7.4.3 UK legislation: the Reservoirs Act (1975)
UK legislation was first introduced in 1930, following two small but catas-
trophic failures in 1925. The legislative framework underwriting dam
safety is now provided by the Reservoirs Act (HMSO, 1975) and is
explained in detail in an associated guide (ICE, 2000). A review of the
British system cannot be divorced from an appreciation of the circum-
stances in which it is required to function. Population densities and reser-
voir numbers in the UK are relatively high, particularly in the traditional
heavy industrial regions. As a compounding factor, 83% of the 2650 UK
dams subject to statutory legislation are earthfill embankments, and are
therefore inherently more susceptible to certain risks, e.g. flood overtop-
ping. The median age of the dam population is also relatively high at an
estimated 100–105 years, and over 30% of dams are owned by small firms
or by individuals. The composition of the UK dam population is discussed
in Tedd, Skinner and Charles (2000). In terms of downstream hazard it is
reported that some 75% of the reservoirs subject to statutory legislation
are Category A or B (Table 4.1 and ICE, 1996), i.e. they are considered to
represent a significant risk to life and/or would cause extensive damage to
property in the event of breaching. Reviews of the incidence of deteriora-
tion and remedial works on British dams have been published by Moffat
(1982) and Charles (1986).
The essential features of the UK Reservoirs Act can be summarized
as follows.
- The legislation applies to all ‘raised reservoirs’ with a storage capac-
ity in excess of 25 000 m^3 above the natural level of any part of the
adjacent land.
- The owner is entirely responsible in law for maintaining a reservoir
in safe condition.
- The registration of reservoirs and enforcement of the Act in England
and Wales are the responsibility of the Environment Agency. In
Scotland, the responsibility is currently (2006) vested in the regional
authorities, but will transfer to the Scottish Environmental Protec-
tion Agency. (The Reservoirs Act is not applicable to Northern
Ireland).
- The design and construction of new reservoirs, and the statutory
inspection or major alteration of existing reservoirs, must be carried
out under the direction of a nominated Panel Engineer, i.e. a senior
engineer appointed to a statutory specialist panel.
- Statutory inspections by a Panel Engineer are required at intervals
not exceeding 10 years.
- Owners are required to nominate a Supervising Engineer, qualified
and empanelled as such under the Act, to maintain continuity of
supervision and surveillance between statutory inspections.
308 DAM SAFETY: INSTRUMENTATION AND SURVEILLANCE
