Showing posts with label Albert Town. Show all posts
Showing posts with label Albert Town. Show all posts

Saturday, August 2, 2014

Conservation Group Aims To Build Unity

Conservation group aims to build unity

A task force has been set up in Wanaka to create more co-ordination and collaboration between the dozens of groups each working on their own conservation projects.

Chairwoman of the newly formed Upper Clutha Conservation Taskforce, Megan Williams, this week told the Otago Daily Times the task force was the result of a public meeting in May held as part of the region's Shaping our Future process.

It was attended by various conservation groups ''just to try and get some vision and strategy around what people were doing and encourage more collaboration'', Ms Williams said.

Data collected from the meeting was being developed into the task force's terms of reference, and a ''draft vision'' was being formed using existing material as a starting point.

''We're just trying to think long-term and lead the groups to develop a shared vision,'' Ms Williams said.
Butterfields Wetlands next to the Hawea River, near Albert Town, had three different conservation groups working on it, ''which haven't actually agreed on what they want the place to look like in the future''.

One group was planting trees and another was planning to build a track.

There were also five groups working in the Matukituki Valley and ''they haven't really been collaborating''.

''So I believe since the meeting in May a group of them have got together ... It's just encouraging a little bit more collaboration there to get more done.''

Long term, everyone agreed on the need for ''pristine water and pristine air'', Ms Williams said.
But the question was how to ensure those things were achieved.

Asked about the prospect of another 1400 woodburners being installed in the proposed Northlake subdivision of Wanaka, Ms Williams said the task force would ''try and stay out of the political process at that level and really try to stay big-picture on conservation issues''.

''All we are looking at doing is leading a discussion with the Upper Clutha groups to develop a shared vision so that everyone can work together.''

It was hoped to have a conservation strategy prepared before the end of the year.

Already it seemed clear more water, soil and air monitoring needed to be undertaken.

''Whether that's done by volunteers or whether we do that by lobbying the local authorities - that's the type of action we will be hoping for.''

Data was needed to establish ''base lines, so that we know where we are at'', Ms Williams said.

The task force would not be taking over the roles of other conservation groups but would be complementing what they did.

Ms Williams, originally from Dunedin, has a background in tourism, and teaches sustainable tourism at the Queenstown Resort College.

The members of the task force are: John Wellington, Robbie Lawton, Anne Steven, Andrew Penniket, Calum MacLeod, Natalie Astin, Alexa Forbes and representatives from the Lake Wanaka Guardians and Department of Conservation.

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Tuesday, August 13, 2013

Albert Town Hit Hardest If Dam Fails

Albert Town hit hardest if dam fails
By Sarah Marqet, on Tuesday 13 August 2013
Otago Daily Times

If the Lake Hawea Control Dam were to fail, up to 420 properties and 2620 people could be affected, a Contact Energy-commissioned report says.

The September 2011 report outlines potential consequences of a dam failure and was required as part of the energy company's standard practice, not because of any concerns with the dam.

It has been made public now due to its inclusion in the agenda for the Clutha Management Committee meeting on Friday.

Albert Town, situated at the confluence of the Hawea and Clutha Rivers, would be the town most affected, with possibly 158 to 230 properties, two hotels and a campsite flooded.

However, providing a breach of the dam was noticed when it first happened, there would be a three-hour window before the flood waters reached the town, allowing time for evacuation.

Depending on initial water levels in Lake Wanaka, there could also be extensive damage through Wanaka town with 60 buildings, including hotels, cafes and a supermarket, affected.

Because of the large storage capacity of Lake Wanaka, it would be three days before the peak level was reached.

Three bridges across the Hawea and Clutha Rivers would probably be destroyed by the flood but the one on State Highway 8B at Cromwell would not.

The ''flood wave'' travel time from Lake Hawea to the upper reaches of Lake Dunstan would be seven hours, allowing plenty of warning time for Contact Energy to increase the flow of water through the Clyde Dam to lower the level of the lake.

The Clyde Dam is 94km downstream of the Hawea dam.

Water would flow over the top of the Clyde Dam (overtopping) for up to 26 hours, but it had been designed to withstand this.

Severe bank and river bed erosion could occur, as could deposits of debris due to the ''heavily wooded banks''.

The report, by AECOM New Zealand Ltd, used two dam-failure scenarios - an earthquake-induced failure and a failure induced by high lake levels following a ''probable maximum flood event''.
It was the latter failure that would cause the most damage.

The Lake Hawea Control Dam is an earth-fill dam. The report says failures of that kind of dam are ''extremely rare but have occurred in the past as the result of internal erosion or overtopping''.

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Thursday, November 29, 2012

New Cycle Track Adds To Network

New cycle track adds 12km to network
By Cris Johnston, on Thursday 29 November 2012
Otago Daily Times

The Upper Clutha's network of walking and cycling trails will be officially expanded at the opening of the Newcastle Track on December 8.

The formalities will take place at the Albert Town end of the track on the true left of the Hawea River, over the Hawea River swing bridge, at 10am on Saturday, December 8. Riders and walkers will then be encouraged to cycle or walk the 12km track, which runs along the true left of the Clutha River.

The Upper Clutha Tracks Trust will hold a sausage sizzle from 11.30am at the other end of the track at the new car park on Kane Rd, just north of the Red Bridge at Luggate.

The Newcastle Track provides greater access to the Clutha River and has spectacular views, including the conservation area Rekos Point near Luggate, from the terrace above the track.

The track is named after the planned settlement of Newcastle, which was surveyed on the other side of the Clutha River from lower Albert Town, but never developed.

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Friday, May 27, 2011

Luggate Walking Track Opening

Walking track to open this Sunday
By Marjorie Cook, on Friday 27th May 2011
Otago Daily Times

The Upper Clutha Tracks Trust project has been done in consultation with the Luggate Community Association, Department of Conservation, Wanaka Community Board, Contact Energy and other groups.

New Luggate Creek Track Bridge 

It is an extension of the Upper Clutha Track that begins at Albert Town.

Walkers and cyclists can now travel below the Luggate Red Bridge to the Nook, across a new bridge over the Luggate Creek and up to Luggate township, finishing a short distance from the Luggate Hotel.

"It's now truly pub to pub," trustee John Wellington said of the trust's trail network, which also includes Wanaka, Albert Town, Cardrona and Lake Hawea.

With Luggate now on the trail, just Hawea Flat and Makarora are out of the loop.

But the trustees said they were trying to think of ways to eventually link those townships to the network, plus extend the Luggate track down to the Queenstown Lakes District Council boundary at Queensberry.

Mr Wellington said the idea for the Luggate Creek extension was formed before the Upper Clutha Track between Albert Town and the Luggate Red Bridge had been completed.

Initially, the trust had wanted to cross the bridge and continue the track downstream on the Tarras side of the Clutha River.

That changed when the trust and association met to discuss access to the Nook, a whirlpool in a bend in the Clutha River.

Devil's Nook from Luggate Creek Track

Central Otago track advocates are also working on trails with the goal of a track all the way to Cromwell, Mr Wellington said.

Another Upper Clutha Tracks Trust concept is to complete a loop back from the Luggate Red Bridge to Albert Town on the true left of the Clutha River.

Mr Wellington said the trust was in the very early stages of developing that proposal and had to first negotiate with landowners, including Contact Energy.

"There is public land all the way up but we will have to also talk to neighbours," Mr Wellington said.

The Luggate Creek Track has cost about $100,000 to build so far, with the Department of Conservation and contractor John Sutton contracted to do parts of it.

That is not a final figure because the extension below the Nook has not been completed.

There is a new bridge across the Luggate Creek near the Nook.

The opening of the track will be celebrated at 10am on Sunday. Signposts explaining how to get to the track will be put on State Highway 6 at Luggate.

More...

Wednesday, April 13, 2011

Drilling At Luggate Site

Drilling at Luggate site
By Matthew Haggart, on Wednesday 13 April 2011
Otago Daily Times

Contact Energy is undertaking a drilling project near Luggate to investigate whether geological conditions are suitable for the construction of a hydro-electric dam on the Clutha River.

Upper Clutha River and Reko's Point Conservation Area,
threatened by Luggate dam

Contact Clutha hydro project manager Neil Gillespie, of Cromwell, said the geotechnical investigation and drilling programme did not indicate Luggate was the preferred option.

"The purpose is to gain more information on the geological conditions there. Currently, we have much greater detail on ... conditions at the other three possible sites [Queensberry, Beaumont and Tuapeka Mouth] than we do at Luggate and we want to gain a comparable level of information for all four possible future options," he said.

In 2009, Contact dusted off decades-old plans for Clutha River hydro-electric schemes, deciding to revisit options for the four potential dams.

The company has spent the past two years investigating the options at the four potential sites and consulting communities, amid opposition from Clutha River protectionist groups.

Mr Gillespie said a drilling rig was scheduled to begin exploratory testing to a depth of up to 30m at a site about 2km below the Luggate Red Bridge.

Upper Clutha River Guardians president Tim Ryan, of Wanaka, questioned the need for further investigation at Luggate when Contact had resource consent to install hydro-electric turbine generators at Lake Hawea.

"It is of major concern to us. Why aren't we seeing anything being built at [Lake] Hawea? Why do they have to go and investigate an area where a dam would destroy the whole valley back to Albert Town?" he said.

Mr Gillespie said there was still no expected time-frame for work to begin on installing turbine generators at Contact's Lake Hawea storage gates that would be capable of providing 17MW of electricity.

"Detailed" design plans were "yet to be completed", which would provide an outline for when construction might start.

However, Mr Gillespie did not know when those design plans for the consented turbine generators might be completed.

Clutha Matau-Au River Parkway Group chairman Lewis Verduyn, of Wanaka, said the Luggate dam proposal, "like all of Contact's old plans for large dams on the Clutha, is too destructive, too backward-thinking and too problematic".

Drilling was being carried out at the site to see if there was suitable bedrock capable of supporting large-scale foundations.

"They are doing their homework to further investigate costs associated with building dams. If there is no bedrock there, they may not be able to proceed because it could prove too costly," he said.

He also questioned the need for a dam, which, at nearly 1km wide, would have a profile across the Upper Clutha Valley "larger than the Clyde dam" and yet would generate only 86MW.

Mr Gillespie had consulted the River Parkway Group about its "geotechnical investigations" but "nothing I have learned about [their options] has made me feel better about the project", Mr Verduyn said.

Contact has already carried out preliminary digging at the drilling site, which is near where the Luggate Creek enters the Clutha River at the popular scenic area known as the Devil's Nook.

Mr Gillespie said pits about 4m deep had been excavated to check ground conditions before the holes were refilled.

The drilling-rig crew was expected to begin work after Easter, putting down six drill holes to depths of 10m-30m, during a projected three-week operation.

An ensuing geotechnical report about the potential site would be considered and would enable a clearer picture of possible costs of building a dam, he said.

The four sites:

Luggate: 25m-high embankment dam, located about 2km downstream of Luggate Red Bridge, creating 350ha lake extending 15km to near Albert Town.

Queensberry: 14m-high embankment dam to feed into either a 12km or 9.5km-long canal to down-river powerhouse, creating 240ha lake extending 9km up river to near Luggate.

Beaumont: 30m-high concrete gravity dam located about 2km from Beaumont township, creating 1100ha lake extending 29km upstream from dam.

Tuapeka Mouth: 50m-high concrete dam located about 2km upstream from Tuapeka Mouth, creating 3200ha lake extending 55km upstream to Millers Flat and flooding Beaumont township.

More...

Tuesday, June 29, 2010

Riverrun Trail Series To Promote Tracks

Riverrun Trail Series to promote new tracks
Tuesday, 29 June 2010, 10:50 am
Press Release: eveNZ

A new trail running series designed to showcase the spectacular location of Lake Wanaka’s tracks and trails was today announced by the team behind the successful Challenge Wanaka triathlon.

The inaugural Riverrun Trail Series aims to encourage an active lifestyle and enjoy the recently developed tracks in the Lake Wanaka region: the Hawea River Track, the Upper Clutha River Track and the Damper Bay/Waterfall Creek Track. For all three races competitors will be treated to amazing scenery along a river or lakeside trail.

The Riverrun Trail Series provides people with the perfect opportunity to explore the new tracks in a fun and safe environment, with prizes for place getters and plenty of spot prizes to encourage wider participation. Runners can enter individual races or all three and compete for The John Pawson Trophy.

The Riverrun Trail Series begins 17 October with a 5km, 10km and half marathon option on the Hawea River Track. Race two on the 19 February 2011 is a 14.1km run from Albert Town to Luggate on the Clutha River Track with the final race on the 21 May from Glendhu Bay to Wanaka’s Roy’s Bay via the Damper Bay and Waterfall Creek Track, 14.3km.

Race director Victoria Murray-Orr is excited to be staging the series and is committed to encouraging new participation into running as well as further enhancing Lake Wanaka’s reputation as a sports destination.

“Creating a series encourages people to stay fit and healthy throughout the year and to set personal goals. We hope the events will appeal to serious runners as well as those looking for a social morning out with friends and family,’’ she said.

The event is delighted to have the support of Riverrun and the Pawson Adventure Fund as naming sponsor. Offering a high standard of accommodation and spectacular mountain views, Riverrun lodge is surrounded by 500 acres of farm land bordering the Clutha River and the trails incorporated in the series. The late John Pawson, co-owner of the property was passionate about the outdoors and instrumental in the development of the tracks with the Upper Clutha Trails Trust.

“I am very happy to be involved with this fantastic new event which makes such great use of the network of tracks opening up to us. John was always keen to get out and enjoy the amazing countryside Wanaka has to offer and I am looking forward to being on the start line in October!” said Riverrun owner Meg Taylor. “It is nice to have an easily accessible, post-winter race to aim for.”

Developing the tracks has been an ongoing project for many years with multiple organisations working together including the Upper Clutha Trails Trust, Queenstown Lakes District Council, Department of Conservation, Te Araroa Trust, Clutha Mata-Au River Parkway Group, adjoining landowners and with additional funding from Central Lakes Trust, Otago Community Trust, NZTA, and the Wanaka Walkers Trust.

The Riverrun Trail Series is created, promoted and staged by EveNZ Consultancy. For further information please visit www.trailseries.co.nz

More...

Thursday, May 6, 2010

Contact Decision Not Likely This Year

Clutha hydro decision not likely until next year
By Cris Johnston, on Thursday 6 May 2010
The Southland Times

It could be next year before Contact Energy makes a decision on future hydro-electric development on the Clutha River.

The company publicly revealed details of plans to reinvestigate four potential new dam sites at Luggate, Queensberry, Beaumont and the Tuapeka Mouth in 2008.

Initial consultation included the set up of a website for public comment about the proposals estimated to cost between $300 million and $1.5 billion.

Contact Energy hydro manager Neil Gillespie said yesterday the company had envisaged making an announcement on its preferred choice "about now" but there was still a lot more work to do.

"You could say a decision is still some time away – it could be late this year or even into next year, I am loathe to put a time on it," Mr Gillespie said.

"At this stage there is no preferred option."

During the past year he had met community representatives from the four areas and last month attended an inter agency meeting held by the Guardians of Lake Wanaka where the proposal for the Luggate dam, the smallest of the four options was discussed.

Aware of concerns about the proposed dam Mr Gillespie said constraints of the Lake Wanaka Preservation Act meant the level of the Luggate reservoir would not be able to exceed 271m above sea level.

Enacted in 1973 the Act prevents control of Lake Wanaka levels and the natural flow of the Clutha River between its source at the lake outlet and its confluence with the Cardrona River. "Nothing can breach that Act. With the Luggate option we would have to comply with the existing piece of legislation. The Luggate dam was consented in the late 1980s under the same constraints," he said.

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Saturday, March 27, 2010

Enthusiasm For Clutha River Track

Enthusiastic response to Clutha River Track
By Marjorie Cook, on Saturday 27 March 2010
Otago Daily Times

A new section of the Clutha River Track will be officially opened at 10am today at Pawson's Crossing, Albert Town, but the track is already being used by large groups of cyclists and walkers.

The Upper Clutha Tracks Trust and Department of Conservation recently finished the 2.5km section linking Albert Town to Stevenson's Rd. There the track joins Reko's Point track to Shortcut Rd at Luggate.

Cyclists Roger and Sandra Cain, of Dunedin, were this week enjoying the track with friends for the first time and they all gave it a rave review.

The track was "excellent", "very well done" and "a great idea", they said.
The track's completion means people can now undertake an off-road cycle or walk of about 25km from Wanaka's lakefront to Luggate, following the lake shore and Clutha River all the way.

An off-road trip of similar distance is also possible from Lake Hawea to Luggate.

The new section of the Upper Clutha River Track was completed for $65,000.

It is the most challenging part of the track and traverses the Halliday Bluffs for 500m before rising on to natural terraces above the river.

Funding is being sought to continue the track to Luggate Creek.

Eventually, it will form part of the Clutha Mata-Au River Parkway from Lake Wanaka to Balclutha.

The Upper Clutha Tracks Trust will celebrate the opening informally at Pawson's Crossing - the new bridge across the Cardrona River just up from the confluence with the Clutha.

The public is invited to join in and then walk or bike along the track.

Among those attending today's opening is Alexander Reko Hesselin (known as Mick), who is a descendant of the Maori chief Reko, who in 1853 guided the first European, farmer Nathaniel Chalmers to Wanaka.

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Third Leg Of Clutha River Track Ready

Third leg of Upper Clutha River track ready
By Cris Johntson, on Saturday 27 March 2010
Southland Times

A descendant of Maori chief Reko who in 1853 guided a farmer to what is believed to be the first European sighting of Wanaka will be the guest of honour at the opening of the Upper Clutha River track this morning.

The 13km track from Albert Town to Luggate's Shortcut Rd is the third in a series created by the Upper Clutha Tracks Trust and was constructed in conjunction with the Department of Conservation.

It completes the network of tracks from Glendhu Bay and Lake Hawea to the Clutha River and through the Rekos Point Conservation Area to Shortcut Rd.

DOC Wanaka area manager Paul Hellebrekers said the track had a rich history dating back to early Maori exploration followed by a period of goldmining and farming.

Chief Reko guided Clutha district farmer Nathaniel Chalmers over an inland route from Otago arriving at what is now the track site.

An area along the cycling and walking route "Rekos Point" had been named after the guide. A descendent, Alexandra (Mick) Reko Hesslin would attend the opening as a special guest, Mr Hellebrekers said.

Mike Allison of the Central Lakes Trust, one of the key funders of the project will perform opening ceremony duties.

"The opening of this track is made possible thanks to the patience and determination of members of the Upper Clutha Tracks Trust," Mr Hellebrekers said. "Their foresight in undertaking this project in conjunction with the department is a real conservation and recreational gain for the region. "I hope many people will take the opportunity to get out and enjoy it."

Today's opening ceremony will be held at 10am at Pawsons Crossing Bridge on the Cardrona River at Albert Town. Access is from Kinneberg St.

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Thursday, October 8, 2009

Clutha River Trail Network Grows

Trail network growing legacy
By Matthew Haggart, on Thursday 8 Oct 2009
Otago Daily Times

A new bridge is guided into place at the Cardrona River mouth yesterday at the starting point for the planned Clutha River trail. Photo by Matthew Haggart. The expanding network of trails and cycleways across the Upper Clutha is providing a valuable infrastructural asset for both tourism and local communities, Wanaka woman Meg Taylor says.

She made the comment on the day a bridge was laid across the mouth of the Cardrona River.

The bridge will be named after her late husband John Pawson, founding chairman of the Upper Clutha Tracks Trust (UCTT).

Mr Pawson died in a climbing accident on Mt Aspiring last November, but the ongoing work of the UCTT is blazing a trail as part of his legacy.

Ms Taylor thanked the parties involved with the construction of the new bridge, a $50,000 joint project by the UCTT, the Department of Conservation, and Hawea Flat building outfit CBG Quality Construction.

Although she had not decided on naming the memorial bridge, she was "leaning" towards a title of "Pawsons Crossing".

The new bridge is located at the foot of the Halliday Bluff, near Riverrun, a tourism lodge established by the couple, at the start of a planned 7km trail connecting Albert Town and Luggate.

Walking on trails and tracks was the most common activity undertaken by people staying at Riverrun, and also tourists to Wanaka, Ms Taylor said.

"Whether it's a riverside stroll, a lakeside amble, or a walk to a glacier, it's something nearly everyone does when they come here."

The quick succession of new trails being opened around the district was phenomenal, she said.

"I'm chuffed with it and I know John would be, too," Ms Taylor said.

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Clyde Dam Highly Problematic

Since the filling of the Dunstan reservoir behind the Clyde dam was completed in 1993, the Clyde dam controversy has faded in the minds of most New Zealanders. But the woes of the last 'think big' project have not gone away. Despite extensive and costly mitigation measures, issues remain regarding gorge instability, faultlines, and reservoir sediment build-up.

The Cairmuir-Dunstan Fault cuts across the gorge just above the dam, and the River Channel Fault disects the dam and the powerhouse. The discovery of the River Channel Fault came as a surprise to dam workers, who uncovered the micro-fractured rock running in a wide band along the riverbed. Obviously, fissured rock is not suitable for dam foundations. The first solution was to pump vast amounts of slurry concrete into the fault, but concerns mounted over the extent and depth of the faultline, and the likely futility of 'dental' concrete.

Finally, experts were called in to determine the extent of the fault issue. It was calculated that the River Channel Fault was 12-15km deep. This lead to a dam re-design in 1982 (during which a sluice channel was omitted leading to later modifications that reduced the dam's MW output by one-third). Subsequent investigations carried out by a team of some 40 geologists revealed serious instability issues throughout the gorge. The result was an incredibly expensive gorge stabilization programme, costing $936 million dollars (2005 value), resulting in the total cost of the project blowing-out to $1.4-1.8 billion dollars. The exact cost is unavailable or unknown, suggesting the true cost could be even higher.

There was considerable doubt over whether or not the dam would be safe, but in the end the government of the day, under Prime Minister Robert Muldoon, refused to admit that the project had been botched, and it was finished, complete with a controversial 'slip-joint' to accommodate earthquakes up to, supposedly, 7 on the Richter Scale.

The 'slip-joint' was hailed as an engineering achievement, but one of New Zealand's most respected geo-technical scientists at the time, Gerald Lensen, insisted that it was designed incorrectly, because the River Channel Fault is 'tensional' (pulling apart) and not 'lateral' (slipping sideways). Needless to say, this fact has been kept quiet ever since.

Now, according to GNS scientists, the 'big one' is overdue along the Alpine Fault (bigger than the 7.8 Fiordland quake in July 2009). Meantime, the 6,500 measuring and monitoring stations quietly observe the landslide movements, reduced but not stopped, and visible silting up continues in the Kawarau Arm at an alarming rate estimated to be 1.46 million cubic metres per year, building up the reservoir bed profile by an estimated 1.85m annually.

The Decline of Large Hydro

In the 21st century, energy that is "renewable" is defined as energy from a source that is both naturally replenishing and environmentally safe and sustainable. The term “new” renewable energy has also been used to define the latest wave of renewable technologies that are truly environmentally sustainable.

By such standards, hydropower over 10 MW is no longer considered renewable because the negative impacts of large hydropower outweigh the so-called renewable benefits, which have inherent limitations.

In New Zealand, we are told that to maintain our present society and standard of living we need a minimum increase in power availability of 2.5% per annum (peak power), with 170 MW of new generation added each year. Based on this figure, we would need the equivalent of one Luggate dam (86 MW) every 6 months, or one Tuapeka dam (350 MW) every 25 months, or another Clyde dam (432 MW) every 29 months. Clearly, this is not a credible long-term solution.

World-wide, large hydropower declined in the 1990s because of mounting opposition that culminated in the World Commission on Dams report (2000), which acknowledged that large dams do not meet best practice guidelines in the water and energy sector. The global recession spurred more large dam projects, especially in developing countries, but the tide has turned and large hydro is again in decline as new renewable technologies sweep the world.

The intrinsic problems associated with large dams have long been glossed over. Hydroelectricity is often falsely promoted as cheap and reliable. While the operating costs of hydroelectric dams can be relatively low, their construction costs are extremely high, running into the billions of dollars for major projects. They are also prone to cost overruns. The WCD (World Commission on Dams, 2000) found that on average dams cost 56% more than forecast. And 55% of the hydroelectric projects studied by the WCD generated less power than planners promised.

New Zealand's Clyde dam is an obvious example of disastrous cost overruns. According to the public record, the 1982 winning bid from the joint venture of W. Williamson & Co. of Christchurch and Ed. Zublin AG of Stuttgart, was $102.6 million. Ten years later when the dam began producing power, the cost had climbed to $1.4 – 1.8 billion. Conversely, the planned generation of 612 MW had fallen to an actual capacity of 432 MW.

Typically, construction and mitigation costs are under-estimated, long-term costs are ignored, the value of the proposed dam and mitigation measures are inflated, while the value of the current and potential benefits from the existing environment are under-reported.

The proponents of large dams also invariably claim that large hydropower is "green" energy. However, the carbon footprint of a large-scale hydro project is anything but "green". A comparative study at the University of Auckland found that large hydro has a full-life carbon footprint that is 2.5 times larger than that of tidal energy.

A similar comparative study in the U.K. found that in terms of grams of CO2 equivalent per kWh of electricity generated, large hydro in the U.K. comes in with a carbon footprint 2 to 6 times larger than that of wind power. Specifically, large hydro has been measured at 10-30gCO2eq/kWh while wind has been measured at only 4.64gCO2eq/kWh, the lowest except for nuclear (Carbon Footprint of Electricity Generation, 2006).

It is easy to understand why large dams rate so poorly. For example, the Clyde dam contains 1 million cubic metres of concrete, equivalent to about 3 million tonnes. Manufacturing one tonne of cement requires 4.7 million BTU’s of energy, which is the amount contained in about 170 litres of oil or 190 kilograms of coal. Obviously, this combined with emissions from machinery involved in earthworks for foundations, roading, terrain forming, landslide mitigation, and through the loss of river corridor carbon sink forests or vegetation, adds up to an enormous carbon footprint.

There are over 54,000 large dams in the world, some 5,000 of which are over 50 years old. The typical design-life of such dams is 80 years, and an increasing number of old dams are being classified as high risk. It is a telling fact that more dams are being decommissioned than built in the U.S., but dam owners typically avoid decommissioning issues and try to evade the considerable costs associated with dam removal and river restoration. This scenario points to a looming dam safety crisis.

In the past, the benefits of large dams were viewed as outweighing their obvious short and long-term environmental impacts. That has changed.

Large hydropower once represented the epitome of 20th Century technology and a passport to prosperity, projecting a misguided belief that Nature could be controlled without consequences. In the 21st Century, we face a new reality, for which 20th Century energy solutions are unacceptable.

Roxburgh Dam Decommissioning?

The Roxburgh dam was commissioned in 1956, and it is New Zealand's oldest concrete gravity dam. Such dams have a design lifespan of 80-100 years, but the actual lifespan of a dam depends on the rate at which its reservoir fills with sediment. Assessing the remaining life of a dam and reservoir is complex, but reservoir flooding events indicate that time is running out.

When other issues are added to the picture, questions must be asked.

The Roxburgh dam - like the Clyde dam, has faultine and landslide issues that are potentially catastrophic (something which has been kept quiet). However, when the Roxburgh dam was built, there was minimal geotechnical investigation and mitigation undertaken, despite obvious evidence of major landslides in the Roxburgh Gorge, notably at Island Basin.

But reservoir sedimentation is the most problematic issue. In fact, within 15 years of the dam's commissioning, the dam's two low level sluice gates were inoperable, and since then the silt burden has filled much of the Roxburgh reservoir reaching back to Alexandra. In 1995, ECNZ estimated that 1.5 million cubic metres of silt had entered the Roxburgh reservoir every year before the Clyde dam was built, and that a total 50 million cubic metres of silt had accumulated in the reservoir, raising the bed profile 'considerably'. Attempts to 'flush' the silt have had little effect, and have not reversed this process. This is probably because of the 'Gates of the Gorge,' a narrow bottleneck just below Alexandra.

As a result, Alexandra has become flood-prone, and has installed flood defence walls along the river. But even these will not be high enough to prevent future flooding, because the riverbed will gradually keep rising. It was thought that by building the Clyde dam that this sedimentation problem would be largely solved, but some silt still gets through to continue choking the reservoir and river, and the Manuherikia River still contributes silt when it is high.

Efforts continue to "buy time" for the Roxburgh dam. More "flushing" will only move some of the sediment load further toward the dam. (Flushing has failed to remove sediment wherever it has been tried, including on the Colorado.) Physically removing millions of cubic metres of sediment is not practicable because of the costs involved. An interim measure is to remove some sediment from the Manuherikia confluence, and also from the Galloway area, but this does not address the major constriction at the 'Gates of the Gorge.'

The most desperate strategy is to raise the operating level of the Roxburgh reservoir, and this was done in 2009 when a rise of .6m was consented. While this allows water to reach the dam more easily, it also increases the risks associated with flooding events, both at Alexandra and the dam. In the life cycle of a dam, this is the "Russian roulette phase."

The dam owners and the Crown must face up to the fact that the Roxburgh dam and reservoir will not last forever, and that enormous risks are imposed on communities in the meantime. A feasibility study is needed to determine the most effective decommissioning and de-silting methodology. Where such dam removal projects have been undertaken overseas, the costs as a proportion of construction, range from 35% to 150%.

However, since there has been no provision for the ultimate decommissioning of the Roxburgh dam (typical of the hydropower industry), there is something of a head-in-the-sediment policy on this issue.

Questions should be asked, including the most difficult question of all ... when the time comes to decommission the dam, who will pay?
© Clutha River Guardian 2009-2015