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Dear Sir,

[Re: Rowan Hallett's water articles of February 27 and March 6]

While I applaud Ms Hallett's commitment to the environment I must take issue with some of her comments. Although not an oceans specialist I am a water engineer with almost 40 years of experience, 25 of them in Bermuda.

Government decided to build the Tynes Bay SWRO facility to support the public water supply system, based upon the then available information. However, thus far, I have been unable to determine the engineering, financial or environmental benefits for Bermuda in doing so at this time, especially since water sales are probably very similar today to what they were a decade ago. The 600,000 gallons per day SWRO plant has been commissioned and the facility is currently being expanded to 1,200,000 gallons per day.

Seawater reverse osmosis water treatment plants usually operate at around 40 per cent recovery with 40 gallons out of every 100 gallons pumped out of the ground converted to potable water. The 60 gallons of waste water (brine) is normally discharged down a sealed borehole, deep below sea level.

At present, when needed to supplement the water production from the existing lower cost fresh and brackish water treatment plants, the Tynes Bay plant abstracts around 1.6 million gallons of seawater per day from a well over a hundred feet below sea level. The one million gallons per day of brine is mixed with the 16 million gallons per day of cooling water from the adjacent incinerator plant and returned to the sea. The salinity of the combined discharge is increased by approximately 3.5% over normal seawater. Government advised that the completed Environmental Impact Assessment concluded that these discharges would have a negligible environmental effect.

Even if the water was abstracted directly from the sea and the brine returned directly to the sea, over time the salt balance would be stabilised due to fresh water inflow and mixing. Bermuda does not retain all of the water it obtains from fresh, brackish or seawater sources. Once used, this water is discharged into a sewer system for ultimate discharge to the sea or via cess pit seepage back down to the water table where there is a constant flow of excess water to the sea. Excluding the contribution of percolating rainwater, the quantity of seawater abstracted for treatment in Bermuda is miniscule when compared with the fresh water run-off from the land into the ocean.

I do not believe that seawater desalination is in itself an environmental issue and there are areas in Bermuda where there are environmental benefits to using seawater desalination, particularly when there are no low cost renewable fresh or brackish ground water resources available and where the only alternative is to truck it in. There are of course other environmental issues relating to SWRO, including the need for a great deal of electrical power, which increases Bermuda's oil imports.

There is a wealth of information available on Bermuda's water history, industry and future technologies for making desalination more environmentally friendly. Should Ms. Hallett wish to learn more she is most welcome to contact me through your paper.

Finally, I was employed by Government during the last long term drought experienced in Bermuda, which was between 1989-1991. To promote conservation I sketched out and with my then Principal Engineer, Trevor Gilchrist, we developed the 'Drippy' stickers [see above], which were printed at Triangle Press and widely distributed along with 'Reduce Re-Use Repair' flyers printed by the Ministry of Community Affairs. The campaign was a success; water mains were kept full and a great deal was learned as a result of the drought. Although I am not convinced about the beneficial impact of the current conservation programme, Mr. Drippy's heritage is 100 per cent Bermudian.

Ian Saunders[[In-content Ad]]

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