BAUERon Large Dams

Passion for Progress... and Progress inWater ResourceDevelopmentBased on experience of more thanfifty years BAUER Spezial tiefbau GmbHas the parent company within theBAUER Group, evolved into one of the largest and most respectedspecialist foundation organizationswhich provides excellent service,equipment and innovation in ground engineering techniquesnecessary for Dam construction.The strength of our company are In-house resources facilitatingworld-class solutions to projectsaround the globe with the goal todeliver safely, on time, on budgetand with no surprise.

Contents

"Bauer on large Dams" – Worldwide

▪ Hinze Dam Upgrade, Australia▪ Merowe Dam, Su dan▪ Péribonka Hydroelectric Development, Canada▪ The "Naga Hammadi Barrage", Egypt

Bauer’s – Contributionto make your Water Resource Development feasible

▪ The Cut-Off Wall – The See page Barrier▪ Greenfield Projects – Design and Construction▪ Upgrade, Rehabilitation and Repair Projects

Bauer Quality and Safety Strategy

▪ Ground Pre-Treatment▪ The continuous Seepage Barrier

Bauer Equipment and Technique

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The Hinze Dam is located on theNerang River, 15 km southwest ofNerang in South East Queensland. Itprovides the major part of the watersupply for the Gold Coast region. Thefirst construction of the Hinze Dam

was made in 1975. The raise duringthe second stage was in 1985 up to alevel of 93.5 meters. During Stage 3the dam will be raised by 15 meters toapproximately 108 meters and willdouble up the water capacity.

The upgrade will provide an additional79,000 million litres of flood storagecapacity and increase the dam’s yield byat least an additional 16 million litres aday. The project will also provide greaterflood mitigation for properties down-stream of the dam and will make thestructure compliant with current damsafety design guidelines and standards.

Within the Hinze Dam upgrade designstage the permeability on the dam andthe foundation was evaluated. It wasfound that the increased water pressurehas an impact on the right abutment,due to the presence of highly permeablechert and greenstone, greywacke witha discrete series of defects as well ascontinuous defects in geological con-tact zones.

This unfavourable geological formationinfluences the seepage through thestructure, which causes increased leak-age through the foundation, internalerosion and piping.

The design team concluded that onlya plastic concrete wall which cuts offthe seepage through the hard rockstrata (UCS up to 150 MPa) will meetall the requirements providing a reliable,sustainable seepage barrier.

The Cut-Off wall of 220 m length, upto 50 m deep and 0.8 m thick con-structed by Bauer begins within theexisting saddle dam, extends throughthe section of the central core andkeys into a 5,000 m² hard bedrockarea below the core where seepagewill be decreased to its minimum.

▪ Cut-Off wall by Bauer Cutter andClamshell

WORLDWIDE

Hinze Dam Upgrade

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Cutter HTS 65

Cut-Off wall Panel

The Merowe Dam is designed to serveseveral purposes, namely: the genera-tion of electricity from its 1,250 MWhydropower station; the developmentof centralized agricultural irrigationschemes (about 300,000 ha) and theprotection of the Northern Stateagainst devastating high floods of theriver Nile. The Dam is located at thefourth cataract on the River Nile atMerowe. The project has a high priori-ty in the National ComprehensiveStrategy, because the country is suf-fering from an acute shortage of electricity power, which impedes theeconomical and social development.

The main dam of the Merowe project isa classic earth core rock fill dam (ECRD)with a central earth core, fine andcoarse filters and upstream and down -stream rock fill shoulders with a totallength of 883 m and a height of 64 m.

The ECRD is founded on alluvial sedi-ments, which are up of 30 m thick. To

control seepage below the dams' clay core, Bauer installed an approx.400 m long, 1.2 m thick plastic con-crete Cut-Off wall down to 64 m,which penetrates about 4 m into veryhard bed rock (up to 110 MPa UCS).On top of the Cut-Off wall a cushionof highly plastic material is providedto avoid stress concentrations in thewall and cracking of the core.

Dam internals e. g. spillway, stillingbasin and many other structures arebuilt with Bauer bored piles andsecant pile walls.

▪ Cut-Off wall by Bauer Cutter andClamshell

▪ Bored Pile and Secant Pile WallInstallation by Bauer BG DrillRigs

WORLDWIDE

Merowe Dam

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Cross View Cut-Off Wall

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Cutter CBC 135

The Péribonka dam is located in theheart of the province of Québec,Canada. The project involves the con-struction of a main earth dam acrossa main and secondary valley, two maindikes and a hydroelectric generatingRun-Of-River station with an estimatedcapacity of 385 megawatts.

Under the main dam body, the con-struction of an exceptionally deepCut-Off wall was required, to create aseepage barrier in highly permeableriverbed alluvia.

Bauer was awarded the contract onthe basis of an alternative design: theplastic concrete Cut-Off wall to becompletely embedded in the bedrock,a design which avoided any potential-ly hazardous area to be sealed bycement grouting.

The Cut-Off wall was exceptional by its depth, reaching almost 116 m, and being surrounded by complexgeotech nical ground conditions.

Bauer commissioned a hydraulic cut-ter, the CBS CBC 135, the biggestever manufactured, which includednew features and was designedspecifi cally for the construction of thePéribonka dam Cut-Off wall. Besidethe extreme depth of the bed rock, thedesign was further complicated by thepresence of hard rock including gran-ite, with strength sometimes in excessof 200 MPa, quasi vertical rock cliffs,rock overhangs, and gullies filled withcoarse alluvia, including boulders.

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Péribonka HydroelectricDevelopment

approx. 50 m0

10 m

20 m

30 m40 m

50 m60 m70 m80 m

90 m

100 m110 m

120 m

bouldersup to 4 m

medium size boulders

alluvium

Glacial Gully

Drilling and Grouting Works

In addition to the Cut-Off wall con-struction Bauer provided a completeconstruction package comprising soilimprovement of alluvium and man-made fill material by vibro densificationdown to depths of 48 m – rock consoli -dation and contact grouting as well as

construction of a grout curtain to depthsof up to 150 m by drilling and grouting;and the installation of permanent andtemporary dewatering systems.

With the plastic Cut-Off wall construct -ed in Péribonka, the technique has

Cut-off Wall fully embedded in rock

Cut-off Wall combined-with Cement Grouting

Deep Vibrator

proven to provide solutions for damsin ground conditions which are beyondthe limits of other techniques such ascement grouted cut-offs.

▪ Earthworks▪ Water Well Installation by

Bauer BG Drill Rigs▪ Drilling and Grouting with Bauer

small diameter drill rigs and Bauerbatching and pumping plants

▪ Soilimprovement with Bauer Vibroflotation System

▪ Cut-Off wall by Bauer Cutter and Clamshell

WORLDWIDE

Original proposal Bauer's proposal

The old Naga Hammadi Barrage, oneof three structures constructed between1900 and 1930 along the River Nile inUpper Egypt, is located 130 km northof the city of Luxor and 360 km down-stream of the Aswan Dam. The reser-voir feeds an agricultural irrigationsystem of 320,000 ha year-round.

A conceptual study comparing rehabili-tation of the existing barrage versusthe construction of a new barrage con-cluded that a new 330 m long seven-gate dam, raising the water level up to8 m, for irrigation should be built alongwith a ship lock and a 64 MW Run-Of-River hydropower plant. This was con-sidered the most economic alternativefor which geologically favourable con-ditions were identified 3 km down-stream of the existing barrage.

The study of the alternatives involveda variety of complex and technically

challenging tasks, including 3-D mathe-matical modelling of groundwaterflows, physical hydraulic model tests,

optimisation calculations, comparisonof flood protection concepts and a comprehensive environmental impactassessment for the project.

To facilitate the construction of the mul-tipurpose barrage, Bauer installed theseepage barrier consisting of a plasticconcrete Cut-Off wall with a depthdown to 60 m. The wall toe is embed-ded into a silt/clay layer and providesan excellent impervious cut-off, whichenabled the excavation of the largetemporary construction pit down to30 m below river level. Bauer installedseveral water wells for the dewateringof the construction pit. The Cut-Off wallis approx. 1,800 m long and occupiesan area of approx. 243,000 m².

▪ Cut-Off wall by Bauer Cutter andClamshell

▪ Water Well Installation by BauerBG Drill Rigs

WORLDWIDE

Naga Hammadi Barrage

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Well installation

1 : 15

1 : 2.5

Project Lay-out

Construction Stage 1

Construction Stage 2

Turbines

Weir

Locks

Cut-Off wall

Cut-Off wall installationWell installation

DewateringExcavationBuildings

Bauer Cut-Off Walls provide new oppor -tunities for investors and designersinvolved in Water Resource Develop -ment projects. When planning a newWater Resource Development project,one of the major obstacles is finding alocation with suitable geological andhydrological formations for the project,which also has appropriate environ-mental and social aspects. Bauer Cut-Off Walls can be installed in anytype of ground condition to provide areliable, durable and impermeable(approx. 1x10-8 m/sec.) system whichensures efficiency, durability, stabilityand safety for your project. Thus, theBauer Cut-Off Wall makes selection ofthe project site one step easier.

Bauer Cut-Off Walls convert the exist-ing ground conditions to meet yourdesign requirements, at a location of

your choice. The ability to install thewalls in remote areas, enables you tomeet environmental and social require-ments of dams.

As part of Dam Safety Program, Damowners, municipal, state and privateconduct regular reviews of all theirdams. Although the condition of a Damhas not changed since it was built,reviews of the purpose or the designidentify a need for upgrades to increasecapacity or to enhance life span anddam safety which maybe compromiseddue to hydraulic conditions or duringmajor earthquake.

Other existing barrier systems, forexample those constructed with con-ventional grouting methods, often failto meet the degree of efficiency anddurability and other performance speci-fications over the life of the structureas required by the design.

BAUER’S CONTRIBUTION

Cut-Off Wall –The Seepage Barrier

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temporary diversion

Greenfield projects – Design and Construction

Upgrade, Rehabilitation and Repair Projects

Design and Construction Stage 1

Design and Construction Stage 2

Upgrade Stage 1

Upgrade Stage 2

Rehabilitation Stage 1

Rehabilitation Stage 2

national standards all plastic and/orstructural concrete mixes are devel-oped and approved in our labs andare designed by our experts.

By using our professional employeeson all our projects, Bauer guaranteesthe quality of the Bauer Cut-Off wallto meet the required specifications.

Pre-Treatment

The continuous Cut-Off wall

Treatment by deep soil mixing

Firm ground conditions are necessaryin order to ensure reliable Cut-Off wallconstruction. Loose or soft soil layers in the dam embankment or at the foun-dation level or cavities in the rock mayhave an impact on quality and safetyand therefore should be pre-treated by grouting, deep soil mixing or othersoil improvement techniques.

The goal is to create a uniform soil envi-ronment for a continuous, homogenousand safe Cut-Off wall embedment.

Based on extensive experience Bauer uses methods, equipment and techniques which allows safe construction of continuous, homogenous Cut-Off walls.

TECHNISCH KOMPETENZ

Bauer Quality and Safety Strategy

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PP

P

SS

Treatment by grouting

Cutter Flap Control

3-D-rendering of a Cut-Off wall

Operators Screen

Successful function of a Cut-Off walldepends on essential requirements:▪ embedment▪ continuity▪ homogeneity

Therefore, the Cut-Off wall is built with overlapping primary and second-ary panels using a special construc-tion process. The main steps in Cut-Off wall construction are deep panelexcavation followed by concreting.Deep excavations are done withBauer Cutters and/or Grabs – highquality maintained bentonite suspen-

sion provides efficient stability duringpanel excavation.

Special developed electronic systems(B-Tronic) used in all Bauer machinesallow the verification of the correctinstallation of each panel. In additionto other parameters, actual deviationand depth are shown online on acomputer screen enabling the opera-tor to control the excavation process.All parameters are recorded continu-ously for QA/QC purposes (B-Report).Additionally gathered data, using In-house 3-D-rendering tools produce adiagram showing the wall continuity.

To verify panel information an ultrasonic measuring system is also used.

After the excavation process is finishedthe bentonite suspension is displacedby concrete. In accordance with inter-

Pre-Treatment Zone Pre-Treatment Zone

1.4.

2. 5.3.

Cutting and desanding process

Cutter wheels for all geological conditions

TECHNISCH KOMPETENZ

Bauer Equipment and Technique

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Cut-Off Wall Construction Technique

Primary Panel cutting

Using the latest equipment in cut-ting and desanding technology,Bauer constructs Cut-Off walls alsoin difficult geological conditions.

Primary Panel concreting Secondary Panel cutting and concreting

for normal soil for medium hard rock for hard rock

Pump

Cutter

Mud pump

MixerDesander

6“ pipes

BAUER Spezialtiefbau GmbHBAUER-Straße 186529 Schrobenhausen, GermanyTelephone: +49 8252 97-0Telefax: +49 8252 97-1496BST@bauer.dewww.bauer.de

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Richard Boudreau, Principal Director –Production Projects, Hydro-Québec Equipment

and SEBJ, about Péribonka Project

"It means a lot to me to say thank you to theteams of Hydro-Québec, SNC Lavalin and Bauer.

Because of the fusion of their energy, know-how and skills the works were completed

in excellent quality within the given time frame. After completion of this successful phase

now, we can begin with the construction of the dam so that the filling of the basin can be

started as planned in autumn 2007.Congratulations!"

Dam ProjectsWorldwide