Water Power Magazine

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LY 2010

JULY 2010

Serving the hydro industry for over 60 years

Tackling sediment at dams

Small hydro renaissance

Tackling sediment at dams

Pushing aheadProgress reports on hydro tunnel projects

I N T E R N A T I O N A L

& DAM CONSTRUCTIONWWW.WATERPOWERMAGAZINE.COM

JULY 2010& DAM CONSTRUCTIONWWW.WATERPOWERMAGAZINE.COM

Water Power

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& DAM CONSTRUCTIONWater PowerWWW.WATERPOWERMAGAZINE.COM

CONTENTS

Editor Carrieann Stocks Tel: +44 20 8269 7777 [email protected]

Contributing Editors Patrick Reynolds Suzanne Pritchard

Editorial Assistants Elaine Sneath, Tracey Honney

Advertising Sales Scott Galvin Tel: +44 20 8269 7820 [email protected]

Deo Dipchan Tel: +44 20 8269 7825 [email protected]

Tim Price Tel: +44 20 8269 7822 [email protected]

Classified Advertising Diane Stanbury Tel: +44 20 8269 7854 [email protected]

Senior Graphic Designer Natalie Kyne

Production Controller Lyn Shaw

Publishing Director Jon MortonOfficesUnited Kingdom: Global Trade Media, Progressive House, 2 Maidstone Road, Foots Cray, Sidcup, Kent DA14 5HZ, UK. Tel: +44 20 8269 7700, Fax: +44 20 8269 7804, Email: [email protected]: Ediconsult Internazionale, Piazza Fontane Marose 3, 16123 GENOVA, Italy Tel: +39 010 583 684, Fax: +39 010 566 578Japan: Masayuki Harihara, Yukari Media Inc., 3-4 Uchihiranomachi, 3 Chome chuo-ku, Osaka 540-0037, Japan. Tel: +81 6 4790 2222, Fax: +81 6 4793 0800. Email: [email protected]

Subscription OfficeFor subscription enquiries, single copies or back issues:Global Trade Media, PO Box 99, Sidcup DA15 OEN, UKTel: +44 845 155 1845, Fax: +44 20 8269 7877 Email: [email protected]

North America onlyInternational Water Power & Dam Construction (ISSN 0306-400X) is published monthly by Global Trade Media, Progressive House, 2 Maidstone Road, Foots Cray, Sidcup DA14 5HZ, UK. Periodicals postage paid at Rahway, NJ. Postmaster: send address corrections to International Water Power & Dam Construction c/o BTB Mailflight Ltd, 365 Blair Rd, Avenel, NJ 07001. US agent: BTB Mailflight Ltd, 365 Blair Rd, Avenel, NJ 07001.

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The paper used in this magazine is obtained from manufacturers who operate within internationally recognised standards. The paper is made from Elementary Chlorine Free (ECF) pulp, which is sourced from sustainable, properly managed forestation.

olume Number JULY 2010 3

DAMENGINEERING

ModernPowerSystemsCOMMUNICATING POWER TECHNOLOGY WORLDWIDE

COVER: Launching the invert concrete work platform at Niagara power tunnel project in December 2008. For a detailed report on progress at the project, see p20

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46 PROFESSIONAL DIRECTORY 48 WORLD MARKETPLACE

R E G U L A R S 4 WORLD NEWS 8 DIARY

F E A T U R E S

INSIGHT 10 Constructive consultation Why is construction consulting needed in hydro projects?

SMALL HYDRO 12 Small hydro renaissance Private hydro developers share their experiences

16 Bringing water power to the poor Micro hydro transforms lives in developing countries

18 Energy recovery from public water systems Making use of existing infrastructure

TUNNELLING 20 Niagara progress How is the Niagara power tunnel project progressing?

22 Glendoe bypass Details on the bypass to recover Glendoe’s headrace

24 Meeting challenges in Ethiopia Overcoming challenges at Beles II and Gilgel Gibe II

27 Excavation challenges and solutions at Jinping I Details on obstacles encountered at the Chinese scheme

NEW TECHNOLOGY/GENERATORS 32 The generation game Atlas Copco’s developments in generation technology

34 Generating interest in EMMA Introducing the energy and micro generator manager

MODELLING 36 Assessing flood risks for Goring and Streatley hydro Flood risk modelling on the River Thames

SEDIMENTATION 38 Tackling a growing problem Addressing the issue of sedimentation

41 All systems go for Sedi-filter Details on a new dewatering systems for dams

COMMENT 43 Hydro project engineering costs What will be the cost of engineering services?

4 JULY 2010 INTERNATIONAL WATER POWER & DAM CONSTRUCTION

WORLD NEWS

THE NUMBER OF LICENCES issued fo r smal l hyd ro power schemes by the UK’s

Environment Agency has increased substantially in the last decade, the government agency has announced, with the number of new schemes in the country expected to treble by 2020.

At the Chartered Institution of Water and Environmental Management (CIWEM) National Hydropower con-ference held yesterday, EA chairman Lord Chris Smith said that 31 licenc-es for hydro schemes were issued last year, compared to only five in 2000. This year the agency has already granted licences for 31 new schemes, with a further 166 applica-tions under consideration.

Currently, there are approximately 400 hydro schemes in England and Wales, and Lord Smith explained

this number is expected to rise to 1200 by 2020.

In March this year, the EA released the Hydropower Opportunities and Environmental Sensitivities Map which identi!ed almost 26,000 new locations where small scale hydro power could be deployed in England and Wales. Together, these sites could generate enough electricity to power up to around 850,000 homes and produce 3% of the country’s 2020 renewable electricity needs. In reality, however, only some of these sites could be exploited due to envi-ronmental sensitivities, as well as practical constraints such as access to the electricity network.

The new maps help to identify areas where hydro power could make a positive contribution to the local environment, and sites where it is less appropriate.

The report found that a sensitively designed hydropower scheme that includes a !sh pass could improve the local environment as well as gen-erate electricity in over 4000 sites. These opportunities are particularly concentrated on rivers such as the Severn, Thames, Aire and Neath.

With the government soon to offer subsidies of up to 20p for every kilowatt hour of electricity pro-duced, a medium-sized scheme that typically generates enough electricity for about 32 homes, could receive around £25,000 a year. Average set up costs range from £100,000 to £150,000. But, the Environment Agency stressed, only schemes that were well designed and had no nega-tive impacts on the river wildlife or the local environment would get the go ahead.

“Some hydro power schemes have

the potential to deliver low carbon electricity and improve the local environment for wildlife, for exam-ple by improving !sh migration. But there will inevitably be some sites where the risk to the environment outweighs the bene!ts of power gen-eration,” said Tony Grayling, Head of Climate Change and Sustainable Development at the Environment Agency. “With Government’s new feed-in tariff for renewably generated electricity, hydropower could become an attractive income generator for hydro power developers, if environ-mental safeguards are met.

“The report recommends that fish-friendly design needs to be incorporated in all schemes, and that grants for !sh passes could help to unlock the potential of small scale hydro power in England and Wales.”

UK sees surge in hydro development

Studies shortlist new dam sites in New Zealand

SEVERAL SITES HAVE BEEN identi!ed as potential locations for water storage dams on the

Ruataniwha Plains in New Zealand following initial geological studies in the region.

A report on the geological stud-ies has assisted both Hawke’s Bay Regional Council and the Ruataniwha Water Storage Dam Leadership to assess the viability of several sites. During the prefeasibility process the Regional Council started with an ini-tial list of 30 potential sites. This was then worked through and narrowed down to 14 sites of which six were considered most likely.

These original 14 shortlisted sites have had on-ground, physical geologi-cal/seismic assessments over the last two months. Of these, !ve are now considered unsuitable because

of ground condition risks. Some of the remaining set of sites are looking very positive but further assessment work is still underway. Relevant landowners in these areas are being contacted by Hawke’s Bay Regional Council and informed as sites are removed off the list.

“This is a completely normal part of the process to assess potential dam sites. It’s a complex project and our feasibility study as much about exclud-ing sites that have risks as including sites needing further investigation,” said Bruce Corbett, Group Manager, Water Initiatives for Hawke’s Bay Regional Council.

The study report was presented to the Ruataniwha Water Storage Dam Leadership group chaired by Sam Robinson earlier this month. The group is working with Hawke’s Bay

Regional Council to step through the feasibility work for the proposed water storage dams.

The geological studies have shown that there is ample dam site capacity in the north of the Ruataniwha Plains area but in the south there is less avail-able storage capacity which reduces options, particularly in Takapau.

The Council will focus further assessments now on sites where geological fatal "aws are not appar-ent, and where sufficient and eco-nomically achievable storage can go ahead. Fortunately, there is very good geological data available for the area which identi!es a lot of the numerous fault lines and unsuitable soils.

Eight of the potential sites now being studied can provide 90-110Mm3 compared to the maxi-mum storage requirement of 90Mm3

to serve the entire area of 22,500 ha. Likely dam positions close to those originally identi!ed are also being looked at.

The new and repositioned sites will reduce pumping requirements as they are more gravity fed. Two sites also offer hydro power potential.

GNS seismic studies are currently underway to confirm the geological assessments. This will also provide dam design parameters which will influence construction costs and therefore further decisions.

Parallel to this, the Regional Council’s water project team will be working with the Ruataniwha Water Users Group, and will meet with cur-rent irrigators and major dryland farm-ers in the irrigation zones to gauge and prioritise demand for stored water.

SN Power and IFC in Vietnam power agreement

NORWEGIAN RENEWABLE energy firm SN Power and the International Finance

Corporation (IFC) have entered into a Joint Development Agreement (JDA) that will see them develop sustaina-ble hydro power projects in Vietnam.

This agreement will enable IFC, acting through IFC InfraVentures, an early stage project development fund, and SN Power to develop an invest-

ment strategy, policy, and guide-lines to address Vietnam’s growing demand for power. The partners will acquire operating assets and invest in green!eld projects to build up a port-folio of renewable energy investments in the country.

The project will be IFC’s first investment in Vietnam through IFC InfraVentures, and SN Power’s !rst partnership in Vietnam.

“This IFC partnership will allows us to find viable hydro power projects and subsequently develop and operate them in a sustainable manner. SN Power has followed the Vietnamese power market for several years. We believe we can strengthen Vietnam’s long-term renewable gen-erating capacity through our power market experience and technology transfer,” said Erik Knive, Executive

Vice President SN Power Southeast Asia.

SN Power and IFC have collabo-rated previously on several of SN Power’s global investments in wind and hydro power plants in Chile, India, and the Philippines. SN Power uses IFC’s social and environmental performance standards for conduct-ing due diligence of acquisition and green!eld power projects.

WWW.WATERPOWERMAGAZINE.COM JULY 2010 5

WORLD NEWS

Nicaragua to boost hydro

NICARAGUA’S MINISTRY OF Energy and Mines (MEM) has confirmed that hydro gen-

eration activities in the country will increase signi!cantly within the next four to !ve years with 18 hydroelectric projects in the study phase and six projects currently under construction.

Nicaragua has a hydroelectric potential of 3280MW, of which only 98MW is currently being utilized. This represents a huge potential for com-panies interested in developing hydro-electric projects in the country, in

addition to the opportunities in other types of renewable energy sources, said PRONicaragua, the Nicaraguan Investment Promotion Agency.

The Tumarin project on the Grande River in Matagalpa could be one of the most important projects in the last 50 years in Nicaragua, according to representatives of the National Assembly. It is estimated to produce 250MW, one third of the country’s current demand, and will save up to US$100M in fuel imports per year.

THE WORLD BANK HAS APPROVED $350M to finance a Dam Rehabilitation and Improvement

Project which aims to improve the safety and sustainable performance of over 220 selected dams in India, and has also approved a credit worth US$146M for the second phase of a project to rehabilitate and modernize the Jinnah Barrage in Pakistan, and to improve irrigation and water manage-ment in the country.

India is home to about 4700 com-pleted large dams – almost half of which are more than 25 years old – with another 400 under construc-tion. The total water storage capac-ity of these existing dams is about 283Bm3. They have played a key role in fostering rapid and sustained agricultural and rural growth and development – a key priority for the Government of India since independ-ence. Irrigated agriculture and hydro power development have been major pillars of the government’s strategy to ensure food and energy security.

“Rainfall, which occurs mainly in intense and unpredictable downpours within short monsoon seasons, is of high temporal and spatial variability and does not meet year-round irrigation and other water demands. Considering this, storage of water is essential for India. However, many large dams are in need of modern safety measures and monitoring instru-mentation,” said Joop Stoutjesdijk, Lead Irrigation Engineer and Project Team Leader. “The project will help rehabilitate and modernize over 220 large dams in the states of Kerala, Madhya Pradesh, Orissa, and Tamil Nadu.”

In addition, the Project also aims

to strengthen the institutional, legal and technical framework for dam safety assurance within the Government of India and in the par-ticipating states.

Meanwhile, the Punjab Barrages Improvement Phase II Project aims to strengthen and modernize Pakistan’s Jinnah Barrage and af!liated works to enable reliable and uninterrupted supply of water for over 2.1 million acres of farmland bene!tting about 600,000 farm families for irrigation and domestic water users; and to build the capacity of Punjab Irrigation and Power Department’s ( IPD) in water resource management and irri-gation system management.

“The development and manage-ment of water resources of the Indus Basin is a huge challenge, requiring very high levels of administrative engi-neering and scienti!c capability. While there has been progress, the current irrigation and drainage system suf-fers from deteriorating infrastructure and weak governance,” said Masood Ahmad, World Bank Lead Water Resources Specialist and Project Team Leader. “To reduce volatility to growth, Bank support will include rehabilitation of barrages and con-tinued capacity development at the regional and federal level for manag-ing water resources.”

The World Bank has a long his-tory of partnership and collaboration with Pakistan and has supported more than 48 operations in irrigation, drainage, water resources develop-ment and the power sector. Jinnah Barrage is one of the highest priority barrages in the Indus System as it provides a bridge over the Indus River to link the roads between the Khyber Pakhtoonkhwa and Punjab provinces.

World Bank OK’s loans to India, Pakistan

From the EditorDear readers,Big news from the US this month was that Senator Lisa Murkowski, Representative of Alaska, introduced two pieces of legislation aimed at increasing the produc-tion of hydroelectricity in the country. The Hydropower Improvement Act and the Hydropower Renewable Energy Development Act have been developed to boost federal support for hydropower projects.

In particular, the Hydropower Improvement Act, co-spon-sored by Sen. Patty Murray, D-WA; Sen. Maria Cantwell, D-WA; and Sen. Mike Crapo, R-Idaho, aims to increase the capacity of the nation’s hydropower sources by up to 75,000MW.

The legislation establishes a competitive grants program and directs the Department of Energy to produce and implement a plan for the research, development and dem-onstration of increased hydropower capacity. The bill also gives the Federal Energy Regulatory Commission (FERC) authority to streamline the permitting and review process for hydropower projects (a move I’m sure would be wel-comed by the great majority of readers in the US), and calls for studies on pumped-storage sites and the potential for development at Bureau of Reclamation facilities.

The Hydropower Renewable Energy Development Act classifies hydroelectric power generation as a “renewable” resource for federal program purposes. This bill provides parity treatment for hydro in the Production Tax Credit (PTC) and expands the types of hydro that can qualify for the PTC and Clean Renewable Energy Bonds (CREBS) program.

When introducing the bills, Murkowski said she hoped the Senate can finally recognize the important contribu-tion hydropower, as a truly renewable resource, can provide to the country’s clean energy goals . Hydropower is the largest source of renewable electricity in the US, providing 7% of the nation’s power. In Alaska, hydro sup-plies 24% of the state’s electricity needs, and there are more than 200 additional sites that look promising for further hydropower development.

News of the bills was welcomed by the National Hydropower Association, particularly the fact that the bill includes provisions to help make existing hydro resources more efficient, convert existing dams to energy-generating resources, and support small conduit technologies, as well as pumped-storage project development. “This approach

focuses on new technologies and new approaches, not necessarily new dams,” said NHA Executive Director Linda Church Ciocci, adding that the association stands ready to work with Congress, the White House, and other stake-holders to ensure that hydropower is supported in any energy and/or climate bill that moves forward.

There is little doubt this is a great step forward for hydro in the US, and is a great sign for the future. It would allow the country to expand its exisiting developments and ensure continued development of new technologies, as well as offering extensive employment opportunities. Best wishesCarrieann Stocks,Editor


WORLD NEWS

In briefMOZAMBIQUE IS TO focus on developing its immense hydro potential before looking at other energy sources, the coun-try’s energy minister said during a recent conference in Basel, Switzerland. According to reports from Reuters Africa, Salvador Namburete told the confer-ence audience that the country’s top priority in terms of energy is to devel-op some of its 12,000MW hydro potential, later focusing on natural gas, wind and solar power. Namburete was reported as saying the country had no immediate interest in nuclear power.

CHINA SOUTHERN Power Grid (CSPG) has signed agreements with the Laos government to develop the Nam Tha 1 hydro power project and build a national power grid in the country, Dow Jones Newswires has reported.Signing took place dur-ing a state visit to Laos by Chinese Vice President Xi Jinping earlier this month.

GLOBALDATA HAS announced the release the “Ukraine Small Hydro and Mini Hydro Power Market Analysis and Forecasts to 2015” report which analyses the growth and evolution of Ukraine’s small hydro power mar-ket up to 2009 and gives historical and forecast statistics for the period 2001-2015. This research also gives detailed analysis of the market structures of the technology and regula-tory policies that govern it. For further details, please visit: www.globaldata.com/reportstore

NYPA plans $460M upgrade for part of Niagara power project

THE NEW YORK POWER AUTHORITY (NYPA) is planning a major overhaul of the Niagara Power

Project’s Lewiston Pump Generating Plant (LPGP) to extend the life of the hydroelectric project’s auxiliary facility and enhance its performance.

The Power Authority Board of Trustees approved a $460M Life Extension and Modernization (LEM) Program for the LPGP facility, which operates during periods of peak power demand in supplementing the electricity output of the Robert Moses Niagara Power Plant, the Niagara Project’s main generating facility. The trustees also authorized initial capital expenditures of $131M for the upgrade and the award of a 10-year contract to Hitachi Power Systems America, which was the lowest-cost quali!ed bidder for replacing and mod-ifying major components of LPGP’s pump-turbine generators.

“The Niagara Power Project is a tremendous asset to Western New York in providing some of the lowest cost electricity in the country, with its power production supporting tens of thousands of jobs on the Niagara Frontier,” President and Chief Executive Officer Richard M. Kessel said, announcing the upgrade project. “The Power Authority places the highest priority on being a good steward of this facility to ensure it continues to bring the greatest value to the region’s economy and the state’s electric power system. The Life Extension and Modernization Program that we’re planning at the

Lewiston Pump Generating-Plant is in keeping with this imperative, which also served as the basis for the Power Authority’s completion only a few years ago of a similar program at the Niagara Project’s Robert Moses Niagara Power Plant.”

In 2006, NYPA completed a $24M maintenance program at LPGP in the same year that it !nished a $298M, 15-year program to upgrade the Robert Moses Niagara Power Plant, where the Power Authority replaced turbines and retro!tted other compo-nents of all 13 generating units. The LEM at the pump generating plant will be an undertaking of similar scope, for overhaul of the plant’s 12 pump turbine generator units, which date back to 1961, when the Niagara project was !rst placed into service. The work will include replacing the turbine runners, the rotating portion of the equipment. The runners, which typically weigh about 75 tons, trans-fer energy from the water "ow to the generators.

The upgrade will begin in late 2012 under a schedule providing for the overhaul of a turbine generator unit every eight to nine months, with the final unit completed in 2020. The phase-in schedule provides for 11 of the 12 LPGP units to be available for operation during the LEM so that NYPA can meet its commitments to its customers.

In addition to extending the life of the pump generating plant, the refurbishing will lead to greater ef!-ciencies, allowing the plant to gener-

ate additional power with the same amount of water.

LPGP is one of two major pumped storage facilities in New York State - the other being the Blenheim-Gilboa Pumped Storage Power Project, anoth-er NYPA facility. In May, the Authority completed a four-year overhaul of that facility, in the northern Catskills.

The selection of Hitachi Power Systems America for replacing parts of the pump-turbine generators and associated equipment stemmed from a Request for Proposals that NYPA issued last December for the new equipment and rehabilitation work. The company, which was one of six bidders submitting proposals in response to the RFP, was awarded a $174M contract for carrying out the overhaul during the 2012 to 2020 time frame, with the contract amount including allowances for future in"ation.

Hitachi was also the company that upgraded and rehabilitated the pump-turbine units at Blenheim-Gilboa.

Hitachi and other contractors are expected to utilize local union trades people, including machinists, electri-cians, mechanics and welders, in sup-port of the LPGP work, contributing to economic development in the region. The work will include the disassembly and reassembly of equipment.

NYPA is also currently conducting a LEM program at another hydroelectric project, the St. Lawrence-Franklin D. Roosevelt Power Project in Massena. That initiative is more than three-quarters complete and scheduled to be !nished by 2013.

Andritz resumes Ilisu supply contract

TECHNOLOGY GROUP ANDRITZ says that it is to resume its con-tract to supply equipment to the

Ilisu hydro power plant in Turkey after improvements were made to aspects of the project’s environmental and social measures.

The supply contracts awarded to Andritz as well as a number of other European !rms were suspended tem-porarily in late 2008 after the export credit agencies of Austria, Germany and Switzerland said that speci!ed standards relating to the project’s impact on the environment, cultural heritage and resettlement had not been ful!lled.

Andritz’s EUR340M contract

includes the supply of engineering services, six 200MW Francis tur-bines, six generators and additional equipment. The company is part of an international construction consortium led by Turkey’s Nurol Construction.

According to Andritz, its contract will no longer be supported by the Austrian export credit agency, Oesterreichische Kontrollbank AG (OeKB).

In 2009, OeKB and two other European banks withdrew their sup-port for Ilisu after a deadline that had been set for socio-economic and cultural improvements to the project was not met. The banks’ support was designed to cover the European-based suppliers for the project,

including Andritz, Alstom, Ed. Zublin AG, Colenco and Maggia.

Turkey, which sees the EUR1.2B project as a key element of its social and industrial development plans, vowed to continue with Ilisu without the banks’ support. According to a statement from Andritz, the Turkish government says that “it will abide unchanged by the planned accompa-nying measures relating to environ-mental protection and to social and cultural aspects”.

Ilisu is part of Turkey’s Southeastern Anatolia Project, which aims to build 22 dams and 19 power plants on the Tigris and Euphrates rivers and their tributaries.

Let IWP&DC’s readers know about your forthcoming conferences and events. For publication in a future issue, send your diary dates to: Carrieann Stocks, IWP&DC, Global Trade Media Ltd, Progressive House, 2 Maidstone Road,

Foots Cray, Sidcup, Kent, DA14 5HZ, UK. Alternatively, email: [email protected], or fax:+44 208 269 7804

DIARY OF EVENTS


DIARY

August8-11 August7th Brazilian Symposium on Geotechnical and Geoenviron-mental MappingMaringá, Brazil

CONTACT: Universidade Estadual de Maringá, Brazil.Tel: (0055) 44 3011Fax: (0055) 44 3011- 4731Email: [email protected]

16-20 AugustHydropower AfricaJohannesburg, South Africa

CONTACT: Spintelligent (Pty) Ltd, PO Box 321, Steenberg 7947, South Africa.Tel: +27 21 700 3500.Fax: +27 21 700 [email protected]://www.spintelligent-events.com/hydropower2010/en/online-registra-tion.php.

25-27 August35th Conference on Our World in Concrete and StructuresSingapore

CONTACT: Conference Secretariat, CI-Premier Pte Ltd, 150 Orchard Road, #07-14, Orchard Plaza, Singapore 238841,Tel: +65 6733 2922.Email: [email protected].

30 August - 3 SeptemberECEE 2010 (14th European Conference on Ear thquake Engineering)Ohrid, Macedonia

CONTACT: MAEE (Macedonian Associat ion of Earthquake Engineering), 73 Salvador Aljende, PO Box 101, 1000 Skopje, Macedonia.Tel: +389 2 3 107 701.www.14ecee.mk.

September12-16 September21st World Energy CongressQuebec, Canada

CONTACT: Organsing Committee, 740 Notre-Dame Street West, 8th

Floor, Montréal, Québec, Canada H3C 3X6.Tel: + 1 (514) 397-1474.www.wecmontreal2010.ca.

15-17 SeptemberAfrican Hydro SymposiumArusha, Tanzania

CONTACT: African Hydro Symposium, PO Box 32774, Lusaka 10101, Zambia.Tel: 260 211 371 007.Email: [email protected].

19-23 SeptemberDam Safety 2010Seattle, WA, US

CONTACT: Association of State Dam Safety Of!cials (ASDSO), 450 Old Vine Street, Lexington KY 40507, US.Tel: +1 859 257 5140.Fax: +1 859 323 1958.Email: [email protected].

22-23 September8th ICOLD Euopean Club Sympos ium: Dam Sa f e ty - Sustainability in a Changing EnvironmentInnsbruck, Austria

CONTACT: IECS2010 Organizing Committee, Stremayrgasse 10/II, A-8010 Graz, Austria.Fax: +43 316 873 [email protected].

27-29 SeptemberHydro 2010Lisbon, Portugal

CONTACT: Hydropower & Dams, Aqua~Media International Ltd, PO Box 285, Wallington, SurreySM6 6AN, UK.Tel: +44 (0)20 8773 [email protected].

27 September - 2 OctoberSmall Hydro ResourcesTrondheim, Norway

CONTACT: International Centre for Hydropower (ICH), Klaebuveien 153, N-7465 Trondheim, Norway.

Tel: +47 73 59 0780.Email: [email protected].

28-30 September2nd International Congress on Dam Maintenance and RehabilitationZaragoza, Spain

CONTACT: Daniel Ariza, TILESA OPC, Londres, 17 - 28028 Madrid.Tel: +34 91 361 2600Fax: +34 91 355 [email protected]://www.damrehabilitationcon-gress2010.com

October13-14 OctoberBritish Hydropower Association Annual Conference 2010Glasgow, UK

CONTACT: Ellan Long, British Hydropower Association, Unit 6B Manor Farm Business Centre, Gussage St Michael, Dorset, BH21 5HT UKTel: + 44 (0)1258 840934.Email: [email protected].

17-19 OctoberPower Generation & Water Abu Dhabi, United Arab Emirates

CONTACT: IIR Middle East, Dubai, United Arab Emirates.www.powerandwaterme.com.

19-21 OctoberEFEF 2010 (European Future Energy Forum)London, UK

CONTACT: Turret Middle East, ADNEC House, PO Box 94891, Abu Dhabi, United Arab Emirates.www.europeanfutureenergyforum.com/home.

25-29 OctoberRisk Management in Hydropower DevelopmentTrondheim, Norway

CONTACT: International Centre for Hydropower (ICH), Klaebuveien 153, N-7465 Trondheim, Norway.Tel: +47 73 59 0780.Email: [email protected].

November24-26 November16th International Conference on Hydropower PlantsVienna, Austria

CONTACT: Dr. Eduard Doujak, Institute for Waterpower and Pumps, Karlsplatz 13/305, ViennaAustria, [email protected]

26-28 NovemberWorkshop on Optimization of Construction Method for CFRDsYichang, China

CONTACT: HydrOu China.Tel: +86717 672-1379Email: [email protected]://www.hydrou.com/index.php?option=com_content&task=view&id=166&Itemid=1

February 201115-17 February6th International Conference on Dam EngineeringLisbon, Portugal

CONTACT: Eliane Portela, LNEC, Concrete Dams Department, Av. Brasil 101, 1700-066, Lisbon, Portugal.Tel: (351) 218443361.Email: [email protected]://dam11.lnec.pt.

May/June 201129 May - 3 June79th Annual Meeting of ICOLDLucerne, Switzerland

CONTACT: Swiss Committee on Dams, c/o Stucky Consulting Engineers, 33 Rue du Lac, Case Postale, CH-1020 Renens, SwitzerlandEmail: [email protected]://www.swissdams.ch

14-17 JuneIHA’s 2011 World CongressIguassu Falls, Brazil

C O N T A C T : In t e rna t i ona l Hydropower Association.Tel: +44 20 8652 5290.Email: [email protected]: www.hydropower.org.

Here you will find details on some of the executive appointments made by companies within the hydro power and dams industry over the past few months. To submit details of appointments for publication in a future issue of the magazine,

please send an email to the editor, Carrieann Stocks, at: [email protected]

EXECUTIVE MOVEMENTS

APPOINTMENTS


New CEO for Hydro Tasmania

Hydro Tasmania has announced its new CEO, Roy Adair took up the position on 21 June 2010.

Hydro Tasmania Chairman Dr David Crean said Adair has extensive national and interna-tional experience at the highest level in the energy industry.

Ada i r was Pres ident and CEO of Senoko Power Ltd, Singapore’s largest integrat-ed electricity generation and retail supplier for six years to November 2009. Previously he was Chief Operating Officer for Pacific Hydro, one of Australia’s leading renewable energy busi-nesses and a major player in the development of the national wind industry.

Dr Crean said Adair brought a wealth of experience to the posi-tion and was the best person to lead Hydro Tasmania as it sought to build on its position as one of Australia’s leading inte-grated energy businesses.

A d a i r ’ s p r e v i o u s r o l e s include:

Australia - July 1999 - January 2001

Energy - April 1996 - June 1999

He is a graduate economist and a qualified accountant and is currently a Board member of the Centre for Energy and Greenhouse Technologies.

BC Hydro appoints president and CEO

BC Hydro has appointed Dave Cobb the new president and chief executive of!cer of BC Hydro.

“Dave comes to BC Hydro with a strong mix of business experience, senior leadership skills, and man-agement of major projects,” said Dan Doyle, Chair of BC Hydro’s Board of Directors. “His strategic thinking and issues management experience will be a great !t for BC Hydro. I am con!dent that under

his leadership we will deliver the many objectives outlined in the recent Clean Energy Act.”

Cobb recently served as the executive vice-president and deputy CEO of the Vancouver Organizing Committee for the 2010 Olympic and Paralympic Winter Games (VANOC), where he was respon-sible for leading a broad portfolio, including games operations, !nanc-es, revenue planning, and commu-nications. Prior to joining VANOC, he spent 12 years with Orca Bay Sports Entertainment (Vancouver Canucks), including senior roles as chief operating of!cer and chief !nancial of!cer.

“This is a very exciting time in BC Hydro’s history and the future of our province and I look forward to the challenges and opportunities that lie ahead as we implement the province’s ambitious new Clean Energy Act,” said Cobb.

Mott MacDonald expert appointed visiting professor at the University of Southampton, UK

-able energy director, Dr Simon Harrison, has been appointed as visiting professor at the University of Southampton at the School of Electronics and Computer science. As part of his role, Dr Harrison will lecture on electrical engineering at the university as well as participate on an industrial panel.

Dr Harrison, who is based at

in Brighton, plays a key role leading the consultancy’s renewable energy business in the UK and internation-

is playing key roles in major projects

power scheme in Pakistan, off-shore wind farms across Europe,

one of the world’s most sustain-able urban developments in Abu Dhabi.

Dr Harrison has a long history with the university, having studied for both his BSc and PhD degrees, he was also a full time member of the academic staff for several years at the University of Southampton’s

Electrical Engineering Department. Commenting on his appointment,

Dr Harrison said, “The University of Southampton is renowned for both its research and teaching activ-ity in electrical power engineering. It is a great privilege to be part of such an institution again and re-establish my connections.”

Dr Harrison is chairman of the Institution of Engineering and Technology Energy Sector Panel and a fellow of the Energy Institute.

Deritend appoints non-executive chairman

Deritend Industries – a UK based industrial maintenance, service and repair group – has announced the appointment of David Garman as non-executive Chairman with immediate effect.

The company, with headquar-ters in Wolverhampton, operates from a national branch network. The appointment comes close on the heels of a recent multi-million pound investment in the company and will support the ‘ambitious growth strategy’ for Deritend,

“With David on board and sup-ported by this investment,” he said, “we are looking to consolidate our core markets, further develop our product offering and ramp up our energy efficiency services for customers across the spectrum of British industry.

“David is a key !gure in a range of industry sectors, with a proven track record of achieving rapid and sustainable growth,” continued Hale. “He will be a valuable asset to the company, with the knowledge and experience to help us imple-ment this planned expansion.”

Garman’s experience includes spending nine years as Chief Executive of logistics group TDG, which he held from 1999 until the company’s takeover in 2008.

Prior to TDG, Garman spent 20 years at United Biscuits in a range of management roles and was a direc-tor and chief executive of Allied Bakeries, a subsidiary of Associated

include non-executive director of Phoenix Group plc and non-execu-

tive director of Carillion plc, where he is also senior independent director. Garman is also an Associate of Duke Corporate Education and a Business Adviser for Enterprise Ireland.

Duke Energy names President of Indiana operations

W. Reed president of its Indiana service region. Reed will be respon-sible for the company’s Indiana regulatory work, governmental relations, and economic develop-ment and community affairs.

He replaces Jim Stanley, who is transitioning to senior vice president of power delivery for the company’s US operations. Reed is currently commissioner of Indiana’s Department of Transportation. He will join Duke Energy on June 14.

Reed, of Cicero, has led the

where he was responsible for approximately 4,000 employees and a $2 billion annual budget to construct and maintain the state’s road system. He reported to

and is a member of his cabinet.Prior to his work with the state,

Reed held various leadership posi-tions at GTE/Verizon. He was the senior state executive for the Indiana, Texas and Kentucky operations. In that role, he had overall responsibility for customer service, delivery, construction, maintenance, large and medium customer account management, budgets, and regulatory and legis-lative relations.

Early in his career at GTE, he was the first quality director for the company’s largest subsidiary,

Additionally, he directed annual revenue and expense budgets of more than $1B as budget and finance director for GTE’s

Reed has a broad base of util-ity experience. He served as execu-tive director of the Indiana Utility Regulatory Commission from 2006-2009, where he managed the com-mission’s electricity, water, sewer, natural gas, pipeline safety and con-sumer utility industry divisions.


INSIGHT

THE economic downturn has changed the contract delivery methods for many infrastructure projects in Europe, the Middle East

and Africa (EMEA). An example of which is a trend of fewer cost-reimbursable contracts and more lump sum contracts. Additionally, public private partnership delivery is being implemented on many infrastructure projects, and even recent hydropower projects have seen governments tender for private con-cessionaires to design, build, operate and transfer these projects. As contract delivery methods change, it transfers the risk alloca-tion between the parties, which should be considered in the risk assessment and affects the structure of disputes.

Recent industry trends indicate that construction disputes are on the rise. Additionally, owners and contractors are continuously trying new, alternative methods of dispute resolution to minimise the time and cost to settle their disputes.

In general, disputes are driven by change, regardless of a project’s geographic location. Additionally, changes in construction today are still driven by the same common project conditions that have driven changes in recent decades, such as differing site conditions, errors and omissions, owner-directed changes, etc.

What has changed as a result of the cur-rent economic conditions and political envi-ronment is the way projects are approached, executed and managed. More focus and exposure appears to be directed at the pre-planning phases, which heightens the need for a transparent risk management pro-gramme. Owners are looking more aggres-sively at ways to better manage costs, while contractors are actively seeking options to protect or improve tighter pro!t margins.

H"#$%&%'($ &$%)(*+, Marsh Construction Consulting profession-als have been engaged in numerous hydro-power projects in Europe and Asia. These projects range from combined irrigation and hydroelectric projects to hydropower programmes of multiple power generation stations. Additionally, our experience has included consulting for both developers and contractors, providing services throughout the project life cycles. This has allowed a balanced perspective in identifying con-struction risks during development phases, resolving disputes during negotiations, and in some cases providing expert analysis and

testimony in International Chamber of Commerce (ICC) arbitration.

As an indication of a representative engagement, Marsh consultants were retained on a hydropower plant that was a joint implementation project between two European countries within the framework of the Kyoto Protocol. The project had some unique aspects as it was designated as a pilot project located in a mountain range at a country border, and was to be part of a string of power stations along the nearby river. The above-ground storage power sta-tion had an installed capacity of 80MW and a standard production of 185GWh/yr, while the reservoir had a volume of 111Mm3 and was contained by a 125m high arch dam.

The conventionally driven intake water tunnel partly cut across a geologically problem-atic zone. While all projects contain their own unique issues, the political pro!le and challeng-ing site conditions added an element of risk for which Marsh professionals were engaged to analyse and identify areas of impact, delays, and potential risk for the project.

The need for risk assessments for these infrastructure projects varies signi!cantly; based on the types of projects and the capac-ity in which these assessments are conducted. For example, in one particular engagement, Marsh Construction Consulting profession-als led a risk assessment and contractor esti-mate validation exercise of a multi-billion US dollar landmark submersible -ood gate system in Italy. In this case, the need was for a detailed quantitative risk assessment of the cost to complete the ten-year programme. From this assessment, we were able to pro-vide a speci!c recommendation on the appro-priate allocation of risk in the EPC contract and determine the appropriate range of con-tingency for the programme. Studies such as this are often used as the basis to approve funding for unique ‘one-of-a-kind’ projects.

I.,/$0.*( *1023,Speci!c industry expertise has proved valu-able in assisting with insurance claims related to hydro construction projects. For example, to address a force majeure event (-ood) on a hydroelectric station in Asia, Marsh formulat-ed a written acceleration plan for submission to the insurers. This plan speci!cally outlined the parameters and components of the mitiga-tion and recovery of the time impact of the force majeure event on project completion.

In order to adequately address these

speci!c needs of owners and contractors for risk assessments and claims services, signi!-cant expertise across multiple disciplines is required. Additionally, to continue to add value to hydropower and dam clients, it is imperative that construction professionals stay abreast of the dynamic environment in which these projects develop. While this can prove challenging, it’s also a very interesting time for !nding hydropower solutions, given the current focus on renewable energy and environmental concerns.

&$%)(*+ *%.+$%1, It has always been good practice to imple-ment reliable project controls and project governance methods for large, complex con-struction projects. However, today’s dynam-ic political and economic environment has placed an increased emphasis on hydropower projects in particular. When these factors are combined with balancing the world’s grow-ing energy needs with an intense focus on renewable energy sources and environmen-tal concerns, creative solutions are needed to address these challenges.

One could say there’s less room for error in this environment, or put another way, it will be more costly to address changes or risks that are not identi!ed and mitigated early in the project life cycle. Additionally, ensuring that the best practice project controls and governance procedures are in place for a par-ticular project is not enough. It is becoming more and more important to ensure proper implementation of these controls at every step throughout execution.

Most will agree the level of scrutiny in which these projects are designed, built, and operated has increased in the last decade. The need for improvement goes beyond advanc-ing the methods of execution with technol-ogy improvements. It means understanding how risks are transferred amongst the parties throughout the project life cycle, as contract delivery methods, funding mechanisms, and stakeholder needs continue to evolve. It’s not just the project success goals that have changed in the last decade, but the ways in which we achieve those goals and the tools we have developed to ensure transparency and control throughout the life cycle.

Todd Vandenhaak is Leader of the Construction Consulting Practice for

EMEA at Marsh Risk Consulting. Email: [email protected]

Constructive consultationThe current economic conditions and political environment have changed the way that construction projects, such as hydropower, are approached, executed and managed. Todd Vandenhaak gives an insight into why more construction consulting is now required

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SMALL HYDRO

A SIMPLIFIED history of hydropower in the New England area begins hundreds of years ago as small mill owners harnessed the energy available in falling water and convert-ed it to usable mechanical power. Later, this energy was

converted to electricity and by 1940 approximately 40% of the US’ electrical demand was met through hydroelectric generation. With the increased use of inexpensive fossil fuels, the majority of these smaller hydropower facilities were eventually left to ruin. Today in a seemingly endless quest for renewable energy, we have returned to our roots and the hydropower boom has once again begun.

There are many challenges associated with small hydropower devel-opment. For those involved in the industry it will be no surprise to see regulation discussed !rst. However, there are other important challeng-es such as acquiring the initial capital investment, overcoming market instabilities, and for now let’s say !nding some ‘Yankee Ingenuity’.

REGULATIONS

With few exceptions, new hydropower is heavily regulated under the Federal Energy Regulatory Commission (FERC). The process of obtaining permission to construct, maintain and operate a hydroelec-

tric plant through the means of a licence or exemption document is typically a lengthy and expensive process. Pursuant to 18 CFR 4.38 and 5.1 (d), and 16.8, an applicant seeking an exemption or licence must consult with relevant federal, state, and interstate resource agen-cies, Indian tribes, and non-governmental agencies.

Comments and suggestions by these stakeholders can be in refer-ence to !sh and wildlife mitigations but also extend to historic con-cerns, recreational issues, and the aesthetic impact of the project on the surrounding area. Furthermore, there are provisions that licences for hydroelectric projects must include conditions to protect, mitigate damages to, and enhance !sh and wildlife resources.

Speci!c project conditions required for a hydro plant are deter-mined through a stakeholder consultation process, which typically includes a series of costly studies. The results may not only indicate measures to reduce impacts during construction but also permanent operations measures that may reduce the overall annual energy gen-eration of the project.

In general the small hydropower community in New England is a tight group of hard working folks who are environmentally con-scious. They support fair-minded measures which assist them in con-structing and operating their sites in a manner that is environmentally

Siblings Celeste and William Fay have a long history and unique perspective in the small hydro industry. Here they share their

experiences and explain how the endless quest for renewable energy is prompting a renaissance for small hydro in the US

Small hydro renaissanceProspecting potential micro-hydro sites in New Hampshire, Site pictured is a 100 hp turbine directly connected to an air compressor


SMALL HYDRO

friendly. The heart of the issue is very simple. Why does a proposed 50kW hydroelectric project at an existing dam site, with minimal additional environmental consequences, go through the same lengthy and expensive process as a new 5MW site? Why isn’t there a stream-lined process for non controversial projects or low impact projects?

To be fair, FERC itself held a workshop in December 2009 on small non federal HEPs where these same questions were asked. The cumulative results were summarised in a FERC press release from April 2010 which stated that the commission is working to ease the regulatory burden of small hydro regulations through developing new online resources, creating simpli!ed licence/exemption application templates and improving coordination with resource agencies.

FINANCE ISSUES

Acquiring the initial capital investment and overcoming market instabilities to be able to develop small hydropower are intertwined issues. Sometimes it is possible to obtain a !xed power sales con-tract. However, more likely than not, the energy generated is sold to a larger electric company based upon ISO New England open market rates. In other words, the value of the energy is based upon supply and demand, which is subject to wild "uctuation and can be dif!cult to predict.

French River Land Co (FRLC) in Ware, Massachusetts owns the Tannery Pond HEP that sells energy to National Grid for open market rates. FRLC receives a spreadsheet on a monthly basis that details, on an hourly basis, the amount of energy generated and the corresponding rate. It is not unusual to see the value of energy reach a high of US$300/MWh but a low of US$0MWh. As an example, for the ISO New England central/western Massachusetts zonal area, the average value of energy for this year to date (June 2010) is around US$48/MWh. However, having a potential value of US$0/MWh does not typically make a !nancial institution feel comfortable lending a developer the funding required to get the project off the ground.

Renewable energy certi!cates (RECs) have assisted in this area. Typically, a !xed value contract for the RECs is signed for a year or more. However the average value in the New England area is only around US$20-30/MWh for !nancing purposes.

YANKEE INGENUITY

Now we come to the Yankee Ingenuity. Large hydropower produc-ers have the luxury of additional monetary resources, which means that there is more room for outsourcing of engineering and construc-tion services. The small hydro producer must be more careful in this respect, be able to evaluate available resources and make them work to their advantage. If we look at sites that are making an average annual energy generation between 100MWh/yr and 2000MWh/yr

and assume an average energy value of US$50/MWh with an addi-tional US$30/MWh in RECs, the average annual value of the site’s energy is approximately US$16,000 and US$160,000.

Some costs such as environmental studies, engineering, and con-struction materials are more or less !xed; therefore, others must be minimised to the extent possible for a small project to be !nancially viable. Depending on how one looks at it, the opportunity or chal-lenge here is in planning and designing a site to use existing structures and equipment.

In New England, a new dam is very dif!cult to construct and really is not a necessary requirement. With tools such as Google Earth and GIS data, the ability to !nd existing, unused dams has been greatly enhanced. Many old mill sites still have extensive civil works such as penstocks, powerhouses or tailrace structures. Of course, it is rare to !nd these structures in a state such that they do not require some rehabilitation. Yet often, a simple economic analysis will show that using these structures will drastically increase the economic viability of small hydro.

Additionally, many hydroelectric facilities today are generating using equipment that is almost 100 years old and with a surprisingly high ef!ciency. Whether it is the equipment found on-site or procured from somewhere else, used equipment is not something that the small hydro developer should overlook even if it requires rehabilitation. A small hydro site does not necessarily require all the bells and whistles and will likely not be economically successful if anything other than the bare minimum is installed.

For example, a colleague of ours uses a simple mechanism consist-ing of a rope, pulley, telephone repeater, and weighted paint bucket as a regulating mechanism for the governor on his turbine and it works great. This approach is not for everyone but if the average annual generation of a site is below a certain threshold, this kind of plan of attack is critical to success. It should be noted that the primary goals of some developers is not to generate an income stream. Companies may be looking to meet green goals or to preserve their long-term sustainability by offsetting their electrical demand with renewable energy. These folks will still !nd bene!t in using Yankee Ingenuity but it may not be quite as critical.

RIght: Will moving the Tannery Pond turbine; Below: 18 Inch Rodney Hunt Type 60 being rehabilitated for the Tannery Pond HEP Grant; Below right: Celeste rigging a 640kW generator into a rehabilitated HEP


SMALL HYDRO

REPOWERING SITES

This is the business model that we have built as a result of our limited economic resources and our abundance of hydropower knowledge. We became involved in hydropower at a young age because we grew up in and around hydroelectric power plants. When we were chil-dren, our father would bring us to various HEPs and we would do small tasks to assist with both engineering and hands-on site reha-bilitation tasks. As we gained more of a grasp on exactly what it was that we were doing, we gained more interest and enthusiasm for the hydroelectric !eld.

Towards the end of our high school careers, our father and his partner had acquired larger power plants in the 1200kW to 4000kW range. The Tannery Pond hydropower station in Winchendon, Massachusetts was originally licensed for 189kW and it was quickly becoming obsolete in comparison to a 4000kW project. We wanted to become more involved in hydropower and eventually took over French River Land Company and the Tannery Pond HEP. The Tannery Pond facility had not produced electricity prior to us taking over the project. The station posed many challenges but we perse-vered and were able to repower the site.

When we took over the Tannery Pond project, the station had a FERC exception, an interconnection, two non-operational turbine-generating units and all the necessary civil works such as the dam, intake, trash racks, and powerhouse. The !rst unit was a Rodney Hunt 96cm diameter runner, type 80 Francis turbine, coupled through a 200hp Paramax 90 degree gearbox, to a 150hp-1800rpm induction generator, which had the potential to produce 80kW on the 3.4m of available head. The second unit was originally a homemade

turbine that had poor design characteristics. The turbine could not operate ef!ciently and was removed.

In 2009, FRLC obtained a US$461,000 grant through the Massachusetts Technology Collaborative to install two remanufactured Francis turbine-generating sets and computer controls in the Tannery Pond plant. This work will be completed by the end of 2010.

Around the same time, we removed a Leroy-Somners, Hydrolec, semi-kaplan turbine from a mill in New Hampshire. The turbine, hel-ical gearbox, and generator are located within an oil-pressurised bulb, in a "anged pipe section, mounted on a penstock. The unit was thor-oughly dilapidated and required a full rehabilitation. Unfortunately, parts and mechanical speci!cations for the unit were not available. It took almost a year of part-time work to rebuild the unit with new roller bearings, gears, and various other parts. The rehabilitation was completed in 2005 and the site successfully produced electricity.

SEARCHING FOR SMALL HYDRO

During the same period we were looking for other small hydroelec-tric projects. Our limited !nancial resources restricted us. However, we located a potential project on the Squam river in Ashland, New Hampshire, which we were able to purchase through the graces of owner !nancing in 2005. The Ashland hydroelectric project is an 84kW FERC licensed project constructed in 1984. The station had originally been under a generous power sales contract from the 1980s that set the value of energy at about US$20/MWh; but this had expired previous to our purchase.

We were fortunate though to negotiate a power and sales con-tract with the Ashland Light Department, which included provisions for the department to conduct limited operations. The station has a Leroy Somners, Hydrolec tube turbine, rated at 84kW on 5.5m of net head. The unit had been struck by lightning, disassembled, and left in a !eld for almost !ve years.

Our 18-month part-time rehabilitation of the turbine included the replacement of just about every mechanical and electrical component in the unit. A fair amount of guesswork was involved since no parts, plans, or speci!cations were available from the original equipment manufacturer. But with the use of our father’s machine shop, we were able to repair the unit and it began generation in November of 2007.

ENJOYING THE CHALLENGE

As our skills and knowledge expanded, our involvement in the engineering portion of hydroelectric power plants also expanded. We both enjoy the challenge and joy of sharing our hydroelec-tric knowledge with others by !nding economical solutions for the development of small hydropower throughout New England. There is once again a small hydro renaissance occurring not only in New England but also throughout the county and it is an excit-ing time to be involved in the industry.

Celeste N. Fay, GZA Geo-Environmental, Email: [email protected] and William D. B. Fay, French

River Land Company. Email: [email protected] www.frenchriverland.com

View of Ashland hydroelectric project

IWP& DC

Technical data on the FRLC projects

Tannery Pond Ashland

Dam type Gravity Dam Gravity Dam

Dam material Laid !eldstones Concrete capped granite blocks

Dam length 125ft 80ft

Dam height 6ft 12ft

Spillway type Over"ow weir w/"ashboards

Over"ow weir w/"ashboards

Year constructed 1913 1925

Impoundment surface area

8 acres 12 acres

River Millers Squam

Drainage area 49 square miles 67 square miles

Average flow 92 cfs 88 cfs

Average annual minimum flow

4 cfs 15cfs

Bypass reach length 760 ft 320 ft

Minimum bypass flow 21 cfs 32 cfs

Installed capacity 189kW 84kW

Turbine type Unit 1 – 38” Rodney Hunt Type 80, Unit 2 – 48” Leroy Somners Semi-Kaplan

Unit 1 – 36” Leroy Somners Semi-Kaplan

Generator type Unit 1 – 1800 rpm induction generator, Unit 2 – 900rpm induction generator

Unit 1 – 1800 rpm induction generator

Hydraulic capacity 230 cfs 79 cfs

Average annual generation

510,000kWh/yr 420,000kWh/yr

Regulatory status FERC exemption from licensing

FERC exemption from licensing

Turbine & Alternator Manufacture

Turbines up to 20 MW

Alternators up to 22 MVA

Governors

Switchboards

Am Stollen 13

79261 Gutach/Germany

Tel. + 49 7685 9106 - 0

Fax: + 49 7685 9106 - 10

www.wkv-ag.com

Water-to-Wire Solutions Made in Germany

WKV_86x134_E_4c_RZ 07.07.2010 12:37 Uhr Seite 1

Liquid Energy – Solid Engineering

gugler 31/3/09 14:10 Page 1


SMALL HYDRO

FOR many families around the world, access to modern energy is a pipedream. People are forced to cook on open !res that !ll their homes with toxic smoke and as the light fades each evening so too does the possibility of adults

working into the evening, children studying, and families cooking safely in well-lit, clean homes.

This lack of access to energy traps people in a constant cycle of poverty that they unable to break free from.

Over 1.6B people – almost one third of the world’s population – have no electricity. In Africa four out of !ve families live without electricity, according to international development charity, Practical Action.

CHANGING LIVES

Practical Action believes that the right idea, however small, can change lives. The charity works with some of the world’s poorest women, men and children helping to alleviate poverty in the developing world through the innovative use of technology and facilitating access to energy for poor communities through a variety of means, enabling them to lift themselves out of poverty and change their lives.

The charity was founded in 1966 by radical economist E.F. Schumacher who strongly believed in using small scale, low cost and appropriate ideas to change people’s lives and that ethos still rings true today. Speci!cally, Practical Action is working to imple-ment small scale renewable energy schemes in rural communities that aren’t linked to the national grid. It is enabling them to be involved in the construction and management of renewable projects

and provide a sustainable source of energy for the !rst time that will safeguard future generations.

MICRO HYDRO SYSTEMS

Practical Action has developed small scale micro hydro schemes with communities in Peru, Nepal, Sri Lanka, Kenya and Zimbabwe as well as in Nicaragua, Guatemala, El Salvador, Bolivia, Mozambique and Malawi as part of the charity’s extension work from its country of!ces. These systems, which are designed to operate for a minimum of 25 years, are usually run-of-river systems.

A system with a capacity of 6kW is big enough to drive a mill and provide electrical lighting for up to 20 families.

As well as driving a generator to provide electricity, micro hydro is also used in these areas to supply power to remote villages via recharge-able batteries that can be used for lighting and to play small radios and power TV sets. Lighting is one of the basic needs of poor people and they can have much better and safer lighting at a lower cost through the use of this technology by replacing candles and kerosene lamps.

Practical Action is different to other development charities in that it uses a participatory approach in all of the work that it carries out in the communities. Engineers from the charity will enter a community, assess its needs and resources and also determine the most appropriate technology for the particular conditions. When micro hydro is decided upon as the best option, decisions will be made following calculations to determine the most appropriate materials to use and how much the scheme is going to cost based on the number of families it needs to

Bringing water power to the poorDevelopment charity Practical Action believes that the right idea, no matter how small, can change lives. Here Teodoro Sanchez shows how micro hydro schemes are helping to transform lives around the world

Civil engineering for a micro hydro system in Bocatoma, Peru


SMALL HYDRO

serve, the potential growth of the community and their possible eco-nomic development. It’s also necessary to assess the capacity of the country as to whether national industry can produce equipment and components that will !t the needs of the project or is already produc-ing them. If it is the case that presently there is not such a capacity, Practical Action provides technology and technical assistance to enable local manufacturers to produce the equipment required.

Once a technology is decided upon and manufactured, the tech-nology is implemented and then the training begins. Members of the local community will be selected in a participatory manner and trained to manage the operation and maintenance of a micro hydro system and the community must decide how they will pay for its upkeep – repairs, replacement components etc. A tariff scheme will be devised by the community with Practical Action’s help, ensuring that the scheme will be sustainable and last for many years to come.

CASE STUDIES Chipendeke, ZimbabweOne such project has recently been implemented in Chipendeke, Zimbabwe, situated along the Wengezi river. This micro hydro scheme provides 25kW of electrical power which serves almost 130 families. This quantity of energy provides enough electricity for domestic needs such as lighting, as well as providing power to a health centre, school and numerous small businesses being run by community members.

The cost of this scheme ran to Euros 87,000 (US$108,000) and 85% of the cost was part funded by the EU. The other 15% was funded by the community contributing with labour and local materi-als. With the initial investment taken care of, the community is only left responsible for paying for management and maintenance of the system which consists of a small payment each month.

Chorro Blanco, PeruChorro Blanco is an isolated community in the Cajamarca region of the Peruvian highlands. The cost of rural electri!cation through the national grid would probably have meant that Chorro Blanco remained without modern energy for many generations. The supply of micro hydropower provided electricity for 60 rural families and 90 families from neighbouring villages for the !rst time in their lives. The scheme provided electricity for domestic and public lighting, small businesses and battery charging.

The scheme comprises the intake weir, conveyance ditch, settling basin and forebay tank, penstock and anchors, powerhouse and dis-charge channel. The local community is also making a sizeable con-tribution to the manpower requirements of the project, transporting materials to the site and assisting with labour.

This scheme generates 20kW of electrical power; it uses a locally made Pelton turbine, a penstock made of PVC and an electronic load control-

ler. The electricity is transported from the powerhouse to the village using 1.6km mid-tension lines and set-up and step-down transformers.

CHALLENGES

Working with poor communities, and sourcing materials, within a developing country presents a number of social and cultural obstacles to Practical Action staff when implementing micro hydro schemes. The poverty of the families involved leads to issues with funding par-ticularly when there is no outside investment from local governments or bodies, and many families can struggle with budgeting for mainte-nance payments for their systems.

In rural communities that use energy sources such as kerosene or biomass for their needs, fuel is typically purchased in small quanti-ties. Families have never needed to budget and commit to a regular monthly payment which can be a dif!cult concept to adapt to but is essential to ensure the sustainability of the schemes. To resolve this, extensive training is undertaken within the communities to explain the costs and implications of sustaining a micro hydro system.

THE FUTURE

Practical Action works continually with staff based in its country of!ces identifying opportunities and communities that can bene!t from small scale renewable energy schemes. The charity works to engage with local governments and decision makers to source funding and continue its work. Practical Action adopts a ‘bottom-up’ approach where local gov-ernments are encouraged to learn from the technologies implemented, adopt them and replicate them across the country once they can see the difference they are making to people’s lives.

GET INVOLVED

Practical Action is currently campaigning for ‘energy for all’ by 2030. Modern energy transforms lives; improves health and education and lifts people out of poverty. The charity will be developing a group of energy ambassadors towards the end of the year, to !nd out more email [email protected] .

Teodoro Sanchez is an Energy Technology and Policy Adviser at Practical Action.

Email: [email protected].

For more information about Practical Action’s work in renewable energy around the world please visit

www.practicalaction.org.uk.

Children use electric light provided by the micro hydro system to study after dark A woman sits by the forebay tank for a new micro-hydro system, Peru

IWP& DC


SMALL HYDRO

TAPPING into the wasted energy of public water systems doesn’t typically generate large amounts of power: a few hundred kilowatts at best. On the other hand, the exist-ing infrastructure already provides almost everything

needed for a hydro system except the turbine/generator set. Public utilities routinely bleed off excess pressure that could be put to work simply by opening a coupling and bolting in a turbine. Even though power output may be nominal, this low cost solution can quickly pay for itself.

Unlike most hydro systems, however, energy recovery systems are often subject to unusual constraints. For example, community water usage directly affects !ow, which can vary dramatically over the course of a day. In addition, it is often necessary to maintain water pressure at the turbine output to ensure adequate pressure for the community. These factors can complicate the selection of turbine equipment.

It is also important to remember system priorities. The highest pri-ority is uninterrupted water supply to the community, with power generation coming in a distant second. These priorities can collide at times. For example, if an electrical problem abruptly trips the genera-tor of!ine, water must continue to !ow to the community even though the turbine/generator may be suddenly freewheeling under no load.

Beyond technical issues, regulatory hurdles can significantly delay an energy recovery project, if not kill it entirely. Conventional wisdom would suggest approval would come quickly, since the entire system is usually a simple revision of plumbing. But these low impact projects are subject to the same regulatory processes as larger scale hydro systems, in the US requiring FERC permitting and – surpris-ingly – the need to deal with environmental opposition.

SOAR Technologies specialises in solving these types of problems for communities. The company provides specialised turbine systems, as well as assistance with feasibility assessment, technical design, and the long journey toward regulatory approval. Over the past few years, SOAR has installed energy recovery systems in Hawaii, Vermont, Oregon, and other locations across the US.

TECHNICAL CHALLENGES

Two major issues are commonplace with water supply systems: varia-ble !ow and pressurised distribution to the community. These factors create a challenging dilemma for hydro systems designers, especially when encountered on the same project.

Variable !ow, for example, would suggest the use of impulse tur-bines such as Pelton or turgo. With a broad ef"ciency curve, impulse turbines can often deliver good performance down to 10% of design !ow. But a pressurised output complicates matters. Impulse turbines, by de"nition, run in open air and typically employ a tailrace that is not easily pressurised.

In contrast, reactive turbine types such as Francis and Kaplan oper-ate well in a pressurized environment, since they are never exposed to the atmosphere. As long as there is a pressure difference between turbine input and output, reactive designs can produce power. Unfortunately, they are less forgiving of wide swings in !ow. Below 50% of design !ow, ef"ciency drops dramatically.

Then there is the issue of priority. By de"nition, community demand determines !ow rate; the power generation system cannot alter !ow in any way. Water must continue to !ow unimpeded even when the generator is suddenly thrown of!ine. Impulse turbines have the advan-tage here; a de!ector shield simply directs the stream of water away from the runner without affecting !ow. Reactive turbines are more of a challenge since the !ow of water always wants to spin the runner. In addition, the resistance of the runner itself has an effect on !ow.

All of the energy recovery systems installed by SOAR are designed to run in parallel with the existing water system. This allows the tur-bine/generator to be taken of!ine for maintenance without impacting the community water supply. Most systems use hydraulic actuators, allowing switchover to be manual or automatic.

DEVELOPING THE GPRVIn 2004, SOAR participated in a research project to develop a gen-erating pressure reducing valve (GPRV). SOAR worked with the

Energy recovery from public water systemsPublic water systems are often an ideal application for small hydro systems. The existing water supply provides a !nished intake and penstock, and in many cases a pressure reducing valve can be bypassed with a hydro turbine that generates a positive return on investment for the community. Michael Maloney reports.

A 35kW Pelton-type SOAR GPRV installed for the County of Hawaii Department of Water Supply


SMALL HYDRO

California Energy Commission and San Diego State University to develop a simple method for replacing existing PRVs with small hydro systems. Over the course of several months a number of work-ing test models were constructed to produce a preliminary design for a pressurised impulse turbine system. SOAR later patented this design for commercial production.

The original GPRV was essentially a Pelton turbine enclosed in a sealed housing to maintain positive pressure at the tailrace. As with all Pelton designs, the turbine runs in air, but the air is compressed within a sealed chamber. SOAR teamed with Canyon Hydro to man-ufacture this new design, and installed the !rst GPRV unit in a water system on the island of Hawaii.

This early version of the GPRV employed a vertical (horizontal shaft) Pelton runner, coupled with a standard air compressor to pressurise the system. The expected power output was achieved but there were signi!cant issues with air entrainment. Air in the water is not harmful; in fact, it tends to improve the water treatment process downstream. But since air must be compressed to run the system, and compressors require energy, any air loss down the pipeline is essentially a loss of ef!ciency. With the vertical runner design, the compressor was running almost constantly to replenish lost air.

To better manage air entrainment, SOAR engineers ran extensive computational "uid dynamics simulations, resulting in development of a new design that uses a horizontally-oriented (vertical shaft) Pelton runner for signi!cantly improved operation. Using a horizon-tal runner, the water tends to spin its way out of the turbine, helping to separate the air before the water exits down the pipeline.

SOAR has also developed reactive versions of the GPRV using Francis and reverse-pump designs. These fully immersed turbines simplify pressurised operation but are constrained to a much nar-rower operating range for changes in "ow. In addition, special provi-sions are necessary to accommodate continuous "ow even when the turbine trips of"ine.

Flow through a Francis turbine changes drastically when generator load is removed. A reactive turbine in an over-speed condition tends to choke "ow, an unacceptable scenario in a water supply system. To alleviate this problem, SOAR developed a multi-stage Francis design to maintain nearly constant "ow in any situation.

The SOAR Francis GPRV uses a modi!ed impeller design and uses two to !ve Francis runners in series. Head pressure determines the number of runners in the system. Because space is often at a pre-mium in existing water systems, runners are oriented vertically to save room. Unlike conventional Francis turbines, the water inlet and outlet are aligned to facilitate easy installation into an existing pipeline.

DETERMINING PROJECT FEASIBILITY

The growing global focus on green energy and sustainability has sparked a sharp spike in interest for energy recovery systems. Water supply systems are the most common application; however, there is also potential for wastewater system applications.

Wastewater systems are generally more dif!cult to cost justify. They tend to be low head, high "ow environments, which require physi-cally larger turbine systems to handle the additional "ow. Because physical size bears a direct relationship to turbine cost, SOAR has yet to evaluate a wastewater application that forecasts a positive return on investment.

When invited to assess the feasibility of a potential project, SOAR focuses on four key parameters: head, "ow, "ow duration (variabil-ity), and regulatory process. Most of our systems have been installed for use with a net metering plan, where generator output offsets some of the power normally purchased to run the plant. In effect, net meter-ing pays the power producer retail rates for electricity, substantially accelerating system payback.

Unfortunately, regulatory requirements are often a major obstacle.

Whenever public water and public power come together, approvals from both FERC and the local power company are required. Currently the lead time for gaining FERC approval of conduit projects is about six months, and the FERC application itself usually takes at least two months to prepare. Before submitting the application, multiple agencies, environmental groups, tribal leaders and other stakeholders must reach agreement.

Unfortunately, the cost to obtain regulatory approval sometimes makes it impossible to justify an otherwise viable project. But good news may be forthcoming. FERC has indicated that it will streamline and simplify applications for energy recovery projects.

Most of the inquiries SOAR receives originate from local water system operators. These are the hands-on water experts who know their systems and can identify opportunities for energy recovery. Even so, nearly every project requires buy-in at the executive level, and the cost must always be justi!ed. A good part of SOAR’s effort goes into pulling many disparate groups together to ensure project success.

LOOKING AHEAD

Worldwide interest in energy recovery appears to be growing, and SOAR anticipates more projects will emerge as word spreads between water districts. Green energy, despite the economic slowdown, still promises strong growth – especially on the heels of the disaster in the Gulf of Mexico. As technologies such as the GPRV continue to improve, and assuming the regulatory process is further streamlined, future energy recovery projects should be easier to justify and faster to implement.

Michael Maloney is president of SOAR Technologies, a hydropower design and project consulting !rm

based in Washington State, US. Email: [email protected].

www.soartechinc.com

Water

Water out

Water inAir in

Adjustableneedle valve

Deflector

Pressurizedchamber

IWP& DC

A line drawing of a Pelton-type GRPV. The SOAR Pelton-type GPRV pressuris-es a sealed runner chamber with compressed air to maintain water pressure at the outlet


TUNNELLING

BY last moth more than two-thirds of the Niagara power tunnel had been excavated by design-build contractor Strabag for Ontario Power Generation (OPG) using a hard rock TBM, which is driving along a realigned route fol-

lowing earlier geological dif!culties. All activities had resumed by June following a stop for maintenance and to launch the concret-ing work for the permanent arch lining over the tunnel invert.

The 14.4m diameter main beam TBM, manufactured by Robbins, had bored more than 7km of its 10.2 km long power tunnel route by early this month, says OPG’s project director, Rick Everdell. In its !rst quarter results, to 31 March, the utility reported that the TBM had advanced almost 6.5km – progress of 2.7km over the previous 12 months.

With the alignment having been raised by 45m, the TBM is out of the Queenston shale that had proven troublesome earlier in the project and the machine is mostly now meeting whirpool sandstone with tunnelling conditions further improving. “We are happy with the current rock conditions and ground support system, as we haven’t been short of challenges in the past,” said Strabag’s project manager, Ernst Gschnitzer.

Niagara Tunnel Project will be the third headrace below Niagara Falls and will help make use of the presently untapped allocation in Canada’s share of the water under the 1950 Treaty with the US. The 12.8m i.d. tunnel will convey a further 500m3/secs of water to the Sir Adam Back complex and add an extra 1.6TWh/year of electricity generation.

The TBM – ‘Big Becky’ – is the largest hard rock machine manu-factured and was also the !rst that Robbins assembled at a project site using its Onsite First Time Assembly (OFTA) system. The shield was launched in September 2006 to drive from the outlet and passed though 10 layers of near horizontal strata, comprising limestone, dolomite, sandstone and then reaching shale.

Originally, the Niagara Tunnel project was to have been completed by last month. However, extensive dif!culties with overbreak in the Queenston shale led to delays and safety concerns. OPG has noted that crown overbreak in the shale was up to 4m in depth into the

rock and averaged about 1.5m. Signi!cant modi!cations were needed behind the cutterhead to the initial support area for the excavated rock and worker safety.

The revised ground support system comprised spiles, rock bolts, mesh, steel straps and shotcrete. The grouted spiles are 9m long to help contain overbreak, and the rockbolts are 4m long, but in leaving the Queenston shale the need for the spiles lessened.

Last year the contract between OPG and Strabag was renegotiated and the tunnel realigned. The revised schedule is for the contract to be completed by the end of 2013 and the budget has been increased by about 60% to approximately Can$1.6B (US$1.5B).

Also last year, in the third quarter, a further rock fall happened but it was far back along the tunnel, more than 3km behind the TBM, in a stretch of tunnel that had previously suffered from problems of crown overbreak. No injuries were caused by the incident.

Work to re-complete the circular pro!le of the tunnel has now advanced to approximately 1.8km, notes Everdell. By the end of Q1, reported OPG, the arch lining had advanced 1km and by early May the activity had progresses a further 300m. Everdell adds that now there is almost no overbreak in the TBM drive with the crown in Grimsby sandstone about 7km along the route.

The secondary, !nal, lining for the tunnel will be formed of 600mm thick continuously-poured concrete on a waterproof membrane. Behind the TBM, almost 5km of the permanent lining for the invert had been completed by May, and the activity has resumed following the maintenance and outage activities. In its Q1 results, OPG said just over 4.5km of permanent invert had been placed by 31 March.

Concreting works, to place the upper two-thirds ‘arch’ of the per-manent lining over the invert began in late May, as planned, says Everdell, and the activity is making progress.

OPG said the current progress should have the project completed by the revised deadline and budget, possibly at less cost. The rene-gotiated contract has incentives on delivery against the revised target schedule and cost.

Progress is pushing ahead on OPG’s Niagara power tunnel after earlier geological dif!culties. By Patrick Reynolds

IWP& DC

Niagara progress

The Robbins Main Beam was the first ever TBM initially assem-bled at the jobsite using OFTA


TUNNELLING

EXCAVATION for the bypass tunnel at the top end of Glendoe headrace is underway to overcome a rockfall discovered almost a year ago, barely eight months after the 100MW hydro project began operations. UK contrac-

tor BAM Nuttall has been brought in to the project to excavate a short access adit and the water diversion tunnel.

The owner, Scottish and Southern Energy (SSE), said that a 900m long bypass tunnel is being bored by drill and blast but the scale of the recovery work for the project is unlikely to see the plant supplied and generating again before the middle of 2011 – almost two years after the problem was discovered.

In its 2009-10 Annual Report, issued in late May, SSE said that BAM Nuttall had been retained to drive the two tunnels and that work was already underway. However, no speci!c details have been given about the local geology, tunnel build or cause of the rockfall.

The Glendoe scheme near Fort Augustus, Scotland, has approxi-mately 16km of tunnel network, including the 6.2km long headrace. It was constructed under a design and build contract by the Hochtief Glendoe JV, led by Hochtief and including Poyry as the designer. The contract was awarded in late 2005. The client’s adviser is Jacobs.

Geology along the alignment of the headrace comprises quartz mica schist and quartzite with some minor faults. Most of the head-race was excavated using a 5.03m diameter open gripper TBM and some drill and blast, while the rest of the network was bored by drill and blast.

Depending on local ground conditions, four classes of support were available for the headrace ranging from minimum of rock bolts plus mesh and shotcrete, if needed, up to using all of those plus a steel set full ring. The UCS of the rock at the top end was 30MPa-130MPa. The successful tunnelling works were completed in early 2008.

When reporting the plant had to be shut down, SSE noted that no equipment had been damaged in the underground powerhouse as a consequence of the rockfall at the top of the headrace, which is fed by a reservoir. The plant has a single, six-jet vertical Pelton turbine and operates under a gross head of 608m with a "ow of 18.62m3/sec.

Investigations in August 2009 revealed the rockfall to be ‘very substantial’, said SSE. Then, it was anticipating that the plant might remain shutdown until well into 2010 at the earliest. But by then end of 2009 it had become clear the scale of repairs would have the plant out of action until well into 2011. The recovery options all required signi!cant programmes of work.

In a presentation to the British Tunnelling Society (BTS) during the construction phase, SSE noted that for risk management at Glendoe it had a degree of geotechnical risk on the project, three geologists on site, and the contractor’s tender was based on a ref-erence ground classi!cation system. It worked alongside the JV contractor, which produced its own design and was responsible for the tunnelling. IWP& DC

Above, top left: Inside the Glendoe tunnel works during main construction. Now, a bypass tunnel is being excavated by drill and blast after a rockfall near the top of the headrace following completion of the project; Above, right: TBM before launch to drive most of Glendoe headrace; Above: View of the dam

Glendoe bypassA bypass tunnel is to recover Glendoe’s headrace following a rockfall, writes Patrick Reynolds

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TUNNELLING

IN the last few years, four TBMs supplied by Italian manufac-turer and tunnelling subcontractor Seli were used to traverse varied, and often complex, geology in Ethiopia to construct tun-nels for two major hydro power schemes – Beles Multipurpose

(‘Beles II’) and Gilgel Gibe II. The projects called for a range of equip-ment, including one of the most advanced shields being used for weak ground, as anticipated at Beles II, but it was at Gilgel Gibe II that the most dif!cult challenges were faced when a double shield TBM unexpectedly encountered an extremely dif!cult fault zone.

Seli has worked on a number of hydro projects among the many sectors it has served over its 60 years of operations, which it celebrates this year. In Ethiopia, as often elsewhere, it was able to draw upon its experience as a tunnel subcontractor as well as innovative equipment provider to have its crews and engineers plan ahead and address the challenges to be faced, such as the known weak stretch of ground at Beles II, but also work to cope with and overcome unexpected dif-!culties when met, such as on Gilgel Gibe II.

The developer on each project is the Ethiopian Electric Power Corp (EEPCo), the main contractor was Salini Costruttori and the tunnel-ling subcontractor – and equipment supplier – was Seli.

BELES IILocated in Amhara region in north west Ethiopia, the Beles II scheme takes water from Lake Tana along a 12km long headrace tunnel to an underground powerhouse of 460MW (4 x 115MW, Francis units) installed capacity. The plant discharges to a 7.2km long tailrace which conveys the "ow to the river Jehana, a tributary of the Beles. The underground works on the project also include a 270m long penstock shaft and a 90m high surge shaft.

Beles II - HeadraceSeli selected a dual mode TBM to operate either as a double shield universal (DSU) or an earth pressure balance (EPB) machine to deal with the varied geology along the alignment of the headrace. The majority of the drive – approximately 10km – was in basalt up to UCS 350MPa with some local faults, but the 8.1m diameter TBM also had to bore through more than 1.8km of loose soils, described as lake deposits.

The cutterhead was equipped with 52 x 17” backloading and recessed discs for the hard rock drive, and switchover to EPB exca-vation mode took a few weeks to perform on the machine, one of Seli’s most advanced. The TBM, equipped to deal with squeezing ground and to undertake face treatment, cost about 15% more than a standard DSU TBM.

The tunnel is lined with 7.2m i.d concrete rings, each 1.5m long, formed of 300mm thick segmental concrete segments (6+key).

The TBM was launched in late 2006 and made reasonable progress, having bored about two-thirds of the tunnel after two years. Before then, and just after the midway point in the basalt drive, there was a large, blocky face collapse and recovery work called for polymer resins from Innotek to !ll the void and consolidate the rock mass, restoring the ground for the drive to continue.

By early 2009 the TBM had switched excavation mode and was driving through the lake deposits on the !nal stretch of its journey. Boring through the lake deposits, the EPB-DSU holed through in November last year.

Beles II - TailraceGeology along the tailrace was reasonably good basalt with some stretches of agglomerates and tuf!tes, and overburden was up to

The Beles II and Gilgel Gibe II projects have brought varied tunnelling challenges that were successfully overcome by TBM manufacturer and subcontractor Seli. By Patrick Reynolds

Meeting challenges in Ethiopia

Beles II – The TBM completing the headrace drive in Nov 2009


TUNNELLING

120m in areas, and 250m-370m elsewhere. About 17 major discon-tinuities, mostly vertical and obtuse to the alignment, were expected and would present locally poorer ground conditions.

Seli used an 8.07m diameter double shield TBM for the tailrace drive, which was bored from the outlet end of the tunnel towards the powerhouse. Like the headrace tunnel TBM, the tailrace machine’s cutterhead was equipped with 52 x 17” backloading and recessed discs. The cutterhead drive had a maximum torque of 5,250kNm, and the maximum design advance rate was 6m/h.

To test the ground ahead of the TBM, the machine is also !tted for probe drilling and 18 holes through which to extend the drills.

The tunnel lining for the tailrace was the same as for the head-race tunnel, and the annular gap !lled with 8mm-12mm peagravel and grout.

The TBM was launched in mid-2007 and completed its drive just less than a year later, in May 2008, and had advanced at an average of approximately 20m/day, achieving a best day of 36m (24 rings) and best week of 189m (126 rings).

Tunnelling operations on the tailrace were performed in 3 x 8hr shifts, 7 days per week with scheduled daily maintenance in the morn-ings, service extensions and probe drilling when required. In total, the ef!cient tunnelling system had 51.9% of the time in excavation and 23.4% in maintenance. Where there was time lost a prime reason was the blocking effect of the pea gravel from the quarry-derived, angular aggregate because no local "uvial sources of gravel were available.

With the headrace drive by far the more dif!cult compared to the tailrace on Beles II, the Seli tunnellers found the unexpectedly greater technical challenge came on Gilgel Gibe II, underway at the same time.

GILGEL GIBE IIGilgel Gibe II is a 428MW (4 x 107MW, Pelton units) scheme. The headrace tunnel is smaller diameter but, at 26km, is far longer than that of Beles II. Geology anticipated along the alignment included !ve main rocks – tertiary volcanics, rhyolite, trachyte, basalt and some dykes. As hard basalt was anticipated for the bores, the TBMs select-ed for the headrace drives were two 6.98m diameter DSUs that would bore from either end of the tunnel, on Inlet and Outlet drives.

The tunnel lining is 1.6m long concrete rings of 6.8m outside diameter and formed of four hexagonal, 250mm thick honeycomb segments.

In the end, the TBMs encountered 24 geological dif!culties, or clas-

si!ed, ‘events’, of varying scale and nature on the headrace excava-tions – 15 in the Inlet drive and nine in the Outlet drive. By far the most dif!cult to overcome was Event 19, on the Inlet drive.

Gilgel Gibe II – Inlet DriveThe drives started well and advanced 10m-20m per day despite the almost continuous presence of weaker rock and ravelling faces. Probes were drilled up to 50m ahead of the TBMs, From early on, though, it was the Inlet drive that was being more hampered by geo-logical problems – more than three times as many events to deal with even before Event 19 struck.

Chemical grouting was employed for local face stabilisation and some bypass digs were required to handle the early events. Overcutting helped to counter squeezing ground. The geological events caused hold-ups ranging from a few days to about a month. But when Event 19 occurred, in October 2006, about 14 months and just over 4km into the Inlet drive, it was to take more than 20 times as long to resolve.

The TBM had already stopped when the problem emerged that would be classi!ed as Event 19. There was a sudden extrusion and collapse of the face against the TBM, the progressive creep of the rock mass and crushing force against the shield bent and broke parts of the TBM, pushing it back more than 600mm and displaced it laterally by more than 400mm. Probing ahead, with some dif!culty, hot and high pressure mud was found – 40 degrees Centrigrade and up to 35 bar- 40 bar pressure.

Efforts were made !rst to open a small tunnel over the TBM to start to release the shield but high rock pressures prevented success. Next, a Back Chamber was to be opened up fully around the TBM and also an exploratory adit was excavated to the left from which boreholes would be drilled to probe the weak rock mass nearer the fault. However, the mud broke into the adit and overtopped bulk-head to reach and partly bury the TBM in the main tunnel. Two further surges of mud soon followed, and measurements showed they caused rapid reduction in acting pressure.

The tunnellers proceeded by opening up an adit to the right from which exploratory galleries were formed and much longer boreholes drilled to reach into and beyond the fault. A programme of drainage helped to lower the pressure in the rock mass around the TBM head and the partly constructed Back Chamber around the shield. The adit was then turned towards the front of the TBM to create space for the insitu recovery and repair work but could not continue due to loads and deformation rising, as a consequence, in the Back Chamber.

Eventually, without further excavation and the Back Chamber completed, the TBM could be fully accessed and was dismantled by early 2008. Removed to the surface, it was refurbished, rebuilt and re-assembled, and the cutterhead diameter was increased, to 7.07m, to help the TBM reduce the squeezing effects from rock mass with plastic behaviour. The shield was assembled again underground in a new chamber, located about 400m back from the site of Event 19. The intervening distance had been back!lled with concrete.

The TBM was relaunched in August 2008 on a bypass route around the fault, through which resin injection was used to help con-solidate the clayey basalt and to limit squeezing. Beyond the fault the TBM rejoined the headrace alignment.

The time and dif!culty in overcoming the problem of Event 19 meant that the Outlet drive did much more of the overall excava-tion than originally planned, and the Inlet drive would only bore the same distance again beyond the fault zone. The TBMs completed the headrace excavation in the middle of last year.

With the four TBM bores !nished on Beles II and Gilgel Gibe II, and the machines long gone, there is one remaining challenge at the latter project. Some months after the operations began at the hydro scheme a blockage was found in a short section of the headrace, on what was the Outlet drive. The investigations have revealed the cause to be a rock-fall at a zone of undetected, weak ground above and well behind the tunnel lining. It is believed the weak rock mass, comprising some loose large blocks in weak soil, was agitated by hydraulic pressure variations induced by the active headrace. Recovery work is well underway and the repairs to the tunnel should be completed soon. IWP& DC

Gilgel Gibe II – Breakthrough celebration at the headrace tunnel in mid-2009

22nd - 23rd September 2010 Innsbruck, Austria

DAM SAFETYSustainability in a Changing Environment

ATCOLD

Organized by

http://www.IECS2010.TUGraz.at

TOPICSpersonnel resources for design, construction, and operation of dams occurred in many European countries, leading to a decrease of skilled practiti-oners. In contrast to that, the construction of new dams undergoes a renaissance now, due to the de-mands of sustainable water and energy management, whereas the existing dams require increasing efforts for their maintenance and upgrading in order to sustain adequate safety and operability.

Therefore, strategic resource management beco-mes more and more important for the dam industry. One main aspect thereby is the transfer of valuable experience and knowledge from senior practitio-ners to their successors – an issue crucial for all parties involved: dam owners, designers, and contrac-tors, as well as authorities. Accordingly, sustainable management of knowledge transfer between the ge-nerations and between science and “day-to-day-busi-ness” will be one main scope of the symposium.

Day

1 21st September 2010Technical Excursion: Finstertal, ZillergruendlEvening: Meeting European Working Groups

SYM

POSI

UM

Day

2 22nd September 2010SypmposiumEvening Event

Day

3 23rd September 2010SymposiumEvening: Meeting European Club Board

Day

4 24th September 2010Technical Excursion: Finstertal, Zillergruendl

PROGRAMM

Sustainability of Know HowPublic Awareness of Dams and Dam SafetyMaintenance and RehabilitationRegulations and GuidelinesSmall DamsSurveillance Practice


TUNNELLING

THE Jinping I hydro power project is located in Sichuan Province in the Southwest of China, about 150km upstream of the Jinping II hydropower scheme (Wu and Huang, 2008). A 305m high arch dam – the highest of its type in

the world – has been developed as part of the project, with a total res-ervoir storage of 7.765Bm3 at a normal water level, and an adjustable storage of 4.91Bm3. The project construction began in November 2005, with the !rst generator planned to commence in 2013 and the whole project construction to be completed in 2015.

The power plant is designed to have a total installed capacity of 3600MW with a large underground powerhouse complex, consist-ing of headrace tunnels, a machine hall, bussbar tunnels, a trans-former chamber, two tailrace surge chambers and tailrace tunnels. The layout of the powerhouse complex is shown in Figure 1, with horizontal cover 110~300m and 180~350m vertical overburden. The underground powerhouse caverns are set in massive marble with faults and Lamprophyre veins crossing the caverns. The in-situ stress in the powerhouse region is high.

The powerhouse caverns include the machine hall (276.99m " 28.9m " 68.8m; length " width " height) with roof elevation at 1675.10m, the transformer chamber (197.10m " 19.3m " 32.7m) wall to wall distance of 45m downstream from the machine hall with roof elevation at 1679.20m, and surge chamber 1# (height of 80.5m, diameter of 41m and 38m upper and lower chamber, respec-tively), surge chamber 2# (height of 80.5m, diameter of 37m and 35m upper and lower chamber, respectively). The center to center distance between the two surge chambers is about 95.1m. A 3D illustration of the caverns is shown in Figure 2.

The machine hall and the transformer chamber longitudinal axes are parallel and oriented N65°W, with angles within 6.0°~ 36.5°, average of 16.3°, to the direction of the major principal stress, angle

of 45.0°~55.0° and 45.0°~60.0° to fault f13 and f14, respectively, and a small angle to NWW oriented joint set. The layout of the pow-erhouse complex is designed to be favorable to the stability of the surrounding rock masses. However, during the excavation, severe engineering problems were encountered such as cracks in shotcrete at downstream springlines both in the machine hall and the trans-former chamber. Large deformation in the rock masses in the vicinity of the faults and overstress of support elements were monitored. As a result, the excavation had to be paused in order to add additional

Shiyong Wu, Ziping Huang and Ge Wang present details on the engineering challenges and solutions developed during excavation of the underground powerhouse complex at Jinping I hydropower project in China

Excavation challenges and solutions at Jinping I

Above, left – Figure 1: Layout of the power-house and a horizontal geological profile at EL.1665; Right – Figure 2: 3D illustration of the underground power-house complex; Right, top – Figure 3: Topography above the powerhouse area, photo by Ziping Huang; Right, bottom – Figure 4: Three dominate faults intersecting the powerhouse


TUNNELLING

rock support to enhance the stability of the rock masses.

DESIGN OF THE UNDERGROUND POWERHOUSE

Engineering geologyYalong River flows towards N25 ºE at the dam site where the V shape deep valley is straight and narrow and the mountain is over 1000m high above the river. The base rock outcrops are shown in Figure 3. The rock formation in the powerhouse area is affected by tectonic movement with development of faults, shear zones and joint sets. The powerhouse complex is located in marble of Triassic,

with thin layers of greenschist. Lamprophyre veins invaded stretching straight over 1000m, with a width of about 2~3m, up to 7m, oriented N60~80°E/SE 70~80°, developing small faults in the vicinity of the veins. The body of veins is crushed with poten-tial instability problems. The bedding of the rock formation in the powerhouse is oriented N50~60°E/NW 30~40° dipping towards the valley. The faults f13, f14 and f18 are NE oriented, as shown in Figures 1 and 4 and are signi!cant to the stability of the rock masses. Fault f14 intersects the machine hall and the transformer chamber having a broken rock zone of 0.2~3m wide and an affected zone of 3~5m in each side of the fault. Locally the affected zone is about 20m wide, such as on the downstream wall of the machine hall at EL.1640 St. 0+103, where the rock masses are strongly weathered, as shown in Figure 5.

The major portion of rock masses in the powerhouse is classi!ed as III in Chinese rock mass classi!cation system with saturated uniax-ial compressive strength of 60~75MPa, deformation modulus of 6~15GPa. Fault zone and affected zone, lamprophyre zone, intensive joint zone are classi!ed as IV-V with saturated uniaxial compressive strength of 25~45MPa, deformation modulus of 0.4~3GPa. After excavation of Layer VI of the machine hall and the bussbar tunnels was completed, it was noted that the quality of revealed rock masses is in line with what assumed during the investigation. The in-situ stress is high in the area of the powerhouse. The major principal in-situ stress 1 is in a range between 20~30 MPa with a maximum of 35.7MPa, oriented N30~50°W/20~35°. Some borehole core discs are shown in Figure 6 taken during investigation. Other high stress induced rock phenomena include slabbing in the adit, buckling, etc. The measured rock strength to in-situ stress ratio is about 1.5~4. After excavation, large deformations of rock masses were record-ed and rupturing of rock masses, buckling of shotcrete, and large increase of load or stress in rockbolts and prestressed cable anchors took place.

STABILITY ANALYSIS OF POWERHOUSE CAVERNS AND ROCK SUPPORT DESIGN

Principle of rock support for the powerhouse caverns The major engineering geological challenges are the presence of three faults intersecting the underground powerhouse caverns and the fact that the rock mass strength is not very high. The following princi-ples of rock support of the powerhouse caverns are thus considered and implemented: Make use of rock masses to support themselves by applying "exible rock support approach, use systematic rock support with local enhanced support; implement dynamic support approach to adjust the rock support by systematic analysis combining excava-tion revealed rock conditions and the monitoring data with numerical back analysis of the rock deformation.

Stability analysis of the rock mass in the powerhouse The layout of the underground powerhouse caverns was designed to be favourable to the stability of the surrounding rock masses. One joint set, set No. 4 oriented N60~70°W/NE(SW) 80~90°, is nearly parallel to the walls of the machine hall and the transformer chamber and thus not favorable to the stability of the walls. The rock masses are generally stable with potential local instability. At locations with faults and the affected zones, the lamprophyre veins and intensive fractured zones the strength of the rock masses are low under the condition of high in-situ stress, and there is potential local instability of the rock masses featured by large deformations or rock failures.

Rock support design and the actual rock support The systematic rock support includes shotcrete, pattern rockbolts, and prestressed cable anchors. Additional rockbolts or cable anchors with smaller spacing and longer bolts, steel ribs, weak rock replace-ment with concrete and consolidation grouting were also applied to enhance the local stability, as shown in Figure 18.

In the machine hall roof, rock support includes a pattern rockbolts of 32, L=7.0m, prestressed rockbolts of 32, L=9.0m, prestressed to 120kN, spacing 1.2m #1.4m, wire mesh ( 8@20#20cm) shot-crete C30 and C25 20cm thick. For fault f14, above the springline at EL.1665.5m, longer rockbolts of L=9m, prestressed rockbolt of L=12m, spacing at 1.2#1.3m, and shotcrete steel rib were applied. The rib is 0.5m wide and spacing 1.2m~1.4m, containing two layers shotcrete C30 with each layer 20cm thick. Each shotcrete rib layer has main reinforcement rebar of 3 36@20cm, and distribution rebar

22@30cm.

ENGINEERING CHALLENGES AND SOLUTIONS Excavation progressThe machine hall is divided into 11 vertical layers for excavation. Excavation of an adit in the roof began in May 2005. In July 2009, excavation and rock support above Layer VI at EL1640m was com-pleted. Excavation and rock support of the transformer chamber commenced in May 2007 and was completed in November 2009. In July 2009, excavation of the two surge chambers reached Layer II at EL.1668m. Excavation and rock support of six bussbar tun-nels between the machine hall and the transformer chamber have been !nished.

Local instability of rock masses during excavationDuring excavation, rupturing (Figure 7), buckling, slabbing, slip-ping or shear along joints (Figure 8) in rock masses took place. Monitoring data indicated large displacements in extensometers and that stress or load exceeded the designed limit in some rock-bolts and prestressed cable anchors. At several locations cracks occurred in the shotcrete, steel ribs were bent by large deformation of the surrounding rock masses in the roof of the machine hall, as shown in Figure 9~10.

Figure 5 (a) Layer VI in the machine hall, St0+103, fault f14 wide around 0.8~3.5m, affected zone of 20m wide in the hanging wall of the fault; (b) Lamprophyre veins in the northern end wall of the machine hall


TUNNELLING

MONITORING DATA AND ANALYSIS Monitoring design and results Monitoring of rock masses deformation and rock supports stress is to ensure the safety of the construction and the operation, to provide effective tools to optimize the excavation and rock support design and excavation process. At nine cross sections intersecting the machine hall, the transformer chamber and the surge chambers, and the three faults, f13, f14, f18, extensometers rockbolt dynamometers and pre-stressed cable anchor dynamometers were installed (Figure 11).

Up to 4 May 2009, the number of measurement points with displace-ment less than 10mm is about 57.6% of the total points, the number of points with displacement between 10~50mm is about 31.9%, while the number of points with displacement greater than 50mm is about 10.5%. In about 72.8% of the total deformation measurement points the displacement is less than 30mm. The maximum roof vault settlement is recorded about 2.2mm, and the maximum displacement in the down-stream side rib of the roof 7.2mm. At St.0+031, St.0+126 and St.0+196, at EL.1659 and EL.1651, upstream side wall of the machine hall there are four points with displacement larger than 20mm. At St. 0+126, in the vicinity of fault f14 a displacement of 41.6mm was measured. In the downstream wall of the machine hall, there are 15 points with displace-ment larger than 20mm. There are seven points in the machine hall with displacement at rock surface larger than 50mm, with a maximum of 96.8mm. Among !ve points near the downstream springline there are two points in the vicinity of faults f14 and f18, three points related to joints of !ssures, the deformation developed within 0~9m deep (Figures 12 and 14). Another two points with displacement more than 50mm are at EL1650 and EL.1659, between Unit 3#~4#, in the downstream wall where the rock is integrated, the large deformation develops up to 12m deep in the rock mass. This is probably caused by high in-situ stress (Figures 13 and 15). Normally the deformation takes place within the !rst 5m in the rock masses.

In the transformer chamber the number of measurement points with displacement in three categories of less than 10mm, between 10~50mm and larger than 50mm at rock surface is about 33%, 48% and 19% of the total measurement points, respectively. The number of points with displacement less than 30mm is about 70% of the total measurement points. The chamber roof settlement is less than 5mm. Most measurement points in the upstream wall show displacement less than 12mm, large displacements up to 55.7mm were monitored between Unit 4#~6# at EL.1668. In the downstream wall at the same elevation, Unit 2#, 5# and 6#, displacement between 28.5~57.5mm with a maximum value of 132.7mm at Unit 5# were monitored. There are two and three points with displacement larger than 50mm at rock surface in the upstream and downstream walls, respectively.

In the upstream wall, the two points were located in integrated rock masses, large deformation develops down to 12m in the rock (Fig 16).

After excavation of Layer II in surge chambers 1# and 2# (EL.1688 to EL.1668), the doom settlement is about 0.1mm and 4.7mm, respectively. The maximum wall displacement in surge chambers 1# and 2# is about 11.5mm and 47.9mm both in the upstream wall at EL.1668, respectively, where the fault f18 and lamprophyre veins intersect the chambers.

Among 88 rockbolt dynamometers in the machine hall, with stress-es in ranges less than 100MPa, 100MPa~200MPa, 200MPa~300MPa and larger than 300MPa, the corresponding percentage of measure-ment points to the total points are 54.5%, 19.3%, 8% and 18.2%, respectively. There are six rockbolt dynamometers in the roof rib and springlines of the machine hall, and 10 in the walls exceeding the measurement limit (300MPa). The measurement points are within 2~6m deep in the rock.

There are 18 rockbolt dynamometers in the transformer cham-ber, with stresses in ranges less than 100MPa, 100MPa~200MPa, 200MPa~300MPa and larger than 300MPa, the corresponding per-centage of measurement points to the total points are 50%, 22.2%, 16.7% and 11.1%, respectively. The measurement points are within 2~4m deep in the rock.

In the surge chambers there are 18 rockbolt dynamometers, with stresses in ranges less than 100MPa, 100MPa~200MPa, 200MPa~300MPa and larger than 300MPa, the corresponding per-centage of points to the total measurement points are 44.4%, 16.7%, 22.2% and 16.7%, respectively.

There are 32 prestressed cable anchor dynamometers in the machine hall, among which about 76% dynamometers the measured load exceeding the locked value, 38.6% of the dynamometers exceed-ing the designed capacity, with a maximum exceeding load at St. 0+42.7, EL.1662.5, downstream wall. Of the 24 cable dynamometers in the transformer chamber, about 75% measured load exceeding the locked value, and 33% of the dynamometers exceed the designed capacity, at EL1664.5 (3) and EL.1661 (5) both in upstream and downstream walls of the transformer chamber. From the load devel-opment curve it is noted that the load tends to stable (Figure 17).

ANALYSIS ON THE LARGE DEFORMATION OF ROCK MASSES AND OVERSTRESS IN BOLTS AND CABLES

The large deformation of the surrounding rock masses in the caverns may be related to the engineering geological conditions and the exca-vation and rock support performance. The saturated uniaxial com-pressive strength of intact marble is not high while the in-situ stress is

signi!cant. The ratio of strength to stress is between 2~3.8, even as low as 1.7 locally. According to a Chinese Standard, in-situ stress in the powerhouse region belongs to high and extreme high locally. Observations made on the behavior of the rock masses during the excavation are in line with the descriptions of the rock under the same geological conditions in the Standard, including rock ruptur-ing, slabbing and fracturing. Therefore, large defor-mation in integrated rock masses may be expected.

In the vicinity of the faults f13, f14 and f18 in the machine hall and the transformer chamber, the quality of rock masses in the fault and the affected zones is poor. Even though there is no large rock block identi!ed from combination of faults and joints and !ssures. Geological investigations indi-cated that some combination of joint sets might be

Far left: Figure 6 Borehole core discs from the left bank indicating high in-situ stress; Left, bottom: Figure 7 (a) Rupturing of rock in the down-stream side rib of the machine hall at St.0+150 Left, top: Figure 8 Sliping along a joint indicated by shear movement of the blasting borehole on the upstream wall of the machine hall at St. 0+150m and EL1654–1650


TUNNELLING

unfavorable to the stability of high walls. Thus the geological struc-tures may also lead to large deformation of the surrounding rock masses.

The monitoring data shows that after excavation large deformation of rock masses develops relative shallow where the geological struc-tures presented while large deformation develops deeper in integrated rock masses with higher in-situ stress.

Obviously the large deformation in rock masses caused the over-stress in bolts and prestressed cable anchors. It may be necessary to analyze a proper support pressure that allows certain deformation of the rock masses while the stress or load built up in the bolts and prestressed cable anchors is limited to a certain extent.

MEASURES TO CONTROL THE LARGE DEFORMATION OF THE ROCK MASSES

Rock support measures are requested to limit the shallow deforma-tion in the rock masses by reinforcing the loosened rock masses and thus prevent it developing further inside the rock, creating a rein-forced deformable rock ring to support rock inside and thus ensure the overall stability of the surrounding rock masses.

To control the large deformation in the vicinity of faults in the roof where large displacements were monitored, rock support measures include systematic rockbolts, shotcrete, double layers rebar reinforced shotcrete rib, systematic prestressed cable anchors, and fault anchors. Figure 11 shows the concrete beam and prestressed cable anchors in the downstream side, at springline and upper wall of the machine hall. The monitoring data indicates that the displacements of the rock and stress of the rockbolts and cable dynamometers tend to be stable after the installation of the extra rock support.

At locations with large deformation in the walls of both the machine hall and the transformer chamber, the loosened rock blocks were removed and heavy rock support was applied such as steel !bre shotcrete, random rockbolts, prestressed rockbolts, pre-stressed cable anchors. At some locations when the displacement did not converge prestressed, so many cable anchors were installed that there was no room to install any more, see Figure 18. Finally, the rock masses are stable.

DISCUSSIONAfter excavation of Layer IV in the machine hall, due to large defor-mations, the excavation of the machine hall had been paused for about half a year in order to apply extra rock supports. An option to avoid large deformation of walls could be that the high wall was designed as an arch shape rather than a straight line. There might be less deformation due to smaller loosened zone in the shallow region and thus probably such heavy rock support might be not requested. Much smaller displacements in the roofs of the caverns provide some evidence on the design alternatives of the wall. Numerical modelling could have been applied to simulate this option. Economical evalua-tion should be carried out to compare the options on cost and exca-vation progress. For the long term stability of the surrounding rock masses the arch shape walls may be favorable.

Delay of the rock support after excavation may have partly contrib-uted the large deformation. After blasting, if the rock support was not installed in time, the joint may open and blasting induced !ssures may further develop and cause larger loosening zone. This is against the prin-ciple of NATM to make use of the reinforced rock ring to support the surrounding rock masses themselves. And thus large deformation took place, with high stress built up in rockbolts and cable anchors.

With regard to rock bolting, under the conditions of low strength stress ratio large deformation of the rock masses may be expected, end anchored rockbolt combining grouting should have been consid-ered, such as CT-bolt widely used in Norway, where full grouting of the bolt is applied later. The cable anchors were probably prestressed too much to stand for further support pressure due to further defor-mation development. Therefore so many prestressed cable anchors were overstressed beyond the designed capacity. The support was probably too stiff to accommodate future displacement of the rock masses. Numerical modeling and analytic study may be useful to study a proper prestress load level and timing of installation of the cable anchors combining a study on an acceptable and reasonable displacement magnitude of the rock masses in caverns.

CONCLUSIONS

The geological challenges of the Jinping I hydro power project under-ground powerhouse are the presence of faults and lamprophyre veins intersecting the caverns, high in-situ stress in the region, integrated marble and thus low strength to stress ratio. During excavation large deformations of the rock masses occurred, high stresses built up in some rockbolts and prestressed cable anchors in the machine hall and the transformer chamber. The monitoring data shows that large deformation of rock masses develops relative shallow where the geo-logical structures presented while it develops deeper in integrated rock masses where the high in-situ stress plays important role.

The stability of the caverns was under concern and the excava-tion was paused for months in order to apply extra rock supports to enhance the reinforcement of the roof and the walls of the caverns. The additional rock supports were heavy and effective. At present the monitoring data indicate that the displacement in rock masses and stresses in rock supports are stable. Observations also con!rm that the surrounding rock masses are stable overall.

The additional rock supports were costly and impacted the con-struction progress considerably. What we could learn from the excavation and the design may be meaningful. Given that a large deformation of the surrounding rock masses is expected, a design of arch shape walls rather than straight high walls may lead to smaller displacement of the walls and reduced amount of rock support, even though the excavation work may increase. Prestress level and timing of installation of the cable anchors could have been optimized in order to save cost and to increase the reliability of the rock support elements, and secure the long-term safety of the support and stabil-ity of the powerhouse caverns during operation. Rock support of end anchored rockbolts and shotcrete installed in time is critically

Left top and bottom: Figure 9 (a) Spalling of shotcrete at St. 0+170 down-stream rib of the machine hall roof; (b) Spalling of shotcrete in detail; Left, small image: Figure 10 Bending of the reinforced shotcrete rib in the roof


TUNNELLING

important in forming a reinforced rock ring to ensure the rock masses support themselves, and thus prevent loosen zones deteriorating further into rock masses.

For further information, please contact the authors via email: [email protected]

Above: Figure 18 – Enhanced rock support in the downstream side roof, springline and upper wall of the machine hall, photo by Ziping Huang

IWP& DC

ReferencesWu, S. and Huang, Z. 2008. Tunnel vision at Jinping. International Water Power & Dam Construction. September 2008. Pp17-18.

CHIDI 05.2009, Stability analysis and rock support review report on the surrounding rock masses of Jinping I hydropower project underground powerhouse caverns.

CHIDI 09.2003 Feasibility study of Jinping I hydropower project.

Left: Figure 11 – Layout of the monitoring cross sections, 1-1~9-9 in the powerhouse complex, with the location of faults; Above: Figure 12 – Displacement distribution in extensometers at Cross Section 4-4, in the machine hall and the transformer chamber; Below: Figure 13 – Displacement distribution in extensometers at horizontal profile at EL.1666, in the machine hall, transformer chamber and surge chambers; Left, below: Figure 14 – Displacement curve with M6ZCF-Z3 at St.0+95.10 downstream wall of the machine hall, in the vicinity of fault f14; Bottom, left: Figure 15 – Displacement curve with M4ZCF3-5 at St.0+79.20 downstream wall of the machine hall at EL.1650, inte-grated rock mass; Bottom, middle: Figure 16 – Displacement curve with M4PS2-8 at St.0+126.8 downstream wall of the transformer chamber at EL.1668, integrated rock mass in the vicinity of fault f18; Bottom, right: Figure 17 – Load vs. time of a cable dynamometer at EL1661, downstream wall of the transformer chamber


NEW TECHNOLOGY

NEW from Atlas Copco is the QAS 500 generating set which offers dual frequency operation rated at 500kVA at 50Hz (571kVA at 60Hz). It also has noise reduction and envi-ronmental protection features for continuous on-site power

in industrial, public utilities and construction applications. The QAS range, comprising a wide variety of models rated between

14–571kVA has been designed for fast, easy and safe transportation and on-site handling on virtually any unprepared surface.

Housed in a noise attenuated enclosure made from zinc plated steel and painted with powder coating paint, the QAS 500 meets a sound power level (LWA) of 99 dB(A) at 50Hz; making it suitable for appli-cations in noise sensitive areas. The enclosure also provides optimum resistance against corrosion ensuring that it remains in good condi-tion and retains an improved resale value, says the company.

An integrated lifting structure on the enclosure has been designed to contribute to the total sturdiness of the set to ensure safe and ef!-cient handling. It is positioned in the centre point of gravity for cor-rect balancing and is dimensioned to support at least four times the maximum weight without breaking.

The integration of forklift slots also saves time and facilitates safe and ef!cient handling and transportation. Well placed !xation points ensure safe transportation around the construction site, while integrated bumpers protect the enclosure against mechanical impact during transportation and handling.

The frame is also a 110% containment base for all the necessary liquids such as oil, coolant and fuel.

EASE OF MAINTENANCE Large access doors allow easy access to all service points and the gen-erator components; developed to make any preventative maintenance and repairs faster and easier.

External drain points are positioned to allow easy and ef!cient draining of oil, coolant and fuel with minimised risk of environmental spillage. Special drain points are also !tted to allow the fuel tank to be cleaned and water removed from the base frame; once again with minimal environmental impact.

A 905 litre standard fuel tank, positioned in the centre of the base frame ensures continuous operation at full load for a complete shift.

The new QAS 500 features a dedicated compartment for the electrical cubicle making it safe to access even when ‘running.’ Isolating the electri-cal components from the engine compartment provides reduced vibration and temperature impact on the more sensitive electrical components.

An industrial type B-curve, four-pole main circuit breaker safeguards the alternator against external short circuits by an instantaneous trip three to !ve times the nominal current. All main circuit breakers !tted in the QAS range are Omnipolar – an essential feature for compatibility with the different con!gurations of customers’ applications.

FAIL SAFE PROTECTION Critical engine parameters such as oil temperature, oil pressure and coolant temperature are monitored by means of a failsafe system.

Should a sensor or transducer fail, the system automatically shuts down to avoid any damage to the engine.

A dual stage fuel !lter with integrated water separator and a heavy duty dual stage air !ltration system ensure longer service intervals and increased engine life and up-time. An extra safety cartridge !lter element allows air !lter replacement during operation.

Generator control, protection and monitoring are provided with a local or remote start digital control module (Qc1002). Fitted as stand-ard, the system is ideal for all automatic controlled applications. All Qc controllers are equipped with external communication protocols prepared to support the Cosmos option for satellite monitoring.

The Qc4002 controller is available as an option for multi start paralleling operations. As a standard, this controller is equipped with PMS (Power Management system), that enables the user to save fuel and to extend the life time of the engine.

FULFILLING DEMANDS

To ful!l the demand in the market for 800kVA, Atlas Copco has upgraded its QAC 750 to the QAC 800.

The new QAC 800 delivers 800kVA of prime power at 50Hz to meet increasing demands from generator users in the market. The QAC series generators are built to withstand the most extreme temperatures, and are designed to work in all weather conditions. A built-in engine coolant heater ensures quick and easy start-up in cold conditions, while a variable speed electric cooling fan allows continuous operation in higher temperature environments, as in desert environments.

Designed with safety in mind, all QAC series generators have a four-pole main motorised circuit breaker, providing overload and short circuit protection, an emergency stop, automatic engine alarms and shut-downs.

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The state-of-the-art Atlas Copco Qc 4002 control panel includes features such as an LCD screen with numerous read-outs, warn-ings and shutdowns – all displayed in various local languages. Applications from ‘Island operation’ and ‘Automatic Mains Failure’ to the most complicated paralleling operations such as ‘Load shar-ing,’ and ‘Base load’ operations, are done with this single, high-tech generator controller.

This multi-purpose control system makes the QAC series genera-tor an easy-to-operate machine, offering a single solution to varying applications, says the company. IWP& DC

IWP&DC looks at Atlas Copco’s latest developments in generation technology

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Carpi_July10:Carpi ad Oct07 28/7/10 08:49 Page 1


GENERATORS

THE energy and micro-generator manager (EMMA) is a device that is installed alongside a micro-generator for hydro, PV or wind. It monitors in real-time what your micro-generator is producing and what energy you are

using in small commercial buildings or households. If it detects there is surplus electricity available it then diverts this to an immer-sion heater for the production of hot water or similar resistive load device. This energy can then be stored and used when required.

The EMMA is bene!cial as between 45%, and in some cases 80%, of what you generate is exported to the grid because of the miss-match between the electricity generation and the demand pro!les. EMMA matches these two curves. Up to 40% of household energy requirements are for hot water and so the excess electricity is usually put to good use satisfying this requirement. Over 60 devices have been installed across Ireland and the UK.

THE YOUNG EMMAEMMA was developed over two and a half years ago in Ireland where there was no export tariff for any electricity put into the grid from a micro-generator. Prior to development we had searched worldwide to try and !nd a similar technology, but as none was found we decided to develop it ourselves.

The unique technical feature of the EMMA is that it seamlessly ramps the electricity up and down to the immersion heater (or similar resistive load device) using patented control technology. This may seem a simple solution but it has taken many thousands of hours of development time. In some countries the technology is !nancially very attractive. For example, in the UK you only get 3 pence per kWh exported and so it makes sense to use the electricity in the house

rather than re-import it later. You receive the feed-in tariff based on what you generate, not what you export. This is not impacted by installing EMMA.

There are a variety of uses for EMMA, which include:

In any country where the export tariff for electricity is low or zero.Any house/small commercial/school with more than 1kW micro-generator with immersion/ hot water tank. Install with micro hydro, PV or micro wind.Where client wants a micro-generator and a thermal solar system. Put EMMA instead of thermal solar at 30% of the costs.Where hot water is produced from electricity/gas/oil central heating and uses a hot water cylinder.Up to 30kW (larger units are bespoke).Grid connected - three phase or single phase.

The main bene!ts of using EMMA technology are that you can sig-ni!cantly increase the rate of return on investment in your micro-generator; help stabilise the distribution network; and further reduce reliance on fossil fuels.

Figure 1 shows actual data from a site where an EMMA is installed. There is a signi!cant miss-match between the demand and generator output pro!les. This is typical of most sites where we have installed EMMA and have been able to monitor this data.

Figure 2 shows the same site with the EMMA switched on. Here the pro!les are matched perfectly within the operating constraints of the generator. There are some times where the overall demand is higher than the output from the generator. In this case the EMMA ramps the immersion to zero and some electricity will be imported to the household.

Generating interest in EMMARichard Linger from CoolPower Products in Ireland introduces IWP&DC to EMMA: an energy and micro generator manager which is being used to optimise the performance of a 90-year-old water turbine in the UK

Restored controls at a micro hydro site in Andover Drive mechanism at the Andover hydro site


GENERATORS

Effectively the energy produced from the micro-generator is priori-tised. First use is always allocated to the household. Secondly to the hot water production, if required, and thirdly to export to the grid. This ensures the most effective payback for the user.

The EMMA can be used with other technologies and has been connected to storage heaters and electric under!oor heating systems. It comes in a standard range of sizes from 4kW single phase up to 30kW three-phase phase systems. We can do larger devices but these would be bespoke designs.

MICRO HYDRO INSTALLATION

We recently installed an EMMA with a 3.7kW micro-hydro genera-tor in Andover, Hampshire, UK. This project has been a great success. The client restored a 90-year-old turbine which had remained idle for many years. On this site the client installed two heat storage systems, one for his domestic hot water and the second for the central heating. When there is excess electricity available it is put into the domestic hot water cylinder "rst, when this is full it then starts to heat the cen-tral heating cylinder. The EMMA paid for itself in a matter of months as the client was no longer using his large oil-"red boiler to heat his domestic hot water.

We are planning to install EMMA in a number of other micro-hydro projects in the UK over the next 12 months. Most of these are in remote areas where the EMMA can help further displace fossil fuels and increase the rate of return on the micro hydro investment.

A recent development of the product is the grid voltage stabilisation version (GVS) which we are trialling with UK network operators. The EMMA GVS allows you to connect larger micro-generators to the grid in areas where the network operator is imposing limits.

The EMMA GVS monitors the network voltage and the export capacity. It can react by limiting export levels when the voltage is higher than a speci"ed point or simply limit the export capacity. The bene"ts are that you do not have to pay for a costly network upgrade and can install a larger micro-generator to match your requirements. You also get all the bene"ts of the EMMA in terms of usage of energy on-site, and reduced imports/costs.

The EMMA GVS can also be used where you have a high concen-tration of micro-generators in an area. Here the bene"ts are a stable network and optimised use of the electricity being generated. There are projects underway in the US trying to determine a solution for this type of problem. EMMA GVS offers a solution.

The future offers exciting opportunities for EMMA technology. For example, we are scoping an opportunity to pilot the use of EMMA in demand side management/smart grids. As you are able to control devices in response to signals sent to the EMMA, or in response to voltage peaks or troughs, it can therefore be used to reduce the cost of electricity supply or stabilise grid networks.

Richard Linger, Director Coolpower Products Ltd, 89 Booterstown Ave, Blackrock, Co. Dublin. Ireland

Email: [email protected] www.Coolpowerproducts.com

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01:05:00

07:10:00

13:15:00

19:20:00

01:25:00

07:30:00

13:35:00

19:40:00

01:45:00

07:50:00

13:55:00

20:00:00

02:05:00

08:10:00

Demand

Output

IWP& DC

Top left: Figure 1 – Site where an EMMA is installed; Top right: Figure 2 – the same site with EMMA switched on; Left: EMMA in stainless steel housing; Right: Mill race and sluice gate at a micro hydro site in Andover, Hampshire, UK


MODELLING

IN March 2009 Dave Holt, hydro project leader of the Goring & Streatley Sustainability Group (GSSG) wrote the article ‘Power to the people’ for IWP&DC. This gave readers an insight into the innovative hydro scheme that is planned for

the River Thames at Goring and Streatley in the UK. The scheme comprises of three Archimedes screws driven by the

head difference of the Goring weir complex resulting in an estimat-ed 246KW peak output. This renewable energy will be sold to the National Grid to generate an income that will fund other local sus-tainable projects in the area.

Since March 2009 Dave Holt and the GSSG have progressed with the project and commissioned Peter Brett Associates (PBA) to assess the !ood risk associated with the scheme. Flood risk is an inherent issue with such an installation and needs to be evaluated and miti-gated against accordingly. The evaluation of the !ood risk therefore lends itself to a comparative exercise comparing the current or base line !ood risk against the !ood risk with the proposed design in place.

This is best evaluated by quantifying !ood levels for both scenarios with a solution showing no difference between the two.

Through close liaison with the Environment Agency, PBA agreed a methodology to assess the scheme using the powerful tool of hydrau-lic river modelling.

GORING AND STREATLEY WEIR

Historically, water levels within the non-tidal section of the River Thames have been heavily modi"ed and managed through the con-struction of weirs and locks for navigation and for powering numer-ous mills for industry.

These weir complexes are still used today for managing water levels for navigation and also for managing the !ood risk to the towns and villages that have expanded into the Thames !oodplain.

Typically a weir complex consists of "xed crest weirs with addi-tional sluice or radial gates to manage water levels during times of

James Heptonstall from Peter Brett Associates provides an insight into the methodology used for !ood risk modelling on the River Thames in the UK

Assessing flood risks for Goring and Streatley hydro

View west towards Goring and Streatley Weir


MODELLING

high or low !ows.The Goring and Streatley weir complex consists of two separate

areas divided by Withy Eyot. On the western (Streatley) side, the weir complex incorporates a mill channel, two gated weirs, a Paddle and Rymer weir, and a series of over!ow weirs. On the eastern (Goring) side, the weir complex consists of three gated weirs, a series of over-!ow weirs, a lock island, a lock and a mill channel.

The proposed hydro power scheme is to be situated on the 16m long over!ow weir adjacent to the lock keeper’s house on the Goring side of the Thames. The screws would effectively obstruct 13m of weir from the Goring and Streatley weir complex.

FLOOD RISK ASSESSMENT

English government Planning Policy Statement 25 (PPS25) requires that new development does not create an increase in !ood risk to third parties.

The complexity of the Goring and Streatley weir complex and !ood hydraulics of the Thames along this reach required a hydraulic modelling approach to satisfy the requirements of PPS25.

The Environment Agency, as regulators, worked closely with the GSSG to produce a modelling speci"cation that utilised their existing strategic !ood risk mapping ISIS (1 Dimensional) hydraulic model.

Using this model, PBA were commissioned by the GSSG to "rst provide a review of the existing hydrology and hydraulics of this ‘baseline’ model to assess the suitability of the model for assessing !ood risk at Goring.

Secondly PBA were requested to produce a design model that included the three Archimedes screws, associated housing and con-trol building. Each model would be run for three increasingly greater magnitude !ood events (1:5 year (222m3/sec), 1:20 year (284m3/sec) and 1:100 year (355m3/sec). The predicted increase in !ows over the lifetime of the development from climate change was also accounted for by increasing the 1:100 year !ow by 20%.

A comparative exercise would be then carried out to assess how the hydro power scheme impacted on !ows across the weir system and how this might impact on !ood risk to third parties.

STAGE 1: MODEL REVIEW

The Environment Agency Strategic ISIS hydraulic model covers the area between Sandford on Thames, 32km upstream of Goring, and Whitchurch on Thames, 8km downstream of Goring.

The model represents the channel and floodplain using either extended cross-sections or via a quasi two-dimensional approach using lateral spills into reservoir units that represents large !ood stor-age areas within the Thames !oodplain.

The strategic nature of the model meant that in rural areas,

where the channel and !oodplain are uniform, model detail was low with cross-sections spaced anywhere up to 700m apart. However around the weir complexes such as at Goring and Streatley, the model schematisation was found to be detailed and provided a good representation of the weir hydraulics and there-fore was suitable for the !ood study.

The hydrology for the model was originally based on the Dunsmore technique that estimates design !ows from a !ow-catch-ment area relationship that can be derived from the long gauging records on the Thames. The method was originally derived in 1991. For this project PBA reviewed the results from the method using the additional 17 years of extra !ow gaugings made available by the Environment Agency, which had been recorded on the Thames gauge network since the method was derived. The method was found to still provide a reliable estimate of design !ows and so the hydrology was left unchanged.

STAGE 2: HYDRO POWER MODELLING

The main components of the scheme include three, 3.6m diameter Archimedes screw turbines, a control building and an additional gated weir for mitigation.

The control building is to be designed to !ood with any sensitive plant set above the 1:100 year !ood level including an allowance for climate change and freeboard. The building itself will be small enough not to impact on !ood !ows.

The three turbines are expected to occupy a 13m section of the 16m wide "xed crest weir adjacent to the lock house. The additional gated weir is then proposed to occupy the remaining 3m of the "xed crest weir.

A conservative assumption was made that the three turbines would create a complete blockage over 13m of the existing "xed crest weir. This section of the weir was therefore removed from the model.

Initial analysis of the model showed that the turbines had greatest impact at low return period !ood events, redistributing !ow across the other structures. The results also showed that the weir rapidly became drowned out with increasing !ows, caused by backing up from a downstream railway embankment and bridge. As the weir became drowned out, the impact from the turbines reduced to dis-placing less than 4% of the total !ow in the river, causing no change in !ood level.

Due to the sensitivity of some property in Goring and Streatley to relatively frequent !ood events, it was important that mitigation was provided at the low return period events (1:5yr to 1:20yr design events) to ensure no increase in !ood risk to these receptors.

A gated weir was therefore proposed and modelled with a lower "xed crest than the existing weir. This effectively allowed an increase in !ow across the structure at the lower return period !ood events, fully mitigating for the hydropower scheme.

STAGE 3: APPROVAL

A !ood risk assessment has been written based on the modelling results and submitted to the Environment Agency, alongside the hydraulic model for approval. The project has been run in close liai-son between the Environment Agency, GSSG and PBA which has thus far proved effective in moving the project forward in a consistent direction. It is expected that this will continue with planning permis-sion being sought later this year.

James Heptonstall, Assistant Hydrologist, Peter Brett Associates, Caverhsham Bridge House, Waterman Place,

reading, Berkshire RG1 8DN, UK. Email: [email protected]

www.peterbrett.com

IWP& DC

Schematic of an Archimedes screws (Ritz-Atro)


SEDIMENTATION

LARGE dams have been constructed worldwide at a rate of 1.2 dams/day since 1930, based on the dams registered on the ICOLD World Register of Dams. Many of these struc-tures will continue to !ll up with sediment as they age.

High rates of sedimentation in many reservoirs and better care of long term sustainability have emphasised the importance of reser-voir sedimentation. The main problems which can be encountered include: loss of storage; damages to turbines and loss of hydropower production; and downstream impacts.

The total world reservoirs storage is about 7000km3 (6100km3 based on the ICOLD Register of Dams, but if smaller <15m dams are included, 7000km3 could be the current total storage). About 3000km3 of this is dead storage for hydropower. Of 4000km3 of live storage, most of this is devoted to hydropower and about 1000km3 to irrigation dams, potable or industrial water storage; part of which is in multipurpose dams.

The annual sediment load of the world’s rivers together is estimated to be between 24-30B tons for a water in"ow of 40,000km3, ie an average sediment content of 0.6-0.75T/1000m3 of water but it varies

enormously according to the river and to the discharge. All rivers are not dammed and all sediments are not trapped in reservoirs: the accumulated sediment storage in world reservoirs has been evaluated as 1400Mm3 for 30 to 40-year-old dams on average, ie in the range of 40Bm3 per year, ie 0.6 % of the total storage per year.

The historical growth in storage capacity up to 2010 based on the ICOLD World Register on Dams, and historical and predicted reservoir sedimentation is shown in Figure 1.

Most sedimentation is at hydropower dams, partly in dead stor-age but the loss of power supply is however not proportional to the loss of live storage. The annual loss of power supply appears in the range of 0.5% of a total investment of about US$1000B for live storage, ie US$5B per year. As hydropower reservoirs silt up however, they have to be replaced by new dams eventually at a cost of the total storage capacity (dead and live) and at a total investment of US$1700B, the annual cost of replacement is 0.6% x 1700 = US$10B/year.

The annual loss of storage of irrigation reservoirs, possibly 7Bm3, impacts directly on the irrigation capacity; for an investment of

Worldwide experts will convene in South Africa in September 2010. At the top of their agenda is the growing problem of river sedimentation. Professor Gerrit Basson explains why tackling this issue is of great importance to the dams industry

Tackling agrowing problem

US$0.2-0.5/m3 for reservoirs in excess of 10Mm3, or up to US$1/m3 for dams smaller than 50000m3 (often found in the Indian sub continent and in Africa), with say a global investment cost of US$0.5/m3 the annual loss may be in the range of US$3.5B. There is also the cost of downstream damages and, for possibly 5 or 10% of hydro-power plants, losses of power supply and cost of maintenance for turbine wear.

The total yearly loss linked with sedimentation problems is thus about US$15B (excluding downstream impacts) and with downstream impacts considered the annual cost is about US$17B. This should how-ever be compared with the annual overall costs and bene!ts of dams:

Some US$40B of investments and US$17B for operation, main-tenance and upgrading (0.7% x US$2400B; rate usually 0.3 to 0.7%), ie a total cost in the range of US$57B. Some US$125B of electric power supply (2500 TWH x US$0.05) and other bene!ts (especially food by irrigation for over 500 mil-lion people).

The total yearly impact of siltation of US$17B should thus be com-pared with the overall yearly costs (US$57B) and overall yearly bene!ts (US$175-225B) of world dams. The annual cost of reservoir sedimen-tation (in terms of replacement cost) is about 30% of the overall costs which is not insigni!cant. However, much less than 30% is currently spent on sedimentation mitigation measures and the problems are therefore postponed to future generations in many countries.

POTENTIAL IMPACTS OF STORAGE CAPACITY Based on the ICOLD World Register on Dams, hydropower dams make up 81.5% of the world’s total current storage capacity. In 2006, 35% of the total storage capacity for hydropower had been !lled with sediment. By 2050 this predicted proportion of current total capacity that would be !lled with sediment has risen to 70%.

For dams for any other purpose (non-hydro), in 2006, 33% of the available capacity was !lled with sediment, rising to a predicted value of 62% by 2050.

It is expected that non-hydro dams will be severely impacted on when they reach a 70% sedimentation level. At this sedimentation level there will be about a 40-50% water yield reduction, and there could be problems at the intakes. Based on the global data this will occur by the year 2065, and will occur per region as indicated in the table (p40).

Hydropower dams can generally be !lled with sediment to a higher level than non-hydropower dams, as it is mainly necessary to main-tain the head for the power generation, and a storage capacity suf-!cient to meet all expected demands for power. It is expected that hydropower dams will be severely impacted when they reach a level of sedimentation of 80%. Based on the global data this will occur by the year 2070, and per region as indicated in the table.

Countries that are anticipated to have critical sedimentation volumes by year 2050 are: Afghanistan, Albania, Algeria, Bolivia, Botswana, China, Columbia, Ecuador, France, Fiji, Iran, Iraq, Jamaica, Kenya, Libya, Malaysia, F.Y.R.O. Macedonia, Morocco, Mexico, Namibia,


SEDIMENTATION

Time (years)1980 1990 2000 20101940 1950 1960 1970

South AmericaNorth AmericaMiddle EastEuropeCentral AmericaAustralasiaAsiaAfrica

7000000

6000000

5000000

4000000

3000000

2000000

1000000

0

Gro

ss s

tora

ge c

apac

ity (m

illio

n m

3 )

Opposite page: Sedimentation at a dam in Algeria Left: Abstraction works to limit sediment in the Berg River Above: Figure 1a: Historical growth in global storage capacity; Figure 1b: Historical growth in global reservoir sedimentation (Basson, 2010)

South America lossNorth America lossMiddle East lossEurope lossCentral America lossAustralasia lossAsia lossAfrica loss

4500000

4000000

3500000

3000000

2500000

2000000

1500000

1000000

500000

0

Sedi

men

t vol

ume

(mill

ion

m3 )

Time (years)1980 1990 2000 2010 2020 2030 2040 20501940 1950 1960 1970


SEDIMENTATION

New Zealand, Oman, Pakistan, Puerto Rico, Saudi Arabia, Singapore, Sri Lanka, Sudan, Tanzania, Tunisia and Uzbekistan.

SYMPOSIUM ON SEDIMENTATION

In order to help countries tackle the problems associated with sedi-mentation, the 11th International Symposium on River Sedimentation (ISRS) will be held in South Africa from 6-9 September 2010. The ISRS is held to bring together scientists and engineers working in the !elds of river, lake and reservoir sedimentation, and covers theo-retical and practical aspects related to sediment transport processes, including environmental aspects. The impacts of hydraulic structures on "uvial morphology as well as measures to limit the impacts for sustainable development of water resources are also key elements. Other noteworthy areas include a focus on catchment soil erosion programmes, sediment monitoring techniques, reservoir "ushing and other techniques to limit sedimentation, environmental aspects including water reserve determination for river ecology.

Keynote presentation topics include:

Mega deltas and the climate change challenges by Dr Kim Wium Olesen, Head of Water Resources Department, DHI. Sediment Data Collection in Rivers, Reservoirs and Lakes by Prof. Dr. Manfred Sprea!co, University of Berne, Switzerland. Erosion and Sedimentation Research Emphasis in the USA by Dr. Matt Römkens, United States Department of Agriculture (USDA) Agricultural Research Service (ARS). An introduction to latest developments in soil erosion and sedi-ment transport modelling by Dr. Weiming Wu, National Center for Computational Hydroscience and Engineering (NCCHE), The University of Mississippi, USA.

New challenges in sedimentation and erosion research by Professor Zhao-Yin Wang, Tsinghua University, China.

The four-day symposium also includes a technical visit to the recently completed Berg River dam, the !rst in South Africa where environ-mental "oods are released for ecology, in addition to erosion protec-tion works at Cape Town.

Professor Gerrit Basson, Director of the Institute for Water and Environmental Engineering; Department

of Civil Engineering; University of Stellenbosch, South Africa. He is Chairman of the ICOLD Sedimentation

Committee (2004 to 2010). He can be contacted directly about the conference at [email protected]

IWP& DC

Growth hydroLoss hydroGrowth otherLoss other

6000000

5000000

4000000

3000000

2000000

1000000

0

Stor

age

capa

city

(mcm

)

1900 1920 1940 1960 1980 2000 2020 2040Year

ReferencesBasson (2010). ICOLD Bulletin: Sedimentation and Sustainable use of reservoirs and river systems. ICOLD Sedimentation Committee. Editor.

Year that current storage will reach critical sedimentation levelsRegion Hydropower dams:

Date 80% filled with sediment

Non-hydropower dams: Date 70% filled with sediment

Africa 2100 2090

Asia 2035 2025

Australasia 2070 2080

Central America 2060 2040

Europe and Russia 2080 2060

Middle East 2060 2030

North America 2060 2070

South America 2080 2060

Above: Testing of environmental flood releases at Berg River Dam Right: Figure 2 – Global comparison of growth of dams by purpose

SymposiumThe 11th International Symposium on River Sedimentation (SRS) is organised by the University of Stellenbosch, near Cape Town. The ISRS is held every three years with the World Association on Sedimentation and Erosion Research (WASER) as the main sponsor. Others include: the International Research and Training Centre on Erosion and Sedimentation (IRTCES), UNESCO, ICOLD and the South African Water Research Commission (WRC).

The main theme is sedimentation and the sustainable use of river systems. Papers were also invited under the following themes:

Reservoir/lake sedimentation modelling and management.Sediment data collection in rivers, reservoirs and lakes.Dam break analysis and sediment transport.Reservoir sedimentation and management, such as !ushing or dredging.Sustainable tailings dams.Unlined dam spillway scour.Hydraulics and environmental aspects of river sediment transport processes (fundamental and modelling).Fluvial morphological and environmental impacts of hydraulic structures on the downstream river and possible mitigation measures.Impacts of river sedimentation on hydraulic structures (diversion, abstraction works, bridges, etc.).Sediment yield, soil erosion determination, modelling and management.Climate change impacts on sediment yields, river and estuary morphology

More than 250 delegates are expected to attend the symposium in September. Note that the deadline for registration is 31 July 2010. Full details can be found at: www.civeng.sun.ac.za/isrs


SEDIMENTATION

AN environmentally-friendly dewatering system is being launched after a successful pilot project which helped to keep Britain’s canal network open to traf!c. The Sedi-!lter system has been created as a complete solution to

dewatering engineering projects. Designed by environmental waste management !rm Aardvark EM, the system is manufactured by DRM Industrial Fabrics, which specialises in performance !ltra-tion through design. Its creators believe the system will be of great bene!t to dam and hydropower plant operations involved in silt extraction projects and the creation, stabilisation and restoration of watercourses.

Sedi-!lters have been designed to dewater large volumes of water-based slurries generated from maintenance operations on lakes and waterways and from industrial processes. They can also be used to create arti!cial weirs, berms and reefs in watercourses, and for ero-sion control in the marine environment.

Mark Clayton, managing director of Aardvark, has been heavily involved in the development of Sedi-!lter. “Sedi-!lter is of great help in terms of extracting silt as well as playing a key role in stabilising watercourses by using !lled dewatering bags in the water to help sta-bilise banks,” he says. “There is really no limit when it comes to the depth of water Sedi-!lter can work in. We are looking at a project in the Thames Estuary, near Canary Wharf, where they would operate at a depth of 8m with no problems.”

Sedi-filters have already provided Midlands-based Blue Boar Contracts – which has a national contract with British Waterways to dredge canals to a navigable depth – with an environmentally-friendly solution to the problem of containing and dewatering sediment in con!ned areas and holding and treating contaminated sediment.

In a pilot project, the company used Sedi-!lter’s bespoke dewater-ing bags to contain and dewater sediment taken from a 3km stretch of the Birmingham and Worcester Canal in the heart of Birmingham city. After successful results during the three-month pilot project, the company is now using Sedi-!lter’s dewatering system to deal with most of its contaminated sediment.

The dewatering system has a strong environmental bene!t and can be effective in a wide variety of dewatering and engineering applica-tions, says the developers. The main gain is the removal of water from

sediment, transforming it into a drier state, which helps handling and enables the sediment to be disposed of to land!ll or used elsewhere.

Blue Boar director Simon Potter is impressed with the way the system has helped his company’s work: “The use of the Sedi-!lter system means that we don’t have to add anything to the contaminated sedi-ment to treat it before it is disposed of. That means we don’t have to have a special licence to deal with the waste and we are not increasing the weight of the sludge. We can dry it out using the Sedi-!lter system, so it can be accepted to land!ll and, because the water is extracted, we are actually reducing the amount we are taking away. This means lower transport costs and less weight at the land!ll weighbridge.”

DEWATERING SOLUTION

Sedi-!lter dewatering systems have been created to tackle the environ-mental problems associated with excavating and storing wet slurry, sludges and sediments. Made from high-quality geotextiles, Sedi-!lter is designed to effectively capture solid materials without the use of excessive or specialist machinery. It removes excess water from wet wastes, such as sludges, dredged silts and washwaters, through a pas-sive !ltration process. Solids are held within the tube, as the water passes through the fabric and "ows back to its original source, sur-rounding ground or another collection point. The result is a signi!-cant reduction in the volume of solid waste that has to be handled and dealt with – as up to 90% of the water is removed.

If the solid waste is contaminated, like the canal sediment, then the wet material can be placed in the Sedi-!lter and the water extracted. The Sedi-!lter can be used to contain contaminated sediment whilst treat-ment is applied, as dewatering itself does not decontaminate sediment.

The bag is made of a close weave textile, which aids the dewater-ing process. The !lters are engineered to withstand pressure at the base, which allows for stacking. They can be made to almost any size depending on application. The standard size is 7m wide x 33m long – with a volume of approximately 250m3.

Filling is via pumping, the dorsal openings at the top centre of the bag combine an entry port and sleeve, this allows a pipe to be inserted and clamped inside the sleeve. Filling is controlled through a mani-fold/valve system, each tube is !lled and allowed to dewater. Once dewatered, the Sedi-!lter is !lled again and the process is repeated, until the dewatered sediment volume is approximately 80%.

A wide variety of treatments can be applied to the slurry during and after pumping. Air lines can be run through and clamped in place and microbes added, as well as mixing and agitation.

www.sedi-!lter.co.uk

IWP& DC

A new dewatering system offers the dams and hydropower industry a solution to sedimentation problems

All systems go for Sedi-filter


COMMENT

OVER the past 58 years, the author has been fortunate to work on both large and small hydro developments, and managed to keep detailed statistics on project engi-neering services. The author found that there was a

vast difference in the project documentation required by a private utility, as compared with that demanded by a public utility. Also, there was a signi!cant difference in how the design and construc-tion work was undertaken for small as compared with large hydro developments. After many years, a distinct pattern in man-hours was discerned, as will be discussed in this paper.

PROJECT ENGINEERING MAN-HOURS

After completion of a feasibility report, one of the !rst questions asked by the hydro project owner; is how much will the detailed engineering work cost? This is very dif!cult for the consultant to estimate with any degree of accuracy. It was found to depend on several factors:

How much documentation will be required by the owner? How will equipment bids be analyzed and what justi!cation will be required on contractor selection? How will orders for the equipment be placed? Will the owner question all invoices for the engineering services?

The answers to these questions will directly affect the man-hours required to undertake the design and project management, resulting in two types of engineering services offered to owners – (1) a docu-mented design service, and (2) a non-documented design service.

A documented design would entail the production of:

A ‘Design Criteria report’: A document showing the criteria to be used in design of each structure, forwarded to the client for perusal by the client’s Review Board, prior to starting detailed designs. A ‘Design Transmittal’: A document showing how each structure was designed, for permanent retention in the client’s project !les, to be used whenever there are repairs or modi!cations to the structure. A ‘Contract Award document’: A report on how the contractor was selected, to include all speci!cations and correspondence with the selected contractor prior to award. A ‘Project Completion Report’: This document would include copies (on CD) of all project drawings and photographs, and copies of all progress reports issued during construction. A ‘Project Operating Manual’.

Such detailed engineering services would normally be required for all major hydro developments, by large utilities and for international bank-!nanced projects.

A non-documented design is one where a client or contractor is willing to entrust the engineering services to a consultant, without requiring any documentation on the design or construction, and the only documentation provided would be: a copy of all project drawings; and an operating manual. This standard of work would be equivalent to the design work undertaken by a consultant for the

general contractor on a design-build project, or that required for a small hydro development of less than about 50MW capacity.

From 1952 until 1990, the author worked for Montreal Engineering (Monenco), a consultant who provided design, construc-tion and operating services to many associated hydro utilities. These utilities did not require any detailed project documentation; hence the author was able to accumulate data for non-documented engineer-ing services, where most of the contracts for construction, turbine and generator were negotiated with reliable known contractors and manufacturers. Bids for other equipment were solicited from, at most, three manufacturers. Speci!cations were concise. For example, all the technical speci!cations for civil works and mechanical equipment at the 356MW Brazeau project were contained in a 2.5cm three-ring binder. About 1960, Monenco began providing services to ‘outside clients’ who required more formalized engineering with full documen-tation of the work, and required all contracts to be open for bidding by pre-quali!ed contractors. As a result, speci!cations became more detailed and contractual conditions more complex. This provided an opportunity to obtain data on documented designs. The results are shown in Table 1, where the data was accumulated over 32 years between 1954 and 1986 for 8 non-documented projects and for nine documented projects.

One of the !rst questions owners ask is ‘what will be the cost of engineering services’. This paper discusses the effect of documented/non-documented designs on project engineering costs, based on detailed man-hour data obtained from 17 hydro projects ranging in size from the 6.4MW Maggoty development in Jamaica, to the 2304MW La Grande 3 development in Quebec. By J L Gordon, P.Eng

Hydro project engineering costs

Project man-hour statisticsProject Head

(m)Capacity (MW)

MW/h0.3 Man-hours

Non-documented projects

1. Maggoty (Jamaica) 88 6.1 1.6 10,850

2. Snare Falls (Canada) 19 6.7 2.8 28,900

3. Umtru (India) 58 11.7 3.5 16,300

4. Rattling Brook (Canada) 94 12.5 3.2 20,220

5. Taltson (Canada) 30 18.3 6.6 22,176

6. Bearspaw (Canada) 15 15.2 6.7 17,460

7. Bighorn (Canada) 75 110 30.1 86,400

8. Brazeau plant (Canada) 118 336 91.2 97,410

Brazeau pump (Canada) 7.6 20

Documented projects

9. Charlot River (Canada) 29 11 4.0 45,100

10. Dadin Kowa (Nigeria) 28 34 12.5 66,000

11. Maskekeya Oya (Sri Lanka) 578 100 14.8 97,674

12. Andekaleka (Madagascar) 214 112 22.4 135,000

13. Cat Arm (Canada) 381 136 22.9 167,00

14. Wreck Cove (Canada) 350 200 34.5 131,200

15. Bayano (Panama) 50 300 92.8 261,000

16. Jebba (Nigeria) 28 560 206.1 352,00

17. La Grande (Canada) 79 2304 621.1 630,000


COMMENT

Analyzing the data, the author found that there is a factor of about 2.5 between a ‘documented’ as compared with a ‘non-documented’ design and managed project, as shown in Figure 1. There are two distinct lines on the !gure. The lower line (B) represents the man-hours for a ‘non-documented’ design, and the upper line (A) represents a documented design. Both lines can be expressed by the following equation

Man-hours = k (MW/h0.3)0.54 (1)

Where: h = rated net turbine head in meters; MW = installed capacity in megawatts; k = a factor with a value = 8,300 for a non-documented design, and = 21,000 for a documented design.

In other words, a documented project requires over 2.5 times the effort expended on a non-documented project. This is very important, and a factor which must be taken into account by any owner contem-plating awarding a contract for engineering services.

There are some projects on the chart which do not !t the data. These can be explained by:

2 – Snare Falls. The dam site on this project was changed at the last minute, when the owner decided that the project capacity should be increased by about 50%. This was accomplished by moving the dam site downstream to the next set of rapids, after all contracts had been issued for tender. This required a complete re-design of the project layout. 4 – Rattling Brook. This project proceeded with only a pre-fea-sibility study, requiring extensive additional studies on dam and spillway locations. 10 – Dadin Kowa. This project was terminated when the client ran out of money, and still requires completion of the powerhouse and installation of spillway gates. 13 – Cat Arm. During the design engineering work, the owner decided to add about six utility engineers to the consultant’s electri-cal design team to learn how to design the automatic controls, with the intent to retro!t the design onto older powerplants. Also, there were signi!cant changes to the project concept when detailed design work commenced, which included use of a U-shaped weir spillway instead of a gated spillway, impulse units instead of Francis units, and elimination of the surge tank. 7 – Bighorn. This project was undertaken after a change in the man-agement at the utility. The new management required all contracts to be tendered instead of being negotiated, adding substantially to the weight of both the technical and contractual conditions in speci-!cations, and requiring more formal documentation of the work.

It is remarkable how consistent the data appears to be. All of the projects were undertaken by Monenco, with the exception of Wreck Cove, engineered by SNC, with Monenco acting as the owner’s consultant, and LG3, engineered by SNC in association with Cartier Engineering, a subsidiary of Monenco. Also, two of the projects, at Maskeliya Oya and Bayano, were designed

from project of!ces in Colombo and Panama, staffed with a few Canadian engineers, with all the other engineers and draftsmen being provided by the utility client.

The chart is based on data from projects undertaken before the intro-duction of computerized drafting, (CAD) which one would expect to reduce drafting time. The author has tried to determine whether CAD has had a signi!cant effect on man-hours, to no avail, since consult-ants are naturally reluctant to divulge such data. However, the author is of the opinion that CAD and other similar programs have instead increased drafting time, since now it is very easy to produce more draw-ings, and to produce three-dimensional images of powerplant interiors and even individual concrete pours, both of the latter requiring signi!-cant additional input data. The added engineering simpli!es construc-tion work, but increases engineering man-hours.

Also, the work was undertaken before personal computers became available. Again, one would expect that computers would reduce the engineering effort. However, based on observing the extent and detail of recent speci!cations for large developments, the author is of the opinion that computers have indeed facilitated, but have also increased engineering man-hours.

HYDRO SPECIFICATIONS FOR DOCUMENTED AND NON-DOCUMENTED PROJECTS

This raises the issue of the effort required to produce speci!cations and contract documents. A perfect illustration of the difference is shown in Figure 2, where the large 3-ring binder contains the technical speci!ca-tions only for the civil works on a medium-sized documented 200MW hydro project, and the small document on the left contains the civil speci!cations, the geological report, contractual conditions and the environmental guidelines for the civil works contract at a small low-head non-documented 600kW hydro development. The right-hand document was produced by a large consultant in Vancouver, and the other document by a small consultant in Halifax.

The author is of the opinion that it is very dif!cult for a large hydro consultant to produce a short speci!cation. Large consultants have the ability to retain specialists in many disciplines, and consequently have few ‘generalists’ able to work on a variety of structures and equipment. For example, the mechanical department in a large con-sultant’s of!ce could have an engineer specializing in powerhouse cranes, another in gantry and gate hoists, another in powerhouse pumps, compressors and piping, and another in turbines. All would be required to contribute towards an equipment speci!cation, and the result would be a document requiring considerable co-ordination between the specialists. On the other hand, a small consultant would have perhaps only one mechanical engineer, and this person would be required to produce the speci!cations for all the mechanical equip-ment. The resulting document would be more concise than that pro-duced by the large consultant.

DOCUMENTED PROJECT DESIGN AND MANAGEMENT

To illustrate the difference in project management between a docu-mented and non-documented work, the data for the large document-ed Jebba hydro project is presented. Jebba is located on the Niger River in Nigeria, and includes a large shiplock. It was commissioned in 1984. It has an installed capacity of 560MW at 27.6m head from 6 vertical axis Kaplan turbines. The completed project can be clearly viewed on Google Earth at 9-08-20N, 4-47-27E.

Major project quantities at Jebba included:

Earth excavation: 1,230,000m3. Rock excavation: 3,270,000m3. Earth !ll: 2,120,000m3. Rock !ll and rip-rap: 2,930,000m3. Spillway, lock, weir concrete: 241,000m3. Powerhouse concrete: 245,000m3.

Total cost of the project was over $1B in 1980 US$. Time spent on engineering and project management was 386,000

1,000.000

100,000

10,000

Man

hour

s

1 10 100 1,000MW/h 0.3>

Non-documented projects

Documented projects

24

107

13

A

B

Figure 1: Design engineering man-hours


COMMENT

man-hours, of which 27% (104,000mh) was on project management and construction supervision. The project was fully documented, which required the production of both “design criteria” documents and “design transmittal reports” for each of the nine major structures. Based on detailed statistics maintained through-out project execution, the project management group supervised the production and distribution of:

23 contract documents, with a total of 2478 pages of technical speci!cations, plus contractual conditions. 364 tender drawings. 1406 construction drawings. 7335 manufacturer’s drawings received for review by the design engineers. 131 construction reports, with a total of 12,569 pages.

The production of drawings had to be kept ahead of the contractors’ requirements, and peaked at 512 approved for construction draw-ings issued in the month of February 1980. Of course, it was not possible to engineer such a large number of drawings in one month; they were produced over the previous year when design staff peaked at 72 individuals. The general civil work contract was signed at the end of January 1978, and in March seven copies of 198 drawings were packed in a large box and sent by air freight to the contrac-tors head of!ce, knowing that it was essential to keep ahead of the contractors requirements for detailed construction drawings.

Cost control was maintained by an accounting team at site, and was complicated by having to use four currencies – US dollars, Italian Lira, Japanese Yen and German Marks. During construction, it was dif!cult to determine the current total cost due to the constant change in the relative value of the currencies. The project was completed in 1984, after six years of construction. Management staff averaged nine persons over this period, and peaked at 13.

NON-DOCUMENTED PROJECT DESIGN AND MANAGEMENT

A non-documented design will not require such a large project man-agement team as at Jebba. Another factor to be taken into account is the recent use of water-to-wire equipment contracts, wherein the contractor undertakes a major proportion of the powerhouse elec-trical and mechanical design work. This means that the consultant can often dispense with the services of electrical and mechanical engineers, further reducing the cost of project execution. Another

factor is the introduction of high speed internet services over the last decade. This has allowed many engineers and technicians to work from home, working within informal groups to provide design serv-ices for small hydro projects. There are several such groups, where a hydrologist, civil engineer, geotechnical engineer and a CAD drafts-man produce all drawings, and all working from home.

An early demonstration of this concept was provided at Ragged Chute, where the addition of a small 6.3MW, 13m head development at an existing dam in Canada was undertaken in 1992. The work was supervised by the owner (a retired contractor) from a rented nearby cottage, a civil engineer and draftsman with no hydro experience were engaged to undertake powerhouse and intake design, another to design the penstock, a senior hydro consultant provided advice, and costs were audited by a hydro engineer appointed by the bank providing the !nancing. A geotechnical engineer was engaged to pro-vide advice on slope stability during excavation work. Ragged Chute is located at 47-16-35N, 79-40-19W, and is clearly visible on Google Earth. Total staff involved were; three engineers (owner + civil + draftsman) for about 18 months, plus another four engineers very much part-time. There was a water-to-wire contract for the equip-ment, and a general contractor undertook the construction and also designed the plant plumbing, heating, lighting and ventilation sys-tems. There was no documentation other than an operating manual provided by the water-to-wire contractor, and a set of drawings.

CONCLUSIONS

The !rst decision facing a hydro owner is how much documentation of the project execution work will be necessary? For large projects, documentation is required. There is a grey zone between about 25MW and 100MW where documentation is optional. However, for small hydro work, of less than about 50MW, documentation should be kept to a bare minimum.

Recently, the author has seen speci!cations issued by hydro utilities for engineering services. They include extensive requirements for very detailed project documentation, even for small hydro projects, and the author is of the opinion that such speci!cations have been issued without understanding the effect on engineering costs. It is hoped that this paper will help to clarify such issues.

Jim Gordon is an independent hydropower consultant, and can be reached at – [email protected]

IWP& DC

Small – large hydro specifications compared

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