Geography Reference
In-Depth Information
raw water quality did not have the expected
characteristics.
Within the process, all critical parameters need
to be monitored using reliable, well-designed and
easily maintained instruments. The data from such
monitoring systems, when properly analysed, will
allow process modification and management and
decision support such that the expected levels of
service can be delivered at a reasonable cost, with
failure risk minimised to customers, shareholders
and regulators.
This area of the industry, reliant as it is on
communication and remote-monitoring
technology, will benefit most from shared
understandings of common problems. To gather
data in a manner that will allow its effective
integration will require a setting of protocols and
standards for data collection, aggregation and
transmission. It will also require a changed
approach by university researchers away from the
groupings of like-minded researchers (say several
hydrologists from different institutions) to
innovative and 'unnatural' groupings (water
engineer, electronics engineer, psychologist,
groundwater hydrologist, archaeologist and global
positioning system analyst) if, for example, ground
penetrating radar (GPR) is to be developed for
tracing leakage in the water industry effectively.
repairs, standpipes or back siphoning. Even when
the pipes remain whole, dead-ends lead to
chlorine decay, stagnation and sedimentation.
Lining material leaches from mains and from lead
supply pipes. Research is needed both on technical
and procedural improvements to pipe renovation
and usage to minimise contaminant ingress and
on the determination of environmental factors
(age, soils and topography) that influence pipe
failure. Geophysical techniques such as GPR offer
powerful techniques to locate pipes and leakage,
particularly for deep non-metallic pipes, where
correlators are less effective.
Pressures, quantity and flow (PQF) rates are
subject to standards set by the Ofwat director
general but have been the subject of intense
political interest because it is claimed that pressure
reduction is being used as a tool to achieve the
leakage reductions required by the government.
PQF has to be sufficient not only to cope with
peak demand but also to cope in the face of
planned and unplanned (mains failures)
interruptions and exceptional fire-fighting
requirements. This presents network management
and network information modelling and
simulation opportunities as well as contingency
planning improvement to deal with emergency
supplies in the event of failure.
Leakage
is
the most topical characteristic of
distribution systems. Leakage occurs as two types:
(1) a steady background leakage due mainly to
poor jointing and corrosion; and (2) intermittent
failures due to ground movement often induced
by weather and traffic and third party damage
from other companies having or installing
underground assets such as cable TV. In practice,
there is a gradation between these two types.
Bursts, particularly if unseen by the public and of
a magnitude that does not interfere with supply
to an area, will be viewed as part of the
background. Leakage has become a political issue,
and leakage targets have been set by the
government as part of John Prescott's 'Water Task
Force' (see Table 10.1).
All systems leak (e.g. schools have truants and
electricity is lost as heat in transmission), and in
most situations this is accepted. The setting of
DISTRIBUTION SYSTEMS
The distribution system connects the customer to
the treatment works through a structure consisting
of a dendritic pipe network incorporating service
reservoirs. The system has to deliver, efficiently, a
reliable and secure supply of water of an
appropriate quantity, quality, flow and pressure. In
the UK, many of these systems are well over 100
years old. They have been added to as a response
to urban growth rather than as planned
engineering extensions. Both the age and the
nature of the development present the water
manager with serious challenges.
Water leaves the treatment works at near
pharmaceutical quality. It is contaminated when
the system integrity is impaired through leakage,
