Memorandum submitted by Yorkshire Water
(FL 122)
1. INTRODUCTION
1.1 Many thanks for the opportunity to contribute
to your inquiry into the flooding which occurred in our region
in June 2007. Before providing a detailed analysis of the flooding,
we would like to make the following observations:
— We would like to pay tribute to our
colleagues whose efforts throughout the flooding event meant that
we maintained the clean water supply to the region and that we
could respond rapidly and effectively to flooding incidents.
— The flooding in Yorkshire was caused
by significant and unprecedented rainfall and, as the Secretary
of State at DEFRA has stated, no system could have coped.
— Our sewerage and pumping infrastructure
was filled to capacity in parts of the region and overwhelmed
by the severity of the storms and the concentration of the rainfall.
We believe our infrastructure performed well in what were exceptional
circumstances.
— Like others, we are anxious to understand
if there could have been better planning and coordination between
the relevant agencies and to explore whether we can help to mitigate
some of the future risks by improving our infrastructure as part
of the multi-agency approaches being undertaken across the region.
— In order to facilitate an inter-agency
approach, there may have to be statutory changes to the responsibilities
of the parties including water companies, the Environment Agency,
land drainage boards and local authorities.
1.2 This memorandum is divided into the
following areas:
— An overview of Yorkshire Water
— Analysis of the rainfall in June
— Emergency and contingency planning
— Maintaining the clean water supply
— Our statutory responsibilities
1.3 We would be happy to answer any questions
prompted by this document and would be happy to appear before
the Committee.
2. OVERVIEW OF
YORKSHIRE WATER
2.1 Yorkshire Water is a water and sewerage
company and serves the area comprising the historic county of
Yorkshire.
2.2 Serving around 5 million people, we
supply 1.2 billion litres of clean water daily and we directly
employ 2,200 colleagues. We also work in partnership with a number
of service partners to invest in and maintain our water and waste
water network. Our current investment plan, agreed with our economic
regulator in 2004 and known as AMP4, equates to us spending £1
million on the region's water infrastructure daily.
2.3 We have been named "Utility of
the Year" by our peers in the utility sector for the last
three years and have been in the top two of Ofwat's league table
for operational and customer service for the last two years.
Ofwat has also identified Yorkshire Water as the most efficient
water company which they regulate.
3. ANALYSIS OF
THE RAINFALL
IN JUNE
3.1 River and surface water flooding during
June 2007 was the result of exceptional rainfall events on 15
and 25 June. Data published by the Met Office on 26 July shows
that May to July 2007 were the wettest months since records began
in 1766. In June, over 103.1 mm of rain fell in Fylingdales,
North Yorkshire. Our water gauges show that the storms in Hull
were at least a "1 in 151" year rainfall event.
3.2 The Hull Independent Review Body state
in their interim report that the Geography Department at the University
of Hull shows that rainfall on 25 June was heavy and sustained
with rainfall intensities of over 6mm an hour from 8 am to 5 pm.
They concluded that it was highly likely that many areas of Hull
were already significantly saturated on 25 June.
4. EMERGENCY
AND CONTINGENCY
PLANNING
4.1 On 12 June, the Met Office warned that
unseasonable rainfall may lead to flooding in Yorkshire and the
Midlands. On 15 June, exceptionally heavy and prolonged rainfall
impacted the region leading to widespread flooding.
4.2 We established Core Incident Management
Teams (CIMT) at our Regional Operational Control Centre (ROCC)
in Bradford. We had teams dealing with the clean and waste water
sides of our business and our liaison with the Gold and Silver
commands at Doncaster, Sheffield, Rotherham and Hull was managed
through these teams.
4.3 Establishing incident management teams
early meant that we were well-placed to deal with incidents as
they arose. It also gave the emergency command teams a clear
single point of contact with the company and with colleagues who
were empowered to make decisions.
4.4 Managing the event from the centre also
ensured that we were able to take a region-wide approach and could
ensure that company resources were focussed in the right place,
at the right time.
4.5 The incident at Ulley Dam put tremendous
pressure on temporary water pumping resources in the region.
Whilst we do have reserve pumping capacity available for emergencies,
it was difficult to source additional capacity until that situation
was resolved.
5. MAINTAINING
THE CLEAN
WATER SUPPLY—EMERGENCY
RESPONSE
5.1 Early in the incident, it was clear
that supporting the effort to shore-up Ulley Dam was the regional
priority. The reservoir, owned by Rotherham Council, was in danger
of collapse threatening the major industrial and utility infrastructure
further down the valley.
5.2 We immediately released colleagues with
reservoir safety expertise to support and advise the Council on
managing this incident and we identified our assets which were
within the potential flood inundation area and made arrangements
to isolate vulnerable sections of pipework.
5.3 This prompted us to undertake a proactive
programme of visiting our own reservoirs to ensure the integrity
of those structures. Whilst we were confident that the risk was
low due to our proactive reservoir asset planning approach, we
adopted a precautionary approach and colleagues twice daily walked
the parameter of those reservoirs we judged to be most at risk
to carry out visual inspections.
5.4 We also managed and monitored the impact
of the flood water on our water treatment works. There were two
clear priorities; firstly, ensuring that the water treatment works
themselves were not inundated with water and secondly, keeping
the system under positive pressure as this is essential to the
integrity of the system and therefore the quality of the water.
5.5 Most of our water treatment works are
located at areas higher than the areas they supply. This makes
economic sense because it minimises the requirement to pump the
clean water to customers and it also protects against flooding.
This meant that the risk of inundation was low. Our river abstraction
works are obviously more vulnerable to flooding and we did experience
extremely high river levels at Elvington, Loftsome Bridge and
Tophill Low. However these works did not flood internally and
continued to operate.
5.6 A bigger concern was the possible loss
of power to the works. Treating and pumping water is an energy
intensive activity and any loss of power would have resulted in
a loss of pressure, leading to possible inundation and therefore
corruption of clean water quality.
5.7 The immediate issue was the loss of
a National Grid supply point which meant there was a drop in capacity
in the Sheffield region. Yorkshire Electricity Distribution Limited
(YEDL) had to manage a situation where there was not enough power
but also where energy usage was very unpredictable. The closure
of businesses due to the flooding meant that their requirement
predictions, based on existing demand curves, were not reliable.
5.8 Rather than risk a loss of energy supply
to our water treatment works and water pumping stations, we moved
to on-site generation. All of our water treatment works have
stand-by emergency generation which we supplemented with more
generators at key assets, including water pumping stations.
We pulled together teams of three people, one from field operations,
one for asset management and an electrical and mechanical manager,
and they visited each water treatment site and ensured that there
was a robust energy supply.
5.9 We were then able to advise YEDL that
we would not be drawing power from the grid which released more
capacity for other users in the region. A win-win situation—whilst
switching to onsite generation was undertaken primarily to secure
our treatment works doing so assisted YEDL in managing their energy
demand.
5.10 We stayed on stand-by generation for
about a week after which we were able to reconnect to the grid.
5.11 The final issue was the management
of other physical assets. The Highways Agency advised us, for
example, that a trunk main which serves around 150k customer was
exposed. Water from the River Don had caused a landslide which
exposed the main and made it vulnerable. We developed an engineering
solution to shore-up the bank thereby protecting not only the
trunk main but also the road and other utility services which
ran alongside it and put this is in place within two days.
5.12 Throughout the flooding event, we did
not have any water quality incidents. This is to the credit of
our colleagues who literally worked around the clock to ensure
that the supply was maintained. Had it been lost, this terrible
event would have been a true catastrophe.
5.13 We lost supply from one water treatment
works, Ewden in Sheffield. We were able to maintain supplies
by using connections to alternative water treatment works and
to our grid.
6. MAINTAINING
THE CLEAN
WATER SUPPLY—PLANNING
FOR RESILIENCE
6.1 Our water supply network has high levels
of interconnectivity, giving high levels of resilience.
6.2 Designed to resolve the problems faced
by the Company in the drought on 1996, our water grid now means
that for around 95% of our customers we can switch to an alternative
water supply should their usual supply be lost.
6.3 Modelling of our system predicts that
our systems can maintain supplies for several days even with the
loss of more than one low level water treatment works. During
this period we would have time to manage down demand and put in
place further emergency measures.
6.4 We believe that our approach to network
development and the flexibility this gives us in terms of resilience
planning is industry-leading. However we will review the position
regarding those limited areas not connected to the grid to assess
the costs and benefits of building further resilience into the
system.
7. SEWER FLOODING
7.1 The unprecedented rainfall led to significant
flooding in the region which impacted differently in South Yorkshire,
the East Riding of Yorkshire, Selby and Hull.
7.2 South Yorkshire
7.2.1 In South Yorkshire, the high levels
of rainfall led to river flooding. Our waste water treatment
works tend to be located close to rivers so, as the Rivers Don,
Rother and Dearne and their tributaries overtopped, many of our
treatment works were overwhelmed by the flood water. In some
cases, colleagues were stranded at the works by flood water.
Our waste water treatment works at Blackburn Meadows near Meadowhall,
which serves Sheffield, was under 10 feet of water on Monday 25
June.
7.2.2 During high rainfall, Yorkshire Water
pumps screened but untreated flows directly into the river. This
is undertaken under a strict consents regime agreed with the Environment
Agency. When we cannot pump water into rivers, because the rivers
themselves are overflowing, water backs up the system. This is
known as fluvial flooding. In these situations, customers may
see water coming back from the sewer system into streets.
7.2.3 Once the water had subsided, we could
begin to pump flows into the river again and in South Yorkshire
the flood waters quickly subsided.
7.2.4 The exception was Toll Bar in Doncaster,
where due to its low elevation, flood waters remained for a number
of days. Our pumping stations at Toll Bar worked throughout this
flooding event. We actively monitored the pumping stations and
were well placed to respond if they too became overwhelmed.
7.3 Selby and the East Riding of Yorkshire
7.3.1 In the rural areas of the East Riding
of Yorkshire and some parts of Selby, the rainfall did cause our
network to become overwhelmed and customers did experience extensive
surface water flooding.
7.3.2 In these cases, the areas affected
recovered quickly. Once it stopped raining, the sewers and drains
could cope with the flows and the water ran away.
7.3.3 The East Riding is very flat and low
lying therefore excessive rainfall will not drain away quickly.
The land drainage facilities, maintained by others, and the water
courses maintained by the Environment Agency interlink with the
sewerage network maintained by Yorkshire Water.
7.3.4 The East Riding of Yorkshire is also
dependent on drains to discharge flood waters. The high levels
of the Burstwick Drain prevented emergency discharge of flood
waters from the sewerage system and in the West, the Setting Dyke
and the Cottingham Drain overflowed into the sewerage system.
These dykes and drains are not owned or maintained by Yorkshire
Water.
7.3.5 The management of flows from the drainage
system into the Humber is the responsibility of the Environment
Agency. We are dependent on this drainage system as sewers also
discharge into it. We would like to work with them to better
understand these issues and if possible to develop remedies that
allow our networks to discharge effectively rather than backing
up, causing our sewers to overflow.
7.3.6 Some flooding occurred to the west
of Hull and affected towns including Hessle and Anlaby in the
East Riding. The incidents of flooding in these areas are connected
to what happened in the city of Hull and this is covered in the
next section.
7.4 Hull
7.4.1 The City of Hull is below high-tide
level and is therefore dependent on an effective sewerage, drainage
and water pumping system to remove surface water from the city.
As with the East Riding, our sewers interconnect with water courses
and land drains operated by others.
7.4.2 Many of our assets in the city of
Hull were overwhelmed by the sheer volume of rain fall on 25 June,
including our waste water treatment works at North Ferriby and
Saltend. Despite being 2ft under water, our works continued to
operate at Saltend. This works serves the ½ million people
in the city.
7.4.3 Our major pumping stations at East
and West Hull on the A63 worked to capacity throughout the storm
event, pumping over 50,000 litres of water per second into the
Humber.
7.4.4 On Tuesday morning (26 June), we were
alerted to a surface water pumping station failure at Bransholme
in the north of the city. The foul water pumping station at this
site continued to operate throughout the storm event.
7.4.5 The pumping station, which takes surface
water from the Bransholme Estate, was fully operational at the
time of the storms but eventually was flooded like the rest of
the estate by the exceptional rainfall causing the pumps to fail.
7.4.6 We responded quickly and some pumping
capacity was restored by Tuesday evening and we were able to source
additional standby pumps to restore full capacity by Friday. To
further assist in the clean-up, we have utilised additional capacity.
The pumping station is now being repaired.
7.4.7 We have contributed to an inquiry
commissioned by the Leader of Hull City Council into the flooding.
We are currently developing a detailed response to the interim
report published by the Inquiry.
7.4.8 We have also commissioned engineers
Arups to carry out a study of the sewerage network in Hull. We
want to reassure our customers in that city that we take the concerns
they have expressed very seriously.
7.4.9 We believe that a substantial multi-agency
review of drainage arrangements in Hull will be required. The
Environment Agency, Hull City Council and Yorkshire Water will
all need to contribute to this and will need to be prepared to
fund any resulting investment requirements.
8. RECOVERY
8.1 The flooding had a massive impact on
YW assets and operations with over 30 waste water treatment works,
including Blackburn Meadows, and over 100 sewage pumping stations
being flooded. The initial emergency response secured a return
to normal operational performance albeit with the support of temporary
equipment. The next reinstatement phase is now underway which
will return the assets to their pre-floods status so that long
term operational performance can be sustained. A dedicated Reinstatement
Team involving both YW and our Partners is now well established
and the programme to reinstate the YW assets in both the South
and East of our region is going to plan. The scale of the work
is such that it take until December 2008 to complete the programme.
8.2 Our contractors, Drainsaid worked around
the clock to help with the clear-up on those homes directly impacted
by flooding from our sewers.
8.3 We were able to support Severn Trent's
water business when their operational area was impacted by high
rainfall in July. We contacted them and provided thirty operational
colleagues to work under their direction. Our colleagues worked
with Severn Trent for twelve days. We also provided tankers,
continuous supply trailers, bottled water and bowsers.
9. STATUTORY
RESPONSIBILITIES
9.1 It is apparent in discussions we have
had with our customers and our other stakeholders that there is
some confusion over the roles and responsibilities of various
agencies with regard to river flooding and the drainage and sewerage
networks. There is also confusion about the role of water companies
in planning decisions where there is new development.
9.2 Water companies, local authorities and
the Environment Agency all have very clearly areas of responsibilities
and these are defined in statute. These provide the framework
within which the different agency responses to the flooding event
can be understood. Our remit regarding sewerage and drainage
is very narrowly defined. Section 94 of the Water Industry Act
1991, states:
"It shall be the duty of every sewerage
undertaker to provide, improve and extend such a system of public
sewers (whether inside its area or elsewhere) and so to cleanse
and maintain those sewers as to ensure that that area is and continues
to be effectually drained".
Sewers are elsewhere defined as drains serving
premises, not open land. Water companies are not therefore liable
for surface water and rainfall management.
9.3 Water companies are subject to strict
economic regulation and the Regulator will only allow companies
to undertake and therefore charge our customers for activities
which are defined in these regulations with regard to the sewerage
network.
9.4 Water companies are not statutory consultees
for new planning applications. If we are approached by a developer
or the local council, we can request conditions which the approving
authority may attach to the permission when granted. We also
have no powers to monitor that recommendations we have made are
implemented.
9.5 We are obliged to offer all new developments
the right to connect into the public sewerage system under S.104
of the Water Industry Act.
9.6 Such regulations may have to be reviewed
as a result of this summer's flooding event.
Yorkshire Water
September 2007
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