gordonbrook dam emergency action plandata.dnrm.qld.gov.au/eap/gordonbrook-eap.pdf · 2020. 7....

GORDONBROOK DAM Emergency Action Plan Dam ID 0657 Shailers Road Location: Lat. -26.434530° Long. 151.734110°

Prepared by South Burnett Regional Council Version 6.1 June 2020

WIDTJText Box

Approved by the delegate of the Chief Executive, Department of Natural Resources, Mines and Energy until 1 August 2021.

GORDONBROOK DAM Emergency Action Plan

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TABLE OF CONTENTS DEFINITIONS ..................................................................................................................................... iv 1 INTRODUCTION .................................................................................................................................................. 1

1.1 PURPOSE ............................................................................................................................................................ 1 1.2 SCOPE ................................................................................................................................................................. 1 1.3 DAM OWNER RESPONSIBILITIES ......................................................................................................................... 1 1.4 EAP REVIEW AND APPROVAL FLOW PLAN ........................................................................................................... 2 1.5 EAP ACTIVATION LEVELS ..................................................................................................................................... 4 1.6 NOTIFICATIONS .................................................................................................................................................. 4 1.7 ROLES AND RESPONSIBILITIES ............................................................................................................................. 7 1.8 EAP DAM INCIDENT MANAGEMENT TEAM ......................................................................................................... 7

2 DAM DETAILS ..................................................................................................................................................... 9

2.1 GENERAL INFORMATION ABOUT GORDONBROOK DAM ..................................................................................... 9 2.2 SPILLWAY ADEQUACY ....................................................................................................................................... 11 2.3 POPULATION AT RISK ........................................................................................................................................ 11 2.4 GENERAL DAM ARRANGEMENT ........................................................................................................................ 12 2.5 DAM INSPECTIONS AND MONITORING ............................................................................................................. 13

3 DOCUMENTATION AND REPORTING ................................................................................................................. 14

3.1 INCIDENT LOG................................................................................................................................................... 14 3.2 REPORTING ....................................................................................................................................................... 14

4 EMERGENCY EVENTS AND ACTIONS ................................................................................................................. 15

4.1 EVENT ACTIVATION LEVELS ............................................................................................................................... 15 4.1.1 DAM HAZARD TRIGGER AND ACTIVATION LEVELS .......................................................................................... 16 4.2 NON‐FLOOD RELATED HAZARD EVENTS ............................................................................................................ 17

5 DAM HAZARD & EMERGENCY EVENT ACTIONS ................................................................................................. 18

5.1 STORAGE LEVEL IS AT RL 392.0 (+0.5M ABOVE SPILLWAY CREST LEVEL) ........................................................... 18 5.2 STORAGE LEVEL IS AT RL 392.4 (+0.9M ABOVE SPILLWAY CREST LEVEL) ........................................................... 19 5.3 STORAGE LEVEL IS AT RL 393.0M (1.5M ABOVE SPILLWAY CREST LEVEL) ............................................................ 20 5.4 STORAGE LEVEL IS AT RL 394.0 (2.5M ABOVE SPILLWAY CREST LEVEL) AND FURTHER RAIN IS FORECAST .......... 21 5.6 STORAGE LEVEL RISES ABOVE RL 397.7M (0.5M BELOW DAM CREST LEVEL) AND OVERTOPPING IS IMMINENT . 24 5.7 STORAGE LEVELS DROPPING AND NO FURTHER RAIN PREDICTED ..................................................................... 26 5.8 INCREASE IN SEEPAGE OR NEW AREA OF SEEPAGE IS OBSERVED IN THE DOWNSTREAM EMBANKMENT .......... 27 5.9 ANOMALIES IN PIEZOMETER READINGS ............................................................................................................ 28 5.10 EARTHQUAKE IS REPORTED IN THE VICINITY OF THE DAM .............................................................................. 29 5.11 MOVEMENT OF DAM EMBANKMENT ............................................................................................................. 30 5.12 DAMAGE TO DAM OR SPILLWAY (INCLUDING OBJECTS CRASHING INTO DAM AND TERRORIST INCIDENTS) .... 31

6 EMERGENCY ACTION PLAN GENERAL INFORMATION ........................................................................................ 33


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6.1 EAP EXERCISES & TESTING ................................................................................................................................ 33 6.2 EAP TRAINING ................................................................................................................................................... 33 6.3 EAP EDUCATION ............................................................................................................................................... 33

APPENDIX A ACCESS TO GORDONBROOK DAM ................................................................................................... 34

APPENDIX B STORAGE CAPACITY ......................................................................................................................... 36

APPENDIX C GORDONBROOK DAM CATCHMENT AND FLOOD HYDROLOGY ......................................................... 40

APPENDIX D SAFETY INSPECTIONS ...................................................................................................................... 50

APPENDIX E INCIDENT LOG FORM ....................................................................................................................... 52

APPENDIX F COMMUNICATION CONTACT LIST .................................................................................................. 55

APPENDIX G HAZARD INUNDATION MAPS .......................................................................................................... 62

APPENDIX H ALERT AND EMERGENCY NOTIFICATION DETAILS ............................................................................. 72


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DEFINITIONS "Act" means the Water Supply (Safety and Reliability) Act 2008;

“AEP” means Annual Exceedance Probability “AFC” means Acceptable Flood Capacity

"AHD" means Australian Height Datum;

“AMTD” means Adopted Middle Thread Distance "ANCOLD" means Australian National Committee on Large Dams;

“BOM” means Bureau of Meteorology

"Controlled Document" means a document subject to managerial control over its contents, distribution and storage. It may have legal and contractual implications;

“DDC” means District Disaster Coordinator “DDMG” means District Disaster Management Group "Dam" means the dam to which this document applies, that is Gordonbrook Dam which

is owned by South Burnett Regional Council – “Dam Hazard" means a reasonably foreseeable situation or condition that may cause or

contribute to the failure of the dam, if the failure of the dam may cause harm to people or property;

"Dam Hazard Event " means event arising from a dam hazard if the dam owner plans to warn people who may be harmed, or whose property may be harmed, about the event under the dam owner’s emergency action plan; but a coordinated response with one or more relevant entities is unlikely to be required.

Dam Emergency Event” means event arising from a dam hazard if person or property may be harmed because of the event and any of the following apply— (i) a coordinated response involving 2 or more of the relevant entities is likely

to be required to respond to the event; (ii) the event may arise because of a disaster situation declared under the

Disaster Management Act; (iii) an entity performing functions under the State disaster management plan

may, under that plan, require the owner of the dam to give the entity information about the event.

"Dam Safety Regulator" means Chief Executive, Department of Natural Resources, Mines and Energy Water Supply Division

"Dam Safety Consultant" means a consultant engaged for the purposes assessing the dam structure "Data Book" means Data Book for a Dam, which is to include all pertinent records and history

relating to the dam and must encompass the documentation of investigation, design, construction, operation, maintenance, surveillance, monitoring and any remedial work undertaken on the dam.

“DCF” means Dam Crest Flood "DNRM&E" means the Queensland Department of Natural Resources Mines & Energy;

"EAP" means Emergency Action Plan for a Dam;

“EER” means Emergency Event Report;

"EL" means elevation in metres Australian Height Datum;

“FF” means Failure Flood

"FSL or Full Supply Level" means the level of the water surface when the reservoir is at maximum operating level, excluding periods of flood discharge;

“DIMT” means Dam Incident Management Team

“LDC” means SBRC Local Disaster Coordinator


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“LDCC” means Local Disaster Coordination Centre

“LDMP” means Local Disaster Management Plan

“LDMG” means Local Disaster Management Group

“ML” means Megalitre or 1,000,000 Litres

"O&M Manual" means Operations and Maintenance Manual for a Dam;

“PMF” means Probable Maximum Flood;

“PMP” means Probable Maximum Precipitation;

“PAR” means Population at Risk;

"Referable Dam" means a dam that requires a failure impact assessment under the Act and the assessment states that the population at risk from a failure of the dam is two persons or greater;

"SBRC" means the South Burnett Regional Council.

"SOP" means SBRC Standard Operating Procedure for a Gordonbrook Dam;

“Treatment Plant Operator” means a person who is trained operates the Gordonbrook Water Treatment

Plant


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1 INTRODUCTION 1.1 PURPOSE

The purpose of this Gordonbrook Dam EAP is:

• to minimise the risk of harm to persons or property if a dam hazard event or emergency event for the dam happens; • to identify dam hazards that could occur at Gordonbrook Dam and the area likely to be affected for each hazard; • to prescribe emergency actions taken by SBRC and operating personnel in identifying and responding to dam

hazards and notifying relevant entities.

The EAP specifically describes the coordination of these necessary actions by SBRC and its officers to provide timely notification to Police, Emergency services, Disaster Management groups and Population at Risk in the event of a potential emergency event at Gordonbrook Dam. 1.2 SCOPE

The Gordonbrook Dam EAP covers:

• dam hazards evaluated within Dam Program Safety Management; • details about the dam that are relevant to a dam hazard; • identification of circumstances that indicates a material increase in the likelihood of a dam hazard event or

emergency event; • triggers for activation of a tiered response to dam hazard event or emergency event; • roles and responsibilities in responding to a dam hazard event or emergency event; • notification, warning and communication protocols; • inspection, monitoring and reporting protocols during emergencies; • other relevant information that may assist with identifying the area affected by a dam hazard event; and/or • an emergency event and the management of such.

1.3 DAM OWNER RESPONSIBILITIES

The following outlines the responsibilities of a dam owner:

• Develop an EAP in consultation and collaboration with local government and disaster management group/s who may be affected by a dam hazard identified in the plan.

• Provide a copy of the EAP to each local government and disaster management group who may be affected by a dam hazard identified in the plan. These stakeholders have 30 business days to review the plan. The local government must provide a notice back to the dam owner within the 30 business days, the disaster management group may provide a notice, however it is not compulsory.

• The local government assessment notice of the EAP against the Disaster Management Plan and all notices received by the dam owner from the chair/s of the district (disaster management) group/s must be provided to the Chief Executive, Department of Natural Resources, Mines and Energy Water Supply Division at the time of EAP submission.

• Assess the EAP against the outcomes of the Queensland Emergency Management Assurance Framework (https://www.igem.qld.gov.au/assurance-framework). The Emergency Management Prioritisation Tool (https://www.igem.qld.gov.au/assurance-framework/emergency-management-prioritisation-tool) may be utilised for this purpose.

• Submit the EAP to the Chief Executive, Department of Natural Resources, Mines and Energy Water Supply Division for assessment. The EAP must be accompanied by each notice given by a local government (must have), disaster management group for the plan (if received) and any notice responses by the dam owner.


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• Maintain and update documents annually (before 1 October each year) • Distribute current approved EAP to all parties listed in the distribution list. • Respond in accordance with the approved EAP in all dam relevant incidents. • Activate the EAP and maintain an incident log (including visual inspection of the dam and any notifications that

have been made). • Provide timely and accurate notifications to all relevant parties mentioned in the notification list in a relevant dam

hazard event or emergency event. • Report all incidents and failures in writing to the Dam Safety Regulator within forty-eight (48) hours of becoming

aware of the incident or failure. • Prepare an EER and submit to the Dam Safety Regulator within 30 business days after the end of the emergency

event. • Ensure the PAR have an appropriate evacuation plan in the event of a dam failure. • Ensure the PAR have an understanding of the purpose of the warning and notifications in the event of a dam

emergency or dam hazard. • Ensure appropriate training for all personnel with responsibilities under the EAP. • Undertake periodic testing of EAP to ensure telephone numbers are correct and the notification priority list is logical.

Make appropriate dam safety related decisions based on advice from a consulting engineer where appropriate. The dam owner is also responsible for authorising any immediate expenditure so that urgent repair work will not be delayed.

• Undertake regular on-site monitoring and visual inspection of the conditions at the dam. The dam owner is responsible for conducting a safety evaluation of the dam and to identify any deficiency in the dam’s safety. Where deficiencies exist, the dam owner is required to take appropriate steps to minimise the potential risk of dam failure from these deficiencies.

1.4 EAP REVIEW AND APPROVAL FLOW PLAN

The EAP is reviewed annually in accordance with SOP23, prior to each wet season, to ensure contact information is up to date and all necessary parties involved in the EAP process are aware of the emergency actions required and any changes to the document.

The review of the EAP is to be undertaken in accordance with the flow path diagram shown in Figure 1.1 below to demonstrate collaboration with the appropriate disaster management groups. The process will address any revised legislative changes and the latest “Emergency Action Plan for Referable Dam Guideline”.

In order for the EAP to be effective it must demonstrate the following disaster management attributes:

• Comprehensive – An all hazards approach • Interoperable – Alignment with the disaster management system • Value for money – Link with existing systems and warning services • Scalable – Ability to ramp up as hazard events escalate to emergency events • Adaptable- Flexibility to address the circumstances of the event

This plan effectiveness will be assessed through the testing of its ability to show the above attributes are being met and if there are improvements required it can be addressed in future annual reviews


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Notes: 1 – LDMG: and DDMG 2 – DNRM&E: Department of Natural Resources, Mines & Energy 3‐ QFES: QLD Fire and Emergency Service

Review Gordonbrook Dam EAP

Consult changes and updates to EAP to SBRC, LDMG & DDC

Review and provide advice to SBRC

Revise EAP as required following consultation process & submit to LDMG & DDMG for

Review

LDMG & DDMG to review EAP and

provide assessment notice

Revise EAP after groups review and prepare response to be included with EAP

submission

Submit EAP to Chief Executive, DNRM&E2 for approval, incl assessment notice

Chief Executive DNRM&E2 assess EAP

Chief Executive DNRM&E2

gives notice to SBRC

Distribute approved EAP to relevant parties

Approved No Yes Chief Executive

DNRM&E2 gives approval notice

to dam owner.

Provide approved copy of Gordonbrook Dam EAP to:

1. Chief Executive 2 2. QFES3 3. Updates EAP Register 4. Publishes EAP on website Figure 1.1: EAP Development and Approval Flow Plan

Dam Owne

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1.5 EAP ACTIVATION LEVELS

The four levels of EAP activation are:

• Alert A heightened level of vigilance due to the possibility of a dam hazard event or an emergency event occurring. No further action may be required; however, the situation should be monitored by someone capable of assessing the potential of the threat. • Lean Forward An operational state characterised by a heightened level of situational awareness of an impending event and a state of operational readiness • Stand Up The operational state where resources are mobilised, personnel are activated, and operational activities commenced. • Stand Down Transition from responding to an event back to normal core business and/or continuance of recovery operations. There is no longer a requirement to respond to the event and the threat is no longer present. The movement through these levels of activation is not necessarily sequential. It should be applied with flexibility and adaptability and be tailored to the location and event.

Triggering one (1) of these levels of activation may not necessarily mean a similar activation of LDMP as this will depend on the hazard event type and the likelihood of an emergency event being realised.

1.6 NOTIFICATIONS

1.6.1 Notification Responsibilities The responsibilities for notifying others of a potential emergency situation for both flood and non-flood related incidences are shown in the Table 1.1 - Order of Contact. Contact Details including phone numbers, email and addresses are provided in Appendix F. Verification of emergency contact numbers shall be updated in accordance with SOP02 and the communication protocol during emergency events shall be in accordance with SOP04.


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Table 1.1 Order of Contact

Nominated Person Order of Contact

Alternate (primary contact not available) Mandatory As Required by Situation

Treatment Plant Operator Program Coordinator Manager Water and Wastewater Principal Engineer Water and Wastewater

Program Coordinator Principal Engineer Water and Wastewater) Manager Water and Wastewater

Manager Water and Wastewater

Principal Engineer Water and Wastewater


General Manager of Infrastructure (GM-I)

SBRC Local Disaster Coordinator (LDC)



PARs for dam hazard event

SBRC Deputy Local Disaster Coordinator (LDC)

Dam Incident Management Team Director of Dam Safety DNRME Brisbane

Dam Safety Consultant

CEO (SBRC)

Mayor (SBRC)


District Disaster Coordinator (DDC)

PARS (SEWS) Police (QPS)

Deputy District Disaster Coordinator (DDC)

State Emergency Service (SES)

QLD Fire & Emergency Services

QLD Ambulance Service

Local Media


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1.6.2 Communications Plan Figure 1.2 below provides the communication plan for alert levels and EAP activation.

Communication Plan

SWL > 391 AHD

or Non‐Flood Related Emergency Events

5.1 (Flood) &

5.7‐5.8 (Non‐Flood)

STAND UP

SWL > 393 AHD or

Non‐Flood Related Emergency Events

5.3, 5.4, 5.5, 5.6, (Flood) &

5.8, 5.9, 5.10, 5.11, 5.12(Non‐Flood)

LEAN FORWARD

SWL ≥ 391.5 AHD or

Non‐Flood Related Emergency Events

5.2 (Flood) &

5.7‐5.8 (Non‐Flood)

Treatment Plant Operator

Program Coordinator

Manager W&WW

Dam Safety Regulator

Local Disaster Coordinator

EAP Communication Contacts (App. F)

Dam Incident Management

Team

Phone

Phone&Email

Email/SMS/Phone1

Proceed to Stand Up as Incident

Requires

Trigger

Alert Level

EAP

Figure 1.2: Communication Plan

Primary Notification Method/Alternate Notification Method Notes:

Principal Engineer W&WW

Phone

STAND DOWN

SWL


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1.6.2 Communication of Storage Status Dam storage information will be made available on the SBRC website www.southburnett.qld.gov.au. The information to be provides is detailed in Appendix H.4, with the main emphasis on Dam level and alert notifications.

SBRC provides a subscription service through SMS/email to advise of the spillway discharge status and include a hyperlink to the SBRC website for the specific details. As part of this service there will be education program for the downstream participants as to the status and the likely impacts to make property management decisions regarding infrastructure and access arrangements.

1.6.3 Dam Hazard Event Notification Upon activating the EAP for a dam hazard event, the notifications for contacts is to be undertaken in accordance with the EAP. Notifications of uncontrolled spillway discharge will be undertaken in accordance with SOP04.

1.6.4 Dam Emergency Event Notification Once the Dam Emergency Event has been declared and the LDMP has been activated, the notifications will be managed through the LDMG. Therefore, the Standard Emergency Warning System (SEWS) can be used for the emergency notification. Details of the notification are attached in Appendix H.2. Information retain to current alerts and notifications for the emergency events will be directed to the SBC Disaster Dashboard as per Appendix H.4

In the case of need for evacuation, the LDMG Operational Sub Plan A.5 Evacuation will refer to the QLD Police who have the legislative powers to enforce evacuation.

1.7 ROLES AND RESPONSIBILITIES

Table 1.2 - Roles and Responsibilities nominates the position / title of each officer responsible for given actions or roles under the EAP. Contact details of relevant positions or agencies are included in Appendix F – Contact List. 1.8 EAP DAM INCIDENT MANAGEMENT TEAM

The Gordonbrook Dam Incident Management Team (DIMT) is formed in preparation to address emergency actions as they arise during Dam hazard and emergency events. The formation of the DMIT is triggered in the appropriate Action Plan for each dam hazard or emergency event as indicated in sections 5.1 to 5.11. The Manager Water and Wastewater is responsible for forming the DIMT during these events. The team includes specific roles and responsibilities as per table 1.1 and 1.2. Primarily the DIMT will consist of the following people or their alternative representative if the primary roles are unavailable.

Manager Water and Wastewater Principal Engineer Water and Wastewater Program Support Officer Water and Wastewater Infrastructure Administration Support (as required by Situation)

Additional support staff will be made available from the South Burnett Regional Council Infrastructure Team as required. The DIMT is also responsible for provide timely notifications to downstream residents during potential dam hazards (dam discharges), and dam hazard events that are not considered emergency situation.


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Table 1.2 Roles and Responsibilities

Position Alternative Position Responsibilities

Treatment Plant Operator Relief Operator • Visual observations of events and incidents and report • Contact Program Coordinator • Unlock gates to ensure ready access to SBRC staff

Program Coordinator Principal Engineer (W&WW)

• Contact the Principal Engineer (W&WW) • Visual assessment and inspection of dam infrastructure

as soon as safe access is possible • Lead the site team

Principal Engineer (W&WW)


• Monitor and record situation • Prepare periodic status reports for Manager Water and

Wastewater and General Manager- Infrastructure • Prepare and submit EAP event/incident reports


General Manager- Infrastructure

• Monitor and evaluate emergency situation • Notify Dam Safety Regulator as required and provide

reports • Recommendation of EAP activation to IMT • Report as necessary to General Manager –

Infrastructure • Prepare EER and submit to Dam Safety Regulator • Keep Mayor and CEO informed of emergency situation. • Liaise through LDC to LDMG

Local Disaster Coordinator

Deputy Local Disaster Coordinator

• Assess impacts of Dam Emergency Event on an ongoing basis

• Keep Chair of LDMG informed of impacts • Liaise with DDC • Activate the LDMP when the Dam Emergency Event

occurs • Provide warnings in accordance with the LDMP

EAP Dam Incident Management Team

Local Disaster Management Group

• Assess impacts of emergency on an ongoing basis • Assess the recommendations on EAP activation • Make decisions on activation of the EAP • Determine the transition from a Dam Hazard Event to a

Dam Emergency Event • Communicate to LDCC and LDMG on EAP activation


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2 DAM DETAILS 2.1 GENERAL INFORMATION ABOUT GORDONBROOK DAM

Table 2.1: General Information and Dam Parameters

Parameter Value

GENERAL

Owner of dam South Burnett Regional Council Property description Latitude 26 26’ 07” S; Longitude 15144’03” E

Lot 467/FY838992, Kingaroy, Queensland. Additional lots inundated by reservoir depending on levels.

Construction completed Original construction 1942. Second stage including raising embankment, lengthening and raising of existing spillway and construction of concrete ogee crest spillway and training walls, 1987.

Licence or development permit number --- Date of last Failure Impact Assessment June 2008 Name of water course Stuart River (AMTD 83 km) Catchment area 590 km2 Storage Capacity 6,800 ML Surface Area of Storage 130 Ha Access description Access via private gravel road that leads off from the Memerambi-

Gordonbrook Road, 10 km west of Bunya Highway. Refer Map Appendix A.

Failure Impact Rating Category 1 Population at Risk (PAR) 6 (based on AFC Report 2013) Date Assessment Accepted April 2002 Incremental Flood Hazard Category (IFHC) High C (AFC Report 2008)

Sunny Day Failure Consequence Category Significant

Required Acceptable Flood Capacity (AFC) 1:10,000 AEP Flood (AFC Report 2013)

Current Flood Discharge Capacity 72% of AFC (AFC Report 2013) Timing of Minimum Spillway Upgrades 1 October 2025 (Tranche 3- Spillway Upgrades)

Parameter Value

DESCRIPTION OF MAIN DAM EMBANKMENT

Type Compacted earth fill with downstream filter drain and grass cover and upstream dry pitched stone protection

Maximum Height 19.2m to embankment crest

Total Crest length Approx. 400m


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Parameter Value

Width at Crest 5.8m

Crest level RL 391.5 m AHD

Crest level RL 398.2 (AHD)

Parameter Value

SPILLWAY

Type Uncontrolled ogee mass concrete weir

Total Length 80.0 m

Width at Crest Level 6.3m (Mass concrete weir width)

Maximum Spillway Discharge Capacity 1950 m3/s @ ARL 397.2 m AHD

Crest level RL 391.5 m AHD Value Parameter Value

DIVERSION CONDUITS

Under Embankment Permanently Closed and Non-Operational

Diameter 1100 mm diameter concrete encased MS tunnel

Length Approx. 70 m

Pipe Type 150mm CI Pipe with 2 x sluice valves

Under Spillway

Diameter 300 mm diameter pipe with 1 x sluice valve

Length Approx. 6.5m

Pipe Type Steel

Parameter Value

OUTLET WORKS TO TREATMENT PLANT

Type Concrete tower with 2 x pumps

Parameter Value

INSTRUMENTATION

Piezometers 5 No. standpipe piezometers

Seepage measurement One V Notch Weir and 3 un-gauged filter drainage outlets

Reservoir storage level gauge Hydrostatic pressure gauge linked to Telemetry/SCADA to Kingaroy


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2.2 SPILLWAY ADEQUACY

The Spillway Adequacy Assessment Report states that the expected Dam Crest Flood (DCF) is the 1:5,000-year AEP flood; with an outflow of 2,542 m3/s. The Acceptable Flood Capacity is 3,239 m3/s which would overtop the dam embankment at RL398.2.

The report also states that according to AFC Guidelines the spillway will need to be modified to accommodate 75% of the AFC by October 2025. Modification of procedures and trigger levels will be required subsequent to any spillway augmentation works which are undertaken in the future.

2.3 POPULATION AT RISK Spillway Adequacy Assessment Report prepared by Worley Parsons in July 2008 has identified the Population at Risk, which are as follows:

Population at Risk Number

Houses at risk from DCF without Dam Break 6

Additional No. of houses which may be at risk from DCF with Dam Break 2

Total houses potentially at risk from DCF (with Dam Break) 8

Houses at risk from PMF without Dam Break 11

Additional No. of houses which may be at risk from PMF with Dam Break 1

Total houses potentially at risk from PMF (with Dam Break) 12

No. of houses at risk from Sunny Day Failure 1


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2.4 GENERAL DAM ARRANGEMENT

Figure 2.1 – General Arrangement Gordonbrook Dam


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2.5 DAM INSPECTIONS AND MONITORING

In order to maintain the embankment in a safe condition and detect any emergency conditions as it becomes apparent, the following is applicable to Gordonbrook Dam.

2.5.1 Inspections The following Inspections are carried out as per Gordonbrook Dam Operations and Maintenance Manual: Routine Visual Inspections: Conducted routinely (typically on a bi-monthly basis), and after every flood event. (SOP25) Comprehensive Inspection: Conducted 5 -Yearly. (SOP26) Safety Review: Conducted every 20 years

2.5.2 Instrumentation and Monitoring Gordonbrook Dam has a level sensor located on the raw water intake tower that measures the current storage level relative to the spillway FSL (391.5m AHD). This data is relayed back to the Water and Wastewater Department via the radio telemetry SCADA system. The raw water intake tower also has a manual site gauge with 100mm increments.

The radio telemetry system relays the dam water level data back to the main SCADA CMF and RMF servers in Kingaroy, and forwards SMS alarms to the Principal Engineer Water and Wastewater and Program Coordinator as levels rise. Alarm set points are specific to the EAP 5.2-5.6 trigger levels. All radio telemetry systems have battery backup for 6 hours, with the main CMF and RMF SCADA servers having UPS and generator back up system in place.

Gordonbrook Dam also has a remote CCTV camera located on the spillway, with a weather station to provide live coverage and weather data during flood events. This system can be accessed remotely via the Telstra 3G network, although 3G signal strength can vary and temporarily drop out of range.

In addition to the above monitoring system for flood events, Gordonbrook Dam also has five (5) piezometers installed on the dam wall and toe of the dam to allow assessment of water pressure and seepage through the dam wall. These are read every two (2) weeks and assessed by the Principal Engineer Water and Wastewater monthly. SBRC has setup survey points to assess settlement and movement of the dam wall and appurtenances. These are surveyed annually in accordance with the Gordonbrook Dam’s Operation and Maintenance Manual.

2.5.3 Backup Monitoring. Although Gordonbrook Dam has specific remote monitoring instrumentation, SBRC does not consider these devices to be 100% reliable. As such, Gordonbrook Dam EAP has been developed to ensure onsite monitoring by staff is undertaken during flood and non-flood emergency events as they become apparent.

During “Alert” and “Learn Forward” notifications, operational staff will be onsite as part of treatment operations during the day, and will confirm level data and provide visual observations whilst onsite during daily operations. During “Stand Up” notifications, operational staff are posted to the dam during the flood or non-flood event to ensure onsite monitoring is available should the remote systems fail as required necessary under SOP24


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3 DOCUMENTATION AND REPORTING 3.1 INCIDENT LOG

An Incident Log (refer Appendix E) shall be maintained on site by the Principal Engineer Water and Wastewater. Activities and decisions undertaken during any incident shall be recorded in chronological order in the Incident Log. The Incident Log shall contain the following information as a minimum:

• A description of the incident / event • Time and date of the incident / event • Time and date of all actions • Regular recordings of water level • Regular recordings of rainfall • Instrumentation recordings • Description of observed damage • Photographs and sketches of observed damage

• Details of communication which took place during the emergency

• Any further comments considered necessary.

Incident Logs (refer Appendix E) shall be supported by other relevant documentation and photographs. Comments regarding the adequacy of the EAP and any recommended changes to the EAP should be included. 3.2 REPORTING

Details of the incident / event and all actions taken shall be documented and reported to relevant SBRC staff and to the Dam Safety Regulator.

The Manager of Water and Wastewater is responsible for notification of an EAP event and submission of the Emergency Event Report (EER) to the Dam Safety Regulator within thirty (30) days following closure of the incident.


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4 EMERGENCY EVENTS AND ACTIONS 4.1 EVENT ACTIVATION LEVELS

Table 4.1 – Activation Levels for a flood event provides an overview of the activation levels for each of the potential dam hazard events that may result in a dam emergency event. The associated general actions and notifications that may be required are also included.

Table 4.1 Flood Activation Levels Activation

Levels Potential Dam Hazard /

Emergency Events General Actions and Notifications ALERT Significant rainfall in catchment predicted

storage levels rising rapidly and a possible higher volumes of spillway discharge expected. The LDMP is likely to have been activated for a Flood Hazard Event Dam Hazard Event extremely likely and a possibly resulting in a Dam Emergency Event

• Undertake visual inspection of dam and recording of water level of the storage. If possible, also monitor rainfall activity on the BOM radar and the inflows to the dam (Weens Bridge).

• Dam inspection and recording of water level at regular intervals. • Advice Notification (refer to Appendix F contact list and priority) . The

intent of the message is to advise PAR that there is no immediate danger however, they should keep themselves up-to-date with developments.

• Assessment on whether Dam Hazard Event will transition to a Dam Emergency Event and activation of LDMP required.

LEAN FORWARD

Spillway flows occurring and beginning to cause bank erosion but as yet are unlikely to impact on downstream PAR and infrastructure. Rain event predictions. Dam Hazard Event occurring and high probability of a Dam Emergency Event occurring

• Continue dam inspections, monitoring and recording of water level of the storage at regular intervals.

• Preliminary Warning: Watch and Act: Update notification (refer to Appendix F contact list and priority) to

those who received previous notifications plus notifications to Dam Safety Regulator.

The message should convey that it is likely that they will be impacted by the emergency event. That they may be in danger and should start taking action to protect their life and that of their family

Updates should be scheduled for example, to be provided every four (4) hours, but may need to be more frequent when deemed appropriate.

Advise the Dam Safety Regulator of EAP status STAND-UP 1. Spillway discharge increasing with flows that

are likely to impact on downstream PAR and infrastructure.

2. Spillway discharge is at a level that the downstream banks may be overtopped and cause impact to PAR and infrastructure

3. If flood activity continues a dam failure may occur due to overtopping.

4. Dam failure is initiated. Dam Emergency Event is occurring

• Continue dam inspections, monitoring and recording of water level of the dam if safe to do so.

• Dam inspections and more frequent recording of storage level. • Evacuate to high ground to avoid any impending flood / dam failure flows. • More frequent notifications to all relevant entities including LDMG and

council. Updates to be provided at least every few hours but also when ‘benchmark’ storage levels or discharge are being reached such as: discharges likely to close critical roads and other infrastructure record flood levels are occurring in the dam dam crest is being reached or is being overtopped.

• Immediately notify LDMG when the dam failure initiates • Take immediate notification action (refer to Appendix F contact list and

priority) to other relevant entities. • Emergency Warning: LDMG and watch desk to issue emergency warning under the EA

polygon • Advise the Dam Safety Regulator of dam failure as soon as reasonably

possible after those who are likely to be affected are notified. STAND-DOWN

Flood levels receding with storage levels dropping back towards FSL and dam releases are unlikely to further impact on PAR .

• Issue Advice Notification to previously notified entities and PAR advising the end of the emergency event

• Prepare EER and submit to the Dam Safety Regulator within 30 business days after the end of the emergency event.


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4.1.1 DAM HAZARD TRIGGER AND ACTIVATION LEVELS

The Dam Hazard Event for a flood event occurs as a result of the extent of the impact of the flood to downstream population. Storage levels in a flood event has been adopted as the trigger level for the dam hazard. The spillway discharge as a result of the storage level combined with the severity of the flood inflow could result in a dam hazard event or dam emergency event. A specific ‘Activation Reference Number’ has been allocated in this EAP to link each of the event triggers and activations to the actions of each of the responsible persons as detailed in the EAP.

It should be noted that under normal operating circumstances these specific storage levels may or may not result in Dam Hazard Event or a Dam Emergency Event. The critical assessment of the transition to either a Dam Hazard Event or a Dam Emergency Event will heavily rely on the rainfall and flood flow predictions.

Table 4.2 – Storage Trigger Levels and Activation Levels have been identified from review of the following reports:

• Spillway Adequacy Assessment Report • Comprehensive Dam Safety Inspection Report • Dam Failure Impact Assessment

Table 4.2 Storage Trigger Levels and Activation Levels

Hazard/Trigger Description Activation Reference

No.

Activation Level

Storage level is at RL 392.0 m (0.5m above spillway crest level). Substantial inflows resulting in high rate of storage level rise and further heavy rainfall is forecast and spillway discharge expected. The LDMP has likely been activated at Alert (Dam Hazard Event)

5.1 Alert

Storage level is at RL 392.4m (0.9m above spillway crest level). Substantial inflows resulting in high rate of storage level rise and continuing heavy rain is forecast but as yet are unlikely to impact on downstream PAR and infrastructure. (Dam Hazard Event and potential Dam Emergency Event)

5.2 Lean Forward

Storage level is at RL 393.0m (1.5m above spillway crest level) and continuing heavy rain is forecast. Spillway discharge increasing with flows that are likely to impact on downstream PAR and infrastructure (Dam Hazard Event or Dam Emergency Event)

5.3 Stand Up 1

Storage level is at RL 394.0m (2.5m above spillway crest level) and further rain is forecast (one of the highest recorded floods 2011) (Dam Emergency Event)

5.4 Stand Up 2

Storage Level is at RL 396.7m (1.5m below Dam Crest Level) and further rain is forecast. (Dam Emergency Event) 5.5 Stand Up 3

Storage Level rises above RL 397.7 (0.5m below dam crest level) and overtopping is imminent. (Dam Emergency Event) 5.6 Stand Up 4

Storage Level dropping towards spillway level RL391.5. No further rainfall is forecast, inflows and storage level has stabilised and no further risk of impact to PAR or infrastructure.

5.7 Stand Down


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4.2 NON-FLOOD RELATED HAZARD EVENTS

The following non-flood related events have been identified where emergency action will be necessary. Table 4.3 Non-Flood Related Trigger Events

Hazard/Trigger Description Activation Reference Number

Increase in seepage or new area of seepage 5.8

Anomalies in piezometer readings 5.9

Earthquake reported in the vicinity of the dam 5.10

Movement of dam embankment 5.11

Damage to dam embankment 5.12


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5 DAM HAZARD & EMERGENCY EVENT ACTIONS 5.1 STORAGE LEVEL IS AT RL 392.0 (+0.5M ABOVE SPILLWAY CREST LEVEL)

ALERT

During a rainfall event that has been assessed by BoM with the probability of significant rainfall that may cause inflows that would increase the storage beyond RL 392.0m, increasing discharges over the crest of the spillway >50 m3/s then consideration is to be given to Alert Condition Level.

TREATMENT PLANT OPERATOR

PROGRAM COORDINATOR

PRINCIPAL ENGINEER WATER & WASTEWATER

MANAGER WATER & WASTEWATER

LOCAL DISASTER COORDINATOR

EMERGENCY CONDITION LEVEL - DAM HAZARD EVENT - ALERT

• Notify the Program Coordinator of storage water level

• Inspect spillway. • Fill out Incident Log

and Dam Log book and continue to fill out log book until incident is closed by Manager (W&WW)

• Notify the Principal Engineer (W&WW) of storage water level

• Monitor the Telemetry outputs and check accuracy against manual readings

• Ensure that the spillway is clear of debris

• Review weather forecast through BoM website.

• Continue to monitor rainfall, forecast and inflows

• If forecast and inflows unfavourable advise Manager WWW to consider activation of EAP

• If storage level progressing rapidly toward RL392.4m (+0.9m),and the possibility of a Dam Emergency Event proceed with EAP 5.2

• When storage level


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5.2 STORAGE LEVEL IS AT RL 392.4 (+0.9M ABOVE SPILLWAY CREST LEVEL)

LEAN FORWARD If conditions in EAP 5.1 suggest that the storage level will exceed RL 392.4 (+0.9M) then proceed to LEAN FORWARD status.

TREATMENT PLANT OPERATOR

PROGRAM COORDINATOR

PRINCIPAL ENGINEER WATER&WASTEWATER

MANAGER WATER & WASTEWATER

LOCAL DISASTER COORDINATOR

EMERGENCY CONDITION LEVEL – DAM HAZARD EVENT - LEAN FORWARD

• Continue to monitor spillway and take manual readings of the storage level and report

• Continue to fill out Incident Log and Dam Log book continue to fill out log book until incident is closed by Manager (W&WW)

• Ensure appropriate Staff will be onsite for operation and monitoring purposes

• Continue to monitor the Telemetry outputs and check accuracy against manual readings

• Monitor and report on the rate of storage level increase

• Continue to monitor rainfall and inflows into Dam.

• If Dam Level is > RL393.0m AHD and increasing further above this level to become a Dam Emergency Event recommend to proceed to Stand Up 1 (EAP 5.3)

• Notify Dam Safety Regulator that EAP is activated and status is Learn Forward

• Notify the LDC of the EAP Status

• Activate the LDMP if a Dam Emergency is most likely otherwise watch and action as necessary

• If LDMP activated implement the LDMP as per the LEAN FORWARD phase requirements

• If Dam Level


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5.3 STORAGE LEVEL IS AT RL 393.0m (1.5M ABOVE SPILLWAY CREST LEVEL)

STAND UP 1

The downstream flows from the spillway level of 1.5m is likely to cause localised flooding and road closures.

PRINCIPAL ENGINEER (W & WW) MANAGER

WATER AND WASTEWATER LOCAL DISASTER

COORDINATOR

EMERGENCY CONDITION LEVEL - DAM HAZARD EVENT - STAND UP 1

• Notify the Manager Water and Wastewater of storage water level. Liaise with Manager during the course of the emergency event.

• Using the latest rates of rise, calculate the time the water level will reach RL 394.0m (+2.5m above spillway) and advise Manager Water and Wastewater.

• Continue communications with Program Coordinator and/or Treatment Plant Operators for monitoring dam level and rate of change in level on an hourly basis. (Or as necessary depending on the fill rate).

• Organise routine visual inspection as per Operations and Maintenance Manual SOP 18 when safe to do so and report any incidents to Manager Water and Wastewater. If Dam is inaccessible, instruct Treatment Plant Operators to conduct routine visual inspection and report

• If any incidents observed, proceed with EAP 5.12

• Advise the Dam Safety Regulator that current EAP status has moved to Stand Up 1 and of the emerging situation.

• Assess the downstream impacts for notifications in accordance with Appendix F

• DIMT to assess the status and the predictions of the storage discharge downstream impacts

• Notify PARs located downstream of the Dam that the EAP has been activated. Localised flooding and road closures are expected.

• If Dam Level RL393.0m AHD and processing further above this level to become a Dam Emergency Event proceed to recommend Stand Up 2 (EAP 5.4)

• Activate the LDMP if a Dam Emergency is most likely otherwise watch and action as necessary

• If LDMP activated implement the LDMP as per the STAND UP phase requirements

G for Hazard Inundation Maps, in particular G1 – Gordonbrook Dam Storage Submerged Area; and G2 – Stuart River Hazard Inundation Zone Discharging 1.5m above Full Supply Level.


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5.4 STORAGE LEVEL IS AT RL 394.0 (2.5M ABOVE SPILLWAY CREST LEVEL) AND FURTHER RAIN IS FORECAST

STAND UP 2 Gordonbrook Dam (and WTP) will be inaccessible due to road closures when dam level is at this height and above.


WATER AND WASTEWATER LOCAL DISASTER COORDINATOR

EMERGENCY CONDITION LEVEL - DAM EMERGENCY EVENT - STAND UP 2

• Notify the Manager Water and Wastewater of storage water level. Liaise with Manager during the course of the emergency.

• Establish communication with Program Coordinator and Treatment Plant Operator and confirm level.

• Ascertain forecast rainfall and river flows from Bureau of Meteorology (BoM)

• Using the latest rates of rise, calculate the time the water level will reach RL 396.7m (1.5m below Design Dam Crest Level) and advise Manager Water and Wastewater.

• Instruct Program Coordinator to undertake routine visual inspection as per Operations and Maintenance Manual SOP 18 when safe to do so and report. Report any incidents Manager Water and Wastewater.

• If any incidents observed, proceed with EAP 5.12

• Continue communications with Program Coordinator and/or Treatment Plant Operators for monitoring dam level and rate of change in level on an hourly basis.

• DIMT to assess the status and the predictions of the storage discharge downstream impacts.

• Advise the Local Disaster Coordinator (LDC) of flooding and road closures that are expected.

• DIMT to recommend to LDMG to notify PARs of Dam emergency event.


• If Dam Level 394.0m AHD, proceed with EAP 5.5 Stand Up 3

• Notify Local Disaster Management Group (LDMG) contacts.

• Chair LDMG to provide community update of the status of the emergency event.

• Advise Police and Emergency Services of the situation and the localised flooding and road closure impacts.

• Send Emergency Alert notices to via SEWS.

Refer to Appendix G for Hazard Inundation Maps, in particular G1 – Gordonbrook Dam Storage Submerged Area; and G2 – Stuart River Hazard Flood Extent Discharging 2.5m above Full Supply Level.


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5.5 STORAGE LEVEL IS AT RL 396.7m (1.5M BELOW DAM CREST LEVEL) AND FURTHER RAIN IS FORECAST STAND UP 3

Gordonbrook Dam (and WTP) will be inaccessible due to road closures when dam level is at this height.



COORDINATOR


• Inform the Manager Water and Wastewater immediately. Liaise with Manager during the course of the emergency.

• Using the latest rates of rise, calculate the time the water level will reach RL 398.2m (Design Dam Crest Level) and advise Manager Water and Wastewater.

• Continue communications with Coordinator and/or Treatment Plant Operators for monitoring dam level and rate of change in level on an hourly basis.

• Instruct Program Coordinator to immediately undertake inspection of those parts of the dam and spillway which are visible and accessible and report. During the inspection, note rainfall, water level, signs of slumps, erosion, springs, cracks or any deformation which could be classified as damage to the dam.

• Photograph and record. • Note and report any anomalies to the

Manager Water and Wastewater.

• Advise the General Manager - Infrastructure (GMI)/ Local Disaster Coordinator (LDC) with the status of the incident


• Advise the Local Disaster Coordinator (LDC) and the possible need to evacuation of PARs.

• If Dam Level 396.7m AHD, proceed with Stand Up 5 EAP 5.

• Local Disaster Coordinator (LDC) to organise notification of situation.

• Chair of Local Disaster Management Group (LDMG) to release the community notification

• LDC to liaise with DDC on situation.

• Contact and notify all residents located within the inundation through SEWS of the need to evacuate

• Advise Police and Emergency Services of the situation and the need for evacuation of the PARs under immediate threat

WHEN WATER LEVEL REACHES RL 397.2m

• Relay water levels back to Manager Water & Waste Water

• Inform LDC that the storage is approaching but still 1.0m below the dam crest level and the possible need for further evacuation of downstream residents.

• Request LDC to close roads as necessary. Consider alternative access for PARs. Potential road closures listed in Appendix G.

• SES and Police to be advised to evacuate all downstream PARs.

WHEN DAMAGE IS OBSERVED

• Advise the Manager Water & Waste Water (4) and Proceed with EAP 5.12. to EAP 5.8.

• Proceed with EAP 5.12.

• Evacuation of all PARs downstream of the dam. Minimum 3 hours’ notice required for evacuations


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IF WATER LEVEL RISES ABOVE RL 397.7m • Proceed with EAP 5.6

• Contact LDC, and recommend evacuation of all PARs downstream of the dam.

• Evacuation of all PARs downstream of the dam. Minimum 3 hours’ notice required for evacuations

WATER LEVEL LOWERS TO


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5.6 STORAGE LEVEL RISES ABOVE RL 397.7m (0.5M BELOW DAM CREST LEVEL) AND OVERTOPPING IS IMMINENT

STAND UP 4 Gordonbrook Dam (and WTP) will be inaccessible due to road closures when dam level is at this height.

PRINCIAPL ENGINEER (W & WW) MANAGER


COORDINATOR


• Inform the Manager Water and Wastewater immediately. Liaise with Manager during the course of the emergency.

• Instruct Program Coordinator to assign two staff members to remain at the dam site to monitor the water level and status of the dam

• Each member is to be accounted for and allocated a safe position upstream of the main dam embankment

• Advise LDC of storage level and the possibility of overtopping of the dam embankment.

• Advise the Dam Safety Regulator that current EAP status has moved to Stand Up 4, of the storage level and the possibility of overtopping of the dam embankment.

• Check progress of evacuations with LDC.

• LDC to proceed in accordance with the LDMP activation

• LDC to brief the Chair LDMG

• Evacuate all but two operational staff from the vicinity of the dam.

• Ensure communication to Manager of Water and Wastewater.

• Using the latest rates of water level rise, calculate the time to dam overtopping level (RL 398.2m).

• Continue to brief the Incident Management Team of situation.

• If requested, arrange preparation of media briefing for the Chair LDMG in conjunction with LDC

.

• Continue to monitor water level and rates of change in level hourly, but do not venture onto the main dam embankment.

• Note readings and report in Incident Log. • Arrange photographs to be forwarded if

possible. • Note and report any anomalies or

damage to the Manager Water and Waste Water

When Dam Level reduces to


June 2020 Page | 25

WATER LEVEL LOWERS TO


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5.7 STORAGE LEVELS DROPPING AND NO FURTHER RAIN PREDICTED

STAND DOWN Advice from BoM indicates the rain fall event risk is reduced and the inflows have stabilised such that the spillway discharge is reducing. When the storage level drops to a level that the spillway discharge has reduced to a rate that the flood level recedes to no longer impact to PARs and significant infrastructure then the Emergency Condition Level can be moved to Stand Down. In other cases where the incident did not result in moving to the next level such as Lean Forward and Stand up and ere the spillway discharge was unlikely to impact on PARs and significant infrastructure Stand Down condition level shall be activated.



COORDINATOR

EMERGENCY CONDITION LEVEL – STAND DOWN

• Continue communications with Program Coordinator and/or Treatment Plant Operators for monitoring dam level and rate of change in level on an hourly basis.

• When storage level drops


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5.8 INCREASE IN SEEPAGE OR NEW AREA OF SEEPAGE IS OBSERVED IN THE DOWNSTREAM EMBANKMENT BATTER OR SPILLWAY DRAIN

Activate EAP

TREATMENT PLANT OPERATOR PROGRAM COORDINATOR PRINCIPAL ENGINEER (W & WW)


• Investigate toe of Dam when routinely measuring and recording piezometers levels.

• If any new or unusable seepage is identified during routine investigations, photograph flow of water and record.

• Report unusual flows to Program Coordinator

• Undertake inspection of unusual flows or seepage reported by operators

• Fill out Incident Log and Dam Log and report to Principal Engineer Water and Wastewater

• Report incidents identified by Program Coordinator to Manager Water and Wastewater.

• Report any unusual seepage identified during routine inspections


WATER AND WASTEWATER

EMERGENCY CONDITION LEVEL - DAM HAZARD EVENT - LEAN FORWARD

• Notify the Manager Water and Wastewater of any noticeable increase or changes in seepage (seepage rate or colour) or surface slumping on any dam embankment.

• Liaise with Manager Water and Wastewater throughout the emergency.

• Declare an EAP Dam Hazard Event • Assemble and activate DIMT • Inform the LDC of situation

• Monitor the situation by measuring the rate of seepage flow and observe the clarity of the seepage flow. Keep notes and photographs for the Incident Log.

• Complete the Incident Log.

• Engage and brief the Dam Safety Consultant to undertake a Special Dam Safety Inspection (Procedure to be supplied) within 72 hours of the Incident.

• Advise the Dam Safety Regulator that the EAP has been activated and of the general situation.

EMERGENCY CONDITION LEVEL - DAM EMERGECNY EVENT - STAND UP

IF TURBID SEEPAGE IS NOTED OR SIGNIFICANT INCREASE IN SEEPAGE • Advise the Manager and proceed with EAP 5.12.

• Advise the General Manager – Infrastructure and Dam Safety Regulator of the EAP status

• Proceed with EAP 5.12.


AFTER THE EVENT • Subject to the Dam Safety Consultant advice • Complete the Incident Log and Report. • Submit Incident Log to Manager Water & Waste Water.

• Review and complete the Incident Log. • When Manager Water and Wastewater, is satisfied that

incident is resolved; stand down incident team and issue final notification advising of incident closure.

• Submit EER to Dam Safety Regulator within 30 days of incident.

Refer to Appendix G for Hazard Inundation Maps, in particular G3 –Stuart River Hazard Inundation Zone Sunny Day Failure Dam Break Flood Extent.


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5.9 ANOMALIES IN PIEZOMETER READINGS

Activate EAP




• Notify the Manager Water and Wastewater of any noticeable increase or changes in piezometer readings.

• Undertaken Inspection of Dam wall for any unusual changes.

• Review results

EMERGENCY CONDITION LEVEL –DAM HAZARD EVENT- LEAN FORWARD

• Report unusual flows to Manager Water and Wastewater. • Review results • Activate DIMT if report indicates possible high risk of

damage EMERGENCY CONDITION LEVEL –DAM EMERGENCY EVENT - STAND UP

IF RESULTS INDICATE POTENTIAL INSTABILITY OR FAILURE • Immediately perform a Routine Dam Safety Inspection (as

per Operations and Maintenance Manual SOP 18). During the inspection, note signs of slumps, erosion, springs/seepage, cracks, or deformation which could be classified as damage to the dam.

• On receipt of the inspection report, proceed with EAP. 5.11

WHEN DAMAGE TO THE DAM IS OBSERVED • Advise the General Manager - Infrastructure and proceed

with EAP 5.12 • Liaise with Manager Water and Wastewater throughout the

process.

• On receipt of the damage report, proceed with EAP. 5.12


AFTER THE EVENT • Subject to the outcome of the investigation • Complete the Incident Log and Report. • Submit Incident Log to Manager Water & Waste Water.


incident is resolved, stand down incident team and issue final notification advising of incident closure.



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5.10 EARTHQUAKE IS REPORTED IN THE VICINITY OF THE DAM

Activate EAP

PRINCIPAL ENGINEER (W & WW) MANAGER WATER AND WASTEWATER

EMERGENCY CONDITION LEVEL - DAM EMERGENCY EVENT - STAND UP

• Inform the Manager Water and Wastewater and General Manager - Infrastructure that an earthquake has been felt in the area.

• Liaise with Manager Water and Wastewater. • If possible, contact Geoscience Australia to ascertain

epicentre and magnitude of earthquake

• Activate the EAP at Stand Up • Activate DIMT. Inform the LDC of situation

• Immediately perform a Routine Dam Safety Inspection (Refer to Gordonbrook Dam O&M Manual- SOP 17). During the inspection, note signs of slumps, erosion, springs/seepage, cracks, or deformation which could be classified as damage to the dam.

• Monitor the situation, keeping notes and photographs for the Incident Log and the Routine Dam Safety Inspection.

• Brief the Dam Safety Consultant to undertake a Special Dam Safety Inspection (Refer to Gordonbrook Dam O&M Manual- SOP 24) within 72 hours of the Incident.


WHEN DAMAGE TO THE DAM IS OBSERVED • Advise the Manager Water and Wastewater Infrastructure

and proceed with EAP 5.12

• On receipt of the damage report, proceed with. EAP 5.12


AFTER THE EVENT • Subject to the DAM Safety Consultant assessment • Complete the Incident Log and submit to Manager Water &

Waste Water


incident is resolved, stand down incident team and issue final notification advising of incident closure.



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5.11 MOVEMENT OF DAM EMBANKMENT

Activate EAP

PRINCPAL ENGINEER (W & WW) MANAGER


EMERGENCY CONDITION LEVEL - DAM EMERGENCY EVENT - STAND UP

• Inform the Manager of Water and Wastewater that movement has been noticed.

• Declare a Dam Emergency Event • Inform the General Manager - Infrastructure and CEO

(SBRC) of the situation. • Activate Dam Incident Management Team (DIMT) • Liaise with LDC to inform the DDC of situation

• Immediately perform a Routine Dam Safety. During the Dam Safety Inspection (as per Operations and Maintenance Manual SOP 18), note any signs of slumps, erosion, springs, cracks or any deformation, which could be classified as damage to the dam.

• Monitor the situation, keeping notes and photographs for the Incident Log and the Routine Dam Safety Inspection (as per Operations and Maintenance Manual SOP 18).

• Engage and brief the Dam Safety Consultant to undertake a Special Dam Safety Inspection (For procedure refer to Gordonbrook Dam O&M Manual- SOP 25) within 72 hours of the Incident


•

IF MOVEMENT HAS RESULTED IN DAMAGE TO THE DAM • Advise the Manager Water and Wastewater • Log an entry in Incident Log

• On receipt of the damage report, and the recommendation is that the damage is Critical proceed with EAP 5.12

• Advise the General Manager – Infrastructure


AFTER THE EVENT • Stand Down for this event is triggered on the receipt of the

consultant’s report that the dam is not at risk of failure. • Complete the Incident Log and submit to Manager Water &

Waste Water. • Provide the Emergency Event Report to the Manger Water

and Wastewater within 14 days

• Review and sign off the Incident Log. • When satisfied that incident is resolved, stand down DIMT

and issue final notification advising of incident closure. • Advise the LDC of the Stand Down • Submit Emergency Event Report to Dam Safety

Regulator within 30 days of incident.


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5.12 DAMAGE TO DAM OR SPILLWAY (INCLUDING OBJECTS CRASHING INTO DAM AND TERRORIST INCIDENTS)

Activate EAP



EMERGENCY CONDITION - DAM EMERGECNY EVENT- LEVELSTAND UP

• If damage to any part of the dam is noticed, report it immediately to the Manager – Water and Wastewater

• If damage or potential damage is related to a terrorist threat (or possible terrorist threat), contact ‘000’ and notify Police.

• Declare a Dam Emergency Event. • Assemble DIMT). • Attend site and inspect the damage. • Inform the LDC, DDC, CEO and the Mayor of the

situation. • Assess and report the extent of damage to the Manager

Water and Wastewater. • Advise the Dam Safety Regulator that the EAP has been

activated and of the general situation. • Advise the General Manager-Infrastructure of the general

Situation and that the EAP has been activated • Engage and relay details of the damage to the Dam

Safety Consultant. Information that should be relayed includes: The type of damage; The location of damage; Water level; Weather forecast; Specific details of damage, e.g. flow and colour of

seepage, size of cracks (length, width, orientation), size of slumps, sink holes etc.

• If necessary, arrange for the Dam Safety Consultant to inspect the damage and any repairs and, if necessary, undertake a Special Dam Safety Inspection (Gordonbrook Dam O&M Manual- SOP 24).

• Monitor the situation and keep the Manager Water and Wastewater.

• Note any changes in the nature of the damage.

• Advise General Manger-Infrastructure of situation reports as they are provided

• Decide whether or not to instigate immediate repairs • If repairs are not undertaken, the damage is to remain

monitored. • If the situation is considered serious, inform Local

Disaster Management Group to evacuate affected downstream residents as per EAP 5.5 Stand Up procedure. Update LDC on likely risks involved.

• Record all relevant events in the Incident Log. • On completion of the repairs, monitor and report to the

Manager – Water and Wastewater.

• Regularly update the General Manager - Infrastructure on progress.

• Coordinate repairs on site in accordance with instruction from the General Manager - Infrastructure.

• If repairs are to be undertaken, the Dam Safety Consultant is to be consulted over the specification of the repairs. Materials and/or services may be obtained through existing SBRC suppliers or as decided otherwise by the Manager – Water and Wastewater.


June 2020 Page | 32

PRINCIPAL ENGINEER (W & WW) MANAGER WATER AND WASTEWATER


ON COMPLETION OF REPAIRS • Monitor situation and report to the Manager – Water and

Wastewater.

• Provide situation report to the General Manger

Infrastructure • If repairs appear to have stabilised the damage, confirm

with the Dam Safety Consultant and when Manager Water and Wastewater is satisfied that incident is resolved, stand down incident team and issue final notification advising of incident closure.

• The Dam Safety Consultant is to confirm the closure of any Incident associated with damage to the dam.

• The Dam Safety Consultant is to identify any required follow up repairs or works. Document these required works in the Incident Log and in the Dam Data Book.

AFTER THE EVENT • Stand Down for this event is triggered on the receipt of the

consultant’s report that the dam is not at risk of failure • Complete the Incident Log and submit to Manager Water &

Waste Water - Infrastructure.

• Review and complete Incident Log • Submit EER to Dam Safety Regulator within 30 days of

incident.


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6 EMERGENCY ACTION PLAN GENERAL INFORMATION 6.1 EAP EXERCISES & TESTING

The EAP should be tested annually by conducting an exercise of each of the potential emergency situations identified within this EAP. The exercise could be either desktop or field based with the objective to test the plan and to refresh and train new personnel with actions in the EAP. Testing of the plan should also be undertaken with the wider regional exercises of the LDMG in relation to flooding hazards.

The exercise should be debriefed in order to identify opportunities for improvement of the EAP. The information should be available for the next EAP review following the exercise.

6.2 EAP TRAINING

Training of the use and implementation of this EAP document is carried out at various times throughout the year. Specific pre-wet season training is undertaken leading up to the wet season. During this period SBRC staff complete work instructions for site preparations and from July to September carry out checks on stores; supplies of fuel; and the current EAP, such as contact details for individuals and dam information.

Dam operation training will be in accordance with SOP15. EAP training that is carried out on-site includes walkthroughs of new changes and Q&A to check the knowledge and competency of all those who attended. This on-site training is presented to relevant SBRC staff and disaster management stakeholders where necessary. Information sessions are carried out once a year with the same walkthrough of new changes and Q&A. New SBRC employees in these various roles also have a training session of the EAP as part of their induction.

Potential opportunities to train with SunWater, as it owns dams within the region and will need to undertake exercise with SBRC LDCC to test their EAPs, should be assess and considered as part of the training opportunities.

6.3 EAP EDUCATION

SBRC will use fact sheets to undertake education of the downstream property owners in order to understand the status report by SBRC, informing themselves of the likely impacts of the spillway discharge. Information will also be displayed on SBRC’s website and the Disaster Dashboard. Opportunity will be taken to jointly supply fact sheets and education material with the disaster management entities in order to uniformly deliver a consistent message. SBRC is required to ensure have PARs have an appropriate evacuation plan in the event of a dam failure. In conjunction with the above education plan the PAR will be advised of the need for their evacuation plans and SBRC will assist in the advice on closed roads associated with each of the likely scenarios for the spillway discharge and the dam failure events.


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APPENDIX A

Access to Gordonbrook Dam


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Gordonbrook Dam is accessed via a private gravel road (Treatment Plant Road) that leads off from Memerambi-Gordonbrook Road, 10 km west of the Bunya Highway. Dam location is shown in the below map.:


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APPENDIX B

Storage Capacity


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Storage capacity and discharge Flows are shown in the following charts.


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APPENDIX C

Gordonbrook Dam Catchment and Flood Hydrology


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The following information provides details of Gordonbrook Dam’s catchment and flood hydrology (design rainfall data and flood routing results) as determined from Gordonbrook Dam Spillway Adequacy Assessment 2008 (Worley Parsons).

Item Description

Figure C.1 Gordonbrook Dam Catchment

Figure C.2 Frequency Curves for Maximum Inflow and Outflow for Gordonbrook Dam

Figure C.3 Estimated peak flood storage levels for Gordonbrook Dam

Figure C.4 Gordonbrook Dam Catchment IFD Design Rainfall Intensity

Figure C.5 Gordonbrook Dam Catchment Rainfall Frequency Curve

Table C.1 General Information and Dam Parameters

Table C.2 RAFTS design Inflows and Outflows for Gordonbrook Dam for various durations

Table C.3 Storage routing results for critical storm durations.

Table C.4 Rainfall Depths and Ratio to PMP for all events

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Worley Parsons Services Pty. Ltd.ABN 61 001 279 812

PO Box 1757, Sunshine Plaza, QLD 4558Ph. (07) 5475 6400 Fax. (07) 5475 6499

GORDONBROOKDAM BREAK

FLOOD STUDY

APPENDIX 1

File Path : Z

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RAFTSSUB-CATCHMENT

BREAKDOWN

2 0 2 4 6

KilometresScale: 1:200,000

Projection T

rans. M

erc. MG

A56(G

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4)

OneWayto zero harm

TM

LEGEND

WatercourseLine

RAFTS D/S Subcatchments

RAFTS U/S Subcatchments

steve.carrollText BoxFigure C1


June 2020 Page | 43

Table C.2 RAFTS design Inflows and Outflows for Gordonbrook Dam for various durations Inflows

Outflows


June 2020 Page | 44

Figure C.2 Frequency Curves for Maximum Inflow and Outflow for Gordonbrook Dam


June 2020 Page | 45

Table C.3 Storage routing results for critical storm durations


June 2020 Page | 46

Figure C.3 Estimated peak flood storage levels for Gordonbrook Dam


June 2020 Page | 47

Table C.4 Rainfall Depths and Ratio to PMP for all events


June 2020 Page | 48

Figure C.4: Gordonbrook Dam Catchment IFD Design Rainfall Intensity


June 2020 Page | 49

Figure C.5 Gordonbrook Dam Catchment Rainfall Frequency Curve


June 2020 Page | 50

gordonbrook dam emergency action plandata.dnrm.qld.gov.au/eap/gordonbrook-eap.pdf · 2020. 7....

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