Improvements in reservoir construction, operation and maintenance : proceedings of the 14th conference of the British Dam Society at the University of Durham from 6 to 9 September 2006

428 Pages·2006·182.417 MB·English

by  Henry Hewlett (ed.)

The British Dam Society
Improvements in reservoir construction,
operation and maintenance
Proceedings of the 14th Conference of the British Dam Society at the
University of Durham from 6 to 9 September 2006.
Edited by Henry Hewlett
thomastelford
Conference organised by the British Dam Society, www.britishdams.org
Organising committee: Jon Green (Chairman), Henry Hewlett, Andy Hughes, Mark
Morris, Andrew Pepper and Jim Prentice.
In addition to members of the organising committee, the following personnel kindly
assisted with the review of papers: Alan Brown, Ian Hope, Jim Millmore, Mark Noble
and Paul Tedd.
Cover photograph: Kielder Dam at sunset, courtesy of Northumbrian Water
Published by Thomas Telford Publishing, Thomas Telford Ltd, 1 Heron Quay, London E14 4JD.
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First published 2006
Also available from Thomas Telford Books
Long-term benefits and performance dams. British Dam Society. ISBN 07277 3268 4
A guide to the Reservoirs Act 1975. DETR and ICE. ISBN 07277 2851 2
Reservoir Engineering. Guidelines for practice. E. Gosschalk. ISBN 07277 3099 1
Risk and uncertainty in dam safety. D N Hartford and G B Baecher. ISBN 07277 3270 6
A catalogue record for this book is available from the British Library
ISBN: 0 7277 3470 9
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Preface
This book contains the proceedings of the 14th Conference of the British Dam Society,
Improvements in reservoir construction, operation and maintenance, held at the
University of Durham in September 2006.
There are 36 papers covering a wide variety of issues. Recent changes to reservoir
legislation in England and Wales relating to enforcement of the Reservoirs Act 1975 and
the requirement to prepare flood plans, and the introduction of the Controlled Activities
Regulations in Scotland, are discussed. Following the upgrading of many spillways in
the last 30 years, internal erosion is increasingly seen as the greatest threat to UK
reservoirs, and a number of methods for the early detection of internal erosion are
described. The Interim Guide to Quantitative Risk Assessment of UK Reservoirs was
introduced at the Society's 2004 Conference, and there are reports on feedback in its use.
Hydrological and hydraulic issues covered include: a study into the effect of changes in
weir crest coefficient with head; computer modelling of the operational systems of
reservoirs, and developments in dam break modelling. Various schemes and studies in
Portugal, India, Kazakhstan, Georgia and Egypt are also covered. Grouting works at two
reservoirs are described and there is a paper on the desiccation assessment of the puddle
clay cores at several reservoirs. Various other works to refurbish and rehabilitate dams
are described and illustrated.
The conference included the presentation of the biennial Geoffrey Binnie Lecture by
Chris Binnie. The 2006 Lecture, entitled 'Dams, responding to society's needs' is
published in the Society's journal Dams and Reservoirs.
Contents
1. Implementation and operation of UK reservoir legislation
Reservoir safety - are things improving?
A HUGHES 3
Development of the requirements for flood plans under the Reservoirs Act 1975
(as amended)
A J BROWN and J D GOSDEN 13
A new incident reporting system for UK dams
A L WARREN and I M HOPE 26
Reservoir hazard analysis and flood mapping for contingency planning
JC ACKERS, RVPETHER and FRTARRANT 37
Impact of the Controlled Activities Regulations on dam construction,
maintenance and operation in Scotland
CWBERRYandKMHBARR 47
2. Hydraulics and hydrology
Improved reservoir level assessment through the mathematical modelling
of weir crest coefficients
P MASON, K DEMPSTER and J POWELL 61
Yuvacik Dam: improvements to dam operation utilizing an integrated
atmospheric-hydrological model
T GEZGIN, A UNAL SORMAN, A SENSOY and A ARDA SORMAN 72
Water management at Dinorwig pumped-storage power station
MI BAILES and O P WILLIAMS 84
Boscastle and North Cornwall floods, August 2004: implications for dam
engineers
R BETTESS and V BAIN 94
Reconstruction of the Znojmo Dam - practical application of hydraulic research
V STARA, M SPANO and J SULC 106
3. Internal erosion
Identifying leakage paths in earthen embankments
V KOFOED, J MONTGOMERY and K GARDINER 119
Is internal erosion dectable?
J DORNSTADTER, D DUTTON, A FABRITIUS and P HEIDINGER 129
Leakage investigations at Lower Carno Dam
A ROWLAND and A POWELL 144
Comparison of methods used to determine the probability of failure due to
internal erosion in embankment dams
M EDDLESTON and I C CARTER 154
In search of the perfect geotextile/geocomposite filter for retro-fitting old
embankment dams
M EDDLESTON, H TAYLOR, N ROBINSON and A BINNS 165
4. Planning and design
Wave surcharge on long narrow reservoirs — a reality check
A KIRBY and K DEMPSTER 183
The Kielder Water Scheme: the last of its kind?
C S MCCULLOCH 196
Glendoe hydroelectric scheme, optimisation and dam selection
M SEATON and J SAWYER 211
Assiut Barrage, to rehabilitate or to rebuild
T J F HILL 224
5. Risk assessment and dam break analysis
Preliminary feedback on the Interim Guide to Quantitative Risk Assessment
for UK reservoirs, 2004
A J BROWN and J D GOSDEN 239
Quantitative Risk Assessment in practice
J D GOSDEN and D DUTTON 251
FLOODsite (Integrated Flood Risk Analysis and Management Methodologies)
- research relevant to the dams industry?
M W MORRIS and P G SAMUELS 261
Numerical tools for dam break risk assessment: validation and application
to a larges complex of dams
B J DEWALS, S ERPICUM, P ARCHAMBEAU, S DETREMBLEUR
andMPIROTTON 271
Failure impact assessment of a mine site flood levee in Australia
R PETHER 283
6. Refurbishment, construction and maintenance
Refurbishing and upgrading old spillway gate installations
JLEWIN, GMBALLARDandPTO 295
Investigation and rehabilitation of Chardara Dam spillway
J H MELDRUM 304
Application of modern grouting technology to remedial works on dams
A K HUGHES and C T KETTLE 315
Emergency underwater rehabilitation of the Poti Main Diversion Weir, Georgia
L SPASIC-GRIL 330
Barrow Compensation Reservoir grouting works
A WARREN, C HUNT and M ATYEO 345
Reservoir safety and refurbishment works at Severn Trent Water's Howden,
Derwent and Linacre Reservoirs
S A ROBERTSON 355
The management of siltation at Hillsborough Dam, Tobago
D A BRUGGEMANN and J D GOSDEN 368
Desiccation assessment in puddle clay cores
A KILBY and A RIDLEY 381
The failure of the Mostiste embankment dam
J RIHA and J SVANCARA 391
Construction of three RCC dams forming part of the Ghatghar pumped storage
project in India
V C SHELKE,MRH DUNSTAN, JLHINKS andTZELENKA 404
Lightweight fill in dam remediation - a case study
KMHBARR 412
The influence of inspection and monitoring on the phased construction of the
Barragem de Cerro do Lobo
M CAMBRIDGE and M OLIVEIRA TOSCANO 419
1. Implementation and operation of UK reservoir Legislation
Reservoir Safety - Are things improving ?
DR ANDY HUGHES, Director of Dams & Water Resources, Atkins
SYNOPSIS
This paper seeks to look at reservoir safety over the years and how some
things have changed. The paper suggests that there have been some
significant improvements in reservoir safety such as the creation of the
Supervising Engineer role, the creation of the single Enforcement Agency,
but it also suggests that there are a number of areas where improvements
have not been made and in fact the situation might be getting worse. The
paper suggests some areas for improvements but also invites readers to think
whether the issues raised apply to their organizations and situation in a hope
that they will then bring about change.
HISTORICAL BACKGROUND
Reservoir safety on the whole in the UK has been driven by the legislative
framework which has been developed with time. The Reservoirs (Safety
Provisions) Act, 1930 bought in the regular and frequent inspection of dams
by Panel Engineers and was prompted by a couple of failures, which caused
loss of life - notably the failures in the Conway Valley at Eigiau and Coedty
Dams, and Skelmorlie on the Forth of Clyde. This set the definition of a
'large raised reservoir' as a reservoir containing 5 million gallons above the
level of the natural ground, adjoining the reservoir.
As a result of a number of further incidents and failures, particularly in
Europe, an ad-hoc committee of the Institution of Civil Engineers was set up
to review the legislation, and this committee made a number of
recommendations which eventually resulted in the Reservoirs Act 1975.
This Act brought in a number of new features, the main ones being the
creation of the role of the Supervising Engineer, the creation of the
Enforcement Authority and thus enforcement of recommendations, and
registration of reservoirs.
The UK has had no dam failures resulting in loss of life since 1925 although
there have been a number of failures, mainly of small dams and there have
been a large number of incidents/accidents - some more serious than others
Improvements in reservoir construction, operation and maintenance, Thomas Telford, London, 2006, 3—12
4 IMPROVEMENTS IN RESERVOIRS
- some would say that the UK has been fortunate in not having failures
resulting in loss of life since 1925.
In 2006 the question I wish to pose is 'have we made progress in the field of
reservoir safety since 1925 - what have we achieved in 81 years?'
In looking for the answer to this question there are a number of issues which
I have considered and present in this paper;
THE SUPERVISING ENGINEER
There is no doubt in my mind that creation of the role of the Supervising
Engineer has been a useful addition to improve reservoir safety. The
Supervising Engineers have become the 'eyes and ears' of the Inspecting
Engineers and certainly in recent years there seem to have been more
inspections called for under Section 10 (2)(d) - by the Supervising
Engineer.
It has been recently suggested in some quarters that the Reservoirs
Committee has raised its standards, resulting in a number of failures of
candidates seeking appointment and/or re-appointment to the Supervising
Engineers Panel. Many of those failures have been cited as people who were
nearing the end of their career, who had a low level of activity and/or could
not display the commitment to continued professional development (CPD)
or do not have confined space training.
In my personal opinion a number of people who have not been re-appointed
are Supervising Engineers especially if one remembers that the original idea
of the group formulating the legislation was that the Supervising Engineer
would be the Reservoir Keeper at the site. However, the role of the
Supervising Engineer is changing and I believe the role of the Supervising
Engineer will become more onerous with time. Already, the Supervising
Engineers are 'responsible at all times' when there is not a Construction
Engineer and as time progresses are likely to get more involved with
monitoring progress with recommendations in the interests of safety and
perhaps calling for inspections as conditions deteriorate within the 10 year
period set by the Inspecting Engineer. They are also likely to get more
involved with the checking, exercising and even rehearsal of Flood Plans.
THE ENFORCEMENT AUTHORITY
The creation of an Enforcement Authority was undoubtedly an improvement
and important addition to the legislation in the form of the Reservoirs Act
1975. Unfortunately, in the 1980's and 90's, the Enforcement Authority role
was vested in 168 organisations, and still remains the responsibility of 32
different organizations in Scotland. However, the Scottish Executive has