophic failure. “

The hole in a penstock and the story of its repair speedily within one week for the Jackson Hydro Station in New England, USA can be seen here. Another rupture coverage, this time in Quebec, Canada is covered here.  I was surprised when this website included photos of other wooden penstocks around the world including a photo of one of Tasmania’s wooden penstocks.  It looks remarkably like Wayatinah’s penstock, and there are outbuildings in view and some dates as well.  Perhaps a blog reader can make a more accurate identification.

It seems there are only two Tasmanian power stations being supplied by water flowing down wooden penstocks: Lake Margaret Power Station (not on the Derwent River) and Wayatinah Power Station.   Wikipedia  explains the situation in relation to the Lake Margaret Power Station here. For more information refer to the fact sheet for Upper Lake Margaret Power Station, the fact sheet for the Lower Lake Margaret Power Station, and a  note regarding Innovation and heritage feature in Lower Lake Margaret redevelopment. Photos of the pipeline can be seen in Lake Margaret Power Scheme A Conservation Management Plan. I found the photos on pages 11 and 19 particularly helpful with pinpointing the location.

In relation to the wooden penstocks feeding the Wayatinah Power Station,  a You Tube video is worth watching. Page 25 of the booklet ‘The Power of Nature’ includes a photo of the woodstave penstocks at Wayatinah. Other informative photos of dams and power stations and penstocks associated with other parts of the Derwent River are also presented.  Most are glamour shots taken from excellent locations and, after the gritty often basic photos which I have taken, these make the extraordinary engineering feats look even more magnificent and significant. This website offers the following information:  “Wayatinah is the sixth station on the Nive/Derwent cascade and is downstream of Liapootah HPP. Water is supplied from a small storage lake called Wayatinah Lagoon and diverted into a 2 km tunnel to two 1.3 km low-pressure wood stave pipelines. Finally, water drops 56 m through three steel penstocks to the powerhouse.”

Now the scene is set for the story of the walk between Wayatinah and Catagunya Power Stations.

The Derwent River near Wayatinah town ship

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Salmon hatchery at Wayatinah on the Derwent

Next to the bridge over the Derwent River on Wayatinah Road, an Atlantic Salmon hatchery owned by Salmon Enterprises of Tasmania Pty Ltd trades as Saltas.

According to the Tasmanian Salmon Growers Association the business was established in 1985 ‘after a report to the Tasmanian Fisheries Development Authority concluded that a salmon farming industry could be successfully developed in Tasmania. As a result, in 1984 fertilised Atlantic salmon eggs were purchased from the Gaden Hatchery (Thredbo River, Jindabyne, New South Wales, Australia), which were from stock originally imported in the 1960s from Nova Scotia, Canada. A sea farm was established at Dover in the south of Tasmania and a hatchery was developed at Wayatinah in the central highlands.’

Innotech Controls claims Saltas is ‘Australia’s largest producer of Tasmanian Atlantic Salmon smolt, supplying over 3.5 million smolt each year to the Salmon farm industry.’  Their website provides details about water temperature management using the water of the Derwent River and Wayatinah Lagoon. ‘At Wayatinah, the water used by the SALTAS hatchery is gravity fed from the River Derwent. During the hot summer months, when river flow is greatly reduced, the water temperature can rise by as much as 10 °C in an 8 hour period. Water temperature in excess of 23 °C can be fatal to the fish stock. Located 1km from the hatchery is Wayatinah Lagoon, a man-made lake that forms part of the State’s Hydro Electric scheme. Research showed that at a depth of 6 metres, the water temperature was consistently between 9 and 17 °C. A project was undertaken to utilise water from the lagoon for temperature control at the hatchery and to provide additional water in times of low flow in the River Derwent. The water temperature is monitored at the hatchery where it is maintained at 16 °C +/- 1 by staging the water pumps at the lagoon.’

A thesis by Anna Do offers ‘SALTAS currently operates two hatcheries: Wayatinah hatchery on the Derwent River and the nearby Florentine hatchery‘. When I walked on the north/eastern side of the river upstream from the Wayatinah Power Station last year I could not identify the buildings near the confluence of the Florentine with the Derwent River. Now I understand that I was looking at the second hatchery.  In this thesis on page 8, an aerial photo of the Wayatinah hatchery shows the Derwent River with considerably more water flowing that exists today. Refer to my photos of a stony river bed earlier in this post.

The marks of man

Lake King William, the electricity transmission lines and their towers, the cleared but regrowing areas surrounding them, and the nearby 4WD vehicle tracks changed the landscape from its original form and I spotted other signs of non-aboriginal intervention in the bush.

As I was closing in on civilisation again, while nearing the town ship of Derwent Bridge, I noticed a felled log beside the track with saw marks.  What struck me as strange was the way more than one straight length of timber had been sawn from within the tree trunk.

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Not a letterbox

When walking through the bush from time to time you see tree stumps with a horizontal man-made slit.  These were not letter boxes for use by the old European settlers.  Rather they were part of the process to fell huge ancient trees. Where I was walking, the trees would have been felled to clear a path for the electrical transmission power lines and the 4WD track.


These notches were made in the days when strong men wielded axes with accuracy and extraordinary bush knowledge. This was before chain saws: the massive girth of many trees would have rendered such equipment useless. In addition, such tree clearings were in an area too remote for massive machinery to access, even if it had existed.

At its simplest, the process can be described as: first the axeman cuts a small slit in the tree trunk then jams a board into the gap.  He (and I have never heard of a woman doing this) jumps up onto that board. Then he creates a new slit higher up the tree, grabs a second board and jams that into the new slit.  He jumps up onto the second board and releases the first board, rests it across the one on which he stands, and then he cuts another slit higher up. The process is repeated until he is sufficiently high to start cutting a 45 degree notch which will help the tree fall in a certain direction.  After a while, the axeman descends and repeats the process up the same tree from another angle, then continues on cutting the notch until the top part of the tree sends signs that it will fall. At this point, in order to stay alive, he jumps down the tree as quickly as he can and moves a distance away being careful not to be struck by any other vegetation or tree than is inadvertently brought down at an unexpected angle.

From this practice has grown the international sport of wood chopping which includes a competition on tree felling.  The image below from the Queensland Archive shows how this looks in the sporting arena.

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Did you know the first wood chopping competitions were held on the north-west coast of Tasmania (not far from where I was born)? These days the competitions have become an international event.  To see how it all works in practice, at least in competitions, I suggest you have a look at a local competition in Canada on You Tube

From the Nile River in Africa to the Derwent River in Australia

The Nile River in Africa and the Derwent River in Tasmania Australia.  On two different sides of the world.

Q.     What connects these two rivers?       A.     Agatha Christie

You gasp.

In 1922, the now-world renowned detective fiction novelist Agatha Christie took herself on a ten-month Grand Tour of the British empire, including South Africa, Australia, New Zealand, and Canada. Previously she had spent time in Egypt with her mother in 1910. Her travels helped flesh out details for many of her ‘who-done-it’ mysteries.

For those of my blog followers who have not been devotees of Hercule Poirot, I recommend you read Agatha Christie’s story of Death on the Nile written in 1937, visit the theatre to see Murder on the Nile the 1944 play based on the novel, or watch anyone of the many films that have been produced based on this story. I would be surprised if you cannot access something on the internet.

The correspondence of her travels has been collated into the publication The Grand Tour: Around the World with the Queen of Mystery.

 Grand Tour Agatha Christie bookcover

In this book we can read “From Australia we went to Tasmania, driving from Launceston to Hobart. Incredibly beautiful Hobart, with its deep blue sea and harbour, and its flowers, trees and shrubs. I planned to come back and live there one day. From Hobart we went to New Zealand.” Agatha Christie is, of course, referring to the expansive harbour on the sea end of Tasmania’s Derwent River.  She was also making a typical mistake that some mainlanders and most international tourists make. Tasmania is still part of Australia, even though it is a large island to the south.  So, when she left Sydney New South Wales Australia, I suspect Agatha sailed into Launceston Tasmania Australia.

A book reviewer at http://www.amazon.com/The-Grand-Tour-Around-Mystery/dp/006219125X: remarked “The Grand Tour is a fascinating collection of never before published letters and photographs detailing Christie’s travels around the British Empire in 1922. Most of the letters were sent to her mother and included photos taken with Christie’s own camera as well as newspaper clippings and various memorabilia. This collection is an insight into the thoughts and mind of a young Agatha Christie who had just published two novels and would later become the most widely published author of all time. She and her husband, Archie, embarked on a year-long voyage as part of a promotional trade mission, so there was work involved as well as various obligations as they visited South Africa, New Zealand, Hawaii and Canada. Her letters to her mother were, of course, candid which for this reader greatly added to their charm. I especially enjoyed Christie’s slightly wicked sense of humour, such as when she describes a fellow passenger as “the only young thing on the ship, but although very pretty, is a terrible mutt.” Her observations of both people and places are acute and fascinating to read.  Mathew Prichard, Christie’s grandson, has done an excellent job of collecting, editing and introducing these letters. We are in his debt for The Grand Tour reminds us that Christie was not only an outstanding author but a remarkable woman as well.”

The back cover of the book records:

“In 1922 Agatha Christie set sail on a ten-month voyage around the world. Her husband, Archibald Christie, had been invited to join a trade mission to promote the British Empire Exhibition, and Christie was determined to go with him. It was a life-changing decision for the young novelist, a true voyage of discovery that would inspire her future writing for years to come.

Placing her two-year-old daughter in the care of her sister, Christie set sail at the end of January and did not return home until December. Throughout her journey, she kept up a detailed weekly correspondence with her mother, describing the exotic places and the remarkable people she encountered as the mission travelled through South Africa, Australia, New Zealand, Hawaii, and Canada. Reproduced here for the first time, the letters are full of tales of seasickness and sunburn, motor trips and surfboarding, glamor and misery. The Grand Tour also brings to life the places and people Christie encountered through the photos she took on her portable camera, as well as some of the original postcards, newspaper cuttings, and memorabilia she collected on her trip.

Edited and introduced by Agatha Christie’s grandson, Mathew Prichard, and accompanied by reminiscences from her own autobiography, this unique travelogue reveals a new adventurous side to Agatha Christie, one that would ultimately influence the stories that made her a household name.”

Writing a blog helps to find others with similar interests

The tags and categories, which I create each time I write a blog, help people during their internet searches to find my blogsite.  Another way in which people around the world find my blog is if they are already using WordPress for their blog. In addition, I have a specialised Facebook and Twitter account for this Walking the Derwent project, and my LinkedIn account also automatically receives the regular postings. So there have been many ways in which my blogs have been found by others and, in some cases, have been just what they wanted to read.

The surprise for me has been the interesting bloggers who have ‘liked’ or commented on my blogs.  When they do this I always check their blogsite and sometimes I become an avid follower because their blog preoccupation coincides with an interest of mine.

The latest great blog find is by Jean Béliveau who decided to walk around the world.  His blog can be examined at http://wwwalk.org/en.  Originally, this extraordinary man left Montreal in Canada and then took 11 years for his walk.

Jean Béliveau’s blog is very well organised so that you can find which towns he visited in each country.  Looking at his itinerary in specific counties, the towns and cities visited are eclectic and not always capital cities or key places. Of course, with a parochial interest, I searched and found where he walked in Tasmania. There was a great deal of my State which he didn’t walk on, but since (like me) he was making his own rules about where to walk, it does not matter. After all, he never said he was going to walk around each country and through each town or city.

Don’t miss his selfie photos on the left of his blogsite because they show his changing looks in each country; hair, skin colour etc.