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A Selection of Plexus Water & Energy Projects
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South Tarawa Water Supply Project (STWS), Kiribati for Asian Development Bank

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The South Tarawa Water Supply Project (STWSP) will address factors which result in the high incidence of waterborne disease in South Tarawa, the capital of Kiribati, through the delivery and effective management of new and rehabilitated climate-resilient water supply assets and improved hygiene practices. Kiribati’s capital, South Tarawa, has a population of around 56,000.

South Tarawa has a reticulated water supply system which covers about two-thirds of its population and is operated by the Public Utilities Board (PUB). Water supplied by PUB is rationed to 2 hours in every 48 hours due to insufficient supplies and high physical losses from the distribution network. Projected population growth means that, without intervention, the gap between supply and demand will continue to widen.  

Plexus will provide Construction Monitoring, Commissioning & Performance Acceptance Testing support services during installation of the water infrastructure and have delivered the following outcomes for the project to date:

  • Market Sounding Report on preferred delivery methodology and contracting strategy for 12MLD of seawater desalination infrastructure, plus18 water supply zones, 18 pump stations and tanks, 180 km of HDPE pipelines;

  • Technical Specification for containerised desalination plants;

  • Technical Specification for an Optional Purpose-Built desalination facility

North Adelaide Irrigation Scheme (NAIS) for South Australia Water

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The NAIS project involves using recycled water to expand high-value crop production on the Northern Adelaide Plains. A key goal of the scheme is to develop a sustainable, long term, economic benefit to the state of South Australia through the use of this recycled water.

PWE was contracted to provide Mechanical, Pump Station, Surge Analysis and Pipeline Design Leads and Review Services for a scheme which will deliver 12 gigalitres (GL) a year of high quality recycled water for high-value irrigation from the Bolivar Wastewater Treatment Plant via a 28km pipeline.

Plexus provided the following resources for feasibility and detailed design:

  • Design management;

  • Mechanical Lead;

  • Pump Station/Surge/Pipeline Lead;

  • Peer Review Services – mechanical and process

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Murchison Towns Nitrate Removal for Water Corporation WA

​The regional towns of Cue, Meekatharra, Mount Magnet & Sandstone have an issue with naturally occuring high levels of nitrate in their groundwater source which poses certain risk for infants under 3 months of age.  

PWE was appointed to:

  • Investigate four different treatment options - Reverse Osmosis, Electrodialysis Reversal, Ion Exchange, Microvi biological treatment

  • Produce a concept design report (CDR), which investigated the four potential treatment option in terms of technical suitability, reliability, cost and the ability to be operated remotely with minimal site attendance

  • Select a recommended technology

  • Develop an Engineering Summary Report (ESR) with greater accuracy in engineering design and budget for construction plus long-term operation of the four plants.

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Mt Holland ZLD WTP Project

Mt Holland is a lithium mine in the Goldfields Region of remote Western Australia some 500km East of Perth. Mine site water requirements, including human consumption and process water around the mine site, will largely be met by groundwater abstraction and treatment to Australian Drinking Water Guidelines (ADWG). 

Groundwater quality in the borefield is hypersaline, with an average total dissolved solids (TDS)  of 95,000 mg/L. 

PWE undertook to:

  • Investigate available treatment technologies to

  • treat the broad range of water quality available.

  • Technologies included:

    • Reverse Osmosis

    • Evaporative Technology

    • Humidification/Dehumidification

    • Eutectic Freeze Crystallisation

 

  • Identify and recommend the preferred desalination method based on technology risk, practicality of installation and operation, plus associated life-cycle cost of the complete system (to Zero Liquid Discharge level)

  • Identify preferred vendors 

  • Prepare Technical Specification for inclusion in formal RFQ

  • Assist in assessment of tenders & contract negotiations

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Turkmenistan (2016_10_08 23_05_46 UTC) (

Turkmenistan Desalination Project

​PWE, together with its project partners, was asked to develop and deliver a feasibility study for a 260ML/d desalination plant plus pumping infrastructure and a 330km pipeline to treat brackish water from the Caspian Sea for irrigation and human consumption and convey it to an area in the Kara Kum desert in central Turkmenistan.

PWE undertook a number of risk assessment workshops during the early stages of the  Study involving senior design, construction, operations personnel and commercial participants, to identify the top risks and management/mitigation strategies relating to each of the Project components (i.e. Project as a whole, Plant Onshore Facilities, Intake and Outlet, Transfer pipeline and Power Supply).

This process, where our experts were readily able to identify potential gains and losses based on their broad experience, immediately reduced the number of engineering options by 90%. This made more time available in a tight schedule to focus on issues with strong value-added outcomes rather than waste time on aspects that were never going to have a realistic chance of going ahead.  The result was far better design driven by quality and not by schedule.

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Channel Isle Power Station Process Improvements

​The Owner of Channel Isle Power Station, Territory Generation, had a need to implement a range of initiatives as the out-workings of a recent Chemical Systems audit. To implement these initiatives there was a critical requirement for the service of a full-time senior power station water specialist team to be based at the Power Station.

 

PWE provided the following services:

  • Power Station cycle chemistry

  • Evaporative cooling water system management

  • Water demineralisation expertise and advice for demineralised water production (including but not limited to on exchange, reverse osmosis, electro-deionisation, etc.)

  • Continuous monitoring (wet rack) systems

  • Reporting to Company Senior Management – development and implementation of reporting procedures

  • Training co-ordination and building staff capacity

  • Auditing of chemical monitoring systems and work practices including but not limited to laboratory practices

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Newman Water Treatment Plant for BHP

BHP approved construction of a new water treatment for the town of Newman in West Australia’s Pilbara Region to replace the existing facility that had been in operation for more than 40 years.

The new water treatment plant treats an average of 16,500 m3 of bore water per day and supplies drinking water to BHP and the town population of 5,500.

The treatment process includes pre-treatment to remove hydrocarbons and Cryptosporidium, reverse osmosis, disinfection and remineralisation.

 

PWE were appointed to provide the following detailed design services:

  • Civil Engineering design including

    • Bulk Earthworks

    • Surface water drainage

    • Equipment footing and slabs

  • Structural Engineering design including

    • Concrete foundation and ground slabs.

    • Process building steel structure

  • Building Design including

    • Architecture

    • Building services

  • Construction & Commissioning Support

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Jandakot GWTP - Clearwater Tank Roof Replacement for Water Corporation WA

Water Corporation required the replacement of the existing steel roof on the clear water storage tank with a more durable concrete roof.

The key requirement of the project was to remove the old roof and install the new concrete roof within a three week period during a planned shutdown period of one month.

To facilitate this, the roof structure was designed to be precast and supported on the existing walls and columns. The only concrete poured insitu was for the topping screed.

 

PWE were appointed to provide the following design services:

  • Structural Engineering Detail Design

  • Fabrication Drawings Review

  • Working the precast manufacturer to develop a concrete mix that would work with their concrete extraction process and which would avoid the use and ongoing maintenance associated with a surface coating on the concrete soffit originally specified. 

  • Detailed review of precast concrete panel shop drawings.

  • Precast concrete beam pre-pour inspections in the casting yard.

  • Construction Support
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