Orica Villawood HAZOP Report Rev E

HAZOP STUDY REPORT,

REMEDIATION OF THE FORMER

ORICA VILLAWOOD SITE

Prepared by: Dean Shewring

17 April 2013

Pinnacle Risk Management Pty Limited ABN 83 098 666 703

PO Box 5024 Elanora Heights

NSW Australia 2101 Telephone: (02) 9913 7284 Facsimile: (02) 9913 7930

Pinnacle Risk Management

Orica Villawood HAZOP Report Rev E.Doc 17 April 2013

Disclaimer

This report was prepared by Pinnacle Risk Management Pty Limited (Pinnacle Risk Management) as an account of work for Orica. The material in it reflects Pinnacle Risk Management’s best judgement in the light of the information available to it at the time of preparation. However, as Pinnacle Risk Management cannot control the conditions under which this report may be used, Pinnacle Risk Management will not be responsible for damages of any nature resulting from use of or reliance upon this report. Pinnacle Risk Management’s responsibility for advice given is subject to the terms of engagement with Orica.

HAZOP Study Report, Remediation of the Former

Orica Villawood Site

Rev Date Description Reviewed By

A 27/6/12 Draft for Comment Orica

B 12/8/12 Orica Comments Included Orica

C 13/8/12 Final Issue -

D 16/4/13 Supplementary and Water Treatment Plant HAZOPs Added

Orica

E 17/4/13 Final Issue -


Orica Villawood HAZOP Report Rev E.Doc 17 April 2013

CONTENTS

EXECUTIVE SUMMARY ............................................................................................ I

GLOSSARY ............................................................................................................ II

1 INTRODUCTION .............................................................................................. 1

2 PROCESS DESCRIPTION AND HAZOP SCOPE .................................................. 2

3 METHODOLOGY ............................................................................................. 2

3.1 General ............................................................................................. 2

3.2 Meeting Procedures ........................................................................ 3

4 STUDY TEAM ................................................................................................. 4

5 DISCUSSION AND CONCLUSIONS ..................................................................... 5

5.1 Analysis of Main Findings .............................................................. 5

5.2 Actions Arising from the HAZOP ................................................... 6

6 REFERENCES ................................................................................................ 7

LIST OF TABLES

Table 1 – HAZOP Team .................................................................................... 4

LIST OF APPENDICES

Appendix 1 - Approval of HAZOP Chair.

Appendix 2 - Process Description

Appendix 3 - HAZOP Drawings

Appendix 4 - HAZOP Guide Words.

Appendix 5 - HAZOP Minutes.


Orica Villawood HAZOP Report Rev E.Doc 17 April 2013 i

EXECUTIVE SUMMARY

Orica is proposing to install and operate a soil processing facility at the former Orica Villawood site. The Site contains waste byproducts of industrial activities which ceased in 2000, in particular DDT and its degradation products DDD and DDE. The contaminants will be separated from the soil and destroyed within the process.

The Minister for Planning granted development consent for the Project in May, 2012. Project Development Consent Condition 21(b) requires the preparation of a Hazard and Operability (HAZOP) Study.

Orica requested that Dean Shewring from Pinnacle Risk Management chair the HAZOP study. This report details the results of the HAZOP study in accordance with the requirements of the Department of Planning and Infrastructure’s HAZOP Guidelines.

The main participants had appropriate experience in the design and operation of soil processing (or similar) plants. Therefore, the hazards were generally well known as well as the required control measures to reduce risk to acceptable levels.

The plant design is an established design with a number of similar plants being operated throughout the world. Therefore, many of the significant potential hazardous events and operability problems were already known which reduced the demand on this study. This included incidents from recently commissioned plants for Orica and other companies.


Orica Villawood HAZOP Report Rev E.Doc 17 April 2013 ii

GLOSSARY

DoPI Department of Planning and Infrastructure

DTD Directly-heated Thermal Desorption

ECS Emission Control System

FSB Feed Soil Building

HAZOP Hazard and Operability Study

HIPAP Hazardous Industry Planning Advisory Paper

PHA Preliminary Hazard Analysis

P&ID Piping and Instrumentation Diagram

STA Soil Treatment Area

VOC Volatile Organic Compound


Orica Villawood HAZOP Report Rev E.Doc 17 April 2013 1

REPORT

1 INTRODUCTION

Orica is proposing to install and operate a soil processing facility at the former Orica Villawood site. The Site contains waste byproducts of industrial activities which ceased in 2000, in particular DDT and its degradation products DDD and DDE. The contaminants will be separated from the soil and destroyed within the process.

The Minister for Planning granted development consent for the project in May, 2012.

Development Consent Condition 21(b) specifies the following requirements for the HAZOP study.

"Prior to Site Establishment, the Proponent shall obtain the Director-General’s approval of the following study:

b) a Hazard and Operability Study (HAZOP) chaired by an independent, qualified person or team. The independent person or team shall be approved by the Director-General. The Study shall be carried out in accordance with the Department's publication Hazardous Industry Planning Advisory Paper (HIPAP) No. 8 - HAZOP Guidelines (Ref 1) and shall include consideration of measures to prevent any accidental spills of liquids and/ or liquid wastes on all relevant tanks and equipment used for the storage and handling of liquids or liquid wastes, including associated pipes and hoses.

Orica requested that Dean Shewring from Pinnacle Risk Management chair the required HAZOP study. The approval received from the Department of Planning and Infrastructure (DoPI) for the chair of this project’s HAZOP study is shown in Appendix 1.

This report details the results of the HAZOP study and is written to meet the requirements of the Department of Planning and Infrastructure’s HIPAP Number 8 and Development Consent Condition 21(b).

The HAZOP study on the main contaminant destruction process was detailed in revisions A to C of this report. Following this study, two additional HAZOPs were performed. The first additional study reviewed the air compressor for the evaporative cooler and the pugmill water system. The second additional study reviewed the waste water treatment plant. The results of these two additional studies have been added to revision D of this report.

The aim of the HAZOP study is to identify potential hazardous events and significant operability problems associated with the proposed operations. This



aim is inherent for all HAZOP studies. The scope for this study is detailed in Section 2 of this report.

2 PROCESS DESCRIPTION AND HAZOP SCOPE

A copy of the detailed process description for the soil treatment plant is supplied in Appendix 2.

In summary, the feed soil is initially heated in a dryer to remove the volatile contaminants which are then destroyed in a directly-heated thermal desorption unit. The resultant product gases are then absorbed within a scrubber. Treated soil can then be returned to the site.

In the waste water treatment plant, water from various site containments is processed via settlers, flocculation (including chemical additional and pH adjustment) and a series of filters to remove the contaminants. The purified water is discharged to sewer.

Copies of the drawings used in the study which detail the process areas are supplied in Appendix 3.

As the natural gas supply train to the directly-heated desorption unit will be compliant to the relevant Australian Standard then the HAZOP just considered deviations from the design intent associated with natural gas supply (rather than try to alter an Australian Standard compliant system).

3 METHODOLOGY

3.1 GENERAL

A HAZOP study is a hazard study which concentrates on how the design will cope with abnormal conditions, rather than on how it will perform under normal conditions. The study is comprised of a review of each unit operation, examining each for possible causes of a wide range of process abnormalities and their consequences.

HAZOP provides the opportunity for people to think creatively and examine ways in which hazards or operating problems might arise. To reduce the chance of missing something, a HAZOP is carried out in a systematic manner, using guide words to consider each pipeline and each type of hazard in turn. The study is carried out by a team so that input from all areas of functional expertise can be provided.

The results of a HAZOP depend heavily upon the experience and attitudes of the team members and on the leadership style adopted. In this study, the members of the team had good experience, knowledge and skills and had the authority to approve the actions decided upon.



3.2 MEETING PROCEDURES

The HAZOP study of each section of plant followed the procedure given below:

The process design engineer outlined the broad purpose of the section of design under study and displayed on the relevant P&ID’s on the wall. This outline included design features, operating conditions, description of fittings and details of equipment.

Any general questions about the scope and intent of the design were answered.

The first section or area of the design was highlighted for study, typically an area where material flows into the plant.

Any general questions about this area were then answered. Minutes may be generated during this discussion. If so, they have been recorded with the guide word ”General Discussion”.

The detailed "line by line" study commenced at this point. The HAZOP leader led the group through the HAZOP guide words. Each guide word is a prompt, such as "MORE OF OR HIGH FLOW", which identifies a deviation from normal operating conditions that may lead to a hazardous event or significant operability problem. This is used to prompt discussion of the possible causes and effects of flow at an undesirably high rate. If, in the opinion of the team, the safeguards for the combination of the consequences and likelihood of a credible event are inadequate then an action is recorded in the minutes.

For major risk areas the need for action is assessed quantitatively (by Hazard or Reliability Analysis). For less significant risks the need for action can be based on experience and judgement. For this study, all actions could be appropriately addressed by the nominated HAZOP team members / company.

The main aim of the meeting was to find problems needing solution, rather than the actual solution. When the group became tied down by trying to resolve a problem, the issue was minuted as requiring further review outside the meeting, and the study proceeded.

All changes agreed at the meeting were minuted with some being marked on the HAZOP master P&ID’s.

Note that all actions were recorded in the minutes as well as significant discussion points which did not result in any actions. The latter were recorded as a means to record the basis of safety for a potential hazardous event or operability problem.

The guide words used during the study are listed in Appendix 4.



All actions are listed in the HAZOP minutes, contained in Appendix 5. It is noted that safeguards are only recorded by exception. It is assumed that the procedures within the Orica safety management system will be used effectively (as discussed throughout the HAZOP study).

As the purpose of a HAZOP study is to identify, i.e. not necessarily solve, potential hazardous events and significant operability problems associated with the process under review, some of the actions require further review post the study. As a general rule, a HAZOP facilitator allows approximately 5 to 10 minutes to resolve any issues identified during the study. If a solution cannot be agreed to within this timeframe then the issue is minuted and the study proceeds.

The reason for this approach is that a positive, open, questioning mindset is required from the team members. This allows creative brainstorming to identify possible abnormal plant conditions that may lead to potential hazardous events and/or significant operability problems. Teams that become tied down trying to resolve all issues, in particular problems that require further calculations etc, lose their creativity and hence the basis for the study effectiveness is lost.

4 STUDY TEAM

The HAZOP study for the project was conducted in a number of sessions from January to November, 2012.

The main HAZOP team participants had the appropriate level of experience in design and/or operation of soil processing plants (or similar processes). Table 1 shows the team members who participated in the HAZOP study.

The meetings were led by Dean Shewring with the minutes being recorded by Peter O’Dea.

Table 1 – HAZOP Team

HAZOP Role Name Company

HAZOP Chair Dean Shewring Pinnacle Risk Management

HAZOP Secretary Peter O’Dea Orica

Project Management Peter O’Dea Lindsay Killin Cameron McLean Richard Giles

Orica EnviroPacific EnviroPacific EnviroPacific

Site Management Representative

Gwenda Lister Orica

Process Design and Plant Operation Representatives

Brett Garton Bala Kathiravelu Rudy Maes Keith Chapman Tai Truong Pearce Anderson

EnviroPacific Orica Consultant to Chapman Services Chapman Services EnviroPacific EnviroPacific



5 DISCUSSION AND CONCLUSIONS

5.1 ANALYSIS OF MAIN FINDINGS

The HAZOP team assembled for the study was well balanced in terms of disciplines and experience. The team sizes were generally kept to the required four to eight people. This increases the ability to achieve a creative brainstorming workshop to help ensure maximum effectiveness and quality.

The main participants had appropriate experience in the design and operation of soil processing (or similar) plants. Therefore, the hazards were generally well known as well as the required control measures to reduce risk to acceptable levels.

The plant design is an established design with a number of similar plants being operated throughout the world. Therefore, many of the significant potential hazardous events and operability problems were already known which reduced the demand on this study. This included incidents from recently commissioned plants for Orica and other companies.

Potential hazardous events concerning releases of harmful materials via gaseous, liquid or solid losses of containment were reviewed during the study. Assuming the proposed safeguards remain effective then the risk of such events should be low.

Any significant changes to the HAZOP design should be separately assessed for new potential hazardous events and operability problems. This is commonly achieved by utilising a management of change programme within the project and may require further review using the HAZOP technique.

During the study, industry standard operating procedures were discussed and included as potential causes for hazardous events and significant operability problems. Any significant issues identified have been recorded in the HAZOP minutes for inclusion in the final version of the standard operating procedures for the Orica facility.

HAZOP studies are, by definition, a qualitative risk assessment. The decisions made by the HAZOP team members are based on their experience and knowledge of the type of processing plant under review. If the HAZOP team members determined the existing control measures were adequate then no further action is required. Significant points of discussion (generally if significant consequential impacts are possible) were recorded even though the control measures were deemed acceptable by the HAZOP team. All issues requiring a response were included in the HAZOP minutes.



5.2 ACTIONS ARISING FROM THE HAZOP

Completed HAZOP actions need to be tracked within the project’s HAZOP action register or equivalent. Regular project meetings should include a review of the progress of closing-out all of the actions. It is normally the responsibility of the project manager to ensure that all of the HAZOP actions are completed. The HAZOP drawings and a record of the completed actions should be retained with the plant files.


Orica Villawood HAZOP Report Rev E.Doc 17 April 2013 A1.1

Appendix 1

Approval of HAZOP Chair

HAZOP Study Report, Remediation of the Former Orica

Villawood Site



Appendix 1 – Approval of HAZOP Chair.



Appendix 2

Process Description


Villawood Site



Appendix 2 – Process Description.

1. Pre-Treatment of Materials

The pre-treatment of excavated materials will be undertaken in two stages. Initially, excavated

material and overlying material may be screened within the Remediation Area compound.

Material required to be treated (in the Directly-heated Thermal Desorption (DTD) Plant) will be

transported to the Feed Soil Building (FSB), where further handling and testing of this material

will take place.

The material will be stockpiled in the FSB using a front end loader before undergoing further

screening and testing for contaminant levels and other characteristics which will be required for

the DTD treatment process. The material will then be blended to achieve a relatively

homogenous feed material prior to being loaded into the feed hopper of the DTD Plant.

Activities within the FSB, including screening and testing will take place 24 hours per day, seven

days per week.

2. Feed Soil Building and Emission Control System

The purpose of the FSB is to control emissions during pre-treatment activities and ensure these

emissions are vented to atmosphere through an Emission Control System (ECS).

The FSB will be constructed of a steel frame with metal sheeting. The building will contain an

approximate seven day working inventory of feed soil plus a sufficient buffer for soil drying and

other pre-treatment activities. This inventory volume is designed to provide adequate storage

capacity to feed the thermal treatment plant during periods when unforeseen conditions

interfere with normal excavation activities.

The FSB will be fitted with an air-lock and automated wheel wash, louvres and an ECS for air

quality control.

The FSB will be equipped with personnel entrances and truck entrances. The truck entrances

will include an air-lock consisting of a small structure internal to the enclosure. The air-lock will

be equipped with two doors. When a truck enters the air-lock, the outer door will open while the

inside door is closed. Once the truck enters the air-lock, the outer door will close, the inner door

will open and the truck will enter the enclosure. The procedure will be reversed when a truck

exits the enclosure.

An ECS will be constructed and operated to preserve air quality within the building and minimise

emissions (dust and organic vapours) to the atmosphere. The ECS will be operated to ensure

the flow of air into the FSB (i.e. air pressure within the FSB will be slightly lower than ambient air

pressure). Conceptually, the ECS will comprise an induced draft fan, duct work system,

particulate control device (dust filters) and a stack.

The air exhausted from the FSB will first pass through a particulate control device to remove

fugitive dust. Dust removed will be collected in enclosed drums or hoppers. When the dust

collection container is taken off-line, the dust will be taken to the Soil Treatment Area (STA) for

treatment.

Air will be exhausted to the atmosphere via a stack. Periodic stack testing will be undertaken in

accordance with license requirements. Permanent analysers will also be installed on the stack to

detect any unacceptable contaminant concentration levels.



3. Directly-heated Thermal Desorption Plant

The DTD Plant will be located within the STA. After pre-treatment in the FSB, the excavated

materials will be fed into the feed hopper located inside the FSB. The materials will be

transported via a conveyor to the DTD Plant for treatment.

The DTD Plant will operate 24 hours a day, seven days a week with the seventh day typically

scheduled as downtime for maintenance. The nominal maximum rate of treatment through the

DTD Plant is 15 tonnes per hour.

The DTD Plant will have a footprint of approximately 50 m by 25 m. It will be established within

a concrete paved and bunded area having its own internal surface water drainage control

measures. Electrical power to the DTD Plant will be provided by mains power, with a diesel

powered generator used as a back-up. Natural gas sourced from the mains supply, will be used

to fire the heating burners of the plant.

Brief descriptions of typical key unit operations in the process are presented below.

Rotary Dryer

The first step in the DTD treatment process involves the volatilisation or separation of

contaminants from the material in the rotary dryer.

The rotary dryer utilises natural gas as fuel to heat the contaminated material to a temperature

of approximately 350ºC to 450ºC.

In a co-current system, the contaminated material enters the rotary dryer at the end where the

burner is located and the combustion gas and treated soil move in the same direction to where

they exit at the opposite end of the dryer.

Contaminants desorb and volatilise as they pass through the dryer. Soil is heated in the first

third of the dryer with most desorption and volatilisation occurring in the next third as

contaminants reach their boiling points.

Once it has passed through the rotary dryer, the heated soil material passes to a pugmill where

it is sprayed with water for cooling and rewetting. The treated material is then transferred to

temporary treated soil stockpiles awaiting validation.

Cyclone

The off-gases flow from the rotary dryer through a cyclone, where large dust particles are

removed, to the thermal oxidiser. The dust from the cyclone is directed to the pugmill where it is

mixed with the treated soil for rewetting and validation.

Thermal Oxidiser

The thermal oxidiser is used to treat the gases produced through the heating of the soil material

in the rotary dryer and would be designed to be Stockholm compliant, i.e. with appropriate

residence time, temperature and turbulence.

The thermal oxidiser operates at a temperature of about 1,000ºC using natural gas. At this

temperature, the contaminants present in the gas (from the feed material) oxidise or decompose

forming carbon dioxide, water vapour and hydrogen chloride with small amounts of other by-

products such as chlorine and sulphur compounds.



In order to maintain the correct temperature to maximise destruction efficiency and minimise the

formation of by-products, the thermal oxidiser will be fitted with a sophisticated temperature

control system which will be consistently monitored.

Quench

Once gases have passed through the thermal oxidiser they must be rapidly cooled to minimise

the potential for dioxin formation and allow further treatment before release to the atmosphere

(as required by the Stockholm Convention).

To achieve this, the hot gases are drawn into the quench by an induced draught fan. In the

quench, water is injected to rapidly cool the gases to a temperature which is suitable for further

treatment.

Baghouse

The cooled gas from the quench is combined with steam from the pugmill and drawn into the

baghouse by an induced draught fan. The baghouse contains a series of fabric filters which

remove particulates.

Acid Gas Scrubber

The final step in the treatment process involves the removal of acid gases from the exhaust gas.

The acid gas scrubber consists of a packed tower with a re-circulating caustic solution that

reacts with any hydrogen chloride and chlorine in the exhaust gas to form a salt solution.

Following this, the ‘clean’ treated gas is vented to the atmosphere via the scrubber stack which

is some 30 m in height.

Treated Soil

Treated soil will be stockpiled adjacent to the STA with drains and bunds provided to manage

runoff. Treated materials stored in this area will undergo validation testing and reclassification.

This is to determine whether the process has been effective and whether or not the materials

are ready for reuse at the Site. Stockpiles will be stabilised with spray grass or other such

treatment and will be wetted when necessary to control dust.

The treated, stockpiled soil will be retained until completion of remediation works at the Site

when it will be transported (by truck) to the Remediation Areas for reinstatement works.



Appendix 3

HAZOP Drawings


Villawood Site



Appendix 3 – HAZOP Drawings.



Appendix 4

HAZOP Guide Words


Villawood Site



Appendix 4 – HAZOP Guide Words.

Note that the main headings are shown only. Some main headings included various sub-prompts as well.

Line-By-Line Guide Words – Continuous Fluid Systems

High Level / High Flow

Low Level / Low Flow

Zero Flow / Empty

Reverse Flow

High Pressure

- Venting, relief

Low Pressure

- Venting, relief

High Temperature

Low Temperature

Impurities

- Gaseous, liquid, solid

Change in Concentration or Composition / Two Phase Flow / Reactions

Testing

- Equipment / product

Plant Items

- Operable / maintainable

Electrical

Instruments



Overview Guide Words

Toxicity

Commissioning

Startup

Shutdown (isolation, purging)

Breakdown (including services failure)

Effluent

Fire and Explosion

Noise / Vibration

Materials of Construction

Quality and Consistency

Output - Reliability and Bottlenecks

Efficiency – Losses

Simplicity



Appendix 5

HAZOP Minutes


Villawood Site



Appendix 5 – HAZOP Minutes.

PINNACLE RISK MANAGEMENT - HAZOP RECORD SHEET

PROJECT: Orica, Villawood, DTD Project TEAM MEMBERS: Bala Kathiravelu, Gwenda Lister, Keith Chapman, Rudy Maes, Cameron McLean, Lindsay Killin, Brett Garton

DATE: 23/1/2012

SYSTEM: Feed Supply Bin and Conveyors LEADER: Dean Shewring

DRAWING: C143-PF-96D-DTDU-10001 Rev B MINUTES BY: Peter O’Dea

No. GUIDE WORDS POSSIBLE CAUSES CONSEQUENCES EXISTING

SAFEGUARDS

ACTION RECOMMENDED BY DONE

1. General Discussion

Bricks, rubble and oversized material, clay etc

Feed interrupted due to blockages or equipment damage

No need for hopper screen or clay breaker as pre-screening. will be done in the feed soil building

No further action required - -


Chemical (i.e. from the contaminated soil) attack on conveyor belts

Belt failure, maintenance

Will use chemical resistant belts



Rain Increased moisture impacts process

Conveyor covers to be installed


4. High Flow / High Level

Front end loader (FEL) overfills hopper

Spill to the bunded building floor

DTD operator in contact with FEL operator, any spilt soil can be swept up and reprocessed

Review the need for providing a mirror or screen in the FEL cabin so the FEL driver can see the level in the feed hopper

LK





DATE: 23/1/2012




SAFEGUARDS


5. Low Flow / Low Level

Soil clumps in hopper

Potential to fall onto the belt below (damage) and possibly cause blockages

Steep sided hopper minimises the risk of material hold-up on the hopper walls. Can adjust the gap below the hopper during commissioning


6. Zero Flow / Empty

Hopper empty Only financial – keep burning gas etc

Process controls come into effect to trip downstream fired appliances



Feeder fails Hopper full of material. Confined space entry to unblock

Routine checks on belt feeder during shutdowns, confined space risk assessment

Preventive maintenance procedures to emphasise belt feed conveyor checks

BG


Feeder fails (as above)

Hopper full of material. Confined space entry to unblock

Routine checks on belt feeder during shutdowns, confined space risk assessment

Review the need for hatches etc in the feed bin walls for ease of clearing material provided they also do not hold up material

LK





DATE: 23/1/2012




SAFEGUARDS



Spillage from conveyors

Clean-up. Damage to adjacent equipment

Scrapers prevent return below belt. Canopy over conveyors

Provide a cover around the slinger conveyor to prevent any spilt soil damaging adjacent gas burner and other equipment


Friction, e.g. from wood stuck on belt etc

Conveyor belt fire with toxic products of combustion potentially smoke logging the building

Fire hose nearby. Building vented through carbon filters

Include in the fire safety study assessment of belts fires and the risk to emergency responders from toxic products of combustion

LK


Plant outage Potential for conveyor belt fire on restart if material dries out / solidifies

Slinger conveyor can be run backwards for material to be collected in a truck, i.e. to clear the conveyors


12. Reverse Flow Belt stops on the inclined conveyor and runs back due to soil load

Spillage at bottom requiring cleaning up

Back stop provided on the conveyor


13. Impurities Asbestos cement sheeting pieces in the feed

Exposure to personnel who contact the treated soil and maintain the plant

Will be removed in accordance will agreed practices by licensed contractor






DATE: 23/1/2012




SAFEGUARDS


14. Impurities PPE disposed of via the process

Possibility of embers getting to the baghouse and causing damage to the filters

Will be collected and disposed of as special waste


15. Plant Items Lack of access for maintenance and operational checks

Reduced online time Include in the project plan an operability and maintainability access review to all equipment items

16. Plant Items Feed soil building emission control system out of service

Atmosphere unsuitable for personnel

Likely to be confined space entry if the feed soil building emission control system fails

Risk assessment, including on confined space entry, required to determine suitable safeguards for people entering the feed soil building when the emission control system fails

17. Plant Items Wayward FEL operation etc

Damage to feed hopper, conveyors etc

Will provide Jersey barriers


18. Electrical Magnetic field from tramp metal collector

Impact on people with pacemakers

Check impact of magnet on implanted pacemakers and any other critical electrical devices

BG





DATE: 23/1/2012

SYSTEM: Dryer and Cyclone LEADER: Dean Shewring



SAFEGUARDS


19. General Discussion (note the cyclones remove particles to 30 microns)

LEL exceeded in the dryer

Explosion With the soil at Villawood, the LEL cannot be exceeded. Therefore do not need pop-off damper and other such provisions



Knockout box blockage

Dryer full of soil requiring confined space for cleaning

Low soil temperature and position switches on the sluice gate or rotary valve will initiate action prior to significant consequential impact



High gas flow Overheating of materials and hence the potential for equipment damage

Plant will shut down from high temperature in the flue gases (back up thermocouples provided). Steel designed for 650 deg. C






DATE: 23/1/2012




SAFEGUARDS



Low solid separation in cyclones from a plant turndown

Baghouse overloaded Cyclones designed for minimum turndown of the burner



Unplanned plant shutdown

Material sitting hot in the bottom of the dryer can deform the dryer drum

Drum must be able to turn

Make provisions to turn the drum in case of plant, including power, shutdown, e.g. manual jogging

KC

24. Reverse Flow Burner continues to run when the ID fan stops

High temperature damage to the dryer or injury to personnel if flames are emitted from the dryer

Run on of the fan when shutting down and the draft from the stack will initially prevent damage and the burner flame is contained within the dryer, i.e. no potential for impact on personnel


25. High Temperature

Hot exterior of dryer and ductwork

Burns to personnel Personal protection, e.g. mesh guards or insulation, will be provided for surfaces over 60 deg. C






DATE: 23/1/2012




SAFEGUARDS


26. Plant Items Dryer flight breakage Equipment damage Routine maintenance checks and operator response to noise from within the dryer


27. Electrical Lightning Instrument damage Review the need for lightning (surge) protection of the instruments

KC

28. Instruments Ensure redundant pressure transmitters on the dryer, i.e. separate transmitters for control and trip actions

KC





DATE: 23/1/2012

SYSTEM: Thermal Oxidiser LEADER: Dean Shewring

DRAWING: C143-PF-96D-DTDU-10006 Rev A MINUTES BY: Peter O’Dea


SAFEGUARDS



Burner continues to run when the ID fan stops

High temperature damage to the burner or injury to personnel if flames are emitted from the burner

Run on of the fan when shutting down and the draft from the stack will initially prevent damage and the burner flame is contained within the burner, i.e. no potential for impact on personnel



High feed rate Thermal oxidiser (TO) residence time less than design

TO designed for > 2 seconds at maximum flow plus there is some extra time in the ducts to the baghouse



Buildup of slag in bottom of TO

Shutdown for cleanout Special burner / inlet gas design eliminates creation of sticky particles and agglomeration






DATE: 23/1/2012




SAFEGUARDS


32. Low Pressure ID fan draws too much flow

Worst case – could extinguish burner

Burner management system takes control, i.e. flameout detector shuts of the natural gas flow



Too much natural gas flow due to the control temperature transmitter reading too low

Equipment damage TO temperature trips plus there are also downstream temperature controls



Refractory failure Shell temperature rises (would probably see glow on the outside of the shell)

Plant operators will regularly shoot measurements with an infrared gun to detect hot spots


35. Low Temperature Loss of process control due to the control temperature transmitter reading too high

Fail to achieve regulatory destruction temperature

Thermocouples in series will pick up temperature discrepancies. Calibration instrument has been purchased






DATE: 23/1/2012




SAFEGUARDS


36. Low Temperature Emergency stop Residual material in the TO cools with potential to form other compounds, e.g. dioxins, furans

Slow cooling allows plant to be purged of gases using ID fan


37. Plant Items Flame impingement on shell opposite burner

Damage to vessel shell Burner entry is longer than burner flame length so direct flame impingement not expected


38. Plant Items Dust in the TO Flame detector does not see the flame and hence nuisance trips

Flame sensor is self-checking and air purged. System fails safe






DATE: 23/1/2012

SYSTEM: Evaporative Cooler including the Air / Water Flows

LEADER: Dean Shewring



SAFEGUARDS



Power failure Loss of water flow leading to high temperature and hence damage to equipment, e.g. the downstream scrubber

Inlet water valve fails open

Show the inlet water valve on the P&ID to fail open – designate as FO

KC


Rapid quenching does not occur

Dioxin formation Design is to quench to below 200 deg. C in 1 second



False low temperature reading at the outlet duct

Too much water flow resulting in pooling in the vessel bottom causing corrosion

Water will evaporate. Operator is constantly observing temperature to the baghouse

Review the need to install a low temperature alarm on the existing downstream thermocouple

RM


Dilution air damper open when it should not be

Nothing unsafe just a change in plant pressure

Will be detected through plant pressure controls






DATE: 23/1/2012





SAFEGUARDS



ECU (emission control unit) water pump keeps running when the evaporative cooler is shutdown

Bottom of the evaporative cooler floods

Procedures dictate pumps to be manually shut down when the plant stops. Water will come out the dilution air damper and become visible



Loss of water flow High temperature and hence damage to equipment, e.g. the downstream scrubber

Dilution air damper opens. If control not regained, plant trips

Dilution air damper to be as close to the evaporative cooler outlet duct as possible for effective cooling

KC


Low air flow, even if air pressure is maintained due to the air nozzle clogging

Large water particles created. Inefficient cooling. Control system calls for more water

Operator is constantly observing temperature to the baghouse and a low temperature alarm


46. Reverse Flow Hot gases out the open dilution damper??? - no record of this happening

Burns to nearby personnel

Damper located sufficiently high to avoid damage






DATE: 23/1/2012





SAFEGUARDS


47. Impurities Oil from the air compressor

Could send some of the stack readings high

The compressor will be oil-free or have a coalescing filter

Confirm compressor selection and hence no oil will flow to the evaporative cooler

LK

48. Change in Composition or Concentration / Two-Phase Flow / Reactions

Poor spray nozzle atomisation

Pooling in the vessel bottom causing corrosion

Nozzles can be withdrawn and tested


49. Testing Bypass valves on the air or water supply left open

No serious outcome Bypasses are useful for maintenance purposes and are to be retained






DATE: 23/1/2012

SYSTEM: Baghouse and Dust Screws LEADER: Dean Shewring



SAFEGUARDS



Inadequate air pulsing

Bags become blinded High differential pressure alarm

Review the air pulsing duration and frequency in the detailed design

RM


Dust in the bottom of the baghouse plus moisture, e.g. during a shutdown

Dust goes solid and hence maintenance access is required

Procedure is to run and empty the dust screw for prolonged shutdowns



Backup of dust if a screw conveyor fails

Dust is held-up in the system

The last screw runs faster than the 2

nd last

which runs faster than dust screw at the baghouse bottom to prevent dust being held-up


53. Impurities Torn bags falling onto the dust screw in the bottom of the baghouse

Dust screw blocked A grate is provided at the bottom above the baghouse dust screw


54. Plant Items Bag failure Dust not collected PM10 analyser and low differential pressure alarm






DATE: 23/1/2012

SYSTEM: Baghouse and Dust Screws LEADER: Dean Shewring



SAFEGUARDS


55. Plant Items Moisture ingress Corrosion, e.g. of the baghouse dust screw conveyor

Appropriate materials of construction






DATE: 23/1/2012

SYSTEM: Scrubber (gas stream to atmosphere) including the Induced Draft Fan




SAFEGUARDS



HCl will be present at elevated temperatures

Corrosion and hence equipment damage

Appropriate materials of construction will be provided



Low plant feed rate Low stack velocity, poor dispersion

The stack top diameter will be such that the minimum velocity to ensure good dispersion will be maintained at the design plant turndown


58. Impurities Baghouse failure Solids through to the scrubber

TDS (total dissolved solids) analyser provided


59. Plant Items Stack top silencer corrosion

Higher risk maintenance due to work at heights

Fan is silenced. Unsure if the stack top needs to include a silencer

Check the need from the noise studies for a stack top silencer – not preferred as it will be difficult to maintain

POD

60. Plant Items Stack top silencer corrosion (as above)

Higher risk maintenance due to work at heights

Fan is silenced. Unsure if the stack top needs to include a silencer

If uncertain about the need for a stack-top silencer, make provision for bolting one on later (including allowance for the weight)

KC





DATE: 23/1/2012

SYSTEM: Scrubber (gas stream to atmosphere) including the Induced Draft Fan




SAFEGUARDS


61. Plant Items Caustic leak Splashing and corrosive burns to personnel

Safety showers Provide safety showers with insulated pipes (to prevent hot water flowing during high ambient temperatures), green fluoro light above the shower, a flow sensor to alarm when a person is using a shower and procedures for lone workers

LK




PROJECT: Orica, Villawood, DTD Project TEAM MEMBERS: Gwenda Lister, Keith Chapman, Rudy Maes, Lindsay Killin, Brett Garton

DATE: 27/1/2012

SYSTEM: Scrubber – Make-up Water Supply Feeds




SAFEGUARDS



Dust carryover from baghouse

Demister blockage and hence high scrubber differential pressure

Sprays onto demister, high differential pressure alarm across the scrubber



Power failure and the recycle pumps stop

Loss of containment of acidic gases to atmosphere

Emergency power generator feeds the scrubber pumps, analysers installed on the scrubber stack



Failure of the check valve to the scrubber quench

Caustic flows back to the towns water tank

The makeup water supply main block valve to the scrubber quench is normally closed and will only be opened when the scrubber recycle pumps are not operating






DATE: 27/1/2012





SAFEGUARDS



Review need for the low flow alarm on the make-up water supply line to the quench as this will be a nuisance alarm during normal operation when there is no flow in this line (i.e. as above, this line is left isolated when the scrubber recycle pumps are running)

RM


Check with BK the reason for installing the flow meter in the make-up water supply line to the quench given the operation is manual

POD


Show on the P&ID the sump pump and its controls

KC





DATE: 27/1/2012





SAFEGUARDS



Solenoid valve to the scrubber sump fails open

Scrubber sump fills and then overflows via the emergency overflow

Sump high level alarm. pH meter will detect a drop in pH. The emergency overflow is sized for all make-up water supply flows operating together at maximum rates. Bunded area if it does overflow

Show on the P&ID the 2nd

level detector in the scrubber sump to separate the control and trip functions

KC


Solenoid valve to the demister sprays is stuck closed

Buildup of solids on the demister resulting in high scrubber differential pressure

Scrubber DP high alarm Include in the functional description a low flow alarm that is only active when the solenoid valve to demister sprays should be open (i.e. to avoid a nuisance alarm when the solenoid is meant to be closed)

RM

70. Reverse Flow Acidic gases absorb back into the make-up water feed lines

Corrosion of the piping and piping items

Appropriate materials of construction, e.g. stainless steel or plastic






DATE: 27/1/2012





SAFEGUARDS


71. Plant Items Control valves wrongly selected, e.g. solenoids for larger (100 to 150 mm) lines not appropriate

Loss of plant control Correct valve selection Amend the P&ID to show actual types of valves: electric or pneumatic actuation

KC





DATE: 27/1/2012

SYSTEM: Scrubber Recycle LEADER: Dean Shewring



SAFEGUARDS



Scrubber recycle pump failure

Plant shuts down (accepted response)

Manual changeover of pumps



Pump seals fail Release of 80 C liquid. Slow leak only expected from these types of pumps

Operator regular inspection and maintenance as required



Overdosing caustic High pH – no significant consequences identified

pH meter will alarm high pH



Underdosing caustic (e.g. from pH meter drifting, failure to top up the caustic IBC)

Lack of absorption of acidic gases and hence atmospheric emission

Routine manual sampling of the scrubber recycle liquid. pH meter including a low alarm. CEMS stack analysers, e.g. NOx and SOx will also rise and alarm for operator response






DATE: 27/1/2012




SAFEGUARDS



Nozzles fall off the reflux distributor (screw type which can unwind)

Inadequate liquid / gas contact due to channelling in the packing

Nozzles to be screwed in tight and are replaceable through the side of the scrubber column



Loss of scrubber flow Increase in temperature in the plastic packing with possible damage

Correct packing selection

Ensure the scrubber packing can withstand higher temperatures due to deviations in the recycle scrubber flow rate


Valve left shut before the scrubber liquor analysers

Analysers do not detect changes in pH or conductivity hence the potential for poor scrubber performance

Operator observes signals not fluctuating, analysers in the stack will alarm

Include in the functional description flat-line detection on the signals from the pH and conductivity analysers

RM

79. Reverse Flow Recycle flow goes back to the caustic pumps

Overpressure, loss of containment at the caustic IBC

Pressure control valve in the common delivery line from the caustic pumps

Review need for a check valve in the common caustic pump discharge line

RM





DATE: 27/1/2012




SAFEGUARDS



Hot pipelines (i.e. approximately 80 C)

Burns on contact Pipes above 60 deg. C potentially in contact with personnel to be provided with personnel protection through insulation, mesh guarding, signage, etc


81. Impurities Iron oxide dust not collected in baghouse

Blockage in the scrubber

Operator checks for water discolouration


82. Change in Composition or Concentration / Two-Phase Flow / Reactions

Solids buildup in system

High conductivity but this is a slow process and can be controlled manually

Manual blowdown to control conductivity is appropriate. Therefore, delete the actuated blowdown valve and upstream / downstream isolation valves

83. Testing High flow when taking samples

Splashing Valves (e.g. gate type) that can be slowly cracked open, PPE






DATE: 27/1/2012

SYSTEM: Liquid Feeds to Pugmill LEADER: Dean Shewring

DRAWING: C143-PF-96D-DTDU-10009 & C143-PF-96D-DTDU-10003 Rev B

MINUTES BY: Peter O’Dea


SAFEGUARDS



Pump requires maintenance

The pump discharge (i.e. after the check valve) needs to be flushed for maintenance

Review the need for individual drain valves on the discharge of each pump (as per the scrubber recycle pumps) for maintenance purposes when the other pump is still operational


Power failure Loss of water to the pugmill – dust release in the area

Show the flow control valve to the pugmill as fail open on the P&ID


Hazop suspended until the liquid balance assessment is carried out on the liquid feeds to the pugmill. Preference is to use treated water instead of Towns Water for sustainability reasons. Note: the current design requires makeup water via the scrubber and hence excessive caustic usage will result. It is expected the liquid feed system design will change and then the HAZOP should be performed





DATE: 27/1/2012

SYSTEM: Soil to and from the Pugmill (including the cyclones underflow)


DRAWING: C143-PF-96D-DTDU-10002 & C143-PF-96D-DTDU-10003 Rev B

MINUTES BY: Peter O’Dea


SAFEGUARDS



Rock, metal piece, etc gets into the pugmill

Baghouse drive overloads and equipment damage

High current detected shutting down the pugmill



Screw conveyor below the cyclones or rotary valve stops

High dust flow to the baghouse

Pressure measurements and/or operator will shut down the plant



Loss of water Soil too hot, potential damage to conveyor belts, burns, etc. Potential for a build-up of solids in the dryer and hence heat damage to the dryer

High temperature alarms. Camera shows high dust. Constant operator attendance. Operator shuts down pugmill if it cannot be controlled

Show on the P&IDs a trip of the dryer if the pugmill is shut down

RM


Loss of water to the pugmill

Potential for burns from the hot treated soil

Temperature alarms. Operator intervention

Ensure barriers, etc so people cannot come into contact with hot material

LK





DATE: 27/1/12

SYSTEM: Overview LEADER: Dean Shewring

DRAWING: All Drawings MINUTES BY: Peter O’Dea


SAFEGUARDS


91. Toxicity No further issues identified with the overview guide words





PROJECT: Orica, Villawood, DTD Project TEAM MEMBERS: Bala Kathiravelu, Gwenda Lister, Lindsay Killin, Tai Truong

DATE: 26/6/12

SYSTEM: Caustic IBC and Pumping System LEADER: Dean Shewring



SAFEGUARDS



Note only: The caustic storage vessel will be an IBC – manual changeover via hoses to a second IBC about once per week (with a portable plastic bund underneath)



Note only: The pumps will be diaphragm pumps with internal pressure relief, manual changeover, located in a bund and a safety shower nearby






DATE: 26/6/12




SAFEGUARDS



PCV 1082C to have a pressure indicator integral to the valve to allow the operators to set the pressure on the regulator and monitor its performance

LK


Overdosing caustic pH exceeds limit In the scrubber recycle circuit – no significant consequences identified

pH meter and alarm (it is expected to be reliable in this service with routine maintenance)



Loss of containment, e.g. forklift tynes puncture the IBC, hose failure, etc

Potential to cause injury to personnel

P10 high pressure plastic piping, no joints outside the bunded area






DATE: 26/6/12




SAFEGUARDS



Pumping caustic when the plant is shut down

Scrubber sump overflow. Temperature rise due to heat of mixing

High level alarm in the scrubber sump

Determine the maximum temperature rise and whether there is a detrimental effect on the scrubber system materials of construction. Calculate the volume in the scrubber sump between the normal highest level and overflow to check that a maximum of 1 m

3 from an IBC will not result in

overflow from the scrubber overflow pipe. Review the need for a hard wired trip to stop the caustic pump if being run in manual. Also, review the need for PLC alarms to indicate that the caustic pump is left running in manual and hence the control system trips etc will not be functional

TT


Stormwater falling into the bunded area

Stormwater management required

Bunded area, sump, discharge to water treatment plant






DATE: 26/6/12




SAFEGUARDS



Pipe breakage, e.g. mechanical impact

Caustic leak with the potential to harm personnel

Strong materials of construction for the proposed tubing

Ensure that the small bore caustic piping is adequately protected from mechanical impact

LK


Empty IBC, leaks, pump not fast enough

Loss of acidic gas scrubbing

pH alarm and interlock, scrubber stack analysers and alarms



Valves shut, IBC empty, pump deadheaded

Potential to exceed the piping system design pressure for the deadhead case and hence result in a loss of containment of caustic which could harm personnel

Internal pressure relief to be included with the pump, pH meter and alarm in the scrubber recycle circuit


102. Reverse Flow No credible causes identified given the safeguards

Non return valve, PCV 1082C will close when the caustic pump stops, suction and discharge valves for the pump will also act to prevent reverse flow






DATE: 26/6/12




SAFEGUARDS


103. Low Pressure IBC vent left closed Suck in the IBC Procedures and training for bung removal or some IBCs have vents included



Heat of dilution with caustic and water

No significant consequences identified

Materials adequate for 100 deg. C


105. Low Temperature Standby pump freezes on cold night

No caustic flow to the scrubber when pumps changed over

pH alarm and interlock, scrubber stack analysers and alarms

Delete the standby pump and piping and provide a spare pump in store

LK

106. Low Temperature Pump pressure relief inlet and outlet lines freeze

Loss of deadhead protection for the caustic pump and hence the potential for a loss of containment of caustic which could harm personnel

Review the need for insulation or heat tracing on the pump pressure relief inlet and outlet lines

LK

107. Plant Items IBC changeover Potential incidents associated with forklift trucks and hose disconnection and reconnection

Review the layout for forklift accessibility as well as the operability of the caustic hose connections including hose draining

LK





DATE: 26/6/12

SYSTEM: Towns Water Tank LEADER: Dean Shewring



SAFEGUARDS



Thoroughly flush the Towns Water supply pipe during commissioning to ensure all residual solids are removed (plus check quality of gas supply with respect to solids in the pipeline as well)

GL


Ensure the Towns Water pipe from the Sydney Water main is large enough to avoid the need for a booster pump, i.e. delete the booster pump and fill the Towns Water tank directly from the Sydney Water mains supply

LK


Show other consumers of Towns Water on the drawing, e.g. safety showers, ablutions, etc. These off-takes are to be from the supply pipe upstream of the Towns Water tank for supply quality reliability (e.g. no process contaminants due to reverse flow)

LK


Supply pipe ruptured, e.g. by backhoe

Tank fails to fill. No water flow to the ECU, pugmill, scrubber, etc

Low pressure and flow alarms and trips on the downstream water users

Ensure the Towns Water supply line is away from the project excavation areas

LK





DATE: 26/6/12




SAFEGUARDS



Level control valve insufficiently open

Tank fails to fill. No water flow to ECU, pugmill, scrubber, etc

Low pressure and flow alarms and trips on the downstream water users


113. Reverse Flow The tank overflow is to be lower than the water inlet to ensure there the risk of reverse flow into the Towns Water supply line to the tank is as low as possible

114. Impurities Frogs, vermin, etc in tank

Blockage of the water supply pumps inlet strainers

Pump strainer maintenance and downstream pressure and flow alarms


115. Plant Items Locate the LCV close to the Towns Water tank roof manhole for ease of inspection and maintenance

LK

116. Plant Items Work at heights when maintaining the tank’s level transmitter

Potential for falls and serious injuries

Permit to work system including controls for fall prevention

Use a differential pressure transmitter for tank level measurement (located at grade) in lieu of an ultrasonic transmitter on top of tank

LK





DATE: 26/6/12




SAFEGUARDS


117. Plant Items Work at heights when maintaining the tank’s LCV

Potential for falls and serious injuries

Permit to work system including controls for fall prevention

Review to option for replacing the roof mounted level control valve to one at grade (i.e. eliminate the need for a float valve at the top of the tank and hence work at heights injuries)

LK

118. Instruments Failure of the sight glass

Water leaks Maintenance and replacement of the sight glass

Review type of sight glass level indication and also the need for a sight glass for LI1074 to minimise the risk of leaks





DATE: 26/6/12

SYSTEM: Towns Water Pumping Systems LEADER: Dean Shewring



SAFEGUARDS



The scrubber blowdown (max 20-40 l/min) will go directly to the pugmill from the discharge side of the scrubber recycle pumps, not via the pugmill water supply pumps. As this line has not been HAZOPed, perform a formal design change assessment when the final design details are known. Therefore, pumps PUI-0907 and 0908 are duty/standby and are the same design as the other water pumpsets shown on this P&ID

TT


Review the need to replace the 6 Y-type strainers with 2 strainers in the common suction line to all pumpsets (ease of maintenance)

TT


Add an isolation valve upstream of PCV1052 (to be consistent with the other water pumping systems design)

TT





DATE: 26/6/12




SAFEGUARDS



Running 2 pumps simultaneously

No significant consequences identified

Duty/standby selector switch. Flow controls downstream will ensure the users only take what water they need



Blocked strainers, valves gagged, pump problems

Loss of the required flow to the ECU, scrubber and pugmill (as previously HAZOPed above)

Alarms and trips at each user of the water, e.g. low pressure or flow. Critical pumps can be started manually when emergency generator started



Loss of water to the ECU

Potential for heat damage to the water spray nozzles when the plant is tripped on low water flow

Confirm that the nozzles are made from appropriate materials of construction for high temperature following a plant trip

LK





DATE: 26/6/12




SAFEGUARDS


125. Reverse Flow Loss of the quench water pumps to the scrubber

Potential for acidic mist to absorb into the water in the supply pipe to the scrubber and cause corrosion

As per Plant Items, review the materials of construction for all equipment throughout the plant

LK

126. Reverse Flow Pumps stops, e.g. loss of power

Water in the pipes to the ECU and scrubber flows back and hence drawing gases from these vessels, i.e. corrosion potential as above

As above, the correct materials of construction are to be confirmed


127. Plant Items Acidic vapours, etc throughout the plant

Corrosion of equipment as above

Review the materials of construction for all equipment throughout the plant

LK

128. Electrical Power failure Loss of critical equipment

Emergency generator Confirm the required items connected to the emergency power supply

BK





DATE: 26/6/12

SYSTEM: Instrument and Compressed Air LEADER: Dean Shewring



SAFEGUARDS



Review the need for the standby air compressor, including the need for the isolation valve on the discharge of compressor AC-1002. Delete if not required

LK


Historical incidents involving oil filled compressors running too hot and hence cracking the oil

The cracked oil can leave dust deposits within the piping system and hence is an internal dust explosion hazard

Running the air compressor within the design limits, routine oil sampling and replacement

The air compressor is to be oil free LK


Review the final design details from vendor for the compressor and dryers (HAZOP assumes desiccant dryer) including inlet air strainer, check valve to avoid depressurisation of the air receiver when the compressors trip, dew point measurement, weatherproofing to avoid rain ingress to the compressor suction, signals to control room, functional logic, etc

LK





DATE: 26/6/12




SAFEGUARDS



The maximum air pressure is to be designed for adequate operation of the ECU nozzles (possibly 10 barg plus)

LK


Update the air compressor P&ID to show all air users, e.g. the ECU

LK


Rationalise the number, location and set pressure for the pressure regulators (e.g. PCV1079A/B/C appear to be controlling the same pressure and hence there is the potential for these regulators to hunt). For the required pressure regulators, supply pressure indication for testing and monitoring purposes

LK


Make the complete system dry air (i.e. dry air is required to all users) to avoid wet air blocking the baghouse filter bags. This will remove the additional air receiver, associated equipment and controls

LK





DATE: 26/6/12




SAFEGUARDS



Regulator failure Potential for the maximum air supply pressure to be within the supply pipe to the final isolation valve at each air user

Confirm that the design is rated for full air pressure to the final isolation valves for each air user

LK


Loss of power No air to users Low pressure alarms and trips


138. High Pressure Compressor deadheaded

Potential for equipment damage and possible failure leading to missiles, i.e. harm to people and damage to equipment

Make sure the vendor package has appropriate safeguards for compressor deadhead and if a blow off valve / pressure safety valve is provided then it should not yield unacceptable noise levels (e.g. provide a silencer)

LK


Heat from 10 bar pressure requirement

Potential high temperature damage to the downstream equipment

Review the maximum compressor discharge temperature and ensure that adequate safeguards are included, e.g. ensure the compressor package has a cooler

LK





DATE: 26/6/12

SYSTEM: OVERVIEW LEADER: Dean Shewring

DRAWING: Caustic, Water and Air P&IDs MINUTES BY: Peter O’Dea


SAFEGUARDS


140. Commissioning Provide high point vents and low point drains for hydrotesting once the piping layout drawings are known

LK

141. Commissioning Foreign objects in the pipes during commissioning

Potential to damage equipment

Provide temporary cone strainers, remove sensitive instruments and valves, etc for line flushing during commissioning

LK

142. Commissioning Potential for dioxin formation from the plant

Impact to people and the business

Incorporate the learnings from the ATMR plant commissioning especially re dioxin prevention and control

TT

143. Commissioning Provide sufficient process sampling points between the main plant items to be able to measure gas composition and diagnose problems, e.g. levels of unwanted by-products

LK

144. Materials of Construction

Potential incompatibility of the materials of construction with the process materials

Corrosion and equipment failure with a loss of containment

Review the compatibility of the chosen materials of construction, including gaskets, with the process materials via the Hazard Study 1 chemicals compatibility of materials chart

BK




PROJECT: Orica, Villawood, DTD Project TEAM MEMBERS: Bala Kathiravelu, Gwenda Lister, Lindsay Killin, Tai Truong, Peter O’Dea, Rudy Maes, Keith Chapman

DATE: 19/10/12

SYSTEM: Air Compressor for the Evaporative Cooler


DRAWING: C143-PF-96D-CTCU-10010 (mark-up) MINUTES BY: Bala Kathiravelu


SAFEGUARDS



The tag numbers on the two air compressor, e.g. hand switches, need to be unique. Mark up the P&ID accordingly

KC

146. High Pressure Compressor high pressure protection for deadheading

The compressor is a screw compressor and hence the potential for overpressuring the discharge piping with possible failures leading to missiles

Check the vendor P&ID that high pressure protection is provided. Also, review the vendor supply details to confirm adequate controls and safeguarding is being provided, e.g. suction screen and an aftercooler and a high outlet temperature alarm

KC


Operating the oil flooded compressor (to be confirmed) at high temperatures

Potential to crack the oil and lead to a build-up on the inside of the pipes which can explode

Minute 130 (above) regarding the need for an oil free compressor is to be reconsidered. If the compressor is not oil free then provide an oil filter and confirm the operating temperature is less than 140 deg C exit the aftercooler

KC





DATE: 19/10/12

SYSTEM: Air Compressor for the Evaporative Cooler


DRAWING: C143-PF-96D-CTCU-10010 (mark-up) MINUTES BY: Bala Kathiravelu


SAFEGUARDS


148. Low Temperature Cooling of the air in the air receiver

Condensate will form and build-up within the air receiver

Manual draining Install an automatic condensate drain on the receiver(s?) with an isolation valve and bypass valve for maintenance

KC





DATE: 19/10/12

SYSTEM: Pugmill Water System (pumps 0907 and 0908)


DRAWING: C143-PF-96D-CTCU-10009 and 10003 Rev D

MINUTES BY: Bala Kathiravelu


SAFEGUARDS



Following discussion, the scrubber blowdown is to be sent to the effluent treatment system. The main issues being: 1. The potential for corrosion in the pugmill system, e.g. high chlorides levels in a hot, wet environment or from changes in pH 2. Contamination of the treated soil 3. The historical problems with solids in the scrubber blowdown causing blockages (e.g. of the spray nozzles) and settling (e.g. within tanks), and 4. That the treated water can be rerun and hence is not a potential loss from plant. Therefore, Towns Water is to be used for the pugmill water spray systems. Also, provide appropriate connections for a possible future scrubber bleed blowdown tank (if required) and allow adequate space in the plot planning

KC





DATE: 19/10/12






SAFEGUARDS



Need to balance flow to pugmill sprays

Mark up the P&ID to show individual isolation supply valves to each pugmill spray nozzle

KC


P&ID correction Show PCV1052 controlling upstream pressure as this valve is used for deadhead protection for the pumps

KC


P&ID correction The Towns Water pumps kickback lines are to be top entry into the Towns Water tank (to prevent reverse flow issues from submerged entries). Therefore delete the isolation valves at each kickback line nozzle to the Towns Water tank and the check valve in the kickback line for pumps 0907 and 0908

KC


P&ID correction FCV 1019 is to be a modulating valve and it is to fail last position on loss of air to the actuator, i.e. show a mushroom head valve and FLP on the P&ID

KC


P&ID correction Provide an isolation valve on PI 1019B (consistent with all PIs)

KC





DATE: 19/10/12






SAFEGUARDS



P&ID correction Delete the line on P&ID 1003 shown as “Cooling Water from Scrubber” to the pugmill sprays (as this was formally used for return scrubber liquid – no longer required) and also delete PT 1019C and the associated alarms on this line

KC


Spray nozzle unwinding and falling off

Too much water flow to the pugmill – no significant consequences identified

Spot weld the spray nozzles onto the pipes to prevent them from falling off

KC


The pugmill pump stops and water syphons forward through them to the pugmill

Too much water flow to the pugmill – no significant consequences identified

Include in the functional description the need to have FVC 1019 & SV 1019 closed when the pugmill pump stops

KC


Note that the scrubber blowdown is approximately 80 deg C

Potential for burn injuries if personnel contact hot surfaces

Provide appropriate personal protection to avoid burns for the scrubber blowdown line

LK





DATE: 19/10/12

SYSTEM: Overview - Air Compressor to the Evaporative Cooler and the Pugmill Water System


DRAWING: C143-PF-96D-CTCU-10009 and 10003 Rev D, C143-PF-96D-CTCU-10010 (mark-up)



SAFEGUARDS


159. No further significant hazardous events or operability problems identified for these systems using the “Overview” guide words

- -




PROJECT: Orica Villawood Water Treatment Plant

TEAM MEMBERS: Bala Kathiravelu, Peter O’Dea, Pearce Anderson, Richard Giles, Lindsay Killin

DATE: 29/11/12

SYSTEM: High Capacity Settling Tank LEADER: Dean Shewring

DRAWING: SAS10883-301 Rev A MINUTES BY: Lindsay Killin


SAFEGUARDS



Delete the butterfly valve on the clarified liquid line from the settling tank as this line is free draining and hence does not need to be isolated

PA


Mark up the P&IDs to show all line sizes, e.g. the clarified water line from the settling tank

PA


Delete the additional diaphragm valve downstream of the settling tank sump gate valves. The gate valves are at ground level (i.e. accessible) and can be used for isolation for pump flushing etc instead

PA


Losses of containment from the coagulant pumping system

Potential environmental consequences of overflow to the ground

System leak checked prior to operation, the coagulant IBC is bunded

Ensure the coagulant pumping system is within the IBC bunded area to contain any leaks. Apply this action to all chemical dosing systems

PA






DATE: 29/11/12




SAFEGUARDS



Solids fouling of the static mixer on the inlet to the settling tank

Plant downtime for maintenance

Delete the static mixer and add the coagulant upstream in the feed line to allow sufficient line length for mixing

PA

165. Reverse Flow Confirm that design will prevent reverse flow of coagulant to the upstream sources (these upstream sources are to be shown on the P&ID)

PA

166. High Pressure Deadhead of the sludge pump

Potential to rupture the downstream piping system

Operators to keep the isolation valves open during normal operation

Replace the high pressure instrumented protection system (i.e. a potential Safety Instrumented Function to AS61511) with a suitable mechanical over-pressure device, e.g. a PRV or kick back line (Note: consider the implications of sludge fouling a PRV). Also, note that if a PRV is installed, it should be installed immediately downstream of the pump for the case where the NRV is stuck in the closed position

PA

167. Plant Items Confirm all off-takes from the sludge lines are horizontal to vertical to prevent settling and compaction of solids in the branches

PA






DATE: 29/11/12




SAFEGUARDS


168. Plant Items Preference is to not use PVC due to interaction between solvents and plasticiser. If used, then the preference is to use UPVC (i.e. un-plasticised PVC)

PA

169. Plant Items Operator leaves the sludge pump running for too long

Overfilling the sedimentation tanks

Procedures and training Install a timer on the sludge pump to prevent excessive amounts of water being flushed to the sedimentation tanks and also to allow adequate flushing of sludge pump and lines during pump operation

PA

170. I Plant Items Isolation of water in the aboveground piping

Potential for heating by the sun and thermal overpressure, i.e. piping system failure

Procedures and training Include in the SOPs the need to keep aboveground pipework open (i.e. not isolated) to prevent thermal overpressure from isolated liquid being heated by the sun

PA

171. P Plant Items Solids settling in the feed lines to the settling tank

Fouling of the feed lines Provide means to allow flushing of the inlet lines to the settling tank. Treated water to be used (not potable water due to the risk of reverse flow and hence contamination)

PA






DATE: 29/11/12




SAFEGUARDS


172. Plant Items Delete the second isolation valve on discharge side of the coagulant dosing pump as it is only isolating a reducer and double isolation is not required. Apply this action to all chemical dosing systems

PA

173. Instruments Provide a diaphragm connection to all instruments on sludge lines in the plant to prevent blocking of the impulse lines from the solids

PA






DATE: 29/11/12

SYSTEM: Feed Tank System including the Untreated Water Basin


DRAWING: SAS10883 – 301 Rev A, SAS10883 – 302 Rev 0

MINUTES BY: Lindsay Killin


SAFEGUARDS



Rain and the water treatment plant not available

Overfilling the untreated water basin

Procedural control monitoring water levels

Install a flashing light (to be visible from the DTDU) and/or use a SMS text warning service to alert the operators of any unacceptable process conditions when the plant is unattended

PA


Draining of both sedimentation tanks to the feed tank, e.g. manual valves passing or left open

Potential to initially overflow the feed tank and then overflow the pump well bund

Operator to check level in the feed tank prior to discharge from the sedimentation tank. High level alarms and trip 2.1 to stop some feed pumps into the feed tank

Review the need to overflow the pump well bund to the adjacent bunded area given the current containment areas capacities

LK


Operator does not perform recycle from the break tank to the feed tank during start up

Higher than normal solids through to the zeolite filters resulting in plant recovery impacts due to the need to backwash the filters

SOPs and training Review the need for automating the break tank recycle valves to lower the risk of this occurring, e.g. two actuated valves for flow path determination after the transfer pump

PA






DATE: 29/11/12

SYSTEM: Feed Tank System including the Untreated Water Basin


DRAWING: SAS10883 – 301 Rev A, SAS10883 – 302 Rev 0



SAFEGUARDS


177. Impurities Foreign objects entering the un-treated water basin

Blockage and/or damage to the raw water feed pump

Install a screen on the inlet to the raw water feed pump. Apply this action to all sump pumps in the plant

PA

178. Instruments Plant inlet water flowrate monitoring for mass balances and performance checks

Provide means to monitor the water flow into the mixing tank, e.g. replace the flow switch with flow meter and a low flow trip

PA






DATE: 29/11/12

SYSTEM: Flocculation Tank and Chemical Dosing Systems (HAZOPed by Difference)


DRAWING: SAS10883 – 302 Rev 0 MINUTES BY: Lindsay Killin


SAFEGUARDS



Review the possibility of overflowing from the flocculation tank chamber 1 to chamber 2 to minimise risk of short circuiting in the first chamber and hence inadequate mixing (i.e. use a higher elevation overflow line)

PA


Markup the P& ID to show the drain valves on the flocculation tank chambers

PA


Show both isolation valves on the outlet of flocculation chamber 2 from the flocculation tank

PA


Caustic line breakage through high pressure / damage

Potential to splash a person and cause a corrosive burn

System to be leak checked prior to use, high pressure tubing to be used

Add a flow switch alarm to the water supply to the proposed safety shower in case a lone worker requires assistance when using the safety shower

PA


Loss of containment of flocculant

Slip hazard Utility station to be added to allow wash down of any spills of flocculant

PA






DATE: 29/11/12





SAFEGUARDS


184. Reverse Flow Failure of the flocculant discharge non-return valve and the pump suction and discharge (check) valves

Drain the entire flocculation tank, including both chambers, to the flocculant IBC

Maintenance on the piping system and check valves

As above, preference is to overflow from the mixing tank (chamber 1) at a high point which would be ideal for the flocculant addition point to reduce the chance of this reverse flow scenario. Further review required

PA


Water supply line to the safety shower / eyewash heated by the sun

Hot water from the safety shower eyewash with the potential to render the unit inoperable

Ensure the potable water to safety shower eyewash is protected from reaching high temperature due to heating by the sun

LK

186. Low Temperature Cold winter night Potential to freeze caustic (46 to 50%), in particular, in small bore lines that have intermittent flows

Review means to ensure the caustic does not freeze in the dosing lines

SA






DATE: 29/11/12





SAFEGUARDS


187. Plant Items Personnel or wildlife contact with caustic when splash filling into the mixing tank

Corrosive burn injuries Caustic not dosed during maintenance (the system is shut down). Plant will be shutdown during maintenance of the pH probe

Perform a risk assessment on the caustic dosing point for this scenario to check if additional safety controls are required, e.g. cowling around the caustic dosing point

SA






DATE: 29/11/12

SYSTEM: Lamella Settlers LEADER: Dean Shewring

DRAWING: SAS10883 – 303 Rev A MINUTES BY: Lindsay Killin


SAFEGUARDS



Apply the common actions from the settling tank sludge pump as appropriate, i.e. actions 7, 8 and 10. No further significant issues identified

PA






DATE: 29/11/12

SYSTEM: Break Tank / Zeolite Feed Tank (HAZOPed by Difference) and the Filter Pumping System, i.e. Filters on-line


DRAWING: SAS10883 – 303 Rev A, SAS10883 – 304 Rev A



SAFEGUARDS



Review the need for having two tanks in series, i.e. the break tank and the zeolite feed tank. Can the plant be operated adequately with only one tank (e.g. consider sludge fouling the filters at a higher frequency if only one tank was used). Delete one tank from the scope if two are not required

PA


Operator leaves one or more filter manual valves in the incorrect position during or after a backwash operation

Unwanted misdirected flows, e.g. backwash water to the GAC feed tank

SOPs and training acceptable given the consequential impacts


191. High Pressure Zeolite filters outlet valves shut

Potential to exceed the design pressure of the filters from the filter feed pumps

PSH on filter feed pumps discharge, however, its set point is unknown

Confirm that there are adequate safeguards to protect against over-pressure of the filters as they are designed for maximum pressure of 250 kPag

PA






DATE: 29/11/12

SYSTEM: Break Tank / Zeolite Feed Tank (HAZOPed by Difference) and the Filter Pumping System, i.e. Filters on-line


DRAWING: SAS10883 – 303 Rev A, SAS10883 – 304 Rev A



SAFEGUARDS


192. Testing Install an analysis point on the common line to the GAC feed tank to allow the operators to test the performance of the zeolite filters

PA






DATE: 29/11/12

SYSTEM: Zeolite Filters Backwashing LEADER: Dean Shewring



SAFEGUARDS



Install an additional valve downstream of zeolite filters to isolate the filter system from the GAC feed tank for backwashing of the zeolite filters

PA


All three filters become blinded

Inability to backwash Provide means to backwash all three filters when blinded, e.g. install an additional hose connection on common backwash inlet to all three filters for connecting a hose (must consider the maximum water supply pressure to ensure this does not exceed the filter maximum pressure) or install a filter bypass line to allow backwash with non-filtered water from the zeolite filter feed pump

PA

195. Instruments Review the need for the flow switch after the zeolite feed pumps as the PSH can be used for filter blockage and deadhead protection. Delete if not required

PA






DATE: 29/11/12

SYSTEM: GAC Feed Tank System (HAZOPed by Difference) and GAC Filters




SAFEGUARDS



Update the P&ID to show the tank liquid outlet nozzle isolation valve

PA


Operator leaves one or more GAC manual valves in the incorrect position

Unwanted misdirected flows, e.g. non-treated water to the treated water basins, or deadhead of the GAC feed pump

SOPs and training acceptable given the consequential impacts



Two pumps in operation

Potential to carry over activated carbon to the downstream treated water tank and beyond

The stand-by pump is to be removed from the field and used as a hot spare (i.e. two pump operation not possible). Also, include in SOPs the need to only run one pump at a time in the future to avoid fluidisation of the GAC if a second stand-by pump is installed

PA


Incorrect valve alignment

Potential contaminants going into the treated water feed tank and/or dead head the GAC feed pump

Testing of the treated water prior to discharge to the sewer and the ability to rerun off-spec water through the plant

Include in the SOPs the need for supervisory checking of valve positions after a GAC unit valve change / change over

LK






DATE: 29/11/12





SAFEGUARDS



GAC purifier feed pump is larger in size than the current pump

Increase pumping rate has potential to fluidise the carbon bed and hence the increase risk of carry-over of GAC

Confirm the new pump will not result in fluidisation of the GEC purifiers

SA


GAC feed pump stops

Water in the GAC purifiers will drain down to the treated water tank and form a vacuum in the upper sections of the GAC Purifiers. Also, if the pump check valve fails, the pressure in the GACs will be close to a full vacuum when draining back to the GAC feed tank

Confirm that the GAC vessels are adequately rated for the maximum vacuum that can be generated

PA






DATE: 29/11/12





SAFEGUARDS


202. High Pressure New pump feeding the GACs

Potential to exceed the maximum design pressure for the GAC vessels as this is a larger duty pump

Confirm that the maximum design pressure of the GAC vessels exceeds the maximum supply pressure from the new pump. If not, review the need to replace the existing PRVs with larger valves

LK

203. Impurities Extended shutdown (i.e. 4-5 weeks or more)

Potential for biological growth on the GAC and hence deactivation

Install a recirculation line from the outlet of the GACs to the GAC feed tank to allow GAC recirculation during downtime

PA

204. Impurities Fines from the initial flushing of the zeolite filters

Blinding of the activated carbon and hence deactivation (as above)

Include in the SOPs the need to rinse the zeolite filters to the sedimentation tank via the rinse valves

PA

205. Testing Determine availability of methods to get quick turnaround on GAC bed analyses, or indicator tests while awaiting lab results

PA






DATE: 29/11/12





SAFEGUARDS


206. Plant Items Confirm the mechanical integrity of the equipment available in the existing parts of the WTP including the structures (e.g. stairs and platforms) and the vessels (e.g. routine pressure vessel inspection and testing required?)

LK





TEAM MEMBERS: Bala Kathiravelu, Peter O’Dea, Pearce Anderson, Lindsay Killin

DATE: 30/11/12

SYSTEM: Treated Water Basin System LEADER: Dean Shewring



SAFEGUARDS



As the treated water tank and pump are not required to recover off-spec material etc then these can be removed from the design. To prevent draining and hence forming a vacuum in the GACs when the GAC feed pump stops install a motorised solenoid valve on the common outlet line (close to the GACs) which is to close the when the GAC feed pump stops. Also, include position switches on this motorised valve to allow interlocking to pump operation, i.e. prevent pump operation if the motorised valve is stuck closed and raise an alarm if this valve is open when it should be closed. The valve should fail to the last position

PA


Retain means to recirculate the basins, e.g. for pH correction. Note: sampling can be achieved by manually dipping the basin

PA






DATE: 30/11/12

SYSTEM: Treated Water Basin System LEADER: Dean Shewring



SAFEGUARDS



Passing butterfly valve

Relatively small amount of off-spec material could flow to sewer but probably still on spec in relation to trade waste consent

Change the destination selection valves in pipes from the basin to ball valves. Establish a protocol in which Orica and EPS agree on discharge to the sewer to minimise the risk of off-spec discharge, e.g. supervisory checks that the valves are in the correct position prior to discharging to the sewer

PA


Off-spec treated water running to two basins, e.g. basin inlet valve passing or inadvertently left open

Putting an on-spec basin off-spec and hence having to rerun a basin back through the plant prior to discharge

Visible inlets to basins to make sure the operator can check visually during inspections

Change the three basins inlet butterfly valves to ball valves for improved reliability of shut-off. These are to be lockable ball valves to allow full isolation of basins

PA

211. Low Pressure Motorised valve to treated water basins closes quickly

Potential to form a vacuum downstream of the motorised valve and suck in the poly pipe

Provide means to mitigate the vacuum that could be formed, e.g. install a vent (vent could have a non-return valve to prevent water discharge but allow air in) or a vacuum breaker

SA






DATE: 30/11/12

SYSTEM: Sedimentation Tanks LEADER: Dean Shewring



SAFEGUARDS



Review the option of using bulkabags under the sedimentation tank drains instead of the drying beds to improve ease of handling of sludge

LK


Mark up the P & ID to show the bund under the sedimentation tanks

PA






DATE: 30/11/12




SAFEGUARDS



Sludge caking within the sludge outlet line

Inability to drain the sedimentation tank

Lines can be rodded. Sedimentation tank to be isolated by the first outlet valve and the second outlet valve is to remain open (to prevent sludge blockages between these two valves). For improved operation, the preference is to keep one tank offline and hence have the option to use this standby tank should the first tank/lines become blocked

As an option in the SOPs put the sludge line from the high capacity settler to only one of the sedimentation tanks, i.e. minimise the risk of blocking both tanks with the higher sludge containing stream

PA


Fouling of the sand dryer bed with the sludge

Inability to drain through the beds

Operation to be reviewed during commissioning and bulkabags considered as alternative option to beds if the beds are blocked too often

LK






DATE: 30/11/12




SAFEGUARDS


216. Plant Items Personnel exposed to DDT etc contained within the sludge

Health impacts on personnel

SWMS/JSA to be performed on sludge handling, e.g. disposal via the DTDU


217. Instruments Position the level switch in each sedimentation tank for ease of maintenance access and away from the sludge inlet to avoid any materials potentially seizing up the instrument

PA






DATE: 30/11/12

SYSTEM: Overview LEADER: Dean Shewring

DRAWING: All WTP P&IDs MINUTES BY: Lindsay Killin


SAFEGUARDS


218. Commissioning Contamination of the pressure test / wash water with existing contaminants in the plant

Problems in disposing of the wash-water

Include in the commissioning plan the ability to store water used to rinse and test the plant and equipment for processing through the plant at a later date. Also, avoid using detergents / dispersants when cleaning. These can cause future issues with the settling processes

LK

219. Materials of Construction

Review the existing and proposed materials of construction to ensure that potential contaminants do not react / interfere with plant components. Analysis is also required for the potential for construction materials being impregnated by contaminants and therefore being unsuitable for reuse on future projects or difficult to dispose of

PA



6 REFERENCES

1 Department of Planning, Hazardous Industry Planning Advisory Paper Nº 8 - HAZOP Guidelines, NSW Government, Sydney

Orica Villawood HAZOP Report Rev E

Documents

Transcript of Orica Villawood HAZOP Report Rev E