Thames still banking on Abingdon reservoir

Peter Minting interviews Dr Peter Spillett, Thames Water’s environment and quality manager.

Thames would like to build a reservoir at Abingdon, despite abandoning a similar plan at the consultation stage in 1993.

Would the water be piped all over Thames’ territory or is it intended to supply mainly London and the upper/middle Thames?
Most of the water would go in a downstream direction, i.e east towards London as this is where the population is greatest. But some of it would go as far west as Swindon.

So local residents would benefit from the scheme?
In my view, yes; as well as an improved water supply the scheme would provide many employment opportunities in the area, during the construction phase and afterwards. We would take steps to ensure that traffic disruption in the area would be minimised.
There would also be many leisure opportunities ­ we have already received several interesting proposals for activities at the site although some of them, such as white-water rafting down the embankment, seem somewhat less likely! Overall we think the leisure potential is enormous, and we could create an amenity as popular as that at Carsington or Rutland Water.
The potential for wildlife and fisheries would also be maximised ­ for instance we could create shallow lagoons for wading birds and waterfowl.

Is the design likely to necessitate many compulsory purchase orders or the flooding of any SSSIs or listed buildings?
No, that is one of the main attractions of the site. Most of the land is farmland, and therefore only a few landowners would need to be served with a compulsory purchase order (CPO). The other landowner of significance is the Ministry of Defence (MOD), which owns a large depot at Steventon.

Is there a minimum size for the Abingdon reservoir and if necessary, could it be built somewhere else?
The volume of the reservoir proposed in Thames’ first application in 1993 was between 75,000Ml and 150,000Ml. Below 75,000Ml, the reservoir would probably not be an economic option, and there are no other sensible locations for a reservoir of this size in the area.
This is partly due to the underlying geology because the suggested site overlies a layer of impermeable Kimmeridge clay, which is ideal for reservoir building. The first plan featured a reservoir 3.75km long by 2.5km wide. Any future proposal is likely to be for the same location, west of the A34 road south of Abingdon. The reservoir could not be any larger because the site is limited by the A34 to the east, the village of East Hanney and A338 road to the west and the London to Bristol railway line to the south.
The area under consideration covers approximately 14km2. However, not all of this would be used for the reservoir, as much would be used for operational infrastructure, landscaping and access roads.

By abstracting water during high flow and putting water back in at low flow, the flow pattern of the river would presumably change. How would this be managed to prevent changes to the river’s ecology?
You have to remember that the Thames is already a highly regulated river, with a complicated system of locks and barriers. By taking water out of the river at Abingdon during high flows in winter and putting water back in during the summer, it would be possible to prevent the loss of valuable water to the sea.
The main purpose of the reservoir would be as a regulating reservoir, to help maintain flows and retain adequate supplies. Up to 500Ml/d from the Abingdon reservoir could be used to top up other reservoirs when necessary, such as the Queen Mary reservoir near Staines in west London.
If we had more water available we would actually be able to help migratory fish such as salmon, by releasing water to increase flow. Migratory fish such as salmon and sea trout need rapid flows in the estuary, to stimulate movement upstream from the sea to breed. Of course this would be quite a challenge to manage, as during a drought the public would probably not be too pleased to see us releasing water.

If the Abingdon plan is not approved, what will Thames Water do instead?
There are other options for increasing supplies. However, ongoing studies under our best practical environmental programme to compare a number of factors, including practicality, cost and environmental impact, show a reservoir would continue to be the best option.

Would you be forced to buy bulk supplies from other water companies?
We currently only buy a very small amount (0.1Ml/d). We are not opposed to bulk purchasing but it does depend on the water being cheaper than that which we already have available. We already sell some of our own water to small supply companies, like Essex and Suffolk Water and Three Valleys Water.

How would the reservoir be funded?
Under Ofwat regulations, if customers are to receive more water then they will be expected to pay for it. But there are other ways to fund such a project ­ for instance we could set up a private consortium with its own shareholders to build the reservoir. Other water companies might want to invest; in fact several other water companies have expressed an interest.

Will Ofwat’s price review for 2000-2005 (AMP3) affect Thames’ preliminary plans for the reservoir?
In a way, no, because the scheme would not be up and running for 10-15 years, even if an application was approved, The reservoir would take around 8 years to complete.

What other options for increasing supplies is Thames likely to consider?
We are looking at a number of options for increasing supplies. In our view, the Abingdon plan continues to be the ‘best practical environmental option’ (BPEO). This conclusion has been based on extensive research of all the available options. Alternatives include aquifer storage and recovery (ASR). Aquifers can be used as reservoirs, if they can be filled to capacity using treated water.
But ASR is technically quite complicated and there are a limited number of suitable aquifers in the Thames region. This is not to say that we will dismiss ASR altogether, as it is obviously important not to put all of your eggs in one basket.

Thames is now sinking boreholes across London to tap groundwater, which has been accumulating due to a decline in industrial demand. Will it be treated for water supply, or used to increase river flows?
The water will eventually be used for public supply, although it will prove to be an expensive resource to treat as it is of poor quality. It will require treatment even if disposed to rivers as in its raw, saline state it could be toxic to fish. We have no liability for the potential problems caused by the rising groundwater [e.g tube line flooding or foundation damage]. Nevertheless, we hope to extract 50-70Ml/d from the boreholes.

In general, how do you plan to increase supplies? Do you work to a maximum estimate of population and demand?
We don’t work to a maximum as a general rule, instead we work with a ‘central best estimate’ of predicted demand. We use demographic data in line with government estimates and our demand forecasting methods are consistent with industry best practice from UK Water Industry Research (UKWIR).

How would you rate the following in terms of potential for water conservation?
Free metering: By themselves, free meters will not be that effective unless there is a pricing mechanism such as seasonal or rising block tariffs. There is no real incentive at the moment, especially considering that Thames¹ customers have one of the lowest bills. Thames has 16% of connected properties metered ­ a fairly low rate of penetration, given the relatively high socio-economic profile of the region.
‘Hippo’ bags in toilet cisterns: The effect is probably quite small, compared with other initiatives, however, we think it is important to educate people about the need to save water.
Low water-use toilets: Non-siphonic toilets can be installed after January 2001, in line with the water supply (fittings) regulations 1999. We think it is likely that dual flush toilets will provide greater savings than single low flush WCs. We are currently assessing the effectiveness of these devices.
Greywater recycling systems: Effective systems do have the potential to save around 30% of water, but the technology is still in its infancy. We are currently involved in a number of projects assessing the effectiveness, reliability and public perception of water recycling technology for individual houses and on a large scale. The water industry needs to be confident that the systems are well-designed and installed. It also depends on developers having the courage to adopt them as a standard feature of new houses.
Customer pipe leak repairs: If more people were metered, it certainly true that many more customer pipe leaks would be discovered.

How realistic are Ofwat’s new leakage targets for 2005?
Not very realistic at all. We provided Ofwat with a very detailed economic analysis of the potential to reduce leakage in our area, but our research has effectively been dismissed.
Next year’s target is to reduce leakage by another 12.5%, despite the fact that Thames has dramatically reduced leakage since 1995 and spent around £300M on leakage reduction.
It is likely that there will soon come a point where it will no longer be cost-effective to spend more money on leakage reduction. And bearing in mind the expected reductions in capital maintenance [following the latest price review] it will become increasingly difficult to maintain the improvements we have made.

  • Environment Agency remains unconvinced
    “The Environment Agency (EA) is not totally averse to new reservoirs, as long as all the available options have been properly explored. But I have to say that at the moment, Thames’ leakage record is not that good; Thames still loses 28% of the water it puts into supply as a result of leakage. This is a significant improvement on 40% in 1995, but there is still a long way to go ­ there are now other water companies in the UK with leakage rates of just 10-12%. Further leakage reduction would be just as good an idea as a new reservoir. A reservoir such as the one suggested at Abingdon would only increase supplies by 5-10%. We feel Thames is trying to avoid the treadmill of reducing leakage, simply because it is hard work. “To be honest, I’m fed up with people in senior management [of water companies] sounding off about the need for new reservoirs. Anglian Water started doing the same during the last drought in 1995, but they now seem to have given up on the idea. Thames has not actually proposed a new reservoir in its next 25 year plan, but it has proposed to look into the various options for increasing supplies, which include new reservoirs. We welcome forward thinking, but at the moment I think Thames would run the risk of being seriously embarrassed if such an application became subject to a public enquiry.” EA director of water management, Geoff Mance.


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