COVER REPORT - COMMITTEE MEETING
Title of Report:
Tidal Barrier Pre-Feasibility Study Consultation
Meeting of:
Infrastructure, Transport and Environmental (ITE) Committee
Date of Meeting:
Thursday 8 October 2015
Date Required by Democracy
Monday 21 September 2015
Services:
Community Board Consultation: Needed:
N
Complete:
Y
Meeting held
Public Excluded
N if
PUBLIC EXCLUDED the section below
MUST be completed
REASON UNDER ACT
SECTION
PLAIN ENGLISH REASON
WHEN REPORT CAN BE
RELEASED
No of Attachments (must be cited in report) : Six Description of Attachments:
Written submissions from:
Canterbury Earthquake Recovery Authority
Environment Canterbury
Avon-Heathcote Ihutai Trust
Christchurch Estuary Association
Avon Otakaro Network
Southshore Residents' Association
Confirmation of Statutory Compliance
Compliance with Statutory Decision-making Requirements (ss 76 - 81 Local Government Act 2002).
(a) This report contains:
(i) sufficient information about all reasonably practicable options identified and assessed in terms of their
advantages and disadvantages; and
(ii) adequate consideration of the views and preferences of affected and interested persons bearing in
mind any proposed or previous community engagement.
(b) The information reflects the level of significance of the matters covered by the report, as determined in
accordance with the Council's significance and engagement policy.
Name and title of signatories
Signature
Date
Prepared by
Sylvia Maclaren
21/09/2015
Project Manager
Approved by
Peter Langbein
21/09/2015
Finance Manager
Approved by
Keith Davison
21/09/2015
Storm water and Land
Drainage Rebuild
Approved by
David Adamson
21/09/2015
Executive Leadership Team
Member
Tidal Barrier Pre-Feasibility Study Delivery
Reference:
TRIM 15/1127524
Contact:
Keith Davison
[email address]
03 941 8071
1.
Purpose of Report
1.1.
The Avon-Heathcote Tidal Barrier Pre-Feasibility Study was tabled at the ITE Committee on 6
August 2015, and made publically available online on the same day. The recommendations
of the committee to Council were that:
1.1.1. That the information in (the) report be received.
1.1.2. That the Council seek input from CERA, ECan, Ngai Tahu and the Avon Ihutai Estuary
Trust and the Christchurch Estuary Association as partners and stakeholders on (the)
technical report and its implications.
1.1.3. That staff report back their recommendations to the next ITE meeting.
1.2.
This report is to close out recommendation 1.1.2 by providing the responses to the input
requested. It is also to seek a recommendation to Council as to whether to proceed to a full
feasibility study for the tidal barrier.
2.
Background
2.1.
The barrier is just one of a number of flood management options the Land Drainage Recovery
Programme (LDRP) and Council Strategy and Planning Group are investigating as flood
mitigation measures for Christchurch.
2.2.
The purpose of the pre-feasibility study was to understand whether a tidal barrier was worthy
of further consideration and if the Council would be justified in conducting a full feasibility
assessment.
2.3.
The study states that a barrier is technically feasible, and would be within the capabilities of
New Zealand contractors at a build cost in the range of $300 - $350M with operations and
maintenance a further $2 - $7M per year. It will result in substantial impacts on the estuary
environment.
2.4.
A tidal barrier would not remove the need for some additional defences. The likely costs of
these combined with a barrier in the present day scenario are more expensive than potential
alternatives (Table 1). A tidal barrier could be more cost effective in the long term as sea level
rise eventuates.
Table 1. Summary of costs with / without a tidal barrier
Present day climate
1m sea level rise
Alternative
Alternative
Tidal barrier
Tidal barrier
engineering solution
engineering solution
$211M
$430M
$571M
$545M
ITE Committee - 8 October 2015 - Tidal Barrier Pre-Feasibility Study Consultation
2.5.
The pre-feasibility tidal barrier study only considered two climate scenarios, the present day
scenario and 1m sea level rise scenario. It did not determine if there is an intermediate point
between these scenarios whereby a tidal barrier becomes cost effective.
2.6.
Previous external communications during the preparation of the report had included
workshops with ECan for early evaluation and issues identification, information sessions with
Te Ngāi Tūāhuriri Rūnanga and the Avon-Heathcote Ihutai Estuary Trust, and the sending of
a memo on 13 July 2015 to the Hagley-Ferrymead and Burwood-Pegasus Community Boards
informing them of the study. CERA was updated with copies of the draft and final report as
they were received. Feedback was also received through the Long Term Plan (LTP) process.
3.
Commentary
3.1.
In response to the ITE Committee's recommendations the Mayor's office prepared a letter to
seek input from the nominated stakeholders. This letter stated Council staff would be in
touch to arrange meetings with representatives of each organisation to discuss the study and
receive feedback.
3.2.
From this, meetings were held with CERA, the Avon-Heathcote Ihutai Estuary Trust, and the
Christchurch Estuary Association. A meeting with Ngai Tahu was scheduled for 29 September
2015 (after the submission of this officer's report) so will be reported on verbally at the ITE
Committee meeting. ECan declined a meeting request.
3.3.
In addition, Council staff were requested to present to the Hagley/Ferrymead Community
Board and did so at the meeting of 14 September 2015.
3.4.
To summarise the range of views, written responses were received from all nominated
partners / stakeholders. These responses are attached. Additional unsought feedback was
received from Avon Otakaro Network and Southshore Residents' Association, and these
submissions are also attached.
3.5.
Feedback has been mixed with proponents for, against and neutral towards progression to a
full feasibility study on a tidal barrier. Generally, there has been a level of concern that earlier
and more in-depth consultation did not occur.
3.6.
Commentary from the submissions, and from both GHD and Jacobs (who provided a peer
review), propose a city-wide flood management strategy would provide a better option. This
would include an assessment of all the possible engineering and non-engineering options.
This could include a tidal barrier at a high level without the additional information provided
by a full feasibility study.
4.
Recommendation
4.1.
That a full feasibility study on a tidal barrier does not proceed at this stage under the Land
Drainage Recovery Programme.
4.2.
That the information in the pre-feasibility report on a tidal barrier be considered as one of
the engineering options for flood protection in the development of the Council's Three
Waters Strategy.
4.3.
The Council continue to work closely with CERA on the options for flood plain management
as part of the technical work on the future use of the Residential Red Zone.
ITE Committee - 8 October 2015 - Tidal Barrier Pre-Feasibility Study Consultation
Signatories
Author
Sylvia Maclaren
Project Manager
Approved By
Peter Langbein
Finance Manager
Keith Davison
Unit Manager
David Adamson
Director
[Council 28 May 2014 – Open Agenda]
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