Byron Shire Floodplain Risk Management Committee Meeting
A Byron Shire Floodplain Risk Management Committee Meeting of Byron Shire Council will be held as follows:
Conference Room, Station Street, Mullumbimby
Tuesday, 19 February 2019
Phil Holloway Director
Director Infrastructure Services I2019/196
What is a “Conflict of Interests” - A conflict of interests can be of two types:
Pecuniary - an interest that a person has in a matter because of a reasonable likelihood or expectation of appreciable financial gain or loss to the person or another person with whom the person is associated.
Non-pecuniary – a private or personal interest that a Council official has that does not amount to a pecuniary interest as defined in the Local Government Act (eg. A friendship, membership of an association, society or trade union or involvement or interest in an activity and may include an interest of a financial nature).
Remoteness – a person does not have a pecuniary interest in a matter if the interest is so remote or insignificant that it could not reasonably be regarded as likely to influence any decision the person might make in relation to a matter or if the interest is of a kind specified in Section 448 of the Local Government Act.
Who has a Pecuniary Interest? - a person has a pecuniary interest in a matter if the pecuniary interest is the interest of the person, or another person with whom the person is associated (see below).
Relatives, Partners - a person is taken to have a pecuniary interest in a matter if:
§ The person’s spouse or de facto partner or a relative of the person has a pecuniary interest in the matter, or
§ The person, or a nominee, partners or employer of the person, is a member of a company or other body that has a pecuniary interest in the matter.
N.B. “Relative”, in relation to a person means any of the following:
(a) the parent, grandparent, brother, sister, uncle, aunt, nephew, niece, lineal descends or adopted child of the person or of the person’s spouse;
(b) the spouse or de facto partners of the person or of a person referred to in paragraph (a)
No Interest in the Matter - however, a person is not taken to have a pecuniary interest in a matter:
§ If the person is unaware of the relevant pecuniary interest of the spouse, de facto partner, relative or company or other body, or
§ Just because the person is a member of, or is employed by, the Council.
§ Just because the person is a member of, or a delegate of the Council to, a company or other body that has a pecuniary interest in the matter provided that the person has no beneficial interest in any shares of the company or body.
Disclosure and participation in meetings
§ A Councillor or a member of a Council Committee who has a pecuniary interest in any matter with which the Council is concerned and who is present at a meeting of the Council or Committee at which the matter is being considered must disclose the nature of the interest to the meeting as soon as practicable.
§ The Councillor or member must not be present at, or in sight of, the meeting of the Council or Committee:
(a) at any time during which the matter is being considered or discussed by the Council or Committee, or
(b) at any time during which the Council or Committee is voting on any question in relation to the matter.
No Knowledge - a person does not breach this Clause if the person did not know and could not reasonably be expected to have known that the matter under consideration at the meeting was a matter in which he or she had a pecuniary interest.
Participation in Meetings Despite Pecuniary Interest (S 452 Act)
A Councillor is not prevented from taking part in the consideration or discussion of, or from voting on, any of the matters/questions detailed in Section 452 of the Local Government Act.
Non-pecuniary Interests - Must be disclosed in meetings.
There are a broad range of options available for managing conflicts & the option chosen will depend on an assessment of the circumstances of the matter, the nature of the interest and the significance of the issue being dealt with. Non-pecuniary conflicts of interests must be dealt with in at least one of the following ways:
§ It may be appropriate that no action be taken where the potential for conflict is minimal. However, Councillors should consider providing an explanation of why they consider a conflict does not exist.
§ Limit involvement if practical (eg. Participate in discussion but not in decision making or vice-versa). Care needs to be taken when exercising this option.
§ Remove the source of the conflict (eg. Relinquishing or divesting the personal interest that creates the conflict)
§ Have no involvement by absenting yourself from and not taking part in any debate or voting on the issue as if the provisions in S451 of the Local Government Act apply (particularly if you have a significant non-pecuniary interest)
Clause 375A of the Local Government Act 1993 – Recording of voting on planning matters
(1) In this section, planning decision means a decision made in the exercise of a function of a council under the Environmental Planning and Assessment Act 1979:
(a) including a decision relating to a development application, an environmental planning instrument, a development control plan or a development contribution plan under that Act, but
(b) not including the making of an order under Division 2A of Part 6 of that Act.
(2) The general manager is required to keep a register containing, for each planning decision made at a meeting of the council or a council committee, the names of the councillors who supported the decision and the names of any councillors who opposed (or are taken to have opposed) the decision.
(3) For the purpose of maintaining the register, a division is required to be called whenever a motion for a planning decision is put at a meeting of the council or a council committee.
(4) Each decision recorded in the register is to be described in the register or identified in a manner that enables the description to be obtained from another publicly available document, and is to include the information required by the regulations.
(5) This section extends to a meeting that is closed to the public.
Byron Shire Floodplain Risk Management Committee Meeting
3.1 Byron Shire Floodplain Risk Management Committee Meeting held on 29 November 2018
4. Staff Reports
4.1 North Byron Floodplain Risk Management Study and Plan - Update.............................. 5
3.1 That the Byron Shire Floodplain Risk Management Committee Meeting held on 29 November 2018 be confirmed.
3.2 The minutes of the ordinary meeting held on 29 November 2018 were noted and the Committee Recommendations provided to Council for adoption at the Ordinary Meeting held on 28 February 2019
Staff Reports - Infrastructure Services 4.1
Report No. 4.1 North Byron Floodplain Risk Management Study and Plan - Update
Directorate: Infrastructure Services
Report Author: James Flockton, Drain and Flood Engineer
File No: I2019/174
Theme: Infrastructure Services
Emergency Services and Flood Management
Since the previous North Byron Floodplain Risk Management Study and Plan update, WMA Water have been working on finalisation of the flood model calibration.
Initial calibration approval was received from the committee at the last meeting, however, further updates have occurred following investigations into the upstream model layout.
Final calibration approval will be sought at this meeting of the committee.
1. That the Byron Shire Floodplain Management Committee recommends Council approve the calibration results provided in attachment 1 (E2019/10202).
2. That the North Byron Flood Model is fit for purpose and be used for the preparation of the Draft Floodplain Risk Management Study.
The Floodplain Management Committee (FMC) meeting organised for 1st November was postponed due to issues with the hydrological model established as part of the Flood Study.
During the third FMC meeting it was agreed to adopt the ARR 1987 Flood Study model. Given the topographic changes and the addition of new structures in the hydraulic model, it was necessary to confirm that the results of the Flood Frequency Analysis (FFA) at the Durrumbul gauge could be reproduced by the updated models. Whilst attempting to model the design flood events it became apparent that there are more substantial issues with the flood study hydrological model (RAFTS) which limit the ability to match the FFA with these other catchment updates in place.
The primary issue identified is the impact of the storage basin modelled upstream of Williams Bridge. Following review of plan details for Williams Bridge and the topography upstream of Williams Bridge, it was found the dimensions for the basin modelled in the flood study hydrologic model is significantly over estimating the storage and restriction in the area and is not representative of the catchment.
As this model was a calibrated model, a change of this scale requires significant rework and it was necessary to additionally revisit the manning’s ‘n’ roughness coefficient, catchment slope and losses used for each sub catchment.
Preliminary investigation indicated that if the following revisions to the BMT RAFTS model upstream of the Durrumbul gauge are undertaken, the RAFTS model will be more representative of catchment conditions. Additionally calibration of the RAFTS and TULFOW modelling package to historical events and the Flood Frequency Analysis (FFA) at Durrumbul gauge will be possible by:
a) removal of the Williams Bridge storage basin;
b) revising the manning’s ‘n’ roughness coefficient of each sub-catchment, revising the catchment slope of each sub-catchment, and
c) revising losses.
Therefore the following works have been undertaken for the entire North Byron catchment to ensure the RAFTS model is more representative of catchment conditions and to recalibrate the RAFTS and TUFLOW modelling package:
1. Removal of the Williams Bridge storage basin from the RAFTS model;
2. Revised catchment slope in each sub catchment throughout the entire RAFTS model using the QGIS equal area slope tool;
3. Revised manning’s n roughness coefficient in each sub catchment throughout the entire RAFTS model by undertaking a land use analysis and applying the weighted average roughness coefficient in each catchment;
4. Calibrate the modelling package to the March 2017 event;
5. Verify the modelling packages to the January 2012 event
6. Provide calibration memo with accompanying figures, and
7. Calibrate the design events to the FFA at Durrumbul gauge.
This work is now complete and the results are provided within WMA’s memo at attachment 1.
The results show an acceptable model calibration using a model that better resembles the actual catchment conditions.
Considerable effort has been taken to ensure the BMT hydrologic and hydraulic models have received a thorough review as per the project brief. This ensures we have a robust model that can stand up to public scrutiny.
Further investigation is not considered necessary and approval of the model results is recommended.
A rigorous review of the existing flood model is of the utmost importance for the North Byron Floodplain Risk Management Study and Plan. All potential questions around the model accuracy and set up must be removed to ensure it can stand up to public scrutiny.
Over the coming months the Draft Floodplain Risk Management Study document will be prepared and reported to the committee as it progresses. This will include documenting works to date, design flood event mapping, flood hazard and risk mapping, flood levy failure assessment; flood mitigation option assessments and cost benefit analysis of preferred mitigation options.
Other tasks include:
1. Drainage Strategies for Mullumbimby and Brunswick Heads,
2. Land use planning assessment and cumulative development impacts assessment.
3. Emergency Management tasks include Education material, Evacuation Plans and Evacuation Centre Reviews and Flood emergency response classifications.
The Draft Floodplain Risk Management Plan will be prepared once the draft study document has been finalised and received support from the committee.
NSW Councils are expected to prepare Floodplain Risk Management Studies and Plans for flood prone catchments within their local government areas. These documents must be prepared in accordance with State Government Policy.
The NSW Floodplain Development Manual 2005 is the current policy used by State Government for the preparation of such documents.
This project is following the methods prescribed in the NSW Floodplain Development Manual for completing Floodplain Risk Management Studies and Plans.
Resolution of the basin issues did require a project variation of $ 16,760 ex GST. However a grant variation has been submitted to the Office of Environment and Heritage to obtain two thirds funding towards this variation. The impact to Council will be $5,587.
Consultation and Engagement
The Office of Environment and Heritage have been consulted between FMC meetings to ensure they are aware of where the project has been heading and why a delay has occurred.