Water Power and Dam Construction. Issue June 2010

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essential.

Made to measure reliable

solutions for your hydro power

applications.

www.marellimotori.com. Innovation and technology since 1891.

22 JUNE 2010 INTERNATIONAL WATER POWER & DAM CONSTRUCTION

NORTH AMERICA

Managing and maintaining the condition of

critical structures and assets for function-

ality, lifespan assessment, and regulatory

compliance are common challenges for dam

owners. Hibbard Inshore helps its custom-

ers address these challenges by giving them

quantiable data on the underwater por-

tions of their structures allowing them to

plan and perform necessary maintenance

proactively.

Structures Hibbard Inshore can inspect

include: trash racks, lower outlets, dam

faces, intakes, head gates and seals, sto-

plogs, reservoir bathymetry, toe of dam,

penstocks (ooded and dry), turbines, tur-

bine shut off valves, diversion tunnels, and

long conveyance tunnels.

Hibbard offers a wide variety of vehicles

and sensors to t any level and physical

length of project, and can attach a wide

variety of hydraulic and electric tooling to

unmanned vehicles.

In January 2010 the company used

unmanned techniques to dredge 76m3 of

debris in the forebay and intake areas of an

existing plant while adjacent units were oper-

ating. This project removed the sediment to

allow proper operation of the customer’s unit

while limiting the impact on plant operations

and maintaining the highest safety standards

for the project. Hibbard Inshore has also

just signed a new sonar and video inspection

contract for a previously uninspected 7.3km

power tunnel in Central Asia.

www.hibbardinshore.com

Available from Ludeca, the Inclineo is

a powerful measurement system utilis-

ing high precision electronic inclinometer

technology with a resolution of 0.0003

degrees. In combination with interchange-

able mounting bases Inclineo measures rel-

ative or absolute angularity, atness, level

or parallel surfaces; as well as plumbness of

vertical shafts, perpendicularity of planes,

and straightness along a line. Its rotatable

housing allows the Inclineo to take meas-

urements at any angular position, including

surfaces with a steep inclination. The three-

key operation makes Inclineo versatile and

simple to use, says the company.

Shaft plumbness is calculated by com-

paring the Inclineo measurements at

opposite positions. The tool attaches to

the shaft magnetically. The value for the

plumbness of a vertical shaft is obtained

by comparing measurements 180 degrees

apart. Measurements are then taken at the

45 degree positions to conrm measured

results. Finally, on shafts consisting of sev-

eral sections, measurements are repeated

at each of them, verifying the position of

the entire shaft relative to the plumb line.

Ensuring that the shafts are plumb reduc-

es wear, imbalances, vibrations, higher

temperatures, increases bearing life and

improves overall efciency.

www.ludeca.com

LUDECA Booth 117

IBBARD INSHORE Booth 964

Top: Crawler Moving into penstock for dry

inspection; Bottom: Navajo with additional

lighting for dam penstock inspection

Mead & Hunt is providing the full range

of engineering consulting services to utilities

and private investors for the development of

ten active US hydroelectric projects totalling

over 136MW. Many of these projects are

located at existing non-hydro federal navi-

gation, ood control and irrigation projects

where close coordination with the US Army

Corps of Engineers and the Department of

Interior Bureau of Reclamation is essential.

Hydro is being installed at existing non-

hydro state-regulated dams and new units

are being added at existing FERC-regulated

hydroelectric projects to increase capacity.

For these current projects, Mead & Hunt

is completing feasibility assessments, hydro

design, plans and specications, and is pro-

viding on-site construction supervision.

Mead & Hunt’s water resources core

competencies have always been FERC

licence application and regulatory com-

pliance assistance. They assist hydro

owners with innovative and cost-saving

solutions to resolve dam safety issues.

Financial assessment services are provid-

ed to clients to investigate the availabil-

ity of federal and state stimulus funding.

Mead & Hunt also performs due dili-

gence services for equity investors seek-

ing hydro opportunities and preparation

of preliminary permit applications.

Mead & Hunt is an architecture and

engineering firm located in 14 offices

nationwide. Company founder Professor

Daniel Mead was an internationally rec-

ognised pioneer in hydrology and hydro-

electric engineering, and contributed to

establishing ethical standards and con-

tracting guidelines for the industry.

www.meadhunt.com

MEAD & HUNT Booth 545

Mahoning Dam in Pennsylvania

24 JUNE 2010 INTERNATIONAL WATER POWER & DAM CONSTRUCTION

NORTH AMERICA

Paul C. Rizzo Associates (Rizzo) was

founded in 1984 on a strong background

in civil, structural and geotechnical engi-

neering, and its engineers have always had

a particular dedication to dams and water

resources projects. It has worked with

regulatory agencies and environmental

groups in both public and private sectors

around the world on projects such as small

spillway design and construction, large

dam rehabilitations, complete rebuilds and

hydroelectric development.

Rizzo recently served as construction man-

ager and engineer of record for the Taum

Sauk upper reservoir rebuild in Missouri,

US. The dam rebuild required the place-

ment of 2Mm

of RCC and 229,000m

conventional concrete, making it the largest

RCC dam in North America.

The construction of the rebuilt dam

required the cooperation of the owner

(AmerenUE), the contractor (Ozark), the

engineer (Rizzo) and state and local regu-

latory agencies to overcome challenges at

the site. These included:

r4VCTVSGBDFDPOEJUJPOTUIFGPVOEBUJPO

rock contained clay seams and zones

which required special excavation and

fracture foundation treatment.

r3FNPUFMPDBUJPOPGUIFGBDJMJUZBTUIFEBN

was constructed on top of a mountain, the

transportation of equipment, materials

and labour was a continuous challenge.

r/VNFSPVT DPODVSSFOU DPOTUSVDUJPO

activities –required to meet the aggressive

construction schedule. These included

excavation, foundation preparation and

RCC placement and occurred on a daily

basis, requiring an enormous construc-

tion management effort.

The benefits resulting from the suc-

cessful rebuild of the Taum Sauk Upper

Reservoir are tremendous and will only

increase when it becomes fully operation-

al. The most important benet is the long-

term safety of the people living near the

reservoir and those visiting the surround-

ing recreational areas.

The Taum Sauk rebuild was recently

awarded the prestigious US Society on

Dams 2010 Award of Excellence.

www.rizzoassoc.com

PAUL C. RIZZO ASSOCIATES Booth 625

PCX Corporation specialises in the

design, manufacture and delivery of off-

site prefabricated electrical and mechani-

cal solutions that reduce construction

time, minimise environmental impact,

reduce installation footprints, and the

reliance on local site labour.

Typical PCX offsite solutions include

packaged electrical power systems, modular

distribution systems, skid based mechani-

cal packages, and custom operator control

stations. It is no secret that collapsing the

construction schedule allows for acceler-

ated start up of the hydro facility and the

construction industry is looking for ways to

change the project delivery model. Utilising

3D Building Information Modelling (BIM),

constructors are discovering that modular

and offsite construction techniques can be

implemented as never before. Accurate

integrated designs are readily available

with just in time delivery to your site.

Factory tested and commissioned systems,

manufactured concurrent to the site con-

struction, allow for earlier generator start-

up. No more waiting for critical equipment

to arrive and be manually installed in the

eld. Other positive advantages are noise

reduction and an improved safety record.

www.pcxcorp.com

PCX CORPORATION Booth 107

38KV gas insulated substation power

equipment centre

The unique demands of the hydro market

call for technology that is not always

available off the shelf. VibroSystM con-

tinually endeavours to meet this demand.

Alongside its FOA-100 that measures

end-winding vibration and the VM6.0

that dynamically measures air-gap,

VibroSystM furnishes many unique

designs that meet the changing needs of

the high-tech sector.

VibroSystM ThermaWatch Rotor probe

and signal conditioner provide a fast-re-

sponse, on-line temperature reading from

salient and non-salient eld poles on large

rotating machines. Its 4-20mA output can

be connected to VibroSystM ZOOM on-

line monitoring system or to any other

instrumentation. Because of its small size

(5.9mm probe tip), the ThermaWatch

Rotor is easy to install through a stator

core ventilation hole or at any other loca-

tion where the sensor tip can be positioned

in front of a rotor pole, rotor pole circuit,

joint or rotor pole bar. ThermaWatch

Rotor is a solution for monitoring rotor

pole face and winding temperature with-

out affecting rotor integrity.

Plug-ins, such as ZOOM Orbits, Polar

Plots and FFTs are developed to take full

advantage of the sensors to which they

are connected. Its software environment

allows the user to make efcacious and

complex analyses. The ZOOM 6 Platform

is based on over 20 years of machine mon-

itoring experience. It is an open architec-

ture software for on-line monitoring of

large rotating machines. This platform

also allows notication, alarm, and condi-

tional measurement and alarms (single or

multiple conditions).

The ZPU-5000 (ZOOM processing

unit) simultaneously monitors multiple

parameters on large rotating machines. It

performs various types of measurements

in automatic and test modes, processes

data, checks alarm conditions and trans-

mits data to the ZOOM controller for a

quick and efcient data interpretation of

machine condition through the ZOOM

6 platform The ZPU-5000 can synchro-

nise acquisition of all parameters with the

passing of each rotor pole for salient pole

machines, or use an external acquisition

trigger for non-salient pole machines.

www.vibrosystm.com

VIBROSYSTM Booth 567

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Please visit us at:

PANOLIN AG CH-8322 Madetswil/Switzerland +41 44 956 65 65 www.panolin.com

26 JUNE 2010 INTERNATIONAL WATER POWER & DAM CONSTRUCTION

NORTH AMERICA

PUMP-TURBINE REFURBISHMENT

AT BLENHEIM-GILBOA

ew York Power Authority’s (NYPA) Blenheim-Gilboa

pumped storage power project was returned to service

in November 2009 as part of a major overhaul that

continues to progress. Work on the nal phase of a

US$135M life extension and modernisation (LEM) programme is

scheduled for completion in June 2010.

The Blenheim-Gilboa pumped storage project is located in the

Catskill Mountains in New York State, US. The 1040MW project is

owned and operated by NYPA and first produced commercial power

in 1973. It consists of an underground powerhouse with four Hitachi

260MW pump/turbine units, with one common penstock from the

upper reservoir feeding four spherical valves. The gross head range

on the units is 324.9-348.4m.

In 2003 NYPA began the process of upgrading and modernising

the project’s four reliable but ageing pump-turbine units, with engi-

neering and model testing of a new pump-turbine design. The rst

phase of construction began in September 2006 with the shutdown of

the rst unit and replacement of the pump/turbines and many major

mechanical and electrical components. Since then, the process has

been repeated three times, in the autumn of 2007, 2008 and 2009,

with the third unit being successfully upgraded and brought on line

in May 2009.

Three of the four pump-turbine generating units were also returned

to service in November 2009 following the project’s shutdown in

mid-September to permit replacement of a spherical valve on the nal

pump-turbine generating unit to be refurbished.

The project work scope includes the following major tasks:

r Refurbish the four pump-turbines, including replacement of the

turbine runner with improved efciency, increased capacity and

reduced potential for cavitation of the turbine runner. The tur-

bines will be upgraded so that each generator/motor will operate

at up to approximately 318MVA at 0.9 power factor, or 286MW

as a generator, and up to approximately 420,000HP, or 318MW

at 1.0 pf motoring, at a temperature rise of 80°C.

r Replace one and refurbish three spherical valves.

r Dewater the upper reservoir to facilitate spherical valve

replacement.

r Replace 17kV G/M air blast circuit breakers with new SF6 circuit-

breakers.

r Replace the rotating, shaft mounted exciter with new static excita-

tion systems.

r Replace starting motor (SM) liquid rheostat (LR) controls and

instrumentation with a PLC-based system and switchgear to allow

the use of any rheostat to start any of the four units.

r Replace/refurbish internal components of the liquid rheostat

electrolyte tank.

r Refurbish the motor/generator including a thorough cleaning,

re-insulating the eld poles, re-rounding the stator and air cooler

replacement.

r Installation of a new condition monitoring system for machine

diagnostics.

r Replace the iso-phase heat exchangers/coolers.

r Replace the mechanical Woodward governor with a new elec-

tronic governor.

r Refurbish the G/M phase reversal switch.

r Replace the 285MVA generator step up transformers with

325MVA new 17KV/345kV, 325MVA transformers.

r Furnish and install a new transformer deluge system.

r Installation of new redundant generator protection relays.

The three units successfully completed to date have demonstrated sig-

nicant improvements in pump and turbine efciency, greater stable

operating range, increased pump ows and increased maximum tur-

bine output.

At the conclusion of the LEM programme it is projected that

Blenheim-Gilboa will be capable of producing approximately

1160MW from the same amount of water.

Focus on refurbishment

Over the past few years there have been some impressive refurbishment projects undertaken

in the hydro power and dams industry. Here, IWP&DC presents details on 10 of the most

interesting and innovative projects underway or recently completed in North America

Blenheim-Gilboa pumped storage project

Taum Sauk: view of the RCC wall

WWW.WATERPOWERMAGAZINE.COM JUNE 2010 27

NORTH AMERICA

LIFE EXTENSION FOR ST. LAWRENCE-

RANKLIN D. ROOSEVELT

The New York Power Authority (NYPA) continues to forge ahead

on its life extension and modernisation (LEM) programme at the St.

Lawrence-Franklin D. Roosevelt power project. In February 2010

NYPA had completed work on the 12th of 16 turbine-generators

to undergo refurbishing as part of the US$281M initiative in New

York state.

Refurbishment of the 13th turbine, which began immediately after

completion of the 12th, is expected to be completed by August 2010.

The programme is scheduled to run through to 2013.

The power authority began the St. Lawrence LEM programme in

1998 to replace or renovate the original major generating equipment

in the power project, and improve the overall performance exibility

and efciency of the facility which has operated continuously since

1958. The rst new turbine was delivered in May 2001 for an in-

service date of April 2002.

The work has required a highly coordinated effort involving nine

major component manufacturers in achieving numerous installation

milestones. Among the most signicant activities has been the disas-

sembly and removal of the turbines, the major component of the

turbine-generator units, and the renovation of their turbine-pit loca-

tions to facilitate the installation of the refurbished units.

Alstom Hydro USA was awarded two independent contracts in

1998 and 2004 to manufacture all 16 replacement turbines. The tur-

bines are of two different designs, corresponding with the original

equipment manufactured by Baldwin Lima Hamilton (BLH) and Allis

Chalmers (AC).

At the time of St. Lawrence-FDR’s construction more than 50 years

ago, no single manufacturer could meet the ambitious schedule for

supplying the turbines. The responsibility was evenly divided between

BLH and AC. Since 2007, the LEM programme has centred on the

AC turbines, following the replacement of the eight BLH units.

Among the design advances in the replacement turbines is a more

efcient shape for harnessing available water from the St. Lawrence

River to generate power. The new turbines also use stainless steel

instead of the carbon steel composite of the original equipment.

Stainless steel is more resistant to corrosion and requires less main-

tenance, which will contribute to extending the life of the hydro-

electric project.

Other elements of the LEM have included generator rewinding,

installation of new switchgear, replacement transformers, and mod-

ernisation of protection and control systems.

The main features of the St Lawrence-FDR power project include

the Robert Moses-Robert H Saunders dam, which stretches 975m

across the St Lawrence River. The dam includes 32 turbine-gen-

erator sets with 16 operated by NYPA and 16 by Ontario Power

Generation, producing 800MW for each utility. Over the decades of

its operation, the St. Lawrence-FDR project has produced more than

340B kWh of electricity, which would be sufcient power to meet

electricity demand in the US for one month.

REBUILDING TAUM SAUK

Extensive refurbishment has taken place at the 408MW Taum Sauk

pumped storage project in eastern Missouri. The plant started gen-

erating electricity again four and a half years after the collapse of

the project’s upper reservoir dike in December 2005. The Federal

Energy Regulatory Commission (FERC) authorised project owner

AmerenUE to resume normal project operations at the project after

completion of the rebuilding work in April 2010.

Paul C Rizzo Associates was hired by the dam’s owner AmerenUE

to investigate the cause of the dam collapse, as part of a FERC

requirement. Following substantial investigation and design, Rizzo

concluded that substandard construction and instrumentation prob-

lems were partly responsible for the breach, earmarking the following

points as key causes: stability failure; poor design; specication and

maintenance of instrumentation and control systems.

It was determined by Rizzo that a repair of the existing dike was

not technically feasible due to aws in the original construction.

Substantial areas of the existing dike were founded on residual

soil. Additionally, few construction controls were utilised to con-

trol the gradation and character of the rockll. Due to this and a

number of other factors, a complete re-build of the upper reservoir

was required.

The original construction of the upper reservoir was accomplished

by attening the top of Proft Mountain, using rhyolite and exca-

vated residual soil to construct the existing concrete face rockll

dike. After the breach, it was discovered that signicant quantities

of residual nes were mixed with the rock, and the rock itself had a

wide range of particle sizes, ranging from gravel sizes to as large as

1.2-1.5m in diameter.

The new dam is founded on fractured rhyolite with deep weather-

ing features, intrusive granites and weathered diorite dikes. A sym-

metrical RCC section will provide adequate factors of safety to meet

FERC stability criteria considering the subscribed foundation condi-

tions of the rock.

The new RCC dam is constructed along the same alignment as

the original concrete faced rockll dam. Since the upper reservoir

is founded on top of Taum Sauk mountain, it has no watershed.

The probable maximum ood (PMF) for the new RCC dam con-

sists of the rainfall within the reservoir. Therefore, the hydrology and

hydraulic criteria are limited to two major factors: the elevation of

the crest of the new RCC dam, including freeboard; the capacity of

the proposed overow release structure (spillway).

The overall design basis was to rebuild the upper reservoir so it will

have the same generating capacity as the original upper reservoir with

a normal pool and overall gross head, as established in the FERC

licence for the Taum Sauk plant.

The rebuilt reservoir project is currently the largest RCC dam in

North America, and was recently named the recipient of the Award

of Excellence in the Constructed Project during the US Society on

Dams 2010 annual meeting and conference.

NIAGARA POWER TUNNEL

Ontario Power Generation’s Niagara tunnel project includes the

planning, design and construction of a 10.2km long, 12.7m inter-

nal diameter tunnel to divert an additional 500m

/sec of water from

the Niagara river to existing generating stations. The project will

restore Ontario’s capability to effectively utilise the water allocated

to Canada under a 1950 river water diversion treaty signed between

Niagara project – intake channel excavation within the cofferdam

28 JUNE 2010 INTERNATIONAL WATER POWER & DAM CONSTRUCTION

NORTH AMERICA

Canada and the US.

When the new Niagara tunnel is in operation, the water it delivers

will permit the existing Sir Adam Beck generating station to produce

14% more energy. This will increase average annual output by about

1600GWh, enough to supply 160,000 Ontario homes with hydro

power.

The design/build contractor, Strabag, is using the world’s largest

hardrock tunnel boring machine (manufactured by The Robbins

Company) to excavate the tunnel. Work got underway in September

2006 and by 4 August 2009 excavation had ofcially reached the

halfway milestone.

However, in September 2009 planned maintenance work for tun-

nelling equipment was brought forward while a small rockfall was

investigated and repaired. The incident, more than 3km along the

tunnel well behind the TBM, happened in a stretch of tunnel that had

previously suffered overbreak problems. Both rock and the lining fell

in the accident but no-one was injured.

As of May 2010 the TBM had progressed to 6882m. The project

was scheduled for completion in mid 2010 but due to the poor

ground and tunnelling difculties, this has been re-negotiated to the

end of 2013.

EFFICIE NCY IMPROVEMENTS AT HOOVER DAM

The Lower Colorado river basin has experienced the worst drought

on record since the early 1900s. The 2074MW Hoover dam on

the Colorado river between Arizona and Nevada, has continued to

provide consistent water deliveries to Colorado river water users

throughout this time. However as a result of this, lake elevation at

Lake Mead behind Hoover dam is only at 44% of capacity, causing

concern about loss of total generation capacity (at 76% -1688MW);

loss of regulation capacity; increased rough zones; and increased

maintenance (cavitation) concerns.

Efciency and capacity improvements have been taking place at

Hoover dam since 1998. The work has involved:

r Major overhauls of turbine components.

r Stainless steel wicket gates.

r Opening existing wicket gates beyond 100%.

r Unit controls modernisation.

r Wide head range turbine.

Work on the wide head range turbine got underway in April 2010,

when Commissioner Michael L. Connor from the US Bureau of

Reclamation (USBR) announced the award of a US$3.4M contract

to Andritz Hydro Corporation of North Carolina. This was for the

design and manufacture of a new wide head turbine runner for gener-

ating unit N-8 in the Nevada wing of the Hoover dam power plant.

“The new turbines will allow the generating units to operate more

efciently over a wider range of head than the existing turbines do,”

Connor said. “That will enable Hoover dam to generate power more

efciently as the water level behind the dam uctuates between low

and high elevations.”

The new runner is scheduled to be delivered to the dam in February

2012 for installation by USBR. If it performs as anticipated, USBR

may exercise a contract option for additional runners for generat-

ing units N-6, A-1 (in the Arizona wing of the power plant), and

N-5. The total investment in the new turbines will be approximately

US$11.56M, and the additional runners would arrive at the dam in

November 2013, 2014 and 2015, respectively.

There are 17 commercial units in the Hoover dam power plant -

nine in the Arizona wing and eight in the Nevada wing. The existing

turbines are designed, in general, to operate over a higher range of

lake levels. At very low lake levels, operation of existing turbines

becomes rough and inefcient.

BE AR CR EEK REMEDIATION

The Tennessee Valley Authority (TVA) constructed the Bear

Creek Dam in 1969 to provide ood control, recreation, water

supply, and economic development benets. The dam is located

in Franklin County, Alabama, and is one of two dams in the Bear

Creek Project. The structure consists of an earth dam, a concrete

overow spillway with a highway bridge carrying County Road

37 across the spillway and dam, an intake tower, lined tunnel,

and an outlet structure. The dam is approximately 1200ft (366m)

long at the crest and is 68ft (21m) high at the maximum section.

The crest of the overow spillway is at elevation 602 and the crest

elevation of the dam is 618.

The dam is a homogeneous rolled ll embankment constructed

from compacted residual soil. It is founded on karst rock consist-

ing of the Mississippian age Bangor Limestone underlain by the

Pennington Shale and Bangor Limestone. During construction,

the existing overburden on the right abutment was excavated to

competent rock and approximately 900 feet of the foundation was

grouted using both vertical and angled grout holes. The existing

overburden was left in place along the remaining portion of the

dam to the spillway on the left abutment.

Seepage was observed at the downstream toe of the dam after

rst lling the reservoir in 1969. A grouting program was suc-

cessfully performed in 1972 to reduce the seepage ow in the area

from the right abutment to near the spillway. However, by 2004,

the seepage had again increased to about 800 gallons per minute

and TVA initiated another grouting program on the left side. Two

partial grout lines were installed before the work was halted due

to ooding.

Hoover dam on the Colorado River Bear Creek: Upstream face of the new RCC Dam used 79,000cy of RCC

WWW.WATERPOWERMAGAZINE.COM JUNE 2010 29

NORTH AMERICA

In addition, TVA has revised the PMF and determined that the

earth dam would be overtopped by this ood.

TVA requested proposals on methods of providing a cutoff for

the seepage and providing seismic stability and PMF capacity for the

embankment dam as part of the NEPA process. In response to this

proposal, Paul C. Rizzo Associates proposed constructing a deep seep-

age cutoff wall using either the secant pile or plastic concrete slurry

wall technique and alternative modications to the existing dam to

provide a dam capable of existing seismic and PMF demands.

Rizzo’s scope of work included the following major tasks:

r Phase I Conceptual Design and Design Report;

r Phase I Site Investigations; Field boring investigations, Surface and

down hole geophysical investigations, pumping wells and piezom-

eters to study ground water regime.

r Design of Cutoff Wall and Water Barrier;

r Geotechnical analyses and Report;

r Seismic evaluation of Intake Tower;

r PMF Development;

rFinal Design, Construction Drawings and Technical Specications;

r Request For Proposal Assistance to TVA

r Construction Oversight.

Treatment of the foundation under the varying and challenging con-

ditions emphasised a progressive design and construction of the nal

composite seepage barrier, wherein continuous, ‘real time’ evalua-

tion of the geologic conditions encountered during each phase of the

foundation treatment process were employed to adjust the scope and

design of the next step of the rehabilitation.

The end result is an RCC foundation and composite seepage bar-

rier that employed excavation, cleaning, and backll of near surface

karst features; installation of a double line grout curtain; and instal-

lation of discreet zones of concrete cutoff walls where geologic condi-

tions rendered grouting ineffective.

The project was completed in June 2009.

ADDITIONAL CAPACITY AT REVELSTOKE, CANADA

British Columbia isn’t producing sufcient electricity to meet increas-

ing demand, particularly during peak demand periods. Increasing the

capacity of existing hydroelectric facilities is one way BC Hydro is

helping meet this demand.

In anticipation of increased demand, BC Hydro is adding a fth

unit to the Revelstoke Dam and Generating Station. Revelstoke Unit

5 is the most cost-effective source available to BC Hydro for this addi-

tional capacity. It will add approximately 500MW of capacity, bring-

ing the facility’s total generating installed capacity to 2480MW.

The target in-service date for the Revelstoke Unit 5 project is

October 2010, with an allowance for an in-service date one year later

(October 2011).

As the Revelstoke Generating Station was originally designed to

house six generating units, the project will not involve signicant

changes to the facility. Construction includes:

r Installation of a fth penstock,

r Placement of concrete to form the draft tube and house the generat-

ing unit,

r Design, fabrication and installation of the generating unit,

r Electrical work to tie the generating unit into switchgear,

r Upgrades to existing generating station equipment

In March this year, three large generator transformers were success-

fully delivered to the station, the last of last of several oversized deliv-

eries for the project this year that also included transport of the thrust

bracket and turbine shaft

Now that all of the main components have been delivered, project

contractors will complete the assembly of the generating unit, trans-

formers and other electrical equipment. Once the assembly is com-

plete, BC Hydro will start a test phase of the generating unit and

related equipment.

The three transformers, each weighing 108 tonnes, were manufac-

tured in Varrenes, Quebec and transported by train to Revelstoke. A

143ft suspension trailer was used to transport the transformers down

Westside Road to the Revelstoke Generating Station. Once in place,

the transformers will transfer the additional energy supplied by the

fth generating unit currently being installed.

PEACE CANYON REFURBISHMENT, CANADA

In September 2009, BC Hydro successfully completed a three-year

C$120M refurbishment project at the 700MW Peace Canyon gener-

ating station in the Canadian province of British Columbia.

The project, which began in May 2006, was completed on time and

came in at approximately C$6M under budget. Work at the station

included replacing the stators, upgrading the rotors, and overhauling

the turbines of the plant’s four units.

Peace Canyon is the fourth largest hydro generating station in the

province and is a critical component of the BC Hydro system, provid-

ing an average annual clean energy generation of 3111GWh.

Construction of the 50m high Peace Canyon Dam began in

July 1974, and the rst unit came into service in April 1980.

The dam creates the Dinosaur Reservoir on the Peace River

approximately 23km downstream from BC Hydro’s GM Shrum

Generation Station.

View of Revelstoke Dam – a ﬁfth unit is being added to the project

Peace Canyon Dam – refurbishment work was completed in September 2009

30 JUNE 2010 INTERNATIONAL WATER POWER & DAM CONSTRUCTION

NORTH AMERICA

COATING WORK AT FLATIRON

The Flatiron power plant in the US state of Colorado is part of an

historic water diversion, storage, and hydroelectric system called the

Colorado-Big Thompson project (C-BT).

The feasibility study for the plant was carried out in 1937 and it rst

went into operation in 1954. In total, the Colorado-Big Thompson

Project consists of over 100 structures that together form a water

diversion system that spreads over 250 miles.

The Flatiron plant generates electricity for the project and provides

water to Carter Lake for delivery to other customers.

Flatiron uses a conventional pump generator and a Francis Turbine

to obtain its total generating capacity of 94,500kW – increased from

the original capacity of 71,000kW. The plant contains two main

power units and a reversible 13,000 horsepower pump turbine unit.

The power plant discharges its water into the Flatiron reservoir,

which is regulated to provide controlled water release into the foot-

hills storage and distribution system.

Flatiron uses a reversible pump to lift water from the Flatiron

Reservoir – the maximum lift needed being 297 feet. Water is then

taken through the Carter Lake 1.4 mile pressure conduit and tunnel.

When this action is reversed, the mechanical structure (Unit 3) acts as

a turbine-generator and produces electricity. This happens in periods

of high demand where water is released from Carter Lake to ow

back to Flatiron reservoir and 8,500kW of electricity is generated.

Unit 3 is capable of discharging a maximum of 370 cubic feet per

second into Carter Lake and operates on surplus or off-peak power

generated by the project’s other power units.

Water discharged from the power plant is then kept in Flatiron

Dam, which is used for afterbay storage. Gravity then takes it

north through the Charles Hansen Feed Canal, across the Big

Thompson River.

As part of the American Recovery and Reinvestment Act intro-

duced by President Barack Obama during the nancial crisis, the

Colorado-Big Thompson Project was awarded $14m and work will

now begin upgrading Flatiron by the US Department of the Interior

Bureau of Reclamation.

In April it was announced that USBR awarded a US$12.2M con-

tract to Abhe & Svoboda for recoating of the Flatiron penstocks. The

protective coating currently on the penstocks is over 50 years old and

in need of replacement.

Under the contract all previous lead-based paint and packing that

may contain asbestos will be removed and new packing added where

necessary. In addition, workers will install ultrasonic ow meters to

improve water accounting and power plant efciency.

Last year, USBR also began work replacing the stator cores and

armature windings in Flatiron’s main generating units 1 and 2, as

well as refurbishing the eld poles. Details on the rewind project,

carried out by National Electric Coil, can be found at http://

www.waterpowermagazine.com/story.asp?storyCode=2054093

or in the September 2009 issue of International Water Power &

Dam Construction.

WOLF CREEK DAM, US

Wolf Creek Dam is located on the Cumberland river in Kentucky,

US. It is operated and maintained by the Nashville District of the US

Army Corps of Engineers, providing ood control, power, recrea-

tion, water supply and water quality benets for the Cumberland

River system. Lake Cumberland, impounded by the dam, is the ninth

largest reservoir in the US and the Corps’ largest reservoir east of the

Mississippi river.

In 1968, muddy ows in the tailrace and two sinkholes near the

downstream toe of the embankment signaled serious reservoir seep-

age problems. Investigations indicated the problems were due to the

karst geology of the site characterized by an extensive interconnected

network of solution channels in the limestone foundation. Piping

of lling materials in these features and collapse of overburden and

embankment into the voids caused the problems. The District imme-

diately began an emergency investigation and grouting program

between 1968 and 1970 that is generally credited with saving the

dam. However, grouting was not a long-term x and a more perma-

nent solution was sought. After studying numerous alternatives, the

District chose to construct a concrete diaphragm wall through the

earth embankment into the rock foundation to block the seepage.

This wall was constructed between 1975 and 1979.

Since completion of the wall in 1979, District personnel have con-

tinued to closely monitor the project. While the original wall inter-

rupted the progression of erosion, seepage has since found new paths

under and around the wall and perhaps through defects in the wall

itself as erosion of solution features continues.

To address the seepage problems, the District prepared a Major

Rehabilitation Report, which recommended a new concrete dia-

phragm wall be constructed using newer technology that will reinforce

the purpose of the original wall. This new wall will start immediately

upstream of the right concrete monoliths and run the length of the

embankment, into the right abutment, for about 1280m. It will be

constructed to a depth which is deeper than the deepest sections of

the original wall, and as much as 23m deeper than the majority of

the original wall.

The rst phase began in September 2006 and was completed by

August 2008. It involved the installation of a double line grout cur-

tain on each side of the alignment of the new barrier wall. This phase

sealed openings in the rock to both improve the short term reliability

of the foundation, and reduce barrier wall construction problems due

to slurry loss. It also provided foundation information used in setting

the nal wall limits.

In December 2007, during the execution of this foundation grout-

ing, the District issued the solicitation for phase II of the founda-

tion remediation for the wall. The District awarded the barrier wall

contract to Treviicos-Soletanche JV, a Treviicos led joint venture

between Treviicos South, (the North America subsidiary of Trevi

headquartered in Italy) and Soletanche Construction (a subsidiary of

Soletanche-Bachy of France). The contract amount was US$341.4M

over a four-year period.

The notice to proceed for the 48-month contract was given to

the JV in October 2008. The installation of the protective concrete

embankment wall started in April 2009 and construction of the bar-

rier began in July 2009.

In March, the district announced partial suspension of work on

the project after instrumentation used to monitor the foundation

indicated movement and increased hydrostatic pressure since work

began in the area adjacent to the concrete section of the dam, which

includes Critical Area 1. The suspension affects only 600 feet of the

4400-foot long, 275-foot deep concrete barrier wall, and is expected

to last to 25 June. Meanwhile work is continuing in the non-critical

areas of the dam.

A detailed article on construction of the concrete cut-off wall

at the project can be found at: http://www.waterpowermagazine.

com/story.asp?storyCode=2053336 or in the June 2009 edition of

International Water Power & Dam Construction. Regular updates

on the project can also be found on http://www.lrn.usace.army.

mil/WolfCreek/index.htm.

Wolf Creek Dam

IWP& DC