Royal HaskoningDHV has been appointed as Electrical and C&I Consultants for the investigation, master planning and phase 1 implementation of the Mhlathuze Water Scada Upgrade Project.
Based in Richards Bay, Mhlathuze Water’s area of supply covers some 37 000 square kilometres stretching from the uThukela River in the south and up the east coast to the Mozambique and Swaziland borders, around Vryheid and back to the uThukela River. Within this region, Mhlathuze Water has built and operates an inter-basin transfer, major water treatment plants, an offshore waste water disposal pipeline as well as operating treatment and sewerage plants on an agency basis for local municipalities.
The scope of the project includes:
* Upfront investigations and scada master planning.
* Specification of field instrumentation, infrastructure and automation systems at Nsezi Water Treatment Plant (WTP).
* Specification of field instrumentation, infrastructure and automation systems at Alkanstrand pump station.
* Specification of field instrumentation, infrastructure and control systems at the Weir.
* Design and specification of centralised control rooms for the Nsezi WTP and Alkanstrand pump station.
* Design and specification of a radio telemetry system that links Nsezi WTP, the Weir and Alkanstrand pump station.
* Design and specification of the A-Line effluent MCC at the Alkanstrand pump station to enable full automation of this system from the central scada.
* Preparation of the final tender document.
* Construction monitoring and supervision.
Approach
Information for the design work was gathered from site visits as well as from the Mhlathuze Water library and archives. The information retrieved provided detailed layouts of the plant as well as the monitoring points that are in use. Royal HaskoningDHV used this information as well as its experience and knowledge of control and instrumentation in water treatment systems to determine the requirements for critical process monitoring points for instrumentation that would add value to the operation of the works.
A radio propagation path study was performed to inform the design of the telemetry communication system between Nsezi, Alkanstrand and the Weir. Various control system architectures were evaluated during the master planning phase and these included plant wide telemetry communication to each plant area, individual PLCs for each plant area and remote I/O systems for each plant area.
Automation solution
Nsezi water treatment plant
A common services fibre optic infrastructure solution was selected for the Nsezi WTP as it caters for enhanced network flexibility and capacity for any future expansion services. The automation system solution consists of a network of PLC remote I/O systems for each section of the plant. These will be networked via the common services fibre optic infrastructure to the main PLC system. The PLC system will then be networked to a central scada server at the main water treatment works for process visualisation, logging, trending and reporting. A new telemetry system will be installed for the monitoring of the Mondi reservoir and the clarified water pump station.
Alkanstrand pump station
The individual PLCs for the A-line, B-line and C-line effluent systems will be connected to a new scada system that will provide for the visualisation and alarming of these systems at the new control room. A new telemetry system will be installed for transmission of mission critical data to the Nsezi WTP.
Raw water abstraction
Instrumentation upgrades as well as new installations will be performed at the raw water abstraction weir to enable suitable monitoring of this station. A new telemetry system will be installed for transmission of mission critical data to the Nsezi WTP.
Project benefits
* Improved monitoring of the water treatment and effluent process and systems.
* Enhanced operator visibility into the process.
* Improved fault finding capabilities.
* A high availability control network.
* Network architecture flexibility. A flexible fibre optic network was deployed underground that included the addition of fibre optic reel technology to cater for mobile equipment.
* The use of a common services fibre optic network reduces infrastructure costs.
* Improved sharing of production data with other plant stakeholders.
* Improved production reporting through the introduction of scada.
For more information contact Selvan Murugan, Royal HaskoningDHV, +27 (0)21 936 7600, selvan.murugan@rhdhv.com, www.rhdhv.co.za
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