Examination of Witnesses (Questions 380
WEDNESDAY 21 NOVEMBER 2007
Is there any sign that anybody is actually taking that work forward?
Mr Wray: Yes, there is. All water
companies and waste companies are in the process of putting together
for the first time through public consultation, 25 year strategic
statements. I know from my own companyand I believe for
Thames as wellthese are issues that we area taking very
seriously and we are making practical suggestions about how we
can start that journey, how we can practically re-engineer the
networks over the long period of time to start to contend with
some of these issues.
What assumptions on the weather are you making? Are you following
the recommendations of the Foresight Report, for example?
Mr Wray: Not only the Foresight
Report, but the Climate Change Reports and any relevant
and current information that we can find. We are taking that data
and trying to predict what it is we will be dealing with in the
future, what does it mean in practical terms for the drier and
wetter climate that we are going to be dealing with? What are
the implications on how we deal with the future sewerage and water
supply demands of the future?
Mr Drew: Moving onto sewerage,
just a question for you, Tony, in terms of where you are with
reed beds, for example. I believe Gerald Noone is known to you
for some time.
Chairman: He is not well known
to me. Who is Gerald Noone?
Q382 Mr Drew:
Tony will say in a minute who Gerald Noone is, but there was quite
an instructive dialogue going on about other ways in which we
can deal with this enormous problem of sewer drainage. Can you
say what your current attitude is to reed beds now that Gerald
Noone has gone? You might also like to say who Gerald Noone was.
Mr Wray: Gerald Noone was a previous
officer of the company who led some of the company's research
thinking about methods of treatment. Reed beds figure in our armoury
of tools and techniques for dealing with sewage. We are looking
at their application across a whole wide range but we have to
contend with huge amounts of sewerage from large urban conurbations
like Birmingham and Coventry through to very small amounts of
sewerage in rural locations. The flow rates that you have to contend
with there will dictate to some extent the nature of the design.
The other thing that we have to deal withand it is a feature
I think of the water industry from what I can see, certainly for
the past 20 yearsis a huge amount of investment driven
towards improving quality, quality of drinking water and quality
of final effluent before it is discharged to the water courses.
Because of that we now enjoy in the UK some of the highest standards
anywhere in the world, but I think there is now a question to
be asked about shifting the balance of that investment on from
quality to dealing with quantity and the volumes that we have
to deal with into the future.
Q383 Mr Drew:
Can I just ask Thames Water if they have a similar interest in
Mr Aylard: Certainly we have,
but we have the same issue as with SUDS about the space required.
If you look at our Becton plant which treats the sewerage from
three and a half million people you would have to fill a full-sized
tanker every two seconds to cope with that amount of effluent.
There would have to be a reed bed larger than anybody could possibly
comprehend. Even with some of the smaller works it is very difficult
to find the space. Also ideally with a reed bed you need a natural
drainage through it so you have to have the right degree of landscape
to make them work properly. We do have some.
Mr Collington: We have several
sites that have reed beds and they are an effective method of
treatment, but it tends to be for the smaller sites.
Q384 Mr Drew:
Could I ask about the issue of what expenditure you are prescribed
to spend in the area of sewerage disposal by Ofwat? Do they give
you enough flexibility or would you ask for more? I know you have
to raise the money, but Ofwat have been quite difficult in terms
of the amount of money they have expected you to spend on that.
Mr Aylard: We have to make a good
case to Ofwat for any expenditure of customers' money. That is
quite right, they are the economic regulator and are there to
protect the customer. We have to be able to show that any work
we want to do either has a legal driver to it or it is to do with
essential maintenance of existing assets, or that it is an improvement
to customer service which customers would support. One of the
things we are doing in the strategic direction statement Tony
mentioned just now is that we are proposing that we would design
waste water assets to cope with a one in 30 year rainfall scenario
rather than a one in 20. Ofwat will want us to show that customers
understand that and are willing to pay the extra costs of doing
things to a higher standard. It is the point that the local authorities
made earlier about balancing risk and cost in a sensible way.
Q385 Mr Drew:
How does that compare to the previous session? Oxfordshireand
indeed Duncan from Gloucestershirewere saying they were
having to prepare possibly for a one in 300 event. You are talking
about one in 20 or one in 30, that is a pretty differentiated
Mr Aylard: Even that is very expensive.
In Ofwat's defence in the previous five year price round the allocated
us £80 million to relieve sewer flooding in individual properties
in our area; this five years they have given us £320 million.
That will relieve sewer flooding in about 6000 properties.
Q386 Mr Drew:
In terms of the changes the Government is now proposing for you
to have as your re-adoption of responsibility, if you like, for
the sewerage, how do you welcome that? You said you were willing
to do it, but this is big money and you are going to end up with
all those problems that I get when my sewer blocks and that is
because nobody at the moment wants to take responsibility.
Mr Aylard: I am not saying that
we welcome it but it is something we are geared up to do; it is
Mr Collington: It is going to
be quite difficult; we should not underestimate that. For Thames
we currently have 67,000 plumbers of sewers. When the act changes
and we get all the private sewers we are going to inherit overnight
another 40,000 plumbers. It is going to be big money and what
the Committee has to remember is that when we get that we have
not records of those sewers, no information on how they were built
and whether they were built to any acceptable standard. Most of
the individuals who carry out maintenance on them at the moment
are small franchise companies who turn up, clear blockages and
leave again. It will be quite a challenge.
Mr Wray: We are actually very
supportive of the idea. That is not to diminish the practical
and the funding issues associated with it, but we heard earlier
on the discussion around riparian law and at the moment our industry
has to deal with an issue where a customer calls with a very serious
issue of a blocked sewer and the nature of the conversation is
to first of all establish when the house was built to determine
whether or not it might be our responsibility. From the perspective
of serving consumers, from the perspective of maintaining good
health standards for sanitation, that is ludicrous so it is a
very good idea and we strongly support the concept of sewer adoption
into one agency. However, as my colleagues were saying, we have
to go through this very carefully to understand the nature of
those assets and what it will take to bring them up to the required
standard and then maintain them. In short it will be a huge insurance
policy for all householders.
Q387 Dr Strang:
Recognising there is a role for a small rural housing development,
am I right in saying that it is only satisfactory if the reed
bed does not go continuously into a stream or a river; a reed
bed that was adjacent to a running river would be ruled out presumably
because of the risk of pollution. That is my first question. Secondly,
are people actually artificially creating reed beds?
Mr Aylard: The first thing is
that they can go continuously into a river or stream provided
that the standard of treatment that is provided by the reed bed
is sufficient to meet the Environment Agency's discharge standards
so it has to be very carefully designed and monitored. And yes,
there are people who design reed beds on this scale commercially
in this country and abroad.
Can I just try to probe, particularly with reference to a city
like London, one of the things that I am totally unclear about
is just how much capacity have we got in the sewer system? We
have in previous inquiries had discussions about the state of
the sewers and the investment that may have to be made to upgrade
them, but luckily when they put the Victorian sewers in they seemed
to put a fair amount of spare capacity in. I would be interested
if one had a sort of uniformed rainfall over London can you tell
me at what level and for how long it has to rain before the sewers
fill up? In other words, they are absolutely full, they cannot
cope, they cannot discharge into wherever they go to? I am not
certain how bad the problem is.
Mr Collington: I think the honest
answer to that question is that it varies depending on the type
of event, whether it is a high tide or low tide in the Thames,
how long it rains for and what the pluvial conditions would be.
Let me try to relieve you of this variable nature of your response.
If we said, bearing in mind that tides run on a 12 hour in and
12 hour out, that over a 24 hour period there were three or four
hours of the kind of intense rain that may be associated with
an extreme weather event in a tide in situation in London, when
do you reach full? How many inches of rain have to fall?
Mr Collington: Most of the time
we can cope with three, four, five, six inches of rain for 45
minutes to an hour continuously. When it gets beyond an hour of
continuous rain and there are five or six inches of rain then
the sewerage system starts to struggle. If you look at 20 July
we had three or four hours of continuous rain; we have six to
seven inches in places and we had areas of London where the system
could not cope. Most of the major barrels of sewer that run underneath
London are nine foot in diameter; they tend to run east to west
across the city. There are large pumping stations that run along
the River Thames to pump out the sewerage system in times of extreme
weather and there are a number of overflows from the sewerage
system that act like pressure relief valves on the system to spill
sewerage into the Thames. That is the way the Victorian system
is designed. We are in the process at the moment of building a
large super sewer which will take 14 or 15 years to complete which
will take away those overflows and provide a storage system in
the base of the river for Thames' sewerage system. We are blessed
by the legacy of the Victorian system.
If we are looking at the show stopper issue flooding wise for
the centre of Londonlet us leave the Thames Valley slightly
outthe impression I get from what you were saying is that
if you carry on with your super sewer you can pretty well cope
with the types of event that you have described. If we turn it
into the one in so many years event, what kind of event are we
talking about that you are trying to cope with?
Mr Collington: The type of events
that we are funded for by Ofwat are anything up to one in 20 year
rainfall return period. Ofwat do not fund companies to deal with
anything beyond that.
If we go back to the July event; what was that in so many years?
Mr Collington: In the rural areas
that was a one in 150 year storm. In parts of London it was over
one in 100 years.
So if London were hit by a one in 150 year event you could not
Mr Collington: There are parts
of London that will cope; there are parts that struggle to cope.
Those are areas where we experience flooding at the moment.
You mentioned river side pumping stations and one of the issues
that came out of Gloucestershire was the question of the vulnerability
of infrastructure. I would be interested to know in a capital
city like London how vulnerable is the infrastructure. Obviously
in terms of the level of investment that you have to sustain to
keep the capital city going, depending on what you want to sustain
depends on how big a bill Thames Water payers have to bear. I
think it is that scenario which I find difficult to cope with,
to understand levels of investment versus levels of protection
Mr Aylard: I think it would be
quite rare to get the same level of rainfall across the whole
city. We tend to get these one in 150 bursts which are very, very
localised. Sometimes they will hit an area with a network that
can cope and sometimes they hit an area that cannot. Part of the
problem is that in those circumstances you cannot get the water
away quickly enough and that is why it floods. We are doing a
very detailed update with all our resilience work using the Environment
Agency's flood risk data. We are looking first of all at the likelihood
of flooding happening; secondly, what the impact would be on our
operations, on our customers, on other infrastructure in the area
(places like Heathrow for instance) and then at the cost benefit
analysis of that. That will all form part of our strategic business
plan that goes to Ofwat in 2009. You can be reassured that we
are looking again at all this.
If it as localised as you suggest, do you sort of take one mile
square areas and say that if that kind of one in 150 year event
occurred here what do you think might happen?
Mr Collington: We look at rainfall
data in one kilometre squares and we look at critical assets and
then we have drainage area plans which basically come down to
one kilometre squares.
So at the end of this exercise you would be able to present to
your shareholders and to Ofwat and to the public a menu which
says that if we want this degree of protection it is going to
cost that much in these locations. Is it going to work like that?
Mr Aylard: Broadly speaking yes.
I can give you an example from the 20 July flooding. Our Grimsbury
water treatment works was flooded to a depth of about six feet.
We knew that Grimsbury was liable to flooding; we had put in place
a one in 50 year scheme some years ago which consisted of a large
band around the site. We are also working with the Environment
Agency to design a one in 100 year scheme but what we got was
a one in 150 years. At that point we fell back on the contingency
arrangement for re-zoning the network and making sure that our
customers could be supplied from other works. There is a whole
series of things to try to reduce the risk to customers, starting
with physical measures and going down to re-zoning and ultimately
How does Severn Trent undertake similar scenario playing that
we have just heard about from Thames?
Mr Wray: In very much the same
way. We have the area drainage plans, we review those on a regular
basis and keep track, from the best of our knowledge from the
local authorities, where developments are going to take place,
how much capacity we have (we have run hydraulic modelling for
each of those areas and we try to predict where we are going to
see the capacity constraints). What we then do is point our investment
to those areas. For instance, this year we are completing major
sewerage capacity schemes in places like Leamington, Kenilworth,
Hinckly so we are keeping a constant review on the networks for
where that capacity constraint may fall and trying to stay ahead
of that with building that capacity into the network.
Do you think from your respective companies' points of view, bearing
in mind that the impact of extreme weather events are very unpredictablethey
may well be associated with the global phenomenon of climate changethat
it is still right for the water charge payers in each of the areas
that you respectively serve to bear the full cost of dealing with
the impact of these matters or do you think there is any merit
in looking at the collective sharing of perhaps an element of
extreme weather event expense on a national basis?
Mr Wray: My personal view is that
whilst there are still a lot of shades of opinion on climate change
it is undeniable. Actually that is the stance we take as the company
and that is embodied in our strategic direction statement. Coupled
with that, certainly through the events of Gloucestershire despite
the magnificent mobilisation that we have heard about from all
of the agencies and customers, we have just gone through a period
where we now have to deal with a paradigm shift in our thinking
of what is acceptable risk. In the short term I think there are
absolutely things that we can do and should do that inform our
plans. In the long term I think there is potentially a huge investment
burden required and we have to figure that out, how much of that
comes from the consumer directly and how much of that, if any,
comes from taxation. The one thing that is clear and not well
understood about our sector is that every year for Severn Trent
since the year of privatisationand I do not think any other
company is different to thisthe net investment in progressing
the infrastructure and dealing with the quality standards is far
greater than the actual profit made in the year. That is likely
to be the case for at least the next 20 years because of the need
to continue with the modernisation of the networks. Unfortunately
that cost burden will fall. I think it needs to fall in such a
way that consumers have sufficient information and transparency
to be able to comment on what they deem is the rate at which we
do that; what is affordable at any point in time.
Mr Aylard: I very much agree with
Mr Collington: I think the key
thing for meand it was mentioned in the previous sessionis
that unless we actually take an integrated approach to this we
are not going to solve the problem. There are areas of Kensington
and Chelsea that flooded in July this year; they also flooded
in severe wet weather events in 2004 and 2005. I know the answer
to the problem for that area in London is to build a huge sewer
and to take the sewage to the Counter's Creek, but there is no
way the river could cope with that. Therefore, if I solve the
problem for the residents of Kensington and Chelsea I just move
it somewhere else in London. Unless the Environment Agency and
the companies and the local authorities work together to solve
these problems, all we are going to do is shift the problem from
one place to another.
You would be very popular if you shifted Kensington and Chelsea
to certain places; there would be a bit of a riot there.
Mr Collington: The cost is huge.
For that one scheme we have estimated the cost to be £90
Mr Aylard: It is about half a
million pounds per property that would be helped by the scheme.
You could always turn Chelsea's pitch into a sort of SUDS; that
is a possibility. Anyway, before we get too many flights of fancy
let us move onto the Civil Contingencies Act 2004. In terms of
business continuity plans perhaps you could just describe to us
what your duties are under that Act. I gather that, under what
is described as the Security and Emergency Measures Direction,
that puts a requirement on you to keep under review and revise
your emergency plans and to ensure that you have the provision
to maintain essential water supply and wastewater at all times.
How do you do it? In the case of South West Water you could not
quite do that really through pipes because you had a bit of a
problem. My friend Mr Drew will come onto the Mythe Valley but
perhaps you could comment on these overall powers and how you
adhere to your legal requirements.
Mr Wray: For Severn Trent Water
we have a whole range of responses to that which run not only
to maintaining alternative supplieswhich we do through
provision of bowers and bottled water (I will talk more about
Mythe and Gloucester in a moment)but also through a whole
range of measures not just for the interruption of supplies which
can be from a break in the distribution because of civil activities
going onstreet works of some formright the way through
to disruption of supply such as, on a river intake, dealing with
pollution coming down the river which is the source of water.
Unfortunately we do live in a society where there are agencies
who would seek to do damage to things so there are a whole range
of contingencies that we have to make available there. In response
to those we go to great lengths to diversify supply on the networks
to provide multiple supplies, to physically protect sites and
assets and, in the event of loss of supply, the ability to make
alternative supplies available. The issue that we had this last
summer was that we were dealing with an event of a magnitude completely
outwith any experience, not just of Severn Trent, but on a scale
anywhere in the industry. That presented us with huge problems
which were dutifully overcome with the all agency support that
we had and has presented us with a huge number of lessons which
we are now working our way through and sharing them as widely
as we can such that everybody can benefit from that work.