St Mary’s To Get New Desalination Plant

Desalination plant to be replaced

Councillors have agreed the purchase of a new desalination plant.

They haven’t gone for the cheapest quote – the cost options from tendering companies ranged between just under £875,000 to £347,000, and a  £478,000 scheme was thought best for St Mary’s.

Neville Gardner, Chief Technical Officer from the Council, pointed out that they didn’t have to go for the lowest bid. That cheaper option would take up too great a space for the compound.

Councillor Fred Ticheurst said they had got the best value for money and members had backed the advice of the Council’s consultants’ report.

The cost of the replacement plant will be fully funded from within the £1.5m of DEFRA grant funding already provided in this financial year.

Councillor Chris Hopkins wanted to know whether the current equipment could be resold and or should it be kept for a, “for a rainy day.” But Neville felt it had “run it’s course.”

The technology used in the 1993 reverse osmosis desalination plant has been improved in recent years.

He said that the current plant is well maintained but is showing its age. The new system will increase capacity by 26% and that will be useful if there’s population growth but also if water quality regulations change.

Currently the desalinated water is mixed with aquifer water to create an acceptable drinking supply. Neville told members that Scilly had high levels of nitrates in the water because of chemicals used in flower farming and that was likely to be a consideration for another 100 years.

If the acceptable levels of water chemicals change, more desalinated water may be required to mix with water from other sources and this new plant could cope with that.

Neville added that the current water supply is safe.

The new plant will be more efficient. In summer, the existing unit consumes 75kW of electricity each hour, around the clock. In the future this could drop to 55 or 60 kW per hour.


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