Tell us we misheard it…


ODT’s Barry Stewart on Channel 9 News highlighted stories appearing in Tuesday’s newspaper. First mention before we fainted was… No, we really must have misheard it.

Dunedin City Council has voted to [defer?????!!!!!] work on the second stage of the Tahuna Wastewater Treatment Plant.

We ran the DVD back, it did sound like THAT word.
WHY. It can’t be true.

### ODT Online Tue, 24 Nov 2009
DCC may defer Tahuna work
By Chris Morris
The Dunedin City Council looks set to delay part of the planned $74.3 million stage two upgrade to the Tahuna wastewater treatment plant. Council staff have recommended aspects of the plant’s upgrade associated with the processing of solid materials be deferred for two years, while wastewater treatment upgrades proceed as planned.
Read more

Posted by Elizabeth Kerr


Filed under Construction, Economics, Politics, Project management

30 responses to “Tell us we misheard it…

  1. Phil

    Well, I’m not sure that DCC CAN defer the second stage of the upgrade. That second stage is a condition of their Resource Consent obtained from the ORC for the Discharge to Water. A consent which expires in 2011, I believe, having already been extended previously. That means that a new system has to be in place and operational by 2011, not just started in 2011. The only way the upgrade can be deferred, is with the consent of the ORC. And I know that the ORC are adamant that the required works be carried out on time. At least, they were.

    Maybe the DCC has told the ORC that they might struggle to repay the ORC stadium funding if they also have to pay for the sewerage treatment upgrade at the same time? There’s a good conspiracy theory.

  2. David

    Perhaps the new stadium will have to be used as a holding pond until the new resource consent allows discharge again.

  3. Phil

    I noted a while back that there was a “Registration of Interest” announcement posted by DCC for the detailed design and construction of Stage Two. Applications close mid December I think. You would hope that they are not about to waste people’s time. Even Registrations of Interest are not free to prepare. Not to mention the issue of good faith.

  4. Phil

    Ok, that doesn’t read as being QUITE so bad. The discharge to water consent conditions are still being complied with. That’s the big ticket item. Option 3 was never going to fly. Chlorination “shudder”. What’s next, leeches ? I don’t know if there is any ORC requirement for the upgrading of the solid waste disposal at the Green Island landfill site.

    • Elizabeth

      On 20 November (completely unconnected to the news in this thread), I tweeted #SolrayEnergy.

      New Zealand’s Solray Energy Ltd processes sewage algae to make renewable crude oil that’s a genuine replacement for fossil fuel petroleum… Read more at

  5. Richard

    So, as the report confirms either Barry Stewart got it wrong or you misheard.

    ISCOM passed the recommendations today as set out in the report. When formally confirmed by council on 14 December (which is a formality given that all councillors are on ISCOM and the vote was unanimous), the installation of Secondary Treatment of the liquid discharged to sea by the new outfall (which is what everyone generally means when they talk of Stage 2) will go ahead on schedule to produce UV treated wastewater by 1 September 2011.

    The disposal/treatment of the solids generally referred to as ‘sludge’ is all that is being put on hold. At the moment it goes to landfill but the rapid development of new technology with the options of using this e.g. to generate energy, makes that a sensible decision, one that may prove less costly and be environmentally sound.

    I cannot see how the report and the recommendations – now resolutions – can be read any other way.

    No doubt, someone will though. Especially those who immerse themselves in the stuff, day in day out!

  6. Richard

    The Solray Energy project using algae to make something like bio-diesel was on (I think) ONE NEWS or CLOSEUP last week.

    It is not the only evolutionary process being developed in this field but is certainly an interesting one from several angles.

    Europe and the UK face massive challenges in disposing of waste generally and further landfills are, for the most part, a decreasing option.

    Here again, new processes are emerging and hopefully they will be viable and cost affordable by the time we have to deal with the closure of the Green Island Landfill.

    • Elizabeth

      Richard, that was to do with their systems technology patenting, on the news. The point about Solray Energy’s technology is (to note, we aren’t talking “biofuel” here in the accepted sense), they say:

      “our team of scientists and engineers have given the company a unique proposition with proven scaleability that produces long carbon chain length transportation fuels, including Jet-A, high-octane petroleum and diesel”

      So when Solray Energy superheat the algae from wastewater sludge (any sort of algae can be processed through their system), they are correct in saying they are producing CRUDE.

  7. David

    Richard says “I cannot see how the report and the recommendations – now resolutions – can be read any other way.

    No doubt, someone will though. Especially those who immserse themselves in the stuff, day in day out!”

    Richard, I hope you are talking about the paper work, rather than the topic at hand?

  8. Phil

    The recommendations of the report are clear enough. I hope that the extra time doesn’t permit dust to settle under the process. It’s another chance to light up Dunedin’s name as a future thinking leader. If the stadium turns out not to achieve that goal.

    Biogas produced overseas from human waste is typically about 1 dollar cheaper per litre at the pump. I don’t know what the capital costs are. But it’s not a complicated process, simply heat and then leave to ferment for a couple of weeks. Even quicker if you can remove the liquids from the solids at the source, but that’s not feasible with our current reticulation system. Although there’s no reason why it couldn’t form part of the requirement for new subdivisions, having a communal liquids disposal tank for a community.

    There’s the enticement to industry, with the option of a cheaper sustainable fuel source and no pesky Emissions Trading Scheme concerns.

    The high nutrient content of solid waste is also the ideal agricultural fertilizer, and chemical free. That would involve a mindset change on the part of the consumer, but how many of us know that we’re not eating imported food already that has been fertilized the same way?

    • Elizabeth

      Awaiting ODT’s take on the story, in print.
      Any ODT staffer on Ch9 News has only a fraction of time to acquaint the next-day features, it’s pretty ad libbed ‘off the bullet points’. Defer was probably a reasonable term (perhaps not best) to use in the ‘headlining’, given that under Option 2, one part of the exercise needs more work – in sight of the deadlines to have Stage 2 completed. Although Barry was giving us a bald chaser, without any detail needed if to sell papers!

  9. Richard

    Oh the humour David and Elizabeth…..

    David hopes I am talking about ‘the paper’ ……
    ‘Barry giving us a bald chaser’.

    The best one in the papers before yesterday’s ISCOM related to ‘Speed Limits’: Mold Road (Middlemarch): “Shorter then 800km/h but notable change in environment coming from Cemetery Road”. The imagination runs wild. I cannot help thinking that this could be the site for another of George Romero’s NIGHT OF THE LIVING DEAD movies? Is one being shot in secret? Maybe the ODT or the young upstart, D Scene, can find out what lies behind this mysterious comment!

    Seriously though, the huge reduction in the cost of the Allanton WW Scheme of nearly $1m was the good news. Shows what happens when you look for options and get the technology right.

    It has alway concerned me that few, if ever, question this given high capital costs of water and wastewater projects on which we have – and are spending millions – and which will continue to drive increases in rates. It seems to be, “well, Council knows best” or “we cannot challenge the engineers” or (perhaps more accurately) “who cares” etc.

    Calvin was one of the few from outside Council to question”Rolls Royce” solutions. That we were in total agreement on that is probably enough of a surprise for one day!

    Since I successively challenged and had ‘canned’ the replacement of the Kenisngton Gasometer in 1981 in my first term on Council, I have consistently advocated that options should always come to council and the public for consideration, not just the one that staff prefer. And that we must be careful not “to lock ourselves in” until those have been fully explored. That is more important than ever given the rapid advances in technology over the past two or three years.

    As the Allanton case proves. Same with dealing with the solids at our wastewater plants.

    So, you will gather that I welcome and support the positive change in approach that is occurring in the WWW team led by John Mackie. I am not alone in that!

    Now I am not listed in ‘Deaths’ this morning, so I will go and have brekkie!

    Enjoy the day!

  10. David

    Richard, coincidentally in another life nearly 30 years ago our engineering class did a project that designed a potential water and waste water system for Allanton.

    However there’s probably very few people who comment on waste water systems because everyone knows they need one, but few people know enough about the subject to be able to comment.

    Whereas everyone is an expert on the stadium, and how much we need it.

  11. Richard

    Mm…hh. Of course!

  12. David

    Yes, that last comment was intended to be tongue-in-cheek.

    However most people probably are experts on their own circumstances and that of their friends, in regards to how often they would expect to visit the new stadium.

    In the early 2000s, when rugby attendance was at its peak, the DCC did a survey to see how many citizens had gone to Carisbrook over a year. Result – 75% of Dunedin citizens had not gone.

    Since then Rugby attendances have dropped by half to three quarters.

    The stadium is clearly being built for a very very small number of regular attendees.

  13. XXX

    How many people do a crap in Allanton?

  14. Hi Richard,
    Speaking of ‘Rolls Royce’ solutions you may remember I wrote a paper which was published in the ODT in 2004 on the matter of Tahuna’s sludge separation/disposal problems. It of course went nowhere, not even commented on by anyone in or near council. For what it is worth here it is again.


    The reason for producing this paper is to express real concern about the current proposals to extend the pipe outfall to discharge basically untreated sewage into the ocean. The fact that this discharge will contain large amounts of unseparated non sterilised solids suggests that this, and this alone is the prime reason for the 1100 metre pipe extension request.

    This conclusion is further reinforced by the fact, that it has been stated by staff, that, when the second stage is commissioned to meet the parameters set by the ORC, then there will be a further complication of how to dispose of the almost doubling of the recovered sludge. Proof that half of the sludge is presently to go to the ocean.

    Why is it that the sludge is not being more extensively separated at the present time? Well, it would appear that this is caused by several factors, not the least of which is that there could be a fundamental flaw in the original design of the Tahuna Treatment Station which was built and commissioned in April 1981. This is to do with the design and function of the sedimentation tanks which are to facilitate the settling and separation of the solids in suspension. This process is a function of flow rates and time. The flow rates must be sufficiently slow and laminar to enable the settling of heavy solids to the bottom of the tanks and the lighter to float to the surface. There is a generally accepted international minimum standard of three hours retention time and a maximum overflow rate of 125 metres cubed / day / metre length of weir. The length of the weir is the width of the tank. At Tahuna, there are installed three tanks each 75 metres long by 16 metres wide. This then gives a combined weir length of 16×3 = 48 metres. The plant is currently handling some 55,000 cubic metres per day during dry weather, which, converts to 55,000 /48 = 1145.8 cubic metres each metre of weir length. Almost “ten times” the recognised standard. The system was further compromised by the recent gathering of the sewage from the Peninsula plus the shutting down of the Sawyers Bay Treatment Plant and the diversion of the West Harbour sewage to Tahuna. So it can be safely assumed that there is no way that sewage can be prevented from going to the ocean without a major rethink of the treatment plant.

    So, what to do? Well, we could start by looking at the sewage as perhaps a resource instead of a problem. What is the solid content of our sewage? Well, we know that it has, in a dried dewatered state, an average calorific (energy) value of 23865 kilojoules per kilogram.

    Further investigation would suggest that if we returned to the drawing board and approached the problem as a resource-based one, instead of a disposal one, then a happier outcome could be achieved. I say this, because international case studies and research indicates a lot of interesting prospects. In fact, it would seem not unreasonable to predict that, with an holistic approach we could arrive at a solution which would see the pipe outfall extension as unnecessary, also, there could be no need for anything but innocuous ash to go to landfill. Further, there could be a handsome positive surplus cashflow from the complex.

    How can this be achieved? Well, first the matter of separation of solids must be addressed. Next, the remaining liquid effluent must be rendered sterile. Now, it has been proposed to do this by ultraviolet sterilisation. Problem is that this method is only really effective in potable (clear) water. The reason is that it depends on the efficient transmission of light, and this would be seriously compromised in grey water, not to mention that the presence of even small solids would expose the fact that ultra violet rays have a very limited ability to penetrate. Also, the fact that the water would be dirty would pose serious fouling of the tube array and further erode the ability of the light to transmit.

    The solution would be to irradiate the effluent. This could be done by the use of caesium or cobalt 90 radio isotopes. Not an acceptable option with NZ’s policy relative to nuclear fissionable materials. However, the use of electron beam accelerator technology is a well proven process and with no afterlife residue it would be totally practical to render the effluent innocuous and thus able to be discharged to the ocean via the existing outfall. There is, however, another possible solution to the matter of this sterilisation which I detail further on. It is related to the steam boiler suggestion.

    What to do with the resulting sludge? Well, incinerating it is one simple solution which is already done in a very small way. If this was done employing a steam boiler then the resulting steam could run a steam turbine/generator which, on the amount of fuel apparently available, could produce a theoretical 15 megawatts of electricity. However, allowing a conservative efficiency factor of just some thirty per cent then it could be seen that between three and five megawatts of electricity could be produced. Enough to provide all of the plant’s requirements with a surplus to be sold to the national grid or as a contra against other council energy requirements.

    Now we come to the function of condensing the exhaust steam to water to be returned to the boiler. If this was done by the utilisation of a set of counter flow regenerative plate heat exchangers using the liquid solids free waste water then it would appear that this could condense the steam at the same time that it raises the waste water up to, and above, the necessary temperatures to achieve pasteurisation, hence sterilisation. Preliminary calculations would indicate that at a water flow rate of 2,300 cubic metres per hour sufficient energy in the exhaust steam could be available to do the job. It certainly seems well worth a professional independent examination. If it was proven to be a serious solution then this could obviate the need for the process of irradiation.

    It would seem that this could probably be achieved, well within the budgets of around $70 million presently proposed.

    If council wanted to minimise costs, it is, in view of the potential to generate energy, quite likely that joint venture capital monies could be available to mitigate the council’s amount of borrowing to solve the problem. Also, I suspect that this type of energy recovery and conversion project would meet some of the criteria required to attract valuable financial assistance from central government.

    It is for all the reasons outlined above, that I respectfully request your earnest consideration of the matter. It seems at the very least, that a step back and re-evaluation of the project should be undertaken. After all, it is in the interest of both the ratepayers and the environment that the best possible solution at the best possible cost is arrived at. I commend this report for your immediate attention.

    Calvin Oaten

  15. Phil

    The problem with Allanton, Triple X, is the lie of the land. The polluted liquid run off from the existing septic tanks heads straight to the Taieri River. Or collects in the small gullies along the way.

    You know, if they replaced every toilet pan in Allanton with a “source separation” toilet, there wouldn’t be so much of a problem. Liquid human waste is essentially sterile, and only becomes a problem when it gets contaminated by solid wastes. As happens in current reticulation systems. If you divert the liquid waste immediately, then there’s no problem in discharging it to the land or reusing it a greywater. That leaves only the dry solid waste sitting in the tanks to be removed.

    Simple, effective, and low maintenance system, I think that Eco-Toilets sell the pans.

  16. Allanton residents poo in their own nest and other ratepayers pay almost all the cost of cleaning it up?
    Whatever happened to the principle of polluter pays?
    This is going to be a very expensive precedent for the City.

    • Elizabeth

      As far as I’m aware there’s been extensive consultation with the Allanton community. As a Dunedin resident I’m perfectly happy to pay for infrastructure services that allow a community in the greater Dunedin area to have water and waste systems and upgrades as appropriate. Otherwise what’s the point. Do we not support our rural population?

  17. Phil

    Well, of course ratepayers from one area pay for work in another area. That’s how rates work. If the footpath outside your street needs repaired, do you really think they are using only the money they have collected from your rates? Would you accept that your footpath doesn’t get fixed if you personally haven’t paid enough rates that year to cover that work? Of course not.

  18. Phil

    A large part of the issue with septic tanks is that there are no definitive laws governing the quality and installation of septic tanks. Not in Dunedin. The ORC issues a Resource Consent, but only if the applicant’s property expects to discharge a certain amount of waste to land. There is a maximum permitted amount of discharge, but how that is achieved is left up to the applicant. It doesn’t form part of the DCC Building Consent inspection process. And the ORC doesn’t follow up once the consent has been issued. So there’s no-one to monitor the quality of the product or methods.

    Take a new house with 2 people living in it. No Resource Consent is required for the installation of a septic tank, because the discharge is deemed to be low. 5 years later, the couple sell their house, to a family of 6 people. A Resource Consent would have been required if this family installed the tank, but they didn’t. It’s already there, and the ORC doesn’t know that the occupancy level has changed.

    It’s a glaring hole that effects the whole country, not just Dunedin. The Hawkes Bay is facing huge ground pollution issues directly as a result of septic tanks. Last I heard they were trying to make ALL septic tanks subject to Resource Consent requirements, which would then require tanks to be of a sufficient size and quality. And there was a proposal to give all existing septic tank owners 10 years (I think) to bring their tanks up to current compliance levels.

  19. Richard

    Your comment is not really accurate. Council recently adopted a new policy on ‘New Connections’ across the city after public consultation. It is probably on the DCC website, but I do not have the time to check.

    As for Allanton, current property owners will be paying a fair chunk of the capital cost while any owners of properties on which new buildings are constructed will pay FULL costs.

  20. I understand that Allanton residents will pay 20% of the capital cost for their section. If new houses are built on currently empty sections then they will pay 100%, but this is unlikely to happen much. As two-thirds of the sections in Allanton are empty, the Council will pay 93% of the Capital cost.
    People who chose to live in the country are responsible for dealing with their own sewage. I understand the financial burden that this imposes on current residents, but a better way to deal with this would have been to give a loan until the property was sold.
    This schema has increased the value of Allanton properties because they are no longer at risk of enforcement action from the Regional Council, and any new homes will have to pay the full costs.
    The message that the Council is sending to other country areas is that if they create a pollution problem by not maintaining their sewage systems, or upgrading to newer technology, then the Council will bail them out.

  21. Phil

    It’s not a simple blame game. There are issues with tanks overflowing, and that’s the owners’ responsibility. There’s the second issue for the liquid run off from the tanks. Poor topography, high water table, saturated soils, and substandard systems are all contributing factors. But, as there were no consents sought or required, and no enforced compliance, it’s difficult to quote law breaches when it comes to enforcement action. as I mentioned earlier, Allanton’s case is not unique. Outram is facing a similar issue. The number of small septic tanks, non consented and perfectly legal, have resulted in the ORC declining consent for larger properties where resource consent has been necessary. Hawkes Bay is the poster child for the worst case scenario. Intensive farming coupled with a high number of septic tanks. I believe that all septic tanks should require resource consent, regardless of size. In the same way that water bores are required to. If nothing else, so that there is a record of where they are. That could be rectified with a by-law.

    • Elizabeth

      ### Odt Online Thu, 26 Nov 2009
      Allanton sewer system approved
      By Chris Morris
      Plans for a new pressure sewer system at Allanton, costing almost $1 million less than previously expected, have been welcomed by Dunedin city councillors.
      Read more

  22. Richard

    “The message that the Council is sending to other country areas is that if they create a pollution problem by not maintaining their sewage systems, or upgrading to newer technology, then the Council will bail them out”.

    Check the new policy, Alastair, and you will find that this is not the message at all. The criteria is very clear. What is to be done at Allanton does not set a precedent.

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