HAWKE’S BAY REGIONAL COUNCIL
Asset
Management and Biosecurity Committee
Wednesday 15 February 2012
SUBJECT: Haumoana Erosion issues
Reason for Report
1. In July 2011 Council
were updated on the content of a report prepared for HBRC and Hastings District
Council (HDC) on the potential for coastal erosion mitigation works proposed by
the community group Walk on Water (WoW) to gain resource consent. Mr Serjeant
reported that in his view the works were consentable, however he identified
that if the project was to be proceeded with, there are a number of crucial
investigations which are needed to confirm the design and to gain a better
understanding of the down-drift effects of the proposal.
2. That additional
work, jointly funded by HBRC and HDC has now been completed, and the cost
implications associated with the findings of that additional work have been
estimated.
3. John O’Shaughnessy
and Rowan Little of HDC will attend the meeting to update Councillors on the
results of their consultation to date, the outcome of the further
investigations recommended by Mr Serjeant, how that impacts on the estimated
cost of the project, and their proposed consultation approach and timeline.
Background
4. Investigations and
consultation into the matters of coastal hazards at Haumoana stretch back to at
least 2004 with the 2004 Regional Coastal Hazard Assessment undertaken by
Tonkin & Taylor Ltd (T&T). The 2004 assessment went on to form the
basis upon which the Councils would develop their policies for the future management
of the coastal environment including options for the mitigation of potential
impacts from coastal hazards.
5. Extensive household
consultation regarding the extent of existing coastal hazards and their impact
on the coastal environment was undertaken at this time. Property owners were
given the opportunity to provide both Councils with their views on how coastal
hazard zones should be managed through public meetings and written submissions
over a period of months. A series of meetings were arranged to enable
consultants and Council representatives to present the report and seek feedback
on issues from property owners.
6. In 2005 a joint
Haumoana/Te Awanga Coastal Hazard Working Group consisting of Councillors from
the Hawke’s Bay Regional Council (HBRC) and Hastings District Council (HDC) and
representatives from the Haumoana and Te Awanga communities was formed with the
mandate to work in conjunction with the community towards the long term
management of coastal hazards between Clifton and the Tukituki River mouth.
7. A report was
prepared by HBRC to inform the Working Group. The report entitled Haumoana –
Te Awanga Coastal Hazards – Report on Management options – May 2006, was
presented to the Working Party. It was felt that the report did not adequately
address the social and community costs of the managed retreat option.
8. A further report was
later commissioned from an independent consultant, Environmental Management
Services (EMS). The results of their work was a report entitled ‘Te Awanga – Haumoana
Coastal Erosion Review and Recommendations (March 2009).
9. The recommendations
and content of this report were made public and HDC undertook extensive
consultation throughout the Haumoana and Te Awanga communities with public
information brochures delivered to each ratepayer and a public open day and
meeting held at the Haumoana hall on the 29th of April 2009.
10. It is from that
meeting that the “Walking on Water” group (WOW) were formed in opposition to
the costly groyne field proposal put forward, the preferred options of paying
for the groynes and the alternative option of managed retreat, which at the
time was not well defined or explained.
11. Since 2009 HDC,
supported by HBRC, have been working together with WOW on investigating
alternative sustainable long term solutions to coastal hazards at Haumoana,
including in-depth research into finding a more affordable groyne protection
option which is feasible and potentially consentable under the Resource
Management Act.
12. In order to assist WOW
in understanding the size and complexity of the process, and to assist their
own engagement with the project, HBRC and HDC agreed on 5 February 2010 to
co-fund an independent Resource Management Act (RMA) consultant (Dave Serjeant,
Director of Merestone Ltd) to investigate the following matters:
12.1. The scope of work
and level of detail that would need to be completed sufficient to support
applications for the necessary resource consents.
12.2. Indicative costs
and timeframes to compile the information and specialist consultant advice
required to make and pursue a resource consent application for hard engineering
works.
12.3. The likelihood of
such an application being considered as a nationally significant project which
could be directly referred to the Environmental Protection Agency.
12.4. The feasibility of
pursuing a hard engineering solution along the Haumoana/Te Awanga coast through
the resource consent process given national and regional policies.
13. WoW employed their
own consultant (Moynihan Coastal Consultants Ltd) to design a coastal
protection solution. In order to assess whether this was sufficiently robust
to support an application for resource consent HBRC and HDC decided to subject
the design to a peer review process. The review consisted of two parts.
13.1. A review of the
assumptions about coastal processes and the theory which underpins this design;
whether the design would achieve a reduction in erosion and inundation risk,
and the extent of ‘down-drift’ erosion effects further north along the coast
which might result. This review was undertaken by Derek Todd of Dtec
Consulting Limited (Dtec).
13.2. A review by Opus
International Consultants Limited (Opus) of the structural aspects i.e. the
‘constructability’ of the design and the MCCL cost estimates.
14. This review was
followed by a cost benefit analysis and comparisons with managed retreat and
status quo options (the Covec report).
15. The peer review was
an iterative process which included a caucus meeting in January 2011 between
MCCL, Dtec and Opus.
16. Notwithstanding the
above, the Dtec’s 2011 supplementary report, produced following the caucus
session, had reservations about the following matters which needed to be
resolved.
§ The volume of sediment likely to be in trapped in groyne
fillets,
§ The need for artificial filling of the fillets,
§ The scale of the groyne field required,
§ The scale and significance of the potential down-drift
effects on shoreline position.
17. The Dtec report
recommended that there are ways in which to address these uncertainties in
final design, this work would include the following components:
17.1. An in-depth
analysis of the position, shape, and profile changes at the Tukituki and East
Clive groynes as the basis for determining performance, sediment by-passing,
shoreline rotation, and down drift effects of the proposed groynes.
17.2. A repeat run of the
Tonkin & Taylor UNIBEST shoreline position modelling using the agreed most
appropriate wave approach directions. The modelling would include the East
Clive groynes and the Hastings Sewer outfall, to better determine the likely
long-shore extent and cross-shore scale of the down-drift effects of the
proposed groyne field.
17.3. A desktop sensitivity
analysis of the uncertainty limits of the key parameters such as inshore wave
approach direction, shoreline rotation, and effective groyne length in
calculating the performance and down-drift effects of the proposed groyne
field.
18. In order to progress
the project forward these recommendations were undertaken.
19. HBRC and HDC staff
had Tonkin & Taylor (T&T) undertake the in-depth review of the
position, shape, and profile changes at the Tukituki and East Clive groynes and
sensitivity analysis.
20. Tonkin & Taylor
(T&T) also re-ran their UNIBEST shoreline positioning model, including
several variations to the MCCL groyne proposal, including groyne lengths,
overall groyne numbers and artificial filling ratios. The resultant report
from Tonkin & Taylor following their modelling and analysis was received in
January 2012.
21. The T&T modelling
of the initial MCCL groyne concept, indicated significant downstream erosion
effects would be likely to occur, requiring significant mitigation in the form
of artificial filling of the groyne spacing’s (300,000m3 total) and annual
beach re-nourishment to the north of the groyne field of 10,000m3 / yr for 50
years.
22. HDC had Opus
consultants provide an estimate of the construction and maintenance costs involved
following the T&T modelling and given these recommendations for mitigation.
The result was a major increase in the overall project costs from an original
estimate from Opus in 2010 of $15.2 million (including construction,
maintenance and interest costs) to an estimate now standing at approximately
$40.8 million.
23. Given the significant
costs estimates, WOW returned with a modified groyne proposal by MCCL, proposed
to only cost around $4 million in construction costs, removing a number of
groynes and requiring far less gravel/shingle for mitigation – all up costing
around $6 million.
24. This option is to be
modelled by T&T to determine its effects and then costed out accordingly by
Opus consultants Wellington. If shown to be feasible, an option which costs
less than the $40 million option would be likely to be adopted as the groyne
option for consultation, alongside the alternative of managed retreat.
25. The groyne and
managed retreat options have now been developed and investigated to a point
where there is generally a good level of agreement and understanding of the
costs involved in pursuing each option, as well the relative success of
obtaining RMA consents. The fundamental question that remains is how to fund
the groyne proposal, and what proportion of the costs ought to be funded by the
general HDC ratepayer as opposed to private individual beneficiaries.
26. This is the subject
of a Statement of Proposal under HDCs 2012-2022 Long Term Plan (LTP).
27. In bringing this
proposal to the attention of the public, and interested and affected parties,
HDC began a pre-LTP consultation phase in October 2011. Fourteen Long Term Plan
‘theme papers’ were developed for pre-LTP consultation, with one of those focus
papers being a ‘Coastal Futures’ paper attached in Appendix A, which discusses
the current coastal hazard situation at Haumoana, what’s currently happening,
potential response options and proposed stages of action moving forward into
the future.
28. This theme paper was
distributed to every household in Haumoana and to every out of town owner. A
frequently asked questions (FAQ) sheet was attached and a personal invitation
was also included to an information evening held at the Haumoana School Hall on
the 22nd of November 2011.
29. A hui was also held
with Mana Whenua at the Matahiwi Marae on the 9th of November 2011. The purpose
of this hui was to bring to the attention of Mana Whenua the content of the
Coastal Futures paper and current proposals regarding the groyne field and
managed retreat options.
30. Should it be decided
to advance the groyne solution a Resource Management Act consenting process
will then need to be entered into, with Hastings District Council being the
applicant.
31. While there is
independent Resource Management Act practitioner advice (Serjeant) that the
groyne proposal would stand a reasonably good chance of gaining resource
consent there still remains an element of uncertainty. However before any
decision to proceed to resource consent stage is made an affordable funding
option needs be agreed to by the community for the project.
32. HDCs draft Long Term
Plan and this Statement of Proposal will be considered for adoption at their
meeting on the 15th of March – following that a formal consultation period will
run through 31st March – 4th May. Hearings will then be held from the 30th May
and Council will adopt the 2012/22 LTP on the 28th of June 2012.
Decision Making
Process
1. Council is required to
make a decision in accordance with Part 6 Sub-Part 1, of the Local Government
Act 2002 (the Act). Staff have assessed the requirements contained within this
section of the Act in relation to this item and have concluded that, as this
report is for information only and no decision is to be made, the decision
making provisions of the Local Government Act 2002 do not apply.
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Recommendation
The Asset Management & Biosecurity Committee recommends that
Council receives this report.
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Mike Adye
Group
Manager Asset Management
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Attachment/s
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1View
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Coastal
Futures_HDC
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