Bray Park Weir Tidal Protection Project

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Alert for deployment of barrier to protect weir

There is a continuing risk that Bray Park Weir, which supplies raw water for the Tweed Shire, may be overtopped by tidal salt water during high tide and sea level anomaly events for the foreseeable future. Council monitors this risk and acts to protect the weir when necessary by installing concrete blocks to narrow the weir and temporarily raise the water level in the weir pool. The blocks are removed when the risk has passed. Residents who want to receive an email alert ahead of Council installing concrete blocks to temporarily protect the weir should register their name and email address by emailing wateradmin@tweed.nsw.gov.au (Subject: Weir Alert). Worst-case, Council will provide three hours’ notice of a temporary raising of the weir wall.

About

A combination of high tides plus an unforeseen sea level anomaly caused Bray Park Weir to be overtopped on the nights of the 21 and 22 August 2017.

The overtopping occurred at a time of low flow in the Tweed River and the consequence was salt water ingress into the Bray Park Weir pool.

The salt water ingress caused the raw water provided to the Bray Park Water Treatment Plant to be contaminated. Consequently, the contaminated salt water went into the Tweed drinking water supply.

At no time was it a risk to human health.

This issue will become worse over time with the impact of climate change and subsequent increases in sea levels.

This project seeks to identify and assess a range of options to reduce the risk of salt water ingress into Bray Park Weir both now and into the future and to identify a preferred option for Council’s consideration.

The preferred option may be a engineered or non-engineered solution or mix of solutions.

Alert for deployment of barrier to protect weir

There is a continuing risk that Bray Park Weir, which supplies raw water for the Tweed Shire, may be overtopped by tidal salt water during high tide and sea level anomaly events for the foreseeable future. Council monitors this risk and acts to protect the weir when necessary by installing concrete blocks to narrow the weir and temporarily raise the water level in the weir pool. The blocks are removed when the risk has passed. Residents who want to receive an email alert ahead of Council installing concrete blocks to temporarily protect the weir should register their name and email address by emailing wateradmin@tweed.nsw.gov.au (Subject: Weir Alert). Worst-case, Council will provide three hours’ notice of a temporary raising of the weir wall.

About

A combination of high tides plus an unforeseen sea level anomaly caused Bray Park Weir to be overtopped on the nights of the 21 and 22 August 2017.

The overtopping occurred at a time of low flow in the Tweed River and the consequence was salt water ingress into the Bray Park Weir pool.

The salt water ingress caused the raw water provided to the Bray Park Water Treatment Plant to be contaminated. Consequently, the contaminated salt water went into the Tweed drinking water supply.

At no time was it a risk to human health.

This issue will become worse over time with the impact of climate change and subsequent increases in sea levels.

This project seeks to identify and assess a range of options to reduce the risk of salt water ingress into Bray Park Weir both now and into the future and to identify a preferred option for Council’s consideration.

The preferred option may be a engineered or non-engineered solution or mix of solutions.

  • Impacts of climate change on sea level and water levels in the Tweed Estuary

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    21 Mar 2019

    21 March 2019

    Council, in a project separate from the Bray Park Weir Tidal Protection Project, engaged consultant BMT Global to identify the impacts of climate change on sea level and water levels in the Tweed Estuary. The consultant also considered sea level anomalies.

    The consultant’s report, Tweed Estuary Tidal Inundation Assessment and Mapping, while still in draft form does contain relevant information on predictions for sea level rise.

    Please see the document BMT Global Excerpt in the Documents Library on this page.


  • Consultant kicks off salt water protection investigation

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    11 Feb 2019
    supporting image

    12 February 2019

    Specialist water consultant Hunter H2O has been engaged to assess options to protect the Tweed District Water Supply from salt water contamination.

    In May last year, Council formed a Project Reference Group to assist it to find a solution to the salt water contamination issue. The group identified a range of options, which the consultant will now assess. Those options include both engineering and non-engineering solutions to the problem.

    The Bray Park Weir Tidal Protection Project Reference Group comprises a wide range of community interests including landowners, dairy farmers, canegrowers, businesses that use water as a critical input, ratepayers, recreational fishers and two elected councillors. Throughout, all PRG members have stated that they also speak for the environment.

    Last week the consultants met with members of the Project Reference Group to clarify the 10 options identified by the group as likely short-term fixes warranting further investigation.

    The consultants have been invited to propose up to three further options for investigation based on their extensive knowledge and expertise.

    Hunter H2O will investigate all the options against a set of criteria, which include maintaining the Tweed’s high water quality and security of supply as well as numerous environmental, social and legal considerations.

    At the conclusion of its investigations in about four months, Hunter H2O will report back to the Project Reference Group providing them with all the information they need to identify a preferred option to recommend to Council for adoption.

    Above: Hunter H2O Project Manager Anne-Marie Turnbull with members of the Project Reference Group from left Dr Pascal Scherrer (Southern Cross University facilitator), Glen Jones, Simon Fitzpatrick, Project Manager Rob Siebert, Hunter H2O Engineer Matthew Bloomfield and Michael McDonald.


  • Council gets funds to engage independent consultant

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    29 Aug 2018

    Wednesday 29 August 2018

    Today Council received $100,000 in funding under the Restart NSW – Safe and Secure Water Program to assist Council to engage an independent consultant to identify and assess options to protect the Tweed’s Water Supply as recommended by the Project Reference Group.

    Member for Lismore Thomas George made the funding announcement at Bray Park Weir in company with Tweed Shire Council Managing Director Troy Green, Project Manager Rob Siebert and PRG member Councillor Pryce Allsop.

    Council now has to formally accept the funding offer.

    The next meeting of the PRG will be held on 19 September. At this meeting, the PRG will identify options to be assessed by the independent consultant and the assessment criteria to be used.


  • University lecturer to facilitate weir discussions

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    11 May 2018

    11 May 2018

    Southern Cross University Lecturer Dr Pascal Scherrer will facilitate the meetings of the Bray Park Weir Tidal Protection Project Reference Group, with the first meeting scheduled for Friday 25 May.

    Dr Scherrer has extensive experience in facilitation in his core role as a researcher and teacher in the School of Business and Tourism at the Lismore campus.

    He has successfully contributed to the implementation of more than 20 industry, university and government projects.

    Dr Scherrer received two awards for community engagement and community engagement research for his role in leading the NSW National Parks and Wildlife Service engagement on visitor management issues at Wollumbin (Mt Warning).

    He also was the lead investigator on a project assessing Rottnest Island’s sustainable visitor capacity, facilitating discussions between key experts, opposing interest groups, managers and operational staff. The project successfully delivered a mandate to implement many positive changes with respect to visitor infrastructure.

    His aim in facilitating the Project Reference Group meetings will be to accurately reflect the voices of the membership and work towards consensus on ways to mitigate the risk of contamination of the Tweed District Water Supply by salt water.


  • Bray Park Weir protection group finalised

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    06 Apr 2018

    Friday 6 April 2018

    Council last night finalised the membership of a project reference group to help identify and assess solutions to protect Bray Park Weir from future tidal inundation.

    The group of 12 comprises 10 nominees from the community, plus councillors Mayor Katie Milne and Pryce Allsop.

    It is anticipated that the group will meet between four and six times before it can present to Council a preferred option or mix of options to mitigate the risk of saltwater ingress into the Bray Park Weir pool.

    Nineteen nominations were received from the community to join the group, with Council expanding the community representation from eight (8) to ten (10) members to accommodate the strong interest in this issue.

    The successful community nominees were:

    · Ken Baker – neighbouring landowner to the weir property

    · Peter Robson – representing recreational river users

    · Brett Sander – adjacent residential property owner and engineer

    · Corey Crosthwaite – landowner representing the Upper Weir Property Association

    · Neil Baker – landowner representing the Upper Weir Property Association

    · Glen Jones – landowner representing landowners south of Slippery Crossing, along Solomons Road to Old Lismore Road south

    · Peter Tomsett – landowner and retired engineer representing the Lower Oxley Land Owner Group

    · James Perrin – representing critical water user Stone and Wood brewery and other businesses dependent on a high-quality water supply

    · Simon Fitzpatrick - representing recreational fishers and fish habitat conservation, and

    · Michael McDonald – representing Tweed Canegrowers.

    Anyone with an interest in this project is asked to contribute their ideas on the options to mitigate the risk of saltwater inundation into the Bray Park Weir pool by contacting one of the above members of the Project Reference Group.

    Alternatively, you can register online at https://www.yoursaytweed.com.au/BrayParkWeir to provide direct input to the project team.

    The contact details for all Project Reference Group members can be found on the project page on Your Say Tweed.


  • Bray Park Weir tidal protection Project Reference Group seeks nominations

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    08 Jan 2018

    22 December 2017

    Nominations are now being accepted for representatives of stakeholder groups to join the Bray Park Weir Tidal Protection Project Reference Group.

    Successful nominees will join a project reference group considering options to mitigate the ingress of salt water into the Tweed Shire water supply, as occurred when a combination of high tides plus an unforeseen sea level anomaly caused the weir to be overtopped twice in August 2017.

    Tweed Shire Council Director Engineering David Oxenham said this is an issue which will become more of a frequent concern over time due to the impact of climate change and subsequent increases in sea levels.

    “We have already had a number of stakeholders register their interest in being part of this group and they have been contacted about nominating,” Mr Oxenham said.

    “We now want to make sure anyone else who might have something to contribute has an opportunity to put their name forward.

    “This project seeks to identify and assess a range of options to reduce the risk of salt water ingress into Bray Park Weir, both now and into the future, and to identify a preferred option for Council’s consideration.”

    The events in August, which at no time posed any risk to human health, came at a time when river flows were low due to low rainfall levels in the catchment and Council staff will monitor conditions during upcoming peak high tide periods.

    If staff asses there to be a risk a number of temporary measures have been adopted which will protect the weir pool.

    These measures involve concrete blocks and sandbags, which can be put in place when required and left for a week at a time, but the project reference group will look into a more permanent solution.

    A page dedicated to the Bray Park Weir Tidal Protection Project has been set up on the Your Say Tweed community engagement portal at yoursaytweed.com.au.

    The page includes the latest project news, key dates and a document library including the nomination form for the project working group.

    The library also includes the terms of reference for the group along with a number of reports about the original inundation.

    Nominations close on Wednesday 31 January 2018. Anyone who may require a nomination form but cannot access Your Say Tweed can contact Project Officer Sandra Freeman on 02 6670 2285 from Monday 8 January 2018.


  • Council seeks funds to protect weir as high tides on way

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    05 Dec 2017

    Friday 1 December 2017

    Council has applied for funding to begin investigating what it can do to protect Bray Park Weir pool from being contaminated with salt water due to overtopping as it gears up for another run of high tides from Sunday onwards.

    “We have applied for funds under the NSW Government’s Safe and Secure Water Program to develop the scope of our proposed Bray Park Weir Tidal Protection Project while at the same time getting ready for a run of high tides that are predicted to again overtop the weir wall,” Manager Water and Wastewater Anthony Burnham said.

    “We’re also calling for nominations from the community to join a Project Reference Group to help us identify and assess what options we have to protect the weir pool. We would particularly like nominations from landowners with properties fronting the river and business owners who rely on a high-quality water product.”

    The final membership of the Project Reference Group will be decided by Council next year.

    To nominate for the Project Reference Group, register online at http://www.yoursaytweed.com.au/BrayParkWeir.

    Meanwhile, Council will have staff on call this weekend and early next week to monitor the effects of the high tides and respond if needed.

    “Thankfully we currently have strong flows from the upper catchments due to the recent run of wet weather which will help hold back the high tides so we will only need to sandbag the wall if these flows drop significantly,” Mr Burnham said.

    Council also was sampling the river water downstream to determine what levels of salt were present and what concentrations could be expected if the weir wall does overtop next week.

    “Salt water concentrations measured at Murwillumbah’s Commercial Road Boat Ramp on Thursday were very low so any overtopping of the weir is unlikely to adversely affect our water supply.

    “Nevertheless, we will have staff monitoring the tides closely and standing by to act to prevent salt getting into the shire’s drinking water supplies.”


  • Precautionary water restrictions placed on Tweed Shire

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    07 Nov 2017

    22 August 2017:

    Immediate water restrictions have been put in place in Tweed Shire as a precaution due to salt water getting into Bray Park Weir overnight.

    The restrictions are precautionary only, with the issue deemed to be aesthetic. However, Council is contacting the North Coast Public Health Unit to advise it of the situation and recommends people with medical conditions, such as those using dialysis, contact their usual medical provider for advice.

    Residents are asked NOT to use any water for outdoor uses, such as gardening, washing cars etc.

    At this stage, indoor water use and commercial operations are not restricted.

    Residents should also be alert not to use the water on salt-sensitive plants, such as avocadoes, or in fresh-water fish tanks.

    The restrictions are likely to be in force for 24 hours to two days as Council works to rid the weir of the salty water.

    Tests done this morning by Council’s Tweed Water Laboratory confirmed total dissolved solids of 620mg/litre at the weir. The Australian Drinking Water Guidelines rule <600mg/litre as being of ‘good’ quality; 600-900mg/litre as being of ‘fair quality; and, >1200mg/litre as being of ‘unacceptable’ quality.

    “We know that Murwillumbah water is most affected but ask all shire residents to restrict water use at this stage,” Manager Water and Wastewater Anthony Burnham said.

    “Alarms at the Bray Park Water Treatment Plant alerted us to the issue about 8 o’clock this morning. While we will investigate the cause further, at this stage I understand the salt water ingress resulted from a higher than predicted tide. Council’s normal operating procedures are to place sandbags on the weir wall to raise the height of the wall in these events.

    “As well, the natural flow of the Tweed River normally works against the tide to keep salt water out of the weir but current river flows are low.”

    Residents are advised not to drink their tap water if it tastes salty but instead use bottled water.

    Council will provide an update on the situation about noon today.

    The drinking water for Uki and Tyalgum is not affected.


  • Pipe scouring underway to take salt out of water main

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    07 Nov 2017

    23 August 2017, 12.30pm:

    Council has begun scouring the mains pipe from the Bray Park Water Treatment Plant to King Street, Murwillumbah, to remove the likely highest salt concentrations from the top end of the Tweed water reticulation system.

    A dredge is expected to arrive on site at Bray Park Weir late this afternoon to begin pumping out the heavier salty water from the bottom of the weir as a continual release from Clarrie Hall Dam refreshes with good water at the top of the pool.

    Intake baffles at the weir have been closed at deeper depths and the main pump has been set to run at minimal capacity to reduce – as much as possible – the draw of salty water from the bottom of the pool. A smaller floating surface pump has been installed and is running at maximum capacity to draw good water from the top of the pool into the treatment plant.

    “With these actions in place to reduce the salty water within the reticulation system and draw in as much ‘good’ water as possible, we have started to dump about one-fifth of the poorer quality water ready for release into the reticulation system in anticipation of producing better quality water tonight,” Manager Water and Wastewater Anthony Burnham said.

    “Still, all going well, it is going to be at least three to four days before we get the salty taste out of the water and at least a week before we will be able to produce our normal high-quality drinking water.”

    Further investigation into the climatic conditions leading up to the overtopping of the weir wall on Monday night confirms a perfect storm of events.

    Bureau of Meteorology and tide data confirms a run of higher-than-expected tides up to 420mm above predicted levels; higher salinity levels offshore; and, warmer ocean temperatures.

    Mr Burnham thanked Tweed residents for assisting by minimising their use of water.

    “Hospital Hill reservoir is holding relatively steady at this stage which shows people are responding to our request to minimise water use. This effectively buys us time to rid the system of salt before the demand for water forces us to release more poorer-quality water into the system.”

    The Australian Drinking Guidelines advise that the current salt levels are not harmful to human health. However, residents are advised to use bottled water for drinking if the taste of the water is too unpalatable.

    The water at Uki and Tyalgum is not affected and no restrictions apply in those villages.


  • Council flushing salt water from weir

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    07 Nov 2017

    22 August 2017:

    Council has released water from Clarrie Hall Dam to flush salt water out of Bray Park Weir after high tides overtopped the weir wall on Monday night.

    The flush of water from the dam should reach the weir by 5pm today.

    More water tests will be conducted about 10 o’clock tonight and if the release has sufficiently reduced the salt content in the weir, the reticulated water supply will be switched back on and should be recharged by tomorrow morning allowing water restrictions to be lifted.

    If the release from the dam does not sufficiently flush the weir pool, a second release will occur tomorrow morning, meaning restrictions will remain in place longer.

    Council also has drained the salt-charged water from the Bray Park Water Treatment Plant and water mains. It has not drained the affected Hospital Hill reservoir in Murwillumbah as any residual salty water will dilute once fresh water enters the system.

    “This morning’s release from the dam also should be sufficient to hold back any salt water from tonight’s high tide, which is expected to be 200mm above predictions,” Manager Water and Wastewater Anthony Burnham said.

    Tidal data recorded at the entrance to the Tweed River confirms that since Saturday actual tides have been up to 380mm higher than the predicted tides. The predicted tides at Bray Park were to be 1.79 (Monday pm) and 1.81m (Tuesday am) respectively. The actual tides were 2.17m (Monday pm) and 2.11m (Tuesday am).

    “Council uses tide prediction information available through the Bureau of Meteorology to manage the risk of the weir wall being overtopped by salty water. Plus, the natural flow of the Tweed River also helps to hold back a king tide.

    “Last night’s incident occurred because the predicted tides, together with the fact that the natural water flow from the Tweed River was still going downstream over the weir wall, informed Council’s decision that sandbagging to raise the height of the weir wall was not warranted.

    “In the past, we have had no issues with tides of 1.87m but, this time, the downstream river flows were not strong enough to hold back the salt water.”

    The amount of salt water in the weir is significant but not unacceptably high. The Australian Drinking Water Guidelines rule <600mg/litre as being of ‘good’ quality; 600-900mg/litre as being of ‘fair quality; and, >1200mg/litre as being of ‘unacceptable’ quality. The water in the weir was tested this morning and the confirmed total dissolved solids were 620mg/litre.

    Council has advised the North Coast Public Health Unit of the situation.

    People with medical conditions, such as those using dialysis, are advised to contact their usual medical provider for advice.

    Residents are asked NOT to use any water for outdoor uses, such as gardening, washing cars etc.

    Residents should also be alert not to use the water on salt-sensitive plants, such as avocadoes, or in fresh-water fish tanks.

    At this stage, indoor water use and commercial operations are not restricted. The drinking water supplies of Uki and Tyalgum are not affected.