PERTH SEAWATER DESALINATION PLANT, FIVE YEARS, 200GL, … · 2018. 11. 15. · • Implementation...

Wor World Congress/Perth Convention and Exhibition Centre (PCEC), Perth, Western Australia September 4-9, 2011 REF: IDAWC/PER11-286

PERTH SEAWATER DESALINATION PLANT, FIVE YEARS, 200GL, AUSTRALIA’S OPERATIONS AND MAINTENANCE BENCHMARK

Authors: Sjoerd Sibma, Greig Mercer Presenter: Sjoerd Sibma

Desalination Manager, Water Corporation of Western Australia

Abstract

The Perth Seawater Desalination Plant (PSDP) has been strongly influenced by the stakeholder needs during design and construction and then into operations. The key drivers have included the following:

• Water demand due to drying climate and on going drought conditions • Tough Environmental constraints related to existing environmental conditions in the source

water of Cockburn Sound • Energy Usage, minimising Consumption and using alternative energy sources

Against this background the proAlliance team at PSDP has effectively managed the risks and constraints in place to deliver a benchmark performance for the desalination industry: o 200GL production o Plant availability increased to greater than 98% o 1950 days worked without Lost Time injury o No environmental or quality breaches o ISO accreditation in Safety, Environment and Quality It is the purpose of this paper to illustrate how the PSDP operations team has managed to achieve sustainable operations over the past five years. In doing so, they have achieved acclaim for their operating excellence in both Australia and internationally and the lessons learnt at PSDP have been adopted by the next generation desalination plants commissioned since 2007. By adopting a “Best for Project” approach the alliance team have balanced parent company drivers, cultural differences, risk management, dispute resolution, workforce expectations and gain share management to achieve sound commercial and sustainability outcomes for the alliance partners.

IDA World Congress – Perth Convention and Exhibition Centre (PCEC), Perth, Western Australia September 4-9, 2011

REF: IDAWC/PER11-286 -2-

I BACKGROUND Perth has experienced significant reduction in the stream flow into the Perth Metro Storage Dams over the last century. This situation has continued to worsen and is clearly illustrated in Figure 1 below. Against this background the decision was made in 2000 to proceed with the construction of a seawater desalination plant and after a brief delay the Perth Seawater Desalination Plant project was agreed in April 2005, first water delivered in November 2006 and Project Completion achieved in July 2007. Against this background of a drying climate and increasing population the direct impact on the Perth Metro Storage Dams is clearly seen in Figure 2 below. PSDP has quickly become an integral part of the Water Corporations Integrated Water Supply System and is being called on to maximise production year after year in order to assist in meeting the water demand of Perth. To meet this call to maximise production the PSDP team has responded effectively and this has resulted in the impressive Operational, Safety and Environmental record over the life of the project: o 200GL production o Plant availability increased to greater than 98% o 1950 days worked without Lost Time injury o No environmental or quality breaches o ISO accreditation in Safety, Environment and Quality

Figure 1: Stream flow into Perth Integrated Water Supply System



Figure 2: Perth Metro Dam levels – 2004 to 2011



II INTRODUCTION In November 2006 the 45GL per year PSDP was commissioned in Naval Base, Perth, producing 17% of Perth’s annual drinking water supply requirements. The Plant is managed under the proAlliance 25 year “Operations & Maintenance Alliance Agreement” between the Water Corporation of Western Australia and Degremont Pty Ltd.

Figure 3: Aerial view of Perth Seawater Desalination plant. PSDP has delivered 200GL of drinking water into the Corporations Integrated Water Supply Scheme since November 2006, initially in cooperation with the constructors, then through the defects correction period into full Operation and Maintenance (O&M) including Asset Replacement. This achievement was made within the proAlliance framework, implemented by Degremont under the leadership of the Alliance Management Team, and presented below as follows: • Alliance Environment • Quality, Safety and Environmental Management • Operation and Maintenance • Asset Replacement and Improvement • Plant Manning • Conclusion



III ALLIANCE ENVIRONMENT The O&M Alliance agreement for PSDP incorporates the following principles: • Balance between Governance and Technical environment. • Alliance transactions are open book with a high level of transparency and sharing. • While Degremont is responsible for the day to day management of plant operation and maintenance,

the alliance incorporates the following shared actions: • Procurement of energy and chemicals through the Water Corporation • Traineeships through the Water Corporation and Degremont • Technical Support and R&D through the Water Corporation and Degremont

• The alliance financial mechanism calls on the Water Corporation to pay actual costs for the agreed

annual production. • An annual direct cost target is used to judge performance across the 3 key operational areas of Plant

Availability, Plant Performance and Asset Management. • Any savings or cost overruns against the direct cost target are shared between the Water Corporation

and Degremont through the Risk and Reward gain share mechanism. • The following Alliance principles form the backbone of the agreement:

• Safety is the Participants’ first priority. • Good Faith. • Commitment to achieving outstanding business outcomes whereby all Participants either win or

lose together. Win lose is not an acceptable business outcome and the Participants agree to share the gain of exceptional performance or the pain of poor performance.

• Accountability for the actions of the people managed and the results achieved. • One fully integrated team, using a single set of management systems. • All actions and decisions are to be “Best for Project”. • All transactions are fully open book. • Encouragement of innovative thinking. • Honest and open communication with a transparent agenda. • Rigorous debates encouraged and managed.

• These principles have been embraced by the proAlliance participants and summarised in the O&M

team as follows: • Our team, one team • Respect • Trust • Walk the talk • Resolve conflicts immediately • Share problems

Against this alliance background the operation and maintenance of the PSDP has been able to flourish without the complex constraints which seem to be inherent in the more complex legal frameworks associated with PPP projects.

Wor World Congress/Perth Convention and Exhibition Centre (PCEC), Perth, Western Australia September 4-9, 2011 REF: IDAWC/PER11-286

IV QUALITY, SAFETY & ENVIRONMENTAL MANAGEMENT Degremont has employed its quality management system to provide a working platform for the management of quality, safety and environment at PSDP. Degremont’s OMEGA management system implemented through an online tool focusing on risk management across the full spectrum of plant management and includes: • Risk management • Operational quality • Safety • Environment • Incident management • Human resources • Plant Operation The risk focus has resulted in early detection of any weaknesses and preventative actions being implemented to address these, resulting in the impressive record of the last 5 years of operation. The tools used to mange quality include an online document control system, computerised maintenance management tool, SCADA / HMI system, reporting tool, financial tool, Business Improvement and Risk Assessment, and Project management tool. These are used by the Operations team to identify risks through both systems and team inputs, assess the risks and drive the solutions to achieve a best for project “improved” outcome. IV.1 Safety PSDP has achieved a clean safety record since the operations team was created in 2006, now having achieved 1950 days without a single Lost time Injury. This is a good achievement as activities have not been limited to operations but have also included defects correction, asset replacement and implementation of many improvement projects.

Figure 4: SCADA control



IV.2 Environmental Management Located on the semi enclosed Cockburn Sound, the Environmental License for the operation of the PSDP contains very particular constraints on the operation of the plant during low Dissolved Oxygen occurrences in Cockburn Sound. The waters of Cockburn Sound are subject to large fluctuations in dissolved oxygen levels in the deeper channels depending on the available wind mixing energy. Traditionally during the autumn and spring calm weather periods result in stratification of the waters and dissolved oxygen levels in the deeper channels (20m) drops below desirable levels. As a precaution against the possibility that the diffused brine effluent stream may adversely impact on dissolved oxygen levels during these naturally occurring calm weather periods, various operating constraints were applied to the operating license of PSDP: • Real-time monitoring of dissolved oxygen, salinity, temperature, currents and winds is made via 3

monitoring buoys located in the sound. This monitoring data and Meteorological forecasting is integrated into a predictive warning system.

• If a low dissolved oxygen event occurs a manual monitoring program is triggered (previously the plant would also reduce to 1/6th

This has resulted in up to four weeks lost production over the operating period. Despite these operating constraints PSDP has operated without any environmental incidents during its 5 years of operation.

production during a low dissolved oxygen event; recently modified to monitoring only)

•

Perth Seawater Desalination Plant

Figure 5: Cockburn Sound protected by Garden Island to the west



V PLANT OPERATIONAL & MAINTENANCE CHALLENGES The challenge of maximising production at PSDP has been taken on board by the production team and has been addressed through a number of activities:

• Maximise daily production and bank water through optimisation of process areas. • Implementation of Bromide Operation • Maximise plant availability through rigorous maintenance. • Reduce shutdown periods to a minimum through rigorous planning of maintenance and

shutdown activities This has resulted in an increase in production on an annual basis, with production of 10% more than target achieved in financial year 2011. V.1 Plant Operation and maximisation of production This has been achieved through regular reviews of operational performance and risk assessments of plant operability and the strategy has been to focus on the key operational, process and maintenance activities which assure plant production, availability and water quality, all essential components of maximising production on a sustainable basis. These include the following: • Optimisation of process areas to ensure that plant capacity and availability is not compromised:

o Monitoring of seawater quality and pre-treatment performance through the seasons has given an understanding of the risks to process which has been incorporated into the operation of the pre-treatment and the improvement of process control to ensure full production capacity despite varying water quality conditions. This is an on going process and will continue through the duration of the project.

o Membrane management includes performance monitoring, routine maintenance flushing and planned membrane cleaning to ensure that membrane aging is controlled and optimised to maximise the production capacity and permeate quality over time. Into the future this will also include the decision process for membrane replacement.

o Optimisation of post-treatment remineralisation, disinfection and fluoridation has been an important operational activity to ensure that the permeate produced by the RO plant meets the drinking water quality specification and is ready to export to the IWSS. By evaluating performance of the post treatment process a number of improvements have been made to the dosing and process control systems.

o Bromide Operation – after a few years of operation a review was made of the impact of Bromide in PSDP export water on the IWSS. Through the alliance with the Water Corporation the decision was made to modify the specification from 0.1 mg/l to 0.2mg/l in order to maximise production. This resulted in a gain of approximately 3% production and 6% energy saving since implementation in mid 2009.

V.2 Plant Maintenance and Availability As a bulk supply source intended to top up existing water sources the PSDP was constructed with no redundancy of primary equipment. In order to meet the objective to maximise production the availability of all equipment has been a prime focus of the maintenance team activities. In order to meet PSDP maintenance objectives 21 shutdown days are scheduled into the annual production planning while an additional 20 Water Corporation shutdown days are scheduled for IWSS activities. This gives the possibility of shutting down for 41 days per annum; obviously the reduction of



shutdown activities, without compromising maintenance activities, provides an important opportunity to produce additional water. In order to meet this challenge the maintenance strategy has had to be shaped to meet the demands: o Schedule planned maintenance and performance monitoring on a regular basis minimise breakdowns

and ensure equipment availability. Through the computerised asset management system (CAMS) regular maintenance is programmed into the weekly operational rack flushing and chemical cleaning shutdowns to optimise availability.

o PSDP and IWSS shutdown activities are overlapped as much as possible to reduce shutdown duration.

o Condition and performance monitoring of key assets (electrical, pumps, ERD, GRP, membranes, structures) is undertaken regularly in order to anticipate any deterioration or potential failure of equipment and schedule the downtime into planned shutdowns.

o Hold spares for critical equipment, including rotable spares, to minimise equipment downtime in the event of breakdowns or planned activities

o Constantly review operational and maintenance findings and engineer out weaknesses through improvement projects

Through the implementation of these actions over the 5 years of operation a consistent increase in plant availability has been achieved: • Current plant availability of greater than 98% (excludes planned shutdowns) • Shutdown periods for cleaning and inspections reduced significantly, result is these activities are no

longer critic path items during shutdowns.

Figure 6: Removal of energy recovery device for maintenance.



VI Plant Performance

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Monthly Production Cumulative Production Energy Consumption Target Energy Consumption

Figure 7: The graph above illustrates the key production performance parameters of the plant: VI.1 Production The monthly production illustrated above tells the story of PSDP’ 5 year history:

• 2007 - After the initial ramping up of production in early 2007 there were a few months of reduced production as a result of defect correction activity before the 1 year electrical inspection shutdown.

• 2008 – The year started with production limited by coiling coil failures on HP pumps, but this was soon replaced with various shutdowns from April through to July caused initially by lack of wind mixing in Cockburn Sound (resulting in low dissolved oxygen) and then a voluntary shutdown during a Western Australian energy crisis.

• 2009 – Solid production except for a maintenance shutdown mid year. • 2010 – Solid production except for maintenance shutdown mid year • 2011 – Solid production and only a limited shutdown in February, major electrical maintenance

shutdown planned for late 2011 / early 2012. Increased average daily production above the nominal plant capacity has been achieved through optimisation of plant operation and maintenance activities (approx. 6%) and the introduction of Bromide Operation (approx. 3%) which revised the bromide target in the treated water from 0.1 to 0.2 mg/l, resulting in reduction in second pass pump operation.



VI.2 Energy Consumption Energy efficiency has been maintained across the period by continuously monitoring energy efficiency of key equipment and rebuilding as required. To date only the Treated Water Pumps have been rebuilt (wear rings replaced with alternative compound) and the HP pumps will be inspected and if necessary overhauled in late 2011. Other improvements in energy efficiency have been achieved through:

• Bromide Operation - revision of the bromide target in the treated water from 0.1 to 0.2 mg/l has resulted in a reduction in the number of second pass pump in operation. This gives approximately 6% energy saving.

• Second pass pump operation – improvement to the control philosophy of second pass pumps has resulted in more stable conductivity / bromide levels in the permeate giving an additional 1% energy saving.

VI.3 Water Quality Water Quality has been managed to ensure that treated water meets the contractual targets. A number of key performance areas have been identified through annual risk assessments and managed to achieve the best project solutions: Seawater quality – as seawater is abstracted from the semi protected Cockburn Sound large variations in seawater temperature and organic loading is experienced. This results in high levels of bio fouling during summer months and shock chlorination and pre-treatment dosing is adjusted to optimise quality of the filtered water. RO permeate – monitoring of permeate quality is made routinely and if necessary maintenance is performed on membranes and pressure vessels to ensure membrane integrity and guarantee permeate conductivity. Premature failure of membrane adaptors (suspected defective batch of membrane adaptors) has resulted in an extensive replacement project being completed in early 2011. Post treatment – during winter periods flow rates of 10% above design capacity are possible (especially since Bromide Operation has been introduced). The lime and CO2 dosing system was not able to operate effectively at these high flow rates and a number of improvements were made to ensure that the alkalinity target was achieved. These improvements included:

• Addition of polymer treatment to lime saturator feed water to guarantee settling performance of the lime saturator.

• Increase in lime dry feeder capacity to dose additional lime to meet alkalinity target at higher flow

• Improvement in CO2 injection system to ensure saturation at higher dose rate. • Improvement in process control system to improve stability across the increased dose rates.

Disinfection of treated water is achieved through dosing of chlorine gas at 0.8mg/l, while Fluoride is dosed at 0.85mg/l as per regulatory requirements. The management of water quality has ensured that PSDP water quality has always met IWSS requirements and been accepted into the water supply system.



VII Asset Replacement and Improvement Projects The overall philosophy that has been adopted for delivery of asset replacement and plant improvement projects has been one of re-engineering to improve performance rather than replacing “like for like”. This has resulted in improvements to plant operability, availability and even a reduction in shutdown requirements. A project management tool has been introduced to guide the project owners (usually members of the operations team) through the process of change management, project evaluation and project delivery. Examples of key projects delivered are as follows: • Seawater Inlet screen improvement – corrosion of the support structure retaining bolts after 3 years

of operation posed a risk screens coming loose and possible entrainment of a large sea mammal. The solution was to replace all susceptible SS with a support structure fabricated from HDPE, thus avoiding any chance of further corrosion.

• Band screen mussel removal system – the as-built band screen installation had limited capacity to process mussel shells. Any occurrences of large quantities of mussel shells after shock chlorination or plant shutdowns resulted in mussels backing up in discharge channels and band screens and potential damage to the rotating band screens. The installation was modified to include a separator and screw conveyor which separated mussel shells from the wash water stream thus avoiding any backing up in the discharge channels

• Seawater recirculation manifold – any prolonged shutdown of the intake pipe resulted in a deterioration of water quality which prevented divers from working in the pipe and resulted in increased loading of the pre-treatment filters at plant startup. To avoid this occurrence a recirculation manifold between intake and outfall was installed which allows a low volume, safe circulation of water through the intake pipe and sump keeping the water fresh and clean.

• Seawater Pump improvement – having suffered several failures of non drive end bearings on these vertically mounted split case pumps, two problems were identified and solutions implemented. The first involved improving the locking of the thrust bearing to the shaft to avoid the shaft dropping. A solution was proposed by the site maintenance team, agreed by the pump manufacturer and implemented. The second involved replacing the non thrust end bearing with an enclosed rubber cutlass bearing thus avoiding any seal and corrosion issues. No further bearing problems have occurred.

• High pressure pump motor cooling coils – multiple failures of all cooling coils on the motors driving the high pressure pumps occurred early in the defects period as a result of corrosion and erosion due to poor calibration of cooling flows through the heat exchangers on the motor / pump skids. The supplier proposed to replace with identical, the alliance made the decision to upgrade to titanium coolers and no further cooler issues have occurred.

• Cleaning in Place chemical handling system – the original CIP system involved an unreasonable amount of manual handling of cleaning chemicals (both DG and non DG). A dedicated bunded load-in, storage and automated transfer facility has been installed. This has resulted in reduction of operating hazards and increased plant availability as cleaning and flushing sequences are automated and manual intervention minimised.

• Increasing capacity of re-mineralisation system – the remineralisation system was designed to operate at design maximum of 140 MLD, but the plant has been operated up to 155 MLD resulting in insufficient lime dosing, CO2 coming out of solution and extremely erratic performance. Key improvements were identified and implemented and today the plant can comfortably meet its alkalinity and LSI targets even at maximum flow



VIII Plant Manning The original manning and skill requirements have evolved over the operational contract which commenced in 2006. It soon became apparent that the day to day operations of this major desalination facility required some fine tuning to manning in order to deliver the desired business outcomes for the alliance partners. In order to meet the demands being placed on the plant of maximising production it became apparent that additional skills were required to manage the critical demands identified during risk assessments: o Purchasing and storage of critical spares – as a high percentage of RO spares are imported high

specification items, with long lead times a post was created for a specialist purchasing and stores coordinator.

o Project management – to manage the defects correction projects identified during the Defects Correction Period and to then continue into the asset replacement and improvement project phase (in line with the improve rather than replicate strategy) a project manager was included in the team to manage the implementation and delivery of projects.

o Planning and scheduling – in order to optimise plant availability the need to reinforce the management of maintenance and shutdown scheduling on a day to day basis was identified as a key skill and the position filled.

o Corrosion / durability management – technician recruited as reliable contractor services proved difficult to source cost effectively.

o Standby Operator – an additional standby operator was added to the team to ensure that full cover was available during leave, training and sickness.

These additional posts have been funded from savings against the proAlliance targets and ensure that the high demands placed on the operations and maintenance team to operate the plant at maximum production is sustainable. Current Manning Levels are summarised as follows:

• Plant Management – 4 • Asset Management – Maintenance and Replacement - 9 • Finance and Administration – 1 • Operations and Process – 7 • Trainees - 2



IX Conclusion By adopting a “Best for Project” approach the proAlliance team has successfully balanced parent company drivers, cultural differences, risk management, dispute resolution, workforce expectations and gain share management to achieve sound commercial and sustainable outcomes for the alliance partners. In doing so, they have achieved acclaim for their operating excellence in both Australia and internationally and the lessons learnt at PSDP have been adopted by the next generation desalination plants developed in Australia (Victoria Desalination Project and Southern Seawater Desalination Plant). This success can be attributed to the following key drivers: • Alliance contract focused on delivering a good work environment and great results • Alliance Leadership team who have encouraged innovation and optimisation. • Dedicated team who have worked hands on to optimise operation & maintenance to maximise

production • Dedicated change management to ensure that all problems are turned into an opportunity to improve

the plant performance. • Focus of the proAlliance team to meet the water demand needs of the IWSS during this period of

critical water demand. The successful operation is highlighted in the following achievements: • 200GL production • Energy efficiency maintained at below 3.5 KWH/m3 (10% below target) • Plant availability increased to greater than 98% • Actual costs average 8% below target resulting in savings to the alliance partners • 1950 days worked without Lost Time injury • No environmental or quality breaches • ISO accreditation in Safety, Environment and Quality Against this background the proAlliance team remains committed to ensure successful operation well into the future by adopting the following strategies: • Continuous Improvement philosophy to be followed. • 2nd

• Feasibility study proposed to investigate possibility of 10% production gain. Five year plan developed.

• Membrane replacement strategy to be implemented. • Continue improvement of people skills.

PERTH SEAWATER DESALINATION PLANT, FIVE YEARS, 200GL, … · 2018. 11. 15. · • Implementation...

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