PINNACLE RISK MANAGEMENT PTY LTD - HAZOP STUDY …

OricaVillawoodHAZOPActionStatus_16 Oct 14 14 1

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 A 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

Soil management plan to include soil pre treatment in FSB to remove oversized material, and screening and blending to produce a dry (non adhesive) and homogenised feed in terms of contaminant profile.

LK Done


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

Belt failure, maintenance

Will use chemical resistant belts. The proposed belt feeder has been replaced by a JC Steel live bottom screw conveyor comprising 4 rows of screws. The design is identical to the feeder that has been reliably used on the ATMR thermal plant

No further action required KC Done. December 2012


Rain Increased moisture impacts process

Conveyor covers to be installed

No further action required KC Done.




DATE: 23/1/2012



No. GUIDE WORDS


SAFEGUARDS


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 Camera installed in this area

LK Complete – Feed Bin Camera installed

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

No further action required KC Done.

6. Zero Flow / Empty

Hopper empty Only financial – keep burning gas etc

Process controls come into effect to trip downstream fired appliances

No further action required RM Done.




DATE: 23/1/2012



No. GUIDE WORDS


SAFEGUARDS



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 Maintenance schedule has a daily

inspection for soil bridging in the bin during operations and a fortnightly

inspection and clean out if necessary of residual soil when plant shut down.


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. (Group agreed that JC Steel feeder will provide reliable operation. If required soil in hopper will be manually removed by following unscheduled maintenance procedures)

LK Done


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

KC Done.




DATE: 23/1/2012



No. GUIDE WORDS


SAFEGUARDS



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 Done.


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, FEL bucket, i.e. to clear the conveyors

No further action required Provide emergency power back up for slinger belt.

RM Done

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

No further action required KC NA

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

No further action required Refer to item 1. Part of OH&S plan

LK NA

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

No further action required Part of Waste management plan.

LK NA

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

LK Done.




DATE: 23/1/2012



No. GUIDE WORDS


SAFEGUARDS


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

LK Audible and visual alarm installed in the FSB. SWMS notes

requirements to evacuate when alarm triggered.

17. Plant Items Wayward FEL operation etc

Damage to feed hopper, conveyors etc

Will provide Jersey barriers

No further action required LK Wheel stops installed.

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 Signage to be installed.

LK Done




DATE: 23/1/2012

SYSTEM: Dryer and Cyclone LEADER: Dean Shewring


No. GUIDE WORDS POSSIBLE CAUSES CONSEQUENCES EXISTING

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

No further action required NA


Knockout box blockage

Dryer full of soil requiring confined space for cleaning

High dryer drive amp alarm which trips the feeder

No further action required RM NA


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

No further action required RM NA


Low solid separation in cyclones from a plant turndown

Baghouse overloaded Dryer installed with big knock out box. Group agreed Cyclone outlet TC should be installed

Install cyclone outlet TC KC Done


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 Backup power being used to drive drum during power failure

KC Done.




DATE: 23/1/2012




SAFEGUARDS


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


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 Grounding rod program will be established.

KC Done




DATE: 23/1/2012




SAFEGUARDS


28. Instruments Ensure redundant pressure transmitters on the dryer, i.e. separate transmitters for control and trip actions Added second pressure transmitter to P&ID.

KC Done.




DATE: 23/1/2012

SYSTEM: Thermal Oxidiser LEADER: Dean Shewring



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

No further action required Refer to action #24

Done


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

No further action required Done


Buildup of slag in bottom of TO

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

No further action required An access hatch will be provided on the thermal oxidiser inlet ducting to allow confine space entry to inspect the thermal oxidiser as required.

KC Done

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





DATE: 23/1/2012




SAFEGUARDS



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

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

No further action required - Done


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

No further action required Part of Plant SOPs to include TO shell temperature measurement as part of field operator’s routine duties

LK Done

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


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





DATE: 23/1/2012




SAFEGUARDS


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



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 SV-1040 set to FO on the P&ID.

KC SV-1040 confirmed as FO

– see relevant ITR


Rapid quenching does not occur

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

No further action required

KC/RM Done


False low temperature reading at the ECC 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 Low temp alarm will be installed.

RM Done


Dilution air damper open when it should not be

Nothing unsafe just a change in plant pressure

Will be detected through plant pressure controls


KC Done




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 After further review dilution damper position optimised for plant ductwork layout.

KC Done


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 to plant and personnel

No further action required - NA




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

KC Done

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

No further action required Include nozzle inspection and testing as part of scheduled maintenance

LK Included in SOP.

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 Done during commissioning.

RM Pulse volume confirmed as sufficient during clean soil commissioning.


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. Bindicator Added to P&ID

No further action required KC Done


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

No further action required High level alarm will be indicating the accumulation of dust in the bag house hopper.

TT/RM- Done

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. (This is a programming requirement)

No further action required RM Done




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.( It is required to ensure that epoxy coating is applied to baghouse parts in contact with process stream)

No further action required KC Done




DATE: 23/1/2012

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

LEADER: Dean Shewring



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 Need noise study feedback.

POD Noise monitoring during operation has been within

limits at monitoring points.




DATE: 23/1/2012

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




SAFEGUARDS


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) Will be incorporated.

KC Done

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 Under way



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

No further action required (Include scrubber pump backup as part of emergency power users.)

RM Done


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) Control logic is being further reviewed.

RM Done.


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 Done


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

Sump pump and bund will be shown on P&ID.

KC Done.





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 2

nd level detector will be added to

P&ID.

KC Done


Solenoid valve to the demister sprays is stuck closed

Build up 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) This will be manually controlled as needed from the control room by plant operator.

RM Done

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 This will be incorporated into the P&ID by EPS

KC/TT Done



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

DATE: 27/1/2012

SYSTEM: Scrubber Recycle LEADER: Dean Shewring



SAFEGUARDS



Scrubber recycle pump failure

Plant shuts down (accepted response)

Manual changeover of pumps

No further action required Include onscreen alarm to alert operator of pump failure

RM To be included


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

Operator regular inspection and maintenance as required

No further action required Tai to ensure the inspection of pump seals is part of field operator’s routine checklist. SOPS

TT Seal checks included on shift check list.


Overdosing caustic High pH – no significant consequences identified

pH meter will alarm high pH

No further action required Rudy to include onscreen alarm to alert operator of high pH

RM Included


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

No further action required Tai to ensure the independent checking of scrubber liquid pH is part of field operator’s routine checklist. SOPS

TT Calibration is done daily. SOP includes

use of pH strip to check.


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





DATE: 27/1/2012




SAFEGUARDS



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

Correct packing selection SS packing will be used.

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

KC Done


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 SOPS to include check on valve & no change on pH or conductivity.

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

RM/TT Done

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. Check valve is included in P&ID

Done


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

No further action required KC/LK NA




DATE: 27/1/2012




SAFEGUARDS


81. Impurities Iron oxide dust not collected in baghouse

Blockage in the scrubber

Operator checks for water discolouration

No further action required Include in SOPs

TT Colour assessment (against clear) is part

of daily checks.

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

Solids build up in system

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

Change made, primary blow down will be automated based on conductivity. P&ID will be amended, manual bypass will be included.

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

RM Done

83. Testing High flow when taking samples

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


TT/LK NA




DATE: 27/1/2012

SYSTEM: Liquid Feeds to Pugmill LEADER: Dean Shewring

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

MINUTES BY: Peter O’Dea


SAFEGUARDS



Pump requires maintenance

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

Drain valves have been added to P&ID’s

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

KC Done.


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

FCV-1019 valve changed to electric valve with spring return

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

RM Done.


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

NA




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 A

MINUTES BY: Peter O’Dea


SAFEGUARDS



Rock, metal piece, etc gets into the pugmill

Pugmill drive overloads and equipment damage

High current detected shutting down the pugmill Potential for such events will be mitigated via soil management

No further action required Rudy to include this shutdown interlock

RM Done.


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. Refer to Item #22



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 It will be incorporated.

RM Done.


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 Part of OH&S plan

LK DTD plant operations SWMS covers hot

surfaces. Hot surface warning signs

installed.




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



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



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 Add PI to PCV1082 valve.

KC NA


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)





DATE: 27/1/12




SAFEGUARDS



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

Potential to cause injury to personnel

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

No further action required Ensure that he stated action is carried out in the field

KC Done




DATE: 27/1/12




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 Done


Stormwater falling into the bunded area

Stormwater management required

Bunded area, sump, discharge to water treatment plant





DATE: 27/1/12




SAFEGUARDS



Pipe breakage, e.g. mechanical impact

Caustic leak with the potential to harm personnel

Strong materials of construction for the proposed tubing SS pipe to be used as outer protection over Teflon tubing at site installation.

Ensure that the small bore caustic piping is adequately protected from mechanical impact Ensure the P&IDs are drawn to reflect this double jacketed arrangement

KC Done


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

No further action required Careful review to ensure proper internal pressure relief

KC NA

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: 27/1/12




SAFEGUARDS


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

No further action required TT to include this activity as part of SOPs

TT NA


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 P&ID has been amended to show this change.

TT Done

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

TT/KC Done

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 Doner



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

DATE: 26/6/12

SYSTEM: Towns Water Tank LEADER: Dean Shewring

DRAWING: C143-PF-96D-DTDU-10009 Rev B MINUTES BY: Peter O’Dea


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 Done


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 Done


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 Done.




DATE: 26/6/12




SAFEGUARDS



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 Done


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 Level indication alarm on TW tank goes to DTDU


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

TT/LK Done

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 LCV type has been changed to pressure pad which will be installed near bottom of TWT

LK Done




DATE: 26/6/12




SAFEGUARDS


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 LCV type has been changed to pressure pad which will be installed near bottom of TWT

LK Done

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) LCV type has been changed to pressure pad which will be installed near bottom of TWT

LK Done




DATE: 26/6/12




SAFEGUARDS


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. Manual isolation valves added.

LK Done




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 NA


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

TT Done




DATE: 26/6/12




SAFEGUARDS



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

TT Done


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

No further action required Rudy/Keith to ensure this option is made available either in hardware of onscreen

RM/KC Done


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. Redundant pump inlet line at the mains water supply tank with its own strainer is provided to minimise interruption of water supply to process equipment

No further action required LK NA


Loss of water to the ECU

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

Nozzles are made from appropriate SS materials

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

TT Done




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 in the water tank and piping.

Check valves in supply line. MOC document prepared by TT & KC MOC suitability to be determined during FAT

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

TT Done

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, and the use of check valves

No further action required TT need to check proper material selection and check valve

TT Done

127. Plant Items Acidic vapours, etc throughout the plant

Corrosion of equipment as above

MOC document prepared by TT & KC MOC suitability to be determined during FAT

Review the materials of construction for all equipment throughout the plant

TT Done

128. Electrical Power failure Loss of critical equipment

Emergency generator Final review by BK/TT

Confirm the required items connected to the emergency power supply

TT/BK Done




DATE: 26/6/12

SYSTEM: Instrument and Compressed Air LEADER: Dean Shewring



SAFEGUARDS



Add a connection point for temporary rental compressor for back up.

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

KC Done


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

KC Done


P&ID will be amended to reflect the requirements.

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

KC Done




DATE: 26/6/12




SAFEGUARDS



Compressor will be sized for duty.

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

RM Done


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

KC Done


PCV-1079A will be eliminated

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

KC Done




DATE: 26/6/12




SAFEGUARDS



Not applicable, further assessment determined dry air only required for instrumentation.

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

KC NA


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

ECU nozzle and BH pulse valves will with stand full comp. Pressure. Pressure rating of instruments to be advised by KC

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

KC Except for 2 non-critical valves, valves confirmed by supplier

as fully rated.


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

Compressor package chosen by CS will have pressure relief safety valve.

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)

KC Done




DATE: 26/6/12




SAFEGUARDS



Heat from 10 bar pressure requirement

Potential high temperature damage to the downstream equipment

Compressor package is delivered with HX cooler.

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

TT Done – see Action 131




DATE: 26/6/12

SYSTEM: OVERVIEW LEADER: Dean Shewring

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


SAFEGUARDS


140. Commissioning P&ID’s will denote that high point and low point vents will be required as part of piping installation.

Provide high point vents and low point drains for hydro testing once the piping layout drawings are known Final piping will be field fitted. Vent and drain points will be identified at that time.

KC Done

141. Commissioning Foreign objects in the pipes during commissioning

Potential to damage equipment

Sensitive inline equipment to be removed during flushing operation. To be detailed in commissioning plan.

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

RM/KC Done

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, RM, KC, BK

Done

143. Commissioning RM/TT/KC to have dedicated review to determine best sampling locations.

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

KC/TT/RM

Further ports installed during burner tuning –

deemed sufficient quantity subsequent

to the tuning.




DATE: 26/6/12

SYSTEM: OVERVIEW LEADER: Dean Shewring

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


SAFEGUARDS


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 Done



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



Will amend P&ID as required

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

KC Done

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

KC to confirm with compressor vendor.

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 Done


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

KC to confirm with compressor vendor.

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 Done




DATE: 19/10/12





SAFEGUARDS


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

Condensate will form and build-up within the air receiver

Manual draining Automatic condensate valve will be added.

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

KC Done




DATE: 19/10/12





SAFEGUARDS



P&ID will be amended to reflect this change

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 Done




DATE: 19/10/12





SAFEGUARDS



Need to balance flow to pugmill sprays

P&ID will be amended to reflect this change

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

KC Done


P&ID correction To be amended. P&ID page #1009

Show PCV1052 controlling upstream pressure as this valve is used for deadhead protection for the pumps

KC Done



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 Done



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 Done – refer Action 85




DATE: 19/10/12





SAFEGUARDS




Provide an isolation valve on PI 1019B (consistent with all PIs)

KC Done



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 Done


Spray nozzle unwinding and falling off

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

Will be done as per recommendation. KC

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

KC Done


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

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

Control logic will be prepared as per recommendation. To be amended. P&ID page #1003

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

RM Done


Note that the scrubber blowdown is approximately 80 deg C

Potential for burn injuries if personnel contact hot surfaces

Direct bleed scrubber blow down to a safe location.

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

LK Scrubber blowdown is directed into closest sump.




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)

MINUTES BY: Bala Kathiravelu


SAFEGUARDS


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

- NA


PROJECT: Orica Villawood Water Treatment Plant

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

DATE: 29/11/12 Revised: 22/03/13

SYSTEM: High Capacity Settling Tank LEADER: Dean Shewring

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


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 Done


Mark up the P&IDs to show all line sizes, e.g. the clarified water line from the settling tank. NOTE: Upon further consideration, it was decided that main process line labels would be sufficient.

PA Done


Delete the additional diaphragm valve downstream of the High Capacity Settling Tank gate valves. The gate valves are at ground level (i.e. accessible) and can be used for isolation for pump flushing etc instead – This section of HB50 has been deleted.

PA Done


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. Note: Chemical dosing systems are not able to be located within IBC bunded areas due to size. However, they are located within concrete bunds, therefore no environmental consequence or overflow to permeable ground will occur.

PA Done


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 Done

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). Air break installed in new mixing funnel design.

PA Done




DATE: 29/11/12 Revised: 22/03/13



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. – Sedimentation Transfer pump system deleted for HB50. Therefore no need for PRV. For FB50 sedimentation pump, place half inch spill back loop with a union to allow the potential install of a reducer/orifice plate to reduce flow f too much sludge is being bypassed through the bleed line. Bleed (half inch) line to Flocculation tank.

PA Done

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. – Sludge lines from HB50 have been deleted.

PA Done

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). UPVC used for process lines. Valves have viton seals, therefore are considered very low risk of sticking.

PA Done




DATE: 29/11/12 Revised: 22/03/13



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. – Sludge pump has been deleted on HB50.Sedimentation tank high level alarm will notify operator of high level in sedimentation tanks. Timer deleted as possible scenarios exist where timed pumping will still cause overflow.

PA Done

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. Long process lines have air relief valves, however short process lines are considered low risk of overpressure and will not have relief valves. PN12 piping used, which is pressure piping.

PA Done

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). Sediment transfer line from HB50 have been deleted.

PA Done

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 Done




DATE: 29/11/12 Revised: 22/03/13



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 Done





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 Done


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. Pump well sumps are connected and considered to provide sufficient capacity to contain spills.

LK Done


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. Automation of break tank recycle will not be undertaken. Instead SOPs to include procedure to ensure that zeolite fouling does not occur.

PA Done

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 Done





DATE: 29/11/12

SYSTEM: Feed Tank System including the Untreated Water Basin


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



SAFEGUARDS


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 Done





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). Dual chambers have been deleted. Improved single mixing chamber used instead, and therefore short-circuiting unlikely.

PA Done


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

PA Done


Show both isolation valves on the outlet of flocculation chamber 2 from the flocculation tank – single Flocculation chamber selected.

PA Done


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 Done


Loss of containment of flocculant

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

PA Done





DATE: 29/11/12

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


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


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. Air break is installed between flocculant discharge and water level.

PA Done


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 Done

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 Done

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 Done





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 Done





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. Break tank has been removed.

PA Done


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. Vessels are rated at higher than pumps can generate. Additionally, high pressure switch is installed to cut out pumps during high pressure scenario.

PA Done

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 Done





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 Done


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 Done

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. Flow switch has been deleted.

PA Done





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 Done


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 Done


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 Done


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 GAC purifiers

SA Done





DATE: 29/11/12





SAFEGUARDS



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. Air release valve has been installed to prevent vacuum generation. Air relief valve must be installed in bunded area in case of leakage.

PA Done

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. Vessel inspection completed, and PRVs required to be replaced.

LK Done

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 Done

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 Done





DATE: 29/11/12





SAFEGUARDS


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

PA Done

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 Done




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 Done


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

PA Done





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 Done


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 Done

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. Air relief valve to be installed downstream of valve to prevent significant vacuum being pulled.

SA Done





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 Done


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

PA Done


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. Line from high capacity settler (HB50) has been deleted.

PA Done


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 Done





DATE: 30/11/12

SYSTEM: Sedimentation Tanks LEADER: Dean Shewring



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 Done





DATE: 30/11/12


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. – Process water will be returned to Untreated Water Storage Pond during Commissioning Also, avoid using detergents / dispersants when cleaning. These can cause future issues with the settling processes

LK Done

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 Done


Guide Words Used in this Study: Line-by-line guide words: 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

Documents

PINNACLE RISK MANAGEMENT PTY LTD - HAZOP STUDY …