Water supply in all weathers
With a lack of groundwater and limited storage capacity Jersey is designated an area of water scarcity. Howard Snowden tells WWT about challenges facing the water company
JNWC is similar to any small UK water company in terms of its management structure, but is part private-owned and part owned by The States of Jersey, who purchased a controlling share in 1981. “The company seemed to be undervalued and could technically be asset stripped,” says Howard Snowden, managing director and engineer of JNWC, “So The States took a share in the company to secure it for the benefit of the island.”
Since the water law’s inception, JNWC has been charged with providing Jersey residents ‘wholesome’ water. The word wholesome is a generic term which has been left undefined. This is seen as a problem by the PSD, which is currently drafting new legislation as a result. “At the moment anyone could make a complaint about the water and its very difficult as the regulator to say it complies with the definition of wholesome,” points out Gerry Jackson of the PSD.
“For water treatment and water quality we use the UK drinking water quality regulations as best practice,” says Snowden. “Our regulator wants to define wholesomeness and wants to use the UK definition. We don’t have a problem with that, but we don’t see the need for legislation when we already adopt it,” he adds.
The company operates two WTWs, the largest is located at Handois, central to the island and the second at Augrés in the east. Treatment is a two-stage process, comprising chemically-assisted sedimentation and rapid gravity filtration followed by sterilisation using a chloramine.
Until recently one of the works was manually operated, but both are now automated. JNWC also has plans to invest in a SCADA system. “We do have some SCADA and telemetry systems for remote control, but it will be enhanced,” claims Snowden. “This will go hand-in-hand with plant replacement and on-line monitoring to give us total remote control and a tool for planning how we treat and use water in the future,” he adds. Most laboratory testing is carried out in-house apart from extensive chemical, bacteriological and pesticide checks which are under- taken by Southern Water Scientific Services.
At present, not all of the island is covered by mains water. JNWC estimates 10% of the population are using private supplies, including boreholes, rainwater tanks or water bought from hauliers, who purchase direct from JNWC.
“We are expanding our distribution system by 6-8km of mains a year,” says Snowden. “We finance our mains link programme to try and cover as many highly populated areas as possible. For the scarely populated areas we have a scheme where we subsidise the cost of laying a main, but ask residents to contribute.”
JNWC’s aim is to offer mains supplied water to all properties on the island, but expansion runs simultaneously with refurbishment and the company does not yet have a date by which everyone will be on mains water. “We are an old organisation with ageing infrastructure. Mains are at the end of their operational life,” explains Snowden. “JNWC is renewing mains all the time and we plan to increase the rate of renewals in the future.” Typical winter demand is appoximately 18,000m³/d and can rise in the summer to 30,000m³/d. The major increase in water demand tends to be for gardening and is no longer tourism lead. Jersey residents require a hose pipe licence and other watering devices, such as sprinklers, are metered.
Water resources are limited. The geology of the island is predominantly impermeable rock with no aquifer, apart from St. Ouen’s bay on the west coast, where a small amount of water can be abstracted from a sand aquifer. Approximately 97% of the total resources are surface waters. JNWC has constructed a number of impounding reservoirs, the most recent of which was completed in 1989. “Queen’s Valley reservoir has increased our storage capacity by 80%,” explains Snowden. “Because of the environmental issues with building a reservoir it took 17 years to get through planning and during that time the island suffered severe water restrictions.”
When its six reservoirs are full Jersey still only has 120-days supply of water, at typical daily demand. Rainfall is not particularly high and follows patterns of neighbouring France. “60-70% below average in a year can be quite damaging to our water resource situation,” claims Snowden. “Whether its global warming, or a cyclic event, rainfall trends seem to be intense dry periods and intense heavy periods. A good example has been September  where we had nearly the month’s rainfall in four hours and the rest of the month, nothing.”
JNWC takes a positive attitude towards leakage control and reducing water wastage. Flowmeters are installed at strategic locations to detect abnormal water flows. A waste detection team surveys the distribution system to detect leakages using noise correlation equipment.
When natural water resources are depleting, a desalination plant provides a standby supply. The first desalination plant was commissioned in 1970 and was a bold decision for the company.
The original plant used a multi-stage flash distillation process, which burned approximately 50,000 l/d heavy-grade oil. Total operation costs amounted to £4,500/d. “In 1988 the old plant was at the end of its life. The decision had to be made on whether to refurbish, or build a new replacement plant,” Snowden remembers.
JNWC contracted Weir Westgarth to provide a new desalination plant using reverse osmosis. It was officially opened in July 1999. The existing plant produces a maximum 6,000m³/d and was based on the output of the original plant. Demand has doubled in those 30 years, mainly because of the extension of the distribution system and the plant will be extended in the near future.
Desalination currently requires 1,750kW of power at full load. Filtered seawater is applied to the membranes at a nominal pressure of 65bar. All suspended solids greater than 0.001µm are removed and 45% of the sea water is converted into fresh water. The pure water is discharged into a small holding tank, from where it is pumped into a reservoir for blending with natural waters. It is eventually forwarded for treatment and distribution. Brine is returned to the sea.
Island plan,BR> Further expansion of JNWC will derive from increased demand for water, or changes in water treatment requirements and quality standards. Provisions for planning and development involving land use are covered in the Jersey Island Plan 2002. The document sets criteria for future development of the island. As well as specific policies on planning applications, it presupposes how utilities will develop over the next decade or so. Section 13: Natural Resources and Utilities refers to JNWC.
The island plan states the company may require expansion of existing facilities to accommodate increased water capacity, waterworks sludge treatment and advanced water treatment technology. It may also need abstraction ponds and pumping stations. “We are pleased the island plan has taken account of the need for utilities, particularly water, to be able to develop and use land,” says Snowden.
JNWC work is typically carried out in-house or contracted out to the UK. “We can’t employ UK contractors unless they obtain a licence to work on the island,” explains Snowden, “But its normally just a formality. We are a specialised industry and need specialised contractors”