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Catchment permitting for Wessex spells flexible approach

An innovative catchment permitting approach for phosphorus, jointly developed by Wessex Water and the Environment Agency, is set to come into force in the Bristol Avon catchment in January. We take a closer look at the scheme

In quotes

Matt Wheeldon, Director of Assets and Compliance, Wessex Water: “Working with the EA on this has been a very positive experience; we are all trying to achieve the same thing. The Agency are looking to move towards good ecological status for watercourses as per the Water Framework Directive, but they are also cognisant that there is a finite pot of money. This shows that we can work with them to demonstrate ways in which we can get to those outcomes in a more financially sustainable and achievable way. "

Paul Hickey, Deputy Director of Water Quality, Environment Agency: “This really is a trailblazer initiative, and I think Wessex has shown a great deal of leadership in the way they’ve taken it forward. It was very much a partnership. We are encouraging other companies to think in the same way; I know other companies have expressed an interest, and it’s the sort of thing that could feature in their asset management approaches for the coming review. It’s still at quite an early stage for PR19, and I would expect more to come.”

by James Brockett

An innovative approach to the regulation of phosphorus developed by the Environment Agency and Wessex Water is about to be put into action in the Bristol Avon catchment.

The system of catchment permitting – which sees multiple sewage treatment works subject to collective phosphorus reduction targets - has been formulated over the last two years since the principle of the approach was included in Wessex Water’s business plan for AMP6. Improvement work under the new permits will get underway in January 2017 and be monitored closely over the subsequent three years.

Only a quarter of the Bristol Avon catchment – which covers the area east and south of Bristol and includes Royal Wootton Bassett, Chippenham, Bath and Frome – is currently classified as having good ecological status under the Water Framework Directive. Phosphorus in the watercourse is one of the key reasons for this, with discharges from sewage treatment works being a significant contributor. However, with Wessex Water having 66 sewage treatment works in the catchment and its larger sites already achieving good limits of 2mg/l P or lower, it became clear that capital investment at many further sites was difficult to justify on cost-benefit grounds.

“We have been in dialogue with the agency about this for several years – well before PR14 – ever since it became clear that the costs of upgrading individual sites to meet phosphorus standards under the Water Framework Directive were going to be prohibitive,” says Matt Wheeldon, Director of Assets and Compliance at Wessex Water. “We both recognised that given the number of sites involved and the cost of improving each of them, there was a risk that nothing was going to happen. The EA made it clear to us that they were open to innovative approaches.

“With this in mind, we went away and came up with an approach that would look at the total tonnage of phosphorus entering the watercourse. This, after all, is the overall outcome we are all concerned with, whatever the individual output of any capex or opex solution we pursue.”

Since 2000 Wessex Water has installed chemical dosing with ferric sulphate – a typical capex solution – to deal with phosphorus at the larger sewage treatment works in the catchment, but this is a relatively expensive option both in terms of upfront cost and ongoing running costs. Rather than investing heavily, and uneconomically, at a large number of further sites the company wanted to pursue a mixed approach using more opex solutions, such as optimising or improving the dosing processes it already has. While there are gains to be made from these solutions they have a less certain outcome than capex investment in new processes, hence the need for a less rigid, risk-sharing permitting regime.

The idea of setting Wessex a catchment-wide target for reducing phosphorus was one to which the Environment Agency was very much receptive, explains the EA’s Deputy Director of Water Quality Paul Hickey.

“We have been actively encouraging the concept of catchment permitting and flexible regulation for some time,” says Hickey. “Achieving environmental standards obviously involves a cost both in terms of building assets and the operating costs associated with them, and we were thinking about how we might flex our regulatory approaches to maintain the same safeguards to the environment in a more cost effective manner. So on the back of some of that previous thinking, between Wessex and ourselves we came up with this concept of looking at all of the assets in that catchment and thinking about how we might regulate that.

“If you say that you will take a certain load out of the environment on phosphorus across all those assets, but you can do it in a more flexible manner, it gives you a much better basis for looking at innovation and it will be more cost effective.”

Catchment permit design

Once the concept had been established and included in Wessex’s business plan, much detailed work has followed to establish which treatment sites made the most difference to P levels in the watercourse and should therefore be included in the permit. The eventual list of 24 includes the treatment sites where there is most scope for improvement and those which are most influential, because of their size and position in the catchment.

Each has been assigned a ‘stretch target’ - an ambitious target for phosphorus load reduction expressed in tonnes per year – which Wessex will aim to hit but will not suffer a penalty if they do not. More important in compliance terms is the ‘catchment load target’, which when the targets are added together for the all the sites, form the target reduction which must be hit for the whole catchment. Finally, each site retains a baseline individual permit under the EPR (Environmental Permitting Regulations) at a lower level to pick up any clear environmental breaches.

“A lot of the bits of kit that traditionally go in for phosphorus removal can achieve more if they are worked harder,” says Hickey. “But there’s always a chance that there will be a blip in performance and then it would be non-compliant. Because companies are rightly quite concerned about the risk of non-compliance, they tend to put extra interventions in place to prevent that. By regulating across the whole catchment we can allow a little more risk to be taken, because other sites can compensate for one another; but from my perspective it’s important to have that backstop, if you like, so that no site goes beyond a minimal level and the environment remains protected.”

Overall, 11 of the sites in the programme are set for capex solutions and 13 will be given opex solutions. Nine works have been assigned stretch targets that are below 1mg/l, compared to 13 where the target is 1-1.5 mg/l and two which have targets over 1.5 mg/l. The improvements are projected to remove 47 tonnes of phosphorus annually from the catchment while being delivered at a £20M lower cost than a traditional approach.

Further applications

“This approach is about doing things in a different way, in order to get more environmental benefits for lower cost – that’s got to be a good thing,” says Wheeldon. “Technology has been the traditional way of making step changes in environmental outcomes, but in this instance, it is changing the way we are regulated that enables that improvement. We need to look at all possible ways of improvement at lower cost and so for us, it’s a no-brainer.

“If we can get this approach to work for us, as part of a one-to-one relationship with the regulator, then it may well work to extend that thinking to a wider group of stakeholders, tying all the people who contribute towards watercourse quality in a catchment into the same environmental outcome. Once this trial has proven its worth, then that will be the next step forward.”

Hickey says that catchment permitting is an approach that could be applied to other parameters than phosphorus, although it is likely to be the most relevant parameter in the short term as it is the substance in the Water Framework Directive that is falling most heavily on water companies. Innovative work is also underway in water companies on tertiary treatments to complement chemical dosing; achieving good ecological status under the WFD will also require getting to grips with pollution from diffuse sources, from agriculture and elsewhere. However, catchment permitting is an approach that can complement this other work and can achieve real progress on phosphorus at a more affordable cost.

“One of the things that’s really important for us in this is we want to create an environment for innovation,” concludes Hickey. “We want to get people to think laterally about how to achieve environmental standards in different ways, and we would flex regulation to encourage that.

“We’ve been actively promoting this and I’ve personally written to all the water companies setting out the principles that we want, how they might look at catchment permitting and encouraging them that this is the sort of thing that we want them to be doing. We are in this window at the moment where companies are thinking about their next business plans, for the coming review, so we will really go about saying there’s a lot of wins for everybody in this. Obviously we’ve got to have the right checks and balances, but a number of companies are looking at it very seriously. We’ve proven the concept, and so it’s really for companies to look at their own assets and think where this might bring most value.”

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