Site surveys in the Highlands
Monitoring and maintaining assets dispersed over a large and remote area is a particular problem in northern Scotland. Hyder Consulting's Gareth Jones discusses the responseWhen a water authority is responsible for an area of 40,000km², reliable remote monitoring of water and wastewater treatment plants and equipment is a necessity.
"Our area, for all its ruggedness and beauty, presents some fairly unique problems from a water service point of view," explained John Hutton of NoSWA. "You don't need to be a mathematician to work out the potential scale of the cost of monitoring and maintaining assets that are so geographically spread. That is why we have initiated a major initiative called Project Kestrel to optimise our use of telemetry systems."
Previous investment in telemetry and communications resulted in the development of six systems for different purposes. Investment in both site-based equipment and core telemetry servers has been considerable. NoSWA had equipment installed at approximately 1,300 of its 2,500 operational sites.
Project Kestrel was about setting consistent standards for data capture and processing. The aim is to increase SW's business benefit, while continuing to get value from its inherited infrastructure.
Hutton explained how the overall objective was to make sure NoSWA had the input/output (I/O) capability to meet future requirements and ensure it would fit into the wider strategy associated with its integration into SW.
As part of this objective, Hyder Consulting was appointed by NoSWA to review a number of sites in the Highlands and Islands region for the provision of telemetry hardware, involving site surveys, procurement management and implementation project management. All sites have been audited to ascertain I/O requirements in line with NoSWA's new standards and to assess power and communications options.
Each site has been assessed using a common methodology which takes into account the following elements:
- existing telemetry equipment,
- space constraints,
- level of existing automation,
- electrical systems,
- motor control centres (MCCs),
- communications media - fixed public switched telephone network (PSTN), global system for mobile phones (GSM) or scanning telemetry,
- power failure back-up.
Throughout the audit, information was stored on an intelligent database, which was then used to produce the final tender documentation.
Typical of the sites to be upgraded was Melvaig WTW, on a remote peninsula of Wester Ross, and Aviemore Service Reservoir.
The Melvaig works comprise a service reservoir, battery-powered sodium hypochlorite dosing pump systems for the Melvaig and north Erradale areas, wind generator, solar cell and battery-charging equipment. The dosing equipment and battery-charging control panel are located inside a brick building above the service reservoir.
Following Hyder's survey of the site, a new telemetry station will be housed in the existing brick building. Both water distribution systems will be provided with chlorine analysers and the water sample for each system will be sourced from their respective delivery pipework. The analysers will be powered from the existing battery power supply and two 4-20mA chlorine levels will be routed to the telemetry outstation. A level transmitter will be installed within the reservoir inspection chamber with the level signal also being routed to the outstation.
An existing mechanical flowmeter on the delivery pipework provides flow proportioning pulses for the sodium hypochlorite dosing pumps. New pulse heads are to be added to provide volt-free pulses for telemetry monitoring. These pulses will be interfaced to a frequency/current converter and routed to the outstation in 4-20mA form. Because of the increased power demand, an additional battery will also be fitted. A PSTN communications system links the monitoring equipment.
In many cases a fixed communications link is not an option due to the prohibitive cost of installation and the lack of coverage from existing scanning radio telemetry. Consequently, the survey team carried out a coverage evaluation of GSM service providers in the area.
The Aviemore Service Reservoir will utilise GSM technology. The telemetry outstation will be installed in a glass reinforced plastic (GRP) kiosk adjacent to the reservoir wall. The transmitters and meters will be similar to those at Melvaig, but the site will utilise a new solar cell for its power supply.
Because many of the surveyed sites lack suitable power supplies, they will rely on solar power and windmills to generate energy for the outstation, communications and instrumentation.
In many cases, the first challenge was finding the sites to be surveyed. For this reason, the survey team utilised a global positioning satellite navigation system connected to a moving map. During site visits these were used to show real-time location information and greatly assisted with finding sites.
Throughout the site surveys a number of issues had to be kept strongly in focus. Principal among these were:
- the need to retain current operation of systems,
- staff availability to support additional equipment,
- staff training in the function and maintenance of additional equipment,
- the degree of distributed control,
- identification and use of critical instrumentation,
- identification and handling of critical alarms,
- requirements for any emergency shut down systems,
- remote operation of outstations,
- earthing and lightning protection.
With such a wide range of considerations, a survey team was chosen with extensive experience of water engineering, telemetry, instrumentation and wiring, and process control systems. The survey programme has been closely coordinated with relevant works supervisors as the active involvement and cooperation of operational staff is key to ensuring the safety and success of the project.
From the sites surveyed, 50 have been selected for upgrading based on operational priorities. Detailed costings for the upgrade of each outstation have been determined, which include assessments of the ongoing costs in areas such as communications line-rental and licensing, maintenance and software support.
The contractor appointed to the Highlands sites is Aird Walker & Ralston.
Upgrading work is scheduled for completion by August 2002.