Tag Archives: Natural Hazards

Dunedin’s second generation district plan (2GP) —notes on Natural Hazards

Received from Neil Johnstone
Wed, 3 May 2017 at 7:19 p.m.

Message: Last Thursday (27 April) I presented the remainder of my submission on Natural Hazards. Notes attached in case they might help anybody’s further efforts.

{The notes from Mr Johnstone are public domain by virtue of the consultative 2GP hearing process. -Eds}

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2GP PRESENTATION NOTES: LANDSLIDES
Neil Johnstone

I have no property interest in any landslide hazard area (although I did previously), nor in the Water of Leith catchment, nor in South Dunedin. My main purpose in appearing at this stage is to bring to the panel’s attention that the expert (so-called) opinions received from Otago Regional Council’s (ORC) natural hazard analysts are often deficient to the detriment of the 2GP process and the city’s residents.

I am a long-term resident of Dunedin and am highly experienced in flood control issues and solutions. I am appearing here on my own behalf, therefore not strictly as an Expert Witness in this instance, although I have done so in past years both in both the High Court and the Environment Court. I also acted as lead technical advisor to the NZ Govt investigation into the massive 1999 Clutha flood. My detailed investigations have ranged from simple issues such as the Water of Leith (as Investigations Engineer at Otago Catchment Board and ORC) to the entire Clutha catchment (in varying roles). These investigations have often incorporated the construction and operation of accurate, properly verified models.

I am now semi-retired MIPENZ, but still running my own consultancy on a reduced basis. I am a highly experienced expert in flood issues, I am much less so wrt landslide identification and mitigation (but I know a nonsensical report when I read one). ORC hazard analysts responsible for the landslide buffer zones originally imposed across my former property (and many others) need to accept that their approach was seriously flawed, and far from expert. Paul Freeland has mentioned to me in a recent phone conversation that Dunedin City Council (DCC) should be able to have confidence that ORC hazard analysts are expert. I have no strong criticism of Mr Freeland, but those days have passed – in this region at least – when expertise was based on proven performance, and not on a position’s title. A property previously owned by my wife and me in Porterfield Street, Macandrew Bay was quite ridiculously misrepresented in ORC’s landslide report of September 2015. The landslide hazard zone on that property has apparently now been removed, but uncaring damage has been done to us, and no doubt to many others. The Hazard 2 zone was reportedly imposed without site inspection, or without anybody properly reviewing output or checking accuracy of references.

[Reason for submitting: Natural Hazards section of 2GP dominated (undermined) by ORC hazards staff input and DCC failure to verify/review; DCC presumption that ORC “experts” do/should have appropriate expertise. We appear to be witnessing a proliferation of Hazard Analysts in NZ Local Government with little relevant experience or skill.]

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2GP PRESENTATION NOTES: SOUTH DUNEDIN
Neil Johnstone

The comments re South Dunedin flood hazard contained in my original written submission were written prior to DCC’s producing its inaccurate flood reports in respect of the South Dunedin flooding of early June 2015 in which high groundwater levels were held to blame. These DCC reports were eventually released in late November 2015 and April 2016 respectively. My analyses (well after my original submission) demonstrated that the prime cause of widespread flooding in South Dunedin was DCC’s failure (in order of probable significance) to utilise the bypass facility at Tahuna Wastewater Treatment Plant, to fully utilise its stormwater pumping capacity at Portobello Road, and to maintain its stormwater infrastructure (mudtanks etc). Inflow of “foreign” water from the St Clair catchment added to the depth of inundation in some areas. All these can be remedied by a diligent Council. Some have already been remedied, as positively demonstrated in the admittedly rather over-hyped rain event of the subtropical cyclone remnant around this past Easter.

ORC natural hazard analysts were probably responsible for the origin of the groundwater myth as a cause of the South Dunedin flooding in their Coastal Otago Flood Event 3 June 2015 report. Reference was made there to “elevated” ground water levels. They followed up with a contentious report (The Natural Hazards of South Dunedin, July 2016). This opens by stating that the June 2015 flooding was caused by heavy rainfall and high groundwater levels, with no mention of mudtanks, or pumping failures (plural). Such reporting cannot be treated as balanced, nor its authors credible. Elsewhere, ORC essentially conceded the groundwater myth in Rebecca Macfie’s excellent NZ Listener article entitled Flood Fiasco (June 11, 2016).

Shortly after, however, ORC produced the aforementioned South Dunedin Hazards report (backed up by an embarrassingly inaccurate video presentation) that seems to reflect a desire to preach doom rather than convey a balanced defendable scientific analysis of South Dunedin realities and solutions where needed.

One of the worst features of the report and subsequent video was the depiction of projected permanently inundated areas of South Dunedin based on ORC modelling of rising sea level effects. These depictions made front page news in the Otago Daily Times with flow-on reporting nationally. The mapped areas of inundation are actually taken from an earlier ORC report entitled The South Dunedin Coastal Aquifer and Effect of Sea Level Fluctuations (October 2012). The modelling was based on limited information, and the findings would therefore be expected to be of limited reliability. The 2012 report essentially confirms this, noting that modelling of existing conditions overestimates actual groundwater levels (by the order of half a metre in places). Figure 2 (Scenario 0) of that report shows significant permanent ponding for current conditions. None exists in reality. Almost lost (in Section 3.8) are the following (abbreviated, and amongst other) concessions:

• Uncertainty of input data
• Potential inaccuracy of model predictions
• High level of uncertainty
• Groundwater system is poorly to moderately well characterised
• Aquifer properties are poorly understood or quantified
• Each of these uncertainties could have the effect of overestimating the groundwater ponding in the current setting.

The reader is advised to read the full Section 3.8 to ensure contextual accuracy. In my view (as an experienced modeller), a study that cannot even replicate known existing relationships is imperfectly calibrated and unverified. It cannot therefore be relied on. Strictly speaking, it does not qualify as a model. The relationship between possible sea level rise and consequent groundwater impact remains highly uncertain.

Unfortunately, the 2016 ORC South Dunedin Hazards report (and video) chose to reproduce the 2012 ponding predictions using more recent data (but without any better appreciation of aquifer characteristics), but the predictions are similar. It is noted that no Scenario 0 mapping is included in the latter report, nor are the model’s inherent weaknesses described. No admission of the potential modelling inaccuracies is presented other than the following note in Section 4.1: “Further discussion of the original model parameters, model calibration and potential pitfalls is included in the ORC (2012a) report, which can be accessed on the ORC website”. I believe that all parties were entitled to know unequivocally that the modelling was unreliable and unverified.

The 2016 report also makes reference to the fact that dry-weather ground water levels at the Culling Park recorder are at or below mean sea level. This is attributed by the authors to leakage of ground water into the stormwater and wastewater sewers. If that is correct (I would reserve judgement as to whether there may be other factors), then we are witnessing just one example of how an engineered solution could be utilised to dissipate increasing depth of groundwater. Such solutions are canvassed in the BECA report commissioned by DCC several years back.

To summarise, South Dunedin’s exposure to flood (current or future) is poorly described by ORC hazard analysts. The 2GP process seems to have seen these analysts “adopted” by DCC planners as their experts. I consider that to be an inappropriate approach to the detriment of our citizens.

The proposal to require relocatable housing in South Dunedin seems premature, and based on highly questionable information. The proposal for relocatable housing in South Dunedin also rather pre-empts the currently-planned DCC study of overseas approaches to sea level rise solutions.

Requiring relocatable houses will likely simply mean that aged houses that should in time be replaced will be repaired instead. Who is going to build a new relocatable house if they have nowhere to relocate to and probably insufficient money to acquire the requisite land? The proposal to require relocatable housing is ill-considered and premature in my opinion.

With respect to ground water issues across South Dunedin, the 2016 Hazard Report presents –

The reason for my pointing out these facts is to encourage Commissioners to take a step back from the current hysteria surrounding South Dunedin. Had the 2015 flooding extent been restricted (as it should have been) to that which occurred in a slightly larger rainfall event in March 1968, the event would have already been forgotten. Seemingly, at least partly as a result of that hysteria, the proposal to require relocatable housing in South Dunedin seems premature, and based on highly questionable information. Just as ORC floodplain mapping contradicts its in-place flood protection philosophy, so does the proposal for relocatable housing in South Dunedin also rather pre-empt the currently planned DCC study of overseas approaches to sea level rise.

Requiring relocatable houses will simply mean that aged houses that should in time be replaced will be repaired instead. Who is going to build a new relocatable house if they have nowhere to relocate to and probably no money to acquire the requisite land? The proposal for relocatable housing is ill-considered and premature in my opinion.

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2GP PRESENTATION: URBAN STREAM HAZARDS
Neil Johnstone

Urban Stream Comment re Leith and Lindsay Streams:

ORC’s mapping is said to be of residual flooding (post-flood protection works of the past 80-plus years), but actually represents what might have been envisaged many decades back in something considerably greater than the record 1929 flood with none of the very significant channel works of the 1930s, 1940s and 1960s; or even those lesser improvement of the 2010s in place. The ORC 2GP mapping includes areas that didn’t get flooded in 1923 or 1929. I agree with some potential dangers of stream blockage (especially in Lindsay Creek, and to a lesser extent at Clyde Street and Rockside Road), but one can only consider locations of feasible blockage in today’s conditions. Furthermore, accepted professional practice for flood plain mapping requires detailed hydrology, probability analyses, climate change allowance, hydrograph routing, in-channel modelling (allowing for stream capacity variability), and overland flow modelling. ORC’s flood mapping incorporates none of these fundamentals; instead, it reads as little more than a colouring-in exercise, when a professionally researched technical document is required. In short, ORC’s hazard analysts have carried out no fit-for-purpose analysis for a District Plan process.

Interestingly, the concerns expressed by ORC hazard analysts re channel blockage are entirely inconsistent with ORC’s own design philosophy and consent application evidence for the recent Flood protection scheme (so called). Design Philosophy minimises the issue.

Very briefly, the mapping is challenged for the following reasons (inter alia):

No descriptions of the effective flood protection initiatives (OHB -1920s and 1930s, DCC -1940s, OCB -1960s) are included. These works have ensured that overtopping is practically impossible in the George Street to Cumberland Street reach, the Clock Tower reach and Forth Street to Harbour reaches. Flood protection in these areas are all built to a much higher hydraulic standard than the so-called ORC scheme of the past decade, and to a far, far higher standard than existed pre-1929.

It is further noted that ORC’s own Design Philosophy Report (OPUS for ORC, 2005) for the proposed Leith/Lindsay flood protection scheme is adamant that debris traps recently (then) constructed at Malvern Street and Bethunes Gully would further mitigate any debris problems. Refer paras 7.7 and 10.6 of that document.

Ponding is mapped where water couldn’t even reach in 1929 (peak flood currently estimated at 220 cumecs, and predating flood protection measures) in the wider CBD area. Flows along George Street in the 1920s only occurred south as far as about Howe Street, then re-entered the river. Nowadays, the accelerating weir above George Street and the structural high velocity channel immediately downstream provide much more clearance than existed in 1929. [Most outflow then from the river occurred much further downstream.] In those downstream reaches, many of the bridges have been replaced or upgraded. Possible remaining points of interest are the hydraulically insignificant extension (circa 2015) of the St David Street footbridge, the historic Union Street arch footbridge, and the widened (circa 2012) Clyde Street road bridge. The flimsy St David Street bridge would not survive any hydraulic heading up so there would likely be of little flood consequence, and backing up upstream of Union St would be largely inconsequential because of the height of the Clock Tower reach banks immediately upstream. The Clyde Street bridge is acknowledged as being lower than optimum, but it has not created any issues in its half century existence. Any overtopping there could only impact on a limited area between the bridge and the railway line.

Overland lows beyond (east of) the rail line remain highly improbable because of the ongoing blocking effect of road and rail embankments. Flows as far as the railway station to the west of the rail line are also highly improbable nowadays as only the Clyde Street area could conceivably contribute.

The 1923 photograph showing ponding along Harrow Street is presented by ORC with an unfortunate caption stating that the water is sourced from the Leith. Some undoubtedly was, but the whole of the city was subject to “internal” stormwater flooding from Caversham tunnel, across South Dunedin to the CBD and beyond. To illustrate further, a NIWA April 1923 flood summary (accessible online) provides a summary of some of the information more fully described in technical reports and newspaper accounts, including:

• Portions of Caversham, South Dunedin, St Kilda, the lower portions of central and northern areas of the City and North East Valley were completely inundated.
• Water in South Dunedin was waist deep.
• The Water of Leith rose considerably and burst its banks in many places, causing extensive damage along its banks and flooding low-lying areas.

Today’s stormwater infrastructure is rather more extensive and effective (when maintained), and DCC has a continuing legal obligation to provide to maintain that service.

The levels plotted across Lindsay Creek seem highly pessimistic. Levels are shown to be of the order of 2 metres above North Road in some locations at least. I have [no] knowledge of any such levels ever having been approached. Care must be taken not to include unfloodable areas in the mapping. I don’t however discount localised channel blockage, and the channel capacity is substandard in many areas. The valley slope ensures that overland flow will achieve damaging velocities. Such velocities are noted in the NIWA summary.

Of greater concern to me, however, is that ORC’s mapping appears to have seriously underestimated the significance of potential Woodhaugh flood issues:-

The river channel through here is both steep and confined. The influences of Pine Hill Creek (immediately upstream) and Ross Creek (immediately downstream) add to turbulence and bank attack. The area was ravaged in 1923 and 1929, and there have been evacuations in some much lesser events in later decades. These areas are at considerable risk in a 50- to 100-year plus event. Hardin Street, Malvern Street had houses evacuated in the 1960s flood. High velocity, rock laden flows and mudslides can all be anticipated, and difficult to counter. Area below camping ground / Woodhaugh was overwhelmed in floods of the 1920s – a focus for flooding depth and velocity.

If the 2GP process is to include urban flood maps, these should be diligently derived, based on historical record and appropriate modelling. The mapping should reflect the real flood risks (including likelihood, velocity and depth). The decreasing flood risk from Woodhaugh (potentially high impact) through North East Valley (moderate impact) through to the main urban area south of the Leith waterway (localised and of little-to-zero impact) should be reflected in the mapping.

[ends]

2GP Hearing Topic: Natural Hazards
https://2gp.dunedin.govt.nz/2gp/hearings-schedule/natural-hazards.html

█ For more, enter the terms *johnstone*, *flood* and *south dunedin* in the search box at right.

Related Posts and Comments
6.6.16 Listener June 11-17 2016 : Revisiting distress and mismanagement #SouthDunedinFlood
10.6.16 “Civic administration” reacts to hard hitting Listener article

[DCC Map differs from what was notified]

Posted by Elizabeth Kerr

This post is offered in the public interest.

8 Comments

Filed under DCC, Democracy, District Plan, Dunedin, Education, Geography, Health & Safety, Housing, Infrastructure, Name, New Zealand, OAG, Ombudsman, People, Politics, Project management, Property, Proposed 2GP, Public interest, Resource management, South Dunedin, Town planning, Urban design

Cracking the truth : June 2015 South Dunedin flood

OPINION received from Neil Johnstone
Sat, 10 Sep 2016 at 12:42 a.m.

Richard Stedman produces (below) a succinct review of the causes of, and failures after, the South Dunedin flood of June 2015. His frustrations appear to match those of Hilary Calvert that were published a few hours earlier. My reviews previously published on What if? Dunedin commencing back around February give more detail.

For your readers’ further consideration, Richard has highlighted the ‘200mm increase’ in flood level as a result of Portobello Road pumping station failures. The figure was derived by me, and appears in my review of the first DCC flood report. To my knowledge the only clear comparable DCC concessions have come from chief executive Sue Bidrose who admitted the figure publicly at the 20 June 2016 (yes, 2016) South Dunedin Action Group-organised public meeting, and subsequently.

The first DCC flood report (30 Nov 2015) is adamant that high groundwater was the cause of the flooding, and enough Councillors bought right into that excuse at the following Infrastructure Services Committee meeting. Just go back and view the video, if you’ve forgotten.

Dunedin City Council Published on Dec 7, 2015
Dunedin City Council – Council Meeting – November 30 2015
Discussion of the report starts at 1:09:52

The second (mudtank) DCC report of 26 April this year states: “Although Portobello Road’s performance did explain some of the length of time flooding was evident, much of the flooded area was below road level…” (para 31). No mention of increased depth of flooding there either, you will note.
[View report at Infrastructure Services Committee: Agenda & Reports 26 April (Part A, Item 5) pp 6-27.]

Neither DCC report mentions the additional depth of flooding caused by inaction at the Musselburgh pumping station.

History and ongoing design may rely on written commentaries. For the wellbeing of South Dunedin people, we must therefore continue to counter the misinformation contained in DCC reports, and in the more recent ORC (DCC-backed) South Dunedin “hazards” report. Even if ODT has switched off.

Related Posts at What if? Dunedin
8.3.16 [Review 1] Johnstone independent review of DCC report
19.5.16 [Review 2] Johnstone review of 2nd DCC report

Correspondence supplied
7.3.16 Letter, Chief Executive Sue Bidrose to Neil Johnstone
10.3.16 Response from Neil Johnstone to CE Bidrose

sue-bidrose-south-dunedin-a-changing-environment-radionz-co-nz-detailSue Bidrose at ORC/DCC hazards presentation [radionz.co.nz]

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OPINION received from Richard Stedman
Fri, 9 Sept 2016 at 8:24 p.m.

The ODT editorial department is peopled by closed minds, a number of whom subscribe to the climate change/rising sea level mantra and therefore manipulate their content to support their distorted view of the world. Mr Morris is captured by the former/present regime at city hall, a fate which befalls every reporter assigned to that round once they get their feet under the table.

Two weeks ago I prepared an opinion piece re the election and South Dunedin, outlining some of the issues as I see them in the hope that it might be published. I thought it was honestly held opinion, but it was rejected because it added “nothing new” to the debate, yet they run to Cull at every turn and run column after column of repetitive nonsense.

The following is my submission submitted on 24/8 and rejected the same day in this message: “Thanks for this submission, but we have had a “deluge” of flood letters and op eds from all sides so I don’t feel the need to highlight the issue again at the moment – certainly if there’s not anything new in it, as such”.

I have seen little evidence of the cited “deluge”.

The South Dunedin flood of June 2015 may be a tipping point during next month’s local body election. Many voters will look at the burgeoning candidates list for the Dunedin City Council and ask “who will provide the cornerstone elements of responsibility, accountability and integrity?”

Residents and business owners in South Dunedin have been sorely tested in recent times through the failure of the DCC to maintain its infrastructure. Among those adversely affected were elderly residents at Radius Fulton Home, including a number of dementia patients, the most vulnerable in our community, who were subjected to floodwaters containing sewage and transferred from the safety of their home in a crisis beyond acceptance. Some were accommodated as far away as Balclutha and Oamaru and three months passed before the facility was re-opened.

Following the flood, obfuscation clouded the failures that led to the inundation of homes and businesses and the investigation and report into the affair was 12 months in gestation. Officials and councillors, captured by the twin mantras of climate change and rising sea level, avoided any suggestion of culpability to limit the likelihood of litigation, and offered no solace that might have been construed as admission of liability.

The mayor and others were quick to blame rising sea level causing increased groundwater, combined with an “extreme weather event”, the result of climate change, and went so far as suggesting that a planned retreat from South Dunedin may be necessary in the future. The rainfall was described as a one-in-100-year event then gradually downgraded, but none of these pretexts are realistic. Questions arise over who is responsible for what, and how serious are the threats of rising sea level, more frequent adverse weather caused by climate change, and the “sinking of South Dunedin”, not to mention “retreat”.

Dunedin and environs have been subjected to much larger weather events in the past. Flooding of the entire city is well recorded and in particular photographs of the 1923 flood depict rowing in floodwaters in the city as well as inundation in South Dunedin. During a storm in 1898 large tracts of St Clair Esplanade were destroyed by the sea which damaged many houses, leaving some partly suspended. More recently, the storms of 1968 were greater than last year’s, delivering 10% more rainfall. In 1968 there were 90 properties invaded by floodwater, whereas last year some 1200 properties were flooded and many contaminated with effluent. Clearly last year’s event was exceptional only for the damage created and lives disrupted.

At a public meeting in South Dunedin on June 20, more than 12 months after the event, those affected had an opportunity to hear an explanation in the hope that someone might take responsibility for the extent of the damage. Despite a good representation of councillors there was no empathy and no likelihood of accountability. What the meeting heard was a long explanation of how the three-waters system works, or doesn’t work, as the case may be, and of failure at the pumping station from chief executive, Dr Sue Bidrose and other staff. The question is “when did the city’s councillors abdicate?”

south-dunedin-flood-june-2015-radionz-co-nzSouth Dunedin June 2015 [radionz.co.nz]

It can be argued that the damage and distress was the result of neglect, but the DCC says problems at the pumping station added only 200mm to the flooding which would have occurred anyway. Which 200mm was it? Maybe the first 200mm flowed across the ground, reached blocked drains then deepened throughout the area, or perhaps the last 200mm increased the depth and entered homes and business premises carrying undesirable flotsam. Without the extra 200mm would the water have stopped at the thresholds rather than flowing inside?

What of the rising sea level threat? Is it as urgent and as devastating as the commissioner for the environment, some DCC councillors and the Green Party say? The Greens proffer that the Government should help to pay for the reconfiguration of South Dunedin. Why? There has been no disaster on the scale of the Canterbury earthquakes and there is no immediate danger condemning South Dunedin, for if sea level were to rise according to some projections, north Dunedin and other areas are also in jeopardy meaning protection on the coast is futile because the flat land would be inundated from the harbour.

Could it be that models of sea level rise around New Zealand are exaggerated and distorted by the multiplier effect have been grossly over stated? And do the $7 million apartment complex at the Esplanade to be completed next year and the DCC’s belated discussion on a South Dunedin hub indicate mixed messages on the subject?

There is no doubt that the infrastructure must be maintained to the highest level and upgrading implemented with haste. The seafront calls for a level-headed approach to protect the sandhills which shelter the city from the ocean. In the past a network of groynes captured the sand, maintaining a broad beach to dissipate the energy of the waves. The network succeeded for nearly 100 years, but without maintenance fell victim to the ocean, so is it time to reinstate a similar system and then plan carefully for the next 100 to 200 years?

Council says that infrastructure will require “tens of millions of dollars” we cannot afford, but plans to spend some $37 million on George Street and the Octagon, followed by development of the harbourside. These “tens of millions” surely must be re-allocated to South Dunedin for infrastructure, to build a second pumping station, and provide realistic coastal protection.

Dunedin needs new councillors who will make hard decisions, reduce spending on fripperies and attend to basics; people who are prepared to drill deep into reports and costings and who are not afraid to make unpalatable decisions when needed rather than govern with slogans and platitudes.

Declaration: Conrad Stedman is my nephew.

Posted by Elizabeth Kerr

Election Year. This post is offered in the public interest.

4 Comments

Filed under Business, Climate change, DCC, Democracy, Dunedin, Economics, Education, Events, Finance, Geography, Health, Heritage, Housing, Infrastructure, Media, Name, New Zealand, OAG, Ombudsman, People, Politics, Project management, Property, Proposed 2GP, Public interest, Resource management, Site, South Dunedin, Tourism, Town planning, Transportation, Travesty, Urban design, What stadium

Johnstone on ORC report : ‘The Natural Hazards of South Dunedin’ (July 2016)

The Natural Hazards of South Dunedin – July 2016 [read online]
Otago Regional Council
ISBN: 978-0-908324-35-4
Report writers:
Michael Goldsmith, ORC Natural Hazards Manager
Sharon Hornblow, ORC Natural Hazards Analyst
Reviewed by: Gavin Palmer, ORC Director Engineering, Hazards and Science
External review by: David Barrell, Simon Cox, GNS Science, Dunedin

Received from Neil Johnstone
Sun, 29 Aug 2016 at 8:17 p.m.

Message: Misinformation on the causes of the June 2015 South Dunedin flood have abounded since the event. As if the victimised residents haven’t suffered enough from others’ inactions (before and during the event), they are now being subjected to a hazards discovery process whose vigour appears to be exceeded only by its own recklessness. Following are a commentary of the hazards approach adopted by the Otago Regional Council (ORC), and a summary of my investigations into the flood event that I commenced after the publication of Dunedin City Council’s first flood report back in November 2015.

You can download Neil Johnstone’s report or read it below (formatted slightly differently to suit the WordPress template).

█ Download: A REVIEW OF ORC REPORT THE NATURAL HAZARDS OF SOUTH DUNEDIN (1) (PDF, 587 KB)

AN APPRAISAL OF RECENT REPORTING OF SOUTH DUNEDIN HAZARDS

N.P JOHNSTONE, BEng (Civil), MIPENZ

1. Introduction

There is some irony that DCC and ORC should be planning “drop in” sessions for residents in respect of South Dunedin hazard issues during September 2016, some 15 months after the major flood. The prime cause of flooding in June 2015 was DCC’s failure to maintain its infrastructure (not just mudtanks), and its failure to operate its pump stations to their intended capacities. The subsequent spread of misconceptions (i.e. groundwater levels, rainfall significance etc) surrounding the flood causes was at least partly due to inaccurate ORC analyses and reporting.

Repetitive and new doubtful information emanating from ORC via its latest report has been noted. Presentations and an over-simplistic video production have been observed. A footnote covering these observations is included at the end of this appraisal.

Long-delayed DCC reports on causes of the South Dunedin flooding have already been strongly criticised by the author. Specifically discredited are misrepresentations of sea level, groundwater and rainfall ranking. Accepted now by DCC as factors (somewhat grudgingly, and depending on the audience) are mudtank blockage and Portobello Road pump station failures (plural); still to be fully acknowledged are the failures at Musselburgh Pumping Station.

Attention is now turned to significant parts of hazard reports produced by the Otago Regional Council and utilised by DCC.

2. Coastal Otago Flood Event 3 June 2015 (ORC, published October 2015)

This report deals with a wider area than South Dunedin. It is apparent that ORC staff never visited the flooding areas of South Dunedin on 3 June, but took advantage of fine weather to take some water level readings the following day. The opportunity for useful progressive surface water level recording was thus lost. Levels were collected at some 150 points on 4 June. ORC’s main conclusion was that “localised variations in topography were probably the main driver of flood depth”. Or, put another way, water depth was deepest where the ground was lowest. This seems hardly surprising, and even trivial. No attempt was made to explain the photographic images presented of extensive ponding remaining well after the rains had ceased. The phenomena of blocked mudtanks and unutilised pumping capacity went seemingly unnoticed.

The report does usefully reference ORC’s four borehole recorders of groundwater, but makes the somewhat misleading assessment that groundwater levels were “elevated” prior to the rainstorm. This misinformation was seized upon by agencies such as DCC and the Office of the Parliamentary Commissioner for the Environment to highlight climate change impacts.

Having obtained the actual groundwater level data from ORC via the LGOIMA process, the author was able to reveal this “groundwater fallacy” in reviews from February 2016, but it was not until the publication of NZ Listener’s article (June 11-17, 2016) entitled ‘FLOOD FIASCO’ that ORC admitted that pre-flood groundwater levels were in fact “just a little bit above average”. ORC now seems intent on resurrecting this fallacy.

The ORC report fails to address the real and key issues of pumping station failures (Portobello Road and Musselburgh), or comparisons with much lesser flood impacts in the larger rainfall event of March 8/9 1968.

The report states that the 2015 24-hour rainfall was the largest since 1923. This was patently incorrect, but again was utilised by DCC to divert blame from their role in the disaster.

3. The Natural Hazards of South Dunedin (ORC, published July 2016)

The report states unambiguously in its Opening Summary that the major flooding of June 2015 was “a result of heavy rainfall, surface runoff, and a corresponding rise in groundwater”. By now, most people are aware that the causes of the flooding’s disastrous impact were failure to optimally operate pumping stations, failure to clear mudtanks, and failure to deploy staff to key areas during the event. Again, none of these factors is addressed in ORC’s report.

The report presents a table on its second page entitled “Factors Which Can Influence Flood Hazard”. Examples of exaggerated negativity include:

1. Heavy Rainfall:
– Many recorded instances of rainfall leading to surface flooding.
– Heavy rainfall events have occurred frequently over the last decade.

Comment: These conclusions do not appear to be supported by the report’s text, and are vague, factually challengeable and alarmist. Prior to 2015, no major flooding had occurred in South Dunedin since 1968, and even that was minor by comparison.

2. Sea Level:
– Groundwater level fluctuates (by up to 0.5m near the coast) on a twice-daily cycle in response to normal ocean tides.

Comment: All of South Dunedin is near the coast; most of the area does not experience such large fluctuations. This should have been made clear by the inclusion of groundwater data from all 4 ORC sites across the plain, not just from Kennedy Street.

3. Seismic:
– Large earthquakes could result in increased flood hazard on the South Dunedin plain, due to liquefaction-related land subsidence or direct, sudden, changes in land elevation relative to sea level.

Comment: All areas of NZ have some susceptibility to earthquake damage. Dunedin is amongst the areas at lowest risk; no incidences of even minor liquefaction have ever been reported in South Dunedin, and little or no clearly liquefiable materials have been identified (Refer GNS, 2014*). Continue reading

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Labour messing with South Dunedin, like Cull, unbidden

Not Listening [octavehighereast.com]Not Listening [octavehighereast.com]

There is little or no RISING GROUNDWATER at South Dunedin – this is an attack on the local community by Anthropogenic Global Warming (manmade climate change) believers like Curran, Clark, and Cull.

So-called ‘authorities’ are running their Politics over the top of the local Community, Failing to canvass the views of the local residents, property owners, service providers and businesses through agreed consultation methods Before pronouncing upon the area. This is disrespectful, dangerous behaviour. Unwarranted.

A lot of us will remember Labour MP David Clark’s importune speech on climate change at the public meeting held at South Dunedin on 20 June. He completely didn’t register the mood and understandings of the local audience.

Greenie Cull and the Labour Party are deliberately or inadvertently using South Dunedin as a Political Football. There are few votes to be earned from bullying and interference, thank god.

Listening —what is that.

Speaking after the tour, Mr Little said the area was a “prime candidate” for urban renewal under the party’s proposed Affordable Housing Authority.

### ODT Online Tue, 26 Jul 2016
Labour timeline for South renewal
By Timothy Brown
South Dunedin’s renewal will be showing “good progress” within six years of electing a Labour government, party leader Andrew Little says. Mr Little toured South Dunedin with Dunedin Mayor Dave Cull, Dunedin South MP Clare Curran, Dunedin North MP Dr David Clark and list MP David Parker after the area was earmarked by the Opposition as one urgently needing urban renewal. The group walked from Bathgate Park School, in Macandrew Rd, down Loyalty St into Nicholson St and on to Nelson St before returning to the school. They were accompanied by members of various social groups from South Dunedin.
Read more

****

### Dunedintv.co.nz Mon, 25 July 2016
Labour leader tours South Dunedin
Labour Leader Andrew Little has visited South Dunedin today, alongside a contingent of MPs and social service agency stakeholders. The group wandered around the areas hardest hit by last year’s floods, looking at the handful of houses still empty more than a year on. And Little took the opportunity to offer up his party’s plan to fix some of the issues.
Ch39 Link

Channel 39 Published on Jul 24, 2016
Labour leader tours South Dunedin

DUNEDIN – JUNKET CITY FOR LGNZ
“How do we Efficiently capture NZ Ratepayers’ Money for our Comfy Salaries”

### Dunedintv.co.nz Mon, 25 July 2016
Local government conference kicks off
The country’s annual Local Government conference is back in Dunedin for the first time in almost a decade. More than 560 delegates have piled into the Town Hall to discuss how to make New Zealand a better place to live and work. But it’s also serving as a way to address the tension between local and central governments.
Ch39 Video

LAWRENCE YULE GO HOME

█ For more, enter the terms *flood*, *sea level rise*, *stormwater*, *hazard*, *johnstone*, *hendry*, *south dunedin action group*, *debriefing notes*, *listener* or *lgnz* in the search box at right.

Posted by Elizabeth Kerr

Election Year. This post is offered in the public interest.

Listening ear-hand [mrhudyma.com]Larry King - Listen [via linkedin.com]

*Images: mrhudyma.com – Listening | linkedin.com – Larry King, Listen

94 Comments

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Johnstone disputes Opus review #SouthDunedinFlood

### ODT Online Thu, 7 Jul 2016
Flood review clears DCC staff findings
Dunedin City Council staff have been vindicated by peer reviews which backed their findings over the cause of last June’s devastating floods. The reviews, carried out by infrastructure consultancy firm Opus, backed the council’s findings South Dunedin and other parts of the city would have been flooded even if the city’s stormwater system was running at full capacity.
Read more

Opus peer reviews of DCC flood reports received (same day) following a LGOIMA request made on 7 July 2016:

DCC Nov2015 rpt review-final (PDF, 395 KB)

DCC Apr2016 rpt review-final (PDF, 329 KB)

****

A truly independent inquiry into the council’s performance around last year’s South Dunedin floods remains long overdue, writes Dunedin engineer Neil Johnstone.

### ODT Online Thu, 14 Jul 2016
Opinion: Report skims surface of South Dunedin flood saga
By Neil Johnstone
OPINION Readers of the Dunedin City Council-funded independent peer review of its post-flood reporting (ODT, 7.7.16) should be wary. The council’s delight with the review may prove short-lived. In brief, the Opus review:

● Recognises the 1968 rainfall event was bigger than that of June 2015 (contrary to repeated council claims).
● Fails to explore the reasons why the 2015 flood was a disaster, and the 1968 event was not.
● Makes assumptions about groundwater levels without referencing the actual data.
● Appears to consider the council’s assumption of zero ground infiltration has merit (note: the data disproves this).
● Believes mud-tank blockage impacts of the flood were “localised” (too bad if you were a local), but fails to consider the likely widespread impacts on South Dunedin of blocked mud-tanks in the St Clair catchment.
● States council reviews “suggest” its failures at the Portobello Rd pumping station caused an increase in flood levels of about 200mm.
● In fact, the first council review leaves the reader with no more than an opportunity to infer this, while the second council review only states that the failures may have influenced “the length of time flooding was evident”.
● I do not recall the council actually publicly admitting the 200mm figure before the South Dunedin Action Group meeting of June 21.
● Fails to address the flood impacts of the council’s total failure to operate its Musselburgh pumps for stormwater relief.
● Makes general statements to the effect that “primary” flooding would have occurred under any circumstance. South Dunedin residents know that “overwhelming” of stormwater infrastructure was not the concern; the avoidable flooding of our people’s houses and businesses was.

For all of the above reasons, and more, the Opus finding the council report’s conclusions were “robust” is concerning. A truly independent inquiry into the council’s performance pre, during and post-flood, at staff and political levels, is long overdue. ODT Link

Related Posts and Comments:
● 7.7.16 Where is the unreserved DCC apology to … South Dunedin ?
● 4.7.16 Presentations available —a) 4 July USA —b) 20 June SDAG
● 28.6.16 The Star and RNZ on raised flood levels #SouthDunedin
● 27.6.16 CULL commingled #AGWbullsfeatherartists
● 21.6.16 Mayoral Statement to South Dunedin
● 20.6.16 Public Meeting: South Dunedin Action Group #tonight
18.6.16 South Dunedin stormwater pipes —getting past the desktop ICMP
● 17.6.16 So we’re going to play it this way #SouthDunedinFlood
● 16.6.16 Public Meeting: South Dunedin Action Group #AllWelcome
● 6.6.16 Listener June 11-17 2016 : Revisiting distress and mismanagement
6.5.16 South Dunedin Action Group: Notes of meeting with DCC (3 May 2016)
14.4.16 South Dunedin flood risk boosters #ClimateChangeCrap #PissOffPCE
26.2.16 Mudtanks and drains + Notice of Public Meeting #SouthDunedinFlood
● 31.12.15 2016, have mercy !@$#%^&*
10.4.15 DCC: Natural Hazards

*Bullet points indicate comments entered after the public meeting 20 June.

█ For more, enter the terms *flood*, *sea level rise*, *stormwater*, *hazard*, *johnstone*, *opus*, *hendry*, *south dunedin action group*, *debriefing notes* or *listener* in the search box at right.

Posted by Elizabeth Kerr

Election Year. This post is offered in the public interest.

4 Comments

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The Star and RNZ on raised flood levels #SouthDunedin

The Star 23.6.16 (page 9)

[click to enlarge]
The Star 23.6.16 Tense moments at South D meeting p9 [water insert]

### radionz.co.nz 8:45 am on 21 June 2016
RNZ News
Dunedin council concedes flood worsened by faulty pumping station
By Ian Telfer in South Dunedin
Dunedin City Council has admitted a faulty pumping station made last year’s South Dunedin flood 20cm deeper than it would have otherwise been. The Council made the admission at a rowdy public meeting at the Nations Church last night about the flooding a year ago which damaged 1200 homes and businesses. Chief executive Sue Bidrose […] made a major concession, saying the council now accepted a key pumping station was blocked, adding an extra 20cm of water to the area. […] Shortly after the flooding, Mr Cull linked the event to climate change and warned South Dunedin may have to beat a managed retreat. Local woman Kathinka Nordal Stene said she was shocked Mr Cull undermined the community at the time when it most needed his support. She said the future of South Dunedin had become a major election issue, on which Mr Cull would be judged. Mr Cull was not at the meeting because he was visiting China. […] Leaders of the newly formed South Dunedin Action Group accused the council and its leaders of having a secret plan to abandon the suburb and blame it on climate change.
RNZ Link

23.6.16 Ch39: Candidates using flooding for political gain (+ Video)
21.6.15 ODT: Anger about South Dunedin’s future

Related Posts and Comments:
● 23.6.16 Sa pièce de résistance @ #DUD
● 21.6.16 Mayoral Statement to South Dunedin
● 20.6.16 Public Meeting: South Dunedin Action Group #tonight
18.6.16 South Dunedin stormwater pipes —getting past the desktop ICMP
● 17.6.16 So we’re going to play it this way #SouthDunedinFlood
● 16.6.16 Public Meeting: South Dunedin Action Group #AllWelcome
● 6.6.16 Listener June 11-17 2016 : Revisiting distress and mismanagement
6.5.16 South Dunedin Action Group: Notes of meeting with DCC (3 May 2016)
14.4.16 South Dunedin flood risk boosters #ClimateChangeCrap #PissOffPCE
26.2.16 Mudtanks and drains + Notice of Public Meeting #SouthDunedinFlood
● 31.12.15 2016, have mercy !@$#%^&*
10.4.15 DCC: Natural Hazards

*Bullet points indicate comments entered after the public meeting 20 June.

█ For more, enter the terms *flood*, *sea level rise*, *stormwater*, *hazard*, *johnstone*, *hendry*, *south dunedin action group*, *debriefing notes* or *listener* in the search box at right.

Posted by Elizabeth Kerr

Election Year. This post is offered in the public interest.

9 Comments

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Sa pièce de résistance @ #DUD

Monday, 20 June 2016
South Dunedin’s Future : It’s in your hands
Public meeting called by South Dunedin Action Group

au Sud Dunedin

Mock turtles on a Monday, and [a moment of meeting remembrance]
mon Dieu! Voix, la sienne! (my God! Voices, hers!) pronouncing la séparation des “poos” et “wees” —wastewater (grey water) from drinking water and stormwater as la raison d’être pour la stratégie de “Three Waters”……..
méfiez-vous ce qui sort du robinet (beware what comes out of the tap!) ou, était que la bouche (or, was that the mouth)

Flood, The People —inondation, inonderait le peuple
but, DON’T use politics against those “responsable” fr.

Channel 39 Published on Jun 22, 2016

### dunedintv.co.nz Thu, 23 June 2016
Candidates using flooding for political gain
A heated public meeting earlier this week brought last year’s South Dunedin floods back to the fore. The discussion around what to do for those still affected is one that members of the Dunedin City Council’s executive say they’re taking seriously. But there’s concern some involved parties are using the situation for political gain.

Malhereusement! Ceci est du jeu de puissance ineptes, d’elle-même
(Sadly! This is inane power play, of itself)

POST FLOODS

WHY WOULDN’T CANDIDATES CAMPAIGN FOR A BETTER COUNCIL TO SERVE AND REPRESENT THE PEOPLE OF SOUTH DUNEDIN AND ALL CITY RESIDENTS AND RATEPAYERS

CANDIDATES THAT IF ELECTED CAN KNUCKLE CIVIC CENTRE OPERATIONALS TO RESTORE POSITIVE TEAMWORK AND ENGINEERING EXPERTISE

Huh ?

This is THE time for Dunedin Politics and Examination of Dunedin City Council down to the last foul or stormwater, sewer.

Hourra !

Related Posts and Comments:
● 21.6.16 Mayoral Statement to South Dunedin
● 20.6.16 Public Meeting: South Dunedin Action Group #tonight
18.6.16 South Dunedin stormwater pipes —getting past the desktop ICMP
● 17.6.16 So we’re going to play it this way #SouthDunedinFlood
● 16.6.16 Public Meeting: South Dunedin Action Group #AllWelcome
● 6.6.16 Listener June 11-17 2016 : Revisiting distress and mismanagement
6.5.16 South Dunedin Action Group: Notes of meeting with DCC (3 May 2016)
14.4.16 South Dunedin flood risk boosters #ClimateChangeCrap #PissOffPCE
26.2.16 Mudtanks and drains + Notice of Public Meeting #SouthDunedinFlood
● 31.12.15 2016, have mercy !@$#%^&*
10.4.15 DCC: Natural Hazards

*Bullet points indicate comments entered after the public meeting 20 June.

█ For more, enter the terms *flood*, *sea level rise*, *stormwater*, *hazard*, *johnstone*, *hendry*, *south dunedin action group*, *debriefing notes* or *listener* in the search box at right.

Posted by Elizabeth Kerr

Election Year. This post is offered in the public interest.

Posted by Elizabeth Kerr

10 Comments

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