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TECHNICAL PAPER
Geomembrane sealing systems for dams: ICOLD Bulletin 135
Alberto Scuero1 • Gabriella Vaschetti1
Received: 3 May 2017 / Accepted: 2 June 2017 / Published online: 20 June 2017
� Springer International Publishing AG 2017
Abstract The paper presents the contents of the latest
bulletin published by the International Commission on
Large Dams (ICOLD) on the subject of geomembranes as
sealing systems for dams. Bulletin 135, published in 2010,
is an updating and expansion of ICOLD Bulletins 38,
published in 1981, and 78, published in 1991. Bulletin 135
has been prepared, under the aegis of the ICOLD Com-
mittee on Materials for Fill Dams, by the ad-hoc European
Working Group for geomembranes and geosynthetics as
facing materials, composed by experts from nine European
countries, with external contribution from USA. Different
competences were covered by the group, which included
geomembrane scientists, dam designers, geomembrane
systems designers, dam owners, and geomembrane spe-
cialist contractors. The bulletin is composed of 9 chapters,
in total 464 pages for the English and the French versions.
The paper outlines the history of the constitution of the
working group, the preparation of the database on
geomembrane systems in dams all over the world, dis-
cusses the topics covered by each chapter, and gives some
statistics based on the database. Some case histories men-
tioned in the Bulletin, and recent developments, are also
presented.
Keywords Geomembrane � Waterproofing � Dams � PVC �ICOLD
Introduction and background
The use of geomembranes in hydraulic structures has more
than half-century history: geomembranes were first used in
canals immediately after the Second World War, in the
research and field experimentation carried out by the US
Bureau of Reclamation on various types of canal linings
since 1946. In dams the use of geomembranes started in
1959 at Contrada Sabetta fill dam in Italy. The first
applications were made in construction of new fill dams,
which being intrinsically pervious need a separate com-
ponent to provide imperviousness. The concept of using
synthetic impervious geomembranes instead than conven-
tional impervious materials such as clay, concrete or
asphalt concrete, certainly derived, among other consider-
ations, from the good performance of embedded polyvinyl
chloride (PVC) waterstops in the huge number of concrete
dams worldwide that rely on their use to stop water infil-
tration at joints. A geomembrane system on the upstream
face of a dam can be considered, from a conceptual point of
view, as one wide waterstop sealed at the abutments and
bottom.
In the early 1970s, the use of geomembranes was
extended to the rehabilitation of old concrete dams, and in
the early 1980s to the waterproofing of new Roller Com-
pacted Concrete (RCC) dams. At present geomembranes
are adopted all over the world to waterproof all types of old
and new dams (concrete gravity dams, buttress dams, arch
dams, multiple arch dams, rockfill dams with concrete
facing, rockfill dams with asphalt facing, earthfill dams,
tailings dams, RCC dams), and practically all types of
This paper was selected from GeoMEast 2017–Sustainable Civil
Infrastructures: Innovative Infrastructure Geotechnology.
& Gabriella Vaschetti
Alberto Scuero
1 Carpi Tech, Balerna, Switzerland
123
Innov. Infrastruct. Solut. (2017) 2:29
DOI 10.1007/s41062-017-0089-0
hydraulic structures (canals, hydraulic tunnels, surge
shafts, pumped storage reservoirs, forebay reservoirs,
underground tanks, etc.). The issue of the use of
geomembranes on dams, which are among the most
demanding and critical hydraulic structures, has been
addressed by ICOLD, the International Commission on
Large Dams, in two theme bulletins.
Bulletin 38 (1981)
Bulletin 38, ‘‘Use of thin membranes in fill dams’’ [1], was
published in 1981. Bulletin 38 defined geomembranes as a
‘‘thin product with a thickness from one to a few mil-
limetres, constituted of a flexible watertight material…[that]… may be prefabricated at works and then trans-
ported to the site, or prepared and positioned directly on the
site (in situ)’’; it considered a cover layer mandatory for a
geomembrane system; and recommended a height of 30 m,
and a surface of modest dimensions. Increasing the limit
height to 40 m was deemed to be based on foreseen future
improvements in technique and materials.
Bulletin 78 (1991)
As the use of geomembranes increased and gradually
extended to the rehabilitation of all types of existing dams,
and to waterproofing of the new Roller Compacted Concrete
damswhich began being built in the early 1980s, the need for
an updating of the bulletin was felt. In 1991 ICOLD pub-
lished a new theme bulletin, Bulletin 78, ‘‘Watertight
geomembranes for dams—State of the art’’ [2]. Bulletin 78
considers geomembranes an established technique for new
construction and rehabilitation of fill dams, as an emerging
application for rehabilitation of concrete and masonry dams,
and as ‘‘Future prospects’’ in application to new RCC dams;
the cover layer is no more considered necessary; and con-
cerning the limit height ‘‘There is no reason to recommend a
specific height limitation on the use of geomembranes in
embankment dams’’.
After 1991, the use of geomembranes to waterproof new
dams and to restore imperviousness in old dams further
increased. Europe, where the majority of dams are old, was
one of the main users and developers of geomembrane
systems. In European countries the need for increased
information on current practice and trends was more deeply
felt. In 1993, during a symposium on dam rehabilitation
organised by the ICOLD French National Committee in
Chambery, a European Working Group for geomembranes
and geosynthetics as facing materials was established, with
the mission of investigating the behaviour of geomembrane
systems installed in previous times, and of ascertaining and
assessing the most recent developments in new projects.
The Group was formed by members of the ICOLD
National Committees of Austria, France, Germany, Italy,
Portugal, Switzerland, and the United Kingdom, and by
experts from the Czech Republic, France, Italy, and Spain.
All competences were covered: the group included
geomembrane scientists, dam designers, geomembrane
systems designers, dam owners, and geomembrane spe-
cialist contractors. The decision was taken to create a
database collecting the most relevant information on
geomembrane systems already in service on dams. The
next chapter details how the database was compiled. In the
years that followed, the database included[80 European
dams, and then it was gradually extended to include case
histories also from countries outside Europe.
The start and completion process of Bulletin 135
At the ICOLD Executive Meeting in Antalya in 1999, the
ICOLD Committee onMaterials for Fill Dams, under whose
aegis Bulletins 38 and 78 had been published, discussed the
data collected by the working group and decided to amplify
the information and make it available to the international
dam community. The Committee extended the working
group to include worldwide leading experts in the field of
geomembranes, and gave it an official mandate to prepare a
new bulletin on geomembranes, addressing design, manu-
facturing, installation, quality control and contractual
aspects, and to extend the database to the whole world.
Database
The database was implemented starting from some data
already included in Bulletins 38 and 78, and from the initial
database created by circulating through the members of the
working group among owners of dams the technical form
elaborated for this purpose. The technical form is a 6-pages
document consisting of:
• Section A:Main information, containing data on the dam
(characteristics and service conditions), type of geomem-
brane and characteristics of the geomembrane system,
and the owner’s comments on efficiency, durability,
technical and economical effectiveness of the system
• Section B: Additional information, mainly adding data
on features of geomembrane system, and on geomem-
brane installation, quality control and costs.
To implement incomplete forms, or to collect data of
dams for which forms were not available from the owner or
its consultants, data from international literature (Pro-
ceedings of ICOLD Congresses, Executive Meetings,
Conferences of National Committees, Conferences of
ASDSO, the US American Society of Dam Safety Offi-
cials, articles in specialised publications such as Reservoirs
29 Page 2 of 17 Innov. Infrastruct. Solut. (2017) 2:29
123
and Dam of the UK National Committee, Bulletin of the
Australian National Committee), and personal communi-
cations by designers and University professors, were used.
Work method
After the contents of the bulletin had been discussed and
agreed by all members in the first plenary meetings, smaller
groupswere created toprepare thevarious chapters in function
of their competence. Periodical meetings were used so that all
or most of the members of the group could peruse, make
comments and refine the parts prepared by the smaller groups.
The findings of the database served as permanent comparison
and also to evaluate evolutions of the geomembrane sealing
systems if any. Drafts of completed chapters were circulated
internally to gather comments from all members.
When the first complete draft in English was ready, it was
submitted to the Committee on Materials for Fill Dams,
during the Executive Meeting of 2001. The final version in
English was approved by the Committee in 2005.
The French National Committee requested that the 209
pages of the approved final English version be translated in
French and the bulletin published in both languages. The
final French version was completed in 2008. More than
1 year was required for final revision and approval. Bul-
letin 135 was published in 2010, with the title
‘‘Geomembrane Sealing Systems for Dams–Design prin-
ciples and review of experience’’. In total 464 pages,
inclusive of 17 pages of terminology and 14 pages of
bibliography and most common standards.
Bulletin 135
The foreword of the bulletin [3], written by Mr. Marulanda,
Chairman of the Committee on Materials for Fill Dams, is
well in the context of the history of geomembranes sealing
systems in dams.
Foreword of the bulletin
The first edition of this Bulletin was issued in 1981 as Bull.
38 (*). It was a precise, detailed technical guide with
comprehensive references: types of membranes along with
their features were reviewed as well as theoretical and
actual strains involved; procedures to be developed were
detailed with examples.
In 1991, the new Bulletin 78, ‘‘Watertight Geomem-
branes for Dams. State of The Art’’ (**) cited 70 dams
incorporating geomembranes and it focused on new and
improved materials which in the meanwhile became
available and on the experience gained which has resulted
in a better understanding of their use and in advanced
engineering skills in this field so that they have been used
in higher dams than before. The Bulletin 78 dealt with new
areas such as enhancing the water retaining performance of
other facings, repairing old gravity dams and the deterio-
rated upstream concrete facings of fill dams. Finally, Bul-
letin 78 reported new ideas regarding drainage, supporting
layer and protective covering and geomembranes which
were at that time (1990) under consideration for the
upstream facings to roller compacted concrete dams.
This new edition in 2010 cites 280 dams and updates the
data and recommendations of the first two 38 and 78
Bulletins. It reviews the new information and practices that
have appeared in the meantime, which include application
of geomembrane as the only watertight element in fill dams
(Bovilla, Albania, 91 m, 1996), in RCC dams (Miel 1,
Colombia, 188 m, 2002), as external joints on RCC dams
(Porce II, Colombia, 118 m, 2000), as underwater repair of
dams on gravity dams (Lost Creek, USA, 36 m,1997) and
on RCC dams (Platanovryssi, Greece, 95 m, 2002).
This new Bulletin also deals with application of
geomembranes for dams affected by AAR (Pracana, Por-
tugal, 65 m, 1992). The Bulletin reports about sealing of
defective joints and cracks in the upstream face of CFRDs
by strips of geomembranes mechanically fastened (Straw-
berry, USA, 101 m, 2002).
The 280 dams incorporating geomembranes cited in this
new Bulletin are 188 fill and 91 concrete ? RCC (?1 of
unknown type). Out of the 280 dams 48 are in USA, 47 in
China, 42 in France, 35 in Italy, 10 in Spain and inGermany, 9
inAustria, 6 in theCzechRepublic, 5 inPortugal, 4 inBulgaria
and in UK, 2 in Belgium, Cyprus, Romania, Slovakia and
Switzerland, 5 scattered in other European countries. Europe
and USA account for[67% of the total (188 dams). Because
of the large experience gained in Europe, this revision was
prepared by the EuropeanWorking Group onGeomembranes
as Facing Materials for dams, appointed by the International
Commission on Large Dams, with the assistance of some
experts from USA. This bulletin conveys to the reader a real
worldwide experience on use of geomembranes, with the
oldest now dating more than 45 years and still in service. The
authors deserve our warmest appreciation, and in particular
Alberto Scuero, co-ordinator of the Group, Gabriella
Vaschetti, Secretary, and some members of the Group, in
alphabetical order, Blanco, Cazzuffi, Girard, Koerner,
Lefranc, Millmore, Schewe, Sembenelli, Vale.
A.M. MARULANDA
Chairman,
Committee on Materials for Fill Dams
(*) Report prepared by R. Corda and H. Grassinger,
members of the Committee on Materials for Fill Dams,
with the assistance of K. Rienossl (Austrian National
Committee) and J. Combelles, J. Couprie, P. Huot, V. Lelu,
D. Loudiere and P. Paccard (French National Committee).
Innov. Infrastruct. Solut. (2017) 2:29 Page 3 of 17 29
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(**) Report prepared by R. Corda, member of the
Committee on Materials for Fill Dams, with the assistance
of G. Degoutte and C. Bernhard (CEMAGREF, France), L.
O. Timblin and W. R. Morrisson (USCOLD) and D. Caz-
zuffi (ENEL, Italy).
Contents of the bulletin
The bulletin has been structured in 9 chapters and 3
appendixes:
• Chapter 1: is an introduction to geosynthetics, to their
classification in several families according to their
function, and in general to their field of application
• Chapter 2: describes classification and characteristics of
the various types of geomembranes, and discusses
materials specifications and testing
• Chapter 3: discusses the loads and stresses to which
geomembranes are exposed, criteria and recommenda-
tions for design, construction and operation. The loads
and stresses relevant to a particular type of dam are
addressed in the relevant dedicated chapters.
• Chapter 4: discusses application of geomembranes in
construction of new fill dams, application of geomem-
branes to repair of asphalt-concrete sealing facings,
bituminous geomembrane facings, and concrete facings
in CFRD
• Chapter 5: discusses application of geomembranes to
repair of concrete, shotcrete and masonry facings of
gravity dams and arch dams. The chapter addresses
repair in the dry and underwater
• Chapter 6: discusses application of geomembranes to
RCC dams as watertight upstream facing in new
construction, and as repair of existing RCC dams
• Chapter 7: discusses special applications as watertight
element at joints and cracks, and as an underwater
repair measure
• Chapter 8: dedicated to quality control
• Chapter 9: gives recommendations for specification for
design, supply and construction, including guidance to
technical contents of contracts
• Appendix 1: the database, related to the ICOLD
definition of ‘‘large dam’’.
• Appendix 2: a list of geomembrane technology terms
and definitions (according to IGS–International
Geosynthetics Society)
• Appendix 3: bibliographic references and references on
testing standards.
The following paragraphs state, more formally, the
contents of the nine chapters and of the three Appendixes,
explaining the main issues for of each chapter.
Chapters 1 and 2: introduction and materials
The chapters address all geomembranes, i.e. materials
prefabricated in a factory, either in relatively thin contin-
uous polymeric sheets (polymeric geomembranes, with a
large predominance of PVC geomembranes), or by
impregnation of geotextiles with bituminous materials
(bituminous geomembranes). The geomembranes consid-
ered are factory-made polymeric and bituminous
geomembranes. In situ impregnated geotextiles and
sprayed liners based on polyurethane and polypropylene
resins, which are closer to the family of the resins and less
and less frequently used, are not subject of the bulletin. The
few existing examples have notwithstanding been included
in the database.
The chapters discuss materials’ composition, configu-
ration, supply, seaming, testing, durability and ageing, with
some statistics for each type of geomembrane (Table 1).
Overall, polymeric geomembranes account for[91% of
the total, out of which about 60% are PVC. Bituminous
geomembranes have been used only on 20 dams, of which
17 in covered position.
Chapter 3: loads acting on the GSS
This chapter describes the stresses and constraints to which
geomembranes are exposed when used as sealing element
in dams: mechanical, physical, chemical, biological and
other types of attacks. It offers criteria and recommenda-
tions to consider in the design, construction and operation
of dams with having a geomembrane as water barrier.
Identification and relevant and comprehensive characteri-
zation of all the stresses to which the geomembrane sealing
system will be submitted is essential to ensure the success
of the project.
Chapter 4: fill dams
This chapter deals with applications of geomembranes in
fill dams, where geomembranes have been used in 60% of
cases in new construction, in 40% as rehabilitation measure
of asphalt concrete facings and of concrete facings
(CFRDs). Approximately in 90% of dams, the geomem-
brane was installed in upstream position, to minimise
uplifts and uncontrolled water presence in the dam body,
improving stability and safety.
Generally speaking, the application of a PVC
geomembrane system in new fill dams has the significant
advantage that, being the geomembrane very deformable
(typically[230%), it can accommodate without breaking
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the not negligible movements that are typical of this type of
dam, especially at the junctions between the deformable
dam body and the rigid concrete structures (e.g. spillways,
intakes, plinth), and the settlements that may still occur
after impoundment. New fill dams with geomembrane
systems are behaving quite well. In new construction, the
chapter discusses the various configurations: upstream
exposed, upstream partially or totally covered, and internal
position, including the cases of heightening of existing
dams, and giving examples for each configuration.
At publication of Bulletin 135, the most recent face
anchorage technique for upstream exposed geomembranes
was by seaming the PVC composite geomembrane liner to
PVC anchor strips embedded in porous concrete curbs
against which the fill was placed.
Sar Cheshmeh tailings dam raising was the first
embankment dam adopting this type of face anchorage
system. Sar Cheshmeh existing tailings storage in Iran,
owned by National Copper Industries Co., included a 75 m
high main embankment consisting of an inclined clay core
as impervious element, and of outer colluvial gravel shells.
The production escalation required a set up comprising a
39.5 m high and 1000 m long downstream raise to the
main embankment, in four separate stages, of which IIB
and IIC have been completed so far. Stability analysis
showed that the seismic stability of a raised clay core was
not sufficient, due to the geometry of the raising. Further-
more, no suitable clay based materials were available at
site. ATC Williams, designers of the dam raising, consid-
ered as alternative solutions an asphaltic core, an upstream
bituminous membrane, and polymeric geomembranes. An
upstream exposed PVC Geomembrane Facing Rockfill
Dam (GFRD) was selected because of superior safety in
respect to earthquakes. ATC Williams deemed the GFRD
system would be the most stable, efficient and buildable
arrangement.
The finishing layer of the dam is made with extruded
porous concrete curbs illustrated in the schemes of Fig. 1.
The face anchorage for the waterproofing liner is the
patented method with PVC anchor strips discussed above.
As the embankment and curbs were being raised, the PVC
strips were nailed to the curbs and then permanently
anchored by the fill compacted against the curbs. Over-
lapping PCV strips were joined by heat-seaming. The
procedure is shown in Fig. 3. The PVC geocomposite used
for the anchor strips and for the liner is SIBELON� CNT
4400, consisting of a 3 mm thick PVC geomembrane, heat-
bonded during manufacturing to a 500 g/m2 non-woven
polypropylene geotextile (Fig. 2).
The PVC strips heat-welded at the overlap, form con-
tinuous anchor lines. The SIBELON� geocomposite liner
sheets were then deployed from the crest, after having been
secured at top by a stainless steel batten strip on a con-
ventional concrete curb. After cleaning the PVC anchor
lines, the PVC geocomposite sheets were temporarily
anchored at the crest of the first stage, stage IIB, and then
unrolled down the slope (Fig. 4 on left). The PVC geo-
composite sheets were heat-welded to the PVC anchor
strips (Fig. 4 on right). Adjoining PVC geocomposite
sheets were watertight heat-welded at overlapping, as
shown in Fig. 4 at bottom.
The bottom seal of stage IIB was made by embedding
the PVC geocomposite in a trench excavated in the clay
core of the existing dam, and then backfilled with clay
(Fig. 5 on left). The bottom perimeter seal at the concrete
plinth of the abutments is mechanical, referred to as the tie-
down type. In tie-down seals, watertightness against water
in pressure is attained by compressing the PVC geocom-
posite unto the concrete with flat stainless steel batten strips
secured by stainless steel anchor rods embedded using
chemical glass anchoring capsules at regular spacing.
Smoothing epoxy resin, rubber gaskets, stainless steel bat
Table 1 (Table 3 in Bulletin
135)-Synthetic materials more
frequently employed as
geomembranes
Type Basic material Abbreviation
Thermoplastic Chlorinated polyethylene
Ethylene–vinyl acetate copolymer
Polyethylene
Polypropylene
Polyvinyl chloride
CPE
EVA/C
PEa
PP
PVC
Thermoplastic rubbers Chlorosulfonated polyethylene
Ethylene–propylene copolymer
CSPE
E/P
Thermo-set Polyisobutylene
Chloroprene rubber
Ethylene-propylene diene monomer
Butyl rubber
Nytrile rubber
PIB
CR
EPDM
IIR
NBR
a Within the group shown, polyethylene and polypropylene are collectively called polyolefins
Innov. Infrastruct. Solut. (2017) 2:29 Page 5 of 17 29
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ten strips and splice plates achieve even adequate com-
pression necessary for watertightness, as extensively
described in international literature (Fig. 5 on right).
The intermediate seal between stage IIB and stage IIC is
made by watertight welding the geocomposite of the upper
stage on the geocomposite lower stage, and covering the
Fig. 1 Upstream exposed geomembrane with PVC anchor strips (Carpi patent)
Fig. 2 Deployment of
waterproofing geocomposite
sheets on the PVC anchor strips
Fig. 3 PVC anchor strips embedded in curbs
29 Page 6 of 17 Innov. Infrastruct. Solut. (2017) 2:29
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weld with a PVC geomembrane strip. The seal top of stage
IIC is made by embedding the geocomposite in a trench
then ballasted with conventional concrete as shown in
Fig. 6.
Stage IIB and staged IIC raisings reached 20 m of
height. Total surface was 38,500 m2. Installation of the
waterproofing system took 14 weeks in total (Fig. 7).
Fig. 4 Deployment and heat-welding of geocomposite sheets on PVC anchor lines, and heat-welding of adjacent sheets
Fig. 5 Bottom perimeter seal-embedded type (left) and the tie-down type (right)
Fig. 6 Intermediate seal between stage IIB and stage IIC (left) and top perimeter seal at stage IIC (right)
Innov. Infrastruct. Solut. (2017) 2:29 Page 7 of 17 29
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More dams have now been constructed with the same
system. A recent (2015/2016) example is Nam Ou VI 88 m
high rockfill dam, which is part of the Nam Ou VI
Hydropower Project in Lao PDR, and the highest GFRD in
Laos. The PVC geocomposite selected to ensure long-term
watertightness in exposed position is SIBELON� CNT
5250, consisting of a 3.5 mm thick PVC geomembrane,
heat-bonded during manufacturing to a 700 g/m2 non-wo-
ven polypropylene geotextile. The system was the same of
Sar Cheshmeh. The dam body and its waterproofing system
were constructed in three separate stages: stage 1 from the
bottom of the excavation at El. 427 m to El. 472.1 m, stage
2 to from El. 472.1 m to El. 512.1 m, and stage 3, com-
prising a 3 m high parapet wall, to reach El. 515.0 m.
Installation of the geomembrane system of stage 1 was
completed in 24 days for 13,700 m2 of upstream water
barrier; installation of the geomembrane system of stage 2
was completed in 28 days, for about 23,000 m2 of
upstream water barrier. In total, 52 days to construct a
watertight upstream facing of almost 37,000 m2, a fraction
of what a concrete facing would have required (Fig. 8).
An outstanding application of the same technology is
ongoing at Las Bambas copper mine currently developed in
Peru. Tailings from the mine processing plant are pumped
to a Tailings Storage Dam (TD) located within a broad
valley and formed by a large Tailings Retaining Embank-
ment on the southern and eastern sides. The TD will con-
tain all tailings generated from processing operations, all
bleed water released from the deposited tailings, and all
water runoff from the TD catchment. For mine start-up
purposes, the TD will be the primary water storage for the
commissioning of the concentrator plant. The TD will
continue to be utilized as water storage throughout the
operating life of the mine. The Tailings Retaining
Embankment, therefore, needs to be a water retaining
embankment, and is being built from rockfill and water-
proofed with an exposed PVC geocomposite, to construct a
GFRD.
The Tailings Retaining Embankment is being raised in
stages, and when completed will be 230 m high. Stage 1A
has an approximate height of 58 m, and total surface lined
is 39,767 m2; stage 1B has raised the embankment to a
maximum height of 88 m, and total surface lined is
138,129 m2. After completion of stage 1B the Carpi crews
were placed in standby until construction of the embank-
ment embedding the anchor strips in the curbs from
Fig. 7 Upstream exposed geomembrane at Sar Cheshmeh tailings dam in Iran
Fig. 8 Stage 1: stage 1 ? stage 2 waterproofing system completed in 52 days
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elevation 4020 m to elevation 4050 m was completed,
around middle of November. Carpi started to install the
geocomposite system of this stage on 19 November 2016.
Installation is at present ongoing. Total surface to be lined
in this stage is 172,512 m2. The installation of the
geomembrane has already reached a height of 118 m from
the foundation (Fig. 9).
New patented technologies are recently being used for
upstream geomembrane systems in new fill dams, which
were not available at the time of publication of the bulletin.
Such technologies include face anchorage of the
geocomposite by deep grouted anchors, such as adopted at
Filiatrinos hardfill dam, and face anchorage by PVC anchor
strips embedded in trenches, such as adopted at Bulga
earthfill dam. The same systems were adopted at some of
the 18 Waters Saving Basins of the Panama Canal
Expansion. See Fig. 10.
Design aspects such as the characteristics and stability of
the various layers, the anchorage at boundaries, the
anchorage over the dam face, and installation techniques, are
analysed. Specific aspects for rehabilitation are the anchor-
age systems, designed depending on the type and strength of
Fig. 9 Stage 1: Las Bambas tailings dam at stage 1, and the dam pictured in November 2016
Fig. 10 Upstream exposed geomembrane anchored by deep grouted anchors (Filiatrinos hardfill dam, Greece 2015, left) and by trenches (Bulga
earth dam, Australia 2016, right, Panama Canal Expansion Water Saving Basins, bottom)
Innov. Infrastruct. Solut. (2017) 2:29 Page 9 of 17 29
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the existing facing (asphalt concrete or concrete). The var-
ious aspects to consider when deciding if to place a cover
layer on the geomembrane in a new fill dam are discussed, as
the possibility of damaging the geomembrane when placing
the cover was well known. The chapter discusses also
available alternatives for geomembranes in central position,
of which no photos were available at that time. See Fig. 11.
The rehabilitation of fill dams with concrete facing
(CFRD) and with asphalt concrete facing (ACFRD) is also
addressed. The exposed system (conceptually the same
described in ‘‘Chapter 5: concrete and masonry dams’’),
and the covered system are described.
Chapter 5: concrete and masonry dams
In concrete and masonry dams, geomembranes have been
used for rehabilitation. Only in one case of partial appli-
cation at heel, the geomembrane was used since new
construction. Almost all concrete and masonry dams that
have used geomembranes for rehabilitation have been
waterproofed with the systems patented by Carpi. Perfor-
mance history of this system is at present approaching
40 years, and field results have proven its capability of
extracting and discharging water already permeating the
concrete, for example at Pracana dam, where the exposed
PVC geomembrane has helped slowing the alkali-aggre-
gate reaction. Both the cases that follow are reported in
Bulletin 135.
Pracana is a 65 m high buttress dam in a seismic and hot
region of Portugal, built between 1948 and 1951. Ano-
malies in the behaviour of the dam were evident since first
impoundment: cracks appeared at the upstream and
downstream faces, significant seepage and carbonation at
the downstream face were observed. Unsatisfactory per-
formance of local repairs required lowering the reservoir
level. In 1997 EDP, Electricidade de Portugal, became the
owner of the dam, and put the dam out of operation to
thoroughly investigate its behaviour, its conditions, the
causes of deterioration, and to develop a rehabilitation
plan. Investigations ascertained that among concurrent
causes of cracking (deficiency in construction techniques,
thermal variations of concrete during construction, differ-
ential settlements of not-consolidated foundations) were
also expansive phenomena of concrete. A major concern
was related to the critical scenario relevant to sliding
conditions along horizontal cracks, especially considering
the uplifts. Expansion of concrete was further investigated
and ascertained the presence of alkali-aggregate reactions,
which further activated by infiltration of water from the
reservoir. Restoring and granting long-term imperviousness
to the upstream face, and reducing the uplifts, were
mandatory.
The large rehabilitation and refurbishment works at the
dam included an upstream drained waterproofing
geomembrane, to stop water infiltration, to avoid that water
in pressure could act on the horizontal cracks, and to
deprive the dam of its water content; construction of a new
grouting plinth and of two sets of struts between buttresses
at the downstream face, to improve stability; treatment of
foundations, including execution of a new grout curtain;
construction of a new auxiliary spillway, to improve
behaviour and safety in respect to extreme floods, and of a
new water intake, and concrete treatment, consisting of
individual cement grouting for larger cracks and mass
grouting with epoxy resin for smaller cracks.
The exposed drained PVC geomembrane system was
installed in the dry season of 1992, concurrent with the
huge civil works. To enhance drainage capability a drai-
nage geonet was placed on the entire surface then covered
by the waterproofing geocomposite (Fig. 12 on left). The
drainage system was divided in 10 separate compartments
Fig. 11 Upstream covered geomembrane (Bovilla gravel dam, Albania 1996, left) and central zigzag geomembrane (Gibe III cofferdam,
Ethiopia 2009, right)
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for the water drained from the upstream face of the dam,
and a separate compartment for the water coming from
foundations.
At bottom, the perimeter seal was installed on the new
foundation plinth, achieving connection of the liner with
the new grout curtain, so that the water barrier is contin-
uous from crest down to deep impermeable foundations.
Watertight perimeter seals were placed also around intake
and outlets, and at the rails for operation of the gates.
The PVC geocomposite SIBELON� CNT 3750, con-
sisting of a 2.5 mm thick PVC geomembrane, heat-bonded
during manufacturing to a 500 g/m2 non-woven geotextile,
is anchored by Carpi patented tensioning profiles (Fig. 12
on right, an excerpt of ICOLD Bulletin 135), placed at
1.8 m spacing, and by a watertight perimeter seal of the tie-
down type already discussed. The regularising resin, rubber
gaskets and stainless steel splice plates allow achieving the
even compression that grants the watertightness.
The tensioning system is designed to maintain the liner
in a stable position, to tension it, avoiding formation of
slack areas and folds, and to keep it independent from the
dam face, allowing and facilitating drainage of water
between the dam and the geocomposite by creating an air
space between the upstream face of the dam and the
geocomposite.
The waterproofing system was installed in 5 months, for
a total of 7900 m2. Reported total leaks, from upstream
face and from foundations, are less than 0.34 l/s. Since
1992, in addition to monitoring the performance of the
geocomposite system and its effectiveness in respect to
leakage control, EDP has been monitoring the behaviour of
the dam, to ascertain the capability of the system to
dehydrate the dam body, reducing the water content feed-
ing the AAR. LNEC, the National Laboratory for Civil
Engineering, is in charge of studying the swelling reactions
through various measuring systems. The details of the
monitoring systems and of the findings of the study can be
found in the exhaustive paper presented by EDP at the 21st
Congress of ICOLD in Montreal (Liberal et al. [5]. In the
final conclusions of the paper, EDP reports that ‘‘A sig-
nificant gradual reduction of the swelling rate was observed
[omissis] and the concrete dam waterproofing may be
assumed to contribute for the reduction of the swelling
process’’ (Fig. 13).
In 2017, during the oral presentation made by EDP (S.
Domingo Matos) at CFBR (French Committee for Dams
and Reservoirs) it was announced that the installation of the
geomembrane has definitely almost stopped the reaction.
In masonry dams, the waterproofing system is similar to
the one adopted on concrete dams; the roughness of the
masonry generally requires installing a thick anti-puncture
geotextile under the geocomposite, and regularising with
mortar the surface where the perimeter seals are placed.
Kadamparai dam, owned by the Tamil Nadu Electricity
Board (TNEB), is an example. The dam is 67 m high and
478 m long, was completed in 1983, and is used as a forebay
reservoir to the 400 MW Kadamparai pumped-storage
scheme. From around 1995, seepage gradually began to
increase. Main seepage sources were deteriorated joints
between the stones of the masonry, cavities that had formed
in the masonry, joints between monoliths, and seepage
through the foundation rock. Over time seepage rates
increased dramatically, with a peak seepage of 38,000 l/min.
Since the conventional methods already adopted had failed
Fig. 12 Pracana buttress dam, Portugal 1992. The upstream face during rehabilitation and refurbishment works: from left to right, the new
intake, the black geonet covering the face, and the PVC geocomposite installed over the geonet. At right, the tensioning profiles
Innov. Infrastruct. Solut. (2017) 2:29 Page 11 of 17 29
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at Kadamparai, the final decision was to adopt an upstream
geomembrane; an international tender was floated, and the
waterproofing works started at site on January 17 2005.
The Carpi system at Kadamparai consists of an imper-
meable PVC geocomposite liner, mechanically fastened to
the dam body, tensioned and drained, according to the
patented solution with tensioning profiles. To mitigate the
roughness of the masonry, a 2000 g/m2 needle-punched
nonwoven anti-puncture geotextile was placed over the
masonry. The waterproofing liner is the same geocom-
posite installed at Pracana. As at Pracana, adjoining sheets
were vertically joined by heat welding. A double
mechanical seal at bottom, and separate drainage com-
partments for various areas of the upstream face and for the
area between the two bottom seals, provide accurate
monitoring of the efficiency of the system, implemented by
piezometers detecting if water is standing behind the geo-
composite, and by an optical fibre cable system that allows
locating the area of a leak if any (Fig. 14).
The whole system covering more than 17,300 m2
including the monitoring system was completed in
4 months, 6 weeks ahead of schedule. Total seepage has
been reduced from 38,000 l/m to about 100 l/m. It is more
than 10 years now still the measured leakage rate stands
around 100 l/m.
Rehabilitation in this type of dams is generally made on
the entire upstream face, but partial sealing systems have
been used to seal specific joints at heel or cut off wall
(Kolnbrein 200 m high arch dam and Schlegeis 131 m high
arch dam, both in Austria), or joints with failed joint sea-
lant (Vale do Rossim, Portugal). In recent times rehabili-
tation limited to most leaking areas, to meet budget
constraints or to stage construction according to available
funding, is also experienced.
Among the various design and installation aspects
addressed, the possibility of reducing uplift with a drained
system, and recent developments allowing underwater
repair of the entire upstream face.
Fig. 13 At left waterproofing works completed at Pracana dam. At right, the dam pictured in 2003, when the owner reports: ‘‘waterproofing may
be assumed to contribute for the reduction of the swelling process’’
Fig. 14 Kadamparai masonry dam, India 2005, pumped storage. The
installation of[17,000 m2 geomembrane system involved the use of
thick geotextile to cover the rough masonry face. Prior to installation,
the dam was leaking more than 38,000 l/m, after Carpi completed the
geomembrane installation leakage dropped to 100 l/m
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Chapter 6: RCC dams
Extensive construction of RCC dams started at the begin-
ning of the 1980s. The use of geomembranes in RCC dams
followed closely, in 1984. Since 2000, the use of
geomembranes has been extended from new construction
also to rehabilitation of RCC dams (entire face, leaking
sections, cracks, holes). Rehabilitation has been carried out
also underwater and is described in ‘‘Chapter 7: special
cases’’.
In RCC dams, geomembranes are used to waterproof the
entire upstream face, or as external waterstop for contrac-
tion joints or repair of cracks. Basically all dams have been
waterproofed with one of two available options: exposed
geomembrane or covered geomembrane, both patented.
The exposed system is an evolution of the system used
for rehabilitation, and it was first adopted at Riou France, in
1990. Outstanding examples reported in Bulletin 135 were
Miel I (Colombia 2002), at 188 m then the highest RCC
dam in the world, and Olivenhain, 97 m high,
1,036,736 m3, and highest RCC dam in USA, 2003.
Miel I is a straight gravity dam constructed in a narrow
gorge in Colombia. To meet contractual schedule, the
original design of an upstream face made of slip formed
reinforced concrete was changed to a drained exposed PVC
geomembrane system, placed on a 0.4 m thick zone of
grout enriched vibrated RCC. This double water shield was
considered necessary due to the height of the dam. The use
of grout enriched RCC allowed good compaction at the
dam face, assuring a good finishing of the upstream con-
crete surface.
The waterproofing liner is a geocomposite, consisting of
a PVC geomembrane laminated to a 500 g/m2 non-woven
polypropylene geotextile. In the lowest part of the dam,
from elevation 268 m to elevation 330 m, the PVC
geomembrane is 3 mm thick, from elevation 330 m to
elevation 450 m it is 2.5 mm thick. The entire upstream
face is 31,500 m2.
The geocomposite face anchorage is made by parallel
vertical tensioning profiles, placed at 3.70 m spacing.
Where the water head is higher, i.e. from elevation 268 to
358 m, the stainless steel profiles have a central rein-
forcement. The configuration was slightly different from
the one shown in Fig. 12 because, according to the state-of-
the-art at the beginning of the 2000s, the U-shaped com-
ponent of the tensioning profile assembly was attached to
the formwork and embedded in the 0.3 m high RCC lifts,
while in current projects this component is placed after the
RCC is completed, like in rehabilitation of concrete dams.
The second component of the tensioning profile assembly,
placed over the installed PVC geocomposite and connected
to the first component, secures and tensions the PVC liner
on the upstream face. The profiles are then waterproofed
with PVC cover strips, as shown at right in Fig. 15.
The integrated face drainage system behind the geo-
composite consists of the gap between the liner and the
dam face, of the geotextile laminated to the PVC
geomembrane, of the vertical conduits formed by the ten-
sioning profiles, of a peripheral collector embedded in the
RCC, of the transverse discharge pipes discharging into the
gallery, and of ventilation pipes assuring water flow at
ambient pressure. The drainage system is divided into 4
horizontal sections (compartments), each discharging in the
gallery located at its lower point. Each horizontal com-
partment is in turn divided into vertical compartments with
separate discharge. In total there are 45 separate compart-
ments that allow accurate monitoring of the behaviour of
the waterproofing system.
Construction of the grouting plinth was made following
placement of the RCC. A PVC geocomposite, placed over
the completed RCC lifts and over the natural excavation
rock, waterproofs the plinth. The liner waterproofing the
Fig. 15 Miel I RCC dam. Left: U-shaped profiles and drainage
collector attached to the formworks are embedded in the RCC.
Middle: U-shaped profiles after embedment appear as vertical
drainage grooves in the face of the dam. Right: tensioning profiles
are waterproofed with PVC cover strips
Innov. Infrastruct. Solut. (2017) 2:29 Page 13 of 17 29
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plinth is watertight connected to the liner waterproofing the
upstream face by a tie-down seal. This type of seal, tested
at 2.4 MPa, is placed also at crest, to resist water
overtopping.
In correspondence of the contraction joints, two layers
of sacrificial geocomposite provide support to the liner on
the joint. The PVC geocomposite was installed in 6 hori-
zontal sections. A movable railing system was used to
install the PVC waterproofing system concurrent and
independent of RCC activities. The railing system was
attached to the dam face at first at approximately 90 m
above foundation, and then moved to some 140 m above
foundation. The travelling platforms, from which all
activities were carried out, were suspended at the railing
system. Installation of the PVC geocomposite could thus be
carried out from the platforms while RCC placement was
ongoing above the railing system. Staged installation
allowed early impounding while the dam was still under
construction (Fig. 16).
Construction of the dam started in April 2000 and ended
in June 2002, in total 26 months. The change in design
allowed meeting the schedule, and saving several 10 mil-
lions US dollars, because of reduced content of cement,
faster completion, earlier power generation.
Olivenhain RCC dam in California is a conventional
gravity dam 788 m long and 97 m high. The dam, the
highest RCC dam in USA and first RCC dam built in the
highly seismic state of California, is a key element of the
Emergency Storage Project (ESP) of the San Diego County
Water Authority, owner of the dam. About 90% of water is
brought to San Diego from hundreds of miles away, and the
aqueducts cross several large active faults, including the
San Andreas Fault. The ESP will provide water to the San
Diego region in case of an interruption in water delivery
deriving from an earthquake or drought.
Evaluation of the alternatives for the upstream face,
considering the magnitude of design earthquake and the
critical function of the dam to provide water during an
emergency, placed emphasis on seismic stability and
seepage control. In a range of 1–3, these features were
assigned the maximum weighting factor of 3 (Kline et al.
[4]). Special consideration was also given to construction
sequence because the dam had to be fully operational
within a certain date.
In the stability analysis, the exposed geomembrane liner
and its face drainage system were considered two features
that would tend to reduce the uplift pressure. Furthermore,
if this uplift reduction features were to be damaged and
rendered inoperable during a large earthquake which would
damage the geomembrane, the effects of uplift pressures
would not be as critical, because it would take some time
for the pore pressure to increase, and by then the water
level would have been lowered according to the rules of the
California Division of Safety of Dams. The external
geomembrane system received the highest score among the
11 considered alternatives.
Shaping blocks and plinth are waterproofed with the
same geocomposite used for the upstream face, watertight
connected to the geocomposite of the upstream face with
the same seal used at Miel I. Also the face drainage system
is similar to the one adopted at Miel I, with the addition of
a drainage geonet installed on the RCC (Fig. 17 on left), to
enhance discharge capabilities should accidental damage
occur to the impervious geomembrane. Under the pressure
of the hydrostatic load the geonet will maintain high
transmissivity, no water will be able to migrate through lift
joints in the body of the dam, thus saturation levels and
pore pressures in the dam will be lowered, with beneficial
effects on the stability safety factors, and on the appearance
at the downstream face.
The PVC geocomposite, the same adopted in the higher
part of Miel I dam, is fastened by vertical tensioning pro-
files at 3.70 m spacing. The embedded profiles have been
designed larger than standard, to create larger vertical
Fig. 16 Left: installing the geocomposite in horizontal phases
concurrent with RCC placement reduced times for completion at
Miel I. Right: the geocomposite already installed in the lower sections
allowed impounding the reservoir and testing the machinery while
construction was still ongoing
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conduits and further enhance drainage transmission.
Stainless steel plates, 60 9 6 mm, placed every 40 cm
inside the profiles, avoid that the profiles deform under the
hydrostatic load. Each line of profiles discharges separately
into the gallery, and can be individually monitored. The-
oretically there is one compartment for each line, in prac-
tice since the area of influence of the vertical lines is not
watertight confined, some water of pertinence of one line
may still travel to the adjacent lines. The upstream face
has, therefore, been divided into 12 compartments, sepa-
rated by a vertical watertight seal, to allow defining the
area of the leak in case of damage.
The peripheral seals are made by compressing the
geocomposite with 80 9 8 mm flat stainless steel batten
strips. The seal is of the same type adopted at Miel I.
Waterproofing works were completed in 5 months. The
reservoir started filling on August 7, 2003. Concerning
resistance to seismic events: Olivenhain on June 16, 2004,
experienced a magnitude 5.2 earthquake, with reservoir
almost at full supply level. The event was centred about
60 miles SW of the dam site. Inspection was performed,
seepage rates were compared to those of the previous
inspection of June 1, 2004, and seepage was found to be
about the same, or smaller (Fig. 18).
RCC dams lined with PVC geomembranes typically
show insignificant seepage as compared to RCC dams
with conventional concrete facing. At Miel I, total leakage
at fully impounded reservoir is 2.0 l/s, mostly from abut-
ments [5]; Balambano 95 m high RCC dam, Indonesia,
exposed PVC system installed in 1999, has a total water
flow for all 6 box drains of the 15,490 m2 upstream face
varying from 0.012 l/s to a maximum of 0.965 l/s at full
supply level.
The covered PVC system was developed in USA, and
the first installation was made in 1984. The bulletin anal-
yses pros and cons of the two solutions, and critical aspects
of design and of installation techniques.
Chapter 7: special cases
Special applications are basically related to an external
waterstop system that can be installed since construction
(on contraction joints of RCC dams, or to allow partial
application at crucial locations). The system can also be
used to rehabilitate failing joints and cracks in concrete
facings (CFRDs, concrete and RCC dams), in the dry and
underwater.
Fig. 17 Olivenhain RCC dam, USA 2003. At left, drainage geonet is placed on the RCC to enhance drainage collection and discharge; at middle,
the PVC geocomposite is placed over the geonet; at right, the tensioning profile is connected to the profile embedded in the RCC
Fig. 18 The exposed PVC geocomposite system completed at Olivenhain RCC dam, USA 2003. At right, in 2004 Olivenhain, 97 m high,
sustained a magnitude 5.2 earthquake
Innov. Infrastruct. Solut. (2017) 2:29 Page 15 of 17 29
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The external waterstop system shown in Fig. 19, which
is patented, consists of:
• A support layer, installed over the completed RCC lifts,
which impedes the waterproofing liner from intruding
in the active joint at maximum opening of the joint
under the maximum water head. This component is
generally composed of one or more independent layers,
in function of the water head and anticipated move-
ments of the joints
• The waterproofing liner, a PVC geocomposite water-
tight anchored along the perimeter.
With[230% tri-dimensional elongation at break of the
PVC geomembrane, the external waterstop is more efficient
than a conventional embedded waterstop, elongation is free
over a larger width, bridging movements in the order of
several cm. Installation does not interfere with RCC place-
ment. Examples of new construction are Platanovryssi RCC
dam, Greece 1998, at 95 m the highest RCC dam in Europe,
and Porce II 118 m high RCC dam, Colombia 2000.
An outstanding example of special application is the
installation of a PVC geomembrane on the horizontal joint
between phase 1 and phase 2 face slabs at Karahnjukar
198 m high CFRD, where the same PVC geomembrane
had been installed on the toe wall in 2005. The PVC
geomembrane has the objective of waterproofing the hor-
izontal joint in case of potential cracking (Fig. 20).
Examples of repair are Dona Francisca RCC dam (63 m
high, Brazil, 2000, failing joints and cracks), Platanovryssi
RCC dam (the same system installed on contraction joints
during construction was used in 2002 to repair underwater
a crack) and Strawberry CFRD (50 m high, USA, failing
joints). In the last few years, the same system has been
adopted for underwater repair of cracks and failing joints in
concrete and RCC dams.
Chapters 8 and 9: quality control and guidanceon technical contents of contracts
Chapter 8 includes recommendations on Quality Control
and Quality Assurance at manufacturing, transport, and
installation. It discusses items to be addressed, type and
frequency of controls, and testing procedures.
Chapter 9 on technical contents of contracts provides
some guidelines on how procurement of geomembrane
Fig. 19 Scheme and example of external PVC waterstop installed during construction: Porce II RCC dam, Colombia 2000, 118 m high
Fig. 20 Example of special application: Karahnjukar, Iceland. In 2005 PVC geomembrane to waterproof the toe wall (left), in 2006 PVC
geomembrane to waterproof the horizontal joint of the 198 m high CFRD in case of potential cracking
29 Page 16 of 17 Innov. Infrastruct. Solut. (2017) 2:29
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systems for dams shall be done. It recommends requiring
previous experience of the material and of the designer and
installer in similar applications. It suggests that the owner
develops the design or at least the guidelines for the design,
to assure that the outcome of the waterproofing project is in
line with the expectations and respectful of the criteria of
safety, durability, capital investment and cost of mainte-
nance. Providing a detailed design and fixed requirements,
the owner holds responsibility of the design, but has full
control of it. Providing only guidelines, the owner transfers
responsibility of design on the tenderer, but the design is
not under his control and there is no certainty that it will be
approved by the authorities.
Appendixes
Appendix 1 consists of the database of dams on which
geomembrane systems have been implemented. The con-
tent of this database is not in the Bulletin due to the size of
the data. The version submitted to ICOLD was ‘‘frozen’’ at
31 December 2006 and lists 264 dams; from the trans-
mission to ICOLD, the number of dams with geomem-
branes has kept expanding, and the latest updating of
September 2014 listed 316 dams. This relates exclusively
to dams for which technical forms are available, but there
are many other dams that to the knowledge of the authors
incorporate a geomembrane.
Appendix 2 contains a list of terms and technical defi-
nitions concerning geomembranes, as produced by IGS, the
International Geosynthetics Society.
Appendix 3 contains the main references of the testing
standards on the use of geomembranes and implementation
of various dams.
Conclusions
Geomembrane systems have reached a high degree of
sophistication and reliability, and are recognised as a long-
term waterproofing method, when adequately designed and
installed. The satisfaction on the technical and economic
efficiency of the installed systems, as expressed by the
owners, is very high.
The height of lined dams has dramatically increased
over the years. Successful dam projects using geomem-
branes show that there is no theoretical limit for any type of
dam: at present, geomembranes have been installed on
embankment dams up to 198 m high (Karahnjukar, Iceland
2005), on gravity dams up to 174 m high (Alpe Gera, Italy
1993/1994), on new RCC dams up to 188 m high (Miel 1,
Colombia 2002), on tailings dams up to 230 m (when
completed, Las Bambas, Peru, ongoing). Performance after
decades of service shows that the very low permeability of
geomembranes is maintained over time, and that
geomembranes left exposed on the upstream face are able
to resist very aggressive environments (UV rays, ice,
waves, impact of debris, etc.).
In 2016 it is estimated that there are at least 400 large
dams in the world lined with geomembranes, mainly made
of PVC and mainly exposed. Underwater installation of
geomembranes in dams has become a kind of routine, and
has opened the way to systems that allow installation in
hydraulic tunnels with up to 900 m of head, and under-
water placement in canals without stopping the water flow.
The new Water Saving Basins of the Panama Canal
Expansion (2016) have been lined with an exposed PVC
geocomposite with an expected durability exceeding
100 years.
Acknowledgements Bulletin 135 was prepared by the European
Working Group, consisting of the following members: E. Aguiar
Gonzalez (Balsas de Tenerife, Spain), P. Bartek (Swiss National
Committee), M. Blanco Fernandez (Laboratorio Central De Estruc-
turas Y Materials C.D.E.X., Spain), P. Brezina (Povodi Odry, Czech
Republic), H. Brunold (Austrian National Committee), D. Cazzuffi
(ENEL CESI, Italy), H. Girard (Cemagref, France), M. Lefranc
(French National Committee), J. L. Machado do Vale (Portuguese
National Committee), C. Massaro (Azienda Energetica Metropolitana
Torino), J. Millmore (British National Committee), L. Schewe
(German National Committee), A. Scuero (Italian National Com-
mittee), P. Sembenelli (Italian National Committee), G. Vaschetti
(Italian National Committee), with the assistance of R. M. Koerner
(Drexel University/GSI, USA).
References
1. CIGB–ICOLD (1981) Use of thin geomembranes on fill dams.
Bulletin 38
2. CIGB–ICOLD (1991) Watertight geomembranes for dams. Bul-
letin 78
3. CIGB–ICOLD (2010) Geomembrane sealing systems for dams—
design principles and review of experience. Bulletin 135
4. Kline RA et al. (2002) Design of roller-compacted concrete
features for Olivenhain dam. Dams, innovations for sustainable
water resources. In: Proceedings, 22nd USSD conference, S.
Diego, USA
5. Liberal O et al. (2003) Ageing process and rehabilitation of
Pracana dam. In: Proceedings, ICOLD 21st International Congress,
Montreal, Canada
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