Water Power and Dam Construction - Issue September 2009

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REHABILITATION

WWW.WATERPOWERMAGAZINE.COM SEPTEMBER 2009 21

assistance to the government in the elaboration of energy policies

that promote development and investment in hydro power.

HE UNKNOWN

In 2005, USAID made a commitment to the Government of Georgia

to assist in the rehabilitation of numerous mothballed or degraded

small hydro power plants. Most of the candidate sites were origi-

nally built in the 1950s and 1960s a nd m any had not been func-

tioning for years. Because USAID aims to su pport sustainable

economic development based on market principles, the programme

focused on small hydro plants that were privately owned and whose

rehabilitation could be commercially viable. To maximise resources,

USAID limited its direct contribution to no more than 25% of the

total project rehabilitation cost, and in most cases its financial con-

tribution was much less than that. The balance of the investment

funding needed to come from owners’ equity and/or loans.

REP started by identifying and screening potential projects. After

technical and fin ancial evaluati on, several sites were selected for

detailed feasibility study and design. These projects were fully pri-

vatised and commercially viable, were under committed ownership

with sufficient equity, and were located in rural communities with

a need for more relia ble electricity supply to stimulate economic

development and job creation.

Two projects were initiated but were not completed. One project

was terminated after financing had been approved because of the

owner’s non-performance under his grant agreement. The other pro-

ject withdrew after selection due to a change in ownership structure.

REP provided technical assistance to the project owners on pro-

ject design and the development of business plans. Then REP worked

on identifying and securing financing opportunities for the projects.

The owners also needed assurance that they would be able to sell

their power to the grid at fair and commercial rates, so REP worked

with the government to ensure that appropriate power purchase

agreements and tariffs would be in place. To accomplish this, leg-

islative an d regulatory changes needed to be made by the

Government of Georgia, key among them market rules allowing the

HE country of Georgia has significant hydro power poten-

tial but many of its small hydro plants had been decom-

missioned or neglected in the later years of the Soviet

Union. Although these were either operating well below

design capacity or not operating at all, many were considered to be

good candidates for rehabilitation and in some cases expansion. The

US Agency for International Development (USAID), which has been

providing energy assistance to Georgia for over a decade, saw an

opportunity to change this by demonstrating the commercial via-

bility of such projects. This proved to be a great challenge in a post-

Soviet country where project finance was an unknown mechanism,

independent power generation was a new concept, and banks did

not understand project risks or how to mitigate them.

USAID’s answer has been the Rural Energy Programme (REP), a

US$11.5M p rogramme implemented by Winrock Internat ional

under a cooperative agreement, designed to increase energy supply

in rural areas, strengthen private interest in renewable energy devel-

opment, and strengthen the ability of Georgian agencies and com-

panies to promote clean energy development. This has been one of

the principal energy activities supported under the US Government’s

assistance programme in Georgia.

The programme is focused on areas that offer the greatest poten-

tial to meet local energy demands:

• Increasing the supply of grid-connected and off-grid renewable

energy in rural areas.

• Improving management of local renewable energy production.

• Building in-country capacity in rural energy and renewable energy

applications.

• Promoting sustainable natural resource management.

• Creating a favourable policy environment for rehabilitation, devel-

opment, and financing of small hydro power plants.

Increased hydroelectric generation capacity is seen as a key factor in

Georgia’s energy security, given the location of key generation plants

in conflict zones, and partial reliance on power imports from Russia.

The USAID-sup ported programme was also designed to provide

Many of Georgia’s small hydro plants are not working and in need of rehabilitation.

Winrock International was given the task of demonstrating the bankability of such

projects. This proved to be a great challenge in a country where project finance was an

unknown mechanism, and banks do not understand project risks or how to mitigate them

Big boost for Georgia’s small hydro

Official opening of the 2.5MW Kakhareti project

22 SEPTEMBER 2009 INTERNATIONAL WATER POWER & DAM CONSTRUCTION

REHABILITATION

system operator to purchase all small hydro generated energy at a

short-term average cost. The success of the programme depended

on this change as without it there were not sufficient guaranteed rev-

enues for projects to be commercially viable.

In 2006, Georgia’s energy sector was in a state of flux. The gov-

ernment had passed an amendment to the Law on Electricity and

Natural Gas, deregulating all small hydro power plants (<10MW).

This meant that there was no guaranteed offtake by licensed energy

sector participants, and that small hydro would be permitted to sell

to anyone, including licensed sector companies and private electric-

ity users at freely negotiated prices. Unfortunately, with few poten-

tial industr ial customers and issues of their cred itworthiness as

customers, the only viable customers would be electrical distribu-

ion companies and the independent market operator.

In addition to deregulation, Energo-Pro, Georgia’s largest electri-

cal distribution company, was also in the process of being privatised.

The privatisation included six hydro power plants providing Energo-

Pro with a dominant market position in distribution and generation.

The d eregulation of small hydro power pl ants wa s intend e d to

open the market for these producers, but instead constricted it to the

point of impracticality by forcing the producers to compete with

existing hydro plants with low tariffs.

A number of donor organizations, including USAID, helped con-

vince the government that if it was serious about achieving energy

security and reducing dependence on imported electricity and natur-

al gas, it would have to find a way to make small hydro viable.

During the summer of 2007, meetings were held between the

Ministry of Energy, energy sector regulators, and energy sector com-

panies, with REP representing the interests of small hydro opera-

tors. These m eetings reformulated the relat ionships between all

sector participants. The outcome was that new market rules includ-

ed provisions for the independent market operator, ESCO, to pur-

chase all unso ld small hydro output at a rate representing the

weighted average of the month’s balancing electricity purchases. This

would then provide rehabilitated small hydro guaranteed revenue

to repay their loans.

Financing for these projects can be broken down into two phases.

In Phase 1, USAID would provide limited fin ancial assistance to

complete fi n an c in g needs. In addition, REP expanded training to

owners and potential investors in Georgia’s energy sector in an effort

to create market conditions under which projects would be possible

without grant assistance (Phase 2).

Phase 1 included the creation of a loan facility supported by the

European Bank for Reconstruction and D evelopment (EBRD),

which made the full loan amounts available to Georgian banks for

on-lending. The ideal financing equation was to be 40% owner’s

equity, 40% commercial loans, and 20% USAID grants. It was

agreed that any losses would be equally sh ared by EBRD and its

Georgian partner.

The Bank of Georgia was the first bank to consider financing for

small hydro projects. While there were delays as the two institutions

worked out differences in evaluation criteria and approval sched-

ules, the Lapota a nd Okami projects eventua lly were financ ed

through this agreement. The success of these two projects raised the

confidence of the Bank of Georgia, and the interest of other banks.

The project next approached banks who expressed an interest in

making energy related loans. Georgia’s TBC Bank financed the next

two projects – Misaktsieli and Machakhela.

In 2008, USAID announced that there would be no more grant

money available for small hy dro pro jects. It was time for REP to

attempt to finance Sulori throug h pure equity and debt proj ect

financing. In the end, Cartu Bank, which was also working with

EBRD loans, was compelled by the project’s financial potential and

provided a loan to the owners of the Sulori plant which succeeded

in meeting the objective of pure project finance.

USAID believes that this phased approach was one of the keys to

the success of the programme. It also believes this model would be

applicable for financing energy and other infrastructure projects in

developing countrie s whe re investor confidence level s need to be

raised substantially to attract investors to the market.

EMONSTRATING PROJECT FINANCE

While the scene has been set to develop the remaining 4-7000MW

of untapped hydro generation in a country rich with hydro

resources, REP is no longer accepting new projects. The project was

never intended to assist with the rehabilitation of all non-working

small hydro in Georgia, only to demonstrate that it would be possi-

ble to actually enable rehabilitation based on project finance. That

was proven with the completion of the Sulori small hydro plant.

Under the auspices of the REP, local business consultants have

been trained in how to prepare business plans and funding propos-

als to assist future developers. Bankers, other financial institutions

and inves t o r s have been trained in the art of understandi n g what

nergy projects are, how to assess risks and when to make loans.

Unfortunately, due to the disruption to the Georgian economy in

the aftermath of the August 2008 conflict, political instability within

the country and the global economic crisis, few new rehabilitations

have been initiated at this time.

There is some interest in investing in Georgian hydro generation

by foreign investors who would rely on energy exports for a signif-

icant portion of their revenues. The export m arket is currently

restrained by transmission capacity to Turkey. With this in mind,

Georgia is working on a new 500kV transmission line that is expect-

ed to come on line in 2013.

Nikolas Okreshidze, Senior Energy Engineer,

USAID/Georgia, nokreshidze@usaid.gov

Horst U Meinecke, Chief of Party, Rural Energy Program,

Georgia, Winrock International, hmeinecke@winrock.ge

The US Agency for International Development is the

principal foreign assistance mechanism of the US

Government, working in 85 countries worldwide on

projects ranging from economic growth and energy

development, to education and health improvement, and

the strengthening of democratic governance systems

(www.USAID.gov).

Winrock International, the implementer of the Rural

Energy Program under a USAID Cooperative Agreement

is an independent, nonprofit organisation that works with

people in the US and around the world to increase

economic opportunity, sustain natural resources, and

protect the environment (www.winrock.org)

& D

Georgia’s REP small hydro projects

The projects fall into three different categories:

Rehabilitation of small hydro plants with partial US Government funding

(Five Projects): Kabali (1.5MW), Kakhareti (2.8MW), Lapota (2MW),

Misaktsieli (2.6MW), and Okami (1.6MW)). These projects were financed with

owners’ equity, USAID grants and commercial debt. These projects are

complete and in commercial operation.

Rehabilitation of small hydro facility with no US Government funding (Two

Projects): Algeti (0.25MW) and Sulori (0.8MW)). These project were financed

with owners’ equity and commercial debt. Both projects are complete and in

commercial operation.

Installation of micro hydro power plants (Three projects): Gadamshi micro

hydro, a 40kW, off-grid installation supplying a small village in Western

Georgia which had been without electricity for 15 years. Shenako (50kW)

and Kekhmor (80kW) in the high mountainous region of Tusheti are also off-

grid installations which supply nine high altitude villages which are now only

occupied during the summer months. These latter two projects are financed

by grants from USAID and the World Bank, and in-kind contributions from the

communities of labour, supplies and construction materials.

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the field poles were still originals from the early 1950s, it was decid-

ed that the field poles for both units should also be refurbished.

HALLENGES

Of particular interest in this rewind project is an innovative approach

in coil manufacturing and installation. Contractor National Electric

Coil (NEC) is preparing coils with flexible knuckles. Typical arma-

ture coils have hard insulation that is cured in the factory. Because

both Flatiron units 1 and 2 have a small core diameter, the typical

hard, fully cured coils could crack during the installation process. To

address this issue, NEC is employing the flexible knuckles which cure

after installation, allowing the coil to flex without cracking.

Another challenge to this rewind is the changing and competing

public demand associated with the project benefits of supplemental

water and power. Water scheduled for diversion and storage through

the project is based upon two primary factors: water user demand

and electrical demand on the western third of the US power grid.

When the C-BT first began delivering water and generating power

in the early 1950s, 85% of the water diverted and delivered was for

agricultural use. Over the last 60 years, end- use of the water has

changed. Today, more than 65% of the water diverted and delivered

goes to municipal and industrial use. Because water is moved

through the project to serve water customers on a schedule opti-

mised for power production, the change in end-use impacts the over-

all operations of the C-BT and how it generates hydro power.

Unlike the eastern part of the country where regular rain provides

for agricultural interests, the 17-western US served by Reclamation

are very arid, requiring irrigation augmentation. The agricultural

season in the West typically runs from late spring into mid-fall. It

begins with the snowmelt running off the mountains, down rivers

and streams, into the valleys and plains. Reservo irs capture that

water and store it for augmentation to irrigation through the rest of

the growing season, usually mid-to-late October.

When the use of C-BT water started moving from agriculture to

municipal and industrial supply, demand on the project ceased fol-

lowing a seasonal schedule. Instead of seeing an end to the water

HE 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).

Authorised in 1937, the C-BT was constructed from 1938-

1959. While individual parts of the project came on line at different

times, the majority of the project’s hydroelectric power generation

became operational between 1950 and 1954.

One of the more complicated projects const ructed by the US

Bureau of Reclamation (USBR), C-BT spans over 884km, diverting

water und er the US Continental Divide and dropping more than

884m in elevation. It serves nearly 800,000 people and 600,000 irri-

gated acres, generating approximately 759MkWh of electric ity a

year. The project has provided these benefits for over 50 year s of

operation in the face of changing and competing public demands.

UMPED STORAGE

Flatiron is a three-unit power plant located on the lower end of the

C-BT system of dams, reservoirs, tunnels, canals and power gener-

ation. Flatiron operates under an average net head of 322m, with

an original nameplate capacity of 71.5MW. The power plant con-

tains two main power-generating units and a reversible 13,000hp

pump-turbine unit which lifts water southward from Flatiron reser-

voir (afterbay) to Carter lake reservoir. This unit is capable of dis-

charging a maximum of 11m

/sec into Carter Lake by pumping up

through a 2.25km long connecting pressure tunnel.

The pumping lift through the Carter Lake pressure tunnel ranges

from 61-91m, depending on the water surface elevation at Carter

Lake. During peak load demands on the project system, water can

be released from Carter Lake back down to Flatiron reservoir

through unit 3. At such times, the pump-turbine operates in reverse

to generate 8.5MW of power.

In 1983, General Electric uprated Flatiron’s two main units from

35MW each to 43MW. Adding the 8.5MW capacity from unit 3,

Flatiron today has a total generating capacity of 94.5MWW.

This year, USBR is replacing the stator cores and armature wind-

ings in Flatiron’s main generating units 1 and 2, as well as refurbish-

ing the field poles. In 2006, unit 1 had a severe electrical short

damaging coils and core laminations, taking the unit out of service.

Work was performed to replace the damaged coils and repair the dam-

aged core laminations, and the unit was put back in service at full

capacity. Although the repair was successful, unit 1 later experienced

another electrical short in a different area of the winding. As a result,

it was determined that full replacement of the stator core and arma-

ture windings in unit 1 was needed. Through a value engineering study

and extensive testing, it was decided to perform the same work on

unit 2 because, like unit 1, the generator was nearing the end of its

life. To take full advantage of the rewind unit outages, and because

The US Bureau of Reclamation is

undertaking refurbishment work at the

Flatiron power plant in Colorado

Rewind at

Flatiron

The Flatiron power project. Photo courtesy

of the US Bureau of Reclamation

REHABILITATION

WWW.WATERPOWERMAGAZINE.COM SEPTEMBER 2009 25

year wrap up in October, demand for project water is now almost

year-round. This not only narrows the maintenance schedule across

the C-BT, but also puts additional wear and tear on all of the facil-

ities, including power plants.

For this reason, a specification section was included in the rewind

contract with NEC. It requires the contractor to verify that each gen-

erating unit can handle continuous operation at 16m

/sec at 322m

net head. The turbine on unit 1 had been replaced in the 1980s, and

the winding a few years later under separate contract. While both con-

tracts effectively uprated the unit, neither contractor provided docu-

mentation regarding the uprated capacity. This lack of documentation

constrained operation of the entire C-BT. If one of the two primary

units at Flatiron was out of commission, the project could not deliv-

er its full 16m

/sec capacity. By constraining water flow at the plant,

power production was also limited. Specifying the documentation will

eliminate these kinds of mechanical limitations on future operations.

Additionally, each unit at Flatiron will also undergo an indepen-

dent mechanical evaluation. Confirmation from the independent

evaluation will also help ensure that both units 1 and 2 can meet the

continuous 16m

/sec at 322m of net head demand.

The change from an agriculturally driven water year to a munic-

ipal-industrial driven water year also narrows the overall mainte-

nance schedule of the C-BT. With this in mind, the rewind contract

on b oth units was modified to fit a sc heduled outage d uring the

water diversion time of year.

This meant that new technology was used where possible to expe-

dite the repair process. To accommodate the accelerated work sched-

ule, NEC used a FARO laser tracker to align the stator bore with

the centre of the head cover.

Due to the expedited acquisition for the generator repairs, turbine

overhaul was not included in the scope of the work. Normally, with

the head cover off and the turbine out of the hole, a contractor

would drop a plumb line (tight wire) down the centreline of the unit.

The centre would be determined from the seal rings which are

embedded in concrete just above the draft tube liner. However, being

only partially unstacked made this more traditional approach inef-

fective and a laser tracker was used instead.

INDING AND STATOR

Two engineers completed the stator iron and winding design.

Unstacking the unit was performed by a subcontracted millwright

crew of four to five. The removal of the stator wi nding and iron

core was completed by a three to four man NEC crew.

While the old winding an d stator were being removed, NEC

stampe d and finished the new s tator core l aminations. This

involved about a half-dozen NEC employees working at a NEC

facility. Windings were also fabricated concurrently.

Once the old core was removed, NEC installed new bu ilding

bolts. The laser tracker was used to locate and verify that the build-

ing bolts were concentri c and plumb. This w ork was completed

using a four-man crew from NEC and a single person from the

alignment subcontractor.

NEC removed the pole keys (pairs of opposed steel wedges that

when driven against each other fix the rotor pole to the rotor

spider) in order for them to be shipped offsite for electrical i nsu-

lation replacement—previously they had contained asbestos.

As this article went to press, NEC is testing the n ew stator

iron. The next step will be to i nstall the n ew winding a nd, at the

same time, install the rebuilt rotor poles. USBR is taking the

opportun ity provided by the testing to correct some minor mis-

alignmen ts and restore the thrus t and guide be arings. This work

is being completed unde r a modification to the original contract

so that the overall project can be kept on schedule. The mechan-

ical evaluations are being completed by a one-person unit sub-

contra ctor.

Throughout the w ork, the Flatiron power plant has be en kept

operational by staging wor k so that water f low cou ld continue,

albei t not at the full capacity of 16m

/sec. Once all work at t he

plant is completed, these limitations will be overcome and the

power plant can move into the future better equipped to meet the

demands of a new century.

For more details visit www.usbr.gov

IWP& DC

26 SEPTEMBER 2009 INTERNATIONAL WATER POWER & DAM CONSTRUCTION

expansion. After the bushings were machined and the holes elon-

gated, the stator roundness immediately improved although there

was still some degree of ovalness.

The high vibrati on at the generator guide bearing app eared to

riginate from the rotor roundness and concentricity. Since the rotor

has a small concentricity, balancing the unit was recommended.

This case demonstrates the importance of undertaking compre-

hensive tests and analysis upon commissioning of a new or refur-

bished machine. Repeating the process in subsequent years and

comparing and trending parameter evolution, dynamic behaviour

and mechanical condition is valuable. For example, after the first set

of test results from RH Saunders dam, the machine was considered

reliable in the short term. However, it was only through further test-

ing at later dates that other problems were detected and rectified.

Such testin g can provide information whic h is invaluable for dis-

cussion with manufacturers, enforcing warranty terms and imple-

menting condition based inspections.

For more information visit www.vibrosystm.com

ROBLEMS and anomalies with new or refurbished machines

often develop unsuspectingly within the first years of opera-

tion while still under warranty. By detecting such phenome-

na at commissioning and throughout the warranty, it is

ossible to trend their evolution, initiate discussion with the manu-

facturer, and take immediate corrective actions to ensure long term

performance and reliability.

A good case study to illustrate this is the RH Saunders dam on the

St Lawrence River in Canada. Shortly after commissioning in 1995,

a series of test measurements were performed on a new hydrogen-

erator using the ZOOM system from VibroSystM.

The tests were to verify the integrity of the new machine’s tolerances

and dynamic behaviour and use these as a baseline for future reference.

At commissioning the unit maintained good mechanical stability

in all operating conditions. Static measurements matched the rec-

ommended erection tolerances but the rotor concentricity at full load

slightly exceeded erection tolerances. This caused a slight magnetic

shift which was also revealed by the vibration data at the generator

guide bearing.

As second series of test measurements taken two years l ater

pointed to:

• A significant deterioration of the stator roundness.

• A slight increase in the rotor roundness.

• Improvements in both rotor and stator concentricities.

• A high shaft vibration at the generator guide bearing.

The stator tendency to adopt an oval shape was considered to be

abnormal for a two-year unit and was most likely to be a design or

assembly problem with the radial key system. It was recommended,

while still under warranty, that discussions were initiated with the

generator manufacturer to study the problem.

It was also found that several stator hold-down bolts and upper

stator brackets had lost radial clearance and were hindering stator

REHABILITATION

ZOOM system

The ZOOM is a zero outage on-line measuring system, designed specifically

to monitor hydrogenerating machines thoroughly. Its capabilities include the

tool to trend parameters, diagnose anomalies, and prevent failures in order

to improve machine efficiency and reliability by reducing maintenance

activities, downtime and related costs, says VibrosystM.

ZOOM’s strength is its ability to synchronise the measurement of multiple

parameters and to correlate them to the minimum air gap of each rotor pole.

VibrosystM says it permits global and comprehensive analysis of machine

condition and behaviour. In addition to the air gap, users can integrate:

• Shaft displacement and vibration. • Magnetic flux.

• Stator displacement and vibration. • Turbine clearance.

• Stator winding vibration and temperature. • Stator core temperature.

• Rotor pole temperature. • Bearing temperature.

• MW, MVAR, voltage, and current. • Gate opening.

Its open architecture provides configuration flexibility to suit machine or

customer monitoring needs, from vital signs (8 to 16 parameters) to

extensive (24 to 64 parameters) monitoring, and integration of existing

instrumentation from any source. According to VibrosystM, this makes it a

very easy and affordable tool to implement.

Automatic and test measurements taken over one or multiple machine

rotations, as well as trends over days and weeks, can be visualised in

rectangular, polar, and spectral fashion through the ZOOM Software.

Vibration can be displayed in spectrum and orbit graphs, while stator

temperature can be mapped in 2D. ZOOM can be used for local (LAN,

standalone) and remote (WAN, internet) monitoring. It can be interfaced with

plant control and machine protection systems.

Zooming in on condition monitoring

VibrosystM explains how premature ageing of a hydro generator can be detected from the outset

500

490

480

470

460

450

440

430

420

410

400

Air gap (mils)

Geometry (mils)

500

490

480

470

460

450

440

430

420

Air gap (mils)

Geometry

410

400

(mils)

Stator roundness

Minimum gap

Maximum gap

Average gap

Rotor roundness

Rotor eccentricity

Stator eccentricity

’

Below: V iews of the elongated hole on the upper stator bracket and bushing

with zero clearance on the stator hold-down bolt

Below: Air gap behaviour and generator geometry at commissioning

IWP& DC

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28 SEPTEMBER 2009 INTERNATIONAL WATER POWER & DAM CONSTRUCTION

DESIGN

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time in the definition, acquisition and configuration of commodity

technology. Inbuilt flexibility of use enables immediate and essen-

tially infinite availability to grow capacity in response to demand.

No more the dilemma of whether to invest in additional capacity

before winning the design contract, or losing delivery time after the

win while procuring that capacity.

The dezineforce service gives subscribers access to a broad range

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OST ADVANTAGES

There are also significant cost benefits to a SaaS approach to engi-

neering design compared to conventional approaches. Recent

research (see www.catalyzt.com for more information) has com-

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Importantly, the analysis covered the complete cost of computer-

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It compared the costs over a three-year cycle and came to a defini-

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At higher volumes, it rises to a massive 70% saving through multi-

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This last factor includes minimisation of late-in-design-cycle changes,

dezineforce is a web-based engineering design search and optimisation service that is

available online through a flexible subscription package. Peter Collins explains how the

service can help compress design cycles and minimise costly design errors

Engineering the future – online

IWP& DC

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30 SEPTEMBER 2009 INTERNATIONAL WATER POWER & DAM CONSTRUCTION

TUNNELLING

La Confluencia is located on the Tinguiririca, Portillo and Azufre

rivers and consists of intakes and c onveyance systems on two

branches diverting flows to a surface powerhouse.

The Portillo branch compr ises a low weir and spillway on the

Portillo River at 1460m asl, with an 11km low-pressure tunnel that

runs to the surge chamber above the powerhouse, wh ile the

Tinguiririca branch has a 9.3km low-pressure tunnel.

Tunnelling forms the dominant part of the works, amounting to

41% of the direct civil costs.

UNNEL ADVANCE

The Andes are characterised by uplifted sedimentary, volcanogenic

and intrusive units of highly variable nature. As a result, it has not

been possible to predict the rock conditions that the contractor will

find as tunnelling progresses. However, fast progress is necessary

and as two tunnel faces are b eing worked upon s imultaneously,

together with ancillary underground works, clearing the spoil quick-

ly is vital to the progress of the project. The projected rate of tunnel

advance is around 9m per day to b e achieved in two cycles of

drilling, blasting, cleaning and reinforcing per 24-hour period.

The Haggloader 10HR-B model was chosen because of its abili-

ty to work in narrow spaces, being able to operate and manoeuvre

in tunnels of between 4.5 and 6.2m in width. The bulk of the tun-

nels at La Confluencia are approximately 7m in width.

Another reason for using this type of unit was that the 10HR-B

can load on a continuous basis. The back-hoe digging system loads

the spoil onto the conveyor, which then fills the haulage vehicle with

a constant flow. The conveyor can be raised and lowered to suit the

loading height of different haulage vehicles. Once the haulage vehi-

cle is full it is replaced with another and the 10HR-B therefore can

work on a continuous basis until the spoil is cleared. The loading

capacity is as high as 360m

per hour.

The construction period for La Confluencia is expected to be three

years, depending largely upon the rock conditions encountered by

the tunnellers.

The local GIA distributor, HRI Sa, is also currently negotiating

deliveries for other hydro-electric power projects in Chile.

www.gia.se

EVEN Gia Industri Haggloader 10HR-B underground back-

hoe loaders are being used by main contractor the Hochtief-

Tecsa Joint Venture for the excavation of tunnels on the La

Confluencia hydroelectric project built in the Chilean Andes.

The rubber-tyred loaders, manufactured in Sweden, ar e being

deployed to load spoil from the tunnel face via their backhoe and

conveyor system onto haulage trucks for removal out of the tunnel

and away from the site. This system means that the loaders can stay

in place continuously until the spoil is cleared and the tunnel is ready

for the next round of drilling and blasting.

ROJECT DETAILS

La Confluencia is being developed 150km south of Santiago by the

Tinguiririca Energia, an electricity operating company made up of

Australian utility Pacific Hydro and SN Power, a Norwegian ven-

ture of utility Statkraft and the Norfund Power Invest AS fund.

The Hochtief-Tec sa JV, formed between the German co mpany

Hochtief’s Chilean subsidiary and the Chilean Tecsa SA, started

work on their EUR 175M (US$253M) contract in January, work-

ing on a 70:30 basis to provide the engineering, procurement and

construction for the project.

Located in the Tinguiririca Valley in the foothills of the Andes, the

158MW La Confluencia is a run-of-river project involving the design

and construction of a powerhouse to install two turbines, approxi-

mately 20km of tunnel and two river diversions. Total cost of the

project is US$350M.

Clearing the load at La Confluencia

The project will feature around 20km of tunnels

The Hochtief-Tecsa Joint Venture is using seven Gia Industri Haggloader underground

loaders to clear excavated rock from more than 20km of tunnel during construction of the

La Confluencia hydroelectric project in Chile; with a further three units on order