Long Sea Outfalls project

In line with many manifesto pledges, PSD wanted to put in a Sewage Treatment System. We asked one of the leading companies in the UK to come here and tell us what we needed to put in. Intertek Metok came over and measured our tidal flows, they took samples of our water, they sampled the sea bed around the outfall, took samples from the beaches, they measured the health and vitality of shell fish and plant life around the outfall and beyond.

Their scientific findings were startling and unexpected. They found the tidal flows in the Russel were fairly unusual and somewhat unique in that they quickly took the waste water up around the north of the island, churning it as it went, subjecting it to sunlight and by the time 24 hours was over the waste waters had been treated.

The fast flowing waters acted as a natural treatment system.

The samples of the sea bed and plant life showed that the effect of the releasing waste water into these fast flowing waters was having a negligible effect on the environment.

This was surprising and counter-intuitive but the science was challenged and found to be robust.

There is no evidence our bathing waters are effected, water quality at the beaches is very high.

They recommended Guernsey install a diffuser section to the outfall pipe to aid with initial dilution and meet the UK standards, a diffuser which is part of the Long Sea Outfall project.

The cost estimates for the civil and mechanical elements of sewage treatment, plus the land needed ran to £50m and with running costs of circa £2m every year, the lifetime costs of sewage treatment over the 25 yr life of the plant would amount to £100m for the people of Guernsey.

The lack of evidence for a need for change due to the low environmental impact of the unique waters into which the waste water was released, coupled with the costs involved, gave PSD no choice but to recommend to the States we do not proceed with full sewage treatment.

There were some improvements we could make and we have put screening to remove any solids such as plastics, cotton etc. and will diffuse the release of waste water at the end of the pipe to assist initial dilution and subsequent dispersion which will minimise any visual impact at the surface.

There simply is no scientific evidence to require sewage treatment no matter how uncomfortable that feels.

The professional cost estimates of the infrastructure required plus running costs running into tens of millions are sums of money best left unspent.

In answer to some of the allegations Deputy de Lisle raises:

PSD believes that an appropriate solution for the long term, sustainable, environmentally sympathetic method of dealing with sewage has to be achieved for many generations to come and this is what is now being proposed with the replacement of the long and storm sea outfalls.

David de Lisle is correct that the initial proposal to deal with the outfall was to repair the existing pipe at a cost of around £4m, however this was for a project that is far different from what is being proposed now.

Unfortunately the original proposal to replace the long sea outfall has proved to be impossible as it is laid within a flooded tunnel that would be impossible to drain down and access without excessive costs being incurred, i.e. probably close to the figures of the new outfall. Also, it was only to replace the long sea outfall – the current proposal now includes for the short, or storm outfall, which is potentially a greater current source of pollution than the long sea outfall. The project also includes a diffuser until to aid dispersion of the waste water and reduce surface visual effects. This greater cluster of projects is unfortunately going to cost more.

The costs Deputy de Lisle quoted as £6.1m, £10.9m and £3.4m for primary, secondary and sludge treatment respectively make no account for the other contract costs required, such as site set up, preliminary items, insurances etc which are all part of normal project and contract administration. The same paper quotes these costs (with a risk allowance) at £7.4m plus works at £2.5 million for site security, landscaping, odour control, instrumentation & control – all items necessary for a treatment works to operate. Nor does he recognise the well understood uplift in costs that come from the “Guernsey Factor” which is currently running at around 1.8 x average UK costs. These two “omissions” alone raise the £20.4 million he quotes to almost £55 million in line with our predicted costs.

The simple fact for our island is that:

a) we have two critical outfalls that are in need of urgent attention before they fail catastrophically and cause untold long term pollution of the Bay and other surrounding water, and

b) they will be needed regardless of whether sewage treatment is provided in the future or not (albeit maybe of a slightly shorter length, but we cannot wait to address the issue of the deteriorating condition of the pipes).

The cost of these pipes at almost £20 million is substantial, but the PSD Board are convinced that this is essential investment and is not being implemented as a “second best” option; it will provide a long term, cost-effective solution to a very difficult problem without any of the issues that would come with a land based treatment facility.

For anyone wishing to review the findings of the scientific survey, page 290 of the January 2012 billet is a good summary.

http://www.gov.gg/CHttpHandler.ashx?id=5382&p=0

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Responses

  1. You seem most insistent that full treatment would cost Guernsey £50M, despite our quotation for a fully fabricated system to drinking water standard at £13M. Please enlighten us as to where the remaining £37M would be necessarily spent.

  2. I said in debate “This proposal as presented represents a solution for dry weather flows only, such a size would not be permissible by the Environment Agency in the UK.

    A treatment works must be sized to treat at least 3x dry weather flow. This plant, as Deputy de Lisle informs us, is capable of a throughput of 16,000,000 litres per day, it therefore needs to be three times the size to cope with Guernsey’s requirements, it also has no Guernsey uplift factor to it”


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